The aim of this study was to determine the accuracy of registration and the precision of the resection volume in navigated hip arthroscopy for cam-type femoroacetabular impingement, using imageless and image-based registration. A virtual cam lesion was defined in 12 paired cadaver hips and randomly assigned to either imageless or image-based (three-dimensional (3D) fluoroscopy) navigated arthroscopic head–neck osteochondroplasty. The accuracy of patient–image registration for both protocols was evaluated and post-operative imaging was performed to evaluate the accuracy of the surgical resection. We found that the estimated accuracy of imageless registration in the arthroscopic setting was poor, with a mean error of 5.6 mm (standard deviation (sd) 4.08; 95% confidence interval (CI) 4.14 to 7.19). Because of the significant mismatch between the actual position of the probe during surgery and the position of that probe as displayed on the navigation platform screen, navigated femoral osteochondroplasty was physically impossible. The estimated accuracy of image-based registration by means of 3D fluoroscopy had a mean error of 0.8 mm (sd 0.51; 95% CI 0.56 to 0.94). In terms of the volume of bony resection, a mean of 17% (sd 11; -6% to 28%) more bone was resected than with the virtual plan (p = 0.02). The resection was a mean of 1 mm deeper (sd 0.7; -0.3 to 1.6) larger than on the original virtual plan (p = 0.02).

In conclusion, given the limited femoral surface that can be reached and digitised during arthroscopy of the hip, imageless registration is inaccurate and does not allow for reliable surgical navigation. However, image-based registration does acceptably allow for guided femoral osteochondroplasty in the arthroscopic management of femoroacetabular impingement.

Background. Elite performance has tremendous physical demands and places elite athletes at an increased risk of sustaining a variety of orthopaedic injuries (1–4). Pain around the hip is common in high-level athletes representing up to 6% of all athletic injuries (5–7). Expedient diagnosis and effective treatment are paramount for their future sporting careers and to prevent subsequent joint degeneration. The purpose of this systematic review was to evaluate the outcome and the rate of return to play (RTP) following hip arthroscopy in elite athletes. Methods. A computer-based systematic search followed the PRISMA Guidelines (8) was performed using the 6 most comprehensive databases (CENTRAL, PUBMED, EMBASE, SCOPUS, EBSCO, Google Scholar and Web of Science) and included all published studies from inception until November 1. st. 2018. Weighted means were calculated for the rate of RTP and duration and for patient reported outcome measures (PROMs). Results. After eligibility screening, 17 articles were included with a total of 736 male and seven female patients, 761 hips and a mean age of 27.9±3.6 years. The mean follow-up period was 35.8±13.4 months and 17.1±12.3% of athletes had undergone bilateral hip arthroscopies. Overall, 93.9% (95% CI: 90.5, 96.6, P < 0.0001) of patients demonstrated return to sport after 6.7±2.5 months post-surgery and all PROMs improved post-operatively. During follow-up, 9.6% (95% CI: 5.2, 15.2, P = 0.025) patients needed further intervention. Conclusion. A high percentage of elite athletes return to the same level of competition after hip arthroscopy, with a low rate of further interventions. Hip arthroscopy appears to be an efficacious treatment for elite athletes suffering for hip and/or groin pain