Multicenter Outcomes After Hip Arthroscopy: Epidemiology (MASH Study Group). What Are We Seeing in the Office, and Who Are We Choosing to Treat?
Authors’ Disclosure Statement: Dr. Nho reports that he is Deputy Editor-in-Chief of The American Journal of Orthopedics; receives research support from Allosource, Arthrex, Athletico, DJ Orthopaedics, Linvatec, Miomed, Smith & Nephew, and Stryker; is a paid consultant to Ossur and Stryker; and receives publishing royalties and financial or material support from Springer. Dr. Christoforetti reports that he receives support from Arthrex and Breg. Dr. Ellis reports that he receives intellectual property royalties from Medacta and research support from Smith & Nephew and is a paid consultant to Stryker. Dr. Matsuda reports
that he receives intellectual property royalties from Arthrocare, Zimmer Biomet, and Smith & Nephew and is a paid consultant to Orthopedics Overseas and Zimmer Biomet. Dr. Salvo reports that he is a paid consultant to Stryker. Dr. Wolff reports that he is a consultant to Stryker. Dr. Van Thiel reports that he is a paid consultant to Smith & Nephew and Zimmer Biomet, receives royalties from Zimmer Biomet, and has equity ownership in Zimmer Biomet. Dr. Stubbs
reports that he is a consultant to Smith & Nephew; receives research support from Bauerfeind and departmental or divisional support from Arthrex, Mitek, and Smith & Nephew; and owns stock in Johnson & Johnson. Dr. Carreira reports that he is a paid consultant to Zimmer Biomet. Dr. Kivlan reports no actual or potential conflict of interest in relation to this article.
As the field of hip arthroscopy continues to grow rapidly, our understanding of the population of patients undergoing hip arthroscopy has led to improved diagnosis and management of hip joint pathologies. The Multicenter Arthroscopic Study of the Hip (MASH) Study Group conducts multicenter clinical studies in arthroscopic hip preservation surgery. Patients undergoing arthroscopic hip preservation surgery are enrolled in a large prospective longitudinal cohort at 10 separate sites nationwide by 10 fellowship-trained hip arthroscopists. In this study, we collected epidemiologic data on the 1738 patients who enrolled between January 2014 and November 2016. These data include demographics, pathologic entities treated, patient-reported measures of disease, and surgical treatment preferences. Our study results showed that patients who elected hip arthroscopy were younger to middle-aged white females with pain primarily located in the groin region. Most had pain for at least 1 year, and it was commonly exacerbated by sitting and athletic activities. Patients reported clinically significant pain and functional limitation and a decrease in physical and mental health. It was not uncommon for patients to have undergone another, related surgery and nonoperative treatments, including intra-articular injection and/or physical therapy, before surgery. There was a high incidence of abnormal hip morphology suggestive of a cam lesion, but the incidence of arthritic changes on radiographs was relatively low. Labral tear was the most common diagnosis, and most often it was addressed with repair. Many patients underwent femoroplasty, acetabuloplasty, and chondroplasty in addition to labral repair.
- MASH is a multicenter arthroscopic study of the hip that features a large prospective database of 10 separate institutions in the United States.
- The mean patient demographic was age 34.6 years, BMI 25.9 kg/m2, 62.8% females, and 97% white.
- Most patients had anterior or groin pain, but 17.6% had lateral hip pain, 13.8% had posterior hip pain, and 2.9% had low back or sacral pain.
- Patients typically had pain for about 1 year that was worsened with athletic activity as well as sitting.
- The most common surgical procedures that were performed included labral surgery in 64.7%, femoroplasty in 49.9%, acetabuloplasty in 33.3%, and chondroplasty in 31.1%
Arthroscopic surgery of the hip has been growing over the past decade, with drastically increasing rates of arthroscopic hip procedures and increased education and interest in orthopedic trainees.1-3 The rise of this minimally invasive surgical technique may be attributed to expanding knowledge of surgical management of morphologic hip disorders as a means of hip preservation. Many arthroscopic techniques have been developed to treat intra-articular hip joint pathologies, including femoroacetabular impingement (FAI), labral tears, and cartilage damage.4-11 These hip pathologies are widely recognized as painful limitations to activities of daily living and sports as well as early indicators of hip osteoarthritis.12,13 Limited evidence suggests that arthroscopic treatment of these intra-articular hip joint pathologies preserves the hip from osteoarthritis and progression to total hip arthroplasty.13-15
FAI is the most common etiology of pathologies related to arthroscopic surgery of the hip, including both labral tears and cartilage damage.4,7,14 FAI is a morphologic bone disorder characterized by impingement of the femur and the acetabulum on flexion or rotation. The etiology of FAI is not completely understood, but evidence suggests that stress to the proximal femoral physis during skeletal growth increases the risk of developing femoral head and neck deformations leading to cam-type FAI.15-17 Understanding the characteristics of the patient population in which FAI occurs may shed light on the processes of intra-articular damage, such as labral tears and cartilage damage.
In the present study, we collected epidemiologic data, including demographics, pathologic entities treated, patient-reported measures of disease, and surgical treatment preferences, on a hip pathology population that elected to undergo arthroscopic surgery. These data are important in gaining a better understanding of the population and environment in which hip arthroscopy is performed across multiple centers throughout the United States and may help guide clinical practice and research to advance hip arthroscopy.
The Multicenter Arthroscopic Study of the Hip (MASH) Study Group conducts multicenter clinical studies in arthroscopic hip preservation surgery. Patients are enrolled in this large prospective longitudinal study at 10 sites nationwide by 10 fellowship-trained hip arthroscopists. Institutional Review Board approval was obtained from all institutions before patient enrollment. After enrollment, we collected comprehensive patient data, including demographics, common symptoms and their duration, provocative activities, patient-reported outcome measures (modified Harris Hip Score, International Hip Outcome Tool, 12-item Short Form Health Survey, visual analog scale pain rating, Hip Outcome Score), physical examination findings, imaging findings, diagnoses, surgical findings, and surgical procedures.
All study participants were patients undergoing arthroscopic hip surgery by one of the members of the MASH Study Group. Patients with incomplete preoperative information (needed for data analysis) were excluded. Data analysis was performed with SPSS Statistics Version 21.0 (SPSS Inc.) to obtain descriptive statistics of the quantitative data and frequencies of the nominal data.
Between January 2014 and November 2016, we enrolled 1738 patients (647 male, 1091 female) in the study. Table 1 lists the demographics of the population.
Regarding symptom location, 40.9% of patients described pain in the groin region, 24.2% in the anterior hip region, and 11.3% in a C-sign distribution (Table 2).
Table 3 lists the results of the patient-reported outcome measures.
Of the 1738 patients enrolled, 424 (24.4%) had prior surgery related to current symptoms, 252 (14.5%) had 1 previous surgery, 120 (6.9%) had 2 previous surgeries, and 52 (3%) had 3 previous surgeries. Twenty-six patients (1.5%) had a previous revision hip arthroscopy on the ipsilateral side, and 14 (0.8%) had a previous hip arthroscopy on the contralateral side. Before surgery, 80% of patients received an intra-articular injection of corticosteroid and lidocaine. The peritrochanteric region was injected in 11.5% of patients and the psoas bursa in 2.2% (Table 4).
Of the 1011 patients who had magnetic resonance imaging (MRI) performed, 943 (93.3%) had abnormal acetabular labrum findings, and 163 (17.1%) had acetabular articular damage. According to radiographic evaluation, 953 patients had abnormal hip joint morphology consistent with FAI. Figure 3 shows the FAI classification percentages.
On clinical examination, 1079 patients (62.1%) had a positive anterior impingement sign. The subspine impingement sign was positive in 447 patients (25.7%), and the trochanteric pain sign was positive in 400 (23%). Table 5 lists range-of-motion values for flexion and hip rotation from 90° of flexion.
As seen in Table 6, labral pathology was the most common diagnosis (1426/1738 patients, 82%).
As seen in Table 7, the most common procedure was femoroplasty (867/1738, 49.9%).
In this study, we collected epidemiologic data (demographics, pathologic entities treated, patient-reported measures of disease, surgical treatment preferences) from a large multicenter population of hip pathology patients who elected to undergo arthroscopic surgery. Our results showed these patients were most commonly younger to middle-aged white females with pain primarily in the groin region. Most had pain for at least 1 year, and it was commonly exacerbated by sitting and athletics. Patients reported clinically significant pain and functional limitation, which showed evidence of affecting general physical and mental health. It was not uncommon for patients to have undergone another, related surgery and nonoperative treatments, including intra-articular injection and/or physical therapy, before surgery. There was a high incidence of abnormal hip morphology suggestive of a cam lesion, but the incidence of arthritic changes on radiographs was relatively low. Labral tear was the most common diagnosis, and most often it was addressed with repair. Many patients underwent femoroplasty, acetabuloplasty, and chondroplasty in addition to labral repair.
According to patient-reported outcome measures administered before surgery, 40% to 65% of patients seeking hip preservation surgery reported functional deficits and pain—which falls within the range of results from other multicenter studies on the epidemiology of FAI.18,19 There was, however, a high amount of variability in individual scores on the functional and pain measures; some patients rated their functional ability very high. These findings were supported by the general health forms measuring global physical and mental health. Mean Physical Health and Mental Health scores on the 12-item Short Form Health Survey indicated that patients seeking hip preservation surgery thought their hip condition affected their general well-being. This finding is consistent with research on FAI,18 hip arthritis,20 and total hip arthroplasty.19Our results further showed that hip arthroscopists commonly prescribed alternative treatment measures ahead of surgery. Before elective surgery, 80% of patients received an intra-articular injection, underwent physical therapy, or both. This could suggest a high failure rate for patients who chose conservative treatment approaches for hip-related pathology. However, our study was limited in that it may have included patients who had improved significantly with conservative measures and decided to forgo arthroscopic hip surgery. Although conservative treatment often is recommended in an effort to potentially avoid surgery, there is a lack of research evaluating the efficacy of nonoperative care.21,22Analysis of diagnostic imaging and clinical examination findings revealed some unique characteristics of patients undergoing elective hip preservation surgery. MRI showed labral pathology in an overwhelming majority of these patients, but few had evidence of articular damage. Previous research has found a 67% rate of arthritic changes on diagnostic imaging, but our rate was much lower (17%).23 Radiograph evaluation confirmed the pattern: More than 90% of our patients had Tönnis grade 0 osteoarthritis. Tönnis grade 1 or 2 osteoarthritis is a predictor of acetabular cartilage degeneration,23 and long-term studies have related these osteoarthritic changes to poorer hip arthroscopy outcomes.24 Thus, the lower incidence of osteoarthritis in our study population may reflect current evidence-based practice and a contemporary approach to patient selection.
Most of our patients had isolated cam-type FAI as opposed to pincer-type FAI or a combination of cam and pincer—contrary to research findings that combination cam–pincer FAI is most prevalent.25,26 Our results are more consistent with more recent research findings of a higher incidence of isolated cam lesion, particularly in female patients, and combination cam–pincer in male patients.18,27,28 Similar distributions of surgical procedures and diagnoses exist between the present study and other multicenter evaluations of the epidemiologic characteristics of patients with hip pathology.18Our study had several limitations. First, the population consisted entirely of patients who sought evaluation by a hip arthroscopy specialist and underwent elective surgery. Therefore, the data cannot be applied to a more general orthopedic population or to patients who consult other medical specialists. Second, the population, which was 97% white and had small percentages of African-American, Latino, and Asian patients, lacked ethnic diversity. This finding is consistent with recent epidemiologic research in which ethnicity was identified as a factor in patterns of hip disease.13,29,30 Access to specialists, however, was likely affected by multiple other factors. Fourth, the validity and the reliability of the imaging modalities used have been questioned.31-33 There is controversy regarding ideal imaging modalities for assessment of articular cartilage damage31,32 and FAI. However, the modalities that we used to determine diagnoses in this study are well supported26 and represent common practice patterns.
Am J Orthop. 2017;46(1):35-41. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.