Intraoperative Computer Vision Integrated Interactive Fluoroscopy Correlates With Successful Femoroplasty on Clinic-Based Radiographs

Computer-Assisted Arthroscopic Cam Resection

Determining the appropriate femoral cam resection during hip arthroscopy for femoroacetabular impingement syndrome is both critical for the patient and challenging for the surgeon. Incomplete bone resection is a leading cause of failed hip arthroscopy, whereas over-resection may increase the risk of femoral neck fracture. The alpha angle is a validated 2-dimensional radiographic measurement used to both diagnose femoroacetabular impingement syndrome preoperatively and to determine resection adequacy postoperatively. Computer-assisted intraoperative guidance systems enhance the accuracy of femoral cam resection, although a preoperative 3-dimensional computed tomography scan may be required. Other systems, such as the HipCheck software (Stryker, Kalamazoo, MI), have been developed to provide intraoperative guidance with live feedback using simultaneous alpha angle measurements overlayed on fluoroscopic images without the requirement for routine preoperative computed tomography. Via intraoperative touchscreen navigation, the surgeon identifies the midpoint of the femoral neck and femoral head. A commercial software program provides real-time alpha angle measurements, as well as enhanced visualization of the femoral cam deformity with an adjustable resection curve. Before the surgeon performs the cam resection, the software provides a template for appropriate resection depth in 6 positions of the hip. Upon completion of the femoral cam resection, the hip is again assessed in the same 6 positions and the alpha angle is assessed to ensure a complete resection.

Young Bovine Hip Model for Hip Arthroscopy Training

Hip arthroscopy is associated with risks for complications, especially for novice surgeons. The present article reports use of a young bovine hip as a valid educational tool for key components of arthroscopic treatment of femoroacetabular impingement syndrome, ie, labrum repair and cam excision. The purpose of this Technical Note is to describe the steps of arthroscopic femoroacetabular impingement treatment in the bovine hip.

The Circumferential Femoroplasty: An All-Arthroscopic Technique for Addressing a Challenging Hip Deformity

Femoroacetabular impingement is recognized as a common cause of hip pain. Cam-type femoroacetabular impingement results from abnormal contact between an aspherical femoral head and the acetabular rim during hip range of motion, leading to labral tearing, cartilage damage, and, eventually, osteoarthritis. Arthroscopic correction of this bony deformity has been well described, particularly in the anterolateral quadrant of the femoral neck. Some deformities extend well beyond this quadrant, involving most or all of the circumference of the femoral neck, making arthroscopic decompression a challenge. We present a post-less, all-arthroscopic technique for performing a circumferential cam decompression using 3-dimensional preoperative planning software and interactive fluoroscopy-integrated computer vision interface.

Postoperative Alpha Angle Is Predictive of Return to Sport in Athletes Undergoing Hip Arthroscopy for Femoroacetabular Impingement

PURPOSE

To identify clinical and radiographic factors that predict return to sport in athletes undergoing hip arthroscopy and to determine thresholds for significant predictors.

METHODS

Data were reviewed on all patients who underwent primary hip arthroscopy between November 2008 and August 2018. Patients were included if they played professional, college, or high school sports within 1 year before surgery and had preoperative, 3-month, 1-year, and 2-year postoperative patient-reported outcome scores for modified Harris Hip Score, Hip Outcome Score-Sport Specific-Subscale, and Nonarthritic Hip Score. Rates of achieving the minimal clinically important difference also were evaluated. Patients were divided into groups based on whether they returned to sport at the same or greater level. Multivariate logistic regression and receiver operator characteristic analysis were used to evaluate the correlation between significant variables and return to sport.

RESULTS

A total of 136 patients with a mean age of 20.8 ± 7.07 years were included. Among athletes who attempted to return, professional and collegiate athletes returned to sport at any level at a rate of 85.0% (51/60), and high-school athletes returned at a rate of 88.1% (52/59). Competition level, postoperative alpha angle, change in alpha angle, and postoperative patient-reported outcomes were significantly different between groups. Athletes who returned to sport achieved the minimal clinically important difference for Hip Outcome Score-Sport Specific-Subscale at significantly higher rates than athletes who did not return to sport (91.6% vs 71.7%, P = .002, S = 8.97). The multivariate logistic regression model identified postoperative alpha angle as a statistically significant predictor of return to sport (P < .001, S > 9.97 [odds ratio 0.85, 95% confidence interval 0.79-0.91]). The receiver operator characteristic curve for postoperative alpha angle demonstrated acceptable discrimination between patients returning to sport and patients not returning to sport with an area under the curve of 0.71 and a threshold value of 46°. Athletes with a postoperative alpha angle ≤46° returned to sport at significantly higher rates than those with a postoperative alpha angle >46° [(P < .001, S > 9.97 [odds ratio 6.3, 95% confidence interval 2.6-15.2]).

CONCLUSIONS

Postoperative alpha angle was identified as a predictor of return to sport in athletes. The odds of returning to sport were 6.3 times greater in athletes with postoperative alpha angles ≤46° compared with athletes with angles >46°.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Editorial Commentary: Assistive Technologies for Hip Arthroscopic Cam Resection Will Improve Diagnostic and Surgical Accuracy: Desperately Needed and Here to Stay

Hip arthroscopy is technically demanding and presents a steep learning curve. Joint access and maneuverability of surgical tools are impeded by a large soft-tissue envelope. Furthermore, cam resection is challenging owing to the small size of the lesion and the difficulty in delineating what is normal and where the cam starts. Thus, the number of incomplete resections is high and represents the bulk of indications for revision hip arthroscopy. The search for assistive technologies to improve on diagnostics and surgical accuracy is consequently substantial and unquestionably needed. Intraoperative feedback will improve our resection accuracy while decreasing the learning efforts of both expert and novice surgeons.