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Bikini Incision vs Longitudinal Incision for Anterior Total Hip Arthroplasty: A Systematic Review

Open AccessPublished:July 31, 2022DOI:https://doi.org/10.1016/j.artd.2022.06.010

      Abstract

      Background

      Direct anterior approach total hip arthroplasty (DAA THA) traditionally involves a longitudinal incision, but a bikini incision may improve postoperative scar cosmesis and patient satisfaction while reducing wound complications. This systematic review compares the clinical outcomes and surgical complications in patients undergoing DAA THA via a bikini vs longitudinal incision.

      Methods

      A Preferred Reporting Items for Systematic Review and Meta-Analyses-compliant search of PubMed, Cochrane, and EMBASE was performed to identify original articles comparing patients undergoing DAA THA via a bikini vs longitudinal incision published from 2010 to 2021. Patient demographic data and postoperative outcomes (scar appearance, patient satisfaction, functional hip scores, and complications) were collected and qualitatively evaluated.

      Results

      A total of 8 double-armed studies were included, allowing comparison of clinical outcomes of a bikini incision (n = 952) vs a longitudinal incision (n = 1361). Three out of 4 (75.0%) studies comparing postoperative scar appearance and patient satisfaction reported improvements following bikini incision, while 1 study reported comparable results between incision types. Postoperative hip function was similar between incision types in 3 of 4 (75.0%) studies comparing this outcome. Lateral femoral cutaneous nerve injury was the most frequently reported complication following anterior THA, but rates were low overall, and most injuries resolved.

      Conclusions

      Bikini incision appears to be a safe alternative to the traditional longitudinal incision, with similar functional hip outcomes and potentially improved cosmesis and patient satisfaction while reducing wound complications. Current evidence suggests an elevated risk of lateral femoral cutaneous nerve injury with bikini incision, but this needs to be confirmed in further prospective randomized studies.

      Keywords

      Introduction

      Total hip arthroplasty (THA) is becoming increasingly common in the United States; the rate of THA procedures doubled from 2000 to 2010, with over 310,000 procedures being performed in patients aged 45 years and older [
      • Wolford M.L.P.K.
      • Bercovitz A.
      Hospitalization for total hip replacement among inpatients aged 45 and over: United States, 2000–2010. NCHS data brief, no 186.
      ]. The annual volume of THA procedures is predicted to increase to 850,000 in 2030, with the highest increase in the 45- to 54-year age group [
      • Singh J.A.
      • Yu S.
      • Chen L.
      • Cleveland J.D.
      Rates of total joint replacement in the United States: future projections to 2020-2040 using the national inpatient sample.
      ]. Recent studies have demonstrated that the direct anterior approach (DAA) for THA is associated with faster recovery, reduced muscle damage, reduced hospital length of stay, and improved postoperative pain and hip function [
      • Miller L.E.
      • Gondusky J.S.
      • Bhattacharyya S.
      • Kamath A.F.
      • Boettner F.
      • Wright J.
      Does surgical approach affect outcomes in total hip arthroplasty through 90 days of follow-up? A systematic review with meta-analysis.
      ,
      • Taunton M.J.
      • Mason J.B.
      • Odum S.M.
      • Springer B.D.
      Direct anterior total hip arthroplasty yields more rapid voluntary cessation of all walking aids: a prospective, randomized clinical trial.
      ,
      • Martin C.T.
      • Pugely A.J.
      • Gao Y.
      • Clark C.R.
      A comparison of hospital length of stay and short-term morbidity between the anterior and the posterior approaches to total hip arthroplasty.
      ,
      • Taunton M.J.
      • Trousdale R.T.
      • Sierra R.J.
      • Kaufman K.
      • Pagnano M.W.
      John charnley award: randomized clinical trial of direct anterior and miniposterior approach THA: which provides better functional recovery?.
      ,
      • Zhao H.Y.
      • Kang P.D.
      • Xia Y.Y.
      • Shi X.J.
      • Nie Y.
      • Pei F.X.
      Comparison of early functional recovery after total hip arthroplasty using a direct anterior or posterolateral approach: a randomized controlled trial.
      ]. Compared to traditional surgical approaches, the DAA is also associated with lower rates of complications including reoperation, dislocation, and infection [
      • Miller L.E.
      • Gondusky J.S.
      • Kamath A.F.
      • Boettner F.
      • Wright J.
      • Bhattacharyya S.
      Influence of surgical approach on complication risk in primary total hip arthroplasty.
      ].
      DAA THA traditionally involves a longitudinal incision overlying the tensor fasciae latae, perpendicular to the tension lines of the skin. However, excessive scar formation and poor cosmesis with impaired wound healing can often result [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ,
      • Christensen C.P.
      • Karthikeyan T.
      • Jacobs C.A.
      Greater prevalence of wound complications requiring reoperation with direct anterior approach total hip arthroplasty.
      ,
      • Jahng K.H.
      • Bas M.A.
      • Rodriguez J.A.
      • Cooper H.J.
      Risk factors for wound complications after direct anterior approach hip arthroplasty.
      ]. Alternatively, the bikini incision runs parallel to the anatomic skin tension lines, often resulting in decreased scar formation and improved cosmesis [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ]. The incision is marked in line with the flexion crease approximately 6-8 cm in length, with two-thirds of the incision length being lateral to the anterosuperior iliac spine landmark and one-third medial; the incision and resultant cosmesis has been previously described in detail [
      • Corten K.
      • Holzapfel B.M.
      Direct anterior approach for total hip arthroplasty using the “bikini incision”.
      ,
      • Berry D.J.
      • Lieberman J.
      Surgery of the hip E-book.
      ]. Both incisions are shown in Figure 1.
      Figure thumbnail gr1
      Figure 1Longitudinal (a) and bikini (b) incisions. Intraoperative photo of a right hip with anterosuperior iliac spine landmark on the left side of image with the caudal extent of the patient to the right side of image.
      DAA with a bikini incision has been introduced fairly recently [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ] and is generally utilized by experienced surgeons after achieving proficiency with the traditional anterior approach via a longitudinal incision. Thus, studies reporting the clinical outcomes of a bikini incision THA are limited. This study systematically reviewed the literature comparing clinical outcomes and/or complications of patients who underwent DAA THA via a bikini vs longitudinal incision.

      Material and methods

      Search protocol

      A prospective registered systematic review (PROPSPERO-CRD42021249672) of the literature was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses checklist [
      • Page M.J.
      • Moher D.
      • Bossuyt P.M.
      • Boutron I.
      • Hoffmann T.C.
      • Mulrow C.D.
      • et al.
      PRISMA 2020 explanation and elaboration: updated guidance and exemplars for reporting systematic reviews.
      ]. A comprehensive search was conducted in the PubMed, Cochrane, and EMBASE databases from January 1, 2010, through August 31, 2021, using an automated search tool (AutoLit; Nested Knowledge, Saint Paul, MN). The specific search strings used for the literature search are listed in Supplementary Table 1.

      Study selection

      Original studies comparing relevant clinical outcomes for patients who underwent DAA THA (direct anterior or anterior supine intermuscular approach) using a bikini vs longitudinal incision were included. Exclusion criteria were 1) non-English language studies; 2) studies published before January 1, 2010; 3) systematic/narrative reviews and meta-analyses; 4) opinion pieces, editorials, commentaries, letters, technical notes, and abstracts; 5) single-arm studies, case series, or case reports; 6) preclinical (in vitro, cadaveric, or animal) studies; 7) irrelevance to the study topic; and 8) insufficient surgical details (including any study that did not specify incision type).

      Data extraction

      Baseline data collected included age, sex, and body mass index (BMI, kg/m2). Primary outcomes of interest were scar cosmesis, patient satisfaction, functional hip outcomes, and postoperative complications, including lateral femoral cutaneous nerve (LFCN) injury (inclusive of neuropraxia, dysesthesia, and hypoesthesia), heterotopic ossification (HO), revision, superficial or deep infection, delayed wound healing, fracture, and dislocation. Follow-up period was extracted for each study.

      Statistical analysis

      This review presents a qualitative synthesis of data obtained from the included studies. Continuous variables, when available, are reported as frequency (count), mean, standard deviation, and range (minimum and maximum). Dichotomous/categorical variables are reported as a discrete number and percentage of subjects for each study arm.

      Results

      Search results

      There were 480 unique studies identified in the literature search. One additional study was included via expert review and recommendation [
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ]. After screening based on titles/abstracts, 22 studies were selected for full-text review. Fourteen studies were excluded for a lack of comparison arm, irrelevance, not the bikini incision, or full texts unavailable, leaving 8 comparative studies eligible for final inclusion in this qualitative review (Fig. 2) [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ,
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ,
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ,
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ,
      • Menzies-Wilson R.
      • Marino I.T.
      • Mahalingham K.
      • Field R.
      Functional outcomes of direct anterior approach hip arthroplasty: oblique ‘bikini’ versus longitudinal skin incision.
      ,
      • Rudiger H.A.
      • Dittrich M.
      • Robinson J.
      • Mansour T.
      • Schwab T.
      • Stadelmann V.A.
      • et al.
      The impact of heterotopic ossification on self-reported outcomes after total hip arthroplasty using the direct anterior approach.
      ,
      • Wang Q.
      • Yang Y.
      • Yang Z.
      • Hu Y.
      • Zhao X.
      • Chen C.
      • et al.
      Analgesic effects of ultrasound-guided iliohypogastric/ilioinguinal nerve block combined with lateral femoral cutaneous nerve block in total hip arthroplasty via direct anterior approach: a retrospective cohort study.
      ,
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ].
      Figure thumbnail gr2
      Figure 2Preferred Reporting Items for Systematic Review and Meta-Analyses flow diagram.
      These 8 studies included 2 randomized controlled trials (RCTs) [
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ,
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]. Two studies compared a singular complication between the incision types, 1 being HO and the other being LFCN injury [
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ,
      • Rudiger H.A.
      • Dittrich M.
      • Robinson J.
      • Mansour T.
      • Schwab T.
      • Stadelmann V.A.
      • et al.
      The impact of heterotopic ossification on self-reported outcomes after total hip arthroplasty using the direct anterior approach.
      ].

      Demographic and baseline characteristics

      Table 1 summarizes study characteristics and patient demographics. The included studies reported a total of 2313 patients that underwent DAA THA using a bikini (n = 952) vs longitudinal incision (n = 1361). Seven studies reported mean age and sex proportion; in the bikini incision group, mean patient age ranged from 54.3 [
      • Wang Q.
      • Yang Y.
      • Yang Z.
      • Hu Y.
      • Zhao X.
      • Chen C.
      • et al.
      Analgesic effects of ultrasound-guided iliohypogastric/ilioinguinal nerve block combined with lateral femoral cutaneous nerve block in total hip arthroplasty via direct anterior approach: a retrospective cohort study.
      ] to 70 [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ] years, and the majority of reported patients were female (550/952; 57.8%). In the longitudinal incision group, the mean patient age ranged from 55 [
      • Wang Q.
      • Yang Y.
      • Yang Z.
      • Hu Y.
      • Zhao X.
      • Chen C.
      • et al.
      Analgesic effects of ultrasound-guided iliohypogastric/ilioinguinal nerve block combined with lateral femoral cutaneous nerve block in total hip arthroplasty via direct anterior approach: a retrospective cohort study.
      ] to 67.4 [
      • Menzies-Wilson R.
      • Marino I.T.
      • Mahalingham K.
      • Field R.
      Functional outcomes of direct anterior approach hip arthroplasty: oblique ‘bikini’ versus longitudinal skin incision.
      ] years, and the majority of reported patients were female (620/1132; 54.8%). Mean BMI data were available in 6 studies and ranged from 23.2 [
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ] to 25.6 [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ] in the bikini group and from 23.8 [
      • Wang Q.
      • Yang Y.
      • Yang Z.
      • Hu Y.
      • Zhao X.
      • Chen C.
      • et al.
      Analgesic effects of ultrasound-guided iliohypogastric/ilioinguinal nerve block combined with lateral femoral cutaneous nerve block in total hip arthroplasty via direct anterior approach: a retrospective cohort study.
      ] to 28 [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ] in the longitudinal group.
      Table 1Summary of studies included in the systematic review.
      Author, yearStudy typeIncision typeSample sizeSex (female)Mean age (y)Mean BMI (kg/m2)
      Leunig et al., 2013 [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ]
      Retrospective cohortBikini2620 (76.9)70.025.0
      Longitudinal3310 (30.3)66.028.0
      Leunig et al., 2018 [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ]
      Retrospective cohortBikini398227 (57.0)66.025.6
      Longitudinal556256 (46.0)67.025.8
      Manrique et al., 2019 [
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ]
      Retrospective case-controlBikini8676 (88.4)61.925.3
      Longitudinal230200 (86.9)63.326.1
      Menzies-Wilson et al., 2020 [
      • Menzies-Wilson R.
      • Marino I.T.
      • Mahalingham K.
      • Field R.
      Functional outcomes of direct anterior approach hip arthroplasty: oblique ‘bikini’ versus longitudinal skin incision.
      ]
      Retrospective cohortBikini9033 (36.7)65.5NR
      Longitudinal12454 (43.5)67.4NR
      Rüdiger et al., 2020 [
      • Rudiger H.A.
      • Dittrich M.
      • Robinson J.
      • Mansour T.
      • Schwab T.
      • Stadelmann V.A.
      • et al.
      The impact of heterotopic ossification on self-reported outcomes after total hip arthroplasty using the direct anterior approach.
      ]
      Retrospective cohortBikini17288 (51.2)NRNR
      Longitudinal229NRNRNR
      Sang et al., 2021 [
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ]
      RCTBikini9967 (67.7)60.723.2
      Longitudinal9663 (65.6)61.424.7
      Wang et al., 2021a [
      • Wang Q.
      • Yang Y.
      • Yang Z.
      • Hu Y.
      • Zhao X.
      • Chen C.
      • et al.
      Analgesic effects of ultrasound-guided iliohypogastric/ilioinguinal nerve block combined with lateral femoral cutaneous nerve block in total hip arthroplasty via direct anterior approach: a retrospective cohort study.
      ]
      Retrospective cohortBikini3216 (50.0)54.325.0
      Longitudinal4318 (41.9)55.023.8
      Wang et al., 2021b [
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]
      RCTBikini4923 (46.9)56.824.3
      Longitudinal5019 (38.0)55.924.2
      NR, not reported; RCT, Randomized controlled trial.
      Data presented as frequency (n) or n (%).

      Wound healing

      Two studies compared wound healing between patients with bikini vs longitudinal incision following DAA THA [
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ,
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]. A comparative study by Manrique et al. found that patients with bikini incisions (2.3%, 2/86) had lower rates of delayed wound healing than those with longitudinal incisions (6.1%, 14/230) at 20 days postoperatively although the difference was not found to be significant (P = .09) [
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ]. In patients with BMI >30 kg/m2, the difference in delayed wound healing was significant (bikini 0% [0/16] vs longitudinal 16.6% [8/48]; P < .05) [
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ]. Another recent RCT by Wang et al. found there was an increase in delayed wound healing with a longitudinal incision (12.0% [6/50]; P = .123) vs bikini (2.0% [1/49]) at 2 weeks postoperatively; however, this was not statistically significant [
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]. Additional details are in Table 2.
      Table 2Wound healing, cosmesis, and functional outcomes of included studies.
      Author, yFollow-up (mo)Would healing & scar cosmesisFunctional hip outcome
      Leunig et al., 2013 [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ]
      6NRS: similar between groupsWOMAC: similar scores;
      Objective evaluation: narrower (P = .002) and shorter (P = .009) scars in bikini group.OHS: similar scores (longitudinal 19.4 vs bikini 16.9; P = .240);
      UCLA: similar scores (longitudinal 6.4 vs bikini 6.2; P = .516).
      Leunig et al., 2018 [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ]
      24-48UNC4P: lower mean total score in bikini group (P = .01);OHS: similar between groups (longitudinal 45.3 ± 5.1 vs bikini 46.1 ± 3.9; P = .41).
      Scar cosmesis: higher rate of “very satisfied” patients in the bikini group (P < .001).
      Manrique et al., 2019 [
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ]
      6PSAS or the Vancouver scale: similar between groups.NR
      Menzies-Wilson et al., 2020 [
      • Menzies-Wilson R.
      • Marino I.T.
      • Mahalingham K.
      • Field R.
      Functional outcomes of direct anterior approach hip arthroplasty: oblique ‘bikini’ versus longitudinal skin incision.
      ]
      6-24NROHS: lower in bikini group at 6 mo (longitudinal 36.2 ± 5.66 vs bikini 32.9 ± 4.56; P < .001);
      Overall change in OHS: similar between groups at 6 mo.
      Rüdiger et al., 2020 [
      • Rudiger H.A.
      • Dittrich M.
      • Robinson J.
      • Mansour T.
      • Schwab T.
      • Stadelmann V.A.
      • et al.
      The impact of heterotopic ossification on self-reported outcomes after total hip arthroplasty using the direct anterior approach.
      ]
      3NRNR
      Sang et al., 2021 [
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ]
      6NRNR
      Wang et al., 2021a [
      • Wang Q.
      • Yang Y.
      • Yang Z.
      • Hu Y.
      • Zhao X.
      • Chen C.
      • et al.
      Analgesic effects of ultrasound-guided iliohypogastric/ilioinguinal nerve block combined with lateral femoral cutaneous nerve block in total hip arthroplasty via direct anterior approach: a retrospective cohort study.
      ]
      3NROHS:
      1 mo (longitudinal 32.8 ± 4.1 vs bikini 31.7 ± 4.4),
      3 mo (longitudinal 43.1 ± 3.4 vs bikini 41.3 ± 4.3);
      UCLA:
      1 mo (longitudinal 4.6 ± 0.8 vs bikini 4.8 ± 0.9),
      3 mo (longitudinal 6.2 ± 0.7 vs bikini 6.2 ± 0.5).
      Wang et al., 2021b [
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]
      6SCAR score: lower in bikini group (longitudinal 9.3 ± 2.0 vs bikini incision 7.4 ± 1.8; P < .001)OHS: similar between groups (longitudinal vs bikini)
      Satisfaction: higher in bikini group (longitudinal 38%, 19/50 vs bikini 63.3%, 31/40; P = .013).1 mo (32.3 ± 4.2 vs 32.1 ± 4.7; P = .880),

      3 mo (42.2 ± 4.1 vs 42.0 ± 4.4; P = .854)
      6 mo (45.8 ± 1.6 vs 46.2 ± 1.1; P = .222)
      UCLA: similar between groups (longitudinal vs bikini)
      1 mo (4.6 ± 0.8 vs 4.6 ± 0.6; P = .991)
      3 mo (6.2 ± 0.6 vs 6.1 ± 0.5; P = .836)
      6 mo (6.8 ± 0.7 vs 7.0 ± 0.5; P = .283)
      HHS, Harris Hip score; NR, not reported; NRS, Numeric Rating Scale; PSAS, Patient and Observer Scar Assessment Scale; SCAR, Scar cosmesis assessment & rating scale; UNC4P, The University of North Carolina “4P” scar scale.

      Scar cosmesis

      A total of 4 studies compared postoperative scar cosmesis and patient satisfaction among patients with bikini or longitudinal incision, 3 of which reported significant improvements in the bikini incision group and 1 reported high levels of satisfaction in both groups. An RCT by Wang et al. involving 100 patients (49 bikini; 50 longitudinal; 1 patient lost to follow-up) demonstrated that those with a bikini incision had significantly reduced Scar Cosmesis Assessment & Rating scale scores (bikini 7.4 ± 1.8 vs longitudinal 9.3 ± 2.0; P < .001) with more patients reporting moderate to high levels of satisfaction with the scar appearance (bikini 16.3% [8/49] vs longitudinal 10.0% [5/50]; P = .013) at 6-month follow-up [
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]. Leunig et al. conducted a retrospective study of patients who underwent DAA THA (26 bikini; 33 longitudinal) and found that patients with bikini incision demonstrated improved subjective ratings related to scar cosmesis at 6 months compared to those with a longitudinal incision [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ]. Moreover, the bikini incision group had shorter and narrower scars [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ]. In a long-term study, Leunig et al. followed up 964 patients (398 bikini; 556 longitudinal) after DAA THA with up to 4-year follow-up, finding that patients in the bikini incision group had a lower mean University of North Carolina “4P” scar scale total score (bikini 0.2 vs longitudinal 0.4; P = .01), a lower incidence of peri-incisional numbness (7.5% vs 14.5%; P < .001), and more patients categorized as “very satisfied” with the scar (P < .001) than the longitudinal incision group [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ].
      In contrast, a case-control study of DAA THA (86 bikini; 230 longitudinal) investigated patient-reported scar cosmesis using either the Patient Scar Assessment Scale (bikini mean = 10, range 6-32 vs longitudinal mean = 11, range 6-32; P = .44) or the Vancouver Scale (bikini mean = 6, range 0-12 vs longitudinal mean = 7, range 0-13; P = .26) and found no significant difference in patient satisfaction between the 2 incision groups [
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ]. There were high levels of satisfaction in both groups with over 90% of patients reporting satisfactory appearance of the scar at 6 months [
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ]. Additional details are in Table 2.

      Functional outcomes

      Four studies directly compared postoperative functional hip outcomes between the bikini and longitudinal incisions [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ,
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ,
      • Menzies-Wilson R.
      • Marino I.T.
      • Mahalingham K.
      • Field R.
      Functional outcomes of direct anterior approach hip arthroplasty: oblique ‘bikini’ versus longitudinal skin incision.
      ,
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ], all of which reported no statistical functional difference. Wang et al. conducted an RCT involving 100 patients (49 bikini; 50 longitudinal; 1 patient lost to follow-up) and reported no significant difference in postoperative Oxford Hip Scores (OHS) or University of California Los Angeles (UCLA) activity-level rating scores when comparing bikini (OHS: 46.2 ± 1.1; UCLA: 7.0 ± 0.5) and longitudinal (OHS: 45.8 ± 1.6; UCLA: 6.8 ± 0.7) groups at 6 months (P = .222 and P = .283, respectively) [
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]. Similarly, Leunig et al. reported no significant difference in either OHS, UCLA, or the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score between bikini (OHS: 16.9; UCLA: 6.2; WOMAC function: 11.0) and longitudinal (OHS: 19.4; UCLA: 6.5; WOMAC function: 9.1) incision groups at 6 months (P = .240) [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ]. A similar finding was reported in a long-term follow-up study by Leunig et al. reporting no significant difference in 2- to 4-year postoperative OHS between bikini (46.1 ± 3.9) and longitudinal (45.3 ± 5.1; range 0-48) incision groups (P = .41) [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ]. In contrast, a retrospective analysis by Menzies-Wilson et al. reported a statistically significant difference in 6-month OHS between bikini (n = 90) and longitudinal (n = 124) incision groups (32.89 ± 4.56 vs 36.2 ± 5.66, P = .000) [
      • Menzies-Wilson R.
      • Marino I.T.
      • Mahalingham K.
      • Field R.
      Functional outcomes of direct anterior approach hip arthroplasty: oblique ‘bikini’ versus longitudinal skin incision.
      ]. However, overall change in the OHS was not statistically significant (bikini incision: 10.9 ± 6.4 vs longitudinal: 12.8 ± 6.6; P = .068) and was not considered clinically significant [
      • Menzies-Wilson R.
      • Marino I.T.
      • Mahalingham K.
      • Field R.
      Functional outcomes of direct anterior approach hip arthroplasty: oblique ‘bikini’ versus longitudinal skin incision.
      ]. A retrospective study by Wang et al. reported improvement in functional hip outcomes over time in both incision types but made no conclusion as to the superiority of one over the other [
      • Wang Q.
      • Yang Y.
      • Yang Z.
      • Hu Y.
      • Zhao X.
      • Chen C.
      • et al.
      Analgesic effects of ultrasound-guided iliohypogastric/ilioinguinal nerve block combined with lateral femoral cutaneous nerve block in total hip arthroplasty via direct anterior approach: a retrospective cohort study.
      ]. Additional details are in Table 2.

      LFCN injury

      LFCN injury was assessed in 6 studies [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ,
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ,
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ,
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ,
      • Wang Q.
      • Yang Y.
      • Yang Z.
      • Hu Y.
      • Zhao X.
      • Chen C.
      • et al.
      Analgesic effects of ultrasound-guided iliohypogastric/ilioinguinal nerve block combined with lateral femoral cutaneous nerve block in total hip arthroplasty via direct anterior approach: a retrospective cohort study.
      ,
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ], of which 5 studies compared LFCN injury among patients with bikini and longitudinal incisions [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ,
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ,
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ,
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ,
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]. A recent prospective randomized study of 99 bikini and 96 longitudinal incision DAA THA patients reported a significantly higher incidence of LFCN injury in the bikini group compared to the longitudinal group at 1.5 months postoperatively (36.4% [36/99] vs 21.9% [21/96], P < .05) [
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ]. However, the symptoms resolved over time, and at 6 months, there was no significant difference in the proportion of patients with LFCN symptoms between the incision types (bikini 7.1% [7/99] vs longitudinal 4.2% [4/96]; P = .380) [
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ]. Similarly, another RCT that compared outcomes between the bikini and longitudinal incision groups following DAA THA reported a higher incidence of LFCN dysesthesia in the bikini incision group (28.6%, 14/49) vs the longitudinal incision group (14.0%, 7/50) although this difference was not statistically significant (P = .076) [
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]. Conversely, 2 retrospective studies reported no significant difference in the rates of postoperative LFCN injury between the 2 incision types [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ,
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ]. Interestingly, a retrospective study by Leunig et al. (2018) found that patients with bikini incision had lower rates of LFCN hypoesthesia (P < .001) than those with longitudinal incision [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ]. Additional details are in Table 3.
      Table 3Complications reported in included studies.
      Author, yFollow-up (mo)Complications
      Leunig et al., 2013 [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ]
      6LFCN dysesthesia: similar rates (longitudinal 23% vs bikini 16%; P = .25)
      LFCN hypesthesia: similar rates (longitudinal 60.6% vs bikini 61.5%; P = .942)
      Leunig et al., 2018 [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ]
      24-48LFCN hypoesthesia: lower rate in the bikini group (longitudinal 14.5% vs bikini 7.5%; P < .001)
      HO: similar rates (P = .311)
      Revision: similar rates (longitudinal 2.3%, 13/556 vs bikini 1.5%, 6/398).
      Manrique et al., 2019 [
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ]
      6LFCN dysesthesia: similar rates (longitudinal 3.0%, 7/23 vs bikini 2.3%, 2/86; P = .37);
      Delayed wound healing: similar rates at 20 d (longitudinal 6.1% vs bikini 2.3%; P = .37).
      Menzies-Wilson et al., 2020 [
      • Menzies-Wilson R.
      • Marino I.T.
      • Mahalingham K.
      • Field R.
      Functional outcomes of direct anterior approach hip arthroplasty: oblique ‘bikini’ versus longitudinal skin incision.
      ]
      6-24Superficial wound infection: “clinically irrelevant differences” between groups at 24 mo (longitudinal 0.8% vs bikini 1.1%).
      Rüdiger et al., 2020 [
      • Rudiger H.A.
      • Dittrich M.
      • Robinson J.
      • Mansour T.
      • Schwab T.
      • Stadelmann V.A.
      • et al.
      The impact of heterotopic ossification on self-reported outcomes after total hip arthroplasty using the direct anterior approach.
      ]
      3HO: lower incidence of Brooker grade 3-4 HO in bikini group (longitudinal 11.8%, 27/229 vs bikini 4.0%, 7/172; P = .00011); no Brooker grade 4 HO in bikini group.
      Sang et al., 2021 [
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ]
      6LFCN injury:
      1.5 mo Higher rates in bikini group (longitudinal 21.9%, 23/96 vs bikini 36.4%, 36/99; P = .026)
      6 mo Similar rates (longitudinal 4.2%, 4/96 vs bikini 7.1%, 7/99; P = .380)
      Wang et al., 2021a [
      • Wang Q.
      • Yang Y.
      • Yang Z.
      • Hu Y.
      • Zhao X.
      • Chen C.
      • et al.
      Analgesic effects of ultrasound-guided iliohypogastric/ilioinguinal nerve block combined with lateral femoral cutaneous nerve block in total hip arthroplasty via direct anterior approach: a retrospective cohort study.
      ]
      3LFCN dysesthesia: longitudinal 14.0%, 6/43 vs bikini 15.6%, 5/32
      Venous thromboembolism: longitudinal 2.3%, 1/43 vs bikini 3.1%, 1/32
      Wang et al., 2021b [
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]
      6LFCN injury: similar rates between groups;
      Delayed wound healing: similar rates;
      Infection: similar rates;
      Venous thromboembolism: similar rates.
      NR, not reported.

      Heterotopic ossification

      Two studies directly compared the rate of severe HO (grade 3-4) between incision types [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ,
      • Rudiger H.A.
      • Dittrich M.
      • Robinson J.
      • Mansour T.
      • Schwab T.
      • Stadelmann V.A.
      • et al.
      The impact of heterotopic ossification on self-reported outcomes after total hip arthroplasty using the direct anterior approach.
      ]. Rudiger et al. retrospectively reviewed 401 THA patients (172 bikini; 229 longitudinal) to compare the incidence and severity of HO using the Brooker grade to evaluate anteroposterior and lateral radiographs at 3 months postoperatively [
      • Rudiger H.A.
      • Dittrich M.
      • Robinson J.
      • Mansour T.
      • Schwab T.
      • Stadelmann V.A.
      • et al.
      The impact of heterotopic ossification on self-reported outcomes after total hip arthroplasty using the direct anterior approach.
      ]. Patients with a bikini incision demonstrated a significantly less Brooker grade 3/4 HO (4.0%, 7/172) than those with the longitudinal incision (11.8%, 27/229). Incision type did not affect functional outcomes in this study but significantly influenced the incidence of HO (P = .00013), which was independent of the surgeon’s experience [
      • Rudiger H.A.
      • Dittrich M.
      • Robinson J.
      • Mansour T.
      • Schwab T.
      • Stadelmann V.A.
      • et al.
      The impact of heterotopic ossification on self-reported outcomes after total hip arthroplasty using the direct anterior approach.
      ]. Leunig et al. reported similar rates of HO between the incision types (P = .311); the rates of HO with Brooker ≥2 were 2.5% in the bikini and 6.7% in the longitudinal incision groups, which did not impact the OHS (P = .450) or result in additional surgery [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ]. Additional details are in Table 3.

      Reoperation and implant survival

      Two studies compared revision rates between incision groups [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ,
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ]. Leunig et al. reported no significant difference between bikini incision (1.5%, 6/398) and longitudinal incision (2.3%, 13/556) (P = .911) [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ]; the reasons cited for revisions included dislocation, leg length discrepancy, and periprosthetic fracture. Manrique et al. reported 1 incidence of reoperation (0.4%, 1/230) in patients with bikini incision THA attributed to an acute periprosthetic joint infection [
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ]. Additional details are in Table 3.

      Discussion

      This study systematically reviewed clinical evidence reporting postoperative outcomes and complications following DAA THA using a bikini incision, finding that bikini incisions may result in improved scar cosmesis and decreased wound healing complications, without compromised hip functionality or reoperation rates. However, data reporting surgical complications of the bikini incision THA were heterogeneous and limited the ability to draw conclusions. These results indicate that bikini incision for THA should be further explored as an alternative to the traditional longitudinal incision.
      A traditional longitudinal skin incision is performed perpendicular to the anatomic skin creases, resulting in increased skin edge tension and scar widening; however, an oblique bikini incision follows Langer’s lines and may lead to a narrower scar and improved appearance [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ]. The improved wound healing observed among patients with bikini incisions is thought to be related to reduced tension around the skin edges of the incision compared to the traditional longitudinal incision, which causes constant tension around the skin edges [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ,
      • Lee G.C.
      • Marconi D.
      Complications following direct anterior hip procedures: costs to both patients and surgeons.
      ]. In the 4 studies that compared postoperative scar appearance and patient satisfaction in this review, each used a different assessment method to evaluate scar appearance [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ,
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ,
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ,
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]. Additionally, these studies reported follow-up times ranging from 6 months [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ,
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ] to 2-4 years [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ], so it is difficult to draw strong conclusions about the potential benefits of the bikini incision for scar cosmesis. Taken together, however, the results of this review suggest benefits with the bikini incision in improving the postoperative appearance of the scar and improved scar-related satisfaction in patients following DAA THA. For reference, Figure 3 demonstrates 3-month scar appearances performed by the same author (B.N.).
      Figure thumbnail gr3
      Figure 3Longitudinal and bikini scars at 3 months performed by the same surgeon.
      The relationship between bikini incision and risk of LFCN injury remains somewhat contested. Most of the retrospective studies included in this review demonstrated that the rate of LFCN injury following DAA THA did not vary significantly between patients with longitudinal and bikini incisions [
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ,
      • Manrique J.
      • Paskey T.
      • Tarabichi M.
      • Restrepo C.
      • Foltz C.
      • Hozack W.J.
      Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
      ] although 2 included RCTs indicated that early LFCN outcomes were worse for bikini incision patients [
      • Sang W.
      • Xue S.
      • Xu Y.
      • Liu Y.
      • Zhu L.
      • Ma J.
      Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
      ,
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ]. While the exact mechanism is unclear, bikini incision may raise the risk of injury to the LFCN branches due to greater medial extension over the tensor fasciae latae and reduced intraoperative field, sometimes requiring more forceful retraction [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ,
      • Wang Q.
      • Yue Y.
      • Yang Z.
      • Chen L.
      • Li Q.
      • Kang P.
      Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
      ,
      • Rudin D.
      • Manestar M.
      • Ullrich O.
      • Erhardt J.
      • Grob K.
      The anatomical course of the lateral femoral cutaneous nerve with special attention to the anterior approach to the hip joint.
      ]. Interestingly, evidence shows that LFCN symptoms improve significantly and spontaneously with time [
      • Ozaki Y.
      • Homma Y.
      • Baba T.
      • Sano K.
      • Desroches A.
      • Kaneko K.
      Spontaneous healing of lateral femoral cutaneous nerve injury and improved quality of life after total hip arthroplasty via a direct anterior approach.
      ,
      • Patton R.S.
      • Runner R.P.
      • Lyons R.J.
      • Bradbury T.L.
      Clinical outcomes of patients with lateral femoral cutaneous nerve injury after direct anterior total hip arthroplasty.
      ,
      • Nizam I.
      • Alva A.
      • Gogos S.
      The bikini incision anterior cemented total hip arthroplasty: assessment of radiological and clinical outcomes - a mid-term review.
      ,
      • Alva A.
      • Nizam I.
      • Gogos S.
      Minimizing complications in bikini incision direct anterior approach total hip arthroplasty: a single surgeon series of 865 cases.
      ], so early LFCN injury may not ultimately be an important indicator of surgical success. Further study of these outcomes in larger prospective trials is warranted.
      THA is considered a reliable and valuable treatment. However, complications such as component loosening, instability, fracture, and leg length discrepancy may lead to revision surgery [
      • Lee G.C.
      • Marconi D.
      Complications following direct anterior hip procedures: costs to both patients and surgeons.
      ,
      • Eto S.
      • Hwang K.
      • Huddleston J.I.
      • Amanatullah D.F.
      • Maloney W.J.
      • Goodman S.B.
      The direct anterior approach is associated with early revision total hip arthroplasty.
      ]. Unfortunately, few studies included in this review reported the specific complications leading to revision, making meaningful reoperation comparisons difficult. The only included study that directly compared revision rates between the 2 incision types reported minimal rates of leg length discrepancy, periprosthetic fracture, and dislocation [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ]. The data remain unclear whether there is a difference in revision rates between the 2 incisions.
      It is important to note that the clinical outcomes as well as the rate of postoperative complications of DAA THA, including revisions, are typically higher with surgeons in the initial stages of experience with a given technique. There is a steep learning curve for DAA THA, with 1 study noting that at least 50 procedures are required to obtain revision rates similar to those achieved by experienced surgeons [
      • de Steiger R.N.
      • Lorimer M.
      • Solomon M.
      What is the learning curve for the anterior approach for total hip arthroplasty?.
      ,
      • Meermans G.
      • Konan S.
      • Das R.
      • Volpin A.
      • Haddad F.S.
      The direct anterior approach in total hip arthroplasty: a systematic review of the literature.
      ]. Thus, outcome and complication data should be interpreted considering the experience of the surgeon performing the THA procedure. Additionally, Leunig et al. recommend that the oblique bikini incisions should be utilized only after mastering the DAA approach using the traditional longitudinal incision and in appropriately selected patients [
      • Leunig M.
      • Hutmacher J.E.
      • Ricciardi B.F.
      • Impellizzeri F.M.
      • Rudiger H.A.
      • Naal F.D.
      Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
      ,
      • Leunig M.
      • Faas M.
      • von Knoch F.
      • Naal F.D.
      Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
      ]. This strategy likely ensures that patients receive the most appropriate treatment while minimizing complications. The anterior approach of obtaining femoral exposure traditionally can be more difficult without the proper releases and appropriate incision placement. Figure 4 demonstrates adequate exposure during femoral preparation performed by the same author (C.D.) utilizing the bikini and longitudinal incisions. Another consideration with the bikini incision is distal and proximal extensibility; particularly, how to address intraoperative complications or when needed in complex primary or revision scenarios. Unfortunately, the limited data addressing this issue are purely anecdotal.
      Figure thumbnail gr4
      Figure 4Longitudinal and bikini femoral preparation performed by same surgeon demonstrating adequate exposure for femoral instrumentation.

      Limitations

      The primary limitation of this review was the small number of relevant studies identified for evaluation. There are few articles that discuss bikini incision with THA, so further study is needed to validate the results of this review and draw comparisons between bikini and longitudinal incisions. All the included studies were single-center studies, and the majority were also single-surgeon studies, which inherently limits the generalizability of the results. The rate of complications and outcomes is dependent on the experience of each surgeon with DAA THA and their preferences for a particular incision, but these factors could not be accounted for in this review. Additionally, many of the studies were retrospective in nature. Various assessments utilized patient-reported outcomes, which are subject to response style bias. Considerable heterogeneity existed among the studies regarding patient follow-up and data collection tools, preventing an appropriate meta-analysis assessment with inferential statistics.

      Conclusions

      Evidence suggests that the bikini incision utilized during the DAA THA may be associated with considerable improvement in scar cosmesis with increased patient satisfaction compared to the traditional longitudinal incision, with little to no observed differences in postoperative functional hip outcomes. A greater incidence of LFCN injury may be associated with bikini incision although symptoms can improve over time. Overall, limited and highly heterogeneous studies make it difficult to thoroughly compare bikini and longitudinal incisions; therefore, further prospective randomized studies are warranted.

      Conflicts of interest

      Dr. Charles DeCook receives royalties from DePuy Synthes and is in the speakers’ bureau of or gave paid presentations for DePuy Synthes, Medtronic, and Mizuho.
      For full disclosure statements refer to https://doi.org/10.1016/j.artd.2022.06.010.

      Acknowledgments

      The authors acknowledge Superior Medical Experts and Geeta Paranjape, PhD, for their assistance with literature research and manuscript drafting.

      Appendix A. Supplementary Data

      References

        • Wolford M.L.P.K.
        • Bercovitz A.
        Hospitalization for total hip replacement among inpatients aged 45 and over: United States, 2000–2010. NCHS data brief, no 186.
        National Center for Health Statistics, Hyattsville, MD2015
        • Singh J.A.
        • Yu S.
        • Chen L.
        • Cleveland J.D.
        Rates of total joint replacement in the United States: future projections to 2020-2040 using the national inpatient sample.
        J Rheumatol. 2019; 46: 1134-1140
        • Miller L.E.
        • Gondusky J.S.
        • Bhattacharyya S.
        • Kamath A.F.
        • Boettner F.
        • Wright J.
        Does surgical approach affect outcomes in total hip arthroplasty through 90 days of follow-up? A systematic review with meta-analysis.
        J Arthroplasty. 2018; 33: 1296-1302
        • Taunton M.J.
        • Mason J.B.
        • Odum S.M.
        • Springer B.D.
        Direct anterior total hip arthroplasty yields more rapid voluntary cessation of all walking aids: a prospective, randomized clinical trial.
        J Arthroplasty. 2014; 29: 169-172
        • Martin C.T.
        • Pugely A.J.
        • Gao Y.
        • Clark C.R.
        A comparison of hospital length of stay and short-term morbidity between the anterior and the posterior approaches to total hip arthroplasty.
        J Arthroplasty. 2013; 28: 849-854
        • Taunton M.J.
        • Trousdale R.T.
        • Sierra R.J.
        • Kaufman K.
        • Pagnano M.W.
        John charnley award: randomized clinical trial of direct anterior and miniposterior approach THA: which provides better functional recovery?.
        Clin Orthop Relat Res. 2018; 476: 216-229
        • Zhao H.Y.
        • Kang P.D.
        • Xia Y.Y.
        • Shi X.J.
        • Nie Y.
        • Pei F.X.
        Comparison of early functional recovery after total hip arthroplasty using a direct anterior or posterolateral approach: a randomized controlled trial.
        J Arthroplasty. 2017; 32: 3421-3428
        • Miller L.E.
        • Gondusky J.S.
        • Kamath A.F.
        • Boettner F.
        • Wright J.
        • Bhattacharyya S.
        Influence of surgical approach on complication risk in primary total hip arthroplasty.
        Acta Orthop. 2018; 89: 289-294
        • Leunig M.
        • Hutmacher J.E.
        • Ricciardi B.F.
        • Impellizzeri F.M.
        • Rudiger H.A.
        • Naal F.D.
        Skin crease ‘bikini’ incision for the direct anterior approach in total hip arthroplasty: a two- to four-year comparative study in 964 patients.
        Bone Joint J. 2018; 100-B: 853-861
        • Christensen C.P.
        • Karthikeyan T.
        • Jacobs C.A.
        Greater prevalence of wound complications requiring reoperation with direct anterior approach total hip arthroplasty.
        J Arthroplasty. 2014; 29: 1839-1841
        • Jahng K.H.
        • Bas M.A.
        • Rodriguez J.A.
        • Cooper H.J.
        Risk factors for wound complications after direct anterior approach hip arthroplasty.
        J Arthroplasty. 2016; 31: 2583-2587
        • Leunig M.
        • Faas M.
        • von Knoch F.
        • Naal F.D.
        Skin crease 'bikini' incision for anterior approach total hip arthroplasty: surgical technique and preliminary results.
        Clin Orthop Relat Res. 2013; 471: 2245-2252
        • Corten K.
        • Holzapfel B.M.
        Direct anterior approach for total hip arthroplasty using the “bikini incision”.
        Oper Orthop Traumatol. 2021; 33: 318-330
        • Berry D.J.
        • Lieberman J.
        Surgery of the hip E-book.
        Elsevier Health Sciences, Philadelphia, PA2019
        • Page M.J.
        • Moher D.
        • Bossuyt P.M.
        • Boutron I.
        • Hoffmann T.C.
        • Mulrow C.D.
        • et al.
        PRISMA 2020 explanation and elaboration: updated guidance and exemplars for reporting systematic reviews.
        BMJ. 2021; 372: n160
        • Sang W.
        • Xue S.
        • Xu Y.
        • Liu Y.
        • Zhu L.
        • Ma J.
        Bikini incision increases the incidence of lateral femoral cutaneous nerve injury in direct anterior approach hip arthroplasty: a prospective ultrasonic, electrophysiological, and clinical study.
        J Arthroplasty. 2021; 36: 3463-3470
        • Manrique J.
        • Paskey T.
        • Tarabichi M.
        • Restrepo C.
        • Foltz C.
        • Hozack W.J.
        Total hip arthroplasty through the direct anterior approach using a bikini incision can be safely performed in obese patients.
        J Arthroplasty. 2019; 34: 1723-1730
        • Menzies-Wilson R.
        • Marino I.T.
        • Mahalingham K.
        • Field R.
        Functional outcomes of direct anterior approach hip arthroplasty: oblique ‘bikini’ versus longitudinal skin incision.
        J Orthop Trauma Rehabilitation. 2020; 27: 52
        • Rudiger H.A.
        • Dittrich M.
        • Robinson J.
        • Mansour T.
        • Schwab T.
        • Stadelmann V.A.
        • et al.
        The impact of heterotopic ossification on self-reported outcomes after total hip arthroplasty using the direct anterior approach.
        J Bone Joint Surg Am. 2020; 102: 91-98
        • Wang Q.
        • Yang Y.
        • Yang Z.
        • Hu Y.
        • Zhao X.
        • Chen C.
        • et al.
        Analgesic effects of ultrasound-guided iliohypogastric/ilioinguinal nerve block combined with lateral femoral cutaneous nerve block in total hip arthroplasty via direct anterior approach: a retrospective cohort study.
        Orthop Surg. 2021; 13: 920-931
        • Wang Q.
        • Yue Y.
        • Yang Z.
        • Chen L.
        • Li Q.
        • Kang P.
        Comparison of postoperative outcomes between traditional longitudinal incision and bikini incision in total hip arthroplasty via direct anterior approach: a randomized controlled trial.
        J Arthroplasty. 2021; 36: 222-230
        • Lee G.C.
        • Marconi D.
        Complications following direct anterior hip procedures: costs to both patients and surgeons.
        J Arthroplasty. 2015; 30: 98-101
        • Rudin D.
        • Manestar M.
        • Ullrich O.
        • Erhardt J.
        • Grob K.
        The anatomical course of the lateral femoral cutaneous nerve with special attention to the anterior approach to the hip joint.
        J Bone Joint Surg Am. 2016; 98: 561-567
        • Ozaki Y.
        • Homma Y.
        • Baba T.
        • Sano K.
        • Desroches A.
        • Kaneko K.
        Spontaneous healing of lateral femoral cutaneous nerve injury and improved quality of life after total hip arthroplasty via a direct anterior approach.
        J Orthop Surg (Hong Kong). 2017; 25 (2309499016684750)
        • Patton R.S.
        • Runner R.P.
        • Lyons R.J.
        • Bradbury T.L.
        Clinical outcomes of patients with lateral femoral cutaneous nerve injury after direct anterior total hip arthroplasty.
        J Arthroplasty. 2018; 33: 2919-2919.e1
        • Nizam I.
        • Alva A.
        • Gogos S.
        The bikini incision anterior cemented total hip arthroplasty: assessment of radiological and clinical outcomes - a mid-term review.
        SICOT-J. 2021; 7: 3
        • Alva A.
        • Nizam I.
        • Gogos S.
        Minimizing complications in bikini incision direct anterior approach total hip arthroplasty: a single surgeon series of 865 cases.
        J Exp Orthop. 2021; 8: 1
        • Eto S.
        • Hwang K.
        • Huddleston J.I.
        • Amanatullah D.F.
        • Maloney W.J.
        • Goodman S.B.
        The direct anterior approach is associated with early revision total hip arthroplasty.
        J Arthroplasty. 2017; 32: 1001-1005
        • de Steiger R.N.
        • Lorimer M.
        • Solomon M.
        What is the learning curve for the anterior approach for total hip arthroplasty?.
        Clin Orthop Relat Res. 2015; 473: 3860-3866
        • Meermans G.
        • Konan S.
        • Das R.
        • Volpin A.
        • Haddad F.S.
        The direct anterior approach in total hip arthroplasty: a systematic review of the literature.
        Bone Joint J. 2017; 99-B: 732-740