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

Minimal Clinically Important Difference, Substantial Clinical Benefit, and Patient Acceptable Symptom State Values After Hip Arthroscopy for Femoroacetabular Impingement Are Highly Dependent on Their Study Population and Calculation Methods: A Systematic Review

PURPOSE

To provide a summary of available literature on the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptom state (PASS) after hip arthroscopy for femoroacetabular impingement (FAI).

METHODS

A systematic review was conducted via the Cochrane Library, PubMed, Ovid MEDLINE, and Embase to identify studies that calculated MCID, SCB, or PASS for patient-reported outcome measures after hip arthroscopy for FAI. The electronic search strategy used was as follows: hip AND arthroscopy AND (MCID OR "minimal clinically important difference" OR SCB OR "substantial clinical benefit" OR PASS OR "patient acceptable symptom state"). Inclusion criteria were English-language studies published from 1980 to 2023 reporting clinical outcome scores and calculated values of MCID, PASS, or SCB for patients undergoing hip arthroscopy for FAI.

RESULTS

Forty-two studies (5 Level II, 19 Level III, and 18 Level IV) met inclusion and exclusion criteria. The most commonly used outcome measures across MCID, SCB, and PASS were the Hip Outcome Score sports-specific subscale and the activities of daily living subscale, the modified Harris Hip Score, and the 12-item international Hip Outcome Tool. The range of MCID values for Hip Outcome Score sports-specific subscale, Hip Outcome Score activities of daily living subscale, modified Harris Hip Score, and 12-item international Hip Outcome Tool were 7.2-15.7, 7.3-15.4, 7.2-16.8, and 8.8-16.2 respectively. Similarly, for SCB the values ranged from 77.9-96.9, 90.4-98.5, 20.0-98.4, and 66.7-87.5, respectively. Lastly, the PASS values ranged from 63.9-80.9, 85.9-99.2, 74.0-97.0, and 59.5-86.0, respectively.

CONCLUSIONS

MCID, SCB, and PASS values for patient-reported outcome measures after hip arthroscopy for the management of FAI are highly dependent on their associated study including study population and calculation methods.

LEVEL OF EVIDENCE

IV, systematic review of Level II-IV studies.

Evaluating the Corrected Femoroepiphyseal Acetabular Roof Index in Patients With Borderline Dysplasia Undergoing Periacetabular Osteotomy or Hip Arthroscopy

Background

Identifying hip instability in symptomatic patients with borderline dysplasia of the hip (BDH) is of paramount importance, as it can influence both surgical decision-making and surgical outcomes. The femoroepiphyseal acetabular roof (FEAR) index is strongly affected by the hip adduction/abduction angle during the pelvic radiograph, which has not yet been considered in the recommended threshold values.

Purpose

To compare the corrected FEAR index in symptomatic patients with BDH treated with pelvic periacetabular osteotomy (PAO) or hip arthroscopy.

Study Design

Cohort study; Level of evidence, 3.

Methods

Patients with symptomatic hips and radiographical BDH were categorized into 2 cohorts. The first cohort included patients treated with PAO (n = 42) and the second cohort consisted of patients treated with hip arthroscopy due to symptomatic femoroacetabular impingement (n = 50). All patients presented with good patient-reported outcomes at the final follow-up. The FEAR index was measured on the pelvic radiograph at the initial hip adduction/abduction angle (uncorrected FEAR index) and after correcting the hip abduction angle to 0° (corrected FEAR index). Negative values of the FEAR index represent a lateral closing angle, whereas positive values represent a lateral opening angle. As for the hip adduction/abduction angle, negative values represent adduction, whereas positive values represent abduction.

Results

The corrected FEAR index varied significantly from the uncorrected FEAR index in both groups with a mean difference of 6°± 4° in patients treated with PAO and 5°± 5° in patients treated with hip arthroscopy. The corrected FEAR index in patients with BDH treated with hip arthroscopy (-11°± 8°) was significantly lower (P < .001) compared with the patients with BDH treated with PAO (-7°± 7°) (Table 1). The optimal threshold for the corrected FEAR index was -13° (odds ratio, 7.8 [95% CI, 2.6-23.1]; P < .001), which yielded a sensitivity of 85% and a specificity of 52%, distinguishing the 2 surgical cohorts.

Conclusion

The corrected FEAR index might vary significantly from the uncorrected FEAR index, which is highly dependent on the hip adduction/abduction angle during the pelvic radiograph. Symptomatic patients with BDH treated with PAO exhibit a corrected FEAR index of ≥-13° compared with those with BDH treated with hip arthroscopy for impingement symptomatology.

Radiographic evaluation of the painful adolescent and young adult hip

Radiographic evaluation of hip pain in adolescents and young adults is an important component of the assessment to aid in the identification of the cause of pain, distinguish between etiologies of early hip degeneration such as acetabular dysplasia (instability) and femoroacetabular impingement, and guide further workup and management. Recent advances in radiographic assessment include the importance of obtaining a standing anterior-posterior radiograph to illustrate the functional position of the pelvis, the use of anterior and posterior wall indices to illustrate anterior and posterior wall coverage and the importance of interpreting radiographic measures in the context of a patient's sagittal balance. Advances in magnetic resonance imaging, computed tomography, and ultrasound have also occurred and can provide further diagnostic clarity. The purpose of this work is to review the literature to provide a systematic approach to the radiographic evaluation of hip pain in skeletally mature adolescents and young adults.

Key Concepts

(1)The standing AP pelvis, 45° Dunn, and false-profile views provide a preliminary comprehensive radiographic assessment of the symptomatic hip in the skeletally mature adolescent and young adult and help to distinguish between instability and impingement.(2)The Lateral Center Edge Angle (LCEA) should be augmented by the anterior center edge angle (ACEA), anterior wall index (AWI), and posterior wall index (PWI) to obtain a more complete understanding of 3-dimensional femoral head coverage from plain radiographs.(3)While the crossover and posterior wall signs on radiographs can be helpful in screening for acetabular retroversion and anteversion, CT should be used to confirm if considering reorientation or resection.(4)Cam morphology should be quantitatively assessed using the alpha angle and head-neck offset on the 45° Dunn view.(5)Dynamic ultrasound may be useful in illustrating the motion associated with impingement and instability in real-time but may be limited by the technician-dependent nature of this modality.

Editorial Commentary: Arthroscopy With Labral Preservation or Reconstruction Plus Capsular Closure Shows Excellent Outcome in Patients With Borderline Hip Dysplasia and is Less Invasive Than Periacetabular Osteotomy

Borderline developmental dysplasia of the hip (BDDH), or borderline hip dysplasia (BHD), traditionally characterized by a relatively low lateral center-edge angle (LCEA), presents a complex challenge in treatment due to its multifaceted etiology involving instability, femoroacetabular impingement (FAI), or a combination thereof. The optimal approach to managing adult BDDH remains a subject of significant debate. Periacetabular osteotomy (PAO) is considered the preferred treatment for addressing severe acetabular under-coverage, as it rectifies the underlying bony deficiency and promotes stability. However, the treatment of BDDH is less straightforward, particularly with the advancement of hip arthroscopy techniques, specifically labral preservation and capsular management. Given the minimally invasive and rapid postoperative rehabilitation advantage for arthroscopic procedures over open surgeries, numerous attempts have been undertaken in this context. Research has revealed favorable patient-reported outcomes (PROs), low failure rates, and a significant proportion of returning to sports (RTS) after arthroscopic management for patients with BDDH. Although we might in the right direction, Level I evidence studies are needed to comprehensively compare long-term PROs, failure rates, and rates of RTS between arthroscopy and PAO in the treatment of BDDH.

Hip microinstability and its association with femoroacetabular impingement: A scoping review

Introduction

Hip microinstability has become a recognized cause of non-arthritic hip pain and disability in young patients. However, its pathophysiology remains unclear. We want to (1) present an overview of the evidence of hip microinstability and of its association with femoroacetabular impingement (FAI), (2) map out the type of evidence available, and (3) make recommendations for future research.

Methods

A deductive analysis and extraction method was used to extract information. In addition, diagnostic accuracy statistics were extracted or calculated.

Results

Of the 2,808 identified records, 123 were eligible for inclusion. Different definitions for microinstability exist. A standardized terminology and clear diagnostic criteria are lacking. FAI and microinstability may be associated and may aggravate each other. Conservative treatment strategies for FAI and microinstability are similar. The reported prevalence of microinstability in combination with FAI ranges from 21% to 42% in adults undergoing hip arthroscopy or magnetic resonance arthrography (MRA) of the hip.

Conclusion

Hip microinstability and FAI may be associated, occur together, or exacerbate each other. To better address this topic, a standardized terminology for microinstability is essential. Achieving consensus on physical examination and diagnosis is also necessary. Initial efforts to establish uniform diagnostic criteria have been made, but further work is needed. Specifically, randomized controlled trials are required to evaluate the effectiveness of training programmes aimed at reducing symptoms in individuals with microinstability, with or without FAI. Such studies will enable clinicians to manage microinstability with greater confidence within this context.

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.

Borderline Dysplastic Hips Undergoing Hip Arthroscopy Achieve Equivalent Patient Reported Outcomes When Compared With Hips With Normal Acetabular Coverage: A Systematic Review and Meta-Analysis

PURPOSE

To systematically review and meta-analyze studies reporting lateral center edge angle as it relates to patient-reported outcome (PRO) measures and clinically notable outcome assessments for patients undergoing hip arthroscopy for femoroacetabular impingement syndrome or labral pathology with borderline dysplastic hips (BDH).

METHODS

PubMed, EMBASE, and the Web of Science Core Collection databases were queried for articles evaluating lateral center edge angle as a predictor of PRO after hip arthroscopy. Articles were eligible for meta-analysis if they compared PROs measures between patients with normal acetabular coverage and borderline dysplasia and were at least level III evidence. Continuous random-effects models with standardized mean differences were used to compare postoperative Hip Outcome Score-Activities of Daily Living and sports subscales, modified Harris Hip Score, international Hip Outcome Tool scores, Satisfaction, and Visual Analog Scale Pain scores between normal coverage and borderline dysplastic groups.

RESULTS

Overall, 989 hips undergoing arthroscopy from six investigations were included in this meta-analysis, including 315 borderline dysplastic subjects (mean age 27.5 years) and 674 subjects with normal coverage (mean age 26.9 years). Borderline dysplastic and normal coverage cohorts were followed for an average of 37.0 and 36.8 months, respectively. Postoperative PRO measures (Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale, modified Harris Hip Score, international Hip Outcome Tool-12, Satisfaction, and Visual Analog Scale Pain) collected approximately three years after hip arthroscopy were not markedly different between subjects with BDH when compared with patients with normal coverage.

CONCLUSIONS

In a meta-analysis of the available literature, patients with BDH are able to equally reach statistically similar clinical outcomes after isolated hip arthroscopy as compared with control subjects without dysplasia at short-term follow-up. A BDH should not be considered a contraindication to hip arthroscopy when optimal PRO achievement is the goal.

LEVEL OF EVIDENCE

Level III, Systematic Review and Meta-Analysis.

Outcomes of Periacetabular Osteotomy for Borderline Acetabular Dysplasia

BACKGROUND

The optimal surgical treatment (hip arthroscopy compared with periacetabular osteotomy [PAO]) for borderline acetabular dysplasia (lateral center-edge angle [LCEA], 18° to 25°) remains a topic of debate. To date, the literature has focused primarily on arthroscopy outcomes, with only a few small reports on PAO outcomes. The purpose of this study was to define PAO outcomes in a large cohort of borderline hips. In a secondary analysis, we assessed the effect of prior failed arthroscopy, concurrent hip arthroscopy, and concurrent femoral osteoplasty on PAO outcomes in this cohort.

METHODS

A prospective database was retrospectively reviewed for patients who underwent PAO for symptomatic instability in the setting of borderline dysplasia (LCEA, 18° to 25°). Of the 232 identified hips, 186 (80.2%) were assessed at a mean follow-up of 3.3 ± 2.0 years postoperatively. The mean patient age was 25.2 ± 8.5 years (range, 14 to 45 years), and 88.2% were female. Thirty hips (16.1%) had undergone a failed prior arthroscopy. Arthroscopy was performed concurrently with the PAO in 130 hips (69.9%), and femoral osteoplasty was performed concurrently in 120 hips (64.5%). The modified Harris hip score (mHHS) was assessed relative to the minimal clinically important difference (MCID) of 8 and patient acceptable symptom state (PASS) of 74. Clinical failure was defined as a reoperation for persistent symptoms or a failure to achieve either the mHHS MCID or PASS.

RESULTS

Of the 156 hips undergoing a primary surgical procedure, clinical success was achieved in 148 hips (94.9% [95% confidence interval (CI), 90.2% to 97.4%]). Two hips (1.3% [95% CI, 0.4% to 4.6%]) underwent reoperation (hip arthroscopy) for persistent symptoms and an additional 6 hips (3.8% [95% CI, 1.8% to 8.1%]) failed to achieve the mHHS MCID or PASS, for a clinical failure rate of 5.1% (95% CI, 2.6% to 9.8%); 8.8% reported dissatisfaction with the surgical procedure. Clinical failure was more frequent among the 30 hips (23.3% [95% CI, 11.8% to 40.9%]; p = 0.001) that had undergone a prior failed arthroscopy. There were no outcome differences between hips that had or had not undergone concurrent hip arthroscopy or femoral osteoplasty.

CONCLUSIONS

This study demonstrates excellent early outcomes of PAO for borderline acetabular dysplasia, with significant clinical improvement in 94.9% of patients undergoing a primary surgical procedure; 91.2% were satisfied with the surgical procedure.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

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.

Editorial Commentary: Hip Arthroscopy for Femoroacetabular Impingement in Patients With Borderline Dysplasia Does Not Result in Inferior Outcomes Compared With Outcomes in Patients Without Dysplasia: Do Not Fear

The treatment of adult borderline hip dysplasia remains challenging and continues to be a subject of controversy. The preferred treatment for hip instability and acetabular undercoverage is periacetabular osteotomy. However, patients with painful hips and associated femoroacetebular impingement, microinstability, or no instability may benefit from arthroscopic surgery. Short-term studies have reported favorable clinical outcomes. Traditionally, the lateral center-edge angle was used to determine hip dysplasia. More recently the femoro-epiphyseal acetabular roof (FEAR) index was introduced as a measure for borderline dysplasia. In general, a FEAR index of less than 5° indicates hip instability. When using a FEAR index of more than 2° as a cut-off for hip instability and borderline dysplasia, arthroscopic hip surgery can achieve very similar clinical outcomes to patients with a FEAR index of less than 2°. However low and unequal sample sizes have potentially resulted in both type I and II errors, reducing internal study validity. Although this may be a step in the right direction, further high-quality studies are required to understand patients' characteristics on diagnosis, prognosis, outcomes of surgical interventions, and long-term disease progression for adult borderline hip dysplasia.