Clinical outcomes after revision hip arthroscopy in patients with femoroacetabular impingement syndrome (FAIS) are inferior compared to primary procedures. Results from the Danish Hip Arthroscopy Registry (DHAR)

Secondary Hip Labral Reconstruction Yields Inferior Minimum 2-Year Functional Outcomes to Primary Reconstruction Despite Comparable Intraoperative Labral Characteristics

PURPOSE

To compare intraoperative labral characteristics and minimum 2-year functional outcomes of allograft labral reconstruction in primary versus revision hip arthroscopy across multiple orthopaedic centers.

METHODS

A retrospective multicenter hip arthroscopy registry was queried for patients with completed labral reconstruction surgeries from January 2014 to March 2023 with completed 2-year international Hip Outcome Tool-12 (iHOT-12) reports. Age, sex, and major intraoperative variables also were collected. Patients were placed in cohorts based on whether their arthroscopic allograft labral reconstruction was a primary procedure or secondary procedure (reconstruction following failed hip arthroscopy). One-way analysis of variance was performed on continuous variables. χ2 test was performed on categorical variables. Achievement of minimal clinically important difference (MCID), Patient Acceptable Symptom State (PASS), and Substantial Clinical Benefit (SCB) also was assessed.

RESULTS

In total, 77 patients met the inclusion and exclusion criteria and had complete information. The primary reconstruction group (n = 50) was significantly older than the secondary reconstruction group (n = 27) (47.5 ± 10.5 vs 39.1 ± 8.8 years; P = .001). In both cohorts, most patients had labral bruising, advanced labral degeneration, and/or grade III complexity of labral tearing. There was no difference in any recorded intraoperative findings (P = .160, P = .783, P = .357, respectively). Each cohort experienced significant improvement in iHOT-12 scores (P < .0001). However, patients undergoing secondary labral reconstruction reported inferior iHOT-12 scores (60.1 ± 29.2 vs 74.8 ± 27.0; P = .030). Patients undergoing primary reconstruction were more likely to reach MCID, PASS, and nearly normal SCB (92 vs 66.7%, P = .024; 68.0 vs 40.7%, P = .021; 76.0 vs 48.1%, P = .014, respectively).

CONCLUSIONS

Primary and secondary allograft labral reconstruction show clinical improvement, but primary reconstruction demonstrates better outcomes and greater percentage of patients reaching MCID, PASS, and nearly normal SCB than reconstruction in the revision setting.

LEVEL OF EVIDENCE

Level III, retrospective comparative prognostic case-control study.

Editorial Commentary: Artificial Intelligence Analysis of Biomedical, Large, Clinical Registry Data Using Machine Learning Requires Tens of Thousands of Subjects and a Focus on Substantial Clinical Benefit: Minimal Clinically Important Difference Is too Low a Bar

As the field of arthroscopic hip preservation surgery grows, large high-quality registries represent a foundational study design for establishing whether hip arthroscopy is effective for patients with femoroacetabular impingement syndrome (FAIS). Original research publications from experienced high-volume surgeons tell us "Can it work". A registry tells us "Does it work?". The ability of preservation to truly preserve the joint, delay the arthritis process, and reduce the risk of arthroplasty requires long-term follow-up. A geographic registry can follow this. The registry represents the "real world", a heterogeneous set of variables pertaining to the doctor, patient, intervention, and outcome. The vast array of factors that can be analyzed before, during, and after surgery makes machine learning an ideal technique for analysis of large quantities of data. A global hip preservation surgery registry is a desirable and achievable goal. In order to optimally predict outcome of hip arthroscopy, given the known large number of patient- and hip-specific factors that influence outcomes, a deep learning model with tens of thousands of subjects for this medium-scale task would be needed. Measures of clinical relevance need to include more than just MCID (minimal clinically important difference), which is the lowest bar minimal threshold. Patient expectations often far exceed MCID-requiring other metrics like SCB (substantial clinical benefit), PASS (patient acceptable symptom state), and MOI (maximal outcome improvement). Registries should include validated, reliable, and responsive patient-reported outcome scores (e.g., International Hip Outcome Tool [iHOT-12]) with measures of clinical relevance and expectations assessed routinely. The United Kingdom's NAHR (Non-Arthroplasty Hip Registry) and Denmark's DHAR (Danish Hip Arthroscopy Registry) are the two largest geography-based registries in current hip preservation research both with 11 years of patient enrollment.

Patients Undergoing Revision Hip Arthroscopy Demonstrate Comparable Survivability and Improvement but Worse Postoperative Outcomes Compared to Patients Undergoing Primary Hip Arthroscopy: A Propensity Matched Study at Five-Year Follow-Up

PURPOSE

To compare mid-term clinical outcomes between patients undergoing primary hip arthroscopy (HA) versus revision hip arthroscopy (RHA) for femoroacetabular impingement syndrome (FAIS).

METHODS

A retrospective cohort study was conducted on 1,862 patients who underwent hip arthroscopy for FAIS from January 2012 to April 2017. Patients who underwent RHA were propensity matched in a 1:4 ratio by age, sex, body mass index (BMI), and exercise status to patients who underwent primary HA. Preoperative and postoperative radiographs were assessed. Patient-reported outcomes before and at 5 years after surgery, including the Hip Outcome Score Activities of Daily Living subscale (HOS-ADL) and Sports subscale (HOS-SS), modified Harris Hip Score (mHHS), international Hip Outcome Tool (iHOT-12), and Visual Analog Scale (VAS) for Pain and Satisfaction, were compared between groups. Minimally clinically important difference and patient-acceptable symptomatic state (PASS) achievement rates were compared using previously published thresholds.

RESULTS

Fifty-one patients who underwent RHA (35 female, 16 male; age 36.2 ± 10.2 years; BMI 26.5 ± 5.9) were followed up for 63.9 ± 9.2 months and then propensity matched in a 1:4 ratio by sex, age, and BMI to 204 control patients who underwent primary HA. At midterm follow-up, patients in the RHA cohort had significantly lower scores for HOS-SS (RHA 64.9 ± 32.5 vs HA 75.3 ± 26.2, P = .044), mHHS (RHA 72.2 ± 22.4 vs HA 80.1 ± 18.1, P = .039), and iHOT-12 (RHA 61.4 ± 29.3 vs HA 71 ± 27.6, P = .043) compared to primary HA patients. Rates of achieving PASS were significantly decreased for HOS-SS (RHA 38.3% vs HA 55.4%, P = .039) and iHOT-12 (RHA 41.9% vs HA 59.9%, P = .035) in the RHA cohort. There were no significant differences in rates of conversion to THA or subsequent reoperation on the index hip between groups.

CONCLUSIONS

Patients undergoing revision hip arthroscopy demonstrate comparable survivability and magnitude of improvement but may experience worse overall outcome scores and meet thresholds for clinically significant outcomes less often when compared to primary hip arthroscopy patients.

LEVEL OF EVIDENCE

Level III; retrospective comparative study.

Long-term Follow-up After Endoscopic Gluteal Repair Plus Hip Arthroscopy Shows Durable Results Using Validated Patient-Reported Outcome Scores That Largely Exceed the Minimal Clinically Important Difference and Patient Acceptable Symptom State

Gluteus medius and minimus tendon pathology is a common cause of lateral hip pain. In patients that are dissatisfied with their hip condition following non-surgical treatment, gluteal repair has demonstrated excellent short-, mid-, and now recently, long-term subjective patient-reported and objective clinician-measured outcomes. In patients with peritrochanteric hip pain, the proportion of their overall hip pain may be influenced by the hip joint due to conditions like Femoroacetabular Impingement Syndrome (FAIS), acetabular dysplasia, labral tears, and arthritis. Thus, surgical decision-making must include consideration of also addressing the joint at the same time as the gluteal repair. This is sometimes challenging due to the high frequency of observing labral injuries and cam/pincer/dysplasia morphology in patients without symptoms due to the "radiographic abnormalities". Labral pathology is also more prevalent in older patients, which happen to also be those individuals also presenting with symptomatic gluteal tendon pain. Both open and endoscopic approaches to the gluteal tendons have advantages and disadvantages without significant outcomes differences in short- or mid-term. Long-term clinical follow-up of patients treated with endoscopic gluteal repair with or without concomitant hip arthroscopy should be included in large national and international prospective registries using validated, reliable, and responsive patient-reported outcome scores, with clinical importance assessed using the minimal clinically important difference (MCID), patient acceptable symptom state (PASS), substantial clinical benefit (SCB), and maximal outcome improvement (MOI).

Stratified care in hip arthroscopy: can we predict successful and unsuccessful outcomes? Development and external temporal validation of multivariable prediction models

OBJECTIVE

Although hip arthroscopy is a widely adopted treatment option for hip-related pain, it is unknown whether preoperative clinical information can be used to assist surgical decision-making to avoid offering surgery to patients with limited potential for a successful outcome. We aimed to develop and validate clinical prediction models to identify patients more likely to have an unsuccessful or successful outcome 1 year post hip arthroscopy based on the patient acceptable symptom state.

METHODS

Patient records were extracted from the Danish Hip Arthroscopy Registry (DHAR). A priori, 26 common clinical variables from DHAR were selected as prognostic factors, including demographics, radiographic parameters of hip morphology and self-reported measures. We used 1082 hip arthroscopy patients (surgery performed 25 April 2012 to 4 October 2017) to develop the clinical prediction models based on logistic regression analyses. The development models were internally validated using bootstrapping and shrinkage before temporal external validation was performed using 464 hip arthroscopy patients (surgery performed 5 October 2017 to 13 May 2019).

RESULTS

The prediction model for unsuccessful outcomes showed best and acceptable predictive performance on the external validation dataset for all multiple imputations (Nagelkerke R2 range: 0.25-0.26) and calibration (intercept range: -0.10 to -0.11; slope range: 1.06-1.09), and acceptable discrimination (area under the curve range: 0.76-0.77). The prediction model for successful outcomes did not calibrate well, while also showing poor discrimination.

CONCLUSION

Common clinical variables including demographics, radiographic parameters of hip morphology and self-reported measures were able to predict the probability of having an unsuccessful outcome 1 year after hip arthroscopy, while the model for successful outcome showed unacceptable accuracy. The externally validated prediction model can be used to support clinical evaluation and shared decision making by informing the orthopaedic surgeon and patient about the risk of an unsuccessful outcome, and thus when surgery may not be appropriate.

A three-dimensional (3D) printed simulator as a feasible assessment tool for evaluating hip arthroscopy skills

PURPOSE

The aims of this study were (1) to develop a three-dimensional (3D) printed simulator that facilitates the simulation of surgical skills for portal placement, intra-articular identification of anatomical structures and arthroscope navigation for hip arthroscopy and (2) to concurrently examine the feasibility of using this simulator as an assessment tool to evaluate trainees' surgical competencies.

METHODS

A simulator was developed using a combination of medical imaging, computer-aided design, and 3D printing. A cross-sectional study was conducted with 29 participants divided into 3 subgroups (novice, intermediate and experienced). All participants performed related skills on the simulator, and their performance was evaluated using different assessment parameters. The participants' qualitative feedback regarding the simulator was also collected. The data collated from each group of participants were subsequently compared.

RESULTS

Significant differences were observed between the three subgroups of participants with regard to the total checklist score (F_2,26 = 11.3), total Arthroscopic Surgical Skill Evaluation score (F_2,26 = 92.1), overall final global rating scale score (F_2,26 = 49), number of times the participants used fluoroscopy (F_2,26 = 7.4), and task completion times (F_2,26 = 23.5). The participants' performance in the simulated operation was correlated with their prior clinical experience. There was mainly positive feedback with regard to the fidelity and utility of the simulator in relation to the surgeons' prior clinical experience.

CONCLUSIONS

This study demonstrated that a reliable hip arthroscopic simulator can be developed for use by orthopedic surgeons to evaluate their hip arthroscopic skills before performing actual surgical operations.

LEVEL OF EVIDENCE

Level III.

Limited clinical utility of a machine learning revision prediction model based on a national hip arthroscopy registry

PURPOSE

Accurate prediction of outcome following hip arthroscopy is challenging and machine learning has the potential to improve our predictive capability. The purpose of this study was to determine if machine learning analysis of the Danish Hip Arthroscopy Registry (DHAR) can develop a clinically meaningful calculator for predicting the probability of a patient undergoing subsequent revision surgery following primary hip arthroscopy.

METHODS

Machine learning analysis was performed on the DHAR. The primary outcome for the models was probability of revision hip arthroscopy within 1, 2, and/or 5 years after primary hip arthroscopy. Data were split randomly into training (75%) and test (25%) sets. Four models intended for these types of data were tested: Cox elastic net, random survival forest, gradient boosted regression (GBM), and super learner. These four models represent a range of approaches to statistical details like variable selection and model complexity. Model performance was assessed by calculating calibration and area under the curve (AUC). Analysis was performed using only variables available in the pre-operative clinical setting and then repeated to compare model performance using all variables available in the registry.

RESULTS

In total, 5581 patients were included for analysis. Average follow-up time or time-to-revision was 4.25 years (± 2.51) years and overall revision rate was 11%. All four models were generally well calibrated and demonstrated concordance in the moderate range when restricted to only pre-operative variables (0.62-0.67), and when considering all variables available in the registry (0.63-0.66). The 95% confidence intervals for model concordance were wide for both analyses, ranging from a low of 0.53 to a high of 0.75, indicating uncertainty about the true accuracy of the models.

CONCLUSION

The association between pre-surgical factors and outcome following hip arthroscopy is complex. Machine learning analysis of the DHAR produced a model capable of predicting revision surgery risk following primary hip arthroscopy that demonstrated moderate accuracy but likely limited clinical usefulness. Prediction accuracy would benefit from enhanced data quality within the registry and this preliminary study holds promise for future model generation as the DHAR matures. Ongoing collection of high-quality data by the DHAR should enable improved patient-specific outcome prediction that is generalisable across the population.

LEVEL OF EVIDENCE

Level III.

[Persistent or recurrent symptoms after surgery for femoroacetabular impingement syndrome (FAIS) : Pathology, diagnostics and therapy]

BACKGROUND

Femoroacetabular impingement syndrome (FAIS) has gained vast importance in the last two decades. Multiple studies have shown that if untreated, early osteoarthritis of the hip joint may result. Hip arthroscopy is one of the fastest growing procedures in the orthopedic cosmos, having already replaced the majority of (mini) open techniques in FAIS surgery. However, with the recent remarkable increase in the volume of hip arthroscopies performed worldwide, the number of patients with persistent or recurrent symptoms after FAIS surgery is also growing.

PATHOLOGY

Potential underlying pathologies are misresection of the bony deformity, insufficiency fracture of the femoral head neck junction or the femoral subchondral head itself (SIFFH), adhesions, failed chondrolabral or capsular treatment, septic arthritis, heterotopic ossification or a wrong indication in the case of osteoarthritis that is already too advanced. Most of these occur more often during the extensive learning curve for hip arthroscopy.

DIAGNOSTICS

High-quality imaging plays a key role in determining the need for revision surgery vs. further conservative treatment. Therapeutical avenues are shown with the common goal of proper detection and correction of the underlying pathology to address unsatisfactory FAIS treatment outcomes and ensure long-term survival of the native hip joint.

Revision Hip Arthroscopy With Labral Reconstruction for Irreparable Labral Tears in Athletes: Minimum 2-Year Outcomes With a Benchmark Control Group

BACKGROUND

The incidence of revision hip arthroscopy with labral reconstruction in athletes is increasing. However, the outcomes of revision hip arthroscopy with labral reconstruction in athletes have not been well established.

PURPOSES

(1) To report minimum 2-year patient-reported outcome (PRO) scores and return to sports (RTS) characteristics for high-level athletes undergoing revision hip arthroscopy with labral reconstruction and (2) to compare clinical results with those of a propensity-matched control group of high-level athletes undergoing revision hip arthroscopy with labral repair.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data were prospectively collected and retrospectively reviewed for athletes at any level who underwent a revision hip arthroscopy and a labral reconstruction between April 2010 and March 2019. Minimum 2-year PROs were reported for the modified Harris Hip Score (mHHS), the Nonarthritic Hip Score (NAHS), the Hip Outcome Score-Sport Specific Subscale (HOS-SSS), the visual analog scale (VAS) for pain, and RTS. The percentages of athletes achieving the minimal clinically important difference (MCID) and the maximum outcome improvement satisfaction threshold (MOIST) were also recorded. These patients were propensity matched in a 1: 1 ratio to athletes undergoing revision hip arthroscopy with labral repair for comparison.

RESULTS

A total of 46 athletes (N = 47 hips) were reported from 50 (n = 51 hips) athletes who underwent revision with labral reconstruction. A subanalysis of 30 propensity-matched athletes undergoing revision labral reconstruction was performed, with a mean follow-up time of 26.3 ± 2.4 months and an age of 28.5 ± 10.1 years, and compared with a revision labral repair group. Significant improvements were obtained for the mHHS, the NAHS, the HOS-SSS, and the VAS from preoperative to the latest follow-up (P < .001), with an achievement MCID rate of 61.5%, 72%, 62.5%, and 76.9% for the mHHS, the NAHS, the HOS-SSS, and the VAS, respectively. The rate for re-revision surgery (2 tertiary arthroscopy and 1 conversion to total hip arthroplasty) was 10%, and 14 patients (63.6%) were able to RTS. Improvements in PROs, rates of achieving MCID/MOIST, rate of re-revision surgery (re-revision hip arthroscopy, P = .671; conversion to total hip arthroplasty, P > .999), and RTS rate (P = .337) were similar when compared with those of the propensity-matched control labral repair group (P > .05).

CONCLUSION

Revision hip arthroscopy with labral reconstruction, in the context of an irreparable labral tear, seems to be a valid treatment option in the athletic population, demonstrating significant improvements in all PROs and low rates of undergoing revision surgery. Athletes experienced a similar magnitude of improvement in PROs, RTS rate, and revision surgery rate to that of a propensity-matched control group of athletes undergoing revision hip arthroscopy with labral repair.

Five-Year Follow-up After Hip Arthroscopic Surgery in the Horsens-Aarhus Femoroacetabular Impingement (HAFAI) Cohort

Background:

Patients with femoroacetabular impingement syndrome (FAIS) are offered hip arthroscopic surgery to decrease hip pain, improve their function, and decrease development of hip osteoarthritis (OA). Nonetheless, long-term follow-up data are few.

Purpose:

To investigate patient-reported outcomes, clinical tests, reoperations, and radiographic status 5 years after primary hip arthroscopy in patients with FAIS.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 60 patients (age, 36 ± 9 years; 63% female) diagnosed with FAIS were included in the study and followed for 5 years after hip arthroscopy. Follow-up included Copenhagen Hip and Groin Outcome Score (HAGOS); Hip Sports Activity Scale; and clinical tests (flexion, adduction, internal rotation [FADIR]; flexion, abduction, external rotation [FABER]; and psoas muscle/tendon major pain provocation). Radiographic evaluation included lateral joint-space width (LJSW) and Tönnis classification for hip OA. Reoperations and conversion to total hip replacement (THR) were recorded. We calculated the proportion of patients who exceeded the minimal important change (MIC), achieved the Patient Acceptable Symptom State (PASS), and were within the 95% reference interval of age- and sex-matched persons with no hip problems. Changes were investigated using paired t tests.

Results:

Compared with preoperatively, all HAGOS subscales were improved substantially 5 years after surgery (mean, ≥21 points; P < .001), and 67% to 89% of patients reported improvements exceeding MIC. Between 56% and 80% achieved PASS, but only 7% to 24% reached the 95% reference interval for the HAGOS subscales. A total of 36% had a positive FADIR test and 25% had a positive FABER test, which were improvements compared with preoperatively (P < .001 for both). Patients with a positive FADIR test had significantly worse HAGOS subscales. Six patients (10%) had a THR since their primary hip arthroscopy. In the remaining patients, the mean LJSW was decreased (-0.4 mm; P = .043), and hip OA had worsened in 9 patients (23%; P = .003).

Conclusion:

Five years after surgery, the majority of patients experienced HAGOS improvements exceeding MIC while also showing an acceptable PASS. However, clinical tests, participation in physical activities, and quality of life indicated that many patients still experience hip problems.

Registration:

NCT04590924 (ClinicalTrials.gov identifier).

Acetabular labral tear is associated with high pelvic incidence with or without femoroacetabular impingement morphology

PURPOSE

The aim of this study was to investigate the association between pelvic sagittal parameters and acetabular labral tears.

METHODS

Three-hundred and sixty-five patients (449 hips) who underwent magnetic resonance imaging (MRI) or magnetic resonance arthrogram (MRA) for hip pain were enrolled in this study. Pelvic sagittal parameters, including the pelvic incidence, pelvic tilt, and sacral slope, were measured with a standing lumbosacral lateral radiograph. All subjects were divided into two groups according to the presence or absence of radiologic acetabular labral tears and compared. Furthermore, the two groups were divided into subgroups according to whether femoroacetabular impingement (FAI) morphology was present or not and compared.

RESULTS

Pelvic incidence was greater in the labral tear group than in the non-labral tear group (52.3° ± 8.2° versus 47.1° ± 6.8°, p < 0.001). After accounting for potentially confounding variables, we found that higher age (odds ratio 1.04, 95% confidence interval [CI] 1.02 to 1.06, p = 0.001), FAI (odds ratio 15.11, 95% CI 7.43 to 30.75, p < 0.001), and high pelvic incidence (odds ratio 1.13, 95% CI 1.09 to 1.17, p < 0.001) were independently associated with acetabular labral tear. When only the patients without FAI (308 hips) were divided into groups with and without acetabular labral tear, we found that higher age (odds ratio 1.03, 95% CI 1.01 to 1.06, p = 0.008) and high pelvic incidence (odds ratio 1.15, 95% CI 1.11 to 1.19, p < 0.001) were independently associated with acetabular labral tear.

CONCLUSION

Acetabular labral tear is associated with high pelvic incidence with or without FAI morphology.

LEVEL OF EVIDENCE

III.

High prevalence of hip lesions secondary to arthroscopic over- or undercorrection of femoroacetabular impingement in patients with postoperative pain

Objectives

To compare the prevalence of pre- and postoperative osseous deformities and intra-articular lesions in patients with persistent pain following arthroscopic femoroacetabular impingement (FAI) correction and to identify imaging findings associated with progressive cartilage damage.

Methods

Retrospective study evaluating patients with hip pain following arthroscopic FAI correction between 2010 and 2018. Pre- and postoperative imaging studies were analyzed independently by two blinded readers for osseous deformities (cam-deformity, hip dysplasia, acetabular overcoverage, femoral torsion) and intra-articular lesions (chondro-labral damage, capsular lesions). Prevalence of osseous deformities and intra-articular lesions was compared with paired t-tests/McNemar tests for continuous/dichotomous data. Association between imaging findings and progressive cartilage damage was assessed with logistic regression.

Results

Forty-six patients (mean age 29 ± 10 years; 30 female) were included. Postoperatively, 74% (34/46) of patients had any osseous deformity including 48% (22/46) acetabular and femoral deformities. Ninety-six percent (44/46) had an intra-articular lesion ranging from 20% (9/46) for femoral to 65% (30/46) for acetabular cartilage lesions. Prevalence of hip dysplasia increased (2 to 20%, p = 0.01) from pre- to postoperatively while prevalence of cam-deformity decreased (83 to 28%, p < 0.001).

Progressive cartilage damage was detected in 37% (17/46) of patients and was associated with extensive preoperative cartilage damage > 2 h, i.e., > 60° (OR 7.72; p = 0.02) and an incremental increase in postoperative alpha angles (OR 1.18; p = 0.04).

Conclusion

Prevalence of osseous deformities secondary to over- or undercorrrection was high. Extensive preoperative cartilage damage and higher postoperative alpha angles increase the risk for progressive degeneration.

Key Points

• The majority of patients presented with osseous deformities of the acetabulum or femur (74%) and with intra-articular lesions (96%) on postoperative imaging.

• Prevalence of hip dysplasia increased (2 to 20%, p = 0.01) from pre- to postoperatively while prevalence of a cam deformity decreased (83 to 28%, p < 0.001).

• Progressive cartilage damage was present in 37% of patients and was associated with extensive preoperative cartilage damage > 2 h (OR 7.72; p = 0.02) and with an incremental increase in postoperative alpha angles (OR 1.18; p = 0.04).

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08398-4.

Revision Hip Arthroscopy in High-Level Athletes: Minimum 2-Year Outcomes Comparison to a Propensity-Matched Primary Hip Arthroscopy Control Group

BACKGROUND

Outcomes of revision hip arthroscopy in the athletic population have not been well established.

PURPOSE

(1) To report clinical outcomes for high-level athletes undergoing revision hip arthroscopy in the setting of femoroacetabular impingement syndrome (FAIS) or labral tears and (2) to compare these outcomes against a propensity-matched group of high-level athletes undergoing primary hip arthroscopy.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data for professional, college, and high school athletes were prospectively collected and retrospectively reviewed between January 2012 and October 2018. Patients were included if they underwent revision or primary hip arthroscopy and had preoperative and minimum 2-year patient-reported outcome (PRO) scores for modified Harris Hip Score (mHHS), Non-Arthritic Hip Score (NAHS), Hip Outcome Score Sports-Specific Subscale (HOS-SSS), and visual analog scale (VAS) for pain. The findings and outcomes of revision athletes were compared with a propensity-matched control group of high-level athletes undergoing primary hip arthroscopy.

RESULTS

A total of 32 hips (29 patients) undergoing revision hip arthroscopy and 92 hips (88 patients) undergoing primary hip arthroscopy were included in our final analysis with a median follow-up time of 29.5 months (95% CI, 27.2-32.1 months) and 36.5 months (95% CI, 33.5-37.7 months), respectively. Athletes undergoing revision surgery showed significant improvement in all recorded PRO measurements and achieved patient acceptable symptomatic state (PASS) and minimal clinically important difference (MCID) for mHHS at high rates (80.6% and 83.9%, respectively). When compared with a propensity-matched primary control group, patients undergoing revision surgery demonstrated lower preoperative and postoperative scores for mHHS, NAHS, and HOS-SSS, but the magnitude of improvement in functional scores was similar between groups. Athletes undergoing revision surgery achieved PASS for HOS-SSS at lower rates than the control group (P = .005), and they were less likely to attempt to return to sport compared with the control group (62.5% vs 87.0%; P < .01).

CONCLUSION

Revision hip arthroscopy is a viable treatment option to improve PROs in high-level athletes at minimum 2-year follow-up. The study group showed significant improvement in functional scores and a high rate of successful outcomes. They experienced similar magnitude of improvement as that of a propensity-matched control group; however, they achieved lower postoperative PRO scores and attempted to return to sport at lower rates.

Predicting the Risk of Subsequent Hip Surgery Before Primary Hip Arthroscopy for Femoroacetabular Impingement Syndrome: A Machine Learning Analysis of Preoperative Risk Factors in Hip Preservation

BACKGROUND

The number of patients requiring reoperation has increased as the volume of hip arthroscopy for femoroacetabular impingement syndrome (FAIS) has increased. The factors most important in determining patients who are likely to require reoperation remain elusive.

PURPOSE

To leverage machine learning to better characterize the complex relationship across various preoperative factors (patient characteristics, radiographic parameters, patient-reported outcome measures [PROMs]) for patients undergoing primary hip arthroscopy for FAIS to determine which features predict the need for future ipsilateral hip reoperation, namely, revision hip arthroscopy, total hip arthroplasty (THA), hip resurfacing arthroplasty (HRA), or periacetabular osteotomy (PAO).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A cohort of 3147 patients undergoing 3748 primary hip arthroscopy procedures were included from an institutional hip preservation registry. Preoperative computed tomography of the hip was obtained for each patient, from which the following parameters were calculated: the alpha angle; the coronal center-edge angle; the neck-shaft angle; the acetabular version angle at 1, 2, and 3 o'clock; and the femoral version angle. Preoperative PROMs included the modified Harris Hip Score (mHHS), the Hip Outcome Score (HOS)-Activities of Daily Living subscale (HOS-ADL) and the Sport Specific subscale, and the international Hip Outcome Tool (iHOT-33). Random forest models were created for revision hip arthroscopy, the THA, the HRA, and the PAO. Area under the curve (AUC) for the receiver operating characteristic curve and accuracy were calculated to evaluate each model.

RESULTS

A total of 171 patients (4.6%) underwent subsequent hip surgery after primary hip arthroscopy for FAIS. The AUC and accuracy, respectively, were 0.77 (fair) and 76% for revision hip arthroscopy (mean, 26.4-month follow-up); 0.80 (good) and 81% for THA (mean, 32.5-month follow-up); 0.62 (poor) and 69% for HRA (mean, 45.4-month follow-up); and 0.76 (fair) and 74% for PAO (mean, 30.4-month follow-up). The most important factors in predicting reoperation after primary hip arthroscopy were higher body mass index (BMI) and lower preoperative HOS-ADL for revision hip arthroscopy, greater age and lower preoperative iHOT-33 for THA, increased BMI for HRA, and larger neck-shaft angle and lower preoperative mHHS for PAO.

CONCLUSION

Despite the low failure rate of hip arthroscopy for FAIS, our study demonstrated that machine learning has the capability to identify key preoperative risk factors that may predict subsequent ipsilateral hip surgery before the index hip arthroscopy. Knowledge of these demographic, radiographic, and patient-reported outcome data may aid in preoperative counseling and expectation management to better optimize hip preservation.

Obesity is associated with less favorable outcomes following hip arthroscopic surgery: a systematic review and meta-analysis

PURPOSE

The aim of this study was to systematically review the existing literature comparing the postoperative outcomes after following hip arthroscopy in obese and non-obese patients.

METHODS

Studies comparing the outcomes following hip arthroscopy of obese and non-obese patients were systematically identified via a computer-assisted literature search of Pubmed (Medline), EMBASE, and Cochrane Library using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Studies comparing the outcome of hip arthroscopy in different body mass index (BMI) groups were included. Data including patient-reported outcome measures (PROMs), revision arthroscopy rate, conversion rate to total hip arthroplasty (THA), and complications were collected. The methodological index for non-randomized studies (MINORS) and Newcastle-Ottawa Scale (NOS) were used to assess the quality of each study quality. The effect of heterogeneity was quantified by calculating the I² value.

RESULTS

A total of eight studies were finally included in the qualitative analysis, and three studies of high quality involving 373 hips were included in the quantitative assessment. All the studies defined obesity as a BMI of  ≥ 30 kg/m². The modified Harris Hip Score and the Non-Arthritic Hip Score were 5.1 (95% CI 1.1-9.1) and 9.0 (95% CI 5.0-13.1) points lower, respectively, in the obese group than in the non-obese group. The pooled odds ratios were 1.2 (95% CI 0.5-2.7) for revision arthroscopy, 2.4 (95% CI 1.3-4.6) for conversion to THA, and 3.2 (95% CI 1.2-8.6 for complications in favor of the non-obese group. The heterogeneity was low in all outcome assessments (I² 0-18%).

CONCLUSION

Obese patients had significantly lower PROMs than non-obese patients following hip arthroscopic surgery, and the THA conversion and complication rates were 2.4 times and 3.2 times higher, respectively. Understanding the effect of obesity on hip arthroscopy will allow appropriate surgical indications for surgery to be further refined and help obese patients to understand their individual risk profile.

LEVEL OF EVIDENCE

Systematic review of Level III-IV studies, Level IV.