Outcomes for Arthroscopic Treatment of Anterior Inferior Iliac Spine (Subspine) Hip Impingement

Surgical Hip Dislocation in the Era of Hip Arthroscopy Demonstrates High Survivorship and Improvements in Patient-reported Outcomes for Complex Femoroacetabular Impingement

BACKGROUND

Over the past decade, hip arthroscopy has become more commonly used in the treatment of patients with femoroacetabular impingement (FAI) as well as those with many other intra-articular hip pathologies. As such, the indications for open surgical hip dislocation have narrowed to include complex intra-articular and extra-articular bony morphologies and revision hip preservation. Although surgical hip dislocation has been established as an effective approach, previous research using contemporary indications has been limited primarily to smaller cohorts with short-term follow-up. Furthermore, factors associated with reoperation, conversion arthroplasty, and not achieving clinical improvement remain ambiguous.

QUESTIONS/PURPOSES

At a minimum of 2 years of follow-up in patients treated for FAI with surgical hip dislocation, (1) how much did patient-reported outcome measures (PROMs) improve, and what percentage of patients achieved the minimum clinically important difference (MCID) and patient-acceptable symptom state (PASS)? (2) What was the survivorship free from reoperation of the hip for any reason? (3) What was the survivorship free from conversion to arthroplasty (THA or hip resurfacing)?

METHODS

Between February 2011 and April 2021, 211 patients were treated at one academic institution with surgical dislocation and osteoplasty of the femoral head-neck junction or greater trochanter for FAI. Of these, patients with concomitant diagnoses including Legg-Calvé-Perthes disease, slipped capital femoral epiphysis, osteochondritis dissecans, a benign tumor, or another neurologic or metabolic disorder were excluded. This yielded 74% (156 of 211) of patients as potentially eligible. A further 12% (18 of 156) of patients without postoperative PROMs were excluded, and another 13% (21 of 156) were lost before the minimum study follow-up of 2 years, leaving 75% (117) for analysis at a median of 4.9 years (range 2 to 12 years) in this retrospective study. A total of 88% of the patients were women (103 of 117), and 40% (47 patients) underwent the procedure as a revision. All patients underwent surgical hip dislocation. Intraoperatively, 66% (77 of 117) of patients demonstrated cam impingement, and the remainder had either pincer impingement or combined cam and pincer; 82% (96 of 117) had some component of extra-articular impingement. To answer our first research question, we obtained PROM scores for the modified Harris hip score (mHHS) and international hip outcome tool 12 (iHOT-12) before surgery and at the most-recent follow-up from our longitudinally maintained institutional database, and we determined the percentage of patients who achieved the MCID or PASS. To answer our second research question, we calculated Kaplan-Meier survivorship free from any reoperation on the hip at 5.8 years (mean follow-up) after the index procedure. To answer our third research question, we calculated the Kaplan-Meier survivorship free from conversion to arthroplasty at 5.8 years. Using univariate logistic regression analysis, factors associated with meeting these defined endpoints were identified.

RESULTS

At a mean of 6 ± 3 years, the mHHS of patients treated with surgical hip dislocation for FAI who had not had previous surgery on the hip improved from 53 ± 15 to 85 ± 13 (mean difference 31 [95% confidence interval 27 to 36]; p < 0.01) and the mean iHOT-12 score improved from 25 ± 14 to 74 ± 24 (mean difference 49 [95% CI 42 to 56]; p < 0.01). At a mean of 5 ± 3 years, for patients with prior hip surgery, mHHS improved from 55 ± 13 to 79 ± 15 (mean difference 24 [95% CI 18 to 30]; p < 0.01) and iHOT-12 scores improved from 25 ± 16 to 66 ± 26 (mean difference 41 [95% CI 31 to 50]; p < 0.01). The proportion of patients who achieved the MCID for the mHHS was 87% (55 of 63) and 83% (33 of 40), while the proportion who achieved the PASS for the mHHS was 66% (46 of 70) and 51% (24 of 47) for primary and revision surgery, respectively. The proportion of patients who achieved the MCID for the iHOT-12 was 87% (53 of 61) and 83% (33 of 40), while the proportion who achieved the PASS for iHOT-12 was 68% (47 of 69) and 57% (26 of 46) for primary and revision surgery, respectively. Higher lateral center-edge angles (odds ratio 1.2 per 1° [95% CI 1.1 to 1.3]; p < 0.01), a lower acetabular version at 2:00 (OR 0.92 per 1° [95% CI 0.85 to 0.99]; p = 0.05), the absence of a labral tear (OR 0.21 [95% CI 0.06 to 0.79]; p = 0.02), a higher preoperative mHHS (OR 1.1 per 1 point [95% CI 1.02 to 1.2]; p < 0.01), and a higher preoperative iHOT-12 score (OR 1.1 per 1 point [95% CI 1.01 to 1.1]; p = 0.01) were associated with not achieving the MCID. In patients without a history of ipsilateral hip surgery, survivorship free from reoperation at 5.8 years after surgical hip dislocation was 90% (95% CI 82% to 98%). In the setting of prior ipsilateral hip surgery, survivorship free from reoperation at 5.8 years after surgical hip dislocation was 75% (95% CI 60% to 95%). No patients for whom surgical hip dislocation was their primary hip procedure underwent conversion to arthroplasty. Among the revision patient cohort, survivorship free from conversion to arthroplasty at 5.8 years after surgical hip dislocation was 97% (95% CI 91% to 100%).

CONCLUSION

Surgical hip dislocation effectively improves hip pain and function with high survivorship (free of reoperation or conversion to arthroplasty) for complex intra-articular and extra-articular FAI that is deemed less suitable for arthroscopic treatment, but when the procedure is used in patients who have had prior hip surgery, they should be told that revision surgery is a realistic possibility. If insufficient acetabular coverage is anticipated, acetabular reorientation osteotomy should be considered. Future studies should evaluate long-term survivorship and PROMs in larger patient cohorts, as well as identify other factors associated with reoperation and conversion to arthroplasty.

LEVEL OF EVIDENCE

Level III, therapeutic study.

A comprehensive review of hip arthroscopy techniques and outcomes

Transforming the orthopedic landscape, hip arthroscopy pioneers a minimally invasive surgical approach for diagnosing and addressing hip pathologies. With its origins dating back to Burman's 1931 cadaveric study, this groundbreaking technique gained clinical relevance in 1939 through Takagi's report. However, the 1980s marked the actual emergence of hip arthroscopy for treating a wide range of hip disorders. Now, a staple in modern orthopedics, hip arthroscopy empowers patients with previously undiagnosed and untreated hip conditions, enabling them to obtain relief and reclaim their lives. By employing a compact camera and specialized tools, surgeons expertly navigate the hip joint, performing procedures from excising loose bodies and mending labral tears to addressing femoroacetabular impingement and tackling other intricate issues. This innovative approach has dramatically elevated patients' quality of life, allowing them to embrace targeted treatments and resume daily activities without resorting to lifestyle alterations.

Intermediate-Term Outcomes of Hip Arthroscopy for Femoroacetabular Impingement Syndrome in Patients With Global Versus Isolated Lateral Acetabular Overcoverage

BACKGROUND

Previous studies evaluating the outcomes of hip arthroscopy for patients with global acetabular overcoverage and focal superolateral acetabular overcoverage suffer from short-term follow-up and inconsistent radiographic criteria when defining these subpopulations of patients with femoroacetabular impingement syndrome (FAIS).

PURPOSE

To evaluate the intermediate-term postoperative outcomes for patients with FAIS in the setting of global acetabular overcoverage, lateral acetabular overcoverage, and normal acetabular coverage.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients undergoing hip arthroscopy for FAIS were enrolled in a prospective cohort study, and those with a minimum follow-up of 5 years were included in this analysis. Patients were grouped based on type of acetabular coverage: global overcoverage (lateral center-edge angle [LCEA] ≥40°, with coxa profunda), lateral overcoverage (LCEA ≥40°, without coxa profunda), and no overcoverage (LCEA <40°). Functional outcomes (modified Harris Hip Score and Nonarthritic Hip Score) and failure of primary hip arthroscopy were compared between groups.

RESULTS

In total, 94 patients (mean age, 41.9 ± 14.2 years) were included with a mean follow-up duration of 6.1 ± 0.9 years. Of these patients, 40.4% had no acetabular overcoverage, 36.2% had lateral overcoverage, and 23.4% had global overcoverage. There was no difference between groups with respect to percentage of patients who underwent reoperation for either revision arthroscopy or conversion to total hip arthroplasty (28.9% for the normal acetabular coverage group, 29.4% for the lateral overcoverage group, and 31.8% for the global overcoverage group; P = .971). Among patients for whom primary hip arthroscopy did not fail, there was no difference in 5-year functional outcomes between groups. Postoperative LCEA >40° (β = -13.3; 95% CI, -24.1 to -2.6; P = .016), female sex (β = -14.5; 95% CI, -22.7 to -6.2; P = .001), and higher body mass index (β = -1.9; 95% CI, -2.8 to -1.0; P < .001) were associated with worse intermediate-term hip function in terms of modified Harris Hip Score.

CONCLUSION

There was no difference in functional outcomes or rate of reoperation at a minimum of 5 years postoperatively between those with global acetabular overcoverage, those with regional lateral overcoverage, and those with normal acetabular coverage. Provided that an appropriate acetabuloplasty is performed, there is no evidence to suggest that global acetabular overcoverage portends a worse prognosis than other FAIS subtypes.

Sex-Based Differences in Prevalence, Outcomes, and Complications of Hip Arthroscopy for Femoroacetabular Impingement: A Systematic Review and Meta-analysis

Background

Trends between the sexes have been reported regarding prevalence, patient-reported outcomes (PROs), and complications of hip arthroscopy (HA) for femoroacetabular impingement syndrome (FAIS), yet current results lack consensus.

Purpose

To evaluate sex-based differences after HA for FAIS in (1) prevalence of cam and pincer morphology in FAIS and (2) PROs, pain scores, and postoperative complication rates.

Study Design

Systematic review; Level of evidence, 4.

Methods

The EMBASE, PubMed, and Ovid (MEDLINE) databases were searched from establishment to February 28, 2022, according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Included studies had sex-based data on prevalence, outcomes, and complications of HA for FAIS. Reviews and commentaries were excluded. Data were combined, and between-sex differences were analyzed. Meta-analyses using random-effects models were performed when possible. Pooled risk ratios (RRs) and standardized mean differences were calculated.

Results

A total of 74 studies were included (213,059 patients; 132,973 female hips [62.4%] and 80,086 male hips [37.6%]). The mean age was 30.7 ± 7.7 years among male patients and 31.1 ± 7.8 years among female patients. Male patients experienced mixed-type impingement significantly more often (39.4% vs 27.2% for female patients; RR = 0.69 [95% confidence interval [CI], 0.58-0.81]; P < .001), whereas female patients experienced pincer-type impingement more often (50.6% vs 30.8% for male patients; RR = 2.35 [95% CI, 1.14-4.86]; P = .02). Male patients had higher likelihoods of undergoing femoroplasty (89.8% vs 77.4% for female patients; RR = 0.90 [95% CI, 0.83-0.97]; P = .006), acetabuloplasty (67.1% vs 59.3% for female patients; RR = 0.87 [95% CI, 0.79-0.97]; P = .01), or combined femoroplasty/acetabuloplasty (29.2% vs 14.5% for female patients; RR = 0.63 [95% CI, 0.44-0.90]; P = .01). Although female patients showed greater improvements in Hip Outcome Score-Sport-Specific subscale (P = .005), modified Harris Hip Score (P = .006), and visual analog scale pain (P < .001), both sexes surpassed the minimal clinically important difference at 1, 2, and 5 years postoperatively. Female patients had higher complication rates (P = .003), although no sex-based differences were found in total hip arthroplasty conversion rates (P = .21).

Conclusion

Male patients undergoing HA for FAIS had a higher prevalence of mixed-type FAIS while female patients had more pincer-type FAIS. Female patients gained greater improvements in PROs, although both sexes exceeded the minimal clinically important difference, suggesting that both male and female patients can benefit from HA.

Outcomes of Arthroscopic Decompression of the Anterior Inferior Iliac Spine: A Systematic Review and Meta-analysis

BACKGROUND

Anterior inferior iliac spine (AIIS) impingement has been increasingly recognized as a source of extra-articular impingement and hip pain. However, no aggregate data analysis of patient outcomes after AIIS decompression has been performed.

PURPOSE

To evaluate outcomes after arthroscopic AIIS decompression.

STUDY DESIGN

Meta-analysis; Level of evidence, 4.

METHODS

A systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. PubMed, EMBASE, and Cochrane Central Register of Controlled Trials were queried for all English-language studies reporting outcomes of arthroscopic AIIS decompression performed in isolation or in conjunction with hip impingement correction surgery. After screening, 10 articles were included. The indications for AIIS decompression were recorded, and weighted mean improvements in patient-reported outcome (PRO) scores, complication rates, and revision rates were calculated.

RESULTS

A total of 547 patients (311 women; 57%) were identified, with a total of 620 operative hips. The mean age was 28.42 ± 5.6 years, and the mean follow-up was 25.22 ± 11.1 months. A total of 529 hips (85%) underwent AIIS decompression, 530 hips (85%) underwent femoral osteochondroplasty, and 458 hips (74%) underwent labral repair. Of the patients, 13% underwent bilateral AIIS decompression. The mean modified Harris Hip Score improved from 61.3 ± 6.9 to 88.7 ± 4.7 postoperatively (change, 27.4 ± 5.7 points; P < .001), the Hip Outcome Score-Activities of Daily Living improved from 67.2 ± 10.6 to 91.1 ± 3.2 postoperatively (change, 24.0 ± 8.0 points; P = .001), and the Hip Outcome Score-Sports Specific Subscale improved from 36.8 ± 19.2 to 82.8 ± 3.8 postoperatively (change, 46.0 ± 18.2 points; P = .002). The pooled risk of postoperative complications was 1.1% (95% CI, 0.1%-2.1%), and the pooled risk of needing revision surgery was 1.0% (95% CI, 0.1%-2.0%). No complication was directly attributed to the AIIS decompression portion of the procedure.

CONCLUSION

PROs improved significantly after hip arthroscopy with AIIS decompression, with a low risk of postoperative complications and subsequent revision surgeries. Failure to identify extra-articular sources of hip pain in outcomes of femoroacetabular impingement syndrome, including from the AIIS, could lead to poorer outcomes and future revision surgery.

Subspine femoroacetabular impingement: retrospective study of a series of patients treated by hip arthroscopic resection

BACKGROUND

Femoroacetabular impingement syndrome (FAIS) is a common hip pathology that causes pain and functional limitation in young patients. subspine femoroacetabular impingement (SFAI) is an increasingly diagnosed extra-articular subtype that occurs from mechanical conflict of the anteroinferior iliac spine (AIIS) with the cervico-diaphyseal junction during hip flexion, which is poorly described in the literature.

QUESTIONS/PURPOSES

We aimed to describe the clinical, functional, and radiological results of the arthroscopic treatment of a group of patients with SFAI treated in our Hip Unit.

STUDY DESIGN

Case series.

METHODS

We present a retrospective study of ten patients with SFAI treated between 2013 and 2020 with arthroscopic resection. Clinical results were assessed with scales such as visual analog scale (VAS); modified Harris Hip Score (mHHS), and Hip disability and Osteoarthritis Outcome Score (HOOS). Radiological results were assessed with radiological measurements, magnetic resonance imaging (MRI), and computed tomography (CT) reconstructions.

RESULTS

Six patients had a Type III AIIS and four of them had Type II. Two patients had previously been surgically treated for FAIS. The range of motion improved in flexion from 107 ± 11 degrees before surgery to 127.5 ± 6 degrees (p = 0.005). MHHS improved from 48.1 (38-75.3) before surgery to 83.1 (57-91) (p = 0.007) and HOOS improved from 65.2 (58-75) to 89 (68.1-100) (p = 0.007). VAS improved from 7.3 (5-9) pre-surgical to 2.5 (0-8) post-surgical (p = 0.005). We did not have significant complications except for an asymptomatic case of heterotopic ossification (Brooker I).

CONCLUSION

Arthroscopic decompression of AIIS in SFAI patients is a safe procedure that provides satisfactory short-term functional results, improving clinical symptoms, function, sports performance, and range of motion in our study.

A comparison between ultrasound-guided AIIS injection and radiography in the diagnosis of subspine impingement in patients with FAI

BACKGROUND

Subspine impingement (SSI) does not have effective diagnostic criteria, especially in patients who also have femoroacetabular impingement (FAI). The classification of anterior inferior iliac spine (AIIS) morphology via three-dimensional CT is controversial.

PURPOSE

To propose a method for ultrasound-guided AIIS injection as a way to diagnose SSI and evaluate the accuracy of radiography methods, including 3-D CT and MRI, as well as intraoperative findings.

METHODS

Patients diagnosed with FAI between September 2020 and December 2021 were evaluated in this prospective study. Those who met the criteria were included in the ultrasound-guided AIIS injection test. Whether the pain was relieved after injection was recorded in the radiology report. Patients who experienced significant relief of the anterior groin pain (more than 50%) after the AIIS injection were considered positive responders. Among these patients, radiography materials, including AIIS morphology as measured by 3-D CT as well as superior capsular oedema on MRI, were compared. The presence of congestion or bruising on the capsule side of the labrum corresponding to the AIIS during hip arthroscopy was recorded.

RESULTS

A total of 73 patients with FAI underwent the ultrasound-guided AIIS injection test. Prevalence rates of 13.70% (10/73), 58.90% (43/73), 23.29% (17/73) and 4.11% (3/73) were recorded for Type I, Type IIA, Type IIB and Type III AIISs, respectively. Thirty-six patients had positive responses to injection, and 37 patients had negative responses to injection. None of the patients with Type I, 23 (53.49%) patients with Type IIA, 11 (64.71%) patients with Type IIB and 2 (66.7%) patients with Type III AIISs had positive responses to the injection. A total of 57.14% of patients with Type II or Type III AIIS had positive responses to the injection. The proportions of patients with superior capsular oedema on MRI in the Type I, Type IIA, Type IIB, and Type III AIIS groups was 0, 30.23, 29.41 and 0%, respectively. Among non-Type I AIIS patients, those who reported positive responses to the injection had a higher incidence of superior capsular oedema (38.89% vs. 14.81%, P = 0.036), but they had no significant differences in the proportion of congestion or bruising of the labrum (47.22% vs. 37.04%, P = 0.419). The results showed that no pairs of methods-ultrasound-guided injection, MRI, and intraoperative findings-achieved good consistency (κ = 0.222, κ = 0.098 and κ = - 0.116).

CONCLUSIONS

Radiographic methods including 3-D CT and MRI as well as the intraoperative findings of the labrum cannot be considered an accurate and reliable basis for the diagnosis and treatment of SSI in FAI patients. It is suggested that ultrasound-guided AIIS injections be combined with radiography to better diagnose SSI.

LEVEL OF EVIDENCE

IV, case series.

The narrow subspine space and relatively large labrum are radiographic features of subspine impingement: a case-control study

Background

Subspine impingement is considered a source of residual hip symptoms after primary hip arthroscopy, and the role of the subspine space and soft tissue is not clear. The purpose of this study was to analyze the relationship between the subspine space and labrum size in subspine impingement patients.

Methods

We performed a retrospective study of patients with femoroacetabular impingement between July 2016 and July 2020. Sixteen patients without hip symptom relief after primary hip arthroscopic treatment of femoroacetabular impingement and undergoing revision surgery for anterior inferior iliac spine compression were included as the study group. Forty-eight matched patients who underwent only primary surgery and whose hip discomfort was relieved without a diagnosis of subspine impingement were included as the control group. The patients’ preoperative computerized tomography data were reviewed, and the anterior inferior iliac spine dimensions and the size of the subspine space were measured. The size of the labrum at the 11:30, 1:30, and 3 o’clock positions was measured with the use of magnetic resonance imaging. The ratio of the subspine space to the labrum was also calculated.

Results

There was no significant difference in anterior inferior iliac spine dimensions between these two groups (p > 0.05). A relatively narrow subspine space was found in the study group, especially in the direction of the anterior inferior iliac spine. Compared with the control group, subspine impingement patients were identified with larger labrums at 11:30 (8.20 ± 1.95 mm vs. 6.81 ± 0.50 mm, p = 0.016), 1:30 (7.83 ± 1.61 mm and 6.25 ± 0.78 mm, p = 0.001) and 3:00 (9.50 ± 1.73 mm vs. 7.48 ± 0.99 mm, p = 0.001). A relative mismatch between the subspine space and the labrum was also identified in the study group. The ratios of the labrum width to the subspine area were significantly larger in the study group than in the control group.

Conclusion

This study reported potential additional criteria for subspine impingement—a large labrum and a relatively narrow subspine space—instead of abnormal anterior inferior iliac spine dimensions. For those with a large labrum and narrow subspine space, the diagnosis of subspine impingement should be carefully made, and arthroscopic anterior inferior iliac spine decompression may be important.

Arthroscopic Subspine Decompression Is Commonly Reported in a Heterogenous Patient Population With Concomitant Procedures: A Systematic Review

PURPOSE

To systematically review the evaluation, management, and surgical outcomes of arthroscopic subspine decompression in conjunction with other intra-articular hip preservation procedures.

METHODS

Two databases (PubMed and Embase) were searched from 2010 to 2021, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, for articles investigating arthroscopic subspine decompression using the key words: "subspine impingement", "AIIS impingement", and "extra-articular impingement." Exclusion criteria included diagnostic studies, failure to report postoperative outcomes, and case series of less than 10 hips. Studies were assessed for patient demographics, diagnostic criteria, clinical findings, concomitant procedures, outcomes, and postoperative complications. The quality of the studies was analyzed by 2 independent reviewers (A.J.C. and A.E.J.) using the Methodological Index for Non-randomized Studies (MINORS).

RESULTS

Ten studies consisting of 438 patients (460 hips, 48.6% female) met the inclusion criteria, with average ages and follow-up ranging from 24.9 to 34.7 years and 6.0 to 44.4 months, respectively. There was 1 Level II study, 3 Level III studies, and 6 Level IV studies. The MINORS criteria yielded an average quality assessment of 13.0 (range: 7-22), with 3 methodological domains demonstrating mean scores of less than 1: unbiased assessment of the study endpoint (.25), loss of follow up less than 5% (.25), and prospective calculation of the study size (.7). The most common exam maneuver used was the subspine impingement test (9 studies). Most subspine decompressions were performed in addition to traditional femoroacetabular impingement syndrome (FAIS) procedures, with only one study (33 hips) reporting solely on isolated subspine osteoplasty. Average preoperative and postoperative modified Harris Hip Score (mHHS) values ranged from 44.93 to 75.7 and 79.5 to 98.0, respectively. Three studies noted improved hip flexion in the postoperative period. Five surgical complications were reported.

CONCLUSIONS

Arthroscopic subspine decompression is commonly reported in a heterogenous patient population with intra-articular hip pathology. A combination of the subspine impingement test and anterior inferior iliac spine (AIIS) morphology on imaging is frequently used for diagnosis. While improved patient-reported outcomes (PROs) are consistently observed following arthroscopic decompression, conclusions are limited by study methodology and concurrent procedures performed at the time of surgery.

LEVEL OF EVIDENCE

IV, systematic review of Level II through Level IV studies.

Minimum 2-Year Outcomes and Return to Sports of Competitive Athletes Who Undergo Subspine Decompression During Primary Hip Arthroscopy for Femoroacetabular Impingement Syndrome and Subspine Impingement: A Propensity-Matched Controlled Study

BACKGROUND

Patient-reported outcomes (PROs) and return to sports (RTS) have not been established in athletes undergoing primary hip arthroscopy and subspine decompression for femoroacetabular impingement syndrome (FAIS) and subspine impingement (SSI).

PURPOSE

(1) To report minimum 2-year PROs and RTS in competitive athletes undergoing primary hip arthroscopy for treatment of FAIS with subspine decompression for treatment of SSI and (2) to compare clinical results with a matched control group of athletes without SSI.

STUDY DESIGN

Cohort study, Level of evidence, 3.

METHODS

Data were reviewed for professional, collegiate, and high school athletes undergoing primary hip arthroscopy for FAIS with arthroscopic subspine decompression for SSI between February 2011 and October 2018. Inclusion criteria included preoperative and minimum 2-year follow-up scores for the modified Harris Hip Score, Nonarthritic Hip Score, Hip Outcome Score-Sport Specific Subscale, and visual analog scale for pain. Rates of achieving the minimal clinically important difference (MCID) were also calculated. For comparison, athletes in the SSI group were propensity matched according to age at the time of surgery, sex, body mass index, lateral center-edge angle, alpha angle, sport level, acetabular labrum articular disruption grade, and sport type to a control group of athletes without SSI.

RESULTS

A total of 30 SSI athletes were included in the study, with a mean plus or minus standard deviation follow-up of 32.1 ± 7.1 months and age of 20.9 ± 5.7 years. The SSI cohort demonstrated significant improvement in all recorded PROs (P < .001), returned to sports at high rates (88.5%), and achieved the MCID for the Hip Outcome Score-Sport Specific Subscale at a high rate (80.0%). Furthermore, these patients had a low rate of undergoing revision surgery (6.7%). When compared with a propensity-matched control group of 59 athletes, the SSI group demonstrated similar rates of RTS, revision, and achieving the MCID for all PROs.

CONCLUSION

Competitive athletes with FAIS and SSI who underwent primary hip arthroscopy and subspine decompression had favorable outcomes and high RTS rates at minimum 2-year follow-up. These results were comparable with those of a control group of athletes without SSI undergoing primary hip arthroscopy.

Editorial Commentary: Low-Radiation Dose 3-Dimensional Computed Tomography Scan Reconstruction Is the Best Way to Visualize the Anterior Inferior Iliac Spine-For Now

Femoroacetabular impingement comes in several anatomic variations that may coexist, and subspine impingement is a commonly discussed cause of indirect extra-articular hip pathology. Although a classification system to identify and understand anterior inferior iliac spine morphology has been in place for some time, attempts have been made to visualize and understand the anatomy based on other imaging modalities. Standard radiographs are a common part of the initial patient evaluation pathway, along with thorough history taking and physical examination findings. Magnetic resonance imaging scans are obtained typically to evaluate the soft tissue, muscle, ligaments, articular cartilage, and labrum for pathology. For many hip preservation surgeons, a computed tomography scan with 3-dimensional reconstruction is standard protocol for patients who progress along the treatment pathway toward a surgical procedure because understanding the complex hip anatomy is key to successful surgical treatment. Many hip arthroscopy patients are in their young adult years, and we always attempt to reduce the amount of radiation exposure. Eliminating this computed tomography scan and using standard-of-care magnetic resonance imaging to simplify patient care, reduce radiation, and reduce health care costs would certainly be beneficial to our hip preservation patients.

Editorial Commentary: The Everted Acetabular Labrum. It Is Not Just a Small Labrum

Everted, hypoplastic acetabular labra represent a variant of acetabular rim development. It is important to be able to recognize this pathology on magnetic resonance imaging and at the time of hip arthroscopy. Proper intraoperative identification of this variant that does not make contact with the femoral head is critical to being able to successfully restore this contact, often through labral advancement, acetabuloplasty of the abnormal rim development, and occasionally labral augmentation. A broad awareness among hip arthroscopy surgeons of this topic will lead to improved clinical outcomes after hip arthroscopy for a challenging cohort.

Outcomes After Management of Subspine and Femoroacetabular Impingement Using a Direct Anterior Mini-Open Approach

Background

Subspine impingement (SSI) has been commonly managed with arthroscopic decompression. However, arthroscopic decompression is a demanding technique, as under- or over-resection of the anterior inferior iliac spine (AIIS) could lead to inferior outcomes. An anterior mini-open approach has also been used in the management of femoroacetabular impingement (FAI), and it could provide adequate visualization of the anterior hip joint without a long learning curve.

Purpose/Hypothesis

The objective of the current study was to compare the outcomes of SSI patients with FAI who underwent arthroscopic subspine decompression and osteoplasty with a group undergoing subspine decompression and osteoplasty using a modified direct anterior mini-open approach. It was hypothesized that there would be no significant difference in outcomes between the groups.

Study Design

Cohort study; Level of evidence, 3.

Methods

We reviewed the records of SSI patients who underwent decompression surgery (arthroscopic or mini-open) at our institution from June 1, 2015 to December 31, 2016. Both groups underwent the same postoperative rehabilitation protocol. Preoperative and 2-year postoperative patient-reported outcomes were compared using the modified Harris Hip Score (mHHS), International Hip Outcome Tool-33 (iHOT-33), and Hip Outcome Score-Activities of Daily Living (HOS-ADL). Major and minor complications as well as reoperation rates were recorded.

Results

Included were 47 patients (49 hips) who underwent subspine decompression using an anterior mini-open approach and 35 patients (35 hips) who underwent arthroscopic subspine decompression. There were no differences in demographic and radiological parameters between the groups, and patients in both groups showed significant improvement in all outcome scores at follow-up. The pre- to postoperative improvement in outcome scores was also similar between groups (mini-open vs arthroscopy: mHHS, 26.30 vs 27.04 [P = .783]; iHOT-33, 35.76 vs 31.77 [P = .064]; HOS-ADL, 26.09 vs 22.77 [P = .146]). In the mini-open group, 10 of the 47 patients had temporary meralgia paresthetica, and fat liquefaction was found in 1 female patient. There were no reoperations in the mini-open group.

Conclusion

Subspine decompression using the anterior mini-open approach had similar outcomes to arthroscopic decompression in the management of SSI. The lateral femoral cutaneous nerve should be protected carefully during use of the anterior mini-open approach.

Subspine Hypertrophy: Higher Incidence of Symptomatic versus Asymptomatic Hips in Patients with Unilateral Femoroacetabular Impingement

Objective

To compare the difference of anterior inferior iliac spine (AIIS) and subspine hypertrophic deformity between symptomatic and asymptomatic hips in patients traditionally diagnosed with femoroacetabular impingement (FAI), and investigate the correlation of subspine decompression with AIIS variation and subspine hypertrophic deformity.

Methods

We retrospectively reviewed 70 patients with unilateral symptomatic FAI who underwent hip arthroscopy. The operative hips and contralateral hips naturally formed the symptomatic groups and asymptomatic control groups, respectively. The morphometric comparison of the hip joint was performed between the operative and contralateral sides of each patient. Radiological assessment was performed by two observers (an experienced musculoskeletal radiologist and an experienced surgeon). Three‐dimensional (3D)‐CT images of each patient were blindly reviewed to determine the AIIS variation and subspine hypertrophic deformity. Reformatted two‐dimensional (2D)‐CT images and anterior–posterior (AP) pelvic plain radiographs were blindly reviewed to determine FAI‐related morphological measurements. Moreover, the surgical assessment was reviewed by one experienced surgeon to interpret whether subspine decompression was performed. The correlation of subspine decompression with AIIS variation and subspine hypertrophy was analyzed.

Results

Out of 70 patients with unilateral symptomatic FAI, 37 were males (52.9%) and 23 (32.9%) had symptoms involving the left hip. The mean age was 39.3 ± 10.4 years and the mean BMI was 24.3 ± 3.6. The distribution of AIIS variants in symptomatic hips did not differ significantly from that in asymptomatic hips (χ² = 3.092, P = 0.213). Twenty‐nine hips in the symptomatic group (41.4%) and 12 hips in the asymptomatic group (17.1%) were identified as positive for subspine hypertrophy. The incidence of positive subspine hypertrophy was significantly higher in the symptomatic hips compared to the asymptomatic hips (χ² = 9.968, P = 0.002). FAI‐related morphological parameters including α angle, lateral center‐edge angle, acetabular anteversion, crossover sign, and Tonnis grade were highly symmetrical and did not show significant differences between symptomatic and asymptomatic hips. Fifty‐four of 70 hips (77.1%) had labral tears extended to the acetabular rim corresponding to the AIIS. Forty‐seven hips of 70 hips (67.1%) underwent subspine decompression, which was significantly correlated with AIIS variation and subspine hypertrophic deformity (P = 0.019 and 0.001, respectively).

Conclusion

Subspine hypertrophic deformity was found to be more common in symptomatic side vs asymptomatic side in patients with unilateral symptomatic femoroacetabular impingement. Subspine hypertrophy may be considered as an underlying indication for subspine decompression besides low‐lying AIIS.

Intraoperative Findings and Clinical Outcomes Associated With Arthroscopic Management of Subspine Impingement: A Propensity-Matched, Controlled Study

PURPOSE

(1) To investigate intra-articular damage in the hip joint associated with subspine impingement (SSI); (2) to evaluate clinical outcomes of arthroscopic treatment of hips with SSI; and (3) to compare the findings and outcomes to a control group without SSI.

METHODS

Eligible patients had arthroscopic treatment for femoroacetabular impingement (FAI) concurrent with SSI between January 2015 and December 2017. Inclusion criteria consisted of preoperative and minimum 2-year patient-reported outcomes and preoperative measurements for Tönnis, lateral center edge angle, and alpha angle. Included patients were propensity-matched in a 1:3 ratio to patients who had FAI without SSI. Patient-reported outcomes were compared between groups. Minimal clinically important difference was calculated for modified Harris Hip Score (mHHS) and Hip Outcome Score-Sports Specific Subscale (HOS-SSS).

RESULTS

Fifty SSI cases were matched to 150 patients who had FAI without SSI. A greater proportion of the SSI cohort required labral reconstruction (P = .010). The size and locations for labral tears and chondral defects were comparable between groups (P > .05). Both groups demonstrated similar minimum 2-year outcomes for mHHS (P = .103), Nonarthritic Hip Score (P = .200), HOS-SSS (P = .119), visual analog scale (P = .231), international Hip Outcome Tool-12 (P =.300), Short Form-12 Mental (P = .426), Short Form-12 Physical (P = .328), Veterans RAND 12-Item Health Survey, Mental (P = .419), and Veterans RAND 12-Item Health Survey, Physical (P = .316). The percentage of patients achieving minimal clinically important difference for mHHS and HOS-SSS was similar (P > .05). Survivorship was 96.0% and 98.7% for the SSI and control cohorts at 2 years, respectively.

CONCLUSIONS

Arthroscopic treatment of hips with SSI with subspine decompression and concomitant treatment of labral tears and FAI yielded significant improvement in patients' outcomes, which compared favorably with the control group. SSI may correlate with more complex labral tears, not amenable to repair, and complete tears of the ligamentum teres. Other findings, such as location and size of intra-articular damage, were similar between the cohorts.

LEVEL OF EVIDENCE

III, case-control study.

The case of 'A Rhino Horn': case report and proposal for modification to the Hetsroni and Kelly classification

Subspine impingement syndrome by definition involves a prominent antero-inferior iliac spine (AIIS) which can lead to impingement on the femoral neck thereby causing symptoms. We present the case of a 22-year-old semi-professional athlete who presented with a Type III AIIS morphology leading to subspine impingement syndrome and was managed via a mini open anterior approach. Radiological examination revealed a fairly prominent left AIIS resembling the 'horn of a rhino' extending to the trochanteric region anteriorly. A mini-anterior surgical approach was utilized for the resection of the 'rhino horn' and the rectus femoris was reattached. The patient remained asymptomatic at the one-year follow-up and had resumed weightlifting. Following this case, we propose a new classification of the type III AIIS morphology in view of the clinical presentation. The AIIS type III-Standard represents an extension from the acetabular rim to less than 1 cm (type III-S) and type III-Large, with an extension from the acetabular rim beyond 1 cm (type III-L). The type III-L will further be divided into two groups based on its relation to the ilium, type III-Lr ('rib shape') and type III-Lrh ('rhino horn').

Hip Arthroscopy for Femoroacetabular Impingement: Minimal Clinically Important Difference Rates Decline From 1- to 5-Year Outcomes

Purpose

To correlate patient-reported outcomes (PROs) and minimal clinically important difference (MCID) achievement rates after hip arthroscopy for femoroacetabular impingement syndrome (FAI).

Methods

Patients with clinically diagnosed FAI who underwent primary hip arthroscopy from September 2012 to March 2014 with a minimum of 5-year outcomes were identified. Patients undergoing labral debridement, microfracture, bilateral procedures, with evidence of dysplasia, Tönnis grade >1, and joint space <2 mm were excluded. Analysis of variance was used to compare PROs. Survival rates were determined using Kaplan–Meier analysis. Regression analysis identified associations with modified Harris Hip Scores (mHHS), minimal clinically important difference (MCID) rates, and Nonarthritic Hip Scores (NAHS).

Results

A total of 85 of 101 eligible consecutive patients (84% inclusion) (age: 41.4 ± 14.0 years; 69% female, mean body mass index [BMI] 25.0 ± 4.2) met inclusion and exclusion criteria. Patients underwent labral repair (100%) and a combination of cam (86%) and pincer resection (99%). The 5-year survival-to-revision rate was 77% whereas 5-year survival rate to total hip arthroplasty was 94%. The 1-year (87.4 ± 13.6) and 5-year (84.5 ± 13.5) mHHS scores were greater versus preoperative scores (46.3 ± 11.3, P < .001). There was a decrease in MCID rate between 1-year (n = 74, 87%) and 5-year (n = 61, 73%, P = .019) outcomes. The 1-year (87.4 ± 12.7) and 5-year (89.2 ± 15.8) NAHS scores were greater versus preoperative scores (49.7 ± 12.7, P < .001). Regression demonstrated associations between BMI (MCID: P = .033; NAHS: P = .010), age (mHHS: P = .031), and cam resection (mHHS: P = .010) with 5-year outcomes.

Conclusions

There is a decline in MCID at 5-year follow-up after hip arthroscopy for FAI. Lower BMI, younger age, and cam resection are associated with positive outcomes. There is excellent index procedure survivability and excellent total hip arthroplasty prevention rate.

Level of Evidence

Level IV.

Prominent Anterior Inferior Iliac Spine Morphologies Are Common in Patients with Acetabular Dysplasia Undergoing Periacetabular Osteotomy

BACKGROUND

The anterior inferior iliac spine (AIIS) prominence is increasingly recognized in the setting of femoroacetabular impingement (FAI). The AIIS prominence may contribute to decreased hip flexion after acetabular reorientation in patients with acetabular dysplasia. AIIS morphologies have been characterized in numerous populations including asymptomatic, FAI, and athletic populations, but the morphology of the AIIS in patients with symptomatic acetabular dysplasia undergoing periacetabular osteotomy (PAO) has not been studied. In acetabular dysplasia, deficiency of the anterosuperior acetabular rim is commonly present and may result in the AIIS being positioned closer to the acetabular rim. Understanding morphological variation of the AIIS in patients with symptomatic dysplasia, and its relationship to dysplasia subtype and severity may aid preoperative planning, surgical technique, and evaluation of postoperative issues after PAO.

QUESTIONS/PURPOSES

In this study, we sought to determine: (1) the variability of AIIS morphology types in hips with symptomatic acetabular dysplasia and (2) whether the differences in the proportion of AIIS morphologies are present between dysplasia pattern and severity subtypes.

METHODS

Using our hip preservation database, we identified 153 hips (148 patients) who underwent PAO from October 2013 to July 2015. Inclusion criteria for the current study were (lateral center-edge angle [LCEA] < 20°), Tönnis Grade of 0 or 1 on plain AP radiographs of the pelvis, preoperative low-dose CT scan, and no prior surgery, trauma, neuromuscular, ischemic necrosis, or Perthes-like deformity. A total of 50 patients (50 hips) with symptomatic acetabular dysplasia undergoing evaluation for surgical planning of PAO remained for retrospective evaluation; we used these patients' low-dose CT scans for analysis. The median (range) age of patients in the study was 24 years (13 to 49). Ninety percent (45 of 50) of the hips were in female patients, whereas 10% (5 of 50) were in male patients. The morphology of the AIIS was classified on three-dimensional CT reconstructions according to a previously published classification to define the relationship between the AIIS and the acetabular rim. The morphology of the AIIS was classified as Type I (AIIS well proximal to acetabular rim), Type II (AIIS extending to level of acetabular rim), or Type III (AIIS extending distal to acetabular rim). Acetabular dysplasia subtype was characterized according to a prior protocol as either predominantly an anterosuperior acetabular deficiency, a posterosuperior acetabular deficiency, or a global acetabular deficiency. Acetabular dysplasia severity was distinguished as mild (LCEA 15° to 20°) or moderate/severe (LCEA < 15°). To answer our first question, regarding the proportions of each AIIS morphology in the dysplasia population, we calculated proportions and 95% CI estimates. To answer our second question, regarding the proposition of AIIS type between subtypes of dysplasia type and severity, we used a chi-square test or Fisher's exact test to compare categorical variables. A p value of < 0.05 was considered significant.

RESULTS

Seventy-two percent (36 of 50; 95% CI 58% to 83%) of patients had a Type II or III AIIS morphology. Type I AIIS morphology was found in 28% of patients (14 of 50; 95% CI 18% to 42%), Type II AIIS morphology in 62% (31 of 50; 95% CI 48% to 74%), and Type III AIIS/morphology in 10% (5 of 50; 95% CI 4% to 21%). A Type I AIIS was seen in seven of 15 of patients with anterosuperior acetabular deficiency, three of 18 of patients with global deficiency, and four of 17 patients with posterosuperior deficiency (p = 0.08). There was no difference in the variability of AIIS morphologies between the different subtypes of acetabular dysplasia pattern and no difference in AIIS morphology variability between patients with mild versus moderate/severe dysplasia.

CONCLUSIONS

The morphology of the AIIS in patients with acetabular dysplasia is commonly prominent, with 72% of hips having Type II or Type III morphologies.

CLINICAL RELEVANCE

The AIIS is often prominent in patients with acetabular dysplasia undergoing PAO, regardless of dysplasia pattern or severity. Prominent AIIS morphologies may affect hip flexion ROM after acetabular reorientation. AIIS morphology is a variable that should be considered during preoperative planning for PAO. Future studies are needed to assess the clinical significance of a prominent AIIS on intraoperative findings and postoperative status after PAO.

Evaluation of anterior inferior iliac spine impingement after hip arthroscopic osteochondroplasty using computer simulation analysis

BACKGROUND

Anterior inferior iliac spine (AIIS) impingement is an important risk factor for revision hip arthroscopy. Although a morphological classification system is available, evaluating AIIS impingement with respect to joint kinematics remains a challenge.

PURPOSE

To use computer simulation analysis to ascertain the prevalence of AIIS impingement before and after osteochondroplasty.

METHODS

A total of 35 joints from 30 cases (20 males and 10 females; average age: 43.3 ± 13.7 years) were analyzed. All joints had cam morphology and underwent hip arthroscopic osteochondroplasty. A three-dimensional model of each joint was constructed pre- and postoperatively. Joint kinematic simulation software (ZedHip®, Lexi, Tokyo) was used to identify the impingement point on the acetabular side and the incidence (expressed as a percentage) of AIIS impingement calculated. Radiographic and clinical evaluation was performed pre- and postoperatively.

RESULTS

AIIS impingement was observed postoperatively in six joints but preoperatively in only one joint. The rate of AIIS postoperative impingement was significantly higher than that of preoperative impingement. All impingement points were located on the inferior aspect of the AIIS apex. However, there were no significant differences between the AIIS impingement and non-impingement groups in terms of clinical outcome.

CONCLUSION

The incidence of AIIS impingement after osteochondroplasty was 17% by computer simulation analysis. Osteochondroplasty may result in subsequent AIIS impingement.

Prevalence of Anterior Inferior Iliac Spine Dysmorphism and Development of a Novel Classification System: An Anatomic Study of 1,797 Cadaveric Specimens

Purpose: Subspine impingement occurs due to a morphologically abnormal anterior inferior iliac spine (AIIS), capable of causing impingement against the distal femoral neck. The purpose of this investigation was to determine the prevalence of AIIS dysmorphism based on specimen sex, race, and age, while introducing a novel anatomic-based classification system.

Methods: A total of 1,797 adult cadaveric specimens (n = 3,594 hemipelvises) were analyzed. AIIS with the potential for subspine impingement (SSI) was recorded in each specimen by two independent authors. Specimens with AIIS dysmorphism were then reexamined to determine SSI subtype using a novel descriptive anatomic classification system.

Results: AIIS dysmorphism was present in 6.4% (n = 115 of 1,797 specimens) of specimens and 5.2% (n = 186 of 3,594) of hemipelvises. Dysmorphism was significantly more common in male specimens (p = 0.04) and African–American specimens (p = 0.04). No significant overall difference in prevalence was appreciated based on specimen age (p = 0.89). Subtype classification found that 67% of hemipelvises possessed a columnar type AIIS, 30% were bulbous and 3% hook type. Males possessed a significantly higher prevalence of columnar type AIIS dysmorphism (p < 0.001). No significant overall differences in anatomic classification were appreciated based on race (p = 0.12) or when analyzed based on age (p = 0.34).

Conclusion: AIIS dysmorphism was present in 6.4% of the 1,797 cadaveric specimens evaluated. African-American and male specimens possessed significantly higher prevalence of AIIS dysmorphism, with no significant difference based on specimen age. Columnar type AIIS dysmorphism was most common. Anatomic classification was not significantly different based on specimen race or age.

Level of Evidence: Case Series, Level IV.

Hip Arthroscopy for Femoroacetabular Impingement: 1-Year Outcomes Predict 5-Year Outcomes

BACKGROUND

Limited evidence exists comparing short- and long-term patient-reported outcomes (PROs) and overall survival rates after hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

HYPOTHESIS

Patients with high improvement (HI) versus low improvement (LI) at 1 year postoperatively would achieve higher PROs and better index procedure survival rates at 5-year follow-up.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who underwent primary hip arthroscopy for FAIS between September 2012 and March 2014 with minimum 5-year outcome data were identified. Using the median 1-year change in modified Harris Hip Score (mHHS) as a threshold, HI and LI subcohorts were determined. Analysis of variance was used to compare PROs. Failure rates were determined using Kaplan-Meier and Cox proportional hazards model analyses. Regression analysis was used to identify factors associated with increasing 5-year change in mHHS and Nonarthritic Hip Score (NAHS).

RESULTS

Out of 108 eligible consecutive patients, 89 (82.4%) were included (mean [SD]: age, 43.3 [14.6] years; body mass index, 25.4 [4.5]). As compared with the LI group (n = 45), the HI group (n = 44) had a longer 5-year index surgery survival rate (mean ± SEM: 83.7 ± 3.3 months vs 68.5 ± 4.6 months; P = .012) and 5-year estimated survival rate (89% vs 71%). The HI group had a decreased risk of failure versus the LI group (hazard ratio, 0.15; P = .002). The HI group also had greater PROs than did the LI group at 1 year (mHHS: 94.8 ± 1.2 vs 72.6 ± 2.7, P < .001; NAHS: 94.0 ± 1.3 vs 75.6 ± 2.2, P < .001) and 5 years (mHHS: 86.9 ± 2.0 vs 77.6 ± 3.4, P = .017; NAHS: 92.6 ± 1.8 vs 82.7 ± 4.1, P = .020). As compared with the LI group, the HI group achieved higher rates of the Patient Acceptable Symptomatic State (PASS) and minimal clinically important difference (MCID) at 1 year (PASS: 95% vs 42%, P < .001; MCID: 100% vs 89%, P = .056) and 5 years (PASS: 77% vs 45%, P = .002; MCID: 86% vs 64%, P = .014). Linear regression demonstrated that being in the HI group (ΔmHHS, P = .041; ΔNAHS, P = .017) and decreasing body mass index (ΔmHHS, P = .055; ΔNAHS, P = .023) were associated with higher 5-year ΔPROs.

CONCLUSION

Patients with FAIS and significant improvement in the first year after hip arthroscopy had superior 5-year outcomes versus patients with persistent symptom severity. Survival rates and PROs were significantly better in patients who achieved high early outcomes at the 1-year mark.

Arthroscopic Management of Subspinous Impingement in Borderline Hip Dysplasia and Outcomes Compared With a Matched Cohort With Nondysplastic Femoroacetabular Impingement

BACKGROUND

Arthroscopic management of femoroacetabular impingement (FAI) in the setting of borderline hip dysplasia is controversial. Recently, there has been increased awareness of a prominent anterior inferior iliac spine (AIIS) resulting in subspinous impingement.

PURPOSE/HYPOTHESIS

The purpose was to report outcomes of arthroscopic subspinous decompression in patients with symptomatic hip impingement and borderline hip dysplasia compared with a matched cohort with nondysplastic FAI. Addressing a prominent subspinous region and cam/pincer lesion in the borderline dysplastic hip may lead to favorable outcomes comparable with those of patients undergoing arthroscopic management of nondysplastic FAI.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients with symptomatic hip impingement, borderline dysplasia (lateral center-edge angle [LCEA], 18°-24°), and prominent AIIS (BDSI group) whose nonoperative management failed and who subsequently underwent arthroscopic subspinous decompression were retrospectively identified. Three-dimensional computed tomography imaging was used to categorize AIIS morphology into type 1, 2, or 3 (Hetsroni classification). Patient-reported outcome (PRO) scores consisting of the modified Harris Hip Score (mHHS), Hip Outcome Score-Activities of Daily Living (HOS-ADL), and Hip Outcome Score-Sport-Specific Subscale (HOS-SSS) were obtained preoperatively and at an average of 44 months postoperatively (range, 23-61 months). Exclusion criteria were Tönnis osteoarthritis grade >1 and a history of previous hip procedures. An age-, sex-, and body mass index-matched cohort of patients without dysplasia (LCEA, >25°) who underwent arthroscopic FAI surgery with a minimum 2-year follow-up were selected to serve as the control group.

RESULTS

Eighteen patients, 19 hips (14 women and 4 men; average age, 28 years) were included. Of the 19 hips in the BDSI group, the average LCEA and alpha angle were 21.8° and 66.2°, respectively; 14 hips were Hestroni type 2, and 5 hips were type 1. There were no postoperative complications or additional procedures performed since the last follow-up. Repeated-measures analysis of variance revealed a significant improvement in all PRO scores from preoperatively to the last follow-up: mHHS, 64.7 to 87.7 (P < .001); HOS-ADL, 62.1 to 92.1 (P < .001); HOS-SSS, 26.5 to 87.1 (P < .001). An analysis of covariance revealed that patients with type 2 AIIS had a significantly higher postoperative mHHS than those with a type 1 morphology (88.3 and 95.6, respectively; P < .01) The BDSI group had a significantly lower preoperative HOS-SSS (26.5; P < .001) in comparison with the control group. However, there was no significant difference in postoperative outcome scores between groups. The BDSI group underwent significantly more microfracture, capsular plication, and ligamentum teres debridement (15.8%; P = .04).

CONCLUSION

Arthroscopic AIIS decompression in patients with coexisting borderline dysplasia and subspinous impingement is a safe and effective method of treatment that produces outcomes comparable with those of a cohort with nondysplastic FAI.

Subspine Hip Impingement: Clinical and Radiographic Results of its Arthroscopic Treatment

Objective  To evaluate the clinical and radiographic results as well as complications related to patients undergoing arthroscopic treatment of subspine hip impingement.

Methods  We retrospectively evaluated 25 patients (28 hips) who underwent arthroscopic treatment of subspine impingement between January 2012 and June 2018. The mean follow-up was 29.5 months, and the patients were evaluated clinically by using the Harris hip score modified by Byrd (MHHS), the non-arthritic hip score (NAHS), and in terms of internal rotation and hip flexion. In addition, the following items were evaluated by imaging exams: the center-edge (CE) acetabular angle, the Alpha angle, the presence of a sign of the posterior wall, the degree of arthrosis, the presence of heterotopic hip ossification, and the Hetsroni classification for subspine impingement.

Results  There was an average postoperative increase of 26.9 points for the MHHS, 25.4 for the NAHS ( p  < 0.0001), 10.5° in internal rotation ( p  < 0.0024), and 7.9° for hip flexion ( p  < 0.0001). As for the radiographic evaluation, an average reduction of 3.3° in the CE angle and of 31.6° for the Alpha angle ( p  < 0.0001). Eighteen cases (64.3%) were classified as grade 0 osteoarthritis of Tönnis, and 10 (35.7%) were classified as Tönnis grade 1. Two cases (7.1%) presented grade 1 ossification of Brooker. Most hips ( n  = 15, 53.6%) were classified as type II of Hetsroni et al.

Conclusion  In the present study, patients undergoing arthroscopic treatment with subspine impingement showed improvement in clinical aspects and radiographic patterns measured postoperatively, with an average follow-up of 29.5 months.

Arthroscopic anterior inferior iliac spine decompression does not alter postoperative muscle strength

PURPOSE

The purpose of this study was to assess the additional effect of anterior inferior iliac spine (AIIS) decompression on knee extensor and hip flexor strength and compare functional outcomes after arthroscopic FAI correction with and without AIIS decompression.

METHODS

Sixty patients who underwent arthroscopic FAI correction surgery were divided into two groups matched for AIIS morphology: 31 patients who underwent arthroscopic FAI surgery only (without AIIS decompression) (FAI group) (AIIS Type I; n = 5, Type II; n = 26, Type III; n = 0) and 29 patients who underwent arthroscopic FAI surgery with AIIS decompression (AIIS group) (AIIS Type I; n = 5, Type II; n = 24, Type III; n = 0). Knee extensor and hip flexor strength were evaluated preoperatively and at 6 months after surgery. Patient-reported outcome (PRO) scores using the modified Harris hip score (MHHS), the nonarthritic hip score (NAHS) and iHOT-12 were obtained preoperatively and at 6 months after surgery.

RESULTS

In the AIIS group, there was no significant difference between knee extensor strength pre- and postoperatively (n.s.). In the AIIS group, hip flexor strength was significantly improved postoperatively compared to preoperative measures (p < 0.05). In the FAI group, there were no significant improvements regarding muscle strength (n.s.). While there were no significant differences of preoperative and postoperative MHHS and NAHS between both groups (MHHS; n.s., NAHS; n.s.), the mean postoperative iHOT-12 in the FAI group was inferior to that in the AIIS group. (p < 0.01). The revision surgery rate for the AIIS group was significantly lower compared with that in the FAI group (p < 0.05).

CONCLUSION

Anterior inferior iliac spine decompression, as a part of an arthroscopic FAI corrective procedure, had a lower revision surgery rate and did not compromise knee extensor and hip flexor strength, and it improved clinical outcomes comparable to FAI correction without AIIS decompression. AIIS decompression for FAI correction improved postoperative PRO scores without altering the muscle strength of hip flexor and knee extensor.

LEVEL OF EVIDENCE

III.

Functional Results of Arthroscopic Treatment in Patients With Femoroacetabular and Subspine Impingement Diagnosed With a 3-Dimensional Dynamic Study

Purpose

To describe the functional results of arthroscopic treatment in patients with femoroacetabular impingement (FAI) and subspine impingement (SSI) evaluated with a 3-dimensional (3D) dynamic study.

Methods

This was a retrospective observational study of patients with a diagnosis of FAI and SSI, evaluated with a 3D dynamic computed tomography scan with Move Forward software, who underwent hip arthroscopy between February 2015 and December 2017. Measurements of the alpha angle, femoral anteversion, acetabular anteversion, lateral center-edge angle, and Tönnis angle were extracted from the 3D dynamic study. Functionality was evaluated using the Western Ontario McMaster Universities Osteoarthritis Index before and 12 months after surgery.

Results

We analyzed 22 hips in 17 patients (9 female and 8 male patients) with an average age of 34.6 ± 14.3 years. Of the 22 hips, 15 had cam morphology, 6 had mixed morphology, and 1 had pincer morphology. Of the hips, 11 had a type I spine, 10 had type II, and 1 had type III. The average alpha angle, Tönnis angle, femoral anteversion, and acetabular anteversion were 61.9° ± 11.1°, 2.5° ± 6.4°, 8.8° ± 6.8°, and 15.1° ± 7.1°, respectively. The median lateral center-edge angle was 38.1° (interquartile range, 32.6°-43.5°). At 1-year follow-up, a decrease in the Western Ontario McMaster Universities Osteoarthritis Index score (P = .001) and an increase in the flexion angle (P < .001) were observed. No cases needed posterior surgical revision because of persistent pain.

Conclusions

Arthroscopic treatment provides symptom relief and good functional results in patients with FAI and SSI.

Level of Evidence

Level IV, therapeutic case series.

MRI Assessment of Subspine Impingement: Features beyond the Anterior Inferior Iliac Spine Morphology

Background The MRI manifestations of subspine impingement (SSI) other than morphologic features of anterior inferior iliac spine (AIIS) have not been extensively explored and validated. Purpose To determine the MRI findings associated with SSI, including AIIS morphologic features, femoral distal cam, and associated soft-tissue injuries. Materials and Methods This is a retrospective study of symptomatic patients who underwent arthroscopic treatment for femoroacetabular impingement between December 2014 and March 2017, with preoperative MRI within 6 months before surgery. The SSI group included patients with clinical and intraoperative findings of SSI; the remaining patients comprised the non-SSI group. Preoperative MRI findings were independently assessed by two radiologists who were blinded to clinical information. Interreader agreement was assessed, and multivariable logistic regression was also used. Results A total of 62 patients (mean age ± standard deviation, 42.1 years ± 11.9; 38 women) were included. SSI was diagnosed in 20 of the 62 patients (32%) (mean age, 43 years ± 12); 42 patients (68%) did not have SSI (mean age, 41 years ± 10). Reader 1 detected distal cam in 16 of the 20 patients with SSI (80%) and eight of the 42 patients without SSI (19%), and reader 2 detected distal cam in 15 of the 20 patients with SSI (75%) and eight of the 42 patients without SSI (19%) (P < .001 for both). Reader 1 detected signs of impingement on the distal femoral neck (IDFN) in 18 of the 20 patients with SSI (90%) and seven of the 42 patients without SSI (16%), and reader 2 detected signs of IDFN in 13 of the 20 patients with SSI (65%) and nine of the 42 patients without SSI (21%) (P < .001 and P = .001, respectively). Reader 1 detected superior capsular edema in 15 of 20 patients with SSI (75%) and three of 42 patients without SSI (7%), and reader 2 detected superior capsular edema in 17 of 20 patients with SSI (85%) and 22 of 42 patients without SSI (52%) (P < .001 and P = .02, respectively). Distal cam was a predictor of SSI after adjustment for IDFN. Interreader agreement was substantial for distal cam (κ = 0.80) and moderate for IDFN (κ = 0.50). Conclusion Soft-tissue injuries and osseous findings other than morphologic features of the anterior inferior iliac spine were associated with subspine impingement. © RSNA, 2019 See also the editorial by Guermazi in this issue.

Extra-articular hip impingement: clinical presentation, radiographic findings and surgical treatment outcomes

Femoroacetabular impingement syndrome is classically thought of as either a cam or pincer deformity causing abnormal bony contact resulting in labral pathology. However, alternate patterns of hip impingement can occur, but tend to be less commonly recognized or studied. Collectively termed 'extra-articular impingement', four subgroups of impingement can contribute to non-arthritic hip pain and disability: iliopsoas impingement, subspine impingement, ischiofemoral impingement and trochanteric-pelvic impingement. The purpose of this review article is to highlight the pertinent points to aid in proper clinical and radiographic evaluation to allow appropriate diagnosis. Additionally, a review of potential surgical treatment options and resultant outcomes will also be provided.

Editorial Commentary: PASSing the Test Versus Acing It: Understanding Clinically Significant Outcome Improvement in Arthroscopic Hip Surgery

There is increasing interest in defining clinically significant outcome after orthopaedic procedures, and the field of hip preservation surgery is leading the way. Minimal clinically important difference, patient acceptable symptomatic state (PASS), and substantial clinical benefit have been established as important measures of clinically significant outcome. The International Hip Outcome Tool 12-question subset, one of the newer hip-specific measures, is being increasingly used. The 12-item version may prove popular among investigators given its decreased questionnaire burden. There still remain opportunities in future work to standardize how we analyze, interpret, and report clinically significant outcome. Specifically, an anchor-based method for calculating PASS may provide a more accurate representation of PASS score for arthroscopic hip surgery patients.

Prevalence of Generalized Ligamentous Laxity in Patients Undergoing Hip Arthroscopy: A Prospective Study of Patients' Clinical Presentation, Physical Examination, Intraoperative Findings, and Surgical Procedures

BACKGROUND

Recent studies identified microinstability in the hip as a pathoetiology of painful hip conditions, and it was proposed that generalized ligamentous laxity conditions may predispose patients to such microinstability.

PURPOSE

To study the relationship of generalized ligamentous laxity with patient characteristics, clinical presentation, intraoperative findings, and surgical treatments in a cohort of patients undergoing hip arthroscopy.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Registry data were prospectively collected and retrospectively reviewed between February 2014 and November 2017 for patients who underwent primary hip arthroscopy and had a documented Beighton score to assess generalized ligamentous laxity. Patients with a history of an ipsilateral hip condition or ipsilateral hip surgery, those with Tönnis grade >1, and those who had simultaneous arthroscopic and open procedures were excluded from the study. Two comparisons were made between patients with low and high Beighton scores: Beighton 0 vs ≥1 (B 0 vs B ≥1) and Beighton 0-3 vs ≥4 (B 0-3 vs B ≥4). Patient demographics, symptomatology, physical examination, and intraoperative findings were compared between these low and high Beighton groups.

RESULTS

A total of 1381 patients met our inclusion and exclusion criteria. Within this patient population, there were 882 with B 0, 499 with B ≥1, 1120 with B 0-3, and 261 with B ≥4. B 0 was 54.1% female, compared with 84.2% of B ≥1. Similarly, B 0-3 was 58.5% female, while B ≥4 was 92.7% female. The difference in sex makeup was significant between both sets of groups ( P < .0001). The relative risk of having B ≥1 for women versus men was 2.869, and the relative risk of having B ≥4 for women versus men was 6.873. The patients with higher Beighton scores in B ≥1 and B ≥4 had a younger mean age at onset of symptoms ( P < .0001) and lower mean body mass index ( P < .0001) than those in B 0 and B 0-3, respectively. The B ≥1 group had higher preoperative range of motion with internal rotation ( P = .05), external rotation ( P = .017), and flexion ( P < .0001) than B 0 patients, as well as a lower frequency of Trendelenburg gait pattern ( P = .0268). Similarly, the B ≥4 group had higher range of motion than the B 0-3 group with internal rotation ( P = .030), external rotation ( P = .003), flexion ( P < .0001), and abduction ( P = .002). As compared with the lower-score groups, the higher-score groups also had smaller labral size and tear dimension ( P < .0001), and a higher proportion of these patients underwent labral repair, capsular repair, and iliopsoas fractional lengthening.

CONCLUSION

Patients undergoing hip arthroscopy who have generalized ligamentous laxity are overall younger, have a lower body mass index, and are more often female, as compared with patients who have lesser laxity. Patients with higher preoperative Beighton scores had greater hip range of motion and smaller intraoperative labral size and tear dimensions. Additionally, these patients were more likely to undergo labral repair, capsular plication, and iliopsoas fractional lengthening.

Clinical outcomes and causes of arthroscopic hip revision surgery

Hip arthroscopic surgery has become a common technique during the past decade, leading to an increased number of arthroscopic hip revision surgeries. This study aimed to evaluate the clinical outcomes in a series of revision hip arthroscopies to analyse the causes of reoperation in the short to medium-term follow-up. We retrospectively analysed 22 patients who underwent arthroscopic hip revision surgery in our institute. All patients accepted a detailed physical examination and obtained radiographs to measure the centre edge angle, the alpha angle and the offset. Three-dimensional computed tomography was used to evaluate the deformities. The modified Harris Hip Score, visual analogue scale and patient self-reported satisfaction were collected and analysed preoperatively and postoperatively. Our results demonstrated that the modified Harris Hip Score improved from 52.8 to 81.6, and the visual analogue scale decreased from 5.0 to 1.1. Patient self-reported satisfaction was 8.5. In conclusion, patients who underwent arthroscopic hip revision surgery exhibited significant improvement in patient-centred outcomes in the short- to medium-term follow-up, and the outcomes indicated the effectiveness of revision surgery. Residual femoroacetabular impingement and extra-articular impingement are common reasons for arthroscopic hip revision surgery. Misdiagnosis of osteoid osteoma and relapse of synovial chondromatosis are also important reasons for revision.

Editorial Commentary: Subspine Hip Abnormalities: Exploring the Difference Between "Morphology" and "Impingement"

Subspine impingement has been increasingly recognized as a source of hip pain over the past 5 to 10 years. Some surgeons routinely perform subspine/anterior inferior iliac spine (AIIS) decompressions, whereas others rarely perform these procedures as part of an arthroscopic hip procedure. Subspine impingement has been implicated with high range-of-motion activities, various AIIS morphologies and deformities, and in the setting of persistent anterior hip pain after intra-articular anesthetic injections. Dynamic computed tomographic imaging has recently shown subspine impingement even with relatively normal AIIS morphology and in the setting of decreased femoral anteversion. These findings further emphasize the importance of understanding and defining relationships between morphology and impingement. Ultimately, subspine decompressions might be critical to achieve the best possible outcome after arthroscopic hip procedures in a subset of patients, but making the diagnosis remains challenging for clinicians.

Anterior Inferior Iliac Spine Morphology: Comparison of Symptomatic Hips With Femoroacetabular Impingement and Asymptomatic Hips

OBJECTIVE

The objective of our study was to compare anterior inferior iliac spine (AIIS) morphology in symptomatic hips with femoroacetabular impingement (FAI) and in asymptomatic hips, determine the prevalence of impingement morphology in patients with a radiographic "crossover" sign, and identify potential risk factors for having impingement morphology.

MATERIALS AND METHODS

For this retrospective study, we identified consecutive symptomatic hips with FAI (n = 54) and asymptomatic hips (n = 35) in patients who underwent CT from 2015 to 2017. Two radiologists blindly and independently evaluated 3D CT images of each hip and graded the AIIS morphology according to the Hetsroni classification scheme. The prevalence of AIIS morphology types was calculated. Associations of AIIS morphology types with symptoms and the crossover sign were evaluated with a chi-square test. A multivariable logistic regression determined risk factors for abnormal AIIS morphology (i.e., type 2 or 3).

RESULTS

There was no difference in the prevalence of AIIS morphology types for symptomatic hips with FAI versus asymptomatic hips (p = 0.44) or for hips with a positive versus those with a negative crossover sign (p = 0.21). There was moderate interobserver agreement (κ = 0.44) and good-to-excellent intraobserver agreement (κ = 0.67 and 0.90) for grading AIIS morphology. Age, sex, femoral version, acetabular version, alpha angle, lateral center edge angle, and the crossover sign were not significant risk factors for abnormal AIIS morphology in patients with FAI (p = 0.11-0.79).

CONCLUSION

There is no difference in AIIS morphology between symptomatic hips with FAI versus asymptomatic hips or between hips with and those without the radiographic crossover sign. Age, sex, and other FAI parameters are not risk factors for developing AIIS impingement morphology.

Arthroscopic Treatment of Acetabular Retroversion With Acetabuloplasty and Subspine Decompression: A Matched Comparison With Patients Undergoing Arthroscopic Treatment for Focal Pincer-Type Femoroacetabular Impingement

Background

Global acetabular retroversion is classically treated with open reverse periacetabular osteotomy. Given the low morbidity and recent success associated with the arthroscopic treatment of femoroacetabular impingement (FAI), there may also be a role for arthroscopic treatment of acetabular retroversion. However, the safety and outcomes after hip arthroscopic surgery for retroversion need further study, and the effect of impingement from the anterior inferior iliac spine (subspine) in patients with retroversion is currently unknown.

Hypothesis

Arthroscopic treatment for global acetabular retroversion will be safe, and patients will have similar outcomes compared with a matched group undergoing arthroscopic treatment for focal pincer-type FAI.

Study Design

Cohort study; Level of evidence, 2.

Methods

Patients undergoing hip arthroscopic surgery for symptomatic global acetabular retroversion were prospectively enrolled and compared with a matched group of patients undergoing arthroscopic surgery for focal pincer-type FAI. Both groups underwent the same arthroscopic treatment protocol. All patients were administered patient-reported outcome (PRO) measures, including the 12-item Short-Form Health Survey (SF-12) Physical Component Summary (PCS) and a Mental Component Summary (MCS), modified Harris Hip Score (mHHS), Hip disability and Osteoarthritis Outcome Score (HOOS), and visual analog scale (VAS) for pain preoperatively and at 1 year postoperatively.

Results

There were no differences in age, sex, or body mass index between 39 hips treated for global acetabular retroversion and 39 hips treated for focal pincer-type FAI. There were no major or minor complications in either group. Patients who underwent arthroscopic treatment for global acetabular retroversion demonstrated similar significant improvements in postoperative PRO scores (scores increased by 17 to 43 points) as patients who underwent arthroscopic treatment for focal pincer-type FAI. Patients treated for retroversion who also underwent subspine decompression had greater improvement than patients who did not undergo subspine decompression for the HOOS-Pain (33.7 ± 15.3 vs 22.5 ± 17.6, respectively; P = .046) and HOOS-Quality of Life (49.7 ± 18.8 vs 34.6 ± 22.0, respectively; P = .030) scores.

Conclusion

Arthroscopic treatment for acetabular retroversion is safe and provides significant clinical improvement similar to arthroscopic treatment for pincer-type FAI. Patients with acetabular retroversion who also underwent arthroscopic subspine decompression demonstrated greater improvements in pain and quality of life outcomes than those who underwent arthroscopic treatment without subspine decompression.

Preoperative Use of a 3D Printed Model for Femoroacetabular Impingement Surgery and Its Effect on Planned Osteoplasty

OBJECTIVE

The purpose of this study was to determine the effect that preoperative use of 3D printed models has on planned osteoplasty for femoroacetabular impingement (FAI) surgery.

MATERIALS AND METHODS

This experimental study utilizing retrospective data included 10 consecutive patients from July 1, 2013, to January 1, 2015, with a clinical diagnosis of FAI and imaging consisting of radiographs, CT scans, and MR images. Three-dimensional models of each patient's affected hip were printed to scale from CT data. Two orthopedic surgeons evaluated each patient in a routine preoperative manner. The effect of the 3D models in altering the planned osteoplasty was then determined. Proportions of osteoplasty change were calculated at various positions, and categoric variables were assessed with the chi-square test for independence.

RESULTS

Proportions of osteoplasty changes ranged from 20% to 55% at femoral positions (greatest at lateral and depth positions) and 35-75% at acetabular positions (greatest at anterior and depth positions). More osteoplasty changes occurred in patients with alpha angles of 60° or more (p = 0.00030) and without a radiographic crossover sign (p = 0.0075). We found no difference in the proportion of osteoplasty changes when stratifying by lateral center edge angle and coxa profunda (p = 0.190 and 0.109, respectively). The planned osteoplasty was changed for at least one reader in 9/10 (90%) femurs and 10/10 (100%) acetabula.

CONCLUSION

Use of 3D models in preoperative planning can change both the extent and location of planned osteoplasty for FAI surgery and is particularly influential in patients with alpha angles of 60° or more and without a radiographic crossover.