Abdel, Matthew P.

Background: Infection following extensor mechanism reconstruction (EMR) with Marlex mesh (C.R. Bard) is devastating and limb-threatening. The purpose of this study was to evaluate whether vancomycin-loaded mesh reduces staphylococcal infection in a murine EMR model. Methods: Mouse-sized, 8-layer mesh constructs were fabricated to simulate clinical reconstruction and soaked in a vancomycin solution (50 mg/mL) for in vitro and in vivo testing. Three methicillin-resistant clinical isolates from human periprosthetic Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus lugdunensis knee infections were evaluated. In vitro testing assessed vancomycin loading capacity, mechanical properties, antibacterial activity, and inhibition of biofilm formation. For in vivo experiments, plain or vancomycin-loaded mesh was implanted into C57BL/6 mouse extensor mechanisms, which were intraoperatively contaminated with 1 of the 3 study isolates (5 per group). Mesh and surrounding tissue were harvested for quantitative culture on postoperative day 9. Results: For all 3 isolates, vancomycin-loaded mesh produced zones of inhibition and exhibited antibacterial activity through at least 3 days in vitro (p < 0.0001). Mechanical testing revealed that loading mesh with vancomycin did not negatively impact tensile strength, hysteresis, or suture pull-through properties. In vitro testing of inhibition of biofilm formation demonstrated reduced colony-forming units 6 hours after inoculation, which remained low throughout the 9-day experimental period (p < 0.05 for all isolates). In vivo, vancomycin-loaded mesh reduced bacterial burden on mesh and in surrounding tissue by >3 log 10 compared with plain mesh for all 3 isolates (p < 0.01 for both mesh and tissue). Conclusions: Vancomycin-loaded mesh provided in vitro antibacterial activity without compromising mesh mechanical properties and reduced staphylococcal infection in a murine EMR model. Further work is needed to evaluate translational potential and safety before clinical application. Clinical Relevance: Mesh-associated infection after EMR is devastating and difficult to treat. These preclinical findings suggest that local vancomycin delivery may serve as an adjunct to systemic prophylaxis, warranting further study before clinical use.

Aims Two-stage exchange arthroplasty with an antibiotic-eluting cement spacer remains the predominant strategy in the USA for managing chronic periprosthetic joint infection (PJI) following total hip arthroplasty (THA). The aim of this study was to evaluate a commercially available, partially intraoperatively fabricated articulating high-dose antibiotic cement spacer, focusing on survival, complications, and patient-reported outcomes. Methods A total of 298 patients (302 THAs) underwent two-stage exchange arthroplasty for PJI using a specific articulating antibiotic spacer between August 2005 and May 2022. Patients with a previous failed two-stage exchange were excluded, although 121 THAs (302, 40%) had undergone previous PJI-related procedures. The mean age of the patients was 65 years (SD 11), the mean BMI was 32 kg/m 2 (SD 7), and 116 (38%) were female. Most patients were classified as McPherson host B (158; 52%) and limb grade 2 (165; 55%), and 265 (88%) met the 2011 Musculoskeletal Infection Society criteria. The mean follow-up was six years (2 to 16). Results At five years after reimplantation, survival free of reinfection, aseptic rerevision, any rerevision, or any reoperation were 89% (95% CI 85.2 to 93.1), 93% (95% CI 89.3 to 96.1), 86% (95% CI 81.3 to 90.3), and 80% (95% CI 74.7 to 84.9), respectively. Dislocation accounted for most aseptic rerevisions (15/20). McPherson host C (HR 3.7 (95% CI 1.4 to 9.6); p = 0.007) and limb grade 3 (HR 3.3 (95% CI 1.0 to 11.1); p = 0.049) were significantly associated with an increased risk of reinfection. The mean Harris Hip Score at the latest follow-up was 76 (29 to 100). A total of 17 patients underwent revision or removal of a spacer for concerns about persistent infection and two for dislocation of the spacer. Eight patients underwent a non-rerevision reoperation during the spacer interval for wound drainage (n = 5), dislocation of the spacer (n = 2), and perispacer fracture (n = 1). A total of 26 spacer-related complications were treated nonoperatively (15 perispacer fractures, 11 dislocations). Dislocation of the spacer was strongly associated with dislocation after reimplantation (HR 6.2 (95% CI 2.3 to 16.9); p < 0.001). Conclusion This commercially available, partially intraoperatively fabricated articulating spacer showed excellent reinfection-free five-year survival (89%). Spacer-related fracture and dislocation each occurred in 5% of patients. Dislocation of the spacer significantly increased the risk of dislocation following reimplantation, supporting the use of higher-stability bearings in these high-risk patients. Cite this article: Bone Joint J 2026;108-B(9):1104–1112.

Aims Extensor mechanism disruption is a major complication following total knee arthroplasty, with treatment often consisting of extensor mechanism reconstruction utilizing monofilament polypropylene mesh (Marlex mesh, C. R. Bard, Inc). Infection following this procedure is devastating, often resulting in revision surgery and mesh removal, with permanent limb dysfunction. This study evaluated the in vitro ability of vancomycin-loaded polypropylene mesh to inhibit growth of isolates of three Staphylococcus species from patients with periprosthetic joint infection. Methods The mesh was prepared in two configurations – single-layer and eight-layer – and soaked for ten minutes in either sterile water (control) or vancomycin solution (50 mg/ml), after which the mesh was placed on tryptic soy agar plates inoculated with staphylococci and incubated at 37°C for 18 to 24 hours. Zones of inhibition were measured daily over seven days, with mesh transferred to freshly inoculated plates daily. Testing was performed in triplicate, with experiments repeated three times for each bacterial isolate. A total of 30 clinical isolates were tested (five methicillin-susceptible Staphylococcus epidermidis , five methicillin-resistant S. epidermidis , ten methicillin-resistant Staphylococcus aureus , and ten Staphylococcus lugdunensis ). Results Across all species, the eight-layer vancomycin-loaded mesh produced statistically significantly larger median zones of inhibition than the single-layer mesh. The antibacterial activity of the eight-layer mesh persisted through to day 7, while the single-layer mesh showed reduced activity by days 4 to 5. Conclusion Compared with single-layer vancomycin-loaded mesh, multilayer vancomycin-loaded mesh, which mimics clinical application, provides enhanced and sustained antibacterial activity in vitro. Cite this article: Bone Joint Res 2026;15(8):998–1004.

We previously reported 5-year results of 57 patients with major acetabular defects (Paprosky 2B through 3B) who underwent full (31) or half (26) cup-cage reconstructions. This study provides an update with 8.8-year mean follow-up. The 10-year cumulative incidence of and survivorship free from revision, reoperation, and complications were estimated. The 10-year cumulative incidence of revision was 14% for full and 12% for half constructs. The incidence of revision for aseptic loosening was 4.3% and 4.6%, respectively. The 10-year survivorship free from aseptic loosening for patients with pelvic discontinuity was 88.9% (95% confidence interval [CI], 70.6% to 100%) and 85.7% (95% CI, 61.8% to 100%), respectively; no patient without pelvic discontinuity required revision for aseptic loosening. The 10-year cumulative incidence of complications was 42% for all patients, including a 15% incidence of dislocation. Thus, both full and half cup-cage constructs provided durable fixation for complex acetabular bone loss at 10 years, although dislocation remains a concern. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Background: Greater trochanteric (GT) fractures after total hip arthroplasty (THA) are typically managed nonoperatively. However, outcome data for patient counseling remain limited. We evaluated the nonoperative results, focusing on fracture union rates and the presence of persistent limp in relation with fracture location, displacement magnitude, and direction. Methods: We retrospectively reviewed 82 postoperative GT fractures not associated with trochanteric osteolysis following primary THA performed between 1984 and 2020. The mean follow-up was 9 years. Fracture location was classified relative to the contralateral lesser trochanter as tip, waist, or base. Initial displacement, migration, final displacement, and bony union were assessed radiographically. Clinical outcomes included the presence of a persistent limp and Harris Hip Score. Multivariable analyses were performed to identify factors associated with nonunion and limp. Results: Fractures were classified as tip (n = 32), waist (n = 29), or base (n = 21). The mean initial displacement was 8.9 mm, with 43% displaced >10 mm. Initial displacement was significantly lower in base fractures (4.8 mm) compared with tip (10.1 mm) or waist (10.8 mm) fractures (p < 0.05). The mean final displacement was 14.6 mm. 45% of fractures achieved complete bony union, and 38% of patients demonstrated a persistent limp. In multivariable analysis, greater final displacement (>12 mm), and tip and waist fractures were independently associated with nonunion. Posterior fracture displacement was significantly associated with persistent limp. Conclusions: Outcomes following nonoperative management of GT fractures after THA depend on fracture morphology and displacement characteristics. Tip and waist fractures and fractures with final displacement >12 mm have a higher risk of nonunion, whereas posterior and superior displacement is associated with persistent limp. Greater than 20 mm of displacement is associated with both limp and nonunion. These findings may assist surgeons in counseling patients and in identifying fracture patterns at higher risk for adverse outcomes of nonoperative management. Level of Evidence: Level III (Prognostic Study). See Instructions for Authors for a complete description of levels of evidence.

Aims Reliable assessment of joint stiffness is essential for studying arthrofibrosis in preclinical animal models. This study presents a new dedicated biomechanics device for measuring knee stiffness in mouse, rat, and rabbit models of arthrofibrosis, with the aim of validating its performance and comparing it to a previously validated device. Methods The new system integrates a torque load cell, stepper motor, and absolute encoder in a through-hole, unified configuration for precise continuous torque-angle measurement, with custom limb brackets ensuring species-specific alignment at the joint’s centre of rotation. To validate this device and compare it to a previously validated device, arthrofibrosis was induced using established models of extra-articular immobilization in mice and intra-articular violation with immobilization in rats and rabbits, followed by defined remobilization periods. Torque-angle curves were recorded ex vivo across species-specific torque ranges, and measurement variability between the new and a previous validated device was statistically compared using Brown-Forsythe’s test. Results The onset of hyperextension in contralateral limbs occurred at mean angles of 152.4° (mice), 154.4° (rats), and 152.8° (rabbits), and at maximum torque, mean flexion angles were 79.2°, 87.3°, and 140.5°, respectively. No significant differences in measurement variability were observed between devices across all species. Conclusion These findings demonstrate that our new device provides reproducible torque-angle data while maintaining the statistical robustness of the previous device and offering improved mechanical design and operational standardization. By enabling standardized, cross-species joint stiffness quantification, this platform improves cross-study comparability and strengthens the translational reliability of preclinical arthrofibrosis research. Cite this article: Bone Joint Res 2026;15(6):716–725.

Background: Contemporary rotating-hinge total knee arthroplasties (RH-TKAs) have shown reasonable short-term survivorship in smaller series, but concerns remain regarding risks of aseptic and septic failure. The purpose of this study was to assess outcomes of contemporary RH-TKAs in one of the largest series to date. Methods: We retrospectively identified 575 RH-TKAs (60% used for aseptic etiologies and 40% used during reimplantation in 2-stage treatment of periprosthetic joint infection [PJI]) from 2002 to 2021 at a single institution. The mean age was 67 years, 58% were female, and the mean body mass index was 33 kg/m 2 . Sixty-five percent had Anderson Orthopaedic Research Institute (AORI) type-2B or 3 bone loss. Kaplan-Meier survivorship analyses were performed. The mean follow-up was 6 years (range, 2 to 19 years). Results: Survivorship free from any revision was 76% at 5 years and 64% at 10 years. The most common revision indications were PJI (54%) and aseptic loosening (20%). RH-TKA used in the primary setting showed better survivorship compared with RH-TKA used during reimplantation after PJI (79% versus 60% at 10 years). Survivorship free from revision for aseptic loosening was 96% at 5 years and 90% at 10 years. Survivorship free from revision for PJI was 84% at 5 years and 81% at 10 years. Survivorship free from revision for PJI was even lower for RH-TKAs used during reimplantation, 74% at 5 years and 73% at 10 years. RH-TKA used during reimplantation in the treatment of PJI was associated with an increased risk of any revision (HR = 2, p < 0.001). Radiographic analysis of 425 knees that were not revised and had radiographs available for review showed that 6% of femoral components and 8% of tibial components had evidence of loosening at the time of final follow-up. The mean Knee Society Score improved from 33 to 69 at 2 years (p < 0.001). Conclusions: The 10-year survivorship free from aseptic loosening was 90% in this large series of RH-TKAs. This represents one of the best survivorships free from aseptic loosening published to date. Knees with prior PJI had markedly poorer survivorship than knees treated for aseptic etiologies, with double the risk of revision. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Background: Revision total hip arthroplasty (THA) rates are increasing, with instability, aseptic loosening, and infection identified as primary indications for surgery. Managing significant acetabular and femoral bone loss remains a complex challenge, requiring standardized classification systems to guide reconstruction strategies. Objective: This article reviews current surgical protocols and clinical outcomes for complex THA revisions, specifically focusing on the management of bone defects and periprosthetic fractures using techniques employed at the Mayo Clinic. Key Points: Preoperative evaluation must prioritize the exclusion of infection via inflammatory markers and joint aspiration. Acetabular reconstructions are categorized by the Paprosky classification; Type 3 defects often necessitate jumbo cups, porous tantalum augments, or custom triflange implants to achieve stability. In cases of pelvic discontinuity, tantalum cup-cage constructs or distraction techniques are utilized, showing high short-term survival despite risks of stress fractures or reduced bone stock. Femoral revisions utilize modular fluted tapered stems (TMFT) for Paprosky Type 3 and 4 defects, providing superior axial and longitudinal stability compared to cemented options. Extended lateral femoral osteotomy is frequently employed to facilitate component removal. Periprosthetic fractures are managed according to the Vancouver classification, with stable stems treated via internal fixation and loose stems requiring TMFT or proximal femoral replacement. Conclusion: Successful THA revision relies on meticulous preoperative planning and the selection of implants that ensure osseointegration and mechanical stability. The shift toward porous metal technology and modular femoral components has improved outcomes in cases of severe bone deficiency.

Aims Total knee arthroplasty (TKA) for end-stage osteonecrosis has historically been associated with concerns regarding aseptic loosening, and long-term data are limited. The purpose of this study was to update and expand our previous series with long-term follow-up, with specific emphasis on implant survivorship, risk factors for failure, complications, and clinical outcomes in a consecutive cohort of TKAs performed for primary and secondary osteonecrosis. Methods We retrospectively identified 295 consecutive TKAs in 266 patients for osteonecrosis performed at a single tertiary care academic institution from January 2002 to July 2022. Of these, 207 TKAs (70%) were performed for primary osteonecrosis, and 88 (30%) for secondary osteonecrosis. The predominant cause of secondary osteonecrosis was steroid use (59%; n = 52), followed by post-traumatic (25%; n = 22), radiation-induced (9%; n = 8), and alcohol-induced (7%; n = 6) osteonecrosis. Implant survivorship was analyzed as a time-to-event outcome using Kaplan-Meier estimation. The mean age was 61 years (18 to 93), with 67% being female (n = 197). The mean follow-up was nine years (2 to 20). Results The 15-year survivorship free of any revision for the entire cohort was 92% (95% CI 87 to 97), with similar rates between primary and secondary osteonecrosis (92% (95% CI 87 to 98) vs 93% (95% CI 87 to 100), respectively; p = 0.459). Varus-valgus constraint implant designs (HR 10.8 (95% CI 2.7 to 43.4); p < 0.001) and tibial stem use (HR 12.0 (95% CI 4.1 to 35.1); p < 0.001) were associated with an increased risk of any revision. The 15-year survivorship free of aseptic loosening was 97% (95% CI 93 to 100) for the entire cohort. Age under 65 years (HR 2.7 (95% CI 1.4 to 5.4); p = 0.005) and secondary osteonecrosis (HR 1.9 (95% CI 1.0 to 3.4); p = 0.044) were associated with an increased risk of any reoperation at 15 years. Conclusion TKA is a durable and reliable option for primary osteonecrosis at long-term follow-up. However, TKAs performed for secondary osteonecrosis carry a higher reoperation risk. Cite this article: Bone Joint J 2026;108-B(4):455–462.

Aims Data on revision of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) are limited by low patient numbers and short-term follow-up. This study evaluated the mid-term outcomes of revision of UKA to TKA focusing on implant survival, radiological results, and clinical outcomes in a large series. Methods We identified 235 revisions of UKA to TKA performed between 1995 and 2022 utilizing our institutional total joint registry. The mean age was 65 years (SD 10), mean BMI was 32 kg/m 2 (SD 6), and 50% were female (n = 118). The most common indications for revision were aseptic loosening (37%; n = 83), progression of arthritis in adjacent compartments (35%; n = 81), and unexplained pain (20%; n = 47). The mean time from UKA to revision to a TKA was four years (26 days to 15 years). Posterior-stabilized constructs were used in 78% of the revisions (n = 184), varus-valgus constrained implants in 14% (n = 33), and cruciate-retaining implants in 7% (n = 16). Metaphyseal fixation devices were used in 8% of cases (n = 18) and augments in 31% (n = 73). Kaplan-Meier implant survival analyses were performed, radiographs reviewed, and clinical outcomes were measured with Knee Society Scores (KSSs). Mean follow-up was eight years (2 to 25). Results The five-year survival free of any re-revision was 93% (95% CI 89 to 97). There were 17 further re-revisions with femoral and/or tibial aseptic loosening (n = 7), periprosthetic joint infection (n = 4), and stiffness (n = 2) being the most common indications. The five-year survival free of any reoperation was 87% (95% CI 83 to 92). Stiffness (n = 7) and unresurfaced patellar clunk/crepitus (n = 4) were the most common indications for reoperations without implant exchange. There were 25 nonoperative postoperative complications, most commonly stiffness (n = 5), flexion instability (n = 4), and haematoma (n = 4). No unrevised TKAs showed signs of radiological loosening. KSS function score improved from 54 (SD 18) to 69 (SD 26; p = 0.003). Conclusion In this large series of 235 revisions of UKA to TKA, the five-year survival of the TKAs free of re-revision was good. Our data suggest that the implant survival and clinical outcomes were inferior to primary TKA. Tibial component aseptic loosening was the most common reason for re-revision. Cite this article: Bone Joint J 2025;107-B(12):1281–1287.