Citations

Abstract ICLA14 - The Extra-Articular Masterclass: Endoscopic Repairs, Ischiofemoral Fixes, and Complex Alignment, Auditorium A (BMCC Level 1), October 9, 2026, 14:00 - 16:00 Introduction Iliopsoas impingement (IPI) is an increasingly recognized cause of persistent groin pain and dysfunction after total hip arthroplasty (THA). The incidence of clinically important IPI requiring surgical treatment remains incompletely defined. For IPI refractory to conservative management surgical treatment options include acetabular revision, open tenotomy, or arthroscopic iliopsoas fractional lengthening and often is done years following initial symptom onset. As such, the true incidence of persistent IPI and associated risk factors resulting in subsequent surgical management are incompletely characterized. We sought to determine the prevalence of, and risk factors for, surgical IPI treatment after primary THA at a single high-volume institution. Materials and Methods We performed a retrospective review of all primary THAs done from 2010 to 2025 and identified subsequent surgical IPI procedures performed within our health system during the same period. Patient demographics, surgical approach, and implant specific criteria were evaluated. Univariable and multivariable Cox proportional hazards models were used to determine risk factors associated with surgical IPI treatment. Results Seventy-one Iliopsoas Impingement Management (IPIM) procedures were performed after 18,497 primary THAs (prevalence, 0.4%). The prevalence by surgical approach was 0.4% for direct anterior, 0.5% for lateral, and 0.3% for posterior approaches. In multivariable analysis, factors associated with surgical IPI treatment included female sex (hazard ratio [HR], 2.35; p=0.001), direct anterior approach compared with posterior approach (HR, 2.06; p=0.024), and younger age (HR, 0.97; p<0.001). Body mass index, acetabular component size, anteversion, and inclination were not associated with IPIM (p≥0.074 ). Conclusion Surgical treatment of IPI after primary THA was uncommon (0.4%) but not rare. Women, younger patients, and those treated with a direct anterior approach had a greater risk of subsequent surgical IPI treatment. These findings may assist in patient counseling and in setting expectations regarding the likelihood of iliopsoas-related reoperation after contemporary primary THA.

Abstract ICLA12 - The Chondral Masterclass: Advanced Scaffolds, Orthobiologic Realities, and Young THA, Auditorium B (BMCC Level 1), October 9, 2026, 10:30 - 12:30 Introduction Total hip arthroplasty (THA) in patients with open triradiate cartilage is rare, but results in good midterm survivorship and clinical outcomes in failed hip preservation adolescents. Currently, there is limited literature evaluating the potential impact of THA on further acetabular and pelvic growth, and common radiographic parameters in the setting of an open triradiate cartilage. Our primary aim was to assess the acetabular component position at midterm follow up after THA in skeletally immature patients with open triradiate cartilage. Our secondary aim was to report midterm radiographic and clinical outcomes, including leg length and offset, after THA in patients with open triradiate cartilage. Methods Our institutional Total Joint Registry was queried to identify 24 THAs (23 patients) with an open triradiate cartilage at the time of index operation between 2000 and 2024. Skeletal maturity was assessed utilizing the modified Oxford bone age, with only triradiate scores of 1 and 2 included. Demographic, implant, and radiographic data were collected. Acetabular component inclination and version, leg lengths, and femoral and acetabular offset were measured on anteroposterior and cross table lateral radiographs immediately postoperatively and at final follow-up. The final cohort for radiographic analysis included 20 THAs (17 patients) with a mean age of 14 years and 55% male. Patients had a mean BMI of 26 kg/m2 and mean modified Oxford bone age score of 21.6. Mean follow up with radiographs was 5.7 years (median=4.9, SD=3.8). Results The indications for THA were avascular necrosis (70%), secondary arthritis (25%), and neoplasia (5%). Acetabular component inclination (Mean change in inclination 0.91°, 95% CI inclination [-4.4, 2.7], p=0.61) and acetabular component version (Mean change in anteversion -2.8°, 95% CI [-3.3, 8.9], p=0.35) did not change from immediately postoperatively to final follow-up. Similarly, there was no change in leg length (Mean change in leg length -0.5mm, 95% CI [-2.0, 5.0], p=0.38) at final follow-up. There was one revision for acetabular component loosening and no separate reoperations. The survivorships free of revision and reoperation were 95%, respectively. Conclusion Acetabular component version and inclination remain unchanged following THA performed in skeletally immature patients with open triradiate cartilage. Survivorship free of revision was excellent at 95% in mid-term follow up of 6 years. These findings suggest that THA is safe and durable in skeletally immature patients with minimal risk of implant positional change or significant leg length discrepancy during final skeletal maturation.

Abstract ICLB09 - The Revision Playbook: Advanced Execution and Technical Rescues in Failed Preservation, Session Room 6 (BMCC Level 3), October 9, 2026, 10:30 - 12:30 Purpose To evaluate outcomes of revision hip arthroscopy by prior surgical procedure, revision indication, and to compare patient-reported outcomes and rates of re-revision or conversion to arthroplasty across revision indications and procedures performed. Methods A retrospective review was conducted of patients undergoing first-time revision hip arthroscopy between 2011 and 2020 at a single institution. Operative details were collected at both the index and revision surgeries, including whether cam or pincer resection was performed. Patient reported outcome measures (PROMs) were collected for patients without revision failure. Rates of re-revision arthroscopy or conversion to total hip arthroplasty (THA) were measured. Statistical analysis included appropriate tests for group comparisons and Cox proportional hazards models to identify predictors of failure. Results A total of 68 hips were included (mean age 33 ± 11.7 years, 81.2% female). The most common indications for revision were recurrent labral tear (89.9%) and residual femoroacetabular impingement (FAI) (63.8%). At index arthroscopy, 69.1% underwent cam and/or pincer resection. At the time of revision, 64.7% underwent cam and/or pincer resection, with 32.4% undergoing repeat osseous work. Labral repair (18.8%) and labral debridement (14.5%) were the most frequent soft-tissue procedures performed at revision. Patients with bony correction at only index and only revision hip arthroscopy reported comparable PROMs. Overall, 1 patient underwent repeat revision arthroscopy and 13 patients (18.8%) converted to THA at a mean of 1.4 years following revision. Labral debridement (HR 9.79, 95% CI 3.25–29.5, p < 0.001) and labral repair (HR 4.56, 95% CI 1.57–13.2, p = 0.01) were associated with higher failure risk. Conclusion Revision hip arthroscopy offers symptomatic improvement for most patients, however, failure may be more common among those with incomplete osseous correction or labral debridement at revision. Attention to comprehensive bony and soft tissue management during primary and revision procedures may reduce the risk of re-revision and conversion to arthroplasty.

Abstract Purpose The purpose of this study was to evaluate changes in hip capsular height on magnetic resonance imaging (MRI) before and after hip arthroscopy and to report associated patient-reported outcomes. Methods A retrospective case series was performed of patients who underwent hip arthroscopy with both preoperative and postoperative MRI arthrogram available. Demographics including age, sex, body mass index (BMI), and laterality were collected. Capsular height was measured preoperatively and postoperatively on MRI, to determine whether intra-operative capsular elevation resulted in durably altered capsulolabral recess morphology on subsequent imaging. The primary outcome analyzed was postoperative capsular height and change from baseline. Patient-reported outcomes collected included Tegner activity score, Visual Analog Scale for pain at rest and with activity, modified Harris Hip Score (mHHS), Hip Outcome Score-Activities of Daily Living (HOS-ADL), HOS-Sports, subjective surgery outcome, and surgery satisfaction (0-10). Results Fifty hips were included with a mean age of 30.9 ± 10.9 years and mean BMI of 29.1 ± 6.3 kg/m2. There were 37 females (74.0%) with 28 right hips (56.0%). Mean time from preoperative MRI to surgery was 0.6 ± 0.7 years (range, 0.0 – 3.6 years), and from surgery to postoperative MRI was 2.5 ± 1.6 years (range, 0.2 – 6.6 years). Preoperative capsular height was 2.2 ± 3.2 mm and increased to 7.9 ± 5.4 mm postoperatively (p<0.01) (Δ 5.7 ± 6.3 mm). At a mean follow-up of 4.7 ± 1.4 years, Tegner scores improved from 3.2 ± 2.1 preoperatively to 4.6 ± 2.4 postoperatively. Mean VAS scores were 2.4 ± 2.7 at rest and 4.2 ± 2.7 with use. Mean mHHS was 72.0 ± 17.6, HOS-ADL was 81.4 ± 16.5, and HOS-Sports was 71.1 ± 28.2. Mean satisfaction (0-10) was 7.1 ± 2.5, with 83.3% of patients reporting they felt “much better” or “slightly better” after surgery. Additionally, neither postoperative capsular height nor magnitude of postoperative change in capsular height were correlated patient-report outcome scores. Conclusions Hip arthroscopy is associated with a measurable increase in capsular height on postoperative MRI, suggesting capsular elevation following intervention. These findings provide early quantitative imaging evidence demonstrating changes in capsular morphology postoperatively and highlight the need for further studies correlating capsular elevation with long-term clinical outcomes.

Abstract Background Femoral stem collars are intended to improve axial stability and load transfer following total hip arthroplasty (THA). However, substantial variability exists in collar geometry across implant systems, and how collar size and collar–calcar interaction influences femoral remodeling and the risk of mechanical complications remains incompletely understood. The purpose of this study was to determine radiographic calcar remodeling over time and to compare reoperation rates between femoral stems with constant-length collars (CLC) and size-specific collars (SSC), with the goal of better defining an optimal collar geometry. Methods A retrospective cohort study was performed using an institutional total joint registry to identify patients undergoing primary THA with either a CLC stem or an SSC stem. Radiographic measurements of collar overhang and collar-calcar gap were obtained at immediate postoperative, 3-month, and ≥2-year follow-up. Logistic regression models evaluated predictors of collar-calcar gap formation and closure. Receiver operating characteristic analysis identified a threshold for predictive gap resolution. A numerical optimization model was used to estimate the medial-to-lateral collar length that minimized absolute collar-calcar mismatch over time. Results Collar-calcar gaps were present in 12% of cases postoperatively, with resolution in 87% at final follow-up. Initial gap magnitude was the primary predictor of gap closure (OR 0.30 per mm, p < 0.001), with ROC analysis identifying an optimal cutoff of 1.54 mm for gap resolution. Progressive medial collar overhang increased over time. Optimization modeling demonstrated that the collar length minimizing absolute collar-calcar mismatch decreased from 7.5 mm at implantation to approximately 5.3 mm at final follow-up. Reoperation rates did not differ between implant designs, however occurred disproportionately in smaller CLC femoral stem sizes. Conclusion Proximal femoral remodeling following THA results in predictable thinning of the femoral calcar and progressive medial collar overhang over time. These findings suggest that collar geometry, particularly in smaller femora, should be considered relative to patient anatomy rather than implant design philosophy alone.

Abstract Background The level of femoral neck resection in total hip arthroplasty (THA) affects implant position, restoration of limb length, and the degree of cortical support available for collared cementless stems. With the increasing use of computed tomography (CT)-based planning and collared femoral stems, a clearer understanding of femoral neck and calcar morphology at the osteotomy plane is valuable. We sought to quantify cortical thickness at the planned neck resection level, characterize variability across adjacent axial levels, and determine an optimal collar length to minimize overhang and underhang. Methods We reviewed preoperative CT scans from 100 consecutive primary THAs performed by a single surgeon. Using multiplanar reconstruction, calcar cortical thickness was measured on axial images at the planned osteotomy level (0mm) and at standardized levels 5.30 mm proximal and 5.30 mm distal to that plane. At each level, thickness was recorded at 5 locations (anterior, posterior, medial, anteromedial, and posteromedial). An idealized medial-to-lateral collar length was then calculated to minimize absolute collar overhang and underhang across the cohort. Results Cortical thickness increased from proximal to distal levels, most prominently in the medial (p<0.001) and posteromedial (p<0.001) regions. Anteromedial thickness increased from the proximal level to the osteotomy plane (p=0.004) but did not increase further distally (p=0.641). Sex-based differences were limited; the only significant difference was greater anteromedial thickness in women at the proximal level (3.9 versus 3.3 mm; p=0.048). The collar length that minimized absolute overhang/underhang was 5.30 mm. Conclusion At and around the planned femoral neck osteotomy plane, medial and posteromedial cortices were thickest and increased in thickness distally, whereas anteromedial thickness plateaued, and a collar length of 5.3mm minimized overhang/underhang. These data provide an anatomic reference to inform cementless femoral stem collar geometry and optimize collar-cortical contact in primary cementless THA.

Abstract Introduction Younger, more active patients increasingly undergo total hip arthroplasty (THA) and commonly inquire about expectations and timeline regarding return to sport (RTS) and exercise. The direct anterior approach (DAA) may facilitate faster recovery and decreased instability risk, but long-term RTS data are limited. Methods A retrospective registry review identified all primary DAA THAs from 2010 and 2020. Patients who had less than five-year follow-up were excluded. Eligible patients completed a survey on preoperative and postoperative sport participation, time to RTS, and potential factors limiting RTS. A total of 886 patients (466 women and 428 men) responded to the survey. Their mean age was 62.8 years (range, 28 to 93), and their mean body mass index was 29.0 (range, 17 to 49). Results In the year prior to THA, 84% walked, 31% hiked, 27% cycled, and 11% ran. Postoperatively, 74% returned fully to prior activities and 16% returned with modifications, with 90% of these patients achieving RTS within one year. High-impact sport participation decreased from 24% preoperatively to 10% postoperatively, and running decreased from 11 to 5% (P < 0.001). Those who discontinued running most commonly cited surgeon advice (34%), fear of damaging the joint (21%), and pain (20%) as contributing factors for running cessation. Overall rates of revision were 4.5% for the running cohort and 3.2% for the non-running cohort (P = 0.651). Conclusion At a minimum five-year follow-up, most patients who underwent DAA THA successfully returned to sporting activities, typically within six months postoperatively. The majority resumed low-impact sports, while participation in high-impact activities declined. Patient counseling and fear of joint damage was a common reason for avoiding return to sport, despite mixed evidence suggesting increased risks of arthroplasty failure with high-level activities. Future prospective studies are warranted to better guide postoperative activity recommendations and clarify the long-term implications of sport participation after THA.

Abstract Background Femoral exposure is among the most challenging aspects of total hip arthroplasty (THA) through a direct anterior approach (DAA). Soft tissue releases are performed to improve exposure, although the contribution of each structure to femoral mobility is not well quantified to date. The purpose of this study was to quantify release-related femoral displacement during DAA THA. Methods Eight hips from cadaveric specimens underwent a DAA. A mechanical testing device applied 110N of anterior distraction force through a hook inserted into the proximal femur. Displacement was recorded in triplicate at baseline and after each sequential release: inferomedial capsule (A), superior capsule (B), obturator internus for left hips (C1) or piriformis for right hips (C2), piriformis for left hips (D1) or obturator internus for right hips (D2), obturator externus (E), quadratus femoris (F), tensor facia lata (G), sartorius (H), and direct head of the rectus femoris (I). Results Baseline anterior femoral mobility measured 31.7±10.1mm and changed minimally after inferomedial (30.2±9.7mm) and superior capsular release (32.8±11.1mm). Larger increases occurred with the isolated addition of obturator internus (+18.8mm, p=0.065) or piriformis (+9.5mm, p=0.024) release. Greater additional anterior femoral mobility resulted from subsequent piriformis (+41.0mm, p=0.001) or obturator internus release (+27.2mm p=0.010). Additional releases demonstrated progressively increasing anterior displacement. Conclusion Femoral exposure can be challenging and may require varying degrees of soft tissue release. This biomechanical model quantifies the displacement achieved with each sequential release through extensive mobilization and provides objective reference values to guide surgeons in obtaining safe and adequate femoral exposure.

ABSTRACT We characterize copine‐4 (CPNE4)‐IgG and report clinical associations. Among 844 samples with unclassified neural IgGs identified by mouse‐brain indirect immunofluorescence assay over 2 years, 5 samples (serum, 3; CSF, 2) from 3 patients produced a distinctive cerebrum‐restricted synaptic pattern. Protein microarray disclosed CPNE4 “top hit” in those 3 patients; specificity was confirmed by 3 CPNE4‐specific assays (confocal IFA, cell‐based, and western blot). Median onset age was 67 years (range 60–68); all had encephalitis: a brainstem syndrome during immune checkpoint inhibitor therapy for lung cancer (2) and anti‐NMDA‐receptor encephalitis accompanied by neuroectoderm‐lineage cancer (1). To date, CPNE4‐IgG has paraneoplastic encephalitis significance.

Abstract Background Detecting Histoplasma (HP) and Blastomyces (BM) antigen (Ag) in urine (U) and serum (S) is an essential diagnostic tool for these pathogens. Labs have added bronchoalveolar lavage (BAL) and cerebrospinal fluid (CSF) as additional HP and BM Ag testing sources. We evaluated the sensitivity of Ag detection in U and S in patients with detected HP or BM Ag in BAL or CSF by enzyme immunoassay (EIA). Methods 14 patients with HP or BM Ag-positive results made up the CSF cohort. The Ag concentrations were below the limit of quantification (< LoQ, N=3), above the limit of quantification (> LoQ, N=1), and 0.3 to 9.5 ng/mL (mean = 2.3 ng/mL, N=10). The BM Ag-positive in BAL group included 24 patients, with concentrations of LoQ (N=5), and 0.3 to 11.3 ng/mL (mean = 3.5 ng/mL, N=15). HP Ag-positive in BAL comprised 36 patients, with 3 LoQ, and 23 ranging from 0.8 to 16.9 ng/mL (mean = 4.7 ng/mL). All patients were checked for routine clinical HP and BM EIA Ag test results on U and S. HP BAL patients were also investigated for cross-reacting galactomannan (GM; Aspergillus EIA in S or BAL) and (1?3)-ß-d-glucan (BDG; Fungitell EIA in S) antigen test orders. Test results greater than 14 days before or after CSF or BAL Ag testing were excluded. Results 100% (14/14), 95.7% (22/23), and 83.3% (30/36) of HP/BM CSF, BM BAL, and HP BAL Ag-positive patients were also positive in U and/or S, when both additional sources were ordered, respectively. Of the 6 HP BAL patients without positive U or S results, 3 had GM and BDG testing performed. All 3 had high signal GM and/or BDG results in S and/or BAL. In conjunction with low HP Ag levels in BAL (1.0 to 1.53), these findings suggest cross-reactivity in the HP BAL Ag test. Classifying these 3 patients as HP BAL false-positive shows a positive agreement of 90.9% (30/33) between HP BAL and HP U/S. Conclusion 16 patients in the BAL cohorts were Ag-positive for HP and BM, demonstrating the inability to discriminate between these dimorphic fungi through Ag testing. HP/BM CSF Ag testing showed no increase in sensitivity when U/S were tested. Minimal increases in sensitivity were observed in BM/HP BAL versus U/S. However, false-positive results in BAL due to cross-reactivity with GM/BDG cannot be ruled out, suggesting limited utility in the invasive CSF/BAL sources.