Background The causes of hip pain in osteoarthritis remain unknown. In recent years, Femoroacetabular impingement has attracted much attention as a cause of this symptom. In cases of knees, Roemer et. al. suggested that out of several osteoarthritic MRI features, synovitis is related to knee pain1.
Objectives To investigate the correlation between pain and synovitis in symptomatic hips, by using Contrast Enhanced Magnetic Resonance Images (CEMRI) and hip arthroscopy findings.
Methods Approval was obtained from Institutional Review Board.
Consent was obtained from 29 patients included in this study. In collecting the data, 10 exclusions were made on several grounds, including contraindication to the use of contrasts, high risk for anesthetics, and cases that had MR images taken with non-routine sequences.
Hip pain was evaluated with Hip Disability and Osteoarthritis Outcome Score (HOOS) and Japanese Orthopedic Association Hip Score (JOAHS).
Two board-approved orthopedic surgeons performed the hip arthroscopy, assessing the severity of synovitis on labral recess, acetabular fossa and lateral aspect of head-neck junction of femur.
Two board-approved musculoskeletal radiologists evaluated the thickness of synovial membrane of the hip at the specified location in Hip Osteoarthritis MRI Scoring System (HOAMS) and the designated location assessed under the arthroscopy, on CEMRI.
The correlation between clinical scores and severity of synovitis was evaluated.
Results 19 subjects were included (mean age 37.57 years old, range 11-66, BMI 23.89kg/m2 range 17.72-32.92kg/m2, 6 male and 13 female, 11 right hips 8 left hips).
The thickness of synovial membrane on CEMRI showed association with the synovial findings of hip arthroscopy (P=0.023).
Severity of synovitis showed association with clinical hip pain scores on the anterior aspects of the labral recess (P=0.009).
Conclusions The thickness of synovial membrane on CEMRI associated with the findings of hip arthroscopy. CEMRI is a reliable investigation for assessing the severity and location of synovitis responsible for hip pain.
Synovitis on the anterior aspect of the labral recess showed strongest association with hip pain. This is thought to be due to the large anterior range of movement of the hip.
Performing CEMRI may reveal the location of synovitis responsible for hip pain. This may reduce unnecessary investigative arthroscopy and shorten the length of procedure by locating the site of synovitis pre-operatively.
F.W. Roemer et.al. Osteoarthritis and cartilage. 2011; 19: 946-962
Disclosure of Interest None declared