Abdel, Matthew P

Background: Modular fluted tapered (MFT) femoral components are frequently utilized in aseptic revision total hip arthroplasties (THAs). However, long-term follow-up has been limited. The purpose of this study was to update our prior series at long-term follow-up, with specific emphasis on implant survivorship, radiographic results, and complications in a large cohort of aseptic revision THAs using MFT stems. Methods: We retrospectively identified 515 aseptic femoral revisions performed with 2 MFT stem designs in the total joint registry of a single tertiary care academic institution from 1999 to 2013. Serial radiographs were reviewed for subsidence of >5 mm. The mean follow-up (and standard deviation) was 10 ± 5 years (range, 2 to 21 years). A competing risk model accounting for death was utilized. Results: The 15-year cumulative incidence of any revision was 12%. There were 57 revisions, 27 of which involved revision of the fluted tapered component (FTC). Dislocation (n = 19), periprosthetic joint infection (n = 15), and aseptic loosening of the FTC (n = 11) were the most common reasons for revision. The 15-year cumulative incidence of any reoperation was 16%. The 15-year cumulative incidences were 6% for any FTC revision and 2% for FTC revision for aseptic loosening. Stem subsidence of >5 mm occurred in 2% of unrevised cases, and all but 1 stem was stable at the most recent follow-up. Conclusions: This large series of MFT stems used in aseptic revision THAs had a 2% incidence of subsequent revision of the FTC for aseptic loosening at 15 years. Dislocation and infection were the most common reasons for any revision. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Background: Porous metaphyseal cones are frequently utilized during revision total knee arthroplasty (TKA) procedures. The purpose of the present study was to evaluate 3D-printed metaphyseal cones used for revision TKA, with specific emphasis on implant survivorship, radiographic appearance, and clinical outcomes after short-term follow-up. Methods: We identified 740 cones (498 tibial, 242 femoral) that had been inserted during 533 revision TKA procedures that had been performed at a single tertiary care academic institution. Aseptic loosening (n = 199), periprosthetic joint infection (PJI) (n = 183), and instability (n = 84) were the most common reasons for the index revision. Type-2B or 3 bone loss was present in 67% of the knees. The mean age was 66 years, the mean body mass index was 34 kg/m 2 , and 55% of the patients were female. Serial radiographs were reviewed. The mean duration of follow-up was 4 years. Results: The 5-year cumulative incidence of cone revision for aseptic loosening was 1% (95% confidence interval [CI], 0% to 3%). The 5-year cumulative incidence of any cone revision or removal was 6% (95% CI, 4% to 9%). In total, 37 cones (19 femoral, 18 tibial) were revised, with PJI (n = 23; 14 recurrent), periprosthetic femoral fracture (n = 3), arthrofibrosis (n = 3), and aseptic loosening of the femoral component and femoral cone (n = 3) as the most common reasons for cone revision. The 5-year cumulative incidence of any TKA re-revision was 14% (95% CI, 11% to 18%). There were a total of 67 re-revisions, with PJI (n = 38), persistent drainage (n = 6), and extensor mechanism disruption (n = 3) being the most common reasons. Radiographically, 2 unrevised femoral cones and 1 unrevised tibial cone appeared to be possibly loose; all 3 cones were in knees with distal femoral replacements or hinged constructs. Conclusions: This large series showed that 3D-printed titanium metaphyseal cones were very durable at short-term follow-up, with a 5-year cumulative incidence of cone revision for aseptic loosening of 1%. PJI was the most common reason for cone revision and any revision. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

AbstractTo minimize periprosthetic joint infection (PJI) risk, some clinicians prescribe extended antibiotic prophylaxis (EAP) following total joint arthroplasty (TJA). Given the limited evidence supporting EAP, we sought to evaluate impact of prophylactic antibiotic duration on PJI risk in a murine TJA model. A titanium prosthesis was implanted into the proximal tibia of 89 mice and inoculated with 102 colony forming units (cfu) of Staphylococcus aureus Xen36. Control mice (n = 20) did not receive antibiotics. Treated mice received either 24 h (n = 35) or 4 days (n = 34) of cefazolin prophylaxis. Cultures were obtained from the prostheses, tibia, femur, and knee tissues 3 weeks after surgery. All mice in the control group developed PJI. Both prophylaxis regimens reduced the rate of PJI relative to the control, with only 2/35 mice in the 24‐h cohort (p < 0.0001) and 1/34 in 4‐day cohort developing PJI (p < 0.0001). CFU counts from the prostheses, bone and knee tissues were reduced for the 24‐h and 4‐day prophylaxis cohorts relative to the control (p < 0.0001 for both). There was no difference in rates of PJI or CFU counts between the two prophylaxis cohorts (p = 0.58). Prophylactic cefazolin profoundly reduced rates of PJI in a murine model of TJA in which all control animals developed PJI. Extending cefazolin prophylaxis duration from 24 h to 4 days did not result in improved PJI rates or decreased bacterial loads in infected cases. While these results strongly support use of antibiotic prophylaxis for TJA, EAP did not appear to add benefit in the described mouse model.

Background: Metaphyseal cones with cemented stems can be successfully utilized in most revision total knee arthroplasties (TKAs). However, if the diaphysis has been previously violated, fixation of the cemented stem, which is important for cone ingrowth and construct survival, can be compromised. The initial results of our novel technique combining diaphyseal impaction bone-grafting with a metaphyseal cone were promising but required additional study. The purpose of the present study was to assess results of this technique in a larger cohort. Methods: A metaphyseal cone combined with diaphyseal impaction grafting and a cemented stem was utilized in 88 revision TKAs at our institution, including 35 from our prior study. The mean age at the time of revision was 67 years, and 67% of patients were male. Patients had had a mean of 4 prior knee arthroplasty procedures. The 2 most common reasons for revision were aseptic loosening (78%) and 2-stage reimplantation for periprosthetic joint infection (PJI) (19%). The mean follow-up was 4 years. Results: At the time of the latest follow-up, no cone-impaction grafting constructs required re-revision for aseptic loosening. Five-year survivorship free from any revision of the cone-impaction grafting construct and free from any reoperation was 95% and 65%, respectively. A total of 25 knees (28%) underwent reoperation, with the 2 most common indications being PJI and periprosthetic fracture. All cones were osseointegrated, and all bone graft appeared stable or incorporated. One patient had radiographic evidence of tibial component loosening despite a well-fixed cone; however, this patient was asymptomatic and had not undergone revision at 9 years. Conclusions: When presented with a sclerotic, polished diaphyseal canal with deficient cancellous bone and concomitant metaphyseal bone loss, our technique of combining diaphyseal impaction grafting with a metaphyseal cone proved extremely durable in this larger series of patients. No cone-impaction grafting constructs required re-revision for aseptic loosening. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Background: There has been a paucity of long-term outcomes data on aseptic revision total hip arthroplasties (THAs) in the young adult population. The purpose of this study was to evaluate implant survivorship, complications, and clinical outcomes in a large cohort of contemporary aseptic revision THAs in patients ≤50 years of age at the time of the surgical procedure. Methods: We identified 545 aseptic revision THAs performed at a single academic institution from 2000 to 2020 in patients who were 18 to 50 years of age. Patients who underwent conversion THAs and patients with a history of any ipsilateral hip infection were excluded. The mean age was 43 years, the mean body mass index (BMI) was 29 kg/m 2 , and 63% were female. The index indication for revision THA was aseptic loosening in 46% of cases, polyethylene wear or osteolysis in 28% of cases (all revisions of conventional polyethylene), and dislocation in 11% of cases. There were 126 hips (23%) that had undergone at least 1 previous revision (median, 1 revision [range, 1 to 5 revisions]). The mean follow-up was 10 years. Results: In the entire cohort, the 20-year survivorship free of any re-revision was 76% (95% confidence interval [95% CI], 69% to 82%). There were 87 re-revisions, with 31 dislocations, 18 cases of aseptic loosening of the femoral component, and 16 periprosthetic joint infections (PJIs) being the most common reasons for re-revision. Dislocation as the indication for the index revision was associated with an increased risk of re-revision (hazard ratio, 2.9; p < 0.001). The 20-year survivorship free of any reoperation was 73% (95% CI, 66% to 78%). There were 75 nonoperative complications (14%), including 32 dislocations. The mean Harris hip score significantly improved (p < 0.001) from 65 preoperatively to 81 at 10 years postoperatively. Conclusions: Contemporary aseptic revision THAs in patients ≤50 years of age demonstrated a re-revision risk of approximately 1 in 4 at 20 years. Dislocation, aseptic loosening of the femoral component, and PJI were the most common reasons for re-revision. Index revision THAs for dislocation had a 3 times higher risk of re-revision. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Abstract Background The first-line management strategy for acute periprosthetic joint infections (PJIs) is debridement, antibiotics, and implant retention (DAIR). Suppressive antibiotic therapy (SAT) after DAIR is proposed to improve outcomes, yet its efficacy remains under scrutiny. Methods We conducted a multicenter retrospective study in patients with acute PJI of the hip or knee who were treated with DAIR in centers from Europe and the United States. We analyzed the effect of SAT using a Cox model landmarked at 12 weeks. The primary covariate of interest was SAT, which was analyzed as a time-varying covariate. Patients who experienced treatment failure or were lost to follow-up within 12 weeks were excluded from the analysis. Results The study included 510 patients with 66 treatment failures with a median follow-up of 801 days. We did not find a statistically significant association between SAT and treatment failure (hazard ratio, 1.37; 95% CI, .79–2.39; P = .27). Subgroup analyses for joint, country cohort, and type of infection (early or late acute) did not show benefit for SAT. Secondary analysis of country cohorts showed a trend toward benefit for the US cohort (hazard ratio, 0.36; 95% CI, .11–1.15; P = .09), which also had the highest risk of treatment failure. Conclusions The utility of routine SAT as a strategy for enhancing DAIR's success in acute PJI remains uncertain. Our results suggest that SAT's benefits might be restricted to specific groups of patients, underscoring the need for randomized controlled trials. Identifying patients most likely to benefit from SAT should be a priority in future studies.

AbstractAdipoRon is an adiponectin receptor 1, 2 (ADIPOR1 and ADIPOR2) agonist with potential antifibrotic effects. Whether AdipoRon can mitigate joint stiffness in a rabbit model of arthrofibrosis is unknown. We examined the efficacy of intravenous (IV) AdipoRon at mitigating contracture in a rabbit model of knee arthrofibrosis. Fifty‐six female New Zealand White rabbits were divided into three dosing groups: vehicle (dimethyl sulfoxide, DMSO), 2.5 mg/kg AdipoRon, and 5 mg/kg AdipoRon. AdipoRon, in DMSO, was administered IV preoperatively and for 5 days postoperatively (30 rabbits, Aim 1). AdipoRon was again dosed similarly after Kirschner wire (K‐wire) removal at 8 weeks (26 rabbits; Aim 2). The primary outcome of joint passive extension angle (PEA,°) was measured at 8, 10, 12, 16, and 24 weeks following index surgery. At 24 weeks, rabbits were euthanized and limbs were harvested to measure posterior capsular stiffness (N cm/°). In Aim 1, the 5 mg/kg treated rabbits had a significant increase in PEA when compared to controls at 16‐week (p < 0.05). In Aim 2, the 5 mg/kg treated rabbits had a significant increase in PEA when compared to controls at 10‐week (p < 0.05). In both aims, no significant differences were observed at later time points. Capsular stiffness was no different in any group. We are the first to report the efficacy of IV AdipoRon in a rabbit model of arthrofibrosis. We identified a significant dose‐dependent decrease in joint PEA at early time points; however, no differences were observed between groups at later time points. Clinical Significance: The present investigation provided the first assessment of AdipoRon's efficacy in mitigating knee stiffness in the current gold standard rabbit model of arthrofibrosis. Results of this investigation provided further evidence as to the potential role of AdipoRon as a preventative for arthrofibrosis in large mammals.

Marlex mesh reconstruction of the extensor mechanism following total knee arthroplasty (TKA) has demonstrated excellent early results. The purpose of the present study was to evaluate longer-term results of Marlex mesh reconstruction of the extensor mechanism in 93 TKAs. Seventy-seven reconstructions were aseptic, and 16 were performed as part of a 2-stage exchange for the treatment of infection. Mean follow-up was 8 years. Twenty-eighty patients experienced mesh failure. Seventeen failures were treated with mesh revision (8 for patellar tendon rupture, 7 for quadriceps tendon rupture, and 2 for symptomatic lengthening). The 10-year cumulative incidence of mesh revision for mesh failure was 20%. Extensor lag improved by a mean of 28°, with a mean extensor lag of 9° at most recent follow-up. At a mean follow-up of 8 years, Marlex mesh reconstruction was a durable and reliable technique to treat both aseptic and septic ruptures of the extensor mechanism. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

AbstractArthrofibrosis, which causes joint motion restrictions, is a common complication following total knee arthroplasty (TKA). Key features associated with arthrofibrosis include myofibroblast activation, knee stiffness, and excessive scar tissue formation. We previously demonstrated that adiponectin levels are suppressed within the knee tissues of patients affected by arthrofibrosis and showed that AdipoRon, an adiponectin receptor agonist, exhibited anti‐fibrotic properties in human mesenchymal stem cells. In this study, the therapeutic potential of AdipoRon was evaluated on TGFβ1‐mediated myofibroblast differentiation of primary human knee fibroblasts and in a mouse model of knee stiffness. Picrosirius red staining revealed that AdipoRon reduced TGFβ1‐induced collagen deposition in primary knee fibroblasts derived from patients undergoing primary TKA and revision TKA for arthrofibrosis. AdipoRon also reduced mRNA and protein levels of ACTA2, a key myofibroblast marker. RNA‐seq analysis corroborated the anti‐myofibrogenic effects of AdipoRon. In our knee stiffness mouse model, 6 weeks of knee immobilization, to induce a knee contracture, in conjunction with daily vehicle (DMSO) or AdipoRon (1, 5, and 25 mg/kg) via intraperitoneal injections were well tolerated based on animal behavior and weight measurements. Biomechanical testing demonstrated that passive extension angles (PEAs) of experimental knees were similar between vehicle and AdipoRon treatment groups in mice evaluated immediately following immobilization. Interestingly, relative to vehicle‐treated mice, 5 mg/kg AdipoRon therapy improved the PEA of the experimental knees in mice that underwent 4 weeks of knee remobilization following the immobilization and therapy. Together, these studies revealed that AdipoRon may be an effective therapeutic modality for arthrofibrosis.

Background: As the number of primary total hip arthroplasty procedures performed each year continues to rise, so too do the number of complications, including periprosthetic femoral fracture 1–9 . Vancouver B2 and B3 periprosthetic femoral fractures are difficult to treat because they require the surgeon to simultaneously manage a femoral fracture and gain new implant fixation. Fluted tapered stems have advanced the treatment of periprosthetic femoral fractures by providing immediate axial and rotational implant fixation distal to the fracture 10–18 . Modular fluted tapered stems provide the added practical advantage of allowing length and anteversion adjustment after implantation of the distal fixation portion of the stem. Description: In this technique, a modified extended trochanteric osteotomy incorporating the fracture is utilized to gain access to the loose femoral implant and femoral diaphyseal canal. The femoral diaphyseal canal is then sequentially reamed in 1-mm increments. A fluted tapered stem with the appropriate length, diameter, and axial and rotational stability is inserted into the canal. A proximal body is then chosen that establishes the appropriate leg length, femoral offset, and version. The final proximal body is engaged into the fluted tapered stem. Finally, the fracture is fixed around the implant with a combination of cables or wires. Alternatives: Historically, implants such as extensively porous coated stems were utilized to treat Vancouver B2 or B 3 periprosthetic femoral fractures. Unfortunately, these implants were associated with high rates of failure and revision 7,9 . Rationale: The introduction of a fluted tapered stem provided a more reliable implant that achieves immediate axial and rotational stability. In addition, utilizing a fluted tapered stem allowed for a more soft-tissue-preserving approach to these complex injuries, in turn allowing the fracture to be reduced around the implant proximally with cerclage cables and or wires. Modular fluted tapered stems provide the additional advantage of allowing the surgeon to modify leg length, offset, and femoral version, independently of the fluted tapered stem. As a result of these unique advantages, these stems were introduced several years ago for the treatment of Vancouver B 2 or B 3 periprosthetic femoral fractures. Expected Outcomes: Contemporary series have demonstrated that the use of a modular fluted tapered stem leads to improved implant survivorship and clinical outcomes with lower complication rates for Vancouver B2 and B 3 periprosthetic femoral fractures 1,10–12,14–19 . Important Tips: Template both the fluted tapered stem and proximal body preoperatively. The proximal body should be templated at the ideal hip center of rotation that appropriately restores leg lengths and offset. Template the fluted tapered stem so that it provides appropriate isthmic fit and bypasses the most distal extent of the fracture by at least 2 cortical diameters. Utilize a modified extended trochanteric osteotomy for your exposure in order to facilitate visualization of the fracture and to provide direct access to the femoral canal. Place a prophylactic cable prior to preparing the femur for the implant in order to help prevent iatrogenic fracture. Place a trial stem and obtain intraoperative anteroposterior and lateral radiographs in order to assess the position of the implants and the risk of anterior cortical perforation. When placing the final implants, be sure the fluted tapered stem has both axial and rotational stability. Reduce and fix the fracture after the final implants are placed and the hip is reduced. Acronyms and Abbreviations: AP = anteroposterior MFT = modular fluted tapered (stem) ETO = extended trochanteric osteotomy THA = total hip arthroplasty CT = computed tomography PJI = periprosthetic joint infection