Abdel, Matthew P.

Aims Arthrofibrosis affects a notable percentage of patients after total knee arthroplasty (TKA). Elevated serum mast cell tryptase (SMCT) levels have been linked to fibrosis, suggesting that SMCT could serve as a biomarker for arthrofibrosis. As such, the aims of this study were to assess SMCT levels in TKA patients, and their possible association with arthrofibrosis and clinical outcomes in a prospective clinical trial. Methods We conducted a prospective study involving 219 patients undergoing primary TKA at a single academic medical centre between January 2018 and December 2022. SMCT levels were measured preoperatively, immediately postoperatively, and at six weeks, three months, and one year postoperatively. Secondary outcomes included revision rates, complications, and Knee Society Scores (KSSs). Allergic and inflammatory conditions were assessed for their influence on SMCT levels. Results At one year postoperatively, eight patients had developed arthrofibrosis (4%), and three (1.5%) had undergone manipulation under anaesthesia. The mean preoperative SMCT level was 5.6 µg/L (SD 3.4), which decreased significantly to 4.1 µg/L (SD 2.7) immediately postoperatively (p < 0.001). At six weeks the mean SMCT level was 6.4 µg/l (SD 4.1), and was 6.1 µg/l at both three months (SD 4.1) and one year (SD 4.0). Elevated preoperative SMCT levels were not significantly associated with the risk of arthrofibrosis development (OR 3; p = 0.370), nor were immediate postoperative levels (OR 2; p = 0.754) or those at six weeks (OR 1; p = 0.989). Of note, elevated SMCT levels at three months (OR 5; 95% CI 0.4 to 64; p = 0.191) and one year (OR 13; 95% CI 1 to 232; p = 0.077) trended toward an increased risk of arthrofibrosis development, without reaching significance. Conclusion In patients undergoing TKA, with the numbers included in this study, there was no significant difference in SMCT levels between patients who did and did not develop arthrofibrosis at any timepoint. However, there was a trend towards elevated SMCT levels at three months and one year in those who developed arthrofibrosis, which merits further study. Cite this article: Bone Joint Res 2025;14(11):1045–1052.

Arthrofibrosis is a common complication following total knee arthroplasty and is the result of a dysregulated immuno-inflammatory cascade, which culminates in excessive scar deposition by myofibroblasts within the knee joint. Pharmacotherapies for arthrofibrosis are limited, with treatment reliant on manipulation under anesthesia or lysis of adhesions with or without component revision. Bupivacaine (a local anesthetic) and meloxicam (a nonsteroidal anti-inflammatory drug) combination therapy may exert antifibrotic properties by limiting inflammatory cell recruitment and the subsequent release of profibrotic cytokines. The purpose of this study was to evaluate the effects of this combination therapy in a rabbit model of arthrofibrosis by evaluating live and postsacrifice knee biomechanics and gene expression of posterior knee capsule tissue. Forty New Zealand white rabbits were equally divided into two experimental groups and prospectively studied to assess knee passive extension angles (PEA), terminal posterior capsular stiffness, and the inflammatory milieu of the posterior knee joint capsule. Experimental limbs with and without combination therapy showed similar live PEAs and terminal posterior capsular stiffness, with no significant differences between the groups. Gene expression analysis, however, revealed significant reduction in inflammatory genes but not profibrotic genes. In summary, bupivacaine and meloxicam combination therapy did not exert antifibrotic effects in a rabbit model of arthrofibrosis but significantly reduced the expression of inflammatory markers in the local environment of the posterior capsule.

Background: An extended trochanteric osteotomy (ETO) is commonly used to improve exposure and facilitate femoral component removal in revision total hip arthroplasty (THA). An additional medial corticotomy may be used in conjunction with an ETO to correct a femoral deformity, particularly varus remodeling in association with a failed femoral component. This study evaluated the outcomes of combining an ETO with a medial corticotomy in revision THA, with emphasis on implant fixation, femoral alignment, bone union, and clinical outcomes. Methods: Of the 612 ETOs performed between 2003 and 2013, 13 patients (9 men and 4 women) underwent ETO combined with a medial corticotomy to correct varus remodeling, representing 2% of all ETOs during that period. The average follow-up was 8 ± 3.5 years. The mean age at surgery was 67 ± 13.5 years. The mean body mass index was 32 ± 7.7 kg/m 2 . Radiographs were reviewed to measure preoperative and postoperative femoral deformity, time to consolidation, and femoral fixation. Clinical outcomes were evaluated using the Harris Hip Score (HHS). Results: All patients had preoperative varus femoral deformity (mean 16.3° ± 5.7°). The mean postoperative alignment was 4.3 ± 1.6° varus achieving an average correction of 12° (95% CI −15.7 to −8.3, p < 0.0001). Both the ETO and the medial corticotomy consolidated in 10 of 11 patients (91%) with available 1-year radiographs at a mean of 11 ± 7.7 months. The mean HHS improved significantly from 42 preoperatively to 82 at 5-year follow-up (p = 0.0002). Complications related to the ETO and corticotomy occurred in 4 patients (30%), including 1 intraoperative fracture, 1 postoperative greater trochanteric fracture, 1 nonunion of the medial corticotomy, and 1 postoperative wound-hematoma. All femoral components remained well fixed at final follow-up. Conclusion: The combination of ETO and medial corticotomy in revision THA effectively corrected femoral alignment in patients with a preoperative varus deformity and was associated with significant functional improvement at the final follow-up. Level of Evidence: Level IV . See Instructions for Authors for a complete description of levels of evidence.

Background: Although patients often aim to lose weight after total hip arthroplasty (THA) or total knee arthroplasty (TKA), long-term changes in body mass index (BMI) are unknown. We analyzed BMI at 2, 5, and 10 years after primary THA and TKA and determined predictors of BMI change. Methods: We identified patients who underwent primary THA or TKA for osteoarthritis between 2001 and 2011 and had a BMI at surgery and at 2, 5, and 10 years postoperatively. This resulted in 763 patients (310 who underwent THA and 453 who underwent TKA). The mean patient age was 66 years, and 60% of patients were female. BMI changes were analyzed with repeated-measures analysis of variance. Multinomial logistic regression determined predictors of BMI change. Results: Following THA, the mean BMI increased from 30.3 kg/m 2 at surgery to 30.9 kg/m 2 at both 2 years (p = 0.003) and 5 years (p = 0.002). Following TKA, the mean BMI increased from 32.7 kg/m 2 at surgery to 33.1 kg/m 2 at both 2 years (p = 0.053) and 5 years (p = 0.040). By 10 years, the mean BMI was 30.6 kg/m 2 (p = 0.453) for patients undergoing THA and 32.6 kg/m 2 (p = 0.947) for patients undergoing TKA, similar to the BMIs at surgery. At 10 years, 27% of patients who underwent THA and 30% of patients who underwent TKA had a BMI decrease of >5%, whereas 30% of patients who underwent THA and 32% of patients who underwent TKA had a BMI increase of >5%. Female sex among patients who underwent THA increased the odds of a >5% BMI increase at 10 years (odds ratio [OR], 2.1; p = 0.006). Older age among patients who underwent TKA decreased the odds of a >5% BMI increase at 10 years (OR per year, 0.95; p < 0.001). Conclusions: Although most patients experienced a BMI change of >5% at 10 years, the mean BMI did not meaningfully change 2, 5, or 10 years after THA or TKA. Arthroplasty should not be viewed as a gateway to BMI improvement for patients overall, but female sex and older age may predict clinically important weight changes 10 years after arthroplasty. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Background: Surgeons often recommend weight loss for patients with obesity before total knee arthroplasty (TKA). However, it is unknown whether preoperative weight loss affects outcomes. The goals of this study were to determine how many patients with obesity lost weight before TKA, to identify weight loss predictors, and to evaluate if preoperative weight loss affected postoperative outcomes. Methods: Among 23,726 primary TKAs performed between 2002 and 2019, we identified 3,665 patients who had a body mass index (BMI) of ≥30 kg/m 2 measured 1 to 24 months before surgery and had a weight measured at surgery. The mean patient age was 68 years, and 59% of patients were female. The mean patient BMI was 36 kg/m 2 . Univariable linear regressions evaluated weight loss predictors. Univariable and multivariable logistic regressions and Cox proportional hazards models evaluated the impact of preoperative weight change on discharge, operative time, periprosthetic joint infections (PJIs), complications, revisions, and reoperations. The mean follow-up was 6 years. Results: Overall, 20% of patients gained ≥5 pounds (1 pound = 0.45 kg), 39% maintained weight, 17% lost 5 to <10 pounds, 15% lost 10 to <20 pounds, and 9% lost ≥20 pounds before TKA. Male patients lost slightly more weight (−4.6 pounds) than female patients (−4.3 pounds) (p = 0.05). In univariable analyses, gaining >5 pounds was associated with increased odds of extended hospital length of stay (odds ratio [OR], 1.4; p = 0.01) and risk of complications (hazard ratio [HR], 1.7; p < 0.01). Losing 10 to <20 pounds was associated with increased risks of revision (HR, 2.0; p = 0.01), PJI (HR, 3.1; p < 0.01), and complications (HR, 1.6; p = 0.03). In multivariable analyses, compared with maintaining weight, losing 10 to <20 pounds was associated with an increased risk of PJI (HR, 2.6; p = 0.01), whereas gaining >5 pounds was associated with an increased risk of complications (HR, 1.5; p = 0.03). Conclusions: Few patients with obesity lost substantial weight before primary TKA, and reaching common preoperative weight loss goals was not associated with improved outcomes. Although a healthy weight is important for general health, weight loss before TKA may not be sufficient to improve postoperative outcomes for most patients with obesity. Level of Evidence: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Background: The U.S. Food and Drug Administration has approved a bupivacaine and meloxicam extended-release (ER) intra-articular injection for pain during total knee arthroplasty (TKA). However, the real-world evidence with regard to analgesic efficacy of that medication has been limited. This randomized clinical trial investigated the efficacy of this new medication compared with our standard periarticular injection for postoperative analgesia after primary TKA. Methods: Eligible patients undergoing primary, unilateral TKA for osteoarthritis at our academic center were enrolled. Patients were blinded and were randomized 1:1 to the bupivacaine-meloxicam ER (ZYNRELEF) injection group or the standard injection (ropivacaine, ketorolac, epinephrine) control group. A standardized, multimodal analgesic pathway was implemented. Numeric Rating Scale (NRS) pain scores and tallies of opioid consumption were collected. The primary outcome was the area under the curve (AUC) for NRS pain, adjusted for opioid consumption, over 72 hours. The minimal clinically important difference was considered to be 30%. Power analysis determined a minimum of 44 patients per group. The final groups included 53 patients in the experimental group and 48 patients in the control group. Results: Similar postoperative analgesia was observed, with an AUC for the adjusted NRS pain score up to 72 hours of 331 in the experimental group and 373 in the control group (p = 0.09). The mean maximum NRS pain scores were similar and reflected good, but not complete, analgesia. Scores were 3 to 5 on the day of the surgery, 4 to 6 on postoperative day (POD) 1, 5 to 6 on POD 2, and 4 to 5 on POD 3 (p > 0.05). One patient in the experimental group and 2 patients in the control group had early postoperative complications, none of which was deemed to be related to the analgesic choice. Conclusions: This randomized clinical trial demonstrated similar analgesia with a bupivacaine-meloxicam ER solution and a standard periarticular injection up to 72 hours after primary TKA. Cost, reimbursement, and convenience may ultimately prove to be more important than analgesic differences when choosing between these 2 effective options for managing postoperative pain. Level of Evidence: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Aims The use of jumbo femoral heads, defined as those with a diameter of ≥ 40 mm, in primary total hip arthroplasty (THA) has gained popularity, to mitigate dislocation. The aim of this study was to determine the risk of dislocation, implant survival, and clinical outcomes of a large cohort of primary THAs with jumbo femoral heads. Methods We conducted a retrospective analysis of 1,828 primary THAs with jumbo femoral heads, which were undertaken for osteoarthritis, in 1,578 patients between January 2000 and December 2022, at a single academic medical centre. The femoral head diameter was 40 mm in 1,584 THAs (87%) and 44 mm in 244 THAs (13%). The outer diameter of the acetabular component ranged from 52 mm to 72 mm in those with 40 mm heads, and from 54 mm to 78 mm in those with 44 mm heads. The types of bearing included ceramic-on-highly cross-linked polyethylene (1,229 THAs; 67%) and metal-on-polyethylene (599 THAs; 33%). Elevated liners were used in 472 THAs (26%) and 1,083 (59%) were lateralized. The most common operative approach was posterior (1,388 THAs; 76%). Outcomes of interest included the rate of dislocation, revision for dislocation, any revision, any reoperation, and the Harris Hip Score (HHS). The mean age of the patients at the time of THA was 64 years (8 to 94); 1,477 (81%) were male, and their mean BMI was 28 kg/m² (5 to 55). The mean follow-up was six years (2 to 14). Results The ten-year survival free of dislocation was 97% (95% CI 96 to 98; 97% for 40 mm heads (95% CI 95 to 98) and 99% for 44 mm heads (95% CI 97 to 100) (hazard ratio 3 (95% CI 1 to 14); p = 0.106)). The ten-year survival free of revision for dislocation was 99.6% (95% CI 99 to 100) (99.5% for 40 mm heads (95% CI 98 to 100) and 100% for 44 mm heads (p = 0.546)). The ten-year survival free of any revision and any reoperation was 95% (95% CI 94 to 97) and 93% (95% CI 91 to 95), respectively. There were no significant differences in survival free of any revision (p = 0.746) or any reoperation (p = 0.762) between the two groups. Conclusion In this large single-centre study of the use of jumbo femoral heads in primary THAs, the ten-year survival free of dislocation was 97%, with extremely few revisions for dislocation. These results highlight the potential for jumbo femoral heads to reduce the risk of dislocation and enhance implant longevity without compromising other clinical outcomes. Cite this article: Bone Joint J 2025;107-B(7):698–706.

AimsTo characterize the effects of varying experimental parameters of transforming growth factor-beta 1 (TGF-β1) in primary knee fibroblasts as an in vitro model of arthrofibrosis.MethodsPrimary knee fibroblasts were isolated from one patient undergoing primary total knee arthroplasty (TKA) and one patient undergoing revision TKA for arthrofibrosis, respectively. Fibroblasts were stimulated with varying concentrations and durations of the pro-fibrotic cytokine TGF-β1. Picrosirius red staining (PSR) was conducted to assess collagen deposition, and real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting were performed to determine cellular gene expression levels. A collagen gel contraction assay was used to assess TGF-β1-induced fibroblast contraction.ResultsIn our experiments, TGF-β1-mediated collagen deposition was consistent across a vast concentration range (0.5 to 40 ng/ml). While α-smooth muscle actin (ACTA2) protein levels and SMAD2 phosphorylation were induced by low concentrations (1 ng/ml), robust ACTA2 transcription required higher concentrations (5 ng/ml) of TGF-β1. Evaluation of TGF-β1-mediated cell and cytoskeletal contractility shows that in the measured fibroblasts, this process occurs within three hours following TGF-β1 administration. Of note, TGF-β1-differentiated myofibroblasts exhibited greater contractile properties than naïve fibroblasts in the presence of TGF-β1.ConclusionTaken together, this study elucidates key TGF-β1 experimental parameters that will inform the development and interpretation of in vitro models of arthrofibrosis.Cite this article: Bone Joint Res 2025;14(6):527–538.

Aims An angular proximal femoral deformity, in association with osteoarthritis (OA) of the hip, considerably increases the technical complexity of primary total hip arthroplasty (THA). The aims of this study were to determine the long-term implant survival, the risk factors for failure, complications, and clinical outcomes of contemporary primary THA in this difficult group of patients. Methods Our institutional total joint registry was used to identify 119 primary THAs performed in 108 patients with an angular proximal femoral deformity, between January 1997 and September 2017. The deformity was related to a previous femoral osteotomy in 102 THAs (86%), and developmental or metabolic disorders in 17 THAs (14%). A total of 62 hips (53%) had a predominantly varus deformity. The mean age of the patients was 44 years (SD 13), their mean BMI was 29 kg/m 2 (SD 6), and 70 (59%) were female. An uncemented femoral component with metaphyseal fixation was used in 35 THAs (30%), an uncemented femoral component with diaphyseal fixation in 34 (29%), an uncemented modular femoral component with a metaphyseal fixation sleeve in 29 (24%), and a cemented femoral component in 21 (18%). Simultaneous corrective femoral osteotomy was performed in 22 THAs (18%). Kaplan-Meier survival and Harris Hip Scores (HHSs) were reported. The mean follow-up was eight years (2 to 22). Results The ten-year survival free of femoral loosening, any femoral revision, any revision and any reoperation was 95%, 93%, 90%, and 88%, respectively. A total of 13 revisions were undertaken, for aseptic femoral loosening in three, fracture of the femoral component in two, dislocation in two, aseptic acetabular loosening in two, polyethylene liner exchange in two, and infection in two. A preoperative varus deformity was associated with a higher risk of any revision (hazard ratio (HR) 12.5, p = 0.020), and those with a simultaneous osteotomy had a higher risk of any reoperation (HR 3.6, p = 0.023). The mean HHSs improved significantly from 52 preoperatively to 82 at ten years (p < 0.001). Conclusion In the largest series to date of primary THAs in patients with hip OA and an angular proximal femoral deformity, we found a good ten-year survival free from any revision. Varus deformities, particularly those treated with a simultaneous osteotomy due to the magnitude or location of the deformity, had a higher rate of further surgery. Cite this article: Bone Joint J 2025;107-B(6 Supple B):101–108.

Background: Periprosthetic tibial fractures around a total knee replacement (TKR) remain challenging to manage, with little published information for guidance. The purpose of this study was to review the types, management techniques, and outcomes of periprosthetic tibial fractures in the largest series to date. Methods: We identified 300 periprosthetic tibial fractures (285 patients) around a TKR (43% in primary TKRs and 57% in revision TKRs) sustained between 1996 and 2020. Fractures were classified according to Felix et al. as Type I (tibial plateau), Type II (adjacent to stem), Type III (distal to stem), or Type IV (tibial tubercle), with subtypes A (well-fixed component), B (loose component), and C (intraoperative fracture). Of the fractures in this study, 53% were Type I, 24% were Type II, 16% were Type III, and 8% were Type IV. A total of 46% of fractures occurred intraoperatively, and 54% of fractures occurred postoperatively (61% subtype A, 39% subtype B). The mean patient age at fracture was 67 years, and 64% of patients were female. The mean follow-up was 6 years. Results: The intraoperative fracture incidence was 1.40% in revision TKRs and 0.10% in primary TKRs. Among intraoperative fractures, the 2-year survivorship free from tibial component revision was highest in Type I (100%) and lowest in Type IV (67%) (p < 0.001). For postoperative fractures, the 2-year survivorship free from any reoperation was 29% and the 2-year survivorship free from tibial component revision was 51%. Type-I postoperative fractures had the lowest 2-year survivorship free from tibial component revision (10%), whereas Type-III fractures had the highest survivorship (88%) (p < 0.001). Conclusions: Intraoperative periprosthetic fracture of the tibia was fourteenfold more likely in revision TKRs compared with primary TKRs. Among all intraoperative fractures, Type-I fractures were well-tolerated, with 100% survivorship free from tibial component revision at 2 years. Conversely, Type-I postoperative fractures had only 10% survivorship at 2 years. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.