Taunton, Michael

Introduction In recent years collared femoral stems have been increasingly utilized in total hip arthroplasty (THA) for their ability to improve rotational stability, metaphyseal load transfer, and prevent periprosthetic femoral fracture (PFF). While literature has demonstrated their benefit over collarless stems, the clinical and biomechanical implications of a postoperative collar–calcar gap (CCG) after implantation remain incompletely understood. Objective The purpose of this scoping review was to evaluate existing literature around CCG in primary THA. Methods A PRISMA Scoping Review literature search was conducted across Ovid MEDLINE, Embase, Cochrane CENTRAL, and Scopus databases. Studies were included if they reported CCG incidence, subsidence, remodeling, or biomechanical performance in primary THA. Two independent reviewers screened studies and extracted data, and clinical study quality was assessed using the Newcastle–Ottawa Scale. Results A total of 408 studies were identified and 11 met inclusion criteria. The incidence of postoperative CCG varied from 18.7% to 53.9%. Most gaps demonstrated closure over time (66–76%). Biomechanical and finite element studies showed improved stability, reduced micromotion, and decreased periprosthetic fracture risk when direct collar–calcar contact was achieved. In contrast, stems with persistent gaps demonstrated increased subsidence (up to 19% vs 1.3%) and biomechanical behavior comparable to collarless designs. Conclusion CCG is common following THA. The majority of gaps resolve, however biomechanical evidence demonstrates that the advantages of collared stems depend on calcar contact. Preventing CCG may optimize early implant stability, though surgical technique must balance mechanical engagement with preservation of proximal femoral bone stock.

Abstract Purpose Iliopsoas tendinitis following total hip arthroplasty (THA) has been described to result from acetabular component overhang as well as prominent femoral collars. Yet, a portion of patients experience iliopsoas tendinitis in the setting of well-positioned components. The purpose of this study was to assess anatomic factors predisposing to iliopsoas tendinitis after THA. Methods Patients with THAs performed at three academic institutions who subsequently underwent arthroscopic iliopsoas release were retrospectively reviewed from 2015 to 2025 and propensity matched in a 1:3 fashion to a control group of THAs without subsequent iliopsoas release. Controls were matched by age, surgery date, laterality, sex, surgical approach, and implanted femoral component. Patients with iliopsoas tendinitis and subsequent release (THA-IP) were evaluated for anterior acetabular component overhang and femoral collar overhang, when a collar was present. We also evaluated the absolute and relative profile of the lesser trochanter on anteroposterior radiographs, understanding that when less of the lesser trochanter is visualized, the trochanter is anatomically displaced posterolaterally, resulting in a more arduous route from the inner pelvic origin of the iliopsoas to its insertion on the femur. Results Forty-five patients (mean age: 57±11; 71% female; 19 direct anterior, 10 anterolateral, 16 posterior approach) undergoing THA-IP were analyzed and matched to 135 controls. Both groups demonstrated a median cup size of 54 mm and head size of 36 mm. Average time to iliopsoas release after THA was 4 years. Anterior cup overhang of >2 mm was present in 49% of THA-IP patients, with 18% having collared femoral components, and 9% demonstrating collar overhang of >2 mm. Overall, 19 THA-IP patients had <2 mm of cup and collar overhang and 26 patients had >2 mm of overhang. THA-IP patients with <2 mm of cup and collar overhang had significantly greater relative posterolateralization of the lesser trochanter compared to those with overhang of >2 mm (p=0.010) and to controls (p=0.037). Conclusion Visualizing “Less of the Lesser” on anteroposterior hip radiographs and associated posterolateralization of the lesser trochanter may be an anatomic risk factor for iliopsoas tendinitis following THA, even in the presence of satisfactorily positioned components.

Abstract Introduction Understanding factors that impact outcomes of total hip arthroplasty (THA) can aid clinical decision-making and patient counselling. The purpose of this study was to investigate functional outcomes, complications, and reoperation rates among patients undergoing primary THA after hip arthroscopy (HA-THA) compared to a matched cohort of primary THA patients without prior arthroscopy (THA-only). Methods A retrospective review was performed to identify all patients who underwent primary THA after prior hip arthroscopy from 2009-2022 at a single institution. Patients with a history of revision arthroscopy were excluded. Cases were propensity-matched with primary THA controls in a 1:4 ratio by age at time of THA, sex, body mass index, surgical approach, and year of surgery. At minimum 2-year follow-up, patient-reported outcomes (PROs) including Forgotten Joint Score (FJS), Modified Harris Hip Score (mHHS), Hip Disability and Osteoarthritis Outcome Score Pain (HOOS pain), and Visual Analog Pain Scale (VAS) were analyzed. Results Sixty-three hips in 60 patients (age: 47.3±9.4 years, BMI: 29.8±6.2 kg/m2) were matched to 252 THA-only hips, with patients converting to THA at a mean 3.1 years (range 0.3-10.3) following hip arthroscopy. While both HA-THA and THA patients demonstrated significant (p<0.001) postoperative improvements in PROs, HA-THA patients reported significantly lower postoperative FJS, mHHS, HOOS pain, and VAS pain scores (p<0.001) as compared to THA-only controls. At mean 6.6±3.2 years follow-up, HA-THA patients with preoperative Tönnis grades 2-3 reported significantly increased FJS, mHHS, and HOOS pain compared to those with preoperative Tönnis grades of 0-1 (p≤0.03). Additionally, HA-THA patients with preoperative Tönnis grades 0-1 exhibited worse PROs (p<0.001) as compared to THA-only controls. While there were no differences in complication rates between HA-THA patients and THA-only controls (8% vs. 5%, p=0.49), all-cause reoperation was greater amongst HA-THA patients compared to THA-only (10% vs. 2%, p=0.01). Conclusion While improved compared to preoperatively, patients undergoing THA after prior hip arthroscopy demonstrated inferior outcomes at mid-term follow up as compared to a demographically age-matched cohort without prior arthroscopy. When considering conversion to THA following arthroscopy, clinicians should consider counseling patients regarding improved outcomes in the setting of advanced radiographic osteoarthritis, and potentially increased all-cause reoperation.