Introduction 5 1 29 29 1 8 27 15 25 6 26 23 24 1 10 1 7 13 2 28 Methods Patient selection 14 1 1 Table 1 Pre-operative sports activities of the 45 professional athletes Sport No. of patients Hockey 24 Golf 6 Football 5 Soccer 3 Dance 2 Baseball 2 Martial arts 1 Tennis 1 Jockey 1 Total 45 Arthroscopic procedure 3 12 28 22 9 11 12 22 12 18 18 28 In general, the above-described procedure took approximately 2–3 h, depending on the degree of labral and chondral pathology. Traction time was limited to less than 2 h to reduce the risk of neurovascular compromise. Post-operative management Post-operative medical prophylaxis included an aspirin or a low-molecular weight heparin, a non-steroidal anti-inflammatory, and an antibiotic. Each of the 45 athletes underwent post-operative rehabilitation according to the following generalized protocol that was devised based on personal experience. For basic procedures involving decompression of FAI and labral treatment, weightbearing was restricted to 20 pounds, flatfoot for 4 weeks. A brace was prescribed to be worn for 10 days to protect the hip and limit abduction and rotation. Continuous passive motion (CPM) was used to apply 0–90 degrees of hip flexion for up to 8 h per day for 4 weeks. Night boots were worn for ten post-operative days to limit rotation during sleep. If capsular modification procedures (thermal capsulorrhaphy or capsular plication) were performed, rotation precautions were extended for a total of 21 days to avoid capsular stress. If microfracture was performed, weightbearing restrictions and CPM use were extended for a total of 8 weeks. Physical therapy exercises were implemented within four post-operative hours. It is our belief, based on clinical observation, that this, in addition to an early emphasis on passive hip motion (particularly internal rotation) reduces the incidence of adhesion formation. Active hip flexion was limited for 4 weeks, based on clinical observation, to minimize the risk of hip flexor tendonitis. Athletes were typically allowed to return to full competitive activity between 12 and 16 post-operative weeks. Return-to-play statistics were determined by retrospective chart review and personal follow-up communication with the athletes. Results The average age of the athletes at the time of surgery was 31 years (range: 17–61). Eleven athletes (24%) previously underwent hip arthroscopy by multiple primary surgeons for the treatment of labral and chondral pathologies and experienced a recurrence of hip symptoms. The average time to follow-up was 1.6 years (range: 6 months to 5.5 years). Twenty-two athletes (49%) were treated for an isolated cam lesion and three athletes (7%) were treated for an isolated pincer lesion. Twenty-one athletes (47%) had a mixed pathology of both cam and pincer lesions. All of the athletes had acetabular labral tears. Twenty-five patients (56%) underwent either labral repair or re-fixation following rim trimming with suture anchors (average 1.3 anchors per patient, range: 1–3). Twelve patients (27%) had intra-substance labral repair. Five patients had labral debridement; one patient had a detached tear, one had frayed labral tissue, and three patients had complex tears consisting of detached, frayed, and flap components. Two patients were labral deficient from a previous arthroscopic debridement. They underwent labral grafting using an iliotibial band autograft. Twenty-one patients (47%) had a grade IV acetabular chondral defect; 14 underwent arthroscopic microfracture, 5 underwent thermal chondroplasty, and 2 patients had no treatment due to the diffuseness of their disease. Three patients (7%) had a grade IV femoral head chondral defect; one was treated with microfracture, one with chondroplasty, and one patient had no treatment due to the diffuseness of his disease. Seventeen (38%) had a grade I–III acetabular chondral defect (13 treated with chondroplasty and 1 treated with microfracture) and 11 (24%) had a grade I–III femoral head chondral defect (all 11 were treated with chondroplasty). Four patients (one baseball player, one football player, one hockey player and 1 golfer) had extensive diffuse OA at the time of arthroscopy, but opted to delay arthroplasty. Twenty-six patients (58%) had a partial tear of the ligamentum teres and 3 patients (7%) had a complete ligamentum teres avulsion. Thirteen (29%) patients underwent thermal capsulorrhaphy and 9 (20%) underwent plication for capsular redundancy. Seventeen patients (38%) had loose bodies in the joint and two patients required excision of myositis ossificans of the rectus femoris. Three patients (7%) underwent cheilectomy of a stenotic cotyloid fossa and 9 patients (20%) underwent arthroscopic release of a tight iliopsoas. 1 1 2 2 Fig. 1 a b FH Ac c Ac d  Fig. 2 a b Ac c L d e  Forty-two athletes (93%) returned to professional sport following hip arthroscopy. Three players (1 football player, 1 hockey player, and 1 baseball player) did not return to play following arthroscopy. Each of these patients had diffuse osteoarthritis at the time of arthroscopy. Five athletes (11%) required re-operation. Three underwent lysis of adhesions and two had symptomatic treatment of extensive osteoarthritis. All of the patients who underwent revision surgery for lysis of adhesions returned to professional play and the two with extensive osteoarthritis did not return to play. Thirty-five of the 45 athletes (78%) remained active at the professional level at an average of 1.6 years after hip arthroscopy. Discussion 19 21 29 1 2 8 13 7 2 4 17 19 20 20 17 4 4 1 29 28 16 A limitation of this study was the inherent selection bias involved with the study of professional athletes. This patient sub-group was financially motivated to return to play and may have been less likely to report post-operative symptoms and complications than the rest of patients treated for FAI. Despite this, we believed that a return-to-play analysis was critical to assess the outcomes of FAI treatment in a high-demand population. This cohort of professional athletes was debilitated prior to hip arthroscopy, and following intervention, was able to perform in physically intense professional sport activities. Also, the athletes’ precise reason for retirement and whether it was related to their hip injuries was difficult to discern. For this reason, given the relatively short span of all professional athletes’ careers, we chose to include all athletes at a minimum of 6 months post-operative. This time period was selected as an ample time period for completion of post-operative rehabilitation and return to sport. Another limitation of this study was the lack of follow-up subjective and objective data. Current outcomes instruments (modified Harris Hip score and the Non-Arthritic hip score) have not been validated for use in high-level athletes. It is our belief that these scoring systems fail to address the activities that are most limiting to athletes, and hence, underestimate the degree of debilitation in professional athletes. Evaluating the applicability of current scoring systems in athletes, and developing new outcomes instruments for athletes will be the focus of future studies. Other limitations of this study included unequal distribution of gender (42 males and 3 females) and professional sports. Because different sports place different demands on the hip, we cannot draw conclusions among the various sports. The arthroscopic treatment of FAI represents the evolution of hip arthroscopy. In the past, soft tissue pathologies were treated in isolation, without addressing underlying impinging osseous abnormalities. Recent developments, particularly by Ganz and colleagues, have enlightened us to the pathology of FAI and the associated treatment options. In order to treat high-demand patients with FAI, an arthroscopic technique was developed. This study has demonstrated that full return to professional competitive sport is possible following arthroscopic treatment of FAI. Additional studies are needed to determine the effect on long-term joint degeneration of early surgical intervention to treat FAI.