A review of imaging modalities for the hip

Spinopelvic Parameters Do Not Influence Outcomes Following Primary Hip Arthroscopy for the Treatment of Femoroacetabular Impingement Syndrome

Purpose

To evaluate the influence of spinopelvic parameters on short-term postoperative patient-reported outcomes (PROs) following primary hip arthroscopy for the treatment of femoroacetabular impingement syndrome (FAIS).

Methods

Patients undergoing primary hip arthroscopy between January 2012 and December 2015 were retrospectively reviewed. Hip Outcome Score - Activities of Daily Living, Hip Outcome Score - Sports-Specific Subscale, modified Harris Hip Score, International Hip Outcome Tool-12, and visual analog scale pain were recorded preoperatively and at final follow-up. Lumbar lordosis (LL), pelvic tilt (PT), sacral slope, and pelvic incidence (PI) were measured on lateral radiographs in standing position. Patients were split into subgroups for individual analyses based on previous literature cutoffs: |PI-LL|> or <10°, PT> or <20°, and PI <40°, 40° < PI < 65°, and PI >65°. PROs and rate of achievement of patient acceptable symptom state (PASS) were compared between subgroups at final follow-up.

Results

Sixty-one patients who underwent unilateral hip arthroscopy were included in the analysis, and 66% of patients were female. Mean patient age was 37.6 ± 11.3 years, whereas mean body mass index was 25.0 ± 5.7. Mean follow-up time was 27.6 ± 9.0 months. No significant difference in preoperative nor postoperative PROs were appreciated in patients with spinopelvic mismatch (|PI-LL| >10°) versus those without, whereas patients with mismatch achieved PASS according to the modified Harris Hip Score (P = .037) and International Hip Outcome Tool-12 (P = .030) at greater rates. When we compared patients with a PT ≥20° versus PT <20°, no significant differences in postoperative PROs were present. When we compared patients in the following pelvic incidence groups: PI <40°, 40° < PI <65°, and PI >65°, no significant differences in 2-year PROs or rates of PASS achievement for any PRO were appreciated (P > .05 for all).

Conclusions

In this study, spinopelvic parameters and traditional measures of sagittal imbalance did not influence PROs in patients undergoing primary hip arthroscopy for FAIS. Patients with sagittal imbalance (|PI-LL|> 10° or PT >20°) achieved a greater rate of PASS.

Level of Evidence

IV; Prognostic case series.

LibHip: An open-access hip joint model repository suitable for finite element method simulation

BACKGROUND AND OBJECTIVE

population-based finite element analysis of hip joints allows us to understand the effect of inter-subject variability on simulation results. Developing large subject-specific population models is challenging and requires extensive manual effort. Thus, the anatomical representations are often subjected to simplification. The discretized geometries do not guarantee conformity in shared interfaces, leading to complications in setting up simulations. Additionally, these models are not openly accessible, challenging reproducibility. Our work provides multiple subject-specific hip joint finite element models and a novel semi-automated modeling workflow.

METHODS

we reconstruct 11 healthy subject-specific models, including the sacrum, the paired pelvic bones, the paired proximal femurs, the paired hip joints, the paired sacroiliac joints, and the pubic symphysis. The bones are derived from CT scans, and the cartilages are generated from the bone geometries. We generate the whole complex's volume mesh with conforming interfaces. Our models are evaluated using both mesh quality metrics and simulation experiments.

RESULTS

the geometry of all the models are inspected by our clinical expert and show high-quality discretization with accurate geometries. The simulations produce smooth stress patterns, and the variance among the subjects highlights the effect of inter-subject variability and asymmetry in the predicted results.

CONCLUSIONS

our work is one of the largest model repositories with respect to the number of subjects and regions of interest in the hip joint area. Our detailed research data, including the clinical images, the segmentation label maps, the finite element models, and software tools, are openly accessible on GitHub and the link is provided in Moshfeghifar et al.(2022)[1]. Our aim is to empower clinical researchers to have free access to verified and reproducible models. In future work, we aim to add additional structures to our models.

Anthropometric measurements of the pediatric hip using CT-based simulated anteroposterior radiographs of the pelvis

Normal anatomical variants and pathological deformities of the pediatric hip can only be differentiated after a prior definition of normal ranges for anthropometric parameters with increasing age. Aim of the present study was to provide reliable reference values of the pediatric hip morphometry, using computed tomography (CT)-based rotation-corrected summation images of the pelvis that simulate the widely available plain radiograph-based measurements, but offer the higher precision of the CT technique. This retrospective study included 85 patients (170 hips) under 15 years of age (0-15). The measured anthropometric parameters included femur head extrusion index, lateral center-edge angle, acetabular inclination, Tönnis angle, and femoral neck-shaft angle. Mean values, range, SD, P values, intra-rater, and inter-rater reliability were calculated. All measurements correlated with age. None of the measurements correlated with gender or side. Rapid growth phases were noted in all measurements at the age of 12 (14 in males and 11 in females). The inter-rater and intra-rater reliability was high (range inter/intraclass correlation coefficient 0.926-0.998 Cronbach's alpha 0.986-0.998). The present work provides age- and gender-related normative values of the classically used hip measurements as well as growth phases describing pediatric hip morphology in a broad age range. A discrepancy was noted between the values measured in the current study and the classical X-ray-based reference values in the literature especially for the Tönnis angle and LCEA values. This suggests that the rotation and inclination correction in the CT-based techniques might have the advantage of compensating for a possible overestimation in the conventional X-ray-based methods.

Prolonged Postoperative Opioid Use After Arthroscopic Femoroacetabular Impingement Syndrome Surgery: Predictors and Outcomes at Minimum 2-Year Follow-up

Background:

The association between prolonged postoperative opioid use on outcomes after hip preservation surgery is not known.

Purpose:

To compare minimum 2-year patient-reported outcomes (PROs) between patients who required ≥1 postoperative opioid refill after undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS) versus patients who did not require a refill and to identify preoperative predictors for patients requiring ≥1 postoperative opioid refill.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Data from consecutive patients who underwent arthroscopic surgery for FAIS between January 2012 and January 2017 were analyzed. Multivariate regression analysis was performed to classify patient and radiographic variables as predictive of requiring ≥1 opioid prescription refill after surgery. Patients completed the following PROs preoperatively and at 2-year follow-up: Hip Outcome Score— Activities of Daily Living subscale (HOS-ADL), HOS–Sports Subscale (HOS-SS), modified Harris Hip Score (mHHS), International Hip Outcome Tool (iHOT-12), and 100-point visual analog scale (VAS) for pain and satisfaction. Scores were compared between patients needing additional prescription opioids and those who did not.

Results:

A total of 775 patients, of whom 141 (18.2%) required ≥1 opioid prescription refill, were included in the analysis. Patients requiring opioid refills had significantly lower 2-year postoperative PRO scores compared with patients not requiring refills: HOS-ADL (79.9 ± 20.3 vs 88.7 ± 14.9), HOS-SS (64.6 ± 29.5 vs 78.2 ± 23.7), mHHS (74.2 ± 21.1 vs 83.6 ± 15.9), iHOT-12 (63.6 ± 27.9 vs 74.9 ± 24.8), and VAS satisfaction (73.4 ± 30.3 vs 82.2 ± 24.9), as well as significantly more pain (26.8 ± 23.4 vs 17.9 ± 21.8) (P ≤ .001 for all). Predictors of requiring a postoperative opioid refill included patients with active preoperative opioid use (odds ratio, 3.12 [95% confidence interval, 1.06-9.21]; P = .039) and larger preoperative alpha angles (odds ratio, 1.04 [95% confidence interval, 1.01-1.07]; P = .03).

Conclusion:

Patients requiring ≥1 opioid prescription refill after hip arthroscopy for FAIS had lower preoperative and 2-year PRO scores when compared with patients not requiring refills. Additionally, active opioid use at the time of surgery was found to be predictive of requiring additional opioids for pain management.

Repeat Revision Hip Arthroscopy Outcomes Match That of Initial Revision But Not That of Primary Surgery for Femoroacetabular Impingement Syndrome

PURPOSE

To (1) report on pre- and postoperative patient-reported outcome (PRO) scores for patients undergoing repeat revision surgery in short-term follow-up and (2) compare minimal clinically important difference (MCID) and patient acceptable symptomatic state achievement between primary, revision, and repeat revision hip arthroscopy cohorts.

METHODS

Data from consecutive patients undergoing revision hip arthroscopy from January 2012 to February 2019 were retrospectively reviewed. Hips that underwent 2 revision hip arthroscopic surgeries were identified and matched 1:3 to patients undergoing revision surgery and 1:3 to patients undergoing primary surgery by age, sex, and body mass index. Baseline demographic data, surgical indications, and hip-specific PROs were collected were obtained preoperatively and at minimum 1-year follow-up. MCID was calculated individually for each cohort.

RESULTS

Twenty patients who underwent repeat revision were matched to 60 patients who underwent revision and 60 primary patients. Patients who underwent repeat revision achieved MCID on all investigated PROs at a similar rate to patients undergoing primary surgery (90.0% vs 91.7%, P = .588) and at a greater rate than patients undergoing first-time revision surgery (90.0% vs 71.7%, P = .045). Patients who underwent repeat revision achieved patient acceptable symptomatic state on all investigated PROs at a similar rate to patients who underwent first-time revision (30.0% vs 55.0%, P = .053) but at a significantly lower rate than primary patients (30.0% vs 76.7%, P < .001). However, patients undergoing repeat revision surgery had significantly lower preoperative PROs (P < .001 for all) and no significant difference in PROs at minimum 1-year follow-up compared with patients undergoing revision (P > .05). Compared with the primary cohort, patients who underwent repeat revision had significantly lower Hip Outcome Score-Activities of Daily Living (77.3 ± 16.7 vs 86.1 ± 14.4; P = .034), Hip Outcome Score-Sports Subscale (60.6 ± 27.2 vs 76.1 ± 23.8; P < .001), and modified Harris Hip Score (69.2 ± 19.3 vs 81.7 ± 16.1; P = .048) at a minimum of 1-year follow-up.

CONCLUSIONS

Second-time revision hip arthroscopy, which often requires advanced procedures, results in clinically significant improvement in PROs; however, outcomes for repeat revision cases are similar to first-time revision cases but inferior to those obtained following primary surgeries.

LEVEL OF EVIDENCE

Level III, retrospective case-control study.

Anthropometry of the proximal femur and femoral head in children/adolescents using three-dimensional computed tomography-based measurements

Purpose

Defining normal anthropometric ranges of proximal femur and femoral head for each age group in children/adolescents is a necessity when differentiating normal anatomical variants from pathological deformities. Aim of this study is to define a set of normal anthropometric parameters based on 3D-CT measurements in normal asymptomatic children/adolescents and analyse the variations arising depending on age, side, and/or gender.

Methods

Morphology of the proximal femur was retrospectively assessed in 170 hips (85 children, < 15 years). Measurements included covered femoral head volume (CFHV), femoral head diameter (FHD), femoral head extrusion index (FHEI), coronal alpha angle (CAA), lateral centre-edge angle (LCEA), anterior (AOS) and posterior head-neck offset (POS) and femoral neck-shaft angle (FNSA). Correlation analyses as well as inter- and intra-rater reliability were performed.

Results

CFHV, LCEA, FHD and AOS/POS increased with age and FHEI, CAA, and FNSA decreased with age. None of the measurements correlated with the side. AOS showed a poor correlation with gender. Rapid growth phases were observed at the age of 1, 7 and 11. The inter- and intra-rater reliability was high (range ICC 0.8–0.99 Cronbach alpha 0.86–0.99).

Conclusion

This data delivers a description of growth phases as well as gender and age-correlated reference values of the proximal femoral morphology that could be used by paediatricians and orthopaedic/paediatric surgeons to early diagnose proximal femur deformities and provide guidance in the planning of possible operations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00276-021-02841-3.

The Natural Course of Recovery After Hip Arthroscopy for Femoroacetabular Impingement According to the International Hip Outcome Tool-12 and Hip Outcome Score Sports Subscale

BACKGROUND

A paucity of literature exists regarding trajectories of functional and sports-specific recovery after hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

PURPOSE

To determine if subgroups of patients exist based on the recovery trajectory of patient-reported outcomes (PROs) after hip arthroscopy for FAIS in the short-term period and to determine clinical predictors for these subgroups of patients.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A prospectively maintained repository was queried for patients who had undergone primary hip arthroscopy for the treatment of FAIS between January 2012 and May 2018. Patients who completed the preoperative, 1-year, and 2-year International Hip Outcome Tool-12 (iHOT-12) or the Hip Outcome Score Sports Subscale (HOS-SS) were included. The latent class growth analysis (LCGA) and growth mixture models (GMMs) were used to identify subgroups of patients based on trajectories of recovery for the iHOT-12 and the HOS-SS utilizing preoperative, 1-year, and 2-year follow-ups. LCGA and GMM models using 1 to 6 classes for each PRO were performed, and the best-fit model for each PRO was selected. After final model selection, a multivariable multinomial logistic regression was performed, with the largest class being the reference group to determine clinical predictors of subgroup membership.

RESULTS

A total of 443 and 556 patients were included in the iHOT-12 and HOS-SS analyses, respectively. For the iHOT-12, we identified the following 3 subgroups: early progressors (70%), late regressors (22.3%), and late progressors (7.7%). Predictors of late regression were workers' compensation status, psychiatric history, preoperative chronic pain, and lower preoperative iHOT-12 scores; and late progressors were less likely to participate in sports. For the HOS-SS, we identified the following 4 subgroups: early progressors (47.7%), late regressors (17.4%), late progressors (6.8%), and steady progressors (28.1%). Predictors of less favorable recovery trajectories (late regressors and late progessors) were older age, male sex, back pain, psychiatric history, preoperative chronic pain, greater alpha angle, and lower preoperative HOS-SS scores.

CONCLUSION

Using the growth mixture modeling, 3 natural courses of health-related quality of life (early progression, late regression, and late progression) and 4 natural courses of recovery of athletic function (steady progression, late regression, late progression, and early progression) were identified. Preoperative psychiatric conditions, chronic pain, workers' compensation status, and lower iHOT-12 scores were predictive of less than favorable trajectories of recovery according to the iHOT-12, and male sex, older age, back pain, preoperative narcotic use, and lower preoperative HOS-SS were predictors of less favorable recovery trajectories according to the HOS-SS.

Gender and Age-Specific Differences Observed in Rates of Achieving Meaningful Clinical Outcomes 5-Years After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

PURPOSE

To compare the impact of age and gender on achieving meaningful outcomes among minimum patients 5 years after undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

METHODS

Consecutive patients undergoing hip arthroscopy for FAIS by a single fellowship-trained surgeon between January 2012 and October 2014 were analyzed. Study inclusion criteria included any patient undergoing primary hip arthroscopy for FAIS, with 5 years follow-up. Preoperative and 5-year postoperative functional scores were collected, including the Hip Outcome Score Activities of Daily Living Subscale (HOS-ADL), HOS-Sport Subscale (HOS-SS), modified Harris hip score (mHHS), and Visual Analog Scale for satisfaction. Patients were matched 1:1 by gender and age to compare outcomes between these 2 demographics. Minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) were calculated for each functional measure and compared by gender and age.

RESULTS

Of the 340 patients (70.5%) with 5 years' follow up, 150 were matched by gender and age into one of the following groups: female patients <30 years, female patients 30 to 45 years, female patients >45 years, male patients <30 years, male patients 30 to 45 years, and male patients >45 years of age. At minimum 5-year follow-up, all 6 groups demonstrated statistically significant improvement in the functional outcome score averages and pain (P < .001 for all). Both within gender and within age category analysis of postoperative functional scores did not demonstrate any statistical differences (P > .05). Analysis of achieving MCID and PASS demonstrated that females had higher rates of reaching the HOS-SS and mHHS threshold for achieving MCID as compared to their male counterparts (P < .05). Furthermore, patients <30 years old had higher rates of reaching the HOS-ADL and mHHS for achieving PASS when compared to patients >45 years old (P < .05).

CONCLUSION

The majority of patients achieve clinically significant outcome improvement at 5-year follow-up after arthroscopic FAIS surgery. Females reach the mHHS threshold for achieving MCID at significantly higher rates than males. Patients <30 years of age achieved PASS on the HOS-ADL and mHHS threshold scores at higher rates than those >45 years old.

LEVEL OF EVIDENCE

Level III, case-control study.

Use of Younger Patient Age and Greater Anterior Center-Edge Angle to Predict the Need for Bilateral Hip Arthroscopy in Patients With Bilateral Femoroacetabular Impingement-Related Hip Pain

BACKGROUND

In patients with symptomatic femoroacetabular impingement syndrome, bilateral hip pain has been reported to occur in high frequency. However, not all patients require bilateral hip arthroscopy.

PURPOSE

To determine the incidence, patient-specific variables, and postoperative outcomes in patients who presented with bilateral hip pain at the time of index hip arthroscopy and underwent subsequent contralateral arthroscopic hip surgery.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients who presented with bilateral hip pain, underwent primary hip arthroscopy between January 2012 and June 2018 for indication of femoroacetabular impingement syndrome, and had minimum 2-year follow-up were retrospectively analyzed. Baseline descriptive data, preoperative hip range of motion, and radiographic measurements were recorded with pre- and postoperative patient-reported outcomes (PROs). Independent samples t test was used to compare continuous variables, and chi-square test was used to compare categorical variables between patients undergoing unilateral and bilateral surgery. Bivariate correlations and a multivariable binary logistic regression were performed to determine factors predictive of the need for future contralateral hip arthroscopy.

RESULTS

In total, 108 patients were identified who reported bilateral hip pain during the index evaluation, underwent primary hip arthroscopy, and had 2-year follow-up. Among these, 42% (n = 45) elected to undergo hip arthroscopy on the contralateral hip at a mean of 6.0 months (range, 1-17 months) after the index surgery. Patients requiring bilateral surgery were significantly younger (P = .004) and had a larger preoperative anterior center-edge angle (ACEA; P = .038) when compared with patients who had unilateral surgery. There were no significant differences in alpha angle measurements between patients who had unilateral and bilateral surgery. On bivariate analysis, younger age at the time of the index surgery (r = -0.272; P = .005) and preoperative ACEA (r = 0.249; P = .016) were significantly correlated with the need for bilateral surgery. On multivariate analysis, younger age remained a significant predictor for bilateral surgery (odds ratio, 0.95; 95% CI, 0.91-0.99). Patients who underwent bilateral hip arthroscopy reported significant improvement in all PROs (P < .001), with a significantly greater mean Hip Outcome Score- Sports Specific Subscale score when compared with patients undergoing unilateral surgery (P = .037).

CONCLUSION

Subsequent contralateral hip arthroscopy was performed in 42% of patients who presented with bilateral hip pain. Younger age at the time of the index surgery and greater ACEA were predictive of the need for contralateral surgery. Patients undergoing bilateral surgery reported significantly improvement in PROs at minimum 2-year follow-up.

Complete Capsular Closure Provides Higher Rates of Clinically Significant Outcome Improvement and Higher Survivorship Versus Partial Closure After Hip Arthroscopy at Minimum 5-Year Follow-Up

PURPOSE

To (1) compare the rates of reaching threshold hip-specific outcome scores for achieving the minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) in patients who underwent partial versus complete T-capsulotomy repair and (2) identify the failure rates in each group 5 years after undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

METHODS

Data from consecutive patients who underwent hip arthroscopy for FAIS performed by a single fellowship-trained surgeon from January 2011 to March 2013 were collected and analyzed. Baseline data, hip-specific outcomes, and clinical failure rates were recorded at a minimum of 5 years postoperatively. Patients with partial T-capsulotomy repair were matched 1:3 by age, body mass index, and sex to patients with complete T-capsulotomy repair. Threshold scores for achieving the MCID and PASS were calculated and compared between the 2 groups. Additionally, rates of revision and conversion to total hip arthroplasty (THA) were compared between the groups.

RESULTS

A total of 379 patients were available for analysis (39 partial and 340 complete repairs), with 100 patients included in the matching process (25 in the partial-repair group and 75 in the complete-repair group). Comparison of radiographic parameters, including the Tönnis grade, alpha angle, and lateral center-edge angle, between the 2 groups showed no statistically significant difference (P > .05 for all). Comparison of postoperative score averages between the partial- and complete-closure groups showed a significant difference in the Hip Outcome Score-Activities of Daily Living Subscale (85.4 ± 17.7 vs 94.6 ± 7.8, P < .001), Hip Outcome Score-Sports Subscale (76.6 ± 26.2 vs 89.3 ± 16.8, P = .034), modified Harris Hip Score (83.2 ± 19.7 vs 90.5 ± 11.2, P = .035), and visual analog scale pain score (24.5 ± 30.8 vs 13.4 ± 15.8, P = .035). A total of 65 complete-repair patients (95.6%) achieved the MCID for at least 1 outcome measure versus 18 patients with partial repair (78.3%) (P = .04). A total of 69 complete-repair patients (92%) achieved the PASS for at least 1 outcome measure versus 18 partial-repair patients (72%) (P = .017). Of the 39 partial-repair patients, 35.9% (n = 14) underwent revision or conversion to THA, as compared with 2.9% (n = 10) in the overall cohort.

CONCLUSIONS

At a minimum 5-year follow-up, patients with complete capsular closure after hip arthroscopy for FAIS show superior long-term outcomes and achieve higher rates of meaningful clinical success when compared with patients with partial capsular closure. Furthermore, patients with partial capsular repair undergo revision or conversion to THA at high rates.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Hip Arthroscopy for Femoroacetabular Impingement Syndrome in Adolescents Provides Clinically Significant Outcome Benefit at Minimum 5-Year Follow-Up

PURPOSE

To report the rates of achieving clinically significant outcomes as defined by the minimal clinically important difference (MCID), patient acceptable symptomatic state (PASS), or substantial clinical benefit (SCB) in adolescent patients and the rates of clinical failure 5 years after undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

METHODS

Data from consecutive adolescent patients (defined by the American Academy of Pediatrics as age 11 to 21 years) who underwent primary hip arthroscopy with routine capsular closure for the treatment of FAIS between January 2012 and January 2015 by a single, fellowship-trained surgeon was collected. Baseline data, clinical outcomes including Hip Outcome Score (HOS)-Activities of Daily Living, HOS-Sports Subscale, modified Harris hip score, international Hip Outcome Tool, and clinical failure rates were recorded at 5 years after operative. Clinical failure was defined by revision hip arthroscopy or conversion to total hip arthroplasty. Clinically significant outcomes was defined as achieving MCID, PASS, or SCB on at least 1 hip-specific outcome measure.

RESULTS

Of the 139 eligible patients, a total of 85 (60.4%) patients (85 hips) were included in the final analysis, with an age and body mass index average of 17.6 ± 2.5 years (range 13-21) and 22.3 ± 3.1 kg/m², respectively. The majority of the patients were female (80.6%) and participated in sports (76.2%). There was statistically significant difference between preoperative and postoperative score averages across every reported outcome (P < .001). At 5 years, 88.4%, 67.6%, and 64.9% reached at least 1 threshold for achieving MCID, PASS, and SCB, respectively, whereas 89.2% achieved at least one of the meaningful outcome thresholds. Last, 2 patients (2.4%) failed clinically, with both undergoing revision (2.4%) because of continued pain. There were no conversions to total hip arthroplasty.

CONCLUSION

This study demonstrated that a large majority (89.2%) of adolescent patients undergoing primary arthroscopic treatment for symptomatic FAIS achieved meaningful clinically significant outcomes. Furthermore, only 2.4% of patients failed clinically, requiring revision hip arthroscopy because of continued pain.

LEVEL OF EVIDENCE

IV, Retrospective Case Series.

Patients With Borderline Hip Dysplasia Achieve Clinically Significant Improvement After Arthroscopic Femoroacetabular Impingement Surgery: A Case-Control Study With a Minimum 5-Year Follow-up

BACKGROUND

Hip arthroscopy for the treatment of femoroacetabular impingement syndrome (FAIS) in patients with borderline hip dysplasia (BHD) is becoming a more common practice. However, the literature on achieving meaningful outcomes at midterm follow-up, as well as predictors of these outcomes, is limited.

PURPOSE

To (1) compare the rates of achieving meaningful clinical outcomes between patients with and without BHD and (2) identify the predictors for achieving clinical success among patients with BHD 5 years after undergoing hip arthroscopic surgery for FAIS.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data from consecutive patients who underwent primary hip arthroscopic surgery with routine capsular closure for the treatment of FAIS between January 2012 and August 2014 were collected and retrospectively analyzed. Patients with BHD (lateral center-edge angle [LCEA] 20°-25°) were matched 1:2 by age (±1 year) and body mass index (BMI; ±5 kg/m²) to control patients with normal acetabular coverage (LCEA 25°-40°). Data collected included baseline and 5-year postoperative patient-reported outcomes. The minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) were calculated for each patient-reported outcome measure and compared between the 2 groups. A binary logistic regression analysis was used to identify significant predictors of achieving the MCID and PASS in the BHD group.

RESULTS

The MCID in the BHD group was defined as 9.6, 14.1, and 9.5 for the Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale, and modified Harris Hip Score, respectively. Threshold scores for achieving the PASS in both groups were 90.9, 76.6, and 81.9, respectively. A total of 88 patients were identified with having BHD and were matched to 176 controls. No statistical differences were identified for age, BMI, or sex. Both the BHD and the non-BHD groups had statistically significant increases in patient-reported outcome scores over the 5-year period, but the difference in both groups was not statistically significant (P > .05 for all). There was no statistical difference in the frequency of patients in the BHD and non-BHD groups achieving the MCID (86.6% vs 85.2%, respectively; P = .804) or PASS (76.0% vs 73.7%, respectively; P = .675) on at least 1 outcome measure. The logistic regression model demonstrated that being physically active (odds ratio [OR], 27.59; P = .005) and being female (OR, 14.64; P = .025) were independent predictors of achieving the MCID, while running (OR, 11.1; P = .002), being female (OR, 7.6; P = .011), and a larger preoperative LCEA (OR, 2.3; P = .001) were independent preoperative predictors of achieving the PASS.

CONCLUSION

The rates of achieving clinical success 5 years after undergoing arthroscopic treatment with capsular closure for FAIS were not significantly different between patients with BHD and those with normal acetabular coverage. Being physically active, running for exercise, female sex, and a larger LCEA were preoperative predictors of achieving clinical success at 5 years in patients with BHD.

Intraoperative radiation exposure in hip arthroscopy: a systematic review

Fluoroscopy is used in hip arthroscopy (HA) for portal placement, instrument localisation, and guidance in bony resection. The recent increase in arthroscopic hip procedures may place patients and surgeons at risk for increased radiation exposure and radiation-induced complications. The purpose of the current systematic review was to assess intraoperative radiation exposure in HA. The systematic review was conducted according to PRISMA guidelines; inclusion criteria were studies assessing radiation exposure in HA. 9 studies including 994 patients were included. Mean age was 38.6 years and 48% (436 of 906) were female. Mean time of fluoroscopy exposure was 0.58 minutes. Dose area product was 129.5 cGycm². Mean intraoperative absorbed radiation dose studies was 12.6 mGy. Mean intraoperative effective dose was 0.48 mSv. The mean occupational exposure to the surgeon per case was 0.0031 mSv. Higher patient body mass index (BMI) correlated to greater patient effective and cumulative dose (p < 0.05, r = 0.404), and greater occupational exposure (p < 0.001, r = 0.460). Increasing surgeon experience decreased fluoroscopy time (p = 0.039) and radiation dose (p = 0.002). Radiation dose and effective dose were well under the thresholds for deterministic effects (2 Gy) and annual radiation exposure for occupational workers (20 mSv). Intraoperative radiation exposure to patients and surgeons is within acceptable annual radiation limits. Ensuring careful selection of perioperative imaging modalities, proper protective shielding, specifically the use of leaded eyeglasses, and optimal C-arm positioning are key strategies to reduce radiation exposure to patients and surgeons alike.

Mirror Image Modeling of Acetabular Rim Thickness Differences in Patients With Unilateral Femoroacetabular Impingement Syndrome

Purpose

To use mirror imaging to identify the location and magnitude of difference in acetabular rim morphology between the symptomatic and unaffected acetabula in patients with symptomatic unilateral pincer-type or mixed femoroacetabular impingement syndrome (FAIS) using 1-dimensional models created with computed tomography (CT).

Methods

CT scans of bilateral hips in 33 patients diagnosed with unilateral pincer-type or mixed FAIS were obtained. Three-dimensional bilateral hip models were constructed, and the unaffected hemipelvis was superimposed onto the symptomatic side to compare acetabular thickness. Protrusion of the symptomatic side was recorded, and rim morphology was divided into clock face quadrants to analyze the location of greatest magnitude of difference between affected and unaffected acetabula. Analysis of the quadrants was performed using analysis of variance with post hoc Bonferroni correction.

Results

The study group consisted of more females (51.6%) than males, with an average age of 35.72 ± 7.8 years and an average body mass index of 24.3 ± 4.1 kg/m². Of the 33 hips included, 14 were isolated pincer-type FAIS and 19 were mixed. The average preoperative symptomatic side lateral center edge angle was 37.5° ± 7.2° compared with 29° ± 5.1° on the asymptomatic side (P = .001). The symptomatic acetabular rim was on average 0.43 ± 0.18 mm thicker than the corresponding location on the unaffected rim. When the acetabulum was divided into clock face quadrants, the 12 to 3 o'clock position showed the greatest difference between symptomatic and unaffected sides (0.55 ± 0.18 mm) compared with the 3 to 6 o'clock position (0.4 ± 0.28 mm; P = .006), 6 to 9 o'clock (0.34 ± 0.07 mm; P < .001), and 9 to 12 o'clock (0.38 ± 0.03; P = .001).

Conclusions

Patients with unilateral, symptomatic pincer-type or mixed FAIS show statistical differences in rim thickness between the affected and unaffected acetabula. Small changes in acetabular rim morphology on the order of ≤0.5 mm may be the difference between symptomatic FAIS and the unaffected hip.

Level of Evidence

IV, case series.

Defining Meaningful Functional Improvement on the Visual Analog Scale for Satisfaction at 2 Years After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

PURPOSE

To (1) define Substantial Clinical Benefit (SCB), Patient Acceptable Symptomatic State (PASS), and Minimal Clinically Important Difference (MCID) for the visual analog scale (VAS) Satisfaction in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS), and (2) identify preoperative predictors of achieving each outcome end-point.

METHODS

Data from consecutive patients who underwent primary hip arthroscopy between November 2014 and January 2017 were prospectively collected and retrospectively analyzed. Inclusion criteria consisted of patients with clinical and radiographic diagnosis of FAIS, who failed nonoperative treatment, underwent primary hip arthroscopy to address the FAIS, and had at minimum 2-year follow-up. Baseline data and postoperative patient-reported outcome scores were recorded at 2 years postoperatively. To quantify clinical significance of outcome achievement on the VAS)Satisfaction, we calculated MCID, PASS, and SCB for this outcome measure. A multivariate logistic regression analysis was used to identify preoperative predictors of achieving SCB, PASS, and MCID satisfaction.

RESULTS

A total of 335 patients were included in the final analysis, with an average age and body mass index (BMI) of 32.8 (standard deviation ± 12.4) years and 25.2 (standard deviation ± 5.3), respectively, and the majority being female (69.3%). The values on the VAS satisfaction were identified to represent MCID, PASS, and SCB, respectively: 52.8, 80.9, and 89.7. The rates of achieving clinically significant improvement on the VAS Satisfaction was 85.6%, 68.1%, and 56.9% for MCID, PASS, and SCB, respectively. A larger preoperative alpha angle was predictive for achieving SCB (odds ratio [OR], 1.076; P = .046), whereas lower BMI (OR, 0.955; P = .047) and larger preoperative alpha angle (OR, 1.12; P = .025) were predictors for achieving PASS.

CONCLUSIONS

This study identified threshold VAS satisfaction scores of 52.8, 80.9, and 89.7 for achieving MCID, SCB, and PASS, respectively, at 2-year follow-up following hip arthroscopy for FAIS. Furthermore, preoperative variables including larger preoperative alpha angles and lower BMI are predictors of achieving superior clinical satisfaction.

LEVEL OF EVIDENCE

Level IV, Case Series.

Defining the Clinically Meaningful Outcomes for Arthroscopic Treatment of Femoroacetabular Impingement Syndrome at Minimum 5-Year Follow-up

BACKGROUND

Minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) have gained prominence as important variables in the orthopaedic outcomes literature. In hip preservation surgery, much attention has been given to defining early clinically meaningful outcome; however, it is unknown what represents meaningful patient-reported outcome improvement in the medium to long term.

PURPOSE

(1) To define MCID, PASS, and SCB at a minimum 5 years after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) and (2) to evaluate the time-dependent nature of MCID, PASS, and SCB.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients undergoing primary hip arthroscopy for FAIS between January 2012 and March 2014 were included. Clinical and demographic data were collected in an institutional hip preservation registry. MCID, PASS, and SCB were calculated for each outcome score including the Hip Outcome Score-Activities of Daily Living subscale (HOS-ADL), Hip Outcome Score-Sport-Specific subscale (HOS-SS), modified Harris Hip Score (mHHS), and International Hip Outcome Tool (iHOT-12) at 1, 2, and 5 years. MCID was calculated by use of a distribution-based method, whereas PASS and SCB were calculated by use of an anchor method.

RESULTS

The study included 283 patients with a mean ± SD age of 34.2 ± 11.9 years. The mean changes in 1-year, 2-year, and 5-year scores, respectively, required to achieve MCID were as follows: HOS-ADL (8.8, 9.7, 10.2); HOS-SS (13.9, 14.3, 15.2); mHHS (6.9, 9.2, 11.4); and iHOT-12 (15.1, 13.9, 15.1). The threshold scores for achieving PASS were as follows: HOS-ADL (89.7, 88.2, 99.2); HOS-SS (72.2, 76.4, 80.9); mHHS (84.8, 83.3, 83.6); and iHOT-12 (69.1, 72.2, 74.3). Last, the threshold scores for achieving SCB scores were as follows: HOS-ADL (89.7, 91.9, 94.6); HOS-SS (78.1, 77.9, 85.8); mHHS (86.9, 85.8, 94.4); and iHOT-12 (72.6, 76.8, 87.5). More patients achieved MCID, SCB, and PASS at 2-year compared with 1-year follow-up; however, by 5 years, fewer patients had achieved clinically meaningful outcome (minimum 1-, 2-, and 5-year follow-up, respectively: MCID, 82.6%, 87.3%, 79.3%; PASS, 67.6%, 74.9%, 67.5%; SCB, 62.3%, 67.2%, 56.6%).

CONCLUSION

The greatest proportion of patients achieved MCID, PASS, and SCB at 2-year follow-up after arthroscopic treatment of FAIS compared with 1- and 5-year time points. Improvements were maintained out to 5-year follow-up, although the proportion of patients achieving clinical significance was slightly decreased.

Application of Machine Learning for Predicting Clinically Meaningful Outcome After Arthroscopic Femoroacetabular Impingement Surgery

BACKGROUND

Hip arthroscopy has become an important tool for surgical treatment of intra-articular hip pathology. Predictive models for clinically meaningful outcomes in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS) are unknown.

PURPOSE

To apply a machine learning model to determine preoperative variables predictive for achieving the minimal clinically important difference (MCID) at 2 years after hip arthroscopy for FAIS.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data were analyzed for patients who underwent hip arthroscopy for FAIS by a high-volume fellowship-trained surgeon between January 2012 and July 2016. The MCID cutoffs for the Hip Outcome Score-Activities of Daily Living (HOS-ADL), HOS-Sport Specific (HOS-SS), and modified Harris Hip Score (mHHS) were 9.8, 14.4, and 9.14, respectively. Predictive models for achieving the MCID with respect to each were built with the LASSO algorithm (least absolute shrinkage and selection operator) for feature selection, followed by logistic regression on the selected features. Study data were analyzed with PatientIQ, a cloud-based research and analytics platform for health care.

RESULTS

Of 1103 patients who met inclusion criteria, 898 (81.4%) had a minimum of 2-year reported outcomes and were entered into the modeling algorithm. A total of 74.0%, 73.5%, and 79.9% met the HOS-ADL, HOS-SS, and mHHS threshold scores for achieving the MCID. Predictors of not achieving the HOS-ADL MCID included anxiety/depression, symptom duration for >2 years before surgery, higher body mass index, high preoperative HOS-ADL score, and preoperative hip injection (all P < .05). Predictors of not achieving the HOS-SS MCID included anxiety/depression, preoperative symptom duration for >2 years, high preoperative HOS-SS score, and preoperative hip injection, while running at least at the recreational level was a predictor of achieving HOS-SS MCID (all P < .05). Predictors of not achieving the mHHS MCID included history of anxiety or depression, high preoperative mHHS score, and hip injections, while being female was predictive of achieving the MCID (all P < .05).

CONCLUSION

This study identified predictive variables for achieving clinically meaningful outcome after hip arthroscopy for FAIS. Patient factors including anxiety/depression, symptom duration >2 years, preoperative intra-articular injection, and high preoperative outcome scores are most consistently predictive of inability to achieve clinically meaningful outcome. These findings have important implications for shared decision-making algorithms and management of preoperative expectations after hip arthroscopy for FAI.

Comparing Outcomes of Competitive Athletes Versus Nonathletes Undergoing Hip Arthroscopy for Treatment of Femoroacetabular Impingement Syndrome

BACKGROUND

A growing number of studies have examined return to sport in competitive athletes after undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS); however, few have evaluated the rate of achieving meaningful clinical outcomes in this group.

PURPOSE

To determine if competitive athletes (professional, semiprofessional, or collegiate) have better 2-year patient-reported outcomes and achieve the minimal clinically important difference (MCID) and substantial clinical benefit at higher rates when compared with nonathletes undergoing hip arthroscopy for the treatment of FAIS.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The study was a retrospective analysis of all consecutive patients who identified as either a competitive athlete or a nonathlete and had undergone hip arthroscopy for FAIS by a single fellowship-trained surgeon between January 2012 and April 2017. Patients in the 2 groups were matched 1:2 by age, sex, and body mass index. Baseline and clinical outcomes, including the Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale (HOS-SS), modified Harris Hip Score, and international Hip Outcome Tool-12, were collected preoperatively and at 2 years postoperatively and compared between the groups. The MCID and substantial clinical benefit were calculated for each group separately and compared using chi-square analysis.

RESULTS

A total of 59 competitive athletes and 118 nonathletes were included in the final analysis. Most of the competitive athletes were soccer players (23.7%), followed by softball players (10.2%) and runners (10.2%). Postoperative score comparison between competitive athletes and nonathletes demonstrated a statistically significant difference in the HOS-SS (mean ± SD, 84.5 ± 19.0 vs 76.1 ± 23.8; P = .02). Meaningful outcome analysis demonstrated that competitive athletes had a higher rate of achieving the HOS-SS threshold for the MCID (97.4% vs 82.5%; P = .021). There was no other difference in frequency of achieving the threshold for any other meaningful clinical outcome between the groups.

CONCLUSION

Hip arthroscopy for the treatment of FAIS in competitive athletes and nonathletes produced clinically meaningful outcomes in both patient groups. However, competitive athletes achieved the MCID on the HOS-SS at higher rates than nonathletes and had significantly higher scores at 2 years postoperatively on the HOS-SS.

Two-Year Patient-Reported Outcomes for Patients Undergoing Revision Hip Arthroscopy with Capsular Incompetency

PURPOSE

To determine clinical outcomes of patients undergoing revision hip arthroscopy for failure to improve with magnetic resonance imaging (MRI) and intraoperative evidence of a capsular incompetency as compared with (1) patients undergoing revision hip arthroscopy without evidence of a capsular incompetency and (2) patients undergoing primary surgery for femoroacetabular impingement syndrome (FAIS) at a minimum follow up of 2 years.

METHODS

Data from consecutive patients undergoing revision hip arthroscopy with MRI/arthrogram-confirmed capsular incompetency between January 2012 and June 2016 were analyzed. All revision patients with capsular incompetency was matched 1:1 by age and body mass index to FAIS revision patients without capsular incompetency and primary FAIS patients. Outcomes included the Hip Outcome Score (HOS)-Activities of Daily Living (ADL), HOS-Sports Subscale (SS), Modified Harris Hip Score (mHHS), pain, and satisfaction. The minimal clinically important difference was calculated for HOS-ADL, HOS-SS, and mHHS.

RESULTS

In total, 49 patients (54.4%) of 90 undergoing revision hip arthroscopy had MRI evidence of a capsular incompetency. Most patients were female (79.6%), with a mean age of 30 ± 10.5 years and body mass index of 25.7 ± 5.5. The difference among pre- and postoperative HOS-ADL, HOS-SS, mHHS, and visual analog scale score for pain were all statistically significant (P < .05). Analysis of reported outcomes among matched groups demonstrated statistically significant differences, with the group undergoing primary surgery having the greatest 2-year outcomes. Only 66.7% of patients undergoing revision surgery with capsular incompetency achieved a minimal clinically important difference; however, there was no significant difference when compared with revision patients without capsular incompetency. When compared with patients undergoing primary surgery, the difference in frequency was statistically significant (66.7% vs 91.3%; P < .001).

CONCLUSIONS

More than one half of patients undergoing revision hip arthroscopy had MRI and intraoperative evidence of capsular incompetency. Revision arthroscopy for capsular incompetency results in significantly improved 2-year outcomes. However, patients undergoing revision for capsular incompetency and intact capsule revision patients reported significantly lower outcomes compared with primary patients.

LEVEL OF EVIDENCE

Level III, Retrospective Comparative Study.

Is There an Association Between Preoperative Expectations and Patient-Reported Outcome After Hip Arthroscopy for Femoroacetabular Impingement Syndrome?

PURPOSE

To determine the relationship between preoperative patient expectation and postoperative satisfaction and overall patient-reported outcome (PRO) of patients undergoing hip arthroscopy for femoroacetabular impingement syndrome.

METHODS

Patients who underwent hip arthroscopy for femoroacetabular impingement syndrome completed the validated Hip Preservation Surgery Expectations Survey (21 questions; 0-100 range), as well as multiple PROs before surgery. High expectation was defined as an expectation score greater than 1 standard deviation above the mean. Patients with osteoarthritis, dysplasia, and those having undergone previous hip surgery were excluded. At 1 year postoperatively, patient visual analog scale (VAS) satisfaction, VAS pain, and PROs were assessed. Univariable and multivariate analyses were performed.

RESULTS

One-hundred fifty-three subjects (mean age 34.4 ± 12.6 years, female: 114 [71.3%], body mass index: 25.9 ± 5.3 kg/m²) participated. The mean expectation score was 84.5 ± 12.3. Significant correlations between high expectation scores (>96.7) and achieving the minimal clinical important difference (MCID) for modified Harris Hip Score (mHHS; r = 0.339; P = .043) and patient acceptable symptomatic state (PASS) for Hip Outcome Score-Activities of Daily Living Subscale (HOS-ADL; r = 0.207; P = .032) were observed. There were no significant correlations between high expectation scores and preoperative or postoperative PROs or patient satisfaction scores. χ² analysis demonstrated patients with greater expectations had increased rates of reaching MCID mHHS (92.3% vs 74.7%; P = .08), PASS mHHS (85.7% vs 69.7%; P = .046), and PASS HOS-ADL (93.8% vs 67.4%; P = .031).

CONCLUSIONS

High preoperative expectation is associated with increased rates of MCID/PASS achievement on mHHS and increased rate of PASS achievement on HOS-ADL. Preoperative expectations did not have an impact on Hip Outcome Score-Sports Subscale; however, patients with high preoperative expectations also have a high baseline Hip Outcome Score-Sports Subscale. In addition, preoperative expectations are not associated with postoperative VAS satisfaction scores.

LEVEL OF EVIDENCE

III; non-randomized cohort, therapeutic.

How Can We Define Clinically Important Improvement in Pain Scores After Hip Arthroscopy for Femoroacetabular Impingement Syndrome? Minimum 2-Year Follow-up Study

BACKGROUND

Patient postoperative pain is being increasingly reported in the field of hip preservation surgery. The visual analog scale (VAS) for pain is one of the most commonly utilized measures for perioperative pain assessment. Currently, there is limited understanding of clinically significant improvement in VAS pain.

PURPOSE

(1) To define the substantial clinical benefit (SCB), patient acceptable symptomatic state (PASS), and minimal clinically important difference (MCID) for the VAS pain score in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome after 2 years from surgery and (2) to identify preoperative predictors of achieving each outcome endpoint.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Data from consecutive patients who underwent primary hip arthroscopy between November 2014 and March 2017 were collected and analyzed. Baseline data and postoperative patient-reported outcome scores were recorded at 2 years postoperatively. To quantify clinical significance of outcome achievement for the VAS pain score, the MCID, PASS, and SCB were calculated.

RESULTS

A total of 976 patients were included in the final analysis. The VAS pain score threshold for achieving the MCID was defined as a decrease of 14.8; the PASS was defined as achieving a 2-year postoperative score of 21.6 points; and the SCB was defined as a decrease of 25.5 or a score of 15.4 points at 2 years. The rates of achieving the MCID, PASS, and SCB were 97.6%, 66.4%, and 71.2%, respectively. Regression analysis demonstrated that sports involvement, low body mass index, smaller preoperative alpha angle, and absence of articular damage and chondromalacia were predictive of achieving the PASS (all P < .05). Preoperative predictors for achieving the SCB included being male, no smoking history, smaller alpha angle, higher modified Harris Hip Score, and lower VAS pain score (all P < .05).

CONCLUSION

This study identified scores for VAS pain that can be used to define clinically significant outcome after arthroscopic treatment of femoroacetabular impingement syndrome. Specifically, a decrease in pain score of 14.8 was a clinically important improvement in VAS pain, while an absolute score <15.4 or a change of 25.5 represented the upper threshold of VAS pain improvement. Additionally, there were both modifiable and nonmodifiable factors that predicted achieving clinically significant levels of postoperative pain improvement.

Patients With Borderline Hip Dysplasia Achieve Clinically Significant Outcome After Arthroscopic Femoroacetabular Impingement Surgery: A Case-Control Study With Minimum 2-Year Follow-up

BACKGROUND

There is a growing trend for hip arthroscopists to treat patients with borderline hip dysplasia (BHD) for femoroacetabular impingement syndrome (FAIS) without addressing the acetabular coverage. However, the literature of outcomes and failure rates for these patients is conflicting.

PURPOSE

(1) To identify whether patients with BHD achieved 2-year similar patient-reported outcome, minimal clinically important difference (MCID), and patient acceptable symptomatic state (PASS) when compared with patients without BHD and (2) to identify predictors for achieving the MCID and PASS among patients with BHD who are undergoing hip arthroscopy for FAIS.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data from consecutive patients who underwent primary hip arthroscopy with routine capsular closure for the treatment of FAIS between January 2012 and January 2017 were collected and retrospectively analyzed. Patients with BHD (lateral center-edge angle [LCEA], 20°-25°) were matched 2:1 by age, sex, and body mass index (BMI) to control patients with normal acetabular coverage (LCEA, >25°-40°). Patient-reported outcome, MCID, and PASS were compared between the groups. Multivariate logistic regression analysis identified significant predictors of achieving the MCID and PASS in the BHD group.

RESULTS

The MCID in the BHD group was defined as 9.2, 13.7, 8.5, and 15.2 for the Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sport Specific, modified Harris Hip Score, and iHOT-12, respectively. Threshold scores for achieving the PASS in both groups were 87.9, 76.4, 78.1, and 60.0. A total of 112 patients were identified as having BHD (LCEA, 20°-25°) and were matched to 224 controls. Both groups saw statistically significant increases in score averages over the 2-year period; however, the differences between them were not statistically significant (P > .05 for all). There was no statistical difference in the frequency of the BHD and non-BHD cohorts achieving the MCID on at least 1 threshold score (86.6% vs 85.6%, P = .837) and the PASS (78.6% vs 79.8%, P = .79). There was, however, a statistically significant difference between the rates of patients with and without BHD achieving the PASS on the modified Harris Hip Score threshold (62.5% vs 74.5%, P = .028). The final logistic models demonstrated that lower BMI (odds ratio [OR], 0.872; P = .029), lower preoperative alpha angle (OR, 0.965; P = .014), and female sex (OR, 3.647; P = .03) are independent preoperative predictors of achieving the MCID, while lower preoperative alpha angle (OR, 0.943; P = .018) and self-reported limp (OR, 18.53; P = .007) are independent preoperative predictors of achieving the PASS.

CONCLUSION

Outcome improvements in patients with BHD who are undergoing arthroscopic treatment with capsular closure for FAIS are not significantly different from patients with normal acetabular coverage. Lower BMI, lower alpha angle, absence of limp, and female sex are preoperative predictors of achieving meaningful clinically significant outcome improvements in patients with BHD.

Survivorship and Outcome of Hip Arthroscopy for Femoroacetabular Impingement Syndrome Performed With Modern Surgical Techniques

BACKGROUND

Hip arthroscopy for femoroacetabular impingement syndrome (FAIS) is a rapidly growing field in sports surgery; however, factors associated with poor outcomes and identification of predictor models of inferior clinical outcomes is unclear.

PURPOSE

To analyze predictors of clinical failure and inferior clinical outcomes among patients undergoing hip arthroscopy for treatment of FAIS.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data were collected and analyzed from consecutive patients who underwent primary hip arthroscopy with routine capsular closure for the treatment of FAIS from a single fellowship-trained surgeon between January 2012 and November 2015. Baseline data, postoperative patient-reported outcomes, and rates of clinical failure and inferior clinical outcomes were recorded at 2 years postoperatively. Clinical failure was defined by revision hip arthroscopy or conversion to total hip arthroplasty. Inferior clinical outcome was defined as not reaching the minimal clinically important difference (MCID) or patient acceptable symptomatic state for Hip Outcome Score-Activities of Daily Living. A multivariate logistic regression analysis was used to identify significant predictors of clinical failure and inferior clinical outcome.

RESULTS

Out of 1161 eligible patients, 935 (80.5%) completed 2-year postoperative patient-reported outcomes. The mean ± SD age and body mass index were 33.3 ± 12.3 years and 25.4 ± 8.2 kg/m², respectively. The overall clinical failure rate was 3.6% (n = 34), including 23 cases (2.5%) of revision hip arthroscopy and 11 cases (1.2%) of conversion to total hip arthroplasty. Predictors of clinical failure were lower preoperative International Hip Outcome Tool score ( P = .016), chronic preoperative pain ( P = .001), and chondromalacia in the affected hip ( P = .04). The inferior clinical outcome group, consisting of those who failed to reach the MCID for Hip Outcome Score-Activities of Daily Living, included 256 patients (27.4%). Predictors of inferior clinical outcomes were Tönnis grade >1 ( P = .01), workers' compensation ( P < .001), and increased body mass index ( P = .02).

CONCLUSION

This study demonstrates that 73% of all patients treated for symptomatic FAIS with primary hip arthroscopy and routine capsular closure achieved the MCID. Clinical failure is predicted by a number of modifiable and nonmodifiable factors, including chronic preoperative pain and presence of chondromalacia. The current study updates the midterm failure rates and outcomes achievable with hip arthroscopy for FAIS.

Co-diagnoses of spondylolysis and femoroacetabular impingement: a case series of adolescent athletes

Locating the source of lumbopelvic–hip pain requires the consideration of multiple clinical pathways. Although low back pain has an incidence of 50% in the adolescent population, the pathophysiology in this population typically differs from that of other age groups. Dynamic mechanical impairments of the hip, such as femoroacetabular impingement, may contribute to the pathogenesis of adolescent low back pain. Eight adolescent male athletes who presented to a single provider with a primary complaint of low back pain with hip pain or motion loss on exam and were ultimately diagnosed with lumbar spondylolysis and dynamic mechanical hip issues between 2009 and 2011 were included. The age at spondylolysis diagnosis ranged from 15 to 19 years (mean ± standard deviation: 16.3 ± 1.3 years). Seven patients had cam-type impingement, whereas one presented with pincer-type impingement. All patients demonstrated either decreased internal rotation at 90 degrees of hip flexion and neutral abduction or pain on the Flexion Adduction Internal Rotation test on at least one of hip. All eight patients were treated initially with 6 weeks of physical therapy consisting of attempted restoration of hip motion and the graduated progression of hip and spine stabilization exercises. Five patients (62.5%) returned to sport at an average of 11.2 weeks (range: 6–16 weeks). For three patients (37.5%), hip pain and motion loss persisted, thus requiring surgery. All subjects had symptoms for at least 6 weeks, with 6 months as the longest duration. This report is the first documented series of adolescent athletes with co-diagnoses of spondylolysis and femoroacetabular impingement.

Study Information: This retrospective case series was approved by the Institutional Review Board at Hospital for Special Surgery.

RADIOGRAPHIC HIP OSTEOARTHRITIS IS PREVALENT, AND IS RELATED TO CAM DEFORMITY 12-24 MONTHS POST-HIP ARTHROSCOPY

BACKGROUND

The prevalence of radiographic hip osteoarthritis (OA), and its relationship with outcomes after hip arthroscopy is unclear.

OBJECTIVES

The aims of this study were to: (i) describe the prevalence of OA and cam deformity 12-24 months post hip arthroscopy; (ii) to determine the association between radiographic OA and cam deformity, surgical and clinical findings and symptoms; and (iii) describe the differences between legs for radiological and clinical findings.

STUDY DESIGN

Cross sectional study.

METHODS

Seventy patients, mean age 36.7(range 18-59) years, 12-24 months post-arthroscopy.

MAIN OUTCOME MEASURES

Outcomes were collected prospectively via clinical and radiographic examination. (i)Prevalence of OA and cam deformity measured on and anteroposterior pelvic radiographs; (ii)Hip disability and Osteoarthritis Outcome Score (HOOS) and International Hip Outcome Tool (iHOT-33) patient-reported outcomes (PROs); (iii)hip internal and external rotation range of motion (ROM). Associations between OA and surgical findings, PROs and clinical findings were determined using generalized estimated equations, between operated and non-operated sides.

RESULTS

The prevalence of OA was 37%. The likelihood of OA 12-24 months after surgery was positively associated with alpha angle size 12-24 months post-hip arthroscopy surgery (p=0.010). There were no differences between operated and non-operated legs in radiographic or clinical findings.

CONCLUSION

Radiographic OA is prevalent in a population which has undergone hip arthroscopy. Increased OA severity is associated with a higher alpha angle 12-24 months post-surgery.

LEVEL OF EVIDENCE

Cross-sectional study Level IV.

Femoral Version Abnormalities Significantly Outweigh Effect of Cam Impingement on Hip Internal Rotation

BACKGROUND

The purpose of this study was to investigate the effects of femoral version, cam-type femoroacetabular impingement (FAI), and the combination of the 2 on the passive hip range of motion (ROM).

METHODS

We prospectively analyzed a consecutive cohort of 220 patients (440 hips) who presented with unilateral or bilateral hip pain. The passive hip ROM was measured bilaterally with the patient in prone, supine, and lateral positions. Femoral version was measured and the presence of cam-type deformity was determined on preoperative computed tomography (CT) scans. Diagnostic findings of cam-type FAI included an alpha angle of >50° on CT radial sequences of the head-neck junction and a femoral head-neck offset ratio of <0.18 on both radiographs and CT.

RESULTS

Multivariate linear regression analysis confirmed that femoral version, as compared with the presence of a cam lesion, was a stronger independent predictor of internal rotation ROM. Conversely, the presence of a cam lesion resulted in a significant decrease in the passive hip flexion ROM (p < 0.001) with no additional effects due to the degree of femoral version. The passive hip internal rotation ROM in neutral flexion/extension and with the hip in 90° of flexion were maximized in patients with femoral anteversion and decreased significantly with each incremental decrease in femoral version (p < 0.001).

CONCLUSIONS

Abnormalities in femoral version significantly outweigh the effect of cam-type impingement on the passive hip internal rotation ROM. In contrast, the presence of a cam lesion significantly decreases the hip flexion ROM, irrespective of the degree of femoral version. These findings help to inform surgical decision-making for patients with cam-type FAI or femoral version abnormalities.

CLINICAL RELEVANCE

It is common clinical practice to ascribe loss of hip internal rotation to the presence of a cam lesion and to assume that arthroscopic femoral osteoplasty will substantially improve internal rotation postoperatively. Our study shows that the cam lesion is more intimately tied to hip flexion than to hip internal rotation. This result directly impacts the clinical assessment of a patient presenting with radiographic findings of FAI.

Editorial Commentary: Invisible, Odorless, and Deadly: Do Computed Tomography Scans in Young Patients With Hip Pain Cause Cancer?

Does imaging of the pelvis using a set of radiographs and computed tomography (CT) cause cancer? A computer-based simulation study using 5 different imaging and radiation dose protocols has calculated the lifetime risk of malignancy for young adults for pelvic radiographs and CT scans. The cumulative lifetime-attributable risk of cancer was 0.2% for males and 0.35% for females. This appears low but the numbers needed to harm were 952 for males and 564 for females. However, the authors have based their calculations on the linear no-threshold model, which is controversial, and a linear relationship between dose and risk may not exist.

Comparison of Radiographs and Computed Tomography for the Screening of Anterior Inferior Iliac Spine Impingement

PURPOSE

To compare radiographic and 3-dimensional (3D) computed tomography (CT) imaging modalities for the screening of anterior inferior iliac spine (AIIS) impingement by establishing imaging measurement related to the AIIS.

METHODS

Anteroposterior and false-profile radiographs and 3D CT scans were obtained on 10 human cadaveric pelvises. On the anteroposterior view for each methodology, 2 measurements were calculated: distance to the most lateral AIIS from the 12 o'clock position on the acetabular rim, and the angle between the lateral AIIS and the sagittal plane. On the false-profile view for each methodology, 2 measurements were calculated: distance to the anterior AIIS from the 12 o'clock position on the acetabular rim, and the angle between the anterior AIIS and the sagittal plane. Inter-rater and intrarater reliability analyses were performed for both methods in addition to an intermethod analysis.

RESULTS

The radiographic false-profile view was the most repeatable orientation, with intraclass correlation coefficients showing excellent reproducibility in both inter-rater (angle: 0.980, distance: 0.883) and intrarater (angle: 0.995, distance: 0.995) analyses. The mean distance from the 12 o'clock position of the acetabular rim to the most anterior/lateral aspect of the AIIS was 41.4 mm and 16.0 mm on the radiographic false-profile and anteroposterior views, respectively. Intermethod analysis showed a systematic, quantitative bias between modalities (anteroposterior view: -4.1 mm, 6.7°; false-profile view: -0.1 mm, 8.3°), which will remain relatively consistent as evidenced by the strong individual reproducibility of each measurement.

CONCLUSIONS

AIIS morphology in relation to the acetabular rim 12 o'clock position and its angle relative to the sagittal plane can be quantitatively determined using either radiographic or 3D CT imaging modalities.

CLINICAL RELEVANCE

Radiographic evaluation may be a valuable tool in the screening of AIIS impingement.

Orthopaedic surgeons' use and knowledge of ionizing radiation during surgical treatment for femoroacetabular impingement

PURPOSE

To better understand how radiograph imaging is currently used throughout perioperative care for femoroacetabular impingement (FAI) and to define surgeon knowledge and perspective on radiation safety when treating FAI.

METHODS

An online questionnaire was designed to be completed by hip arthroscopists on the imaging modalities and projections they use during evaluation and treatment of FAI and the associated radiation exposures and safety. A sample of practicing attending orthopaedic surgeons was surveyed via an anonymous survey link emailed to corresponding authors on publications related to FAI. The anonymous survey link was also provided to orthopaedic surgeons at the 2014 Vail Hip Symposium.

RESULTS

Ninety-one surgeons completed the survey. Of these participants, 72 surgeons (79.1 %) indicated they use pre-operative radiographs and intra-operative spot fluoroscopic images during FAI treatment. Thirty-three surgeons (36.3 %) use pre-operative computed tomography (CT). Twenty-three surgeons (25.3 %) use real-time moving fluoroscopy. A majority of surgeons incorrectly answered multiple-choice questions about which C-arm positions and settings result in the lowest doses of radiation to the surgeon or patient. Eighty-three surgeons (91.2 %) indicated they believe most orthopaedic surgeons need to be more informed about radiation safety.

CONCLUSIONS

This study gives a quantitative representation of the imaging modalities and projections utilized during perioperative treatment for FAI. This study also identified a lack of knowledge of radiation safety among orthopaedic surgeons treating patients with FAI and demonstrates the need for greater education.

LEVEL OF EVIDENCE

IV.

Prevalence of Cam-Type Morphology in Elite Ice Hockey Players

BACKGROUND

Femoroacetabular impingement (FAI) has been increasingly recognized as a cause of hip pain in athletes at all levels of competition, specifically ice hockey players.

PURPOSE/HYPOTHESIS

The purpose of this study was to define the prevalence of cam and pincer radiographic deformity in elite ice hockey players. The hypothesis was that elite hockey players will have a higher prevalence of radiographic hip abnormalities compared with the general population.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Anteroposterior and frog-leg lateral radiographs on 137 elite ice hockey players were prospectively obtained during the 2014-2015 preseason entrance examinations. Study participants included National Hockey League roster players as well as the respective farm team members. Demographic data were collected, including age, position, shooting side, and any history of hip pain or hip surgery. Patients with a history of hip surgery were excluded from the analysis. A single sports medicine fellowship-trained orthopaedic surgeon used standard radiographic measurements to assess for the radiographic presence of cam or pincer deformity. Radiographs with an alpha angle ≥55° on a frog-leg lateral view were defined as cam-positive. Each participant underwent a preseason physical examination with an assessment of hip range of motion and impingement testing.

RESULTS

A total of 130 elite ice hockey players were included in the analysis; 180 (69.4%) hips met radiographic criteria for cam-type deformity. The prevalence in right and left hips was 89 (69.5%) and 91 (70.0%), respectively; 70 (60.8%) players demonstrated bilateral involvement. Hips with cam deformity had a mean alpha angle of 67.7° ± 8.3° on the right and 68.9° ± 9.0° on the left. Of the patients with alpha angles ≥55°, 5.6% (5/89) had a positive anterior impingement test of the right hip, while 11% (10/91) had positive anterior impingement test of the left. Players with radiologic cam deformity had a statistically significant deficit in external rotation of the right hip, as well as in both internal and external rotation of the left hip, compared with those with normal alpha angles. When assessing for crossover sign, 64 of 107 (59.8%) had a positive radiographic finding. Forty-one players (38.3%) had evidence of a crossover sign of the right hip and 42 (39.3%) of the left. When comparing position players, goalies had the highest prevalence of cam-type deformity (93.8%) and the least acetabular coverage.

CONCLUSION

The study data suggest that elite ice hockey players have a significantly higher prevalence of radiographic cam deformity in comparison to what has been reported for the general population.

Passive Hip Range of Motion Predicts Femoral Torsion and Acetabular Version

BACKGROUND

Orientation abnormalities of the acetabulum and femur have been implicated in early-onset coxarthrosis. The purpose of this study was to identify clinical examination findings predictive of such hip morphologies.

METHODS

A consecutive cohort of 221 patients (442 hips) undergoing hip arthroscopy was included. Demographic characteristics including age, diagnosis, sex, height, weight, body mass index (BMI), and physical activity level were recorded. Passive range of motion was measured for all hips. Preoperative computed tomography scans were utilized to measure femoral torsion and central acetabular version, and a combined femoral torsion-acetabular version (COTAV) index was defined as their sum.

RESULTS

The study cohort comprised 221 patients (sixty-four males, 157 females) with a mean age of 32.5 years and mean BMI of 24.2 kg/m(2). Overall, hips with femoral antetorsion and acetabular anteversion exhibited the greatest internal rotation range of motion at a neutral hip position (mean, 44.2°), whereas hips with femoral retrotorsion and acetabular retroversion demonstrated the lowest corresponding value (20.1°; p < 0.001). Femoral torsion was significantly associated with female sex (p < 0.001), BMI (p < 0.001), and presence of pathology corresponding to cam-type femoroacetabular impingement (FAI) (p = 0.044). Central acetabular version was significantly associated with age (p = 0.021), female sex (p < 0.001), and absence of mixed-type FAI pathology (p = 0.025). Increasing age and internal rotation range of motion at a neutral hip position were the most significant predictors of an increased COTAV index.

CONCLUSIONS

This study confirmed that passive hip range of motion significantly predicts combined femoral torsion and central acetabular version. Accurate clinical assessment of the COTAV index may inform surgical decision-making in hip preservation surgery.

Cumulative Radiation Exposure to Patients Undergoing Arthroscopic Hip Preservation Surgery and Occupational Radiation Exposure to the Surgical Team

PURPOSE

To quantify cumulative radiation exposure in patients undergoing arthroscopic hip preservation surgery and occupational exposure to operating room (OR) personnel during such surgery; a secondary objective of this study was to identify factors affecting radiation exposure in patients undergoing hip arthroscopy.

METHODS

Radiation exposure from all preoperative and intraoperative imaging studies was determined for 52 patients undergoing hip arthroscopy. Cumulative and effective radiation doses were calculated and correlated with pathology and body mass index (BMI). Badge dosimeters were worn by OR personnel to measure cumulative occupational exposure. A highly sensitive portable ion chamber was used to evaluate the radiation scatter during surgery performed on a high-BMI patient and a low-BMI patient to reflect a "worst-case scenario" and "best-case scenario," respectively.

RESULTS

Forty-three patients underwent procedures for femoroacetabular impingement (FAI) and 9 underwent procedures for soft-tissue pathologies (ST). The median cumulative exposure was 8.6 mGy and 5.0 mGy for FAI patients and ST patients, respectively (P = .01). The cumulative effective radiation dose was 490 mrem and 350 mrem for FAI patients and ST patients, respectively (P = .47). BMI significantly correlated with cumulative exposure (P = .0004) and trended toward significance with cumulative effective dose (P = .073). OR staff cumulative occupational exposure was low (9 mrem for the surgeon). Ion chamber data showed that increasing patient BMI resulted in increased occupational exposure.

CONCLUSIONS

The median cumulative effective radiation dose to patients undergoing arthroscopic hip preservation surgery is 490 mrem and results in an excess lifetime risk of death from cancer of 0.025%. Greater BMI correlates with increased cumulative radiation exposure and may increase risk to OR personnel. Occupational exposure to the surgical team from hip arthroscopy ranges from 7 to 9 mrem per 50 hip arthroscopies (+0.0005% excess lifetime risk of death from cancer).

LEVEL OF EVIDENCE

Level IV, diagnostic.