Femoroacetabular Impingement Research Symposium

Osteoarthritis (OA) of the knee and hip is both common and costly. Because of the aging US population, the number of persons burdened by arthritis or chronic joint disability is expected to exceed 40 million by 2030.1 Over the next two decades, the number of total hip arthroplasties performed in the United States is expected to increase by 174% to nearly 572,000 cases per year.2 Accounting for direct medical care only, the cost associated with the treatment of joint dysfunction would reach nearly $100 billion per year in the United States alone.3,4 It is clear that advances in the costefficient and efficacious management of OA would be of benefit to society. Femoroacetabular impingement (FAI) in young adults is a highly prevalent hip deformity that can lead to the development of OA of the hip. Up to 25% of the young adult male population may have this deformity,5 and increasing epidemiologic data support the importance of this deformity in the development of hip OA.6,7 Recent advances in open and arthroscopic techniques to correct FAI hold the promise of not only relieving symptoms but also potentially altering the course of OA progression. Increasing evidence suggests that these surgical procedures can be effective in relieving symptoms; however, most of the evidence comes from uncontrolled retrospective studies.8 Additionally, it is becoming clear that FAI deformity can be variable and complex, often resulting in more variability in surgical treatment options. At present, much treatment variation exists, suggesting the need for standardization of the assessment and treatment options for the deformity. Furthermore, very limited investigation has been performed regarding the efficacy of nonsurgical treatment protocols. To resolve the issues surrounding FAI treatment, well-conducted comparative studies will be required. Toward this end, we organized the 2012 American Academy of Orthopaedic Surgeons/Orthopaedic Research Society Femoroacetabular Impingement Research Symposium, held May 9–11, 2012, in Chicago, IL, with an emphasis on a multidisciplinary approach and focused on summarizing current knowledge, developing consensus, and identifying research strategies for several key issues related to FAI. Among the topics discussed were disease definitions, radiographic and clinical assessment methods, treatment strategies, clinical outcome methods, and possible clinical trial designs to study the treatment efficacy for FAI. The following conclusions represent some of the consensus reached during this symposium. FAI is a clinical entity in which a pathologic mechanical process causes hip pain when morphologic abnormalities of the acetabulum and/or femur combined with vigorous hip motion, especially at the extremes, lead to repetitive collisions that damage the softtissue structures within the joint. Often, femoral or acetabular structural abnormalities may predispose a hip to FAI. In rare instances and even in a structurally normal hip, however, excessive motion and activity may lead to damage. Because of the diverse nature of this condition, it has been difficult to define it precisely for epidemiologic and clinical studies. For an operational definition in clinical trials looking at treatment efficacy, however, a consensus was reached that the subjects need to be symptomatic, have clinical presentation consistent with FAI, and have radiologic hip deformity characteristics consistent with FAI. Furthermore, sufficient epidemiologic data exist at present to support the conclusion that certain FAI morphology, such as cam deformity, is common in young adult hips and may predispose to the later development of OA in certain patients. In most hips, however, the presence of a cam lesion is not sufficient in isolation to lead to the development of OA. Furthermore, insufficient evidence exists to confirm a similar association between the presence of a pincer deformity and the development of OA. Additional data from longitudinal population studies are needed to determine which persons with FAI-related morphologic abnormalities have the greatest risk of developing OA at a relatively young age. It is becoming clear that, although the overall joint morphology is important, joint kinematics, the cellular mechanobiology of cartilage, and the biologic response to cartilage injury may be equally important factors in the development of OA in these hips. In addition to population-based epidemiologic studies, a more mechanistic understanding of the interplay between abnormal hip joint mechanics and cartilage degradation would help identify the specific biomechanical and biologic factors that would destine a hip with FAI morphology to early end-stage OA. A clearer understanding of these factors could be the foundation of new treatments that could halt, and potentially even reverse, the joint injury created by FAI morphology. The management of FAI for the majority of cases has transitioned from open surgical techniques using the dislocation approach to arthroscopic and less invasive open techniques. The advantages of less invasive approaches to the correction of FAI definitely are appealing. However, achieving effective bone correction and determining the type and amount of bony correction that is necessary to solve the problem remain challenging. At present, much effort is spent refining the arthroscopic techniques necessary for FAI correction, whereas minimal investigation has been done into the role of nonsurgical treatment modalities. Larger comparative clinical trials are needed to address the current limitations and provide scientific guidance for evidence-based clinical practice. Toward this goal, a standardized radiographic and clinical outcome assessment is needed. The primary goal of a clinical trial in FAI will be to assess symptom modification. Ultimately, however, the question of whether the progression of OA is being altered will need to be answered. Advanced imaging technologies such as delayed gadolinium-enhanced MRI of cartilage and T1rho (ie, T1 in the rotating frame) may provide the tools to observe early alterations in cartilage biochemistry, which may be an early biomarker of cartilage preservation. Advances in the development of biochemical biomarkers may provide the necessary tools to evaluate disease modification, as well. Currently, an urgent need exists for a randomized clinical trial that could compare the surgical and nonsurgical management of symptomatic FAI to justify definitively the need for surgical intervention in these patients. Current arthroscopic treatment methods are reasonably refined. Surgeon equipoise and doubt among payers regarding the efficacy of surgical treatment still remain, however. If the efficacy of surgical treatment can be demonstrated via a well-conducted prospective clinical trial, then comparative prospective cohort trials or randomized controlled trials comparing different elements of the surgical technique should be performed to refine the treatment algorithm. It is our sincere hope that this consensus conference is a first step toward a continual improvement in the management of hip impingement disorders and secondary hip OA. Acknowledgments The American Academy of Orthopaedic Surgeons (AAOS) acknowledges the following contributors to the 2012 American Academy of Orthopaedic Surgeons/Orthopaedic Research Society Femoroacetabular Impingement Research Symposium: Peter C. Amadio, MD, Nigel Arden, MBBS, FRCP, MSc, MD, Mathias Bostrom, MD, J. W. Thomas Byrd, MD, John Callaghan, MD, John C. Clohisy, MD, David T. Felson, MD, MPH, Kharma C. Foucher, MD, PhD, Siôn Glyn-Jones, MA, MBBS, DPhil, FRCS (Orth), Alan J. Grodzinsky, ScD, Marcie H. Harris-Hayes, MD, Young-Jo Kim, MD, PhD, Steven Kymes, PhD, Mario Lamontagne, PhD, Cara Beth Lee, MD, Michael Leunig, MD, Cara L. Lewis, MD, Stefan Lohmander, MD, PhD, Bent Lund, MD, Jon Lurie, MD, MS, T. Charles Mamisch, MD, Travis Matheney, MD, MLA, Christine M. McDonough, MS, PhD, PT, Michael B. Millis, MD, Amanda E. Nelson, MD, MSCR, Jeffrey J. Nepple, MD, Michael Nevitt, PhD, Shane J. Nho, MD, Steve Olson, MD, FACS, Joan Overhauser, PhD, Jim S. Panagis, MD, MPH, Javad (Jay) Parvizi, MD, Christopher Peters, MD, David Podeszwa, MD, Heidi Prather, DO, Kawan S. Rakhra, MD, Ewa M. Roos, PhD, Linda J. Sandell, PhD, Wudbhav N. Sankar, MD, Carla R. Scanzello, MD, PhD, Ken Schechtman, PhD, Perry Schoenecker, MD, Klaus A. Siebenrock, MD, Andrew Speirs, PhD (Candidate), Kurt Spindler, MD, Robert Trousdale, MD, Linda VanDillen, PT, PhD, Peter Wall, MBChB (Honours), MRCS (Edin), Rick Wright, MD, and Yi-Meng Yen, PhD. The AAOS and the Orthopaedic Research Society recognize the organizations and companies whose support made this symposium possible: The National Institute of Arthritis and Musculoskeletal and Skin Diseases/National Institutes of Health (NIAMS/NIH) Smith & Nephew (Silver Level) Biomet (Bronze Level) Additional support for the 2012 AAOS/Orthopaedic Research Society Femoroacetabular Impingement Research Symposium was provided by Zimmer. Support for the FAI supplement publication is provided by OREF, thanks to the generosity of an anonymous donor.