Articulating vs Static Spacers for Native Knee Infection in the Setting of Degenerative Joint Disease

Open AccessPublished:March 11, 2021DOI:https://doi.org/10.1016/j.artd.2021.01.009

      Abstract

      Background

      Patients with advanced knee arthritis who develop a septic joint are not adequately treated with irrigation and debridement and intravenous antibiotics because of antecedent cartilage damage. The gold standard treatment has been a 2-stage approach. The periprosthetic joint infection literature has demonstrated the superiority of articulating spacers, and metal-on-poly (MOP) spacers are being used with increasing frequency. The purpose of this study was to compare the postoperative outcomes of patients with infected, arthritic knees treated by a 2-stage approach to those of patients who received single-stage treatment with a MOP spacer.

      Methods

      Sixteen patients with native knee septic arthritis treated with an antibiotic spacer between 1998 and 2019 were reviewed. Demographic data, clinical data, knee motion, Knee Society score, Timed-Up-and-Go, and pain scores were collected. Survivorship of final implants was compared.

      Results

      Six of 16 knees (38%) received single-stage treatment, and 10 received 2-stage treatment (62%). Five of 6 MOP spacers (83%) were retained at a mean follow-up of 3 ± 1.2 years. Nine of 10 (90%) receiving static spacers had subsequent reconstruction, with 9 (100%) surviving at mean follow-up of 7 ± 3.2 years. The patients who received MOP spacers trended toward greater terminal flexion, higher Knee Society score, and faster Timed-Up-and-Go at final follow-up.

      Conclusion

      Infection in a native, arthritic knee may be effectively treated using single-stage MOP spacer. Postoperative outcomes of single-stage MOP spacers compare favorably to staged static spacers and with those undergoing revision surgery for other indications. Longer follow-up is needed to evaluate durability of MOP spacers.

      Keywords

      Introduction

      Septic arthritis is an orthopedic emergency requiring prompt treatment because of the potential for serious morbidity and mortality [
      • Matthews C.J.
      • Weston V.C.
      • Jones A.
      • et al.
      Bacterial septic arthritis in adults.
      ,
      • Margaretten M.E.
      • Kohlwes J.
      • Moore D.
      • Bent S.
      Does this adult patient have septic arthritis?.
      ,
      • Nade S.
      Septic arthritis.
      ,
      • Shirtliff M.E.
      • Mader J.T.
      Acute septic arthritis.
      ]. The mainstay of treatment for patients with healthy joints before infection is timely irrigation and debridement of the joint followed by targeted intravenous antibiotics with the goals of infection eradication and cartilage preservation.
      For patients with advanced knee arthritis who develop a septic joint, however, a surgical irrigation and debridement and intravenous antibiotics may adequately address the infection, but not their antecedent pain and deformity. This patient group often has a difficult course because of pre-existing medical comorbidities and the substantial pain and disability associated with accelerated joint degeneration [
      • Vincent G.
      • Amirault J.
      Septic arthritis in the elderly.
      ,
      • Cooper C.
      • Cawley M.
      Bacterial arthritis in the elderly.
      ].
      Once the infection is adequately treated, these patients continue to be a clinical conundrum. Postinfectious joint degeneration may be associated with severe deformity, increasing the complexity of a future arthroplasty. These patients are also at an increased risk for periprosthetic joint infection (PJI) after primary arthroplasty with studies demonstrating an 8%-10% infection rate in this patient population [
      • Seo J.G.
      • Moon Y.W.
      • Park S.H.
      • et al.
      Primary total knee arthroplasty in infection sequelae about the native knee.
      ,
      • Jerry G.J.
      • Rand J.A.
      • Ilstrup D.
      Old sepsis prior to total knee arthroplasty.
      ,
      • Sultan A.A.
      • Mahmood B.
      • Samuel L.T.
      • et al.
      Patients with a history of treated septic arthritis are at high risk of periprosthetic joint infection after total joint arthroplasty.
      ].
      Treatment with a static antibiotic spacer and staged knee arthroplasty is effective [
      • Shaikh A.A.
      • Ha C.-W.
      • Park Y.-G.
      • Park Y.-B.
      Two-stage approach to primary TKA in infected arthritic knees using intraoperatively molded articulating cement spacers.
      ,
      • Chang M.J.
      • Song M.K.
      • Shin J.H.
      • et al.
      Two-stage approach to total knee arthroplasty using colistin-loaded articulating cement spacer for vancomycin-resistant Pseudomonas aeruginosa infection in an arthritic knee.
      ,
      • Kirpalani P.A.
      • In Y.
      • Choi N.Y.
      • et al.
      Two-stage total knee arthroplasty for non-salvageable septic arthritis in diabetes mellitus patients.
      ,
      • Nazarian D.G.
      • Jesus D de
      • McGuigan F.
      • Booth R.E.
      A two-stage approach to primary knee arthroplasty in the infected arthritic knee.
      ]. The PJI literature has demonstrated articulating spacers to be superior [
      • Nahhas C.R.
      • Chalmers P.N.
      • Parvizi J.
      • et al.
      A randomized trial of static and articulating spacers for the treatment of infection following total knee arthroplasty.
      ,
      • Spivey J.C.
      • Guild G.N.
      • Scuderi G.R.
      Use of articulating spacer technique in revision total knee arthroplasty complicated by sepsis: a systematic meta-analysis.
      ] and supports using articulating spacers whenever the remaining bone and soft tissue allow. The use of single-stage metal-on-poly (MOP), or functional prosthetic, spacers for PJI has become more common with encouraging results [
      • Spivey J.C.
      • Guild G.N.
      • Scuderi G.R.
      Use of articulating spacer technique in revision total knee arthroplasty complicated by sepsis: a systematic meta-analysis.
      ,
      • Siddiqi A.
      • Nace J.
      • George N.E.
      • et al.
      Primary total knee arthroplasty implants as functional prosthetic spacers for definitive management of periprosthetic joint infection: a multicenter study.
      ], yet there are no reports of this technique used to treat septic native arthritic knees. We present outcomes of patients treated with a one-stage functional prosthetic spacer compared with those who received a two-stage treatment.

      Material and methods

      After obtaining institutional review board approval, an institutional database was queried to identify patients with infected, arthritic knees who were treated with placement of an antibiotic prosthesis between 1998 and 2019 at an academic, tertiary care medical center. Initial procedure of “placement of antibiotic spacer, knee” was used as the search criteria. Thorough analysis of each patient’s medical records and radiographs was performed to rule out other diagnoses and procedures. In all, 16 of the originally identified 600 patients were included; the other 584 patients represented patients who underwent explant and spacer placement for PJI after primary total knee arthroplasty (TKA) performed at an outside institution. The clinical records were retrospectively reviewed for demographic information, infection details, antibiotic treatment, complications, reoperations, revisions, and clinical outcomes. Clinical outcome scores were measured using Knee Society scores (KSS), Timed-Up-and-Go (TUG), visual analog score (VAS) for pain, and range of motion at final follow-up.
      Sixteen patients met inclusion criteria: 5 females (31%) and 11 males (69%), with a mean age of 64.2 ± 11.3 years and a mean body mass index of 26.3 ± 3.8 kg/m2 (Table 1, Table 2). A comparison of comorbidity burden between the 2 groups can be found in Figure 1. To better stratify the overall health, limb status, and comorbidities, the patients were given scores based on the McPherson classification system with 2 (13%) grade II infections and 14 (87%) grade III infection (Table 3) [
      • McPherson E.J.
      • Woodson C.
      • Holtom P.
      • et al.
      Periprosthetic total hip infection: outcomes using a staging system.
      ]. Eight (50%) were grade A hosts, 6 (38%) were grade B hosts, and 2 (14%) patients were grade C hosts. One (6%) patient was extremity grade 1, 10 (63%) were extremity grade 2, and 5 (31%) were extremity grade 3.
      Table 1Demographic data.
      PatientLateralitySexAgeBMISurgical/infectious history
      1LeftMale7522.7
      • Femur and tibia fractures 1992 MCA s/p partial removal of tibial hardware
      • 2017 Staphylococcus aureus infection s/p removal of femur IMN and IV antibiotics
      2LeftMale7127.5
      • May 2018 CS injection into knee
      • June 2018 aspiration: Streptococcus viridens
      • June 2018 arthroscopic irrigation and debridement, PO keflex
      3LeftMale6326.6
      • Longstanding history of erosive arthritis
      • Acute development of swelling, pain, and elevated inflammatory markers
      4LeftMale4821.2
      • Diagnosed with disseminated coccidioidomycosis
      • Episodic painful effusions since 2003
      5RightMale4920.1
      • August 2008: knee arthroscopy c/b persistent pain and effusion
      • February 2009: distal femur/proximal tibia osteomyelitis, septic arthritis diagnosed by aspiration
      6LeftFemale6025.8
      • August 2009: tibial plateau fracture s/p ORIF
      • October 2011: I&D and removal of hardware
      • Recurrent effusion and lab abnormalities
      7LeftFemale5534.1
      • April 2009: MRSA bacteremia during admission for ARDS
      • July 2009: multiple operative I&D left knee
      • August-October 2009: multiple operative I&D left knee
      • December 2009: diagnosed with postinfectious inflammatory arthropathy, abx discontinued
      • October 2011: repeat operative I&D for osteomyelitis proximal tibia and distal femur
      8RightMale7327.4
      • May 2009: right knee arthroscopy, open right fibular procedure
      • July 2011: admitted for septic shock
      9RightFemale6228.3
      • January 2008: right knee arthroscopy
      • April 2008: right knee arthroscopy aborted “tibial erosions”" seen, cx MSSA
      10RightFemale8525.4
      • 2007: right tibial plateau fracture s/p ORIF
      • May 2010: worsening knee pain, hardware prominence
      • June 2010: I&D right knee, ROH
      • September 2010: right knee acute swelling, aspiration cx MSSA
      11LeftMale7121.5
      • 1965: knee dislocation with multiligamentous injury, distal 1/3 tibial shaft fracture treated nonop, subsequent posttraumatic arthritis
      • April 2016: I&D of native knee
      12LeftFemale5929.0
      • 2000: ACL, MCL, medial meniscus injury
      • 2001: ACL reconstruction
      • 2002: Revision ACL
      • 2003: Removal of hardware
      • Progressive instability, intermittent swelling
      13LeftMale6722.4
      • April 2016: CS injection in Belize
      • April 2016: I&D left knee via small medial and lateral arthrotomies (Belize)
      • April 2016: arthroscopic I&D (USA) ×2
      • Developed draining sinus, unable to bear weight
      14LeftMale4231.6
      • Multiple remote knee arthroscopy
      • Presented to ED with fever, swelling, pain ×4 days
      15RightMale7726.9
      • 2015-2016: Multiple right knee arthroscopic and open I&Ds without resolution of symptoms
      16RightMale7030.3
      • April 2015: native knee septic arthritis s/p I&D ×2
      • June 2015: repeat knee I&D
      ACL, anterior cruciate ligament; ARDS, acute respiratory distress syndrome; BMI, body mass index; c/b, complicated/by; CS, corticosteroid; ED, emergency department; I&D, irrigation and debridement; IMN, intramedullary nail; IV, intravenous; MCA, motorcycle accident; MCL, medial collateral ligament; MRSA, methicillin-resistant Staphylococcus aureus; MSSA, methicillin-sensitive Staphylococcus aureus; ORIF, open reduction internal fixation; PO, per oral; ROH, removal of hardware; s/p, status/post.
      Table 2Infectious data.
      PatientKnown organismPrespacer antibioticsDate of surgerySpacer typeOR culturesPostspacer antibioticsTreatment durationInfection recurrenceChronic oral suppression
      1MRSAIV cefazolin11/3/17StaticNo growthPO cephalexin14 dNoNone
      2Streptococcus viridensPO cephalexin9/28/18StaticNo growthIV vancomycin42 dNoNone
      3NANone9/22/19StaticMRSAIV vancomycin15 dNoNone
      PO doxycycline23 d
      PO trimethoprim/ sulfamethoxazole3 d
      PO clindamycin33 d
      4CoccidioidesPO fluconazole10/28/10StaticCoccidioidesPO fluconazole25 dNoYes
      On chronic oral fluconazole for disseminated coccidioidomycosis before placement of knee spacer.
      PO itraconazole42 d
      PO fluconazole258 d
      5MSSAPO trimethoprim/ sulfamethoxazole3/4/09StaticMSSAIV vancomycin1 dNoNone
      IV nafcillin63 d
      IV vancomycin/IV zosyn4 d
      IV daptomycin60 d
      6Staphylococcus lugdunensisPO cephalexin3/22/12StaticStaphylococcus lugdunensisIV ceftaroline/IV zosyn
      Antibiotic therapy after static spacer exchange.
      61 d
      Antibiotic therapy after static spacer exchange.
      NoNone
      Oct 2011:2009: IV vancomycin 2011: IVIV daptomycin73 d
      7Staphylococcus epidermidisDaptomycin and PO rifampin4/4/12StaticNo growthPO trimethoprim/ sulfamethoxazole50 dNoNone
      8NANone1/12/12StaticNo growthIV daptomycin/PO ciprofloxacin22 dNoNone
      IV ceftaroline91 d
      9MSSAIV vancomycin PO Bactrim12/23/08StaticNo growthIV vancomycin/IV zosyn3 dNoNone
      IV cefazolin/PO rifampin43 d
      10MSSAIV vancomycin/IV nafcillin/IV cefazolin9/10/10StaticMSSAIV vancomycin76 dNoNone
      11Group C/G StreptococcusNone5/13/16Functional prostheticNo growthIV ceftriaxone54 dNoNone
      12NANone11/3/16Functional prostheticNo growthIV vancomycin/IV zosyn20 dNoNone
      13Enterobacter cloacaeIV ertapenem/PO ciprofloxacin5/24/16Functional prostheticNo growthIV ertapenem42 dNoNone
      14Group B StreptococcusNone6/22/19Functional prostheticNo growthIV ceftriaxone33 dNoNone
      PO clindamycin11 d
      IV cefazolin3 d
      15MSSAIV cefazolin8/15/16Functional prostheticCoagulase negative Staphylococcus
      Culture result and antibiotic therapy after conversion of functional prosthetic to static spacer.
      IV vancomycin
      Culture result and antibiotic therapy after conversion of functional prosthetic to static spacer.
      36 d
      Culture result and antibiotic therapy after conversion of functional prosthetic to static spacer.
      YesNone
      IV daptomycin
      Culture result and antibiotic therapy after conversion of functional prosthetic to static spacer.
      14 d
      Culture result and antibiotic therapy after conversion of functional prosthetic to static spacer.
      16MRSAIV vancomycin10/1/15Functional prostheticNo growthIV vancomycin42 dNoNone
      IV, intravenous; MRSA, methicillin-resistant Staphylococcus aureus; MSSA, methicillin-sensitive Staphylococcus aureus; NA, not available; PO, per oral; OR, operating room.
      a On chronic oral fluconazole for disseminated coccidioidomycosis before placement of knee spacer.
      b Antibiotic therapy after static spacer exchange.
      c Culture result and antibiotic therapy after conversion of functional prosthetic to static spacer.
      Figure thumbnail gr1
      Figure 1Comparison of comorbidity burden by spacer type demonstrating higher overall prevalence of medical comorbidities.
      Table 3McPherson patient classification
      PatientInfection gradeHost gradeExtremity grade
      1IIIAC
      2IIIAB
      3IIBB
      4IIICB
      5IIIAB
      6IIIBC
      7IIIBB
      8IIIBB
      9IIIBB
      10IIIBC
      11IIIAB
      12IIIAC
      13IIIAC
      14IIAA
      15IIIAB
      16IIICB
      The identified patients were treated by one of 2 methods: a two-stage protocol with a static antibiotic spacer followed by TKA vs formal arthrodesis, or a single-stage protocol with a functional prosthetic spacer. Surgeries were performed by one of 3 surgeons fellowship-trained in hip and knee arthroplasty (two-stage: J.I.H., S.B.G.; one-stage: D.F.A.). Spacer type was chosen by surgeon preference. Ten (63%) patients received 2-stage treatment consisting of thorough irrigation and debridement, distal femur and proximal tibial bone resection, and placement of a static antibiotic cement spacer. Patients were kept toe touch-weight-bearing while the static spacer was in place. Six (38%) patients received one-stage treatment, consisting of irrigation and debridement, primary TKA bone cuts, and implantation of a functional prosthetic spacer: a cobalt chrome primary TKA femoral component and an all-poly tibial component (Triathlon knee system; Stryker, Mahwah, NJ). TKA components were cemented according to pressurized third-generation cement technique. No additional hardware was used to augment the spacer fixation. For all patients, each bag of cement was augmented by organism-specific antibiotic agents or broad-spectrum antibiotics. The ratio of antibiotics to cement was chosen according to surgeon preference and was not standardized among the 3 surgeons. Survivorship was compared for the two-stage and one-stage procedures. Endpoints were defined as unplanned return to the operating room for any reason related to the affected joint and recurrence of infection as defined according to the 2018 Musculoskeletal Infection Society Guidelines [
      • Parvizi J.
      • Tan T.L.
      • Goswami K.
      • et al.
      The 2018 definition of periprosthetic hip and knee infection: an Evidence-based and Validated criteria.
      ].
      Continuous data are presented as mean and standard deviation. Categorical data are presented as number and percent. Kaplan-Meier survivorship curves were constructed to estimate the survivorship free of revision or reoperation [
      • Bland J.M.
      • Altman D.G.
      Survival probabilities (the Kaplan meier method).
      ]. To estimate survivorship at 1 and 3 years, 95% confidence intervals (CI) were added. Statistical significance was set at a P value of .05.

      Results

      One patient (6%) was infected with a fungal organism. Twelve patients (75%) had bacterial organisms diagnosed before spacer placement; of these 12, 10 received prior antibiotic therapy (83%). Nine patients (56%) never had growth of any organism from operating room cultures at the time of spacer placement. Two patients (13%) never had an organism identified at any point in their clinical course, including aspirations and operative cultures from procedures before spacer placement. One patient (6%) had a different organism identified at the time of spacer placement compared with what was identified at the time of prior unsuccessful debridement at an outside facility. Of the patients with identified bacteria, 2 had methicillin-sensitive Staphylococcus aureus (13%), one had methicillin-resistant Staphylococcus aureus (6%), one had group B Streptococcus (6%), and one had group C/G Streptococcus (6%; Table 2).
      Fourteen patients (88%) were treated with intravenous antibiotics after spacer placement. One patient received an oral antibiotic (6%), and one received an oral antifungal agent (6%). Therapy was directed by an infectious disease fellowship-trained physician (S.K.). One patient (6%) resumed his chronic suppressive therapy for disseminated coccidioidomycosis after second-stage surgery. No additional patients were placed on long-term oral antibiotic suppression therapy (Table 2).
      In the static spacer group, one patient (10%) never had a second-stage procedure. The survivorship free of any revision was 100% (CI: 100%-100%) for the 9 (90%) patients who went on to second-stage surgery at both 1 and 3 years. No patient has required reoperation at mean follow-up 7 ± 3.2 years (Fig. 2). Of those who have had second-stage procedures, 3 (33%) underwent arthrodesis, and 6 (67%) went on to the second-stage TKA at mean 159 days after the index surgery. The 3 patients who received arthrodesis had extensive bone and/or soft tissue deficiencies identified during spacer placement. No patient had a static spacer dislodge. Of those 3 patients, one was noted to have an extensor mechanism disruption at the time of initial spacer placement. This patient and one other both had a prior history of periarticular trauma about the knee and associated bone loss. The third patient had disseminated coccidioidomycosis affecting the knee and longstanding bone and soft tissue destruction before spacer placement. One patient who ultimately received the second-stage required repeat irrigation and debridement and spacer exchange; at the time of initially planned reimplantation, the tissue appearance was concerning for persistent infection, and the decision was made intraoperatively to abort the planned reimplantation. Of the 6 patients who went on to the second stage, one (17%) received primary posterior-stabilized implants (Zimmer-Biomet, Warsaw, IN). The rest (83%) received stemmed implants with varus-valgus constraint (LCCK; Zimmer-Biomet, Warsaw, IN).
      Figure thumbnail gr2
      Figure 2Survivorship curve of final implants in both cohorts demonstrating 100% survivorship of the second stage and arthrodesis at final follow-up and 86% survivorship of single-stage functional prosthetic spacers at final follow-up.
      The patient (10%) in the 2-stage group who never had a second procedure developed PJI in the contralateral knee with a draining sinus and extensor mechanism disruption. This patient also has significant bilateral lower extremity weakness due to cervical spinal cord compression. Further treatment of the knee with the primary static spacer has been deferred in light of this complicated situation.
      In the group that received one-stage functional prosthetic spacers, the survivorship free of any revision was 83% (CI: 82%-89%) at both 1 and 3 years (Fig. 2). The one patient (17%) who required additional surgery had persistent drainage after functional spacer placement. This patient was taken back to the operating room 16 days later for implant removal, repeat irrigation and debridement, and static spacer placement. Once the infection was cleared, 200 days after index spacer placement, the patient underwent spacer explant, irrigation and debridement, and placement of a rotating hinge prothesis (Stryker, Mahwah, NJ). This patient later sustained a fall that disputed the extensor mechanism and subsequently underwent mesh reconstruction (Marlex; CR Bard, Murray Hill, NJ) [
      • Abdel M.P.
      • Salib C.G.
      • Mara K.C.
      • et al.
      Extensor mechanism reconstruction with use of marlex mesh: a series study of 77 total knee arthroplasties.
      ,
      • Browne J.A.
      • Hanssen A.D.
      Reconstruction of patellar tendon disruption after total knee arthroplasty: results of a new technique utilizing synthetic mesh.
      ] 403 days after index spacer placement.
      One patient in the one-stage functional prosthetic spacer group developed a nonhealing wound on the ipsilateral distal tibia. Pathological examination demonstrated that the wound had transformed into squamous cell carcinoma. This lesion has now been resected to negative margins, and required microvascular reconstruction with free gracilis muscle transfer and associated split-thickness skin graft. The knee has remained asymptomatic and is functioning well.
      For all patients, the mean VAS was 0.6 ± 0.93. Stratifying the two-stage and functional prosthetic groups demonstrated a mean VAS of 0.4 ± 0.8 for the two-stage group and a mean VAS of 0.8 ± 1.07 for the one-stage functional prosthetic group (P = .450). Three patients of the 12 (25%) who received an articulating prosthesis had flexion contractures at final postoperative follow-up. Two patients in the two-stage group had flexion contracture equal to 10°, and one patient in the one-stage functional prosthetic spacer group had a flexion contracture of 20° (Incidentally, this patient failed one-stage functional prosthetic spacer placement.). The mean terminal flexion for all 12 patients with articulating prostheses was 101 ± 22°, 96 ± 27° in the two-stage group, and 107 ± 14° in the one-stage functional prosthetic spacer group (P = .449; Table 4).
      Table 4Outcome scores
      All values reported as means except for flexion contracture, which is reported as number of patients.
      VASFlexion contractureTerminal flexionKSSTUG (sec)
      Two-Stage0.48222
       TKA0.72/696°8920
       Arthrodesis0----7224
      Functional Prosthetic0.81/6107°8411.5
      Total0.63/12101.5°8317.8
      TKA, total knee arthroplasty, VAS, visual analog scale; KSS, Knee Society score; TUG, timed up-and-go.
      All values reported as means except for flexion contracture, which is reported as number of patients.
      Considering all patients, the mean KSS was 83 ± 13. The mean KSS for the two-stage group was 82 ± 12. Within the two-stage group, the mean KSS for the 3 patients (30%) with formal arthrodesis and the one patient (10%) with retained static spacer was 72 ± 6, and the mean KSS for the 6 patients (60%) with the second stage was 89 ± 10. In the one-stage functional prosthetic spacer group, the mean KSS was 84 ± 15. The patient who required further surgery reported a KSS of 52; the mean KSS considering only patients with retained functional spacers was 91 ± 6 (Table 4). There was no statistically significant difference between Knee Society scores when comparing the 2-stage and one-stage groups as a whole (P = .766).
      The mean TUG time for all the patients was 18 ± 10 seconds. For all patients who received two-stage treatment, the mean TUG time was 22 ± 10 seconds. The mean TUG time for the arthrodesis and retained static spacer patients (40%) was 24 ± 4 seconds, and the mean TUG time for the two-stage TKA patients (60%) was 20 ± 12 seconds (P = .615). The mean TUG time for patients with retained one-stage functional prosthetic spacers (83%) was 9 ± 3 seconds. The patient who failed one-stage functional prosthetic spacer reported a TUG time of 26 seconds (Table 4). Comparing the patients with retained functional prosthetic spacer with those who received two-stage TKA, there was a trend toward faster mean TUG time, but this was not statistically significant (P = .087).

      Discussion

      Treatment of advanced knee arthritis in the setting of infection is a clinical challenge. The mainstays of treatment for infection in the nonarthritic knee (surgical debridement, lavage, and intravenous antibiotics) do not sufficiently address any resulting cartilage damage or deformity [
      • Schröder J.H.
      • Krüger D.
      • Perka C.
      • Hufeland M.
      Arthroscopic treatment for primary septic arthritis of the hip in adults.
      ,
      • Aïm F.
      • Delambre J.
      • Bauer T.
      • Hardy P.
      Efficacy of an arthroscopic treatment for resolving infection in septic arthritis of native joints.
      ,
      • Elsissy J.G.
      • Liu J.N.
      • Wilton P.J.
      • et al.
      Bacterial septic arthritis of the adult native knee joint.
      ]. Although this situation is rare compared to the frequency of PJI, it is important to optimize treatment for these patients, as patients with a history of infection about the knee are often more likely to develop PJI after primary TKA, especially if infectious treatment history information is limited [
      • Seo J.G.
      • Moon Y.W.
      • Park S.H.
      • et al.
      Primary total knee arthroplasty in infection sequelae about the native knee.
      ,
      • Jerry G.J.
      • Rand J.A.
      • Ilstrup D.
      Old sepsis prior to total knee arthroplasty.
      ,
      • Sultan A.A.
      • Mahmood B.
      • Samuel L.T.
      • et al.
      Patients with a history of treated septic arthritis are at high risk of periprosthetic joint infection after total joint arthroplasty.
      ,
      • Bae D.K.
      • Yoon K.H.
      • Kim H.S.
      • Song S.J.
      Total knee arthroplasty in stiff knees after previous infection.
      ,
      • Lee G.-C.
      • Pagnano M.W.
      • Hanssen A.D.
      Total knee arthroplasty after prior bone or joint sepsis about the knee.
      ].
      Our data show that both two-stage protocol with a static spacer and single-stage protocol with a functional prosthetic spacer are acceptable treatment options for this population. By the Delphi criteria [
      • Diaz-Ledesma C.
      • Higuera C.A.
      • Parvizi J.
      Success after treatment of periprosthetic joint infection: a Delphi-based international multidisciplinary consensus.
      ], successful treatment of infection was achieved in 100% (9/9) of patients who received two-stage treatment and in 83% (5/6) who received one-stage treatment. The one-stage functional prosthetic spacer has demonstrated excellent survivorship in the limited series of patients that received it. The patient who failed treatment with one-stage functional prosthetic spacer failed early because of inadequate treatment of infection, rather than failing late because of mechanical reasons. The single-stage patients trended toward greater terminal flexion and a faster TUG test. KSSs were similar for patients who received a single-stage spacer and two-stage TKA. The reported KSSs were similar to those reported by other authors for patients with infection in the native arthritic knee [
      • Seo J.G.
      • Moon Y.W.
      • Park S.H.
      • et al.
      Primary total knee arthroplasty in infection sequelae about the native knee.
      ,
      • Shaikh A.A.
      • Ha C.-W.
      • Park Y.-G.
      • Park Y.-B.
      Two-stage approach to primary TKA in infected arthritic knees using intraoperatively molded articulating cement spacers.
      ,
      • Nazarian D.G.
      • Jesus D de
      • McGuigan F.
      • Booth R.E.
      A two-stage approach to primary knee arthroplasty in the infected arthritic knee.
      ] and also similar to those reported for patients after treatment for PJI [
      • Fehring T.K.
      • Odum S.
      • Calton T.F.
      • Mason J.B.
      Articulating versus static spacers in revision total knee arthroplasty for sepsis.
      ,
      • Freeman M.G.
      • Fehring T.K.
      • Odum S.M.
      • et al.
      Functional advantage of articulating versus static spacers in 2-stage revision for total knee arthroplasty infection.
      ].
      Classically, this patient population has been treated with 2-stage arthroplasty [
      • Shaikh A.A.
      • Ha C.-W.
      • Park Y.-G.
      • Park Y.-B.
      Two-stage approach to primary TKA in infected arthritic knees using intraoperatively molded articulating cement spacers.
      ,
      • Kirpalani P.A.
      • In Y.
      • Choi N.Y.
      • et al.
      Two-stage total knee arthroplasty for non-salvageable septic arthritis in diabetes mellitus patients.
      ,
      • Nazarian D.G.
      • Jesus D de
      • McGuigan F.
      • Booth R.E.
      A two-stage approach to primary knee arthroplasty in the infected arthritic knee.
      ,
      • Mirza A.H.
      • Noble J.
      • Teanby D.
      Infected knee treated by total knee arthroplasty.
      ,
      • Hochreiter B.
      • Strahm C.
      • Behrend H.
      Short-interval two-stage approach to primary total knee arthroplasty for acutely septic osteoarthritic knees.
      ]. Indeed, in our series, the patients who received two-stage treatment have demonstrated a 100% survivorship rate. There have also been reports of successful treatment using a one-stage approach [
      • Jerry G.J.
      • Rand J.A.
      • Ilstrup D.
      Old sepsis prior to total knee arthroplasty.
      ,
      • Bae D.K.
      • Yoon K.H.
      • Kim H.S.
      • Song S.J.
      Total knee arthroplasty in stiff knees after previous infection.
      ,
      • Lee G.-C.
      • Pagnano M.W.
      • Hanssen A.D.
      Total knee arthroplasty after prior bone or joint sepsis about the knee.
      ,
      • Bauer T.
      • Lacoste S.
      • Lhotellier L.
      • et al.
      Arthroplasty following a septic arthritis history: a 53 cases series.
      ,
      • Jupiter J.B.
      • Karchmer A.W.
      • Lowell J.D.
      • Harris W.H.
      Total hip arthroplasty in the treatment of adult hips with current or quiescent sepsis.
      ]. Similar to the patients in the cohort studied by Bauer et al. [
      • Bauer T.
      • Lacoste S.
      • Lhotellier L.
      • et al.
      Arthroplasty following a septic arthritis history: a 53 cases series.
      ], our patient population included those with quiescent and evolutive infections. Treatment protocols were determined as per surgeon preference, rather than by infection chronicity, which led both types of patients treated according to both protocols. Our results indicate that one-stage arthroplasty using a functional prosthetic spacer is an acceptable treatment for both evolutive and quiescent infections.
      A recent multicenter randomized controlled trial of articulating and static cement spacers found articulating spacers to be associated with improved outcomes in the treatment of PJI after TKA [
      • Nahhas C.R.
      • Chalmers P.N.
      • Parvizi J.
      • et al.
      A randomized trial of static and articulating spacers for the treatment of infection following total knee arthroplasty.
      ]. Compared with articulating cement spacers, the use of functional prosthetic spacers allows infection to be treated in a single stage, which is particularly attractive for patients with a septic process about a native, arthritic knee. Functional prosthetic spacers have been shown to be effective for treatment of PJI [
      • Spivey J.C.
      • Guild G.N.
      • Scuderi G.R.
      Use of articulating spacer technique in revision total knee arthroplasty complicated by sepsis: a systematic meta-analysis.
      ,
      • Siddiqi A.
      • Nace J.
      • George N.E.
      • et al.
      Primary total knee arthroplasty implants as functional prosthetic spacers for definitive management of periprosthetic joint infection: a multicenter study.
      ,
      • Marson B.A.
      • Walters S.T.
      • Block B.V.
      • Sehat K.
      Two-stage revision surgery for infected total knee replacements: reasonable function and high success rate with the use of primary knee replacement implants as temporary spacers.
      ,
      • Siddiqi A.
      • George N.E.
      • White P.B.
      • et al.
      Articulating spacers as a modified one-stage revision total knee arthroplasty: a preliminary analysis.
      ,
      • Petis S.M.
      • Perry K.I.
      • Pagnano M.W.
      • et al.
      Retained antibiotic spacers after total hip and knee arthroplasty resections: high complication rates.
      ,
      • Choi H.R.
      • Freiberg A.A.
      • Malchau H.
      • et al.
      The fate of unplanned retention of prosthetic articulating spacers for infected total hip and total knee arthroplasty.
      ]. The described benefits of this protocol compared with traditional two-stage approach include lessened patient morbidity, earlier mobility, and potential for decreased costs [
      • Marson B.A.
      • Walters S.T.
      • Block B.V.
      • Sehat K.
      Two-stage revision surgery for infected total knee replacements: reasonable function and high success rate with the use of primary knee replacement implants as temporary spacers.
      ,
      • Kallala R.F.
      • Vanhegan I.S.
      • Ibrahim M.S.
      • et al.
      Financial analysis of revision knee surgery based on NHS tariffs and hospital costs: does it pay to provide a revision service?.
      ,
      • Kim T.W.
      • Makani A.
      • Choudhury R.
      • et al.
      Patient-reported activity levels after successful treatment of infected total knee arthroplasty.
      ,
      • Gomez M.
      • Tan T.
      • Manrique J.
      • et al.
      The fate of spacers in the treatment of periprosthetic joint infection.
      ,
      • Nagra N.S.
      • Hamilton T.W.
      • Ganatra S.
      • et al.
      One-stage versus two-stage exchange arthroplasty for infected total knee arthroplasty: a systematic review.
      ]. However, several prior studies have reported mixed results on retained spacers placed with highly concentrated antibiotic cement. A retrospective review by Petis et al. [
      • Petis S.M.
      • Perry K.I.
      • Pagnano M.W.
      • et al.
      Retained antibiotic spacers after total hip and knee arthroplasty resections: high complication rates.
      ] found a 21% cumulative revision rate for retained knee spacers at 2-year follow-up. Choi et al. [
      • Choi H.R.
      • Freiberg A.A.
      • Malchau H.
      • et al.
      The fate of unplanned retention of prosthetic articulating spacers for infected total hip and total knee arthroplasty.
      ] reported 83% success rate for unplanned spacer retention at a mean follow-up of 43 months, and reasons cited for retention were satisfaction with pain and level of function. Siddiqi et al. [
      • Siddiqi A.
      • Nace J.
      • George N.E.
      • et al.
      Primary total knee arthroplasty implants as functional prosthetic spacers for definitive management of periprosthetic joint infection: a multicenter study.
      ] demonstrated that a single-stage treatment with functional prosthetic spacer was not inferior to traditional two-stage treatment for PJI considering infection clearance, reoperation, and overall success rates.
      The 3 patients who received two-stage treatment with eventual arthrodesis represent the patients with the most severe combined soft tissue and bony deficits. In our series, they reported minimal pain but lower KSS and slower TUG than the patients who received articulating implants. The mean pain scores and KSS reported in our series were superior to what were reported in the literature [
      • Robinson M.
      • Piponov H.I.
      • Ormseth A.
      • et al.
      Knee arthrodesis outcomes after infected total knee arthroplasty and failure of two-stage revision with an antibiotic cement spacer.
      ], perhaps reflecting that the patients in our cohort had fewer total surgical procedures than those who had arthrodesis procedures after failing two-stage treatment for PJI recurrence [
      • Robinson M.
      • Piponov H.I.
      • Ormseth A.
      • et al.
      Knee arthrodesis outcomes after infected total knee arthroplasty and failure of two-stage revision with an antibiotic cement spacer.
      ].
      This study is not without limitations. First, this study represents a small series of patients. The studied patients do represent an uncommon clinical situation and include all who were treated at our institution over a 20-year period. We attempted to mitigate this issue by reporting on means and trends in the data, rather than assigning definitive statistical significance. In addition, most patients included in this study were initially treated at outside institutions, and detailed surgical data, culture reports, and antibiotic therapy records before treatment at our institution were often incomplete or unavailable. Thus, we are unable to make specific comments about the role of antibiotic therapy agents or treatment duration in the management of these patients. Finally, the short follow-up for the functional spacer cohort precludes us from commenting on the cost-effectiveness of this treatment, as we cannot predict which of these patients will need revision in the future.

      Conclusions

      This is the first report of functional prosthetic spacers used in the treatment of infection about the native degenerative knee. Our results indicate that one-stage functional spacers are not inferior to the gold-standard two-stage treatment. Our data indicate that patients who are successfully treated with one-stage functional prosthetic spacers may have superior functional ability indistinguishable from a reimplanted knee replacement after treatment. Further study of a larger cohort of these complex patients with longer follow-up is needed to corroborate our findings.

      Conflict of interest

      J. I. Huddleston is in the editorial/governing board of Journal of Arthroplasty and is a board member/made committee appointments for AAHKS. S. B. Goodman is in the speakers' bureau of/gave paid presentations for Merck; is a paid consultant for Depuy Synthes Joint Reconstruction, J&J Medical Device Companies, Pluristem, Wishbone, and Volt Medical; has stock or stock options in Accelalox and Arquos; is in the editorial/governing board of Journal of Arthroplasty, Journal of Orthopedic Research, and Biomaterials; and is a board member in/made committee appointments for Journal of Orthopedic Research and Biomaterials. D. F. Amanatullah is a paid consultant for Exactech, Stryker, Zimmer-Biomet, Depuy, QT Ultrasound, Recoup Fitness, Bullseye, and Radial Medical; received research support from Stryker, Roam Robotics, and Sparta Health Sciences; received royalties, financial, or material support from Medscape; and is in the editorial/governing board of Journal of Arthroplasty.
      For full disclosure statements refer to https://doi.org/10.1016/j.artd.2021.01.009.

      Acknowledgment

      The authors would like to thank Gina A. Suh, M.D., for her treatment of these complex patients during her time as an assistant clinical professor in the Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University.
      Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

      Appendix A. Supplementary data

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