The Utility of Hip Arthroscopy in the Setting of Acetabular Dysplasia: A Systematic Review

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.

Spin Bias Is Common in the Abstracts and Main Body of Systematic Reviews and Meta-analyses of Hip Arthroscopy in the Setting of Borderline Hip Dysplasia

Purpose

To assess the quality and presence of spin bias in the abstracts of systematic reviews and meta-analyses that evaluated the outcomes of using hip arthroscopy for the treatment of hip pathology in the setting of borderline hip dysplasia.

Methods

PubMed and Embase were searched using the terms "borderline hip dysplasia" and "systematic review" or "meta-analysis." Forty-one initial studies were identified, and 12 met the inclusion criteria. Study characteristics were then collected, and each study was evaluated for the 15 most common types of bias and study quality using A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) rating system. Inclusion criteria included a systematic review with or without meta-analysis, published in a peer-reviewed journal, accessible in English, with outcomes after hip arthroscopy for borderline hip dysplasia.

Results

The 12 reviewed studies were published between 2016 and 2023, and 10 of the studies represented Level IV evidence (2 studies were Level III evidence). At least 1 form of spin was identified in 83% (10/12) of the included studies. Regarding the specific categories of spin type, misleading interpretation was identified in 58% (7/12) of the studies, misleading reporting in 67% (8/12) of the studies, and inappropriate extrapolation in 50% (6/12) of the studies. On the basis of the AMSTAR 2 assessment, 92% (11/12) were categorized as either low quality or critically low quality, with 1 study being categorized as moderate.

Conclusions

Spin bias is frequently encountered in the abstracts for systematic reviews and meta-analyses that evaluate outcomes after hip arthroscopy for the treatment of hip pathology in the setting of borderline hip dysplasia.

Level of Evidence

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

The Otto Aufranc Award: Does Hip Arthroscopy at the Time of Periacetabular Osteotomy Improve the Clinical Outcome for the Treatment of Hip Dysplasia? A Multicenter Randomized Clinical Trial

BACKGROUND

A periacetabular osteotomy (PAO) is often sufficient to treat the symptoms and improve quality of life for symptomatic hip dysplasia. However, acetabular cartilage and labral pathologies are very commonly present, and there is a lack of evidence examining the benefits of adjunct arthroscopy to treat these. The goal of this study was to compare the clinical outcome of patients undergoing PAO with and without arthroscopy, with the primary end point being the International Hip Outcome Tool-33 at 1 year.

METHODS

In a multicenter study, 203 patients who had symptomatic hip dysplasia were randomized: 97 patients undergoing an isolated PAO (mean age 27 years [range, 16 to 44]; mean body mass index of 25.1 [range, 18.3 to 37.2]; 86% women) and 91 patients undergoing PAO who had an arthroscopy (mean age 27 years [range, 16 to 49]; mean body mass index of 25.1 [17.5 to 25.1]; 90% women).

RESULTS

At a mean follow-up of 2.3 years (range, 1 to 5), all patients exhibited improvements in their functional score, with no significant differences between PAO plus arthroscopy versus PAO alone at 12 months postsurgery on all scores: preoperative International Hip Outcome Tool-33 score of 31.2 (standard deviation [SD] 16.0) versus 36.4 (SD 15.9), and 12 months postoperative score of 72.4 (SD 23.4) versus 73.7 (SD 22.6). The preoperative Hip disability and Osteoarthritis Outcome pain score was 60.3 (SD 19.6) versus 66.1 (SD 20.0) and 12 months postoperative 88.2 (SD 15.8) versus 88.4 (SD 18.3). The mean preoperative physical health Patient-Reported Outcomes Measurement Information System score was 42.5 (SD 8.0) versus 44.2 (SD 8.8) and 12 months postoperative 48.7 (SD 8.5) versus 52.0 (SD 10.6). There were 4 patients with PAO without arthroscopy who required an arthroscopy later to resolve persistent symptoms, and 1 patient from the PAO plus arthroscopy group required an additional arthroscopy.

CONCLUSIONS

This randomized controlled trial has failed to show any significant clinical benefit in performing hip arthroscopy at the time of the PAO at 1-year follow-up. Longer follow-up will be required to determine if hip arthroscopy provides added value to a PAO for symptomatic hip dysplasia.

Long-term Survivorship and Outcomes of Patients Without Dysplasia Undergoing Capsular Repair During Primary Hip Arthroscopy for Femoroacetabular Impingement Syndrome

BACKGROUND

There is a paucity of literature evaluating long-term outcomes and survivorship of patients undergoing primary hip arthroscopy with capsular repair for femoroacetabular impingement syndrome (FAIS).

PURPOSE

To report 10-year survivorship and patient-reported outcomes (PROs) after primary hip arthroscopy with capsular repair for FAIS and evaluate the effect of capsular repair in patients at the highest risk for conversion to arthroplasty.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data were prospectively collected and retrospectively reviewed on all patients undergoing primary hip arthroscopy with capsular repair between October 2008 and February 2011. Patients with a minimum 10-year follow-up on the modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS), and visual analog scale for pain (VAS) scores were selected. The preoperative and minimum 10-year follow-up Hip Outcome Score-Sports Specific Subscale (HOS-SSS) scores were also reported, if available. Patients with ipsilateral hip surgery, worker's compensation, Tönnis osteoarthritis grade >1, and hip dysplasia (lateral center-edge angle <25°) were excluded. Survivorship, PROS, and clinical benefit-minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS)-were reported. An additional propensity-matched subanalysis was performed on patients at the highest risk for conversion to arthroplasty, comparing patients undergoing capsular repair to patients with unrepaired capsules.

RESULTS

A total of 145 (n = 130 patients) out of 180 eligible hips (n = 165 patients) had a minimum 10-year follow-up (80.6%). Also, 126 hips (86.9%) belonged to women, and 19 hips (13.1%) belonged to men. The mean patient age was 30.3 ± 12.9 years. The survivorship rate was 91% at the 10-year follow-up. The cohort experienced significant improvements (P < .001) in the mHHS, NAHS, HOS-SSS, and VAS for pain scores. Moreover, the cohort achieved high rates of the PASS for the mHHS (89.8%), high rates of the MCID for the mHHS (82.4%), and high rates of the MCID for VAS for pain (80.6%) scores. In the propensity-matched subanalysis performed on patients with the highest risk for arthroplasty, 29 hips with capsular repair were matched to 81 hips with unrepaired capsules. While both groups experienced significant improvements in all PROs (P < .05), the group without capsule repair trended toward a higher conversion to arthroplasty rate when compared with the repair group. In addition, an odds ratio was calculated for the likelihood of converting to arthroplasty after having an unrepaired capsule compared with capsular repair (2.54 [95% CI, 0.873-7.37]; P = .087).

CONCLUSION

Patients undergoing primary hip arthroscopy with capsular repair experienced a high survivorship rate of 91% at a minimum 10-year follow-up. Patients who did not convert to arthroplasty saw favorable improvements in PROs and achieved high clinical benefit rates. In addition, among those patients at the highest risk for conversion to arthroplasty, a trend toward greater survivorship was observed with capsular repair.

Periacetabular osteotomy with and without concomitant arthroscopy: a systematic review of evidence on post-operative activity levels and return to sport

The purpose of this systematic review is to (i) compare post-operative activity levels after periacetabular osteotomy (PAO) versus PAO + HA (concomitant PAO and hip arthroscopy) using patient-reported outcomes that specifically assess activity and sports participation [Hip Disability and Osteoarthritis Outcome Score-Sport and Recreation subscale (HOOS-SR), University of California Los Angeles (UCLA) activity score, Hip Outcome Score-Sport-Specific Subscale (HOS-SSS)] and (ii) compare post-operative return to sport (RTS) data between PAO and PAO + HA groups. A systematic review of literature was conducted on 1 June 2023, utilizing PubMed, Cochrane and Embase (OVID). Articles were screened for inclusion using specific inclusion and exclusion criteria. Twenty-six out of 1610 articles met all inclusion criteria, without meeting any exclusion criteria. In the 12 studies containing only subjects who underwent PAO alone, 11 demonstrated an average score improvement in UCLA, HOOS-SR or HOS-SSS post-operatively (P < 0.05). In the three studies containing subjects who underwent PAO with concomitant HA, significant improvements were seen in the HOS-SS and UCLA scores (P < 0.05). In the five studies that directly compared UCLA, HOS-SSS and HOOS-SSS scores between PAO groups and PAO + HA groups, all demonstrated statistically significant improvement post-operatively (P < 0.05). The rate of RTS ranged from 63% to 90.8% among PAO studies and was found to be 81% in the single PAO + HA study that assessed RTS. When performed in patients with intra-articular pathology, concomitant PAO + HA may provide similar sport-related outcomes to PAO alone in patients without intra-articular pathology.

The Use of Combined Hip Arthroscopy and Periacetabular Osteotomy for Hip Dysplasia Is Increasing and Has Low Complication Rates

Purpose

To analyze the annual use of hip arthroscopy (HA) and Bernese periacetabular osteotomy (PAO) for the treatment of hip dysplasia (HD), as well as postoperative outcomes, including ipsilateral reoperations.

Methods

International Classification of Diseases, Ninth and Tenth Revision, codes were used to query the PearlDiver Mariner database from January 2010 through January 2022 to identify patients aged 10 to 59 years who had a presenting diagnosis of HD and subsequently underwent (1) HA; (2) PAO; or (3) combined HA and PAO (HA-PAO, defined as PAO on the same day or within 28 days after HA). We analyzed annual rates for each treatment, as well as rates of postoperative emergency visits, readmissions, and 5-year ipsilateral secondary operations (determined via Kaplan-Meier analysis).

Results

There were 32,068 patients who underwent surgical treatment of HD. For HA, PAO, and HA-PAO, there were 29,700, 2,083, and 285 patients, respectively. All operations had the greatest percent-increase from 2015 to 2016. HA and HA-PAO peaked in 2021, whereas PAO peaked in 2019. For HA, PAO, and HA-PAO, most cases were performed in female patients and patients aged 30 to 49 years, 10 to 19 years, and 10 to 29 years, respectively. The 5-year incidence of ipsilateral secondary operations, which include revision HA, PAO, or conversion to total hip arthroplasty, was 9.2% (95% confidence interval 8.6%-9.8%) in the HA group and 6.5% (95% confidence interval 4.1%-8.8%) in the PAO group. Combining HA with PAO resulted in so few secondary operations that Kaplan-Meier analysis was infeasible. The PAO cohort had the greatest 30-day emergency visit and 90-day readmission rates, with infection as the most common cause for readmission.

Conclusions

HA is more frequently performed than PAO for hip dysplasia. HA-PAO is increasing at the greatest rate, demonstrating fewer complications and reoperations.

Level of Evidence

Level III, retrospective comparative trial.

Improved Functional Outcomes of Combined Hip Arthroscopy and Periacetabular Osteotomy at Minimum 2-Year Follow-Up

PURPOSE

To evaluate patient-reported outcomes (PROs) and survivorship at minimum 2-year follow-up after combined hip arthroscopy and periacetabular osteotomy (PAO) performed in the setting of a single anesthetic event.

METHODS

Patients who underwent combined hip arthroscopy (M.J.P.) and PAO (J.M.M.) between January 2017 and June 2020 were identified. Preoperative and minimum 2-year postoperative PROs including Hip Outcome Score-Activities of Daily Living (HOS-ADL), HOS-Sport, modified Harris Hip Score (mHHS), Western Ontario and McMaster Universities Osteoarthritis Index, 12-Item Short Form Survey Mental Component Scores (SF-12 MCS), and 12-Item Short Form Survey Physical Component Score were collected and compared in addition to revision rate, conversion to total hip arthroplasty (THA), and patient satisfaction.

RESULTS

Twenty-four of 29 patients (83%) eligible for the study were available for 2-year minimum follow-up with a median follow-up time of 2.5 years (range, 2.0-5.0). There were 19 females and 5 males with mean age of 31 ± 12 years. Mean preoperative lateral center edge angle was 20° ± 5° and alpha angle was 71° ± 11°. One patient underwent reoperation for removal of a symptomatic iliac crest screw at 11.7 months after operation. Two patients, a 33-year-old woman and a 37-year-old man, were converted to THA at 2.6 and 1.3 years, respectively, following the combined procedure. Both patients had a Tönnis grade of 1 on radiographs, as well as bipolar Outerbridge grade III/IV defects requiring microfracture of the acetabulum. For patients who did not convert to THA (n = 22), there was significant improvement from before to after surgery for all scores (P < .05) except SF-12 MCS. The minimal clinically significant difference and patient-acceptable symptom state rates for HOS-ADL, HOS-Sport, and mHHS were 72%, 82%, 86%, and 95%, 91%, and 95%, respectively. Median patient satisfaction was 10 (range, 4 to 10).

CONCLUSIONS

Single-stage combined hip arthroscopy with periacetabular osteotomy for patients with symptomatic hip dysplasia results in improvement in PROs and arthroplasty free survivorship of 92% at median 2.5 year follow-up.

LEVEL OF EVIDENCE

Level IV, case series.

Functional outcome and athletic level after arthroscopic repair followed by triple pelvic osteotomy in patients with labral tears resulting from acetabular dysplasia

BACKGROUND

Patients with acetabular dysplasia are at a higher risk of developing symptomatic labral tears. Isolated treatments that address these pathologies are well established. Combined treatment with hip reorientation osteotomy using Bernese periacetabular osteotomy in addition to arthroscopic labral repair show good results. Studies that report the outcome in patients who received both arthroscopic labral repair and a triple pelvic osteotomy (TPO) are lacking. The aim of this study is to investigate the short to midterm functional outcome and activity level in these patients.

METHODS

This case series retrospectively included 8 patients (2 male, 6 female) with acetabular dysplasia (lateral center-edge angle [LCEA] ≤ 25°) and a labral tear on magnetic resonance arthrography (MRA). All patients underwent arthroscopic labral repair followed by TPO after an average period of 3 months (range 2-6). Average age at the time of surgery was 25 years (range 15-37). Patients were followed up and the following main parameters were assessed: LCEA, modified Harris hip score (mHSS), Tegner score, UCLA score, patient satisfaction on a scale of 1-4.

RESULTS

The mean follow-up was 19 months (range 15-25). The mean LCEA increased from 18° to 37° (p < 0.0001). The mHSS improved from a mean of 79 to 94 on final follow-up (p = 0.00123). The Tegner and UCLA scores had a median of 4 and 5, respectively. The mean LCEA increased from 18° to 37° (p < 0.0001). The mean patient satisfaction was 3.6.

CONCLUSION

Patients with evidence of a labral tear resulting from acetabular dysplasia benefit from arthroscopic repair followed by a TPO. The literature still lacks evidence that labral repair and reorientation osteotomy produce superior outcome compared to osteotomy alone. Treatment should consider clinical presentation in addition to radiological findings with emphasis on MRA.

Patient-Reported Outcomes and Factors Impacting Success of the Periacetabular Osteotomy

Hip dysplasia is a condition affecting both infants and adults, characterized by a shallow acetabulum that does not sufficiently cover the head of the femur. This leads to instability of the hip and elevated levels of mechanical stress around the acetabular rim. A popular procedure for the correction of hip dysplasia is the periacetabular osteotomy (PAO), in which fluoroscopically guided osteotomies around the pelvis are made to allow for repositioning of the acetabulum to fit properly on the femoral head. This systematic review aims to analyze patient factors that impact outcomes, as well as patient-reported outcomes such as the Harris Hip Score (HHS) and the Western Ontario and McMaster Universities Arthritis Index (WOMAC). The patients in this review did not undergo any prior intervention for acetabular hip dysplasia, allowing for an unbiased reporting of outcomes from all included studies. Of studies reporting HHS, the mean preoperative HHS was 68.92 and the mean postoperative HHS was 89.1. Of the study that reported mHHS, the mean preoperative mHHS was 70, and the mean postoperative mHHS was 91. Of the studies reporting WOMAC, the mean preoperative WOMAC was 66, and the mean postoperative WOMAC was 63. Key findings of this review are that of the seven included studies, six achieved a minimally important clinical difference (MCID) based on patient-reported outcomes, and factors impacting outcome are preoperative Tönnis osteoarthritis (OA) grade, pre and postoperative lateral-center edge angle (LCEA), preoperative hip joint congruency, postoperative Tönnis angle, and age. In patients with no prior intervention for hip dysplasia, the PAO is a successful procedure with significant improvement in postoperative patient-reported outcomes. Despite the reported success of the PAO, proper patient selection is vital to avoid early conversions to total hip arthroplasty (THA) and prolonged pain. However, further investigation is prompted regarding the long-term survivorship of the PAO in patients with no prior intervention for hip dysplasia.

The Effects of Arthroscopic Labral Repair on Patient-Reported Outcomes in the Setting of Periacetabular Osteotomy

BACKGROUND

It is currently unknown whether the addition of arthroscopic labral repair in the setting of periacetabular osteotomy (PAO) provides any clinical benefit.

PURPOSE/HYPOTHESIS

The purpose of this study was to compare outcomes of patients who underwent arthroscopic labral repair concomitantly with PAO versus patients who underwent PAO alone. We hypothesized that there would be no difference in patient-reported outcome measures (PROMs) between the cohorts.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients undergoing PAO from a single-center prospective hip preservation registry were eligible for this study if they completed pre- and postoperative PROMs (minimum, 1 year). PROMs were collected at 1 year, 2 years, and latest follow-up at 6.05 years for PAO group and 4.2 years for scope/PAO group. The study group consisted of 53 patients who underwent arthroscopic labral repair at the time of their PAO, and the comparison group consisted of 170 patients who underwent PAO alone. A subset of the PAO group who had radiologic evidence of a detached labral tear (n = 33) was also compared with the rest of the PAO-alone group. PROMs were compared at every time point for both groups as well as the subset of patients who underwent PAO alone despite a labral tear.

RESULTS

The mean follow-up of all patients was 2 years (range, 1-6 years). Overall, 85.2% of the PAO group and 85.7% of the scope/PAO group met the minimal clinically important difference for either the modified Harris Hip Score (mHHS) or the International Hip Outcome Tool (iHOT-33) at the most recent follow-up. There was no difference in improvement between groups (mHHS, P = .670; iHOT-33, P = .944). Patients who had a radiologically diagnosed detached labral tear and underwent PAO alone had no difference in outcomes when compared with the rest of the PAO cohort (mHHS, P = .981; iHOT-33, P = .909).

CONCLUSION

There was no significant benefit measured by PROMs at follow-up for concomitant arthroscopic labral repair in the setting of PAO.

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.

Use of Anatomic Radiographic Horizons for the Lateral Center-Edge Angle in the Classification of Hip Dysplasia

BACKGROUND

The lateral center-edge angle of Wiberg (LCEA) and Tönnis angle (TA) rely on a "horizon" that functions as a reference point for measurements of hip dysplasia on weightbearing anteroposterior pelvis radiographs. There are 3 different horizons that are currently utilized depending on surgeon preference: (1) a line parallel to the radiographic floor (F), (2) a line that connects the inferior portions of the acetabular teardrops (ATs), or (3) a line that connects the ischial tuberosities (ITs). It is imperative to accurately assess the degree of hip dysplasia on initial workup to select the appropriate surgical intervention.

PURPOSE

To assess how the choice of a radiographic horizon affects the measurements of the LCEA and TA. The secondary purpose was to assess how the horizon affected the classification of hips as either normal, borderline dysplastic, or dysplastic.

STUDY DESIGN

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

METHODS

The LCEA and TA were measured on all preoperative weightbearing anteroposterior pelvis radiographs for 186 consecutive patients who underwent hip preservation surgery between February 2016 and November 2020 (140 hip arthroscopic procedures, 46 combined hip arthroscopic procedures with periacetabular osteotomy), 3 times per hip, each time using an F, AT, and IT horizon. The Student t test was used to analyze the differences in the measurements of the LCEA and TA, and discordance rates in the dysplasia classification between horizons were quantified.

RESULTS

For the entire study population, the mean LCEA_F (23.4°± 7.4°) was significantly greater than the mean LCEA_IT (23.1°± 7.2°) (95% CI, -0.634 to -0.003; P = .047) and mean LCEA_AT (23.0°± 7.1°) (95% CI, -0.723 to -0.139; P = .004). There was no difference between the LCEA_IT and LCEA_AT (95% CI, -0.305 to 0.080; P = .251). When stratified by hip arthroscopic surgery, the mean LCEA_F (26.3°± 5.6°) was significantly greater than the mean LCEA_AT (25.8°± 5.3°) (95% CI, -0.845 to -0.162; P = .004). Overall, there was a 17.7% and 18.3% discordance rate in the dysplasia classification using the LCEA_IT and LCEA_AT compared with the LCEA_F, respectively. There were no statistically significant differences between the mean TA_IT, TA_AT, and TA_F for the entire study population, the arthroscopic surgery group, and the combined arthroscopic surgery and periacetabular osteotomy group.

CONCLUSION

There was no statistical difference between the AT and IT horizons for LCEA measurements. The dysplasia classification was in better agreement between the 2 anatomic horizons compared with the F horizon. The TA was not affected by changes in the horizon.

Presence of a Posterior Wall Sign in the Treatment of Femoroacetabular Impingement Syndrome: A Matched Comparative Cohort Analysis at Minimum 2-Year Follow-Up

BACKGROUND

Acetabular retroversion may predispose to more severe femoroacetabular impingement syndrome (FAIS) and early labral damage given impaction of the femoral head-neck junction on the retroverted acetabular rim. The cross-over sign (COS), posterior wall sign (PWS), and ischial spine sign (ISS) are markers of acetabular retroversion (AR) on plain radiographs.

METHODS

Patients who underwent primary hip arthroscopy for FAIS from January 2012 to December 2018 with a positive PWS were matched in a 1:1 ratio by age, gender, and body mass index (BMI) to controls with a negative PWS. Preoperative and postoperative patient-reported outcomes (PROs; HOS-ADL, HOS-SS, mHHS, and iHOT-12) were compared using independent t-tests. Achievement of a Patient Acceptable Symptom State (PASS) or Minimal Clinically Important Difference (MCID) was compared using Fisher's exact test.

RESULTS

Two hundred and seventy five patients with a positive PWS and 275 controls were included in the final analysis. Most patients (64%) were female, with average age, and BMI of 37.6 (SD 8.6) and 25.1 (SD 4.4), respectively. PROs improved significantly for both groups from preoperatively to 2 years postoperatively. There were no statistically significant differences (P ≥ .05) in PROs or achievement of MCID or PASS. On a subgroup analysis, patients with all three positive signs had significantly lower postoperative PROs and lower rates of achievement of MCID and PASS.

CONCLUSION

Patients with an isolated PWS achieve similar outcomes following hip arthroscopy at 2 years. However, patients with a concomitant PWS, ISS, and COS demonstrate less favorable outcomes, suggesting the need for increased perioperative counseling and potential evaluation for planned concurrent or serial open procedures such as periacetabular osteotomy.

Surgical Treatment of Acetabular Dysplasia With Labral Tears

Acetabular dysplasia results in abnormal forces across the hip joint and can result in both labral tears and cartilage degeneration. A continuum exists from classic dysplasia to normal acetabular morphology. Diagnosis is aided by several radiographic measurements and parameters including a lateral center edge angle of less than 20°, an anterior center edge angle of less than 20°, a Sharp's angle of greater than 42°, and a Tonnis angle of greater than 10°, or version abnormalities. When patients with acetabular dysplasia present with intra-articular hip pain, skeletal maturity, and preserved radiographic joint space, a periacetabular osteotomy (PAO) is considered as a surgical treatment option when conservative measures have failed. The Bernese PAO was developed in 1984 as a way for reorienting the acetabulum to restore more normal femoral head coverage and orientation. The long-term results of this procedure have been promising with 10-year and 20-year survivorships of approximately 85% and 60%, respectively. When dysplasia is coupled with a labral tear or other intra-articular pathology including focal chondral damage, ligamentum teres tears, or capsular defects, hip arthroscopy and PAO are performed. Although there is a paucity in the literature of the long-term evidence for the combined procedure, early results indicate improved patient reported outcome measures. Appropriate treatment of borderline hip dysplasia remains controversial.

A comparison of 6-month outcomes between periacetabular osteotomy with concomitant hip arthroscopy to isolated hip arthroscopy for femoroacetabular impingement

PURPOSE

To compare early outcomes of periacetabular osteotomy (PAO) with concomitant hip arthroscopy to isolated hip arthroscopy for femoroacetabular impingement (FAI) and chondrolabral pathology using patient-reported outcomes measurement information system (PROMIS).

MATERIALS AND METHODS

Consecutive patients scheduled for PAO with concomitant hip arthroscopy (PAO + HA) or isolated hip arthroscopy (HA) between the ages of 15 and 30 years old were prospectively included in the study. Based on power analysis, subjects were recruited until there were 22 subjects in the PAO + HA group. These subjects were then gender matched to the HA group. The PROMIS, with six subscales and two global health measures, were completed during preoperative and 6-month follow-up visits. One-way ANOVA was performed to compare intake information of age, symptom duration, body mass index, and Beighton scores as well as preoperative and 6-month postoperative PROMIS scores between the PAO + HA and HA.

RESULTS

22 consecutive subjects undergoing PAO + HA were all females (average age 20.0 years) and matched to 22 consecutive females (average age 22.6) in the HA group. ANOVA did not find a significant difference between the two groups when comparing intact information, with exception of age (p = 0.04). A significant difference was also not identified (p ≥ 0.05) between the two groups on preoperative or 6-month postoperative PROMIS scores. The largest difference in 6-month postoperative scores between the two groups was 4.4 points on physical function subscale.

CONCLUSION

Outcomes at 6 months were not significantly different when comparing PAO + HA to HA for FAI and chondrolabral pathology in females under 30 years of age. The more extensive surgery with a prolonged protective period associated with PAO do not seem to negatively impact outcomes at 6 months when compared to HA. These finding support the use of PAO + HA, particularly if the patient and/or surgeon were concerned about prolonged disability, metal health issues, and/or higher pain levels that might be associated with the PAO procedure.

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.

Costs of open, arthroscopic and combined surgery for developmental dysplasia of the hip

A variety of options exist for management of patients with developmental dysplasia of the hip (DDH). Most studies to date have focused on clinical outcomes; however, there are currently no data on comparative cost of these techniques. The purpose of this study was to evaluate in-hospital costs between patients managed with periacetabular osteotomy, hip arthroscopy or a combination for DDH. One hundred and nine patients were included: 35 PAO + HA, 32 PAO and 42 HA. There were no significant differences in the demographic parameters. Operative times were significantly different between groups with a mean of 52 min for PAO, 100 min for HA and 155 min for PAO + HA, (P < 0.001). Total direct medical costs were calculated and adjusted to nationally representative unit costs in 2017 inflation-adjusted dollars. Total in-hospital costs were significantly different between each of the three treatment groups. PAO + HA was the most expensive with a median of $21 852, followed by PAO with a median of $15 124, followed by HA with a median of $11 582 (P < 0.001). There was a significant difference between outpatient median costs of $11 385 compared with $24 320 for inpatients (P < 0.001). Procedures with greater complexity were more expensive. However, a change from outpatient to inpatient status with HA moved that group from the least expensive to similar to PAO and PAO + HA. These data provide an important complement to clinical outcomes reports as surgeons and policymakers aim to provide optimal value.

Computed Tomography-Based Three-Dimensional Analyses Show Similarities in Anterosuperior Acetabular Coverage Between Acetabular Dysplasia and Borderline Dysplasia

PURPOSE

(1) To compare the acetabular coverage between dysplasia, borderline dysplasia, and control acetabulum in a quantitative 3-dimensional manner; and (2) to evaluate correlations between the radiologic parameters and the 3-dimensional zonal-acetabular coverage.

METHODS

We reviewed contralateral hip computed tomography images of patients 16 to 60 years of age who underwent 1 of 3 types of surgeries: eccentric rotational acetabular osteotomy, curved intertrochanteric varus osteotomy, and total hip replacement with minimum 1-year follow-up from January 2013 to April 2018. A point-cloud model of the acetabulum created from computed tomography was divided into 6 zones. Three-dimensional acetabular coverage was measured radially at intervals of 1°. Mean radial acetabular coverage for each zone was named ZAC (zonal acetabular coverage) and was compared among the 3 subgroups (control: 25° ≤lateral center-edge angle [LCEA] <40°; borderline: 20° ≤LCEA <25°; and dysplasia: LCEA ≤20°) statistically. Further, the correlations between the ZAC in each zone and the LCEA were analyzed using Pearson's correlation coefficient.

RESULTS

One-hundred fifteen hips were categorized as control (36 hips), borderline (32 hips), and dysplasia (47 hips). The mean anterocranial ZAC in the borderline (87.5 ± 5.7°) was smaller than that in the control (92.6 ± 5.9°, P = .005) but did not differ compared with the dysplasia (84.5 ± 7.6°, P = .131). In contrast, the anterocaudal (71.2 ± 5.0°), posterocranial (85.0 ± 6.4°), and posterocaudal (82.4 ± 4.5°) mean ZACs in the borderline were not different from those in the control (anterocaudal, 74.3 ± 4.6°, P = .090; posterocranial, 87.9 ± 4.3°, P = .082; posterocaudal, 85.1 ± 5.0°, P = .069) respectively. Although there was a very strong positive correlation with supra-anterior ZAC and LCEA (r = 0.750, P < .001), the correlation between the anterocranial ZAC and LCEA was relatively weak (r = 0.574, P < .001).

CONCLUSIONS

The anterosuperior acetabular coverage in the borderline dysplastic acetabulum is more similar to the dysplastic acetabulum than to the normal acetabulum.

CLINICAL RELEVANCE

This study emphasizes the importance of evaluating not only the lateral but also the anterior coverage in borderline dysplasia.

Periacetabular osteotomy with or without arthroscopic management in patients with hip dysplasia: study protocol for a multicenter randomized controlled trial

Background

Hip dysplasia is one of the most common causes of hip arthritis. Its incidence is estimated to be between 3.6 and 12.8% (Canadian Institute for Health Information, Hip and knee replacements in Canada, 2017–2018: Canadian joint replacement registry annual report, 2019; Jacobsen and Sonne-Holm, Rheumatology 44:211–8, 2004). The Periacetabular Osteotomy (PAO) has been used successfully for over 30 years (Gosvig et al., J Bone Joint Surg Am 92:1162–9, 2010), but some patients continue to exhibit symptoms post-surgery (Wyles et al., Clin Orthop Relat Res 475:336–50, 2017). A hip arthroscopy, performed using a small camera, allows surgeons to address torn cartilage inside the hip joint. Although both procedures are considered standard of care treatment options, it is unknown whether the addition of hip arthroscopy improves patient outcomes compared to a PAO alone. To delay or prevent future joint replacement surgeries, joint preservation surgery is recommended for eligible patients. While previous studies found an added cost to perform hip arthroscopies, the cost-effectiveness to Canadian Health care system is not known.

Methods

Patients randomized to the experimental group will undergo central compartment hip arthroscopy prior to completion of the PAO. Patients randomized to the control group will undergo isolated PAO. Patient-reported quality of life will be the primary outcome used for comparison between the two treatment groups as measured by The International Hip Outcome Tool (iHOT-33) (Saberi Hosnijeh et al., Arthritis Rheum 69:86–93, 2017). Secondary outcomes will include the four-square step test and sit-to-stand (validated in patients with pre-arthritic hip pain) and hip-specific symptoms and impairment using the HOOS; global health assessment will be compared using the PROMIS Global 10 Score; health status will be assessed using the EQ-5D-5L and EQ VAS questionnaires (Ganz et al., Clin Orthop Relat Res 466:264–72, 2008) pre- and post-operatively. In addition, operative time, hospital length of stay, adverse events, and health services utilization will be collected. A sub-group of patients (26 in each group) will receive a T1rho MRI before and after surgery to study changes in cartilage quality over time. A cost-utility analysis will be performed to compare costs and quality-adjusted life years (QALYs) associated with the intervention.

Discussion

We hypothesize that (1) concomitant hip arthroscopy at the time of PAO to address central compartment pathology will result in clinically important improvements in patient-reported outcome measures (PROMs) versus PAO alone, that (2) additional costs associated with hip arthroscopy will be offset by greater clinical improvements in this group, and that (3) combined hip arthroscopy and PAO will prove to be a cost-effective procedure.

Trial registration

ClinicalTrials.gov NCT03481010. Registered on 6 March 2020. Protocol version: version 3.

A Contemporary Look at the Evaluation and Treatment of Adult Borderline and Frank Hip Dysplasia

BACKGROUND

Adult hip dysplasia is often diagnosed according to the lateral center-edge angle (LCEA). Patients with frank hip dysplasia (LCEA <20°) traditionally require treatment with bony realignment through a periacetabular osteotomy (PAO) and/or derotational femoral osteotomy, while patients with borderline hip dysplasia (BHD) present a challenging treatment dilemma, as it remains unknown when they should be treated with hip arthroscopy and/or a PAO.

PURPOSE

To perform a narrative review to report the differences in hip morphology and clinical outcomes between adult patients with frank hip dysplasia and BHD.

STUDY DESIGN

Narrative review.

METHODS

A systematic search of the literature was conducted through the Medline, EMBASE, and Cochrane databases with the search phrase borderline hip dysplasia.

RESULTS

The search identified 305 articles, of which 48 were considered relevant to this study after screening of titles and abstracts. Four articles discussed new radiographic means of evaluating adult hip dysplasia, 16 articles analyzed morphology of dysplastic hips, and 28 articles described the clinical outcomes of patients with frank hip dysplasia or BHD treated with hip arthroscopy and/or PAO. Because the level of evidence obtained from this search was not adequate for systematic review or meta-analysis, a current concepts review on the diagnosis, hip morphology, and clinical outcomes of patients with frank hip dysplasia or BHD is presented.

CONCLUSION

Adult hip dysplasia is most commonly diagnosed based on the LCEA; however, the LCEA is an unreliable sole marker for dysplasia, and additional radiographic parameters should be utilized. Furthermore, specific pathology identified on imaging and/or during hip arthroscopy can provide clues to a surgeon when the diagnosis is inconclusive according to history and physical examination alone. While the data support that patients with frank dysplasia are best treated with PAO, there is no such preferred treatment for patients with BHD, who have a wide spectrum of instability. Selective use of arthroscopic labral and capsular treatment alone may provide good results in carefully chosen patients with BHD, while some may end up requiring a bony realignment procedure.

Acetabular Morphologic Characteristics Predict Early Conversion to Arthroplasty After Isolated Hip Arthroscopy for Femoroacetabular Impingement

BACKGROUND

Hip arthroscopy in the setting of dysplasia and borderline dysplasia is controversial. Dysplasia severity is most often defined by the lateral center edge angle (LCEA) but can also be evaluated radiographically by the acetabular inclination (AI).

PURPOSE/HYPOTHESIS

The purpose was to determine the effect of AI on outcomes after isolated hip arthroscopy for femoroacetabular impingement (FAI). We hypothesized that patients with dysplasia would have higher rates of arthroplasty as well as inferior clinical and functional outcomes compared with patients who did not have dysplasia.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A hip arthroscopy registry was reviewed for participants undergoing arthroscopic correction of FAI from February 28, 2008, to June 10, 2013. Participants required a clinical diagnosis and isolated arthroscopic correction of FAI with preoperative imaging and intraoperative cartilage status recorded. AI dysplasia was defined as an AI greater than 10°, LCEA dysplasia as LCEA less than 18°, and borderline LCEA dysplasia as LCEA 18° to 25°. Patients without an acetabular deformity (LCEA 25°-40°; AI <10°) served as a control population. Postoperative variables included patient-reported outcome surveys with conversion to arthroplasty as the primary endpoint. Minimum 5-year outcome scores were obtained for 337 of 419 patients (80.4%) with an average follow-up of 75.2 ± 12.7 months.

RESULTS

This study included 419 patients: 9 (2%) with LCEA dysplasia, 42 (10%) with AI dysplasia, and 51 (12%) with borderline dysplasia. The AI but not LCEA was significantly correlated with lower outcome scores on the modified Harris Hip Score (r = 0.13; P = .01), Non-Arthritic Hip Score (r = 0.10; P = .04), and Hip Outcome Score-Sports Subscale (r = 0.11; P = .04). A total of 58 patients (14%) underwent arthroplasty at 31 ± 20 months postoperatively. Patients with LCEA dysplasia had an arthroplasty rate of 56% (odds ratio, 8.4), whereas patients with AI dysplasia had an arthroplasty rate of 31% (odds ratio, 3.3), which was significantly greater than the rate for the nondysplastic cohort (13.5%; P < .0001). Patients with borderline LCEA dysplasia did not have increased rates of arthroplasty. A multivariate analysis found increasing age, increasing AI, Tönnis grade higher than 1, and femoral Outerbridge grade higher than 2 to be most predictive of conversion to arthroplasty.

CONCLUSION

We found that an elevated AI, along with increasing age, Tönnis grade, and femoral Outerbridge grade significantly predict early conversion to arthroplasty after isolated hip arthroscopy. We recommend using the AI, in addition to the LCEA, in evaluating hip dysplasia before hip arthroscopy.

Is the Femoro-Epiphyseal Acetabular Roof (FEAR) index on MRI a relevant predictive factor of instability in a borderline dysplastic hip?

AIMS

A borderline dysplastic hip can behave as either stable or unstable and this makes surgical decision making challenging. While an unstable hip may be best treated by acetabular reorientation, stable hips can be treated arthroscopically. Several imaging parameters can help to identify the appropriate treatment, including the Femoro-Epiphyseal Acetabular Roof (FEAR) index, measured on plain radiographs. The aim of this study was to assess the reliability and the sensitivity of FEAR index on MRI compared with its radiological measurement.

PATIENTS AND METHODS

The technique of measuring the FEAR index on MRI was defined and its reliability validated. A retrospective study assessed three groups of 20 patients: an unstable group of 'borderline dysplastic hips' with lateral centre edge angle (LCEA) less than 25° treated successfully by periacetabular osteotomy; a stable group of 'borderline dysplastic hips' with LCEA less than 25° treated successfully by impingement surgery; and an asymptomatic control group with LCEA between 25° and 35°. The following measurements were performed on both standardized radiographs and on MRI: LCEA, acetabular index, femoral anteversion, and FEAR index.

RESULTS

The FEAR index showed excellent intraobserver and interobserver reliability on both MRI and radiographs. The FEAR index was more reliable on radiographs than on MRI. The FEAR index on MRI was lower in the stable borderline group (mean -4.2° (sd 9.1°)) compared with the unstable borderline group (mean 7.9° (sd 6.8°)). With a FEAR index cut-off value of 2°, 90% of patients were correctly identified as stable or unstable using the radiological FEAR index, compared with 82.5% using the FEAR index on MRI. The FEAR index was a better predictor of instability on plain radiographs than on MRI.

CONCLUSION

The FEAR index measured on MRI is less reliable and less sensitive than the FEAR index measured on radiographs. The cut-off value of 2° for radiological FEAR index predicted hip stability with 90% probability. Cite this article: Bone Joint J 2019;101-B:1578-1584.

Editorial Commentary: Patient Profiling: Identifying Risk Factors That Help Predict Outcomes of Hip Arthroscopy Candidates

Hip pain in the young athletic population is often caused by femoroacetabular impingement morphology. If a patient fails conservative management, hip arthroscopy becomes a potential treatment option. Our ability to maximize patient outcomes after hip arthroscopy is directly related to preoperative patient selection, intraoperative technical ability, and attention to detail in the postoperative period. When considering surgery as a therapeutic option, we want to first identify that the pain is truly stemming from the hip. Once the hip is identified as the culprit, then we proceed with the responsibility of discussing pros and cons and risks and benefits to each patient to critically evaluate whether surgical treatment is a viable option. With the explosion of literature in the field of hip preservation, we have recognized certain modifiable and nonmodifiable risk factors that aid us in identifying patients who may have difficulty in achieving their functional athletic expectations after surgery.

Automatic MRI-based Three-dimensional Models of Hip Cartilage Provide Improved Morphologic and Biochemical Analysis

BACKGROUND

The time-consuming and user-dependent postprocessing of biochemical cartilage MRI has limited the use of delayed gadolinium-enhanced MRI of cartilage (dGEMRIC). An automated analysis of biochemical three-dimensional (3-D) images could deliver a more time-efficient and objective evaluation of cartilage composition, and provide comprehensive information about cartilage thickness, surface area, and volume compared with manual two-dimensional (2-D) analysis.

QUESTIONS/PURPOSES

(1) How does the 3-D analysis of cartilage thickness and dGEMRIC index using both a manual and a new automated method compare with the manual 2-D analysis (gold standard)? (2) How does the manual 3-D analysis of regional patterns of dGEMRIC index, cartilage thickness, surface area and volume compare with a new automatic method? (3) What is the interobserver reliability and intraobserver reproducibility of software-assisted manual 3-D and automated 3-D analysis of dGEMRIC indices, thickness, surface, and volume for two readers on two time points?

METHODS

In this IRB-approved, retrospective, diagnostic study, we identified the first 25 symptomatic hips (23 patients) who underwent a contrast-enhanced MRI at 3T including a 3-D dGEMRIC sequence for intraarticular pathology assessment due to structural hip deformities. Of the 23 patients, 10 (43%) were male, 16 (64%) hips had a cam deformity and 16 (64%) hips had either a pincer deformity or acetabular dysplasia. The development of an automated deep-learning-based approach for 3-D segmentation of hip cartilage models was based on two steps: First, one reader (FS) provided a manual 3-D segmentation of hip cartilage, which served as training data for the neural network and was used as input data for the manual 3-D analysis. Next, we developed the deep convolutional neural network to obtain an automated 3-D cartilage segmentation that we used as input data for the automated 3-D analysis. For actual analysis of the manually and automatically generated 3-D cartilage models, a dedicated software was developed. Manual 2-D analysis of dGEMRIC indices and cartilage thickness was performed at each "full-hour" position on radial images and served as the gold standard for comparison with the corresponding measurements of the manual and the automated 3-D analysis. We measured dGEMRIC index, cartilage thickness, surface area, and volume for each of the four joint quadrants and compared the manual and the automated 3-D analyses using mean differences. Agreement between the techniques was assessed using intraclass correlation coefficients (ICC). The overlap between 3-D cartilage volumes was assessed using dice coefficients and means of all distances between surface points of the models were calculated as average surface distance. The interobserver reliability and intraobserver reproducibility of the software-assisted manual 3-D and the automated 3-D analysis of dGEMRIC indices, thickness, surface and volume was assessed for two readers on two different time points using ICCs.

RESULTS

Comparable mean overall difference and almost-perfect agreement in dGEMRIC indices was found between the manual 3-D analysis (8 ± 44 ms, p = 0.005; ICC = 0.980), the automated 3-D analysis (7 ± 43 ms, p = 0.015; ICC = 0.982), and the manual 2-D analysis.Agreement for measuring overall cartilage thickness was almost perfect for both 3-D methods (ICC = 0.855 and 0.881) versus the manual 2-D analysis. A mean difference of -0.2 ± 0.5 mm (p < 0.001) was observed for overall cartilage thickness between the automated 3-D analysis and the manual 2-D analysis; no such difference was observed between the manual 3-D and the manual 2-D analysis.Regional patterns were comparable for both 3-D methods. The highest dGEMRIC indices were found posterosuperiorly (manual: 602 ± 158 ms; p = 0.013, automated: 602 ± 158 ms; p = 0.012). The thickest cartilage was found anteroinferiorly (manual: 5.3 ± 0.8 mm, p < 0.001; automated: 4.3 ± 0.6 mm; p < 0.001). The smallest surface area was found anteroinferiorly (manual: 134 ± 60 mm; p < 0.001, automated: 155 ± 60 mm; p < 0.001). The largest volume was found anterosuperiorly (manual: 2343 ± 492 mm; p < 0.001, automated: 2294 ± 467 mm; p < 0.001). Mean average surface distance was 0.26 ± 0.13 mm and mean Dice coefficient was 86% ± 3%. Intraobserver reproducibility and interobserver reliability was near perfect for overall analysis of dGEMRIC indices, thickness, surface area, and volume (ICC range, 0.962-1).

CONCLUSIONS

The presented deep learning approach for a fully automatic segmentation of hip cartilage enables an accurate, reliable and reproducible analysis of dGEMRIC indices, thickness, surface area, and volume. This time-efficient and objective analysis of biochemical cartilage composition and morphology yields the potential to improve patient selection in femoroacetabular impingement (FAI) surgery and to aid surgeons with planning of acetabuloplasty and periacetabular osteotomies in pincer FAI and hip dysplasia. In addition, this validation paves way to the large-scale use of this method for prospective trials which longitudinally monitor the effect of reconstructive hip surgery and the natural course of osteoarthritis.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Editorial Commentary: Hip Arthroscopy in Dysplastic Hip Population? A Must, a Maybe, or a No Go?

Treating symptomatic patients with dysplasia involves a controversy in therapy. The question is whether to obtain osseous correction with the help of pelvic reorientation osteotomy or to address intra-articular pathology with an arthroscopic approach. Neither isolated therapy nor the other method seems to be sufficient, but conducting both treatment options simultaneously has also not proved to be superior and carries the risk of additional complications. Different treatment options have been presented on this topic over the years and should be considered on a case-by-case basis. Pelvic reorientation osteotomy in patients with moderate to severe acetabular dysplasia remains uncontested, but it lacks the ability to obtain visualization of the central hip compartment. The isolated arthroscopic approach seems to be favorable for treatment of intra-articular pathologies in patients with mild to borderline dysplasia, whereas collateral arthroscopy in pelvic reorientation osteotomy may achieve better clinical outcomes in patients with more complex cases.