Mild or Borderline Hip Dysplasia: Are We Characterizing Hips With a Lateral Center-Edge Angle Between 18° and 25° Appropriately?

Risk Factors for Failure of Hip Arthroscopy in Patients with Borderline Dysplasia include a Tönnis angle ≥ 15 degrees, Age ≥ 40-42 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 BHD patients.

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 females 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 following HA alone included Tönnis angle ≥ 15°, age ≥ 40-42 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 (AWI) < 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 PAO or total hip arthroplasty (THA) without distinguishing between the two.

CONCLUSION

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

LEVEL OF EVIDENCE

IV, systematic review of level III-IV studies.

Hip shelf acetabuloplasty in borderline dysplasia, an alternative between Periacetabular Osteotomy and arthroscopic procedures

PURPOSE

Surgical treatments for symptomatic borderline dysplastic hips (Lateral Center-Edge Angle: LCEA 18-25°) remain challenging, instability being the primary issue. Currently, treatment options include arthroscopic procedures or peri-acetabular osteotomy (PAO). Although the popularity of the acetabular shelf bone block has declined in favor of PAO, it may still be relevant as a hip joint stabilizer and coverage area, rather than for increasing coverage area by cartilage. We analyzed clinical and radiographic outcomes of 23 borderline hips after undergoing shelf procedure with a minimum follow-up of two years.

METHODS

This is a retrospective descriptive study. Clinical evaluations (modified Harris Hip Score: mHHS, Non-Arthritic Hip Score: NAHS, International Hip Outcome Tool: iHOT12) and radiographic assessments were performed before and after surgery. We collected data on revision surgery rates, associated surgical procedures (labrum, impingement), complications, arthrosis progression, and conversion to total hip replacement (THR).

RESULTS

The mean LCEA was 21°, and the mean follow-up period was five years (2 to 14 years). Clinical scores showed significant improvement at the last follow-up, mHHS increasing from 47 to 72 (p < 0.001), NAHS from 42 to 68 (p < 0.001), iHOT12 from 28 to 52 (p < 0.001), and pain levels decreasing from 7 to 3. Revision surgery rate was 13%, and complication rate was 8%. No osteoarthritis beyond Tönnis grade 2, and no cases required conversion to THR.

CONCLUSION

Arthroscopic procedures and PAO have shown promising results in the treatment of borderline hips. The hip shelf procedure appears to be a simple and effective treatment for stabilizing borderline hips, with favorable outcomes for 80% of patients and a low rate of arthritic progression. Shelf procedure could be a valuable addition to the therapeutic options for painful borderline dysplasia of the hip.

How to start with hip arthroscopy in a safe and effective manner, using an evidence-based approach

Hip arthroscopy is a rapidly evolving field in orthopedics, offering diagnostic and therapeutic benefits for a range of hip pathologies. This review outlines a comprehensive guide to initiating hip arthroscopy safely and effectively using evidence-based practices. Optimal surgical outcomes depend on correct indications for surgery, in particular in the presence of borderline dysplasia and degenerative joint diseases. Proper patient counseling and setting realistic expectations are crucial for satisfactory outcomes and recovery. Physical examination, radiographs, MRI, and CT scans are essential for accurate diagnosis. In case of diagnostic uncertainty, the use of intra-articular injections can help confirm the diagnosis before surgery. Techniques for hip arthroscopy include central compartment first, peripheral compartment first, and outside-in approaches. Each technique has advantages, and the optimal approach depends on the specific case. Finally, Proper operating room setup, meticulous patient positioning, and precise portal placement are critical for a successful procedure. A thorough understanding of the safe zone anatomy for portal placement is essential to minimize the risk of neurovascular complications. In conclusion, this manuscript provides a detailed, evidence-based framework for starting hip arthroscopy, emphasizing the importance of technical proficiency, patient selection, and a multidisciplinary approach to ensure patient safety and procedure efficacy.

Patients With Dysplasia Achieve Similar Outcomes and Survivorship to Nondysplastic Patients 10 Years After Hip Arthroscopy for Femoroacetabular Impingement

PURPOSE

To determine the long-term outcomes of hip arthroscopy (HA) for femoroacetabular impingement (FAI) in the presence of concomitant lateral rim dysplasia compared with a matched control group.

METHODS

Patients undergoing HA between January 2009 and October 2013 with minimum 10-year follow-up were reviewed. The inclusion criteria consisted of patients undergoing HA for FAI with evidence of lateral rim dysplasia (lateral-center edge angle [LCEA] < 25°). Patients with lateral rim dysplasia were matched to patients with an LCEA greater than 30° based on sex, Tönnis grade, and age. Outcomes included survival (avoidance of total hip replacement [THR]), repeated HA, and patient-reported outcomes (PROs). Survivorship was assessed using a Kaplan-Meier curve and log rank test, whereas revision rates between groups were assessed using χ2 analysis. Between- and within-group analyses of PROs were conducted using the Mann-Whitney U test and Wilcoxon signed rank test, respectively. The proportion of cases achieving the patient acceptable symptom state was compared between groups using χ2 analysis.

RESULTS

This study comprised 46 dysplasia cases and 90 control cases. There was no statistically significant difference between groups in baseline metrics apart from the LCEA (P < .001), Sharp angle (P < .001), and Tönnis angle (P < .001). By 10 years postoperatively, 9% of dysplasia cases and 4% of control cases underwent conversion to THR. There was no statistically significant difference between groups in survival or revision rates. Both groups reported improvements in PROs, and there was no difference between PRO scores at either time point. Excluding cases that underwent THR, 84% and 83% of dysplasia and control cases, respectively, achieved the patient acceptable symptom state.

CONCLUSIONS

HA for symptomatic FAI is a successful treatment in cases in which dysplasia is present. Low complication rates, comparable outcomes to cases without lateral rim dysplasia, and a high survivorship rate of 91% at minimum 10-year follow-up are observed. Increasing Tönnis angle preoperatively may increase the risk of THR conversion.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.

The role of different acetabular morphologies on patient-reported outcomes following periacetabular osteotomy in borderline hip dysplasia

INTRODUCTION

The treatment option for borderline hip dysplasia (BHD) includes hip arthroscopy and periacetabular osteotomy (PAO). To the present day the controversial discussion remains, which intervention to prefer. Literature reports supporting an educated choice are scare, based on small patient cohorts and do not address the variability of acetabular morphology. Consequently, we intended to report PAO outcomes, from patients diagnosed with BHD, dependent on acetabular morphology, in a large patient cohort and aimed to define risk factors for poor clinical results and patient satisfaction.

MATERIALS AND METHODS

A prospective monocentre study was conducted. Patients enrolled underwent PAO for symptomatic BHD (LCEA, 18°-25°). A total of 107 hips were included with 94 complete data sets were available for evaluation with a minimum follow-up of 1 year and a mean follow-up of 2.3 years. The mean age was 31 ± 8.2 years, and 81.3% were female. As the primary outcome measure, we utilized the modified Harris hip score (mHHS) with minimal clinically important change (MCID) of eight to define clinical failure. Results were compared after a comprehensive radiographic assessment distinguishing between lateral deficient vs. anterior/posterolateral deficient acetabular and stable vs. unstable hip joints.

RESULTS

Overall, clinical success was achieved in 91.5% of patients and the mHHS improved significantly (52 vs. 84.7, p < 0.001). Eight hips failed to achieve the MCID and four had radiographic signs of overcorrection. Comparing variable joint morphologies, the rate of clinical success was higher in patients with an anterior/posterolateral deficient acetabular covarage compared to lateral deficient acetabular (95.2% vs. 90.4%). tThe highest rate of clinical failure was recorded in unstable hip joints (85.7% vs. 92.5% in stable hips).

CONCLUSIONS

This study demonstrates that PAO is an effective means to treat symptomatic BHD with variable acetabular morphologies, achieving a clinical success in 91.5% of all patients. To maintain a high level of safety and patient satisfaction technical accuracy appears crucial.

Editorial Commentary: Revision Hip Arthroscopy in Patients With Borderline Dysplasia Has a Role: Indications Are Narrow Versus Periacetabular Osteotomy

Hip arthroscopy (HA) is preferred for surgical management of femoroacetabular impingement syndrome, whereas periacetabular osteotomy (PAO) is the gold standard for frank developmental hip dysplasia in young adults. Borderline hip dysplasia (BHD) is a conundrum, with data supporting the use of either or both, not to mention that BHD is defined by varying lateral center-edge angle thresholds between 18° and 25° or 20° and 25° and features generalized ligamentous laxity and variations in acetabular and femoral version. That said, HA for BDH has been shown to have 10-year survivorship of 82%. In a revision situation after HA in patients with BHD, PAO seems a logical next step, but HA may be indicated under narrow indications. From a technical standpoint, capsular preservation, labral function restoration, and avoiding acetabular rim over-resection are key points when performing HA in BHD. Most important, particularly in the revision setting, is to determine the root cause of failure. Primarily, instability-driven symptoms are an indication for PAO.

Noninterportal capsulotomy of hip arthroscopy showed improved outcomes in borderline hip dysplasia: A retrospective study with minimum 2-year follow-up

PURPOSE

The present study aimed to evaluate the functional outcomes of hip arthroscopy using a noninterportal capsulotomy technique to address labral tears in patients with borderline hip dysplasia (BHD). Additionally, we also compared these outcomes with those of patients with BHD who underwent the standard repaired interportal capsulotomy (RIPC) arthroscopy.

METHODS

Data from patients with BHD were retrieved from a database of patients who underwent arthroscopic hip surgery with noninterportal capsulotomy or RIPC to treat labral tears between January 2014 and December 2020. Data collected included both pre- and postoperative patient-reported outcomes (PROs).

RESULTS

A total of 58 patients (noninterportal capsulotomy, n = 37; RIPC, n = 21) with a mean age of 30.9 ± 5.6 and 28.6 ± 5.5 years, respectively, met the inclusion criteria. All of the patients underwent a minimal 2-year follow-up. The mean lateral centre-edge angle was 23.3 ± 1.2° in the noninterportal capsulotomy group and 23.7 ± 1.0° in the RIPC group, with no significant difference. The PROs improved from the preoperative to the latest follow-up, with a p < 0.001. There were no differences between the groups.

CONCLUSION

Using strict patient selection criteria, hip arthroscopy with noninterportal capsulotomy demonstrated significant pre- to postoperative improvements in patients with BHD and achieved results comparable to those from hip arthroscopy with RIPC.

LEVEL OF EVIDENCE

Level III.

Primary and Revision Hip Arthroscopy in Borderline Hip Dysplasia Shows Comparable Outcomes at a Minimum 5-Year Follow-Up

PURPOSE

To compare patient-reported outcomes (PROs), achievement of clinically significant outcomes, and reoperation-free survivorship between primary and revision hip arthroscopy (HA) for femoroacetabular impingement syndrome (FAIS) in propensity-matched borderline hip dysplasia (BHD) patients at a minimum 5-year follow-up.

METHODS

Patients with BHD, characterized by a lateral center-edge angle 18° to 25°, who underwent HA for FAIS with capsular repair by a single surgeon between January 2012 and June 2018 with a minimum 5-year follow-up were identified. Cases of revision HA were propensity-matched 1:2 to cases of primary HA, controlling for age, sex, and body mass index. A 1:2 ratio was chosen to maximize the number of included patients. Collected PROs included Hip Outcome Score-Activities of Daily Living and Sport Subscales, International Hip Outcome Score 12, modified Harris Hip Score, and Visual Analog Scale for Pain. Achievement of minimal clinically important difference, patient acceptable symptom state, and substantial clinical benefit for any measured PRO was compared between groups along with reoperation-free survivorship using Kaplan-Meier analysis.

RESULTS

Thirty-six revision HA hips (34 patients) were propensity-matched to 72 primary HA hips (70 patients). The groups were similar in age (31.5 ± 10.3 years vs 30.5 ± 11.2, P = .669), sex (69.4% female vs 70.8%, P = .656), and body mass index (25.7 ± 4.0 vs 25.5 ± 3.7, P = .849). The revision group showed a greater prevalence of prolonged preoperative pain (50.0% vs 27.8%, P = .032) compared with the primary group. A significant improvement in all PROs was observed for both groups with comparable PROs preoperatively and at the 5-year follow-up between groups (P ≥ .086). The revision and primary groups showed comparable minimal clinically important difference (95.0% vs 95.7%, P ≥ .999), patient acceptable symptom state (80.0% vs 83.6%, P = .757), and substantial clinical benefit (62.5% vs 70.7%, P = .603) achievement for any PRO. Comparable reoperation-free survivorship was observed (P = .151).

CONCLUSIONS

Propensity-matched patients with BHD undergoing primary and revision hip arthroscopy for FAIS achieved similar minimum 5-year PROs, clinically significant outcomes, and reoperation-free survivorship.

LEVEL OF EVIDENCE

Level III, retrospective comparative case series.

Outcomes of Flexibility Sport Athletes With Borderline Hip Dysplasia After Hip Arthroscopy for Femoroacetabular Impingement Syndrome: A Propensity-Matched Analysis at Minimum 2-Year Follow-up

BACKGROUND

Hip arthroscopy has proved successful in treating femoroacetabular impingement syndrome (FAIS) in patients with and without borderline hip dysplasia (BHD). Despite a high prevalence of BHD in patients who participate in sports with high flexibility requirements, a paucity of literature evaluates the efficacy of hip arthroscopy in treating FAIS in flexibility sport athletes with BHD.

PURPOSE

To compare minimum 2-year patient-reported outcomes (PROs) and achievement of clinically significant outcomes in flexibility sport athletes with BHD undergoing primary hip arthroscopy for FAIS with capsular plication with results in flexibility sport athletes without dysplasia.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data were prospectively collected for patients undergoing primary hip arthroscopy for FAIS with BHD, defined as a lateral center-edge angle of 18° to 25°, who reported participation in a sport with a high flexibility requirement, including dance, gymnastics, figure skating, yoga, cheerleading, and martial arts, according to previous literature. These patients were matched 1:2 to flexibility sport athletes without dysplasia, controlling for age, sex, and body mass index. Preoperative and minimum 2-year postoperative PROs were collected and compared between groups. Cohort-specific minimal clinically important difference and patient acceptable symptom state achievement was compared between groups.

RESULTS

In total, 52 flexibility sport athletes with BHD were matched to 104 flexibility sport athletes without BHD. Both groups showed similar sport participation (P = .874) and a similar level of competition (P = .877). Preoperative lateral center-edge angle (22.2°± 1.6° vs 31.5°± 3.9°; P < .001) and Tönnis angle (10.9°± 3.7° vs 5.8°± 4.4°; P < .001) differed between groups. Capsular plication was performed in all cases. Both groups achieved significant improvement in all PROs (P < .001) with no differences in postoperative PROs between groups (P≥ .147). High minimal clinically important difference (BHD group: 95.7%; control group: 94.8%) and patient acceptable symptom state (BHD group: 71.7%; control group: 72.2%) achievement for any PRO was observed with no differences between groups (P≥ .835).

CONCLUSION

Flexibility sport athletes with BHD achieved similar outcomes as those of flexibility sport athletes without BHD after hip arthroscopy for FAIS with capsular plication.

No Difference in Patient-Reported Outcomes for Periacetabular Osteotomy and Hip Arthroscopy With Capsular Plication in the Setting of Borderline Hip Dysplasia: A Propensity-Matched Multicenter Study With Minimum 5-Year Follow-Up

PURPOSE

To compare minimum 5-year patient-reported outcome measures after hip arthroscopy (HA) and periacetabular osteotomy (PAO) for borderline hip dysplasia.

METHODS

Hips with a lateral center-edge angle (LCEA) between 18° and less than 25° that underwent either PAO or HA were selected from 2 institutions. The exclusion criteria were as follows: LCEA less than 18°, Tönnis osteoarthritis grade greater than 1, prior hip surgical procedures, active inflammatory disease, Workers' Compensation, and concomitant surgery. Patients underwent propensity matching based on age, sex, body mass index, and Tönnis osteoarthritis grade. Patient-reported outcome measures included the modified Harris Hip Score, as well as calculation of the minimal clinically important difference, patient acceptable symptom state, and maximum outcome improvement satisfaction threshold. Preoperative radiographic predictors included comparison of the Femoro-epiphyseal Acetabular Roof index and ligamentum teres lesions.

RESULTS

A total of 28 PAO patients underwent propensity matching to 49 HA patients. The 2 groups were similar in terms of mean age, sex, preoperative body mass index, and LCEA. The PAO group had a longer mean follow-up period (95.8 months vs 81.3 months, P = .001). The mean Femoro-epiphyseal Acetabular Roof index was significantly lower preoperatively in the HA group (P < .001). The 2 groups showed similar and significant improvements in the mean modified Harris Hip Score from preoperatively to latest follow-up (P < .001). The relative risk of subsequent surgery in the PAO group was 3.49 (P = .024), mostly attributed to hardware removal (25%). The revision rate was 3.6% in the PAO group and 8.2% in the HA group (P = .65). One patient in the PAO group required revision HA for intra-articular adhesions. Three of the patients requiring revision in the HA group underwent PAO because of persistent pain, and one underwent revision HA alone. Conversion to total hip arthroplasty was required in 1 patient in the HA group and no patients in the PAO group.

CONCLUSIONS

Both PAO and HA with capsular plication provide borderline hip dysplasia patients with clinically significant improvements and low revision rates at a minimum of 5 years postoperatively.

LEVEL OF EVIDENCE

Level III, retrospective, comparative therapeutic trial.

Ligamentum Teres Tears and Increased Combined Anteversion Are Associated With Hip Microinstability in Patients With Borderline Dysplasia

PURPOSE

To investigate the differences in the prevalence of ligamentum teres (LT) tears and other radiographic measurements in borderline dysplasia of the hip (BDDH) with/without microinstability and to evaluate the associations between these imaging findings and the prevalence of microinstability in patients with BDDH.

METHODS

This was a retrospective study of symptomatic patients with BDDH (18° ≤ lateral center-edge angle <25°) treated with arthroscopy in our hospital between January 2016 and December 2021. These patients were divided into the BDDH with microinstability (mBDDH) group and the stable BDDH (nBDDH) group. The radiographic parameters associated with hip joint stability, such as the state of LT, acetabular versions, femoral neck version, Tönnis angle, combined anteversions, and anterior/posterior acetabular coverage, were reviewed and analyzed.

RESULTS

There were 54 patients (49 female/5 male, 26.7 ± 6.9 years) in the mBDDH group and 81 patients (74 female/7 male, 27.2 ± 7.7 years) in the nBDDH group. The mBDDH group had greater LT tear (43/54 vs 5/81) and general laxity rates, increased femoral neck version, acetabular version and combined anteversion (52.4 ± 5.9 vs 41.5 ± 7.1 at 3-o'clock level) than the nBDDH group. Binary logistic regression showed that LT tears (odds ratio 6.32, 95% confidence interval 1.38-28.8; P = .02; R2 = .458) and combined anteversion at the 3-o'clock level (odds ratio 1.42, 95% confidence interval 1.09-1.84; P < .01; R2 = .458) were independent predictors of microinstability in patients with BDDH. The cutoff value of combined anteversion at 3-o'clock level was 49.5°. In addition, LT tear was correlated with increased combined anteversion at 3-o'clock level in patients with BDDH (P < .01, η2 = 0.29).

CONCLUSIONS

LT tears and increased combined anteversion at the 3-o'clock level on the acetabular clockface were associated with hip microinstability in patients with BDDH, suggesting that patients with BDDH and LT tears might have a greater prevalence of anterior microinstability.

LEVEL OF EVIDENCE

Level III, case‒control study.

Non-Operative Rehabilitation Principles for Use in Individuals with Acetabular Dysplasia: A North American Based Delphi Study

Background

Acetabular dysplasia (AD) is defined as a structurally deficient acetabulum and is a well-recognized cause of hip pain in young adults. While treatment of severe AD with a periacetabular osteotomy has demonstrated good long-term outcomes, a trial of non-operative management is often recommended in this population. This may be especially true in patients with milder deformities. Currently, there is a paucity of research pertaining to non-operative management of individuals with AD.

Purpose

To present expert-driven non-operative rehabilitation guidelines for use in individuals with AD.

Study Design

Delphi study.

Methods

A panel of 15 physiotherapists from North America who were identified as experts in non-operative rehabilitation of individuals with AD by a high-volume hip preservation surgeon participated in this Delphi study. Panelists were presented with 16 questions regarding evaluation and treatment principles of individuals with AD. A three-step Delphi method was utilized to establish consensus on non-operative rehabilitation principles for individuals presenting with AD.

Results

Total (100%) participation was achieved for all three survey rounds. Consensus, defined a piori as > 75%, was reached for 16/16 questions regarding evaluation principles, activity modifications, appropriate therapeutic exercise progression, return to activity/sport criteria, and indications for physician referral.

Conclusion

This North American based Delphi study presents expert-based consensus on non-operative rehabilitation principles for use in individuals with AD. Establishing guidelines for non-operative management in this population will help reduce practice variation and is the first step in stratifying individuals who would benefit from non-operative management. Future research should focus on patient-reported outcomes and rate of subsequent surgical intervention to determine the success of the guidelines reported in this study.

Level of Evidence

Level V.

Does hip muscle strength and functional performance differ between football players with and without hip dysplasia?

OBJECTIVE

To compare hip muscle strength and functional performance in football players with and without hip dysplasia and investigate if the relationships were modified by sex.

DESIGN

Cross-sectional study.

METHODS

This study compared football players with hip dysplasia (HD group) and without hip dysplasia (control group). Hip muscle strength (Nm/kg) and functional task performance were assessed in both groups. Linear regression with generalized estimating equations were used to assess differences between groups. Sex was assessed as a potential effect modifier.

RESULTS

101 football players were included (HD group, n = 50, control group, n = 51). There was no difference in hip muscle strength or functional performance between the HD group and the control group. Results ranged from hip extension strength (Estimate -0.13.95%CI: 0.29 to 0.02, P = 0.087) to hip external rotation strength (Estimate 0.00.95%CI: 0.05 to 0.05, P = 0.918). No relationships were modified by sex or age.

CONCLUSIONS

Similar levels of hip muscle strength and functional performance were found in active football players with and without hip dysplasia. These findings differ from other studies. This may be due to our cohort having less advanced hip dysplasia than the surgical populations that have been previously investigated, or due to a beneficial effect of football participation on muscle strength and functional performance in people with hip dysplasia.

Treatment of borderline hip dysplasia with triple pelvic osteotomy: preoperative values of acetabular index and lateral center edge angle can indicate overcorrection

INTRODUCTION

After pelvic osteotomy for the treatment of symptomatic hip dysplasia, the longevity of the hip joint can be compromised by acetabular overcorrection. This iatrogenic pincer-type deformity is considered to be one of the major risk factors for persistent pain and progressing osteoarthritis. There is evidence that acetabula in the borderline range, defined by a lateral center edge angle (LCEA) between 18° and 25°, are more delicate to be orientated physiologically. The aim of this study was to assess the quality of acetabular orientation by triple pelvic osteotomy (TPO), established by Tönnis and Kalchschmidt, especially with respect to acetabular overcorrection.

MATERIALS AND METHODS

A retrospective examination on 368 consecutive hips treated with TPOs was conducted. On the preoperative pelvic radiograph and the radiographic control 5 days after surgery, LCEA, acetabular index (AI), and anterior (AWI) and posterior wall index (PWI) were measured. According to the above-mentioned definition, the hips were divided into a borderline (n = 196) and a dysplastic (n = 172) group. Acetabular overcorrection was defined as when LCEA exceeded 35°, AI was below 0° and AWI exceeded 0.60, postoperatively. The postoperative occurrence of a relevant femoroacetabular impingement was correlated to these thresholds. Statistics comprised a priori power analysis, correlation analyses and receiver operating characteristics (ROC).

RESULTS

In the borderline group, in 64 hips (32.7%), LCEA and AI indicated lateral overcorrection. In the dysplastic group, in 14 hips (8.1%), solely AI indicated overcorrection. In none of the hips, relevant anterior overcorrection was detected since AWI never exceeded 0.60. Chi-square test demonstrated a significant correlation between the occurrence of a postoperative femoroacetabular impingement and LCEA exceeding 35°, as well as AI below 0° (p < 0.001, resp.). Bravais-Pearson's analysis showed a significant correlation between the pre- and postoperative values of all parameters in the borderline and the dysplasia group (p < 0.001). Thus, ROC analysis could be performed and provided preoperative cutoff values for LCEA (23°) and AI (12.5°), hinting at postoperative overcorrection.

CONCLUSION

The comparison of radiographic parameters after TPO showed a considerably greater percentage of laterally overcorrected acetabula in the borderline hips than in the dysplastic hips. According to the wall indices, anterior overcorrection was not observed. ROC analysis anticipated unfavorable lateral overcorrection when preoperative LCEA was above 23° and AI below 12.5°. These findings should sensitize the surgeon to the delicate acetabular correction in borderline dysplastic hips.

Birmingham Royal Orthopaedic Hospital (BROH) Femoral Offset-An Ancillary Measure of Adult Dysplasia of the Hip

Introduction  Adult dysplasia of the hip (ADH) is a disorder of abnormal development of the hip joint resulting in a shallow acetabulum and uncovering of the femoral head. Several radiological measurements such as the Tönnis angle (acetabular index), lateral center edge angle of Wiberg, and cross-sectional imaging parameters exist to calculate hip dysplasia. Aims  The aim of this article was to describe a new ancillary linear measure of ADH on cross-sectional imaging, the Birmingham Royal Orthopaedic Hospital (BROH) Femoral offset. Patients and Methods  Anteroposterior radiographs of the pelvis and computed tomography imaging of 100 consecutive patients with suspected hip dysplasia were reviewed. Demographic details and clinical indications were recorded. Tönnis angle was utilized to measure hip slope on radiographs and the BROH femoral offset was calculated for each patient. Student's t -test and one-way analysis of variance (ANOVA) were performed. Intraclass correlation coefficient analysis was evaluated to assess the reliability between observers. Results  There was a total of 100 patients (128 hips) included in the study (60 with normal Tönnis angle, 53 had dysplasia, and 15 had decreased Tönnis angle). The average BROH femoral offset in the dysplastic cohort was increased in comparison to the normal cohort with a statistically significant p -Value of 0.0001. The p -value was 0.00031 on ANOVA. The BROH femoral offset calculation revealed good intra- and interobserver reliability of 0.9 and 0.9, respectively. Conclusion  The BROH femoral offset can be an additional index for measuring ADH that is easier to calculate, and reproducible with good intra- and inter-observer reliability on cross-sectional imaging.

Improved Identification of Adolescent Hip Dysplasia Using a Screening Method Based on Lateral Center Edge Angle Measurements

BACKGROUND

In addition to the clinical exam, several quantitative measurement tools are performed on pelvic radiographs in the assessment of adolescent hip dysplasia at most dedicated pediatric hip preservation clinics, with the most commonly used measurement called the lateral center edge angle (LCEA). However, most pediatric radiologists do not use these quantitative measuring tools and instead make the diagnosis of adolescent hip dysplasia based on subjective review.

OBJECTIVE

The purpose of this study is to determine the additive value of a measurement-based diagnosis of adolescent hip dysplasia using LCEA versus subjective radiographic interpretation by pediatric radiologists.

METHODS

A review of pelvic radiographs for the binomial diagnosis of hip dysplasia was performed by four pediatric radiologists (two general, two musculoskeletal). The review included 97 pelvic AP radiographs (mean age 14.4 years [range 10-20 years], 81% female) for a total of 194 hips (58 cases of adolescent hip dysplasia and 136 normal) all of whom were evaluated in a tertiary care pediatric subspecialty hip preservation clinic. Subjective radiographic interpretation of each hip for a binomial diagnosis of hip dysplasia was performed. 2 weeks later and without knowledge of the subjective radiographic interpretation results, the same review was performed with LCEA measurement and a diagnosis of hip dysplasia made when LCEA angles were under 18 degrees. A comparison of sensitivity/specificity between methods per reader was conducted. A comparison of accuracy between methods for all readers combined was performed.

RESULTS

For all four reviewers, the sensitivity of subjective versus LCEA measurement-based diagnosis of hip dysplasia was 54-67% (average 58%) versus 64-72% (average 67%), respectively, and specificity was 87-95% (average 90%) versus 89-94% (average 92%), respectively. All four readers demonstrated an intra-reader trend for improvement in the diagnosis of adolescent hip dysplasia after the addition of LCEA measurements but was only statistically significant in one of the four readers. The combined accuracy of all four readers for subjective and LCEA measurement-based interpretation was 81% and 85%, respectively with p = 0.006.

CONCLUSION

Compared with subjective interpretation, LCEA measurements demonstrate increased diagnostic accuracy amongst pediatric radiologists for the correct diagnosis of adolescent hip dysplasia.

Posterior Hip Impingement at Maximal Hip Extension in Female Patients With Increased Femoral Version or Increased McKibbin Index and Its Effect on Sports Performance

Background

The location of posterior hip impingement at maximal extension in patients with posterior femoroacetabular impingement (FAI) is unclear.

Purpose

To investigate the frequency and area of impingement at maximal hip extension and at 10° and 20° of extension in female patients with increased femoral version (FV) and posterior hip pain.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Osseous patient-specific 3-dimensional (3D) models were generated of 50 hips (37 female patients, 3D computed tomography) with a positive posterior impingement test and increased FV (defined as >35°). The McKibbin index (combined version) was calculated as the sum of FV and acetabular version (AV). Subgroups of patients with an increased McKibbin index >70° (24 hips) and FV >50° (20 hips) were analyzed. A control group of female participants (10 hips) had normal FV, normal AV, and no valgus deformity (neck-shaft angle, <139°). Validated 3D collision detection software was used for simulation of osseous impingement-free hip extension (no rotation).

Results

The mean impingement-free maximal hip extension was significantly lower in patients with FV >35° compared with the control group (15° ± 15° vs 55° ± 19°; P < .001). At maximal hip extension, 78% of patients with FV >35° had osseous posterior extra-articular ischiofemoral hip impingement. At 20° of extension, the frequency of posterior extra-articular ischiofemoral impingement was significantly higher for patients with a McKibbin index >70° (83%) and for patients with FV >35° (76%) than for controls (0%) (P < .001 for both). There was a significant correlation between maximal extension (no rotation) and FV (r = 0.46; P < .001) as well as between impingement area at 20° of extension (external rotation [ER], 0°) and McKibbin index (0.61; P < .001). Impingement area at 20° of extension (ER, 0°) was significantly larger for patients with McKibbin index >70° versus <70° (251 vs 44 mm²; P = .001).

Conclusion

The limited hip extension found in our study could theoretically affect the performance of sports activities such as running, ballet dancing, or lunges. Therefore, although not examined directly in this study, these activities are not advisable for these patients. Preoperative evaluation of FV and the McKibbin index is important in female patients with posterior hip pain before hip preservation surgery (eg, hip arthroscopy).

Acetabular deficiency in borderline hip dysplasia is underestimated by lateral center edge angle alone

INTRODUCTION

In hip preservation surgery, the term "borderline hip dysplasia" was used when the lateral center edge angle (LCEA), historically described by Wiberg, measured 18-25°. In recent years, several radiographic parameters have been described to assess the antero posterior coverage of the femoral head, for example, the anterior and posterior wall index (AWI and PWI). This allowed an increasingly comprehensive understanding of acetabular morphology and a questioning of the borderline definition.

MATERIAL AND METHODS

A retrospective review of 397 consecutive hips was performed, all treated with triple pelvic osteotomy (TPO) due to symptomatic hip dysplasia. On all preoperative pelvic radiographs with a LCEA of 18-25°, acetabular index (AI), AWI and PWI were measured. With these values, the hips were categorized into laterally, antero-laterally and postero-laterally dysplastic and stratified by gender. Intra- and interobserver correlation of the parameters was analyzed by intraclass correlation coefficient (ICC).

RESULTS

According to LCEA, 192 hips were identified as "borderline dysplastic". Based on AWI and PWI, the categorization resulted in 116 laterally dysplastic (60.4%), 33 antero-laterally (17.2%) and 43 postero-laterally dysplastic hips (22.4%). Gender stratification revealed that male acetabula seemed to be slightly more postero-laterally deficient than female (mean PWI 0.80 vs 0.89; p = 0.017). ICC confirmed highly accurate and reproducible readings of all parameters.

CONCLUSION

The rather high proportion of symptomatic hips labelled borderline dysplastic suggested, that there might be substantial acetabular deficiency not recognizable by LCEA. Comprehensive deformity analysis using LCEA, AI, AWI and PWI showed, that 40% of these hips were deficient either antero-laterally or postero-laterally. Male acetabula were more deficient postero-laterally than female.

Hip Pain and Movement Dysfunction Associated With Nonarthritic Hip Joint Pain: A Revision

The Academy of Orthopaedic Physical Therapy (AOPT), formerly the Orthopaedic Section of the American Physical Therapy Association (APTA), has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability, and Health (ICF). This is an update to the 2014 Clinical Practice Guideline (CPG) for Hip Pain and Movement Dysfunction Associated with Nonarthritic Hip Joint Pain. The goals of the revision were to provide a concise summary of the contemporary evidence since publication of the original guideline and to develop new recommendations or revise previously published recommendations to support evidence-based practice. This current CPG covers pathoanatomical features, clinical course, prognosis, diagnosis, examination, and physical therapy interventions in the management of nonarthritic hip joint pain. J Orthop Sports Phys Ther 2023;53(7):CPG1-CPG70. doi:10.2519/jospt.2023.0302.

Can we determine anterior hip coverage from pelvic anteroposterior radiographs? A study of patients with hip dysplasia

PURPOSE

Insufficient coverage causes hip joint instability and results in hip pain. Anterior hip coverage can be determined on both pelvic anteroposterior (AP) radiographs and false profile (FP) radiographs. Four parameters are commonly used to determine the anterior coverage on pelvic AP radiographs: the crossover index, crossover sign, anterior wall index (AWI), and rule of thirds. This study aims to clarify the relationship between these 4 parameters on AP radiographs and the anterior center edge angle (ACEA) on FP radiographs.

METHODS

In this study, 53 patients who underwent periacetabular osteotomy for hip dysplasia at our center between July 2020 and October 2020 were retrospectively reviewed. Four parameters on AP radiographs and the ACEA on FP radiographs before surgery and 6 months after surgery were measured and compared for each hip.

RESULTS

Upon examining the 53 hips in this study, there was no correlation between either the crossover index and the ACEA (P = 0.66) or the crossover sign before surgery. The postoperative correlation between the crossover index and the ACEA was weak (r = 0.36, P = 0.007), and that between the crossover sign and the ACEA was moderate (r = 0.41, P = 0.003). There was a weak correlation between the AWI and ACEA both before (r = 0.288, P = 0.036) and after (r = 0.349, P = 0.011) the operation. Evaluation of the anterior coverage by the rule of thirds was also not consistent when determining the anterior coverage with the ACEA.

CONCLUSION

Anterior coverage on AP radiographs is largely inconsistent with ACEA on FP radiographs, especially before the surgery. It is recommended to take FP radiographs routinely for determining anterior hip coverage.

The natural history of acetabular dysplasia and later total hip arthroplasty in late-detected DDH: 48 patients with closed reduction followed to a mean age of 62 years

BACKGROUND AND PURPOSE

The long-term prognosis of acetabular dysplasia without subluxation in developmental dislocation of the hip (DDH) is uncertain. The aim of this study was to assess the consequence of having acetabular dysplasia at skeletal maturity on the need for having a total hip arthroplasty (THA) up to the age of 60 years.

PATIENTS AND METHODS

Inclusion criteria were age at diagnosis 0.5-3.0 years, initial treatment with skin traction to obtain closed reduction during 1958-1962, and no acetabular procedures to improve femoral head coverage. 48 patients (57 hips) met these criteria, 41 girls and 7 boys. Hip dysplasia was defined as a center-edge (CE) angle at skeletal maturity of 10-19°, and hips with CE angles in the range 20-25° were termed borderline dysplastic.

RESULTS

At skeletal maturity, 18 hips had acetabular dysplasia with a mean CE angle of 15.8° (10-19), whereas 19 hips were borderline with CE angles 20-25°, and 20 hips were normal (CE angles ≥ 26°). During the follow-up period 16 hips had undergone THA, 11 of 18 hips with dysplasia, 4 of 19 with borderline dysplasia, and 1 of 20 hips without dysplasia (p < 0.001). Hip survival in the 18 dysplastic hips, with THA as the endpoint, was 100% up to patient age 40 years; thereafter survival fell to 83% at 50 years and 39% at 60 years. There was no significant correlation between CE angle at skeletal maturity and age at THA (p = 0.2). The mean age at the last follow-up in patients without THA was 62 years (60-64).

CONCLUSION

Acetabular dysplasia without subluxation was a risk factor for THA, but less than one-fifth of the hips had undergone THA up to patient age 50 years.

Standard radiographic values for the acetabulum in Japanese adolescents: a cross-sectional study

BACKGROUND

Most previous reports of normal acetabular radiographic values focused on adults or elderly people. Recent reports have described premature hip osteoarthritis in adolescents not caused by acetabular dysplasia. In addition, there is a certain failure rate of surgical treatment for young patients with borderline acetabular dysplasia. Accurate indices for treatment of adolescent hips are unclear because standard measurement values of the adolescent acetabulum have not been reported.

METHODS

This cross-sectional study involved 552 Japanese adolescents aged 12-18 years who had scoliosis or suspected scoliosis and asymptomatic hips. All persons underwent plain standing anteroposterior whole-spine radiography, and measurements were obtained using the pelvic part of the radiograph. We excluded persons who were unable to correctly perform measurements because of conditions such as pelvic rotation or lateral inclination and persons in whom closure of the triradiate cartilage or closure of the secondary ossification centers of the acetabulum had not yet occurred. In 1101 hips, we measured the lateral center-edge angle (LCEA), Tönnis angle, Sharp angle, acetabular head index (AHI), lateral subluxation (LS), vertical subluxation (VS), and peak-to-edge distance (PED). We evaluated the correlation coefficient and coefficient of determination between each parameter and age, height, body weight, and body mass index (BMI) and assessed the intra- and inter-rater reliability of each radiographic parameter.

RESULTS

Among all hips, the mean of each parameter was as follows: LCEA, 27.9° ± 4.8°; Tönnis angle, 5.0° ± 3.7°; Sharp angle, 44.1° ± 3.1°; AHI, 82.1% ± 5.5%; LS, 5.4 ± 1.4 mm; VS, 0.3 ± 1.2 mm; and PED, 14.0 ± 2.3 mm. The correlation between each parameter and age, height, body weight, and BMI was considerably low. Intra- and inter-rater reliability was moderate or good for almost all parameters.

CONCLUSIONS

The values for each radiographic parameter of the acetabulum in this study are considered standard for the adolescent acetabulum without age-related changes. Some parameters differ slightly from the normal values for adults or elderly people in previous reports; thus, we suggest careful evaluation of these parameters for adolescents.

Dysplastic hips demonstrate increased joint translation at higher body mass index

OBJECTIVE

To determine which radiographic measures used to define the severity of hip dysplasia are associated with hip joint translation and to investigate relationships between position, body mass index, and joint translation.

MATERIALS AND METHODS

This is a cross-sectional retrospective study evaluating 10 validated radiographic measures of dysplasia on weight-bearing AP pelvis and supine 45-degree bilateral Dunn radiographs of 93 young adults with symptomatic hip dysplasia presenting to a single academic institution between October 2016 and May 2019. We determined the difference between standing and supine measurements for each hip and the correlation of each measure with the patient's body mass index.

RESULTS

Femoral head extrusion index was 2.49% lower on supine X-ray (p = 0.0020). Patients with higher body mass index had higher center gap distance (p = 0.0274), femoral head extrusion (p = 0.0170), and femoral head lateralization (p = 0.0028) when standing. They also had higher Tönnis angle (p_standing = 0.0076, p_supine = 0.0121) and lower lateral center-edge angle (p_standing = 0.0196, p_supine = 0.0410) in both positions. The difference in femoral head lateralization between standing and supine positions increased with higher body mass index (p = 0.0081).

CONCLUSION

Translation of the hip joint with position change is demonstrated by decreased femoral head extrusion index on supine X-ray. Patients with higher body mass index had more dysplastic hips, as measured by five of six radiographic outcomes of dysplasia, and experienced more translation with weight-bearing, reflected by increased femoral head lateralization.

The Radiographic Femoroepiphyseal Acetabular Roof Index Is a Reliable and Reproducible Diagnostic Tool in Patients Undergoing Hip-Preservation Surgery: A Systematic Review

PURPOSE

To assess the utility of the femoroepiphyseal acetabular roof (FEAR) index as a diagnostic tool in hip-preservation surgery.

METHODS

MEDLINE, EMBASE, and PubMed were searched from database inception until May 2022 for literature addressing the utility of the FEAR index in patients undergoing hip-preservation surgery, and the results are presented descriptively.

RESULTS

Overall, there were a total of 11 studies comprising 1,458 patients included in this review. The intraobserver agreement for the FEAR index was reported by 3 of 11 studies (intraclass correlation coefficient range = 0.86-0.99), whereas the interobserver agreement was reported by 8 of 11 studies (intraclass correlation coefficient range = 0.776-1). Among the 5 studies that differentiated between hip instability and hip impingement, the mean FEAR index in 319 patients in the instability group ranged from 3.01 to 13.3°, whereas the mean FEAR index in 239 patients in the impingement group ranged from -10 to -0.77° and the mean FEAR index in 105 patients in the control group ranged from -13 to -7.7°. Three studies defined a specific cutoff value for the FEAR index, with 1 study defining a cutoff value of 5°, which correctly predicted treatment decision between periacetabular osteotomy versus osteochondroplasty 79% of the time with an AUC of 0.89, whereas another defined a cutoff of 2°, which correctly predicted treatment 90% of the time and the last study set a threshold of 3°, which provided an AUC of 0.86 for correctly predicting treatment decision.

CONCLUSIONS

This review demonstrates that the FEAR index has a high agreement and consistent application, making it a useful diagnostic tool in hip-preservation surgery particularly in patients with borderline dysplastic hips. However, given the variability in FEAR index cutoff values across studies, there is no absolute consensus value that dictates treatment decision.

LEVEL OF EVIDENCE

Level IV; Systematic Review of Level II-IV studies.

Editorial Commentary: Evaluate for the Beighton Score and Additional Radiographic Signs of Instability Prior to Proceeding With Hip Arthroscopy in Patients With Combined Borderline Hip Dysplasia and Excessive Femoral Anteversion

Femoral version abnormalities have been increasingly recognized as a key factor in the pathogenesis of nonarthritic hip pain. Excessive femoral anteversion (EFA), defined as femoral anteversion greater than 20°, has been postulated to create unstable alignment of the hip, which is exacerbated in patients with concomitant borderline hip dysplasia (BHD). The optimal treatment algorithm for hip pain in EFA-BHD patients remains debated, with some surgeons advocating against arthroscopic procedures in isolation owing to the combined instability due to the femoral and acetabular abnormalities. When determining the treatment approach for an EFA-BHD patient, clinicians should discern whether the patient is presenting with symptoms due to femoroacetabular impingement versus hip instability. When addressing symptomatic hip instability, clinicians are encouraged to evaluate for the Beighton score and additional radiographic factors (other than the lateral center-edge angle) suggestive of instability, such as a Tönnis angle greater than 10°, coxa valga, and deficient anterior or posterior acetabular wall coverage. Because the combination of these additional instability findings with EFA-BHD may portend an inferior outcome after arthroscopic treatment in isolation, an open procedure such as periacetabular osteotomy can be a more reliable treatment option for symptomatic hip instability in this cohort.

Combined Borderline Acetabular Dysplasia and Increased Femoral Anteversion Is Associated With Worse Outcomes in Female Patients Undergoing Hip Arthroscopy for Femoroacetabular Impingement

PURPOSE

To determine the relationship of increased femoral anteversion and borderline acetabular dysplasia on the outcomes of hip arthroscopy for femoroacetabular impingement in a female cohort of patients.

METHODS

This is a retrospective study of female patients undergoing hip arthroscopy for femoroacetabular impingement. All patients had preoperative radiographs and computed tomography scans from which lateral center edge angle (LCEA) and femoral anteversion were measured. Patient outcome was quantified by preoperative and postoperative International Hip Outcome Tool 12-item instrument (iHOT-12). All patients had follow-up at 2 to 4 years postoperatively. Published values for minimum clinically important difference, substantial clinical benefit (SCB), patient acceptable symptomatic state (PASS), and a normal or abnormal hip were used to determine outcome as well as the final score and delta of the iHOT-12.

RESULTS

There were 243 female patients included in the cohort (83% follow-up) who had iHOT-12 scores at 2- to 4-year follow-up (mean 36.9 months). Female patients with combined LCEA ≤25° and femoral anteversion >20° had lower final IHOT-12 scores (P = .001) and delta iHOT-12 (P = .010) and were less likely to achieve a normal hip (P = .013), minimum clinically important difference (P = .018), SCB (P < .001), or PASS (P < .001) and more likely to have an abnormal hip (P = .002). In addition, patients with an LCEA ≤25° and normal femoral version were less likely to achieve a normal hip (P = .013), SCB (P < .001), and PASS (P < .001) compared with those with normal acetabular coverage (all P < .05). There was no difference in these outcome measures between the groups with an LCEA >25° with or without increased femoral version.

CONCLUSIONS

Female patients with femoral anteversion >20° and borderline acetabular dysplasia did poorly after hip arthroscopy. However, those with increased femoral anteversion and normal acetabular coverage had outcomes similar to control hips.

LEVEL OF EVIDENCE

Level IV, case series.

[Preoperative MR imaging for hip dysplasia : Assessment of associated deformities and intraarticular pathologies]

BACKGROUND

Developmental dysplasia of the hip (DDH) is a known reason for hip pain for adolescents and young adults. Preoperative imaging is increasingly recognized as an important factor due to the recent advances in MR imaging.

OBJECTIVES

The aim of this article is to give an overview of preoperative imaging for DDH. The acetabular version and morphology, associated femoral deformities (cam deformity, valgus and femoral antetorsion) and intraarticular pathologies (labrum and cartilage damage) and cartilage mapping are described.

METHODS

After an initial evaluation with AP radiographs, CT or MRI represent the methods of choice for the preoperative evaluation of the acetabular morphology and cam deformity, and for the measurement of femoral torsion. Different measurement techniques and normal values should be considered, especially for patients with increased femoral antetorsion because this could lead to misinterpretation and misdiagnosis. MRI allows analysis of labrum hypertrophy and subtle signs for hip instability. 3D MRI for cartilage mapping allows quantification of biochemical cartilage degeneration and yields great potential for surgical decision-making. 3D-CT and, increasingly, 3D MRI of the hip to generate 3D pelvic bone models and subsequent 3D impingement simulation can help to detect posterior extraarticular ischiofemoral impingement.

RESULTS AND DISCUSSION

Acetabular morphology can be divided in anterior, lateral and posterior hip dysplasia. Combined osseous deformities are common, such as hip dysplasia combined with cam deformity (86%). Valgus deformities were reported in 44%. Combined hip dysplasia and increased femoral antetorsion can occur in 52%. Posterior extraarticular ischiofemoral impingement between the lesser trochanter and the ischial tuberosity can occur in patients with increased femoral antetorsion. Typically, labrum damage and hypertrophy, cartilage damage, subchondral cysts can occur in hip dysplasia. Hypertrophy of the muscle iliocapsularis is a sign for hip instability. Acetabular morphology and femoral deformities (cam deformity and femoral anteversion) should be evaluated before surgical therapy for patients with hip dysplasia, considering the different measurement techniques and normal values of femoral antetorsion.

Limited External Rotation and Hip Extension Due to Posterior Extra-articular Ischiofemoral Hip Impingement in Female Patients With Increased Femoral Anteversion: Implications for Sports, Sexual, and Daily Activities

BACKGROUND

Posterior femoroacetabular impingement (FAI) is poorly understood. Patients with increased femoral anteversion (FV) exhibit posterior hip pain.

PURPOSE

To correlate hip impingement area with FV and with combined version and to investigate frequency of limited external rotation (ER) and hip extension (<40°, <20°, and <0°) due to posterior extra-articular ischiofemoral impingement.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Osseous patient-specific three-dimensional (3D) models based on 3D computed tomography scans were generated of 37 female patients (50 hips) with positive posterior impingement test (100%) and increased FV >35° (Murphy method). Surgery was performed in 50% of patients (mean age, 30 years; 100% female). FV and acetabular version (AV) were added to calculate combined version. Subgroups of patients (24 hips) with increased combined version >70° and patients (9 valgus hips) with increased combined version >50° were analyzed. The control group (20 hips) had normal FV, normal AV, and no valgus. Bone segmentation was performed to generate 3D models of every patient. Validated 3D collision detection software was used for simulation of impingement-free hip motion (equidistant method). Impingement area was evaluated in combined 20° of ER and 20° of extension.

RESULTS

Posterior extra-articular ischiofemoral impingement occurred between the ischium and the lesser trochanter in 92% of patients with FV >35° in combined 20° of ER and 20° of extension. Impingement area in combined 20° of ER and 20° of extension was larger with increasing FV and with higher combined version; correlation was significant (P < .001, r = 0.57, and r = 0.65). Impingement area was significantly (P = .001) larger (681 vs 296 mm2) for patients with combined version >70° (vs <70°, respectively) in combined 20° of ER and 20° of extension. All symptomatic patients with increased FV >35° (100%) had limited ER <40°, and most (88%) had limited extension <40°. The frequency of posterior intra- and extra-articular hip impingement of symptomatic patients (100% and 88%, respectively) was significantly (P < .001) higher compared with the control group (10% and 10%, respectively). The frequency of patients with increased FV >35° with limited extension <20° (70%) and patients with limited ER <20° (54%) was significantly (P < .001) higher compared with the control group (0% and 0%, respectively). The frequency of completely limited extension <0° (no extension) and ER <0° (no ER in extension) was significantly (P < .001) higher for valgus hips (44%) with combined version >50° compared with patients with FV >35° (0%).

CONCLUSION

All patients with increased FV >35° had limited ER <40°, and most of them had limited extension <20° due to posterior intra- or extra-articular hip impingement. This is important for patient counselling, for physical therapy, and for planning of hip-preservation surgery (eg, hip arthroscopy). This finding has implications and could limit daily activities (long-stride walking), sexual activity, ballet dancing, and sports (eg, yoga or skiing), although not studied directly. Good correlation between impingement area and combined version supports evaluation of combined version in female patients with positive posterior impingement test or posterior hip pain.

High-Level Athletes With Borderline Hip Dysplasia Achieve Favorable Outcomes and Return to Sport Rates Following Primary Hip Arthroscopy: Minimum 5-Year Outcomes Comparison to a Propensity-Matched Control Group

PURPOSE

(1) To report minimum 5-year patient-reported outcomes (PROs) and return to sport (RTS) rates in high-level athletes with borderline hip dysplasia (BHD) following primary hip arthroscopy for labral pathology and femoroacetabular impingement syndrome and (2) to compare results to a propensity-matched control group of athletes with normal acetabular coverage.

METHODS

Data were reviewed for surgeries performed between February 2009 and February 2016. Patients were eligible if they underwent primary hip arthroscopy in the setting of BHD (lateral center-edge angle [LCEA] 18-25°) and competed in professional, collegiate, or high school sports. Inclusion criteria were preoperative and minimum 5-year follow-up scores for the modified Harris Hip Score (mHHS), Non-Arthritis Hip Score, Hip Outcome Score-Sport Specific Subscale (HOS-SSS), and visual analog scale for pain. Rates of achieving the minimal clinically importance difference (MCID), patient acceptable symptomatic state (PASS), and maximum outcome improvement satisfaction threshold (MOIST) were recorded in addition to RTS. BHD athletes were matched by age at the time of surgery, sex, body mass index, Tönnis grade, follow-up time, sport type, and competition level to a control group of 58 athletes with normal acetabular coverage (LCEA 25°-40°) for comparison.

RESULTS

A total of 34 BHD athletes were included with a mean follow-up of 73.6 ± 10.7 months. BHD athletes showed significant improvements in all PROs, demonstrated high RTS rates (90.0%), and achieved PASS/MCID/MOIST for mHHS (MCID: 80.0%, PASS: 93.3%, MOIST: 80.0%) and HOS-SSS (MCID: 76.7%, PASS: 73.3%) at high rates. When compared to a propensity-matched group with normal acetabular coverage, BHD athletes demonstrated similar postoperative PROs, rates of achieving psychometric thresholds, and RTS rates (P > .05). Additionally, by the latest follow-up, no athlete in either group required conversion to total hip arthroplasty.

CONCLUSIONS

High-level athletes with BHD undergoing primary hip arthroscopy for labral pathology and femoroacetabular impingement syndrome may expect favorable midterm outcomes and high RTS rates. These results were comparable to a control group of athletes with normal coverage.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

The anterior hip capsule is thinner in dysplastic hips: a study comparing different young adult hip patients

PURPOSE

To investigate the thickness and intra-substance change of anterior capsule of the hip joint, and compare the difference of the capsular features in patients with different statuses of hip stability.

METHODS

A retrospective study was performed to review a hip preservation database. Using the lateral center edge angle(LCEA), patients with borderline dysplasia of the hip (BDH) of 20° ≤ LCEA ≤ 25°, femoracetabular impingement(FAI) with LCEA > 30° and dysplasia of the hip (DH) of LCEA < 20° were enrolled and stratified into different treatment groups. The patients' imaging was reviewed by two experienced musculoskeletal radiologists who were blinded to clinical outcomes. Thickness and intra-substance change of the anterior hip capsule was measured on the sagittal oblique sequences of MRI. A surgeon measured the thickness of the anterior hip capsule during arthroscopy. The capsular thickness and intra-substance change were compared among different groups.

RESULTS

Thirty patients (17 women and 13 men) enrolled in each group (FAI, BDH, and DH) matched by sex and ages were evaluated. There were no significant differences in terms of age, sex, BMI, Alpha angle, and Tönnis grade among all three groups. The mean thickness of the anterior capsule in the DH group was 3.2 ± 0.5 mm, which was significantly thinner than that in the BDH and FAI groups (4.5 ± 0.8 mm and 4.7 ± 0.6 mm), and there was no significant difference in capsular thickness between the BDH and FAI groups. The Median of anterior capsule thickness via arthroscopic measuring was 6 mm and 7 mm in the BDH and FAI groups respectively, which has no statistical difference. The intra-substance change of the anterior capsule shows a significant difference among the three groups, and a higher incidence of delamination of the capsule was found in DH groups (p < 0.001).

CONCLUSIONS

Patients with hip dysplasia have a significantly reduced capsular thickness on MRI and delaminated anterior joint capsule, which could be a sequence of instability. The clinical relevance of this study is that capsular thickness and intra-substance changes of the anterior capsule vary which could alter capsular management strategies.

LEVEL OF EVIDENCE

Level III of evidence, DIAGNOSTIC STUDIES, No consistently applied reference standard.

Association of Cam Deformity on Anteroposterior Pelvic Radiographs and More Severe Chondral Damage in Femoroacetabular Impingement Syndrome

BACKGROUND

Abnormal proximal femoral morphology in femoroacetabular impingement syndrome (FAIS) identifiable on the anteroposterior (AP) pelvic radiograph has been described as the "pistol grip" deformity. The effect of a superior cam deformity identified on this radiographic view remains unknown.

PURPOSES

To assess the relationship between AP cam deformity (AP alpha angle [AP AA] >55°) and cartilage injury; to assess the relationship between AP cam deformity and labral injury; and to determine if patient factors are correlated with cartilage and labral injury.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Patients undergoing osteochondroplasty and labral repair for FAIS with a single surgeon were identified retrospectively. Intraoperative size, location, and severity of cartilage and labral damage were prospectively collected. Chondrolabral and femoral/acetabular cartilage damage were graded with the Beck labral and cartilage injury criteria. Radiographic data included the AP AA, lateral center-edge angle (LCEA), and maximum femoral alpha angle (MF AA). Patients with hip dysplasia (LCEA <18°; LCEA 18°-25° with acetabular index >10°) were excluded. Outcomes were compared across cartilage and labral severity grades. We report odds ratios (ORs) with 95% confidence intervals and P values from multivariable logistic regressions.

RESULTS

Of the 158 included hips (154 patients), 69% were female and the mean (± standard deviation [SD]) age was 30.3 ± 9.7 years. Increase in age, increase in body mass index (BMI), and male sex were associated with increasing severity of cartilage and labral injury. More severe cartilage damage was associated with increasing AP AA (P < .001) and MF AA (P < .001). The odds of developing a higher category of cartilage injury severity (grade ≥3) were 119% higher (OR, 2.19 [95% CI, 1.36-3.64]; P = .002) for every SD increase (16.7°) in AP AA, adjusting for age, sex, and BMI. The odds of developing a severe labral injury (grade ≥3) were 118% higher (OR, 2.18 [95% CI 1.17-4.32]; P = .018) for every SD increase (10.5°) in MF AA, adjusting for age, sex, BMI, and AP AA.

CONCLUSION

Increasing age and BMI, and male sex are associated with increasing severity of cartilage and labral injury in FAIS. The odds of developing a cartilage injury are significantly higher with independent increases in AP AA and MF AA.

Generalized Joint Laxity Is Associated With Dynamic Hip Ultrasonography Measures in Female Athlete Patients Who Are Not Hypermobile

OBJECTIVES

To investigate ultrasound (US) femoroacetabular translation measurements in female athlete patients.

METHODS

A prospective cross-sectional study was conducted in female athlete patients <50 years. Demographic data, Beighton score/hypermobility status, and sport participation were collected. Hip dysplasia was determined using radiographic measurements (lateral center edge angle, anterior center edge angle, Tönnis angle); femoral version angles were measured with CT or MR. Femoroacetabular translation US measures included neutral (N), neutral flexed (NF), extension external rotation/apprehension (EER) positions. Maximal difference (delta) between US measures was calculated.

RESULTS

206/349 female hips were analyzed (median age 21.2 years [range, 12-49.5]). The primary sport group was performing arts (45%, 92/206). Mean Beighton score was 5.2 (SD, 2.5) with 61% (129/206) of hips exhibiting hypermobility (Beighton score ≥5). For each additional unit of Beighton score, N US measurement increased by 0.7 mm (β = 0.7; 95% confidence interval [CI] = 0.22-1.25; P < .001), NF by 1 mm ( β = 0.9; 95% CI = 0.3-1.43; P = .002) and EER by 0.8 mm ( β = 0.8; 95% CI = 0.27-1.37; P < .001) when adjusting for age and dysplasia status. A positive correlation was detected between NF (r = 0.19; 95% CI = 0.05-0.33; P = .007) and EER (r = 0.19; 95% CI = 0.05-0.32; P = .01) with Tönnis angle and a negative correlation between the delta and femoral version (r = -0.20; 95% CI = -0.35 to 0.03; P = .02). No difference in US measures was detected across sport groups (N [P = .24], NF [P = .51], EER [P = .20], delta [P = .07]).

CONCLUSION

Beighton score was independently associated with dynamic US measures in female athlete patients who are not hypermobile when controlling for other factors.

Intraoperative Fluoroscopy Allows the Reliable Assessment of Deformity Correction during Periacetabular Osteotomy

We aimed to determine the accuracy and reliability of measures characterizing anterior, lateral, and posterior acetabular coverage on intraoperative fluoroscopic images compared to postoperative radiographs when performing periacetabular osteotomies (PAOs). A study involving 100 PAOs was initiated applying a standardized intraoperative imaging protocol. Coverage was determined by the lateral center edge angle (LCEA), the Tönnis angle (TA), and the anterior and posterior wall index (AWI, PWI). An intraclass correlation coefficient (ICC) model was used to assess interrater (ICC (3,2)) and intrarater (ICC (2,1)) reliability. The ICC (2,2) between analyses obtained from intraoperative fluoroscopy and postoperative radiographs and the corresponding 95% confidence interval (CI) were determined and complemented by Bland–Altman analysis, the mean difference, and 95% limits of agreement (LOA). The ICCs were 0.849 for the LCEA (95% CI 0.783–0.896), 0.897 for the TA (95% CI 0.851–0.930), 0.864 for the AWI (95% CI 0.804–0.907), and 0.804 for the PWI (0.722–0.864). The assessed interrater reliability was excellent except for the AWI, which was graded good (ICC = 0.857, 95% CI 0.794–0.902). Interrater agreement was generally good and fair for the AWI (ICC = 0.715, 95% CI 0.603–0.780). For each postoperative radiograph, interrater reliability was good with ICCs ranging from 0.813 (TA) to 0.881 (PWI). Intrarater reliability was good for all measurements and excellent for the preoperative TA (ICC = 0.993, 95% CI 0.984–0.997) and PWI (ICC = 0.954, 95% CI 0.919–0.97). In summary, we confirm the validity and reliability of intraoperative fluoroscopy as an alternative imaging modality to radiography to evaluate acetabular fragment orientation during PAO. We affirm the LCEA and TA as precise measures for lateral head coverage, and show the suitability of the AWI and PWI to steadily assess acetabular version.

Females and Males Achieved Comparable Outcomes and Clinical Benefits Following Primary Hip Arthroscopy with Labral Repair, but Age Affected Outcomes and Conversion to Total Hip Arthroplasty. A Short and Mid-Term Follow-Up Analysis with Dual Stratification

PURPOSE

To report and compare, according to sex and age, minimum 2-and minimum 5-year patient-reported outcome scores (PROs) and survivorship in a large cohort of patients who underwent primary hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

METHODS

Data from February 2008 to September 2018 were reviewed. Patients aged 60 and younger who underwent primary hip arthroscopy with minimum 2-year follow-up were included. Exclusion criteria were Tönnis grade >1, hip dysplasia, previous hip conditions, or any labral treatment different than repair. Minimum 5-year PROs were also collected. All patients included were divided into groups by sex. For further analysis, males and females were stratified according to age: < 21 years old, 21-30 years old, 31-40 years old, 41-50 years old, and 51-60 years old.

RESULTS

In total, 1,326 hips had minimum 2-year follow-up, including 860 (64.9%) females and 466 males (35.1%), with a mean age of 31.6 years (range, 12.8-60.9 years) and a mean follow-up of 58.7 ± 28.9 months. Of those, 772 had minimum 5-year follow-up, 515 females (66.7%), and 257 males (33.3%) with a mean age of 31.7 years (range, 13.1-60.7 years) and a mean follow-up of 78.5 ± 23.0 months. All patients showed significant improvements in PROs at minimum 2-and 5-year follow-up (P < .001). Between sex analysis revealed comparable PROs at latest follow-up between females and males across any age group. Within sexes, and when sexes were combined, patients <21 years old had significantly better outcomes compared to other age groups. There were more females <21 years old that required revision arthroscopy than males <21 years old (P = .015). Conversion to total hip arthroplasty (THA) showed no significant difference between sexes (P > .05). Rates of THA were <21 years (.8%), 21-30 years (2.1%), 31-40 years (4%), 41-50 years (8.9%), and 51-60 years (14.3%).

CONCLUSIONS

Following primary hip arthroscopy for FAIS, all patients reported significant improvements in all PROs at minimum 2-and minimum 5-year follow-up, with females and males achieving similar success. Age affected outcomes, with patients under 21 years old reporting better scores regardless of sex. Although the conversion rate to THA was similar between the sexes, it was lower in the younger ages groups in both sexes.

LEVEL OF EVIDENCE

III, retrospective comparative observation trial.

External Validation of the FEAR Index in Borderline Acetabular Dysplasia

Background

Given the lack of established, externally validated criteria for the diagnosis of unstable hips, the Femoro-Epiphyseal Acetabular Roof (FEAR) index has been proposed as a useful tool for identifying hips with instability in the setting of borderline acetabular dysplasia.

Purposes

To (1) determine the external performance of the FEAR index in identifying hips with a clinical diagnosis of instability in the setting of borderline dysplasia and (2) assess the performance of the FEAR index compared with acetabular inclination or physeal scar angle alone.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

The authors reviewed 176 patients with borderline acetabular dysplasia (lateral center-edge angle, 20°-25°). A positive FEAR index was defined as ≥5°. An alternative threshold ≥2° was also assessed. Significant instability was determined by the senior surgeon based on the combination of patient and radiographic features; unstable hips were treated with periacetabular osteotomy (with or without hip arthroscopy), and stable hips were treated with isolated hip arthroscopy.

Results

Only 18% of borderline hips had a positive FEAR index. The ≥5° positive FEAR index threshold had a sensitivity of 33% (23/70) and specificity of 92% (98/106) in predicting the clinical diagnosis of instability. The ≥2° FEAR index threshold had a sensitivity of 39% (27/70) and specificity of 89% (94/106) in predicting the clinical diagnosis of instability. No alternative threshold for the FEAR index resulted in high levels of sensitivity and specificity. A threshold of -5° was required to reach an adequate sensitivity of 74%. The FEAR index remained a significant predictor of hip instability even after controlling for acetabular inclination (odds ratio, 1.12; P < .001) or physeal scar angle (odds ratio, 1.6; P < .001).

Conclusion

In the current study, a positive FEAR index was generally indicative of the presence of clinical instability, but the FEAR index alone remained inadequate to fully define the instability of a given hip, as it demonstrated low sensitivity (only 33%) in the external validation. The FEAR index is best used in the context of other clinical and radiographic features.

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

Purpose of Review

This literature review aims to survey the current knowledge about the management FAI in the setting of borderline hip dysplasia.

Recent Findings

With better understanding, hip arthroscopy has recently been advocated for treating mild or borderline hip dysplasia (BDH) with concomitant femoroacetabular impingement (FAI) despite early studies that condemned its use. Recent outcome data have demonstrated that hip arthroscopy is a viable option in BDH, with and without FAI, and has been gaining wider acceptance. Hip arthroscopy can address the concomitant soft tissue and bony intra-articular pathologies and obviate the necessity for other surgeries. Moreover, hip arthroscopy may be used as an adjuvant treatment to other procedures such as a periacetabular osteotomy (PAO).

Summary

Hip arthroscopy for BDH is an evolving procedure with promising short- and mid-term outcomes. The combination of BDH and FAI is becoming recognized as a problem in its own right, requiring dedicated treatment.

Predictive radiological parameters of failure following surgical management of femoroacetabular impingement associated with borderline acetabular dysplasia

INTRODUCTION

The role of arthroscopic treatment of femoroacetabular impingement (FAI) in mild or borderline hip dysplasia (lateral center edge angle=18-25) is controversial. It is recommended to combine capsular plication with femoral neck osteoplasty and suture repair of the labrum. Few studies have investigated which radiological parameters are associated with failure of this procedure.

HYPOTHESIS

A larger number of radiological signs of mild or borderline hip dysplasia than radiological signs of FAI negatively influence the outcomes of arthroscopic treatment.

METHODS

This was a retrospective study done with data collected prospectively after a minimum of 2 years' follow-up in patients who underwent arthroscopic treatment of FAI due to cam impingement combined with mild to moderate hip dysplasia. Patients with hip osteoarthritis graded as ≥ Tönnis 2 were excluded. Functional outcome scores (mHHS and NAHS) were determined along with the need for reoperation. Three groups were defined based on the outcomes: success (mHHS ≥ Patient Acceptable Symptomatic State [PASS]); moderate improvement (improvement in mHHS + mHHS<PASS) and failure (worsening of the mHHS). Demographic data, radiographic parameters (LCEA, Tönnis angle, alpha angle, offset, FEAR index, Shenton's line, Cliff sign, anterior wall index [AWI], posterior wall index [PWI]) and intraoperative findings were compared between these three groups. The area under the curve (AUC) for the most relevant data identified during the univariate analysis were then modeled to define which factors were the best at predicting failed arthroscopic treatment a posteriori.

RESULTS

The study analyzed 39 patients. The mean mHHS was 76±15 [40-92]. The "success" group consisted of 21 patients (56%, 21/39), the "moderate improvement" group of 12 patients (31%, 12/39) and the failure group of 6 patients (13%, 6/39) (2 subsequently underwent total hip replacement, 4 underwent shelf acetabuloplasty). The FEAR index was significantly higher and the AWI and VCE were significantly lower in the "failure" group. The FEAR index was the best predictive factor; an index ≥ 4° detected 100% of failures with 96% specificity. The patients in the "moderate improvement" group were significantly older (37 years±8 [18-45]<p= 0.04) with a significantly higher offset (2mm±3 [-5-5]<p=0.004); an offset ≥ 2mm could detect 73% of them with a specificity of 72%.

CONCLUSION

A FEAR index ≥ 4° and offset ≥ 2mm is best able to detect patients at risk of failure and unsatisfactory results, respectively, in the mild clinical cam-type impingement in a population of FAI patients.

LEVEL OF EVIDENCE

IV, retrospective series.

Does Femoral Head Translation Vary by Sex and Side in Asymptomatic Hips During a Weightbearing Apprehension Test?

BACKGROUND

Hip microinstability is an increasingly recognized source of pain and dysfunction but has no agreed upon diagnostic criteria and the pathophysiology remains unclear. It has been suggested that pain associated with microinstability is caused by excess translation of the femoral head. Recent research indicates that single-plane femoral head translation can be reliably measured using dynamic ultrasonography during a supine clinical examination; however, the overall accuracy of that technique has not been established, and the range of femoral head translation values that are found in individuals with no history of surgery or symptomatic pathology is unknown.

QUESTIONS/PURPOSES

(1) How much femoral head translation is present in native, uninjured hips during a weightbearing apprehension position for females and males? (2) How large is the side-to-side difference in hip translation and rotation within the same individual in females and males with no history of surgery or pain during the weightbearing apprehension position? (3) What differences exist in femoral head translation and rotation when comparing females to males?

METHODS

Twenty-two young adults (11 males, 11 females; mean age 22 ± 2 years; BMI 22 ± 5 kg/m2) with no history of hip pain, no known hip injury, and who never had hip surgery participated in this study. High-resolution CT images of the femur and pelvis were acquired for each participant, and the bone tissue was segmented from the CT volume. Synchronized biplane radiographs were collected during a neutral standing trial and during a static weightbearing apprehension position in which the participant extended, externally rotated, and abducted at their back hip while standing with their feet split in the AP direction. A validated volumetric model-based tracking technique was used to match the patient-specific bone models to the biplane radiographs with an accuracy of 0.3 mm for translation and 0.8° for rotation. Translation of the center of the femoral head relative to the center of the acetabulum and rotation of the femur relative to the pelvis from neutral to the weightbearing apprehension position were calculated. Sex-based differences in hip kinematics were assessed by bivariate linear regression.

RESULTS

The median (range) translation during the weightbearing apprehension position in females was 0.9 mm (0.2 to 2.7 mm), which was less than in the 1.3 mm (0.2 to 2.6 mm) translation found in males (median difference of 0.5 mm; p = 0.04). The median absolute side-to-side difference in translation during the pivot was 1.4 mm (0.1 to 3.8 mm) in females and 1.3 mm (0.1 to 4.4 mm) in males.

CONCLUSION

These findings demonstrate that the femoral head translates the same under bodyweight loading as previously observed during supine exam, showing the inherent stability of the hip with no history of surgery or symptomatic pathology. This study also provides normal values for comparison with individuals who have suspected microinstability. Future directions for research include directly comparing biplane radiography to alternative imaging techniques, such as dynamic ultrasound, for identifying hip microinstability and identifying threshold values for symptomatic hip microinstability.

LEVEL OF EVIDENCE

Level III, prognostic study.

Patients With a High Femoroepiphyseal Roof With Concomitant Borderline Hip Dysplasia and Femoroacetabular Impingement Syndrome Do Not Demonstrate Inferior Outcomes Following Arthroscopic Hip Surgery

PURPOSE

The purpose of this study was to compare outcomes after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) in patients with borderline hip dysplasia and hip instability defined radiographically using the femoroepiphyseal acetabular roof (FEAR) index and in patients without radiographic evidence of hip instability.

METHODS

Data from consecutive patients with borderline hip dysplasia (lateral center edge angle between 18˚-25˚) who underwent primary hip arthroscopy between April 2012 and June 2017 for the treatment of FAIS were analyzed. Baseline demographic data, radiographic parameters, preoperative, and 2-year postoperative patient-reported outcome measures were collected. The FEAR index was measured by 3 different observers. Patients with an average FEAR index ≥2˚ were categorized as having radiographic evidence of instability as previously published. The analysis was powered to detect a minimal clinically important difference (MCID) for each outcome score. Statistical analysis was performed as appropriate to compare patients with FEAR index ≥2 and <2°.

RESULTS

A total of 140 patients met the inclusion criteria. The average age and body mass index of included patients was 31.7 ± 13.2 (P < .325) years and 25.1 ± 5.6 kg/m² (P < .862). There were no statistically significant demographic differences between the groups. Nineteen (13.0%) patients were found to have a FEAR index of over 2˚. The FEAR index <2° and FEAR index ≥2° groups had a mean preoperative FEAR index (standard deviation, range) of -7.0 (5.2, -26.8 to 1.9) and 4.8 (2.5, 2.0-11.8), respectively. The interrater intraclass correlation coefficient was 0.96. Postoperative patient-reported outcomes and rates of MCID and patient-acceptable symptomatic state achievement were not statistically different between the radiographically stable and unstable groups. (p>0.05 for all).

CONCLUSION

Patients with borderline hip dysplasia and radiographic evidence of hip instability, as measured by the FEAR index (≥2°), achieve similar improvement in 2-year outcomes compared to those with radiographically stable hips after arthroscopic treatment of FAIS.

CLINICAL RELEVANCE

Retrospective Level III cohort study.

Increased Combined Anteversion Is an Independent Predictor of Ischiofemoral Impingement in the Setting of Borderline Dysplasia With Coxa Profunda

PURPOSE

To investigate the differences in radiologic parameters between borderline dysplasia hips (BDDH) +/- coxa profunda and normal hips and to evaluate the correlations between these parameters and the prevalence of ischiofemoral impingement (IFI) in borderline dysplasia.

METHODS

The imaging of patients with BDDH (18° ≤ lateral center edge angle <25°) treated in our hospital from January 2018 to December 2019 was retrospective reviewed. These patients were divided into BDDH with coxa profunda (acetabular fossa touches the ilioischial line, pBDDH) and without coxa profunda (nBDDH) groups. The groups were compared with a control group with normal acetabular coverage. Neck-shaft angle, femoral offset, acetabular versions, acetabular coverage, ischial angle, femoral neck version, and combined anteversion were reviewed and analyzed using computed tomography imaging using one-way analysis of variance.

RESULTS

There were 43 patients (36 female/7 male, 26.13 ± 4.96 years) in the pBDDH group, 22 patients (17 female/5 male, 28.60 ± 5.89 years) in the nBDDH group, and 23 patients (14 female/9 male, 27.67 ± 5.98 years) in the control group. The pBDDH group had increased femoral version, ischial angle, acetabular versions, and decreased ischiofemoral space (IFS)/quadratus femoris space (QFS) than the other 2 groups. The IFS/QFS correlated with neck-shaft angle, femoral offset, femoral neck version, acetabular versions, ischial angle, femoral neck-lesser trochanter angle, posterior acetabular coverage, and combined anteversion in patients with BDDH. Combined anteversion at the 3-o'clock level was an independent predictor of a decreased IFS (beta = -0.348, P = .007) and QFS (beta = -0.255, P = .01, R² = .550). Binary logistic regression demonstrated that patients with BDDH with large combined anteversion at the 3-o'clock level had a greater prevalence of IFI (odds ratio 1.148; P = .001, R² = .505).

CONCLUSIONS

In patients with borderline dysplasia, the QFS/IFS significantly correlated with combined anteversion at the 3-o'clock level on clock face of acetabulum. BDDH with coxa profunda might have a greater prevalence of IFI because of large combined anteversion.

LEVEL OF EVIDENCE

III, retrospective comparative observation study.

Association of Radiographic Markers of Hip Instability and Worse Outcomes 2 to 4 Years After Hip Arthroscopy for Femoroacetabular Impingement in Female Patients

BACKGROUND

Reported outcomes of patients undergoing hip arthroscopy for femoroacetabular impingement (FAI) with underlying borderline acetabular dysplasia are mixed. This may in part be the result of mixed-sex reporting.

PURPOSE

To determine the effect of radiographic measures of acetabular dysplasia and hip instability on outcomes of female patients undergoing hip arthroscopy for FAI.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

This was a retrospective study of female patients undergoing arthroscopic surgery for FAI. All patients had preoperative radiographs including a standing anteroposterior pelvic view on which lateral center-edge angle (LCEA), anterior wall index (AWI), posterior wall index (PWI), and femoroepiphyseal acetabular roof (FEAR) index were measured. Patient outcomes were quantified by preoperative and postoperative 12-Item International Hip Outcome Tool (iHOT-12) scores. All patients had follow-up at 2 to 4 years postoperatively. Published values for minimal clinically important difference (MCID), substantial clinical benefit (SCB), Patient Acceptable Symptom State (PASS), and a normal (iHOT-12 > 86 points) or abnormal (iHOT-12 < 56 points) hip were used to determine outcome, as well as the final iHOT-12 score and iHOT-12 preoperative to postoperative difference.

RESULTS

The cohort consisted of 249 female patients (83% follow-up) with iHOT-12 scores at 2 to 4 years after surgery (mean, 34.6 months). Female patients with combined LCEA ≤25° and AWI <0.35 had lower final iHOT-12 score and iHOT-12 difference and were less likely to meet MCID, SCB, and PASS and have a normal hip and were more likely to have an abnormal hip as determined by iHOT-12 cutoffs when compared with those patients who had an LCEA >25° and an AWI ≥0.35 (all P < .05). There was no effect of PWI on outcomes. Similarly, female patients with combined LCEA ≤25° and a laterally oriented (positive) FEAR index were less likely to meet MCID, SCB, and PASS and have a normal hip and were more likely to have an abnormal hip compared with those patients who had an LCEA >25° and a negative (medial) FEAR index (all P < .05). In multivariate regression, an LCEA between 18° and 25° was an independent predictor of worse outcomes.

CONCLUSION

An LCEA of 18° to 25°, in combination with an AWI of <0.35 or a laterally opening FEAR index, was predictive of worse outcomes in female patients undergoing hip arthroscopy for FAI.

Ten-Year Outcomes After Hip Arthroscopy in Patients With Femoroacetabular Impingement and Borderline Dysplasia

BACKGROUND

The role of hip arthroscopy in the treatment of patients with borderline hip dysplasia is controversial and evolving.

PURPOSE

To evaluate outcomes at a minimum 10-year follow-up in patients who underwent hip arthroscopy for femoroacetabular impingement in a hip with borderline dysplasia.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

All hips that underwent labral repair between June 2006 and March 2009 for femoroacetabular impingement with borderline dysplasia were included if they had a lateral center-edge angle of 20° to 25°, had primary hip arthroscopy for the diagnosis of femoroacetabular impingement, and were aged 18 to 70 years. Patients were excluded if they had previous hip surgery, avascular necrosis, or fracture. Kaplan-Meier survivorship was performed, with survivorship defined as avoidance of conversion to total hip arthroplasty (THA).

RESULTS

A total of 45 patients met the inclusion criteria, and 38 were contacted at a minimum 10 years postoperatively (84%; mean ± SD, 12 ± 1.3 years). There were 23 women and 15 men with an average age of 41 ± 9.6 years (range, 25-69). Twenty patients were ≥40 years of age. In this patient cohort, survivorship was 87% at 5 years and 79% at 10 years for conversion to THA. Of the 38 patients included, 9 were converted to THA (24%), and 3 required revision hip arthroscopy (7%). Patient age, Tönnis grade, microfracture of cartilage lesions, and Tönnis angle >15° were associated with conversion to THA. No statistically significant differences were found between those who underwent conversion to THA and those who did not regarding lateral center-edge angle, Sharp angle, or alpha angle. Significant improvements were seen at follow-up of 12 years (range, 10-13) for the modified Harris Hip Score (58 to 83; P = .002), Hip Outcome Score-Activities of Daily Living (70 to 87; P = .003), Hip Outcome Score-Sport (47 to 76; P = .004), and Western Ontario and McMaster Universities Osteoarthritis Index (31 to 10; P = .001). At follow-up, >80% maintained the minimal clinically important difference for the Hip Outcome Score (Activities of Daily Living and Sport) with no differences between patients aged <40 and ≥40 years.

CONCLUSION

Risk factors for conversion to THA after hip arthroscopy in the borderline dysplastic hip included older age, higher Tönnis grades, grade 4 chondral lesions that were microfractures, and Tönnis angle >15°. In those patients who did not convert to THA, improvement in outcome measures was seen at 10 years. Careful patient selection is critical to the success of this procedure.

Adding false-profile radiographs improves detection of developmental dysplasia of the hip, data from the CHECK cohort

The aim of this study was to determine the additional value of the false-profile (FP) view radiograph in the diagnosis of developmental dysplasia of the hip (DDH), as compared with an anteroposterior (AP) pelvic radiograph only, and evaluate the correlation between the Wiberg-lateral center edge angle (W-LCEA) and Wiberg-anterior center edge angle (W-ACEA). We used baseline data from a nationwide prospective cohort study (Cohort Hip and Cohort Knee). DDH was quantified on AP pelvic and FP hip radiographs using semi-automatic measurements of the W-LCEA and W-ACEA. A threshold of <20° was used to determine DDH for both the W-LCEA and the W-ACEA. The proportion of DDH only present on the FP view determined the FP view additional value. The correlation between the W-LCEA and W-ACEA was determined. In total 720 participants (1391 hips) were included. DDH was present in 74 hips (5.3%), of which 32 were only present on the FP view radiograph (43.2%). The Pearson correlation coefficient between W-LCEA and W-ACEA of all included hips was 0.547 (95% confidence interval: 0.503–0.591) and 0.441 (95% confidence interval: 0.231–0.652) in hips with DDH. A mean difference of 9.4° (SD 8.09) was present between the W-LCEA and the W-ACEA in the hips with DDH. There is a strong additional value of the FP radiograph in the diagnosis of DDH. Over 4 out of 10 (43.2%) individuals’ DDH will be missed when only using the AP radiograph. In hips with DDH a moderate correlation between W-LCEA and W-ACEA was calculated indicating that joints with normal acetabular coverage on the AP view can still be undercovered on the FP view.

Editorial Commentary: Hip Dysplasia-Arthroscopic Femoroacetabular Impingement Versus Periacetabular Osteotomy: Do Not FEAR the Size of the Next Step

Hip dysplasia is characterized by inadequate acetabular coverage of the femoral head. There is a consensus that hip dysplasia with a lateral center edge angle (LCEA) less than18° should be treated with realignment of acetabular coverage by acetabular osteotomy, but there is controversy whether milder, borderline dysplasia with an LCEA between 18° and 25° should be treated with arthroscopy or acetabular reorientation. Identifying whether the problem is related to dysplasia or femoroacetabular impingement syndrome is essential, and a crucial factor is whether the hip is unstable. A femoroepiphyseal acetabular roof (FEAR) index with a cutoff value of 2 predicts hip stability with 90% probability, even with a normative LCEA. In addition, according to the anterior-wall index (AWI), the anterior acetabular border should cross onto the middle third of the medial femoral head radius on a line that runs parallel to the femoral neck axis through the center of the femoral head. A reduced AWI suggests a deficient anterior rim. Next, lateral labrum length correlates with the FEAR index and anterior labrum length with AWI, i.e., anterior dysplasia. Consequently, the lateral labrum increases in size with progressive instability, and the anterior labrum increases in size with decreased anterior coverage. Threshold values for labrum size should be defined to guide clinical decision making. Ultimately, we require an algorithm to guide arthroscopy versus bony correction.

Inzidenz, Biomechanik und Diagnostik der Hüftgelenkdysplasie

Die Hüftdysplasie ist eine komplexe dreidimensionale Pathomorphologie des gesamten Hüftgelenks. Die mangelhafte Überdachung des Hüftkopfes führt zur Instabilität des Gelenks. Das schräg aufsteigende Dach ist Scherkräften ausgesetzt, die zu einer Überlastung der Erkerregion führen. Die Folge sind Schäden am chondrolabralen Komplex, welche die Ursache für auftretende Schmerzen sind und in weiterer Folge die Dysplasiearthrose induzieren. Die Inzidenz der Hüftdysplasie variiert nach geografischen Regionen und ethnischen Gruppen. Unterschiede in der Definition der Hüftdysplasie und ihrer Diagnose machen Literaturvergleiche schwierig. Die Biomechanik der dysplastischen Hüfte wird von der knöchernen Formgebung, aber auch von der Belastung und Muskelkräften beeinflusst. Die Behandlung sollte die Herstellung einer physiologischen Biomechanik zum Ziel haben, die in den meisten Fällen mehr eine Domäne der offenen Chirurgie als der Arthroskopie darstellt. Die Diagnosestellung der Hüftdysplasie ist herausfordernd. Eine genaue Anamnese, standardisierte klinische Tests und Röntgenaufnahmen, die durch den Chirurgen selbst beurteilt werden müssen, sind essenziell. Weiterführende Untersuchungen wie die Magnetresonanztomographie (MRT) sind für die Beurteilung von Knorpel- und Labrumschäden hilfreich.

Isolated arthroscopic treatment of intra-articular pathologies in mild hip dysplasia: a short-term case control study

PURPOSE

The aim is to compare the results of isolated hip arthroscopy in patients with borderline dysplasia with Lateral center edge angle (LCEA) between 18° and 25° with a control group of patients with normal LCEA (> 25°).

METHODS

Fifty hip arthroscopies performed in 45 patients were retrospectively evaluated. Exclusion criteria were: age > 40, hip arthritis > grade 2 according to Tonnis classification, femoral head avascular necrosis, pediatric's orthopaedics conditions and true dysplasia with LCEA < 18°.Two groups were identified: group A with 15 hips with LCEA between 25° and 18° and Group control B made of 35 hips with LCEA > 25°.

RESULTS

The groups were homogeneous for demography and pre-operative WOMAC and HOOS. Osteoplasty for CAM were performed in 100% of patients in both groups, only in 12 hips (34.4%) in group B we had both femoral and acetabular osteoplasty. Labral repair was performed in 86% of patients in group A, in 60% of patients in group B, capsular plication in 93% of group A, in 5% of case of group B. WOMAC and HOOS statically significant improved in both groups at final follow-up (24 months). No cases in both groups required conversion to total hip arthroplasty. Clinical outcomes of study group were comparable to the control group.

CONCLUSION

Even if the present small series is not conclusive, we suggest isolated arthroscopic management of patients with FAI and LCEA between 18° and 25°, but capsular plication and careful labral management are strongly recommended.

LEVEL OF EVIDENCE

Level IV.

One Bony Morphology, Two Pathologic Entities: Sex-Based Differences in Patients With Borderline Hip Dysplasia Undergoing Hip Arthroscopy

BACKGROUND

Sex-based differences have been largely uncharacterized for patients with borderline hip dysplasia (BHD) undergoing hip arthroscopy.

PURPOSE

To evaluate for sex-based differences in clinical and pathologic characteristics as well as surgical outcomes in patients with BHD undergoing hip arthroscopy.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Between January 2011 and December 2018, data were prospectively collected on all patients with BHD undergoing primary hip arthroscopy. Patients were included if they had preoperative and minimum 2-year postoperative scores for the modified Harris Hip Score (mHHS), Non-arthritic Hip Score (NAHS), and visual analog scale for pain. Patients with previous ipsilateral hip conditions or surgery, Tönnis grade >1, lateral center-edge angle <18° or >25°, or workers' compensation status were excluded. Patients were then divided by sex and propensity score matched in a 1:1 ratio for body mass index, age, and Tönnis grade. The rates of patients who achieved the minimal clinically important difference were recorded for the mHHS and NAHS. The rates of achieving the patient acceptable symptomatic state for the mHHS were calculated.

RESULTS

A total of 344 hips met the inclusion criteria, and 317 hips (92%) had adequate follow-up. Propensity score matching created cohorts of 109 male and 109 female patients. Male patients had significantly higher preoperative average alpha angles (69.79° vs 58.17°, P < .001), more often requiring a femoroplasty (97.2% vs 83.5%, P < .001), and had higher rates of complex labral tearing (50.5% vs 33.0%, P < .001). Male patients also had higher rates of grade 3 and 4 acetabular labral articular disruption (62.4% vs 19.3%, P < .001) and higher rates of grade 3 and 4 acetabular cartilage injury (59.6% vs 20.2%, P < .001) requiring a microfracture more frequently (32.1% vs 7.3%, P < .001). Female patients more typically had painful internal snapping requiring iliopsoas fractional lengthening (60.6% vs 32.1%, P < .001). Female patients also underwent capsular plication more regularly to address hip instability (79.8% vs 45.9%, P < .001). Male and female patients showed significant improvements in all outcome scores after surgery (P < .001). Female patients achieved the minimal clinically important difference for the NAHS at higher rates (85.3% vs 71.6%, P = .020).

CONCLUSION

Female and male patients with BHD who underwent hip arthroscopy achieved favorable outcomes but had notably dissimilar pathology. Hence, although they share similar acetabular bony morphology, male and female patients with BHD may represent 2 very different pathologic entities.