Radiographic, histologic, and arthroscopic findings in amorphous calcifications of the hip labrum

The purpose of this study was to evaluate the clinical, radiographic, histologic, and intraoperative findings of an amorphous calcification involving the acetabular labrum.

From October 2008 to April 2013, all patients who underwent arthroscopic hip surgery for symptomatic intra-articular hip disorders and were found to have the characteristic calcific deposit involving the acetabular labrum were included. These patients were reviewed retrospectively on prospectively collected data. Radiographs were retrospectively evaluated for morphologic features of impingement and characteristics of labral calcification.

Sixteen patients were identified as having amorphous calcification at the time of arthroscopy. There were 15 women and 1 man. Mean age was 37.3 years (range, 30 to 50 years). Symptoms were present for a mean of 9.3 months (range, 3 to 48 months). All patients reported anterior groin pain. Fifteen (94%) patients had positive anterior impingement and 9 (56%) had positive results for lateral impingement. Calcifications measured on average 3.2 mm (range, 1.9 mm to 5.6 mm), and 14 had a clear separation from the rim with increased opacity compared with neighboring trabecular bone. Intraoperatively, the characteristic amorphous calcium deposit was located in the anterosuperior labrum, with the deposit found to be accessible from the capsule-labral recess in all cases. All patients had labral tears and all patients had at least one component of femoroacetabular impingement (FAI).

Calcification in the anterosuperior acetabular labrum presents with a consistent patient demographic and distinct radiographic and arthroscopic presentation that is different from os acetabuli. As with os acetabuli, one should have a high suspicion for FAI when this lesion is encountered.

Level IV, therapeutic case series.