Arthroscopic Treatment of Mild/Borderline Hip Dysplasia with Concomitant Femoroacetabular Impingement-Literature Review

Radiological predictors of outcomes in hip arthroscopy for femoroacetabular impingement

Aims

Hip arthroscopy has gained prominence as a primary surgical intervention for symptomatic femoroacetabular impingement (FAI). This study aimed to identify radiological features, and their combinations, that predict the outcome of hip arthroscopy for FAI.

Methods

A prognostic cross-sectional cohort study was conducted involving patients from a single centre who underwent hip arthroscopy between January 2013 and April 2021. Radiological metrics measured on conventional radiographs and magnetic resonance arthrography were systematically assessed. The study analyzed the relationship between these metrics and complication rates, revision rates, and patient-reported outcomes.

Results

Out of 810 identified hip arthroscopies, 359 hips were included in the study. Radiological risk factors associated with unsatisfactory outcomes after cam resection included a dysplastic posterior wall, Tönnis grade 2 or higher, and over-correction of the α angle. The presence of acetabular retroversion and dysplasia were also significant predictors for worse surgical outcomes. Notably, over-correction of both cam and pincer deformities resulted in poorer outcomes than under-correction.

Conclusion

We recommend caution in performing hip arthroscopy in patients who have three positive acetabular retroversion signs. Acetabular dysplasia with a lateral centre-edge angle of less than 20° should not be treated with isolated hip arthroscopy. Acetabular rim-trimming should be avoided in patients with borderline dysplasia, and care should be taken to avoid over-correction of a cam deformity and/or pincer deformity.

Borderline Developmental Dysplasia of the Hip With Osseous Impingement as Distinct From Femoroacetabular Impingement and Developmental Dysplasia of the Hip

Background

Borderline developmental dysplasia of the hip (BDDH) accompanied by cam deformity and subspinous impingement has been found to benefit from arthroscopic surgery. However, the research comparing BDDH combined with osseous impingement to femoroacetabular impingement (FAI) without borderline dysplasia remains limited.

Purpose/Hypothesis

To compare the clinical symptoms, intraoperative findings, and outcomes of hip arthroscopy in patients with BDDH and osseous impingement versus cam-type FAI. It was hypothesized that BDDH with osseous impingement could be classified as a distinct entity between FAI and developmental dysplasia of the hip (DDH).

Study Design

Cohort study; Level of evidence, 3.

Methods

Data were collected from patients 18 to 50 years old who underwent primary hip arthroscopy between September 2016 and October 2020. Patients were divided based on preoperative lateral center-edge angle (LCEA) into 2 groups: (1) BDDH group (LCEA 18°-25°; n = 67); and (2) cam-type FAI group without BDDH (FAI group; LCEA 25°-40° and alpha angle >55°; n = 145). Disparities in symptoms, preoperative examination, intraoperative findings and procedures, and patient-reported outcome (PRO) scores were compared.

Results

Follow-up was available for 61 (91.0%) patients in the BDDH group and 125 (86.2%) patients in the FAI group. The incidence of cam deformity in BDDH patients was 91.8%. The preoperative characteristics and intraoperative findings were similar between the groups; however, preoperative internal and external hip rotation, Tönnis angle, femoroepiphyseal acetabular roof index, labral size, capsule thickness, and percentage of ligamentum teres tear were significantly higher in the BDDH group than the FAI group, and the percentage of pain aggravating factor, cam deformity, and anterior inferior iliac spine types 2 and 3 were also significantly different between groups (P < .05 for all). The percentage of intraoperative minimal acetabuloplasty, subspinous decompression, labral repair, ligamentum teres debridement, and capsular closure was significantly higher in the BDDH group than the FAI group, while the percentage of femoroplasty was higher in the FAI group (P < .05). Pre- to postoperative improvement on PRO scores was seen in both groups.

Conclusion

Given the differences in etiology and surgical procedures between the 2 conditions, it is suggested that BDDH with osseous impingement be classified as an entity distinct from FAI and DDH (and separate from BDDH without impingement) while excluding joint instability.

Femurs in patients with hip dysplasia have fundamental shape differences compared with cam femoroacetabular impingement

Femoral deformities are common in developmental dysplasia of the hip (DDH), but decisions about how to treat them are not standardized. Of interest are deformities that may be akin to cam femoroacetabular impingement (FAI). We used three-dimensional and two-dimensional measures to clarify the similarities and differences in proximal femur shape variation among female patients with DDH (n = 68) or cam FAI (n = 60). Three-dimensional measures included femoral head asphericity, as well as shape variation using statistical shape modeling and principal component analysis (PCA). Two-dimensional measures included the α-angle, head-neck offset (HNO) and the neck-shaft angle (NSA). Significant shape variations were captured in the first five PCA modes, with the greatest shared variation between groups being the length from the lesser trochanter to the femoral head and greater trochanter height. Variations unique to DDH were irregularities at different areas of the femoral head, but not at the lateral femoral head-neck junction where variation was strong in FAI. The FAI group also had unique variations in greater trochanter shape. DDH femoral heads were less spherical, as indicated by larger sphere-fitting errors (P < 0.001). Radiographically, the DDH group had significantly smaller α-angles (P < 0.001), larger head-neck offsets (P = 0.02) and larger NSAs (P < 0.001). Both the articular and extra-articular regions of the proximal femur have distinct shape features in DDH and cam FAI that can uniquely affect the biomechanics of each disorder. Accordingly, approaches to addressing each disorder should be unique.

Staged Hip Arthroscopy with Labral Repair, Femoroplasty, and Capsular Plication Followed by Periacetabular Osteotomy for Hip Dysplasia Results in Improved Outcomes and 100% Survivorship at Minimum 2-Year Follow-Up

PURPOSE

To assess patient-reported outcomes (PROs), clinically significant outcomes (CSOs), and survivorship following staged hip arthroscopy with labral repair, femoroplasty, and capsular plication followed by periacetabular osteotomy (PAO) for the management of femoroacetabular impingement syndrome (FAIS) and hip dysplasia (lateral center edge angle ≤25°).

METHODS

A prospectively maintained database was queried to retrospectively identify patients who underwent staged primary hip arthroscopy and PAO between 1/2018-10/2021 and had a minimum 2-year follow-up. PROs collected included, Hip Outcome Score Activities of Daily Living/Sports Subscale (HOS-ADL/SS), international Hip Outcome Tool-12 item questionnaire (iHOT-12), and Visual Analog Scale for Pain (VAS Pain). CSO achievement for minimal clinical important difference (MCID) and patient acceptable symptom state (PASS) were determined through cohort specific thresholds. Rates of reoperation, including, revision hip arthroscopy and conversion to total hip arthroplasty (THA) were evaluated to determine short-term survivorship.

RESULTS

Thirty-nine hips met criteria for inclusion, of which 35 hips had minimum 2-year follow up (89.7% compliance). Mean age was 25±9.1 years and 91.7% of patients were female. Respective pre- and postoperative radiographic outcomes were: Alpha angle 59.8±5.9 to 39.7±2.6°, Tönnis angle 14.6±5.6° to -1.0±2.9°, lateral center-edge angle 16.6±5.5° to 36.6±4.6°, and anterior center-edge angle 15.6±9.1° to 36.1±3.8°, with statistically significant differences pre- to postoperatively for all (P<0.001). Patients demonstrated significant improvement in all PROs pre- to postoperatively (P ≤0.004). MCID and PASS achievement rates for any PRO were 93.9% and 78.8%, respectively. There were no revision hip surgeries or conversion to THA at a mean 2.7±1.0-year follow-up. Four patients (11.1%) underwent hardware removal. One patient (2.8%) experienced a postoperative infection treated with incision and drainage.

CONCLUSIONS

Staged hip arthroscopy and PAO for the management of hip dysplasia demonstrated improvement in PROs, high CSO achievement rates, and 100% survivorship at minimum 2-year follow-up.

Hip Labral and Capsular Repair Are Unable to Restore Distractive Stability in a Biomechanical Model

PURPOSE

To evaluate the change in hip distractive stability after a capsulotomy, labral tear, and simultaneous repair of both the capsule and the labrum in a biomechanical model.

METHODS

Ten fresh-frozen human cadaveric hips were analyzed using a materials testing system to measure the distractive force and distance required to disrupt the hip suction seal under the following conditions: (1) native intact capsule and labrum, (2) 2- or 4-cm interportal capsulotomy (IPC), (3) labral tear, (4) T extension, (5) labral repair, (6) T extension repair, and (7) IPC repair. Each specimen was retested at 0° of flexion, 45° of flexion, and 45° of flexion with 15° of internal rotation.

RESULTS

A significantly higher distractive force was required to rupture the suction seal in the intact condition compared with IPC (P = .012; 95% confidence interval [CI], 4.9-42.4); IPC and labral tear (P = .002; 95% CI, 11.3-49.4); IPC, labral tear, and T extension (P = .001; 95% CI, 13.9-51.5); IPC, labral repair, and T extension (P < .001; 95% CI, 20.8-49.7); IPC, labral repair, and T extension repair (P = .002; 95% CI, 12.5-52.4); and IPC repair, labral repair, and T extension repair (P = .01; 95% CI, 5.8-46.1). The IPC condition required a higher distractive force in isolation than when combined with a labral tear (P = .14; 95% CI, 1.2-12.0), T extension (P = .005; 95% CI, 2.8-15.3), or labral repair (P = .002; 95% CI, 4.4-18.8).

CONCLUSIONS

The distractive resistance of an intact hip capsule and labrum was not restored once the soft tissues were violated, despite labral repair with a loop technique and capsular repair with interrupted figure-of-8 sutures.

CLINICAL RELEVANCE

Time-zero complete capsular repair with concomitant labral repair may not be adequate to restore distractive hip stability after hip arthroscopy, reinforcing the use of postoperative precautions in the early postoperative period.

Basics of hip arthroscopy: Step-by-step technique

Hip arthroscopy is a surgical procedure that has a technically challenging nature, requiring advanced spatial skills and specialised instrumentation. The most common indication for hip arthroscopy is femoroacetabular impingement, which is increasing due to improved awareness and knowledge of the condition among healthcare professionals. Hip arthroscopy requires many different checkpoints from patient positioning to capsule closure to be successfully completed. Patient positioning is one of the keystones of hip arthroscopy and the probability of a surgeon achieving successful outcomes is significantly influenced by the establishment of optimal access points. The importance of the acetabular labrum and capsule has been better understood in recent years. There has been a noticeable preference towards prioritising acetabular labral repair over debridement or excision. Similarly, consistent with the literature, capsule closure restores naive hip biomechanics more successfully and improves functional outcomes following hip arthroscopy. Osteochondroplasty is a frequently employed therapeutic intervention; yet, attaining optimal osteochondroplasty outcomes might present challenges. The aim is, to restore the full perfect sphericity of the femoral head without attenuation of the head. The aim of this article is to highlight the knowledge accumulated from experiences based on previous hip arthroscopy surgeries as a solution for future troubleshooting steps. Level of Evidence: Level V.

Borderline Hip Dysplasia Is Not Associated With Significant Differences in Hip Survivorship or Patient-Reported Outcomes Following Primary Hip Arthroscopy for Femoroacetabular Impingement Syndrome: A Propensity-Matched Cohort Study

PURPOSE

To compare hip survivorship and patient-reported outcomes after primary hip arthroscopy for femoroacetabular impingement syndrome (FAIS) in patients with versus without comorbid borderline hip dysplasia (BHD) at 2-year follow-up.

METHODS

A retrospective matched-cohort study was conducted involving patients who underwent primary hip arthroscopy for FAIS with a single surgeon from 2010 to 2019. BHD was defined as lateral center edge angle (LCEA) of 20 to 25°. Subjects with BHD were matched 1:2 to controls without BHD on age, sex, body mass index, and preoperative modified Harris Hip Score (mHHS). Alpha angle, LCEA, Tönnis angle, and acetabular retroversion signs were measured on preoperative and/or postoperative hip radiographs. Patient-reported outcomes were assessed using the mHHS and the Non-Arthritic Hip Score. Hip survivorship, outcome scores, and achievement of the minimum clinically important difference were compared between groups using the Mann-Whitney U test or Fisher exact test, as appropriate. P values <.05 were considered significant.

RESULTS

Thirty-one BHD subjects (mean age 36.8 years, 71.0% female) and 62 controls (mean age 38.0 years, 71.0% female) were included. There were no significant intergroup differences in demographics or preoperative radiographic measurements besides LCEA and Tönnis angle (all P > .05). Intraoperatively, subjects with BHD were found to have significantly shorter labral tears (mean 2.6 vs 2.8 clock-face hours, P = .048), but there were no significant intergroup differences in acetabular or femoral cartilage status (all P > .05). Postoperatively, there were no significant intergroup differences in rates of revision arthroscopy (BHD 6.5% vs control 11.3%) or conversion to total hip arthroplasty (BHD 9.7% vs control 1.6%), in 2-year improvement of the mHHS and Non-Arthritic Hip Score, or in minimum clinically important difference achievement rates (all P > .05).

CONCLUSIONS

BHD is not associated with a significant difference in hip survivorship or patient-reported outcomes following primary hip arthroscopy for FAIS.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

[Hip dysplasia: What influence do age, arthrosis and concomitant diseases have on the treatment result?]

Pelvic osteotomies are an established treatment for symptomatic adult hip dysplasia with a promising long-term outcome. Results depend not only on the achieved acetabular reorientation but also on patient-factors like preoperative joint condition (degree of osteoarthritis and joint congruency) and age. Additionally, the diagnosis and appropriate therapy of impingement-associated hip deformities is essential in order to achieve good mid- and long-term outcomes. The influence of chondrolabral pathology on the outcome of pelvic osteotomies is not yet defined. Symptomatic patients with residual dysplasia after previous pelvic or acetabular osteotomies can benefit from an additional osteotomy, although results can be worse in comparison to prior unoperated joints. Obesity can make surgery more demanding and increases the complication profile of PAO, although it has no influence on the postoperative outcome. Regarding the overall prognosis after an osteotomy, the consideration of combined risk factors is superior to the concentration on individual factors alone.