Zhou, Jun

Background: Femoroacetabular impingement (FAI) is a common cause of hip pain and a known risk factor for hip osteoarthritis (OA) and total hip arthroplasty (THA) at a young age. Unfortunately, little is known about the specific factors associated with an increased risk of OA. Purpose: To (1) report the overall rate of symptomatic hip OA and/or THA in patients with FAI without surgical intervention and (2) identify radiographic features and patient characteristics associated with hip OA. Study Design: Case-control study; Level of evidence, 3. Methods: A geographic database was used to identify all patients with hip pain and radiographs between 2000 and 2016. Chart review was performed to identify patients with FAI. Patient medical records were reviewed to obtain demographic information, clinical history, physical examination findings, imaging details, and treatment details. Kaplan-Meier analysis was used to determine the rate of hip OA. Univariate and multivariate proportional hazard regression models were performed to determine risk factors for OA. Results: The study included 952 patients (649 female; 303 male; 1104 total hips) with FAI. The majority of hips had mixed type (n = 785; 71.1%), 211 (19.1%) had pincer type, and 108 (9.8%) had cam type. Mean age at time of presentation was 27.6 ± 8.7 years. Mean follow-up time was 24.7 ± 12.5 years. The rate of OA was 13.5%. THA was performed in 4% of patients. Male sex, body mass index (BMI) greater than 29, and increased age were risk factors for OA (male sex: hazard ratio [HR], 2.28; P < .01; BMI >29: HR, 2.11; P < .01; per year of increased age: HR, 1.11; P < .01.). Smoking and diabetes mellitus were not significant risk factors. No radiographic morphological features were found to be significant risk factors for OA. Conclusion: At mean follow-up of 24.7 years, 14% of hips had symptomatic OA and 4% underwent THA. BMI greater than 29, male sex, and increased age at the time of presentation with hip pain were risk factors for hip OA. The cohort consisted of a large percentage of mixed-type FAI morphologies, and no specific radiographic risk factors for OA were identified.

Background: Radiography is the initial imaging modality used to evaluate femoroacetabular impingement (FAI), and diagnostic radiographic findings are well-established. However, the prevalence of these radiographic findings in patients with hip pain is unknown. Purpose: The purpose was 3-fold: (1) to determine the overall prevalence of radiographic FAI deformities in young patients presenting with hip pain, (2) to identify the most common radiographic findings in patients with cam-type FAI, and (3) to identify the most common radiographic findings in patients with pincer-type FAI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A geographic database was used to identify patients aged 14 to 50 years with hip pain between the years 2000 to 2016. The following were evaluated on radiographs: cam type: typical pistol grip deformity, alpha angle >55°; pincer type: crossover sign (COS), coxa profunda or protrusio acetabuli, lateral center edge angle (LCEA) ≥40°, Tönnis angle <0°; and mixed type: both cam- and pincer-type features. Posterior wall sign (PWS) and ischial spine sign (ISS) were also evaluated. The prevalence of each was determined. Descriptive statistics were performed on all radiographic variables. Results: There were 1893 patients evaluated, and 1145 patients (60.5%; 1371 hips; 374 male and 771 female; mean age, 28.8 ± 8.4 years) had radiographic findings consistent with FAI. Of these hips, 139 (10.1%) had cam type, 245 (17.9%) had pincer type, and 987 (72.0%) had mixed type. The prevalence of a pistol grip deformity and an alpha angle >55° was 577 (42.1%) and 1069 (78.0%), respectively. The mean alpha angle was 66.9°± 10.5°. The prevalence of pincer-type radiographic findings was the following: COS, 1062 (77.5%); coxa profunda, 844 (61.6%); ISS, 765 (55.8%); PWS, 764 (55.7%); Tönnis angle <0°, 312 (22.8%); LCEA ≥40°, 170 (12.4%); and protrusio acetabuli, 7 (0.5%). Conclusion: The overall prevalence of radiographic findings consistent with FAI in young patients with hip pain was 60.5%. Radiographic findings for mixed-type FAI were the most prevalent. The most common radiographic finding for cam-type FAI was an alpha angle >55°. The most common radiographic finding for pincer-type FAI was the COS.