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Background: The number of revision total hip arthroplasties (THAs) is projected to reach 572,000 cases annually by 2030 in the United States. This may be attributed to the successes of primary THAs combined with an aging population, patients desire to remain active, and expanded indications for younger patients. Given the evolving nature of revision THAs, an epidemiological analysis of (1) etiologies; (2) demographics, including age and region; and (3) lengths of stay (LOSs) may minimize the gap between appropriate understanding and effective intervention. Methods: From 2016 to 2022, a national, all-payer database was queried. Incidences and indications were analyzed for a total of 102,476 patients who had revision THA procedures. Patients were stratified according to etiology of failure, age, US census region, primary payor class, and mean LOS. Results: The most common etiologies for revision THA procedures were dislocation (16.7%) and infection (12.7%), followed by periprosthetic fracture (6.9%). The largest age group was 65-74 years (30.9%), followed by >75 years (28.6%), then 55-64 (26.5%). The South had the largest total procedure cohort (36.9%), followed by the Midwest (27.5%), then the Northeast (19.7%), and the West (15.9%). The mean LOS was 4.10 days (range, 1.0-20.0). Conclusions: Dislocation and infection remain leading indications for revision THA. These findings can properly guide surgeons toward appropriate management as well as toward active steps to minimizing these outcomes.

Failed primary total knee arthroplasties are becoming more common among a younger, more active patient demographic. Aseptic failures with proximal tibial bone loss, specifically severe posterior tibial collapse, are difficult problems not well described in the literature. There are limited options for reconstructing large defects of the proximal tibia that appropriately restore slope while providing adequate structural support. To our knowledge, this technique to address a large, uncontained posterior proximal tibial defect has not been described in the literature. The purpose of this case report was to detail the surgical technique of how the implementation of cone technology with cementation techniques produced excellent clinical results for a patient with this difficult problem.

Abstract Arthrofibrosis following total knee arthroplasty (TKA) is a debilitating condition typically diagnosed based on clinical findings. To gain insight into the histopathologic immune cell microenvironment of arthrofibrosis, we assessed the extent of tissue fibrosis and quantified immune cell populations in specific tissue regions of the posterior capsule. We investigated specimens from three prospectively-collected, matched cohorts, grouped as patients receiving a primary TKA for osteoarthritis, revision TKA for arthrofibrosis, and revision TKA for non-arthrofibrotic, non-infectious reasons. Specimens were evaluated using hematoxylin and eosin staining, picrosirius red staining, immunofluorescence, and immunohistochemistry with Aperio®-based digital image analysis. Increased collagen deposition and increased number of α-SMA/ACTA2 expressing myofibroblasts were present in the arthrofibrosis group compared to the two non-arthrofibrotic groups. CD163 + macrophages were the most abundant immune cell type in any capsular sample with specific enrichment in the synovial tissue. CD163 + macrophages were significantly decreased in the fibrotic tissue region of arthrofibrosis patients compared to the patients with primary TKA, and significantly increased in adipose tissue region of arthrofibrotic specimens compared to non-arthrofibrotic specimens. Synovial CD117 + mast cells were significantly decreased in arthrofibrotic adipose tissue. Together, these findings inform diagnostic and targeted therapeutic strategies by providing insight into the underlying pathogenetic mechanisms of arthrofibrosis.

Aims: Outcomes of current operative treatments for arthrofibrosis after total knee arthroplasty (TKA) are not consistently positive or predictable. Pharmacological in vivo studies have focused mostly on prevention of arthrofibrosis. This study used a rabbit model to evaluate intra-articular (IA) effects of celecoxib in treating contracted knees alone, or in combination with capsular release. Methods: A total of 24 rabbits underwent contracture-forming surgery with knee immobilization followed by remobilization surgery at eight weeks. At remobilization, one cohort underwent capsular release (n = 12), while the other cohort did not (n = 12). Both groups were divided into two subcohorts (n = 6 each) – one receiving IA injections of celecoxib, and the other receiving injections of vehicle solution (injections every day for two weeks after remobilization). Passive extension angle (PEA) was assessed in live rabbits at 10, 16, and 24 weeks, and disarticulated limbs were analyzed for capsular stiffness at 24 weeks. Results: IA celecoxib resulted in greater mean PEA at ten weeks (69.6° (SD 4.6) vs 45.2° (SD 9.6), p = 0.004), 16 weeks (109.8° (SD 24.2) vs 60.9° (SD10.9), p = 0.004), and 24 weeks (101.0° (SD 8.0) vs 66.3° (SD 5.8), p = 0.004). Capsular stiffness was significantly reduced with IA celecoxib (2.72 Newton per cm (N·cm)/° (SD 1.04), p = 0.008), capsular release (2.41 N·cm/° (SD 0.80), p = 0.008), and capsular release combined with IA celecoxib (3.56 N·cm/° (SD 0.99), p = 0.018) relative to IA vehicle (6.09 N·cm/° (SD 1.64)). Conclusion: IA injections of a celecoxib led to significant improvements in passive extension angles, with reduced capsular stiffness, when administered to rabbit knees with established experimental contracture. Celecoxib was superior to surgical release, and the combination of celecoxib and a surgical release did not provide any additional value. Cite this article: Bone Joint Res 2022;11(1):32–39.

Background: Periprosthetic joint infections (PJIs) are devastating complications. Excessive anticoagulation with warfarin is an independent risk factor for PJIs. The use of a dedicated anticoagulation clinic to improve warfarin management has not been proven. Methods: Between 2006 and 2014, we identified 92 patients who were placed on postoperative warfarin, and later developed PJI. These patients were compared to 313 patients who underwent total joint arthroplasty placed on warfarin without developing PJI. Patients were included if they had no history of a venous thromboembolic event, were warfarin naive, and enrolled in the anticoagulation clinic. A univariate analysis compared independent variables, and statistical analysis was performed using Student's t-test and Pearson chi-square test for continuous and categorical variables. Results: Thirty-six PJI patients and 297 control patients met the inclusion criteria. The venous thromboembolism rate was 2.1%. At discharge, 82% of all patients were subtherapeutic. Patients were within their target international normalized ratio (INR) range 26.7% of the time. The mean INR in the initial postoperative period for the PJI group was 1.46 and 1.29 in the control group (P < .001). In the acute postoperative period, 13.3% of the knee PJI group were therapeutic or supratherapeutic compared with 3.5% in the knee control group (P = .002). Conclusions: Despite utilization of a dedicated anticoagulation clinic, patients were only within their target INR range 27% of the time. Total knee arthroplasty patients who developed a PJI were more likely to be therapeutic or supratherapeutic in the initial postoperative period. Consequently, the risks associated with warfarin as a venous thromboembolism prophylaxis may outweigh the potential benefits. Keywords: Total joint arthroplasty (TJA), Periprosthetic joint infection (PJI), International normalized ratio (INR), Warfarin, Venous thromboembolism (VTE), Pulmonary emboli (PE)