Editorial Commentary: Most Patients With Borderline Hip Dysplasia Do Well After Hip Arthroscopy: Could Instability Be the Problem for Those Who Do Poorly?

Three-dimensional lower limb kinematics and kinetics in femoroacetabular impingement syndrome (FAIS) patients with and without borderline developmental dysplasia of the hip (BDDH) during level walking

PURPOSE

The impact of femoroacetabular impingement syndrome (FAIS) on gait has been reported; however, no studies have documented the effects of Borderline Developmental Dysplasia of the Hip (BDDH) combined with FAIS on gait. This study aimed to evaluate the kinematic and kinetic abnormalities of the lower extremities in patients with combined FAIS and BDDH during level walking.

METHODS

A total of 42 participants were included, consisting of 14 patients with FAIS + BDDH, 14 with isolated FAIS and 14 healthy controls. Full-cycle kinematic and kinetic data were collected via motion capture and force plates. Gait analysis was performed in three planes (sagittal, coronal and transverse) for the hip, knee, ankle and pelvis joints. The range of motion (ROM), kinematics and kinetics were compared across the three groups.

RESULTS

Compared with isolated FAIS patients, FAIS + BDDH patients presented a significantly greater hip flexion angle during terminal stance (P < 0.05). Moreover, the hip abduction moment was significantly reduced in the loading response and midstance phases in FAIS + BDDH patients (P < 0.05). The knee extension moment was significantly reduced during terminal stance in both FAIS groups (P < 0.05). The ankle dorsiflexion angle was significantly greater during midstance in FAIS + BDDH patients than in healthy controls, with concomitant reductions in the ankle dorsiflexion moment (P < 0.05). No significant differences were found in the range of motion (ROM) of the pelvis or hip joints and hip moment arm among the three groups (P > 0.05).

CONCLUSION

Compared with patients with isolated FAIS, patients with FAIS combined with BDDH exhibit a gait pattern characterized by biomechanical defects of the hip joint similar to developmental dysplasia of the hip (DDH), increased knee stiffness, and compensatory alterations in the ankle joint.

LEVEL OF EVIDENCE

V.

Painful Borderline Acetabular Dysplasia: What's New?

Developmental dysplasia of the hip (DDH) is a complex static-dynamic condition resulting in chronic joint instability and osteoarthritis. Borderline acetabular dysplasia refers to slightly abnormal patterns in the acetabular shape and coverage that are not within the dysplastic range. However, they can predispose to mechanical dysfunction and hip instability. Diagnosis and treatment remain controversial topics in hip preservation, with little current comparative literature to guide accurate diagnosis and treatment decision-making. Historically, the diagnosis of borderline DDH relied on assessments of the acetabular anatomy on anteroposterior pelvic radiography, most commonly the lateral central-edge angle (LCEA), with normal values ranging from 20 to 25° or, in some more recent studies, 18 to 25°. Surgical treatment decision-making debates the use of isolated hip arthroscopy or periacetabular osteotomy, considering the difficulty in determining a fundamental mechanical diagnosis (instability versus femoroacetabular impingement) in subjects with borderline DDH. Therefore, for effective surgical decision-making, the evaluation of additional bone anatomy characteristics, instability, and patients' features is essential.

The Principles of Hip Joint Preservation

The three primary factors involved in preservation of the hip joint include femoroacetabular impingement (FAI), hip dysplasia/instability, and femoral torsion abnormalities. Each of these factors affects the health of the acetabular labrum and femoroacetabular cartilage. The appropriate surgical treatments for each of these factors include arthroscopic or open femoroplasty/acetabuloplasty for FAI, periacetabular osteotomy for hip dysplasia/instability, and derotational femoral osteotomy for femoral torsion abnormalities. When evaluating patients with prearthritic hip conditions, orthopaedic surgeons should be aware of the various factors involved in hip joint preservation and, if surgery is indicated, the surgeon should be sure to address all factors that need surgical treatment rather than focusing on the commonly diagnosed issue or visible injury, for example, a labral tear. If any of these factors is ignored, the hip joint may not thrive. The purpose of this review was to explain the importance of the most common factors involved in hip joint preservation and the appropriate surgical treatments for pathology in these factors.

Risk Factors for Failure of Hip Arthroscopy in Patients With Borderline Dysplasia Include a Tönnis Angle ≥15°, Age ≥40 to 42 Years, Female Sex, Anterior Wall Index <0.35, Labral Debridement, and Preexisting Hip Osteoarthritis: A Systematic Review

PURPOSE

To systematically review the literature to determine potential risk factors for failure of hip arthroscopy (HA) in patients with borderline hip dysplasia (BHD).

METHODS

A systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines by searching PubMed, the Cochrane Library, and Embase to identify English-language clinical studies reporting on patients with BHD undergoing HA from 2003 to 2023. The search terms used were (borderline OR mild) AND hip AND (arthroscopy OR dysplasia) AND failure. The primary outcomes assessed were risk factors reported by each study for failure of a HA-only approach in patients with BHD.

RESULTS

Fourteen studies (8 Level III, 6 Level IV) met inclusion criteria, totaling 749 hips. Patient age ranged from 29.8 to 39.2 years, with a mean follow-up ranging from 24.0 to 144.0 months. The overall percentage of female patients ranged from 11.8% to 100.0%. Overall, the clinical failure rate ranged from 0 to 53.3%, and the reoperation rate ranged from 0 to 44.0%. The predominant predictors of poor outcomes after HA alone included Tönnis angle ≥15°, age ≥40 to 42 years at surgery, and female sex. Other risk factors for failure were preoperative clinical arthritis, grade 3 or 4 articular cartilage changes to the femoral head or acetabulum, an anterior wall index <0.35, and labral debridement. Revision procedures performed included revision HA (n = 88, 0-28.0%), total hip arthroplasty (n = 55, 0%-23.7%), and endoscopic shelf acetabuloplasty (n = 5, 0%-11.0%). One study included an additional 9 patients converting to either periacetabular osteotomy or total hip arthroplasty without distinguishing between the two.

CONCLUSIONS

For patients with BHD, Tönnis angle ≥15°, age ≥40 to 42 years at surgery, female sex, anterior wall index <0.35, labral debridement, and pre-existing hip osteoarthritis are common risk factors for treatment failure following isolated HA.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III-IV studies.

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.

The Principles of Hip Joint Preservation

The 3 primary factors involved with preservation of the hip joint are femoroacetabular impingement (FAI), hip dysplasia, and femoral torsion abnormalities. Each of these factors affects the health of the acetabular labrum and femoroacetabular cartilage. The appropriate surgical treatments for each of these factors include arthroscopic or open femoroplasty or acetabuloplasty for FAI, periacetabular osteotomy (PAO) for acetabular dysplasia, and de-rotational femoral osteotomy for femoral torsion abnormalities. When evaluating patients with prearthritic hip conditions, orthopaedic surgeons should be aware of the various factors involved in hip joint preservation and, if surgery is indicated, surgeons should be sure to address all factors that need surgical treatment rather than focusing on the most obvious issue or injury (e.g., a labral tear). The purpose of this infographic is to illustrate the importance of the factors involved in hip joint preservation and the appropriate treatments for pathology in any of these factors.

Outcomes and Return-to-Sports Rates in Patients With Borderline Hip Dysplasia After Periacetabular Osteotomy: A Case Series With 5-Year Follow-up

BACKGROUND

The optimal surgical approach in patients with borderline hip dysplasia (BHD) remains controversial. Both hip arthroscopy and periacetabular osteotomy (PAO) are commonly employed in this patient population. Those who participate in sports want to resume and maintain sports activities after surgery, and the ability to do so plays an important role in the choice of a treatment method. To our knowledge, no previous study has assessed return-to-sports rates and activity levels in patients with BHD after PAO.

PURPOSE

To assess return-to-sports rates and postoperative activity levels as measured by the University of California, Los Angeles (UCLA), activity scale as well as patient-reported outcome measures. Also to assess changes in sports activity both qualitatively and quantitatively as well as underlying reasons for these changes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We conducted a retrospective analysis of prospectively collected data from 55 hips in 52 patients with BHD who underwent PAO between January 2015 and June 2017. Return-to-sports rates, UCLA activity scores, International Hip Outcome Tool-12 scores, Subjective Hip Value scores, Hip disability and Osteoarthritis Outcome Score subscores, sports practiced, frequency and duration of sports activity, and postoperative changes as well as underlying reasons were recorded.

RESULTS

The mean follow-up was 62.8 ± 9.0 months. The return-to-sports rate among preoperatively active patients was 92.5%. Most patients resumed sports activity after 6 months (50%) or after 3 to 6 months (37.5%). The UCLA activity score improved significantly (from 5.2 ± 2.4 to 7.0 ± 1.8; P < .001). The International Hip Outcome Tool-12, Subjective Hip Value, and Hip disability and Osteoarthritis Outcome Score scores also improved significantly (all, P < .001). Changes in sports activity occurred in 34.5% of cases after PAO. Significantly more patients engaged in low-impact sports postoperatively. Participation in high-impact sports did not decrease significantly. Reasons for changes were both hip related and non-hip related. Quantitatively, patients were able to significantly increase both the frequency (P = .007) and duration (P = .007) of sports activity.

CONCLUSION

The return-to-sports rate in patients with BHD after PAO was high at over 92%. Most patients returned to sports after a period of 6 months or 3 to 6 months. Overall, activity levels and hip function improved after PAO. A number of patients adjusted their sports activity after PAO. Although more patients engaged in low-impact sports, participation in high-impact sports was maintained postoperatively. The results of this study may help both patients and orthopaedic surgeons in deciding on the best surgical procedure in the setting of BHD.