Femoroacetabular impingement and associated labral tearing is a common source of hip pain in athletes. This article reviews the hip joint anatomy and complex interplay between alterations on the femoral and acetabular sides, in addition to evaluation of soft tissue stabilizers and spinopelvic parameters. Symptom management with a focus on arthroscopic treatment of abnormal bony morphology and labral repair or reconstruction is discussed. In select patients with persistent pain who have failed conservative measures, hip arthroscopy with correction of bony impingement and labral repair or reconstruction has yielded good to excellent results in recreational and professional athletes.
Key points
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Femoroacetabular impingement can include altered bony morphology of the femoral head-neck junction (cam lesion), acetabular rim (pincer lesion), or both (mixed lesions). Restoring the labral seal is critical in restoring function and stability to the hip joint.
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A nonoperative treatment algorithm consisting of rest, nonsteroidal anti-inflammatory drugs, physical therapy, and consideration of a one-time image-guided intra-articular injection can successfully manage symptoms in many patients.
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It is critical to correct abnormal bony morphology in addition to treatment of labral pathology. We favor labral repair when enough competent tissue is available to restore the labral seal. Typically, reconstruction with allograft is preferred in a revision setting, for an ossified labrum, or if the labrum is irreparable.
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Correction of bony impingement and labral preservation techniques allow a high rate of RTP in recreational and elite athletes alike.
Introduction
The ball-in-socket articulation of the femoral head in the acetabulum is highly constrained, conferring stability from bony and soft tissue structures. Optimal function depends on sphericity of the femoral head, adequate (but not over) containment by the acetabulum, soft tissue stabilization, spinopelvic parameters, and neuromuscular integrity. Any conditions affecting these components can lead to hip impingement or instability, chondrolabral injury, and early joint degeneration.
The radius of curvature of the femoral head should hold constant until it increases at the transition to the femoral neck. The alpha angle, best measured on modified lateral hip radiographs (Dunn views) or advanced imaging, quantifies this point of transition ( Fig. 1 A, B ). A premature increase in the radius of curvature causes a nonspherical femoral head and thus the term cam lesion morphology. A cam lesion is the most common abnormality leading to femoroacetabular impingement (FAI) and subsequent acetabular labral tears. Cam lesion morphology is largely idiopathic; however, some recent evidence supports the development of these lesions during adolescence in response to repetitive stress on the open proximal femoral physis. Palmer and colleagues determined that sporting activity during adolescence is strongly associated with the development of cam morphology secondary to epiphyseal hypertrophy and extension with a dose-response relationship. Furthermore, males participating in competitive sport are at particularly elevated risk of developing cam morphology and secondary hip pathology. Childhood disease, such as epiphyseal dysplasias, slipped capital femoral epiphysis, Legg-Calvé-Perthes disease, inflammatory conditions, and post-traumatic malformation can also create secondary cam morphology. Other sources of femoral-sided (cam-type) impingement include coxa vara, femoral retroversion, and osteophyte formation.
On the acetabular side, the femoral head must be appropriately contained. Hip dysplasia describes undercontainment of the femoral head by the acetabulum and can lead to labral tearing from serial microinstability events. In contrast, pincer morphology describes a state of overcontainment of the femoral head by the acetabulum ( Fig. 1 C, D). This is from lateral and/or anterior overcoverage in the form of coxa profunda/protrusio, acetabular retroversion, prominence of the anterior inferior iliac spine, labral calcification, and osteophyte formation.
Static soft tissue stability is conferred to the hip joint by the acetabular labrum and joint capsule. The hip labrum is a horseshoe-shaped structure contiguous with the transverse acetabular ligament. In normal hip joint biomechanics, the labrum is crucial in retaining a layer of pressurized intra-articular fluid for joint lubrication and load support/distribution. Its seal around the femoral head is further regarded as contributing to hip stability through its suction effect. The labrum also has fibers aiding in hip proprioception. Although traumatic labral injury can occur in the absence of FAI secondary to hip dislocation or subluxation events, labral tears are most commonly a result of repetitive bony impingement causing stress and tearing. Iatrogenic causes of instability caused by capsulectomy, labral resection, or overresection of a cam or pincer lesion have also been described.
Spinopelvic parameters and muscular coordination impact the development of FAI and are often the target of physical therapy for this condition. Lumbar hyperlordosis, low pelvic tilt, and high sacral slope can create functional pincer impingement by rotating the acetabulum forward in relation to the femoral head, creating abutment during hip flexion. Similarly, muscular imbalance, joint contracture, and deconditioning exacerbate FAI by altering hip kinesthetics. Physical therapy for FAI and labral injury involves posture and gait training and core and kinetic chain strengthening and coordination, as described in other articles in this issue.
Given the comprehensive nature of the articles in this issue, the evaluation of the athlete with hip pain including patient presentation and physical examination have been thoroughly discussed. In addition, the interpretation of hip imaging and role for diagnostic and therapeutic injections has been covered. The diagnosis of the source of hip pain in the absence of arthritis is challenging, but a reproducible algorithm can make diagnosis and treatment more effective with improved patient outcomes. This article focuses on the management of FAI in the athlete with a suspected or documented labral tear including labral repair and reconstruction options, and discusses outcomes in this patient population.
Conservative management
Conservative treatment of FAI consisting of nonsteroidal anti-inflammatory drugs and conditioning to improve posture and gait mechanics is often successful for definitive management. Physical deconditioning, if present, should always be addressed before considering surgical intervention. Focused physical therapy for a minimum of 4 to 6 weeks is frequently efficacious, has limited downside, and can serve as effective prehabilitation before an arthroscopic procedure if pain and functional limitations persist. A single image-guided intra-articular injection (local anesthetic ± corticosteroid) is considered as a diagnostic and potentially therapeutic treatment option. At this time there continues to be limited evidence to support use of platelet-rich plasma, hyaluronic acid, or stem cell treatments for management of FAI or labral tears. Those patients that fail these conservative treatment measures and are deemed appropriate surgical candidates should be considered for hip arthroscopy. ,
Bony treatment
Osteoplasty of the femur and/or acetabulum to address cam and pincer morphology is critical in the setting of FAI and labral tears. This improves the kinematic conflict causing FAI and protects the labrum from reinjury. Care must be taken to balance the risk of revision surgery (with underresection) with fracture risk or loss of labral seal (overresection of cam), or iatrogenic instability and early hip degeneration (overresection of pincer). Use of intraoperative fluoroscopy or advanced imaging modalities is critical to avoid complications related to underresection or overresection of pincer and cam lesions.
Labral treatment
Operative Management: Debridement, Repair, or Reconstruction
Open versus arthroscopic treatment
Although Burman was the first to perform and describe hip arthroscopy in 1931, it would take more than 75 years for hip arthroscopy to blossom. As such, arthroscopic management of patients with FAI and labral tears that have failed conservative treatment measures continues to increase in popularity worldwide. Favorable results have been demonstrated using open and arthroscopic approaches to treat FAI and labral tears. Improved hip outcome score (HOS) sports subscale and higher nonarthritic hip scores at 2-year follow-up were observed in the arthroscopic cohort. Similarly, superior health-related quality of life score and trends toward faster recovery and return to sport have been shown with arthroscopic treatment of FAI and labral tears in studies when compared with open hip dislocation. Nonetheless, both procedures were found to have excellent patient-reported outcome measures and equivalent hip survival rates. ,
Labral debridement
Historically, arthroscopic treatment primarily consisted of labral debridement only. Byrd and Jones reported in 2009 on a cohort of 29 patients with osteoarthritis who underwent selective arthroscopic labral debridement and showed an increased Harris Hip Score (HHS) of 29 points (mean, 81 at 10-year follow-up). Of these patients, 88% with preoperative osteoarthritis progressed to a total hip arthroplasty (THA) at a mean of 63 months. However, there was limited correction of cam and/or pincer deformity in this cohort. Although labral debridement still remains a viable option for a select subset of patients, labral repair or labral reconstruction (LR) with correction of bony impingement is preferred for most symptomatic individuals. Preserving and/or restoring as much native, functional labrum as possible is paramount to maintaining proper mechanics to approximate a “normal” hip.
The first prospective study comparing labral debridement with repair in female patients was performed in 2013. The postoperative HOS activity of daily living (HOS-ADL) was shown to be significantly higher in those undergoing labral repair with minimum 1-year follow-up. In another study, midterm (3.5 year) follow-up showed similar benefits comparing labral repair with debridement with the repair cohort having significantly greater improvements in HHS and SF-12 at final follow-up. Limited long-term results comparing the procedures are available. Menge and colleagues reported at 10-year follow-up no demonstrated differences in modified HHS (mHHS; 90 vs 85), HOS-ADL (96 vs 96), or HOS-Sport (89 vs 87) when comparing labral repair with debridement. They did note a higher rate of conversion to THA in older patients, those with acetabular microfracture, and hips with preoperative joint space less than 2 mm. The risk of poor outcomes and high rate of conversion to THA in patients with osteoarthritis undergoing hip arthroscopic procedures has been well documented previously. , However, the degree to which degenerative changes of the hip should preclude a patient from arthroscopic surgery has not been completely elucidated because those with Tonnis grade 1 arthritic changes have been found to have similar favorable short-term outcomes compared with those with no arthritis (Tonnis grade 0) in a matched-controlled study.
With careful analysis of available literature, the authors favor primary acetabular labral repair over debridement whenever possible. Labral debridement could be considered in patients who are older, lower demand, with low radiographic or clinical risk of instability, or if the labrum is damaged beyond repair. Ideally the labral tear would be peripheral in nature without instability at its base and would have adequate functional size following debridement. However, this is a small subset of patients and if a labrum is irreparable, reconstruction should be strongly considered. Furthermore, the authors’ preference is to typically avoid hip arthroscopic management in patients who have greater than Tonnis grade 1 arthritic changes given the less favorable results and increased conversion to THA.
Labral repair
Over the past decade the treatment paradigm for management of acetabular labral tears with or without FAI has shifted in favor of labral preservation. Most symptomatic patients in the primary setting typically undergo arthroscopic labral repair ( Fig. 2 ). These patients are typically younger, active patients with an unstable labral base and adequate tissue quality to restore the labral suction seal following repair. Labral preservation is consistently associated with superior outcomes when compared with labral excision. An intact labrum not only restores the fluid suction seal but also increases articular surface contact area. This results in decreased articular friction, improved stability, and decreased contact pressure.
