Femoroacetabular impingement due to synovial chondromatosis of the hip joint

This article describes a rare case of primary synovial chondromatosis of the hip associated with classical femoroacetabular impingement. A 38-year-old man presented with left hip pain of 3 years' duration and range of motion (ROM) limitations. Flexion abduction external rotation and impingement tests were positive and preoperative Harris Hip Score was 68. Radiographs showed multiple loose bodies, a calcified labrum, and a bump at the head-neck junction. Computed tomography (CT) confirmed the findings. Acetabular overcoverage and the crossing over sign were present. The lateral center edge angle was 48° , acetabular roof angle was +2° , alpha angle was 80° , triangular index was 2 mm more than the radius of the femoral head, and anterior offset was 4.5 mm. Magnetic resonance imaging (MRI) revealed an acetabular labral tear, impaction on the femoral head-neck junction, and mild synovial hypertrophy with no acetabular cartilage damage. Loose body removal along with a total synovectomy, excision of the calcified labrum, and osteochondroplasty of the head-neck junction were performed after safe surgical dislocation. At 6-month follow-up, the patient was doing well with a Harris Hip Score of 96, improved ROM, and negative flexion abduction external rotation and impingement tests. Early diagnosis of synovial chondromatosis and impingement can be made by MRI and CT. Clinically, flexion abduction external rotation and impingement tests are positive in 99% and 97% of cases, respectively. Although arthroscopy management has been described for both the entities separately, it has drawbacks. With an open procedure, debridement of the hip joint and excision of femoral and acetabular impingement deformities are possible at the same time.