What the papers say

Abstract

In vitro ovine cam impingement model and its effect on acetabular cartilage

In this study Happa et al. [1] note that femoroacetabular impingement syndrome is a condition where abnormal contact occurs between the femoral head and the acetabulum, leading to chondral damage and hip osteoarthritis. To better understand and treat femoroacetabular impingement syndrome, it is crucial to establish in vitro models that mimic the condition and assess potential interventions.

Their aim, was to establish an in vitro ovine cam impingement model and assess the effectiveness of cam excision in reducing the incidence of type 3 acetabular labrum articular disruption (ALAD) (chondral flap) lesions. They conducted a controlled laboratory study.

Utilizing an ovine in vitro cam impingement model, 40 hips were subjected to testing across five groups (n = 8 per group): group 1 (control group), 750 N for 200 cycles; group 2 (cycle decrease), 750 N for 100 cycles; group 3 (load decrease), 500 N for 200 cycles; group 4 (cam excision), cam excision followed by 750 N for 200 cycles; and group 5 (halfway cam excision), 750 N for 100 cycles followed by cam excision under an additional 750 N for 100 cycles loading. Each specimen was subsequently assessed for chondral damage according to the ALAD classification, both macroscopically and microscopically.

The control group (group 1) demonstrated the highest ALAD scores (2.7 ± 0.4, 2.8 ± 0.3) compared with other groups, whereas the cam excision group (group 4) exhibited lower scores (0.5 ± 0.5, 0.7 ± 0.4) than both the cycle decrease group (group 2) (1.6 ± 0.5, 1.6 ± 0.5) and the halfway cam excision group (group 5) (1.8 ± 0.6, 2 ± 0.5) in both macroscopic and microscopic gradings. The load decrease group (group 3) (1 ± 0.5) also displayed lower scores compared with group 5 (2 ± 0.5) at histological grading.

They concluded that in vitro sheep model was established that reliably induces mechanical chondrolabral damage in the hip joint. The findings show that reducing the load results in less chondrolabral damage compared with reducing the number of cycles. Furthermore, this model emphasizes the protective effect of cam excision in the management of chondral flap lesions (ALAD type 3).

Endoscopic-assisted percutaneous fixation for displaced anterior inferior iliac spine avulsion fractures: a prospective cohort study

The authors from Italy [2] state that the anterior inferior iliac spine (AIIS) avulsion fractures commonly occur in adolescent patients during sports activities. Their aim was to systematically evaluate fracture severity and guide management, an adaptation of the Hetsroni classification system was used to categorize fractures on the basis of their displacement relative to the acetabular rim. Traditional open reduction and internal fixation have reported satisfactory consolidation rates but complications such as lateral femoral cutaneous nerve (LFCN) neuropathies, heterotopic ossifications (HO), and subspine impingement. The objectives of this work were to (i) report short- and mid-term radiographic and clinical outcomes and (ii) propose an adapted classification system based on the risk of subsequent subspine impingement. A prospective cohort study was conducted on patients with AIIS avulsion fracture with ≥1.5 cm displacement who underwent surgery between 2021 and 2024. Patients with follow-up < 6 months, displacement < 1.5 cm, comminuted fractures, or chronic fractures were excluded. Clinical outcomes, including the subspine impingement test, the modified Harris Hip Score (mHHS), and the University of California Los Angeles Score (UCLA), were evaluated at last follow-up. Postoperative complications, such as LFCN neurapraxia, HO (classified by Brooker), and surgical revisions, are reported.

In this study 11 male patients with mean age of 14.1 years (range 12.8–15.0 years) were included. Fractures were classified as type I in two patients (18.2%), type II in four patients (36.4%), and type III in five patients (45.4%). The mean surgical duration was 71.4 min (SD 17.1 min), and the average time from injury to surgery was 4.2 days (range 1–11 days). The mean fracture displacement was 18.3 mm (range 15–25 mm). Postoperative scores averaged 89.7 for mHHS (SD 3.1) and 9.7 for UCLA (SD 0.6). Patients were followed for 20.0 months (range 6–47 months, SD 13.3 months). One patient underwent open surgical revision and subsequently experienced temporary LFCN neurapraxia, HO (Brooker 1), and symptoms of subspine impingement.

They concluded that endoscopic-assisted percutaneous fixation is an effective technique for treating displaced AIIS avulsion fractures. Preliminary results suggest that this approach offers noninferior results, satisfactory outcomes, and limited complications. Further studies with long-term follow-up are needed to confirm these findings.

Evaluating outcomes and survivorship of revision arthroscopic surgery for femoroacetabular impingement compared with matched primary cases

The exponential rise in arthroscopy for femoroacetabular impingement (FAI) has led to increased revision surgery rates, although this is often an exclusion criterion from arthroscopy literature. Mullins et al. [3] examine the midterm (minimum 5-year follow-up) outcomes after revision arthroscopic correction of FAI compared with a matched control group of primary surgical cases.

Prospective outcome data, collected in a consecutive series of patients undergoing revision arthroscopic FAI correction, was retrospectively reviewed. Revision procedures were compared with a matched group of primary surgical cases. Survivorship was defined as the avoidance of total hip replacement (THR) and assessed using a Kaplan–Meier curve with the log-rank test. Regression analysis was conducted to identify predictors of THR conversion. Patient-reported outcomes (PROs) including mHHS, University of California, Los Angeles (UCLA), 36-Item Short Form Health Survey (SF36), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) preoperatively and at 5 years postoperatively were compared between the groups. The proportion of patients across groups achieving the minimal clinically important difference (MCID) was compared for each PRO. Finally, a subgroup analysis was performed to compare the outcomes of those who had their index surgery at our clinic and those who had an index procedure elsewhere. They included a total of 124 revision cases were compared with 268 primary cases. The most common indication for revision surgery was residual bony deformity. Both groups had high survivorship rates at 5 years (>90%) although revision cases did have a statistically higher conversion to THR than did primary cases (6.5% vs. 1.5%; P = .008). Increasing age and revision surgery were identified in regression analysis as predictors for THR conversion. Where THR was avoided, improvements in PROs were observed in both groups (P < .05 for all). Before surgery, revision cases reported lower scores for all PROs. At 5 years, the only statistical difference between the groups was in the distribution of mHHS scores. There were no differences in the rate of MCID achievement between groups.

Thus, the authors conclude that the residual bony deformity is the most common indication for revision arthroscopy. Revision procedures may have a lower survival than primary cases, although overall survivorship at midterm follow-up is high. Of the revision cases, 17% required further arthroscopy. Where THR is avoided, improvements in pain and function can be expected that are similar to primary surgical cases.

More is not always better-association between hip range of motion and symptom severity in patients with femoroacetabular impingement syndrome: a cross-sectional study

Restricted hip range of motion (ROM) is a common finding in patients with femoroacetabular impingement (FAI) syndrome. However Gomes et al. [4] state that the association between hip ROM and symptom severity in these individuals is unclear. They explore associations between symptom severity and hip flexion and rotation ROM in patients with FAI syndrome and determine if ROM measures can discriminate those with worse symptoms.

Data from 150 participants with FAI syndrome were analyzed. A digital inclinometer was used to measure hip flexion, internal rotation, and external rotation ROM. Symptom severity was quantified using the symptoms subscale of the international Hip Outcome Tool questionnaire (iHOT-Symptoms). Multivariable fractional polynomial analyses explored associations between hip ROM measures and symptom severity. Receiver operator characteristic curves explored the ability of ROM measurements to discriminate participants with different symptomatic states.

Smaller hip flexion ROM values were associated with worse iHOT-Symptoms scores (R² = 0.242); with the polynomial concave association attenuated at approximately 120° of hip flexion ROM. Hip internal rotation was weakly associated with iHOT-Symptoms score (R² = 0.033). Hip external rotation ROM was not associated with iHOT-Symptoms score. A hip flexion value of 107° best discriminated mild to moderate and severe symptom states (sensitivity 92%, specificity 52%).

Less hip flexion ROM was associated with worse symptoms in patients with FAI syndrome. Patients with hip flexion ROM ≥ 107° had a 15-fold decrease in the likelihood of having severe symptoms. Hip rotation ROM measures do not have a clinically meaningful association with symptom severity.

Acetabular subchondral cysts are commonly identified signs of joint degeneration and arthritis. This pathology is generally considered a relative contraindication for hip preservation surgery

In this study, Marty et al. [5] investigate the effect of arthroscopic bone grafting for the treatment of acetabular subchondral cysts. They completed a retrospective analysis of hip arthroscopies performed by the senior author between 2013 and 2021. Patients with radiologic evidence of acetabular cysts who underwent arthroscopic bone grafting, with or without subsequent periacetabular osteotomy (PAO) and/or derotational femoral osteotomy with a minimum of 2-year follow-up, were included in the analysis. Patients undergoing surgical treatment for diagnoses of slipped capital femoral epiphysis, Legg–Calves–Perthe disease, osteochondromatosis, or postdislocation syndrome, as well as patients who refused to participate in the study, were excluded. They compared the PROs for patients who underwent arthroscopic bone grafting with a case-matched control group without acetabular cysts with the same surgical route (hip arthroscopy or hip arthroscopy followed by PAO). An ‘inside-out’ arthroscopic bone grafting technique was utilized, which allowed for precise access to the cystic cavity through the articular side. We analyzed postoperative PROs at a minimum of 2 years postoperatively using the international Hip Outcome Tool (iHOT-12) and Nonarthritic Hip Score (NAHS).

Results

In total, there were 44 hips in the experimental group and 78 hips in the control group. The mean PRO interval in the experimental group was 3.4 years (range, 2–5 years postoperatively), with 20 patients reaching PROs 5 years postoperatively. The experimental group reported significant improvement of iHOT-12 and NAHS scores postoperatively. Postoperative iHOT-12 and NAHS scores did not significantly differ between groups over a 5-year follow-up interval. Radiographic evidence of cyst healing was achieved in all seven patients who underwent postoperative magnetic resonance imaging, with three cases of complete resolution.

The authors thus concluded that the acetabular subchondral cysts treated with an inside-out method of arthroscopic bone grafting in the setting of hip preservation surgery with or without PAO was associated with a significant improvement in midterm PROs, comparable with a control group of patients without acetabular cysts who did not undergo bone grafting. Results from this study support the use of arthroscopic grafting in appropriately selected patients and suggest that hip preservation is not contraindicated in patients with acetabular subchondral cysts.

Association between acetabular coverage over femoral head and rate of joint space narrowing in nonarthritic hips

This study was performed Kawai et al. [6] to investigate the association between the acetabular morphology and the joint space narrowing rate (JSNR) in the non-arthritic hip. They retrospectively reviewed standing whole-leg radiographs of patients who underwent knee arthroplasty from February 2012 to March 2020 at our institute. Patients with a history of hip surgery, Kellgren–Lawrence grade ≥ II hip osteoarthritis, or rheumatoid arthritis were excluded. The hip JSNR was measured, and the normalized JSNR (nJSNR) was calculated by calibrating the joint space width with the size of the femoral head in 395 patients (790 hips) with a mean age of 73.7 years (SD 8.6). The effects of the lateral centre-edge angle (CEA) and acetabular roof obliquity (ARO) in the standing and supine positions were examined using a multivariate regression model.

The mean JSNR and nJSNR were 0.115 mm/year (SD 0.181) and 2.451 mm/year (SD 3.956), respectively. Multivariate regressions showed that older age was associated with a larger nJSNR [standardized coefficient (SC) 0.096]. The quadratic curve approximation showed that the joint space narrowing was smallest when the CEA was approximately 31.9°. This optimal CEA was the same in the standing and supine positions. Multivariate regressions were separately performed for joints with a CEA of < 31.9° and > 31.9°. When the CEA was < 31.9°, a smaller CEA was associated with a larger nJSNR (SC 0.282). When the CEA was > 31.9°, a larger CEA was associated with a larger nJSNR (SC 0.152). The ARO was not associated with the nJSNR.

In view of the above findings, the authors felt that both insufficient coverage and over-coverage of the acetabulum over the femoral head were associated with increased joint space narrowing in hips that were nonarthritic at baseline. The effects of insufficient coverage were stronger than those of overcoverage.

Conflict of interest

None declared

References