Labral Ossification and Sacroiliac Joint Disease: Could There Be a Link to an Autoimmune Etiology?

PURPOSE: To determine the prevalence of ipsilateral sacroiliac (SI) joint disease among patients with symptomatic femoroacetabular impingement (FAI) associated with labral ossification (LO) who underwent hip arthroscopy compared with a matched control group of patients with symptomatic FAI and no LO.

METHODS

Computed tomography (CT) scans of all patients undergoing arthroscopic correction of FAI were obtained. The inclusion criterion for the study group was a diagnosis of FAI with a secondary diagnosis of LO made by plain radiography, CT, or magnetic resonance imaging or made intraoperatively. The exclusion criterion was the absence of evidence of LO. We reviewed 52 patients (56 hips) with LO to assess the SI joint and compared them with a control group matched by age, sex, and FAI type. The SI joints were graded according to the modified New York criteria.

RESULTS

CT scans were available for evaluation of the ipsilateral SI joint in 28 patients (29 hips) with LO: 17 women and 11 men with an average age of 44.6 years (range, 26-56 years). Of the hips, 23 had combined FAI and 6 had pincer-type FAI. The control group consisted of 29 hips, exactly matched for sex and FAI type, with an average age of 44.8 years (range, 21-58 years). Grade 3 SI joint abnormalities were significantly more prevalent in the LO group (28%) than in the control group (7%, P = .037), and grade 0 or 1 changes (relatively normal SI joints) were significantly less common in patients with LO (38%) than in controls (72%, P = .008). Subanalysis showed that 35% of the LO group aged 45 years or younger had ipsilateral grade 3 SI joint abnormalities compared with none of the control patients aged 45 years or younger (P = .041). Grade 3 changes were found in 42% of male patients with LO compared with 8% of male controls (P = .155). Grade 3 changes were noted in 18% of women in the LO group compared with 6% of female controls (P = .601).

CONCLUSIONS

Patients with symptomatic FAI and LO are more likely to show associated SI joint pathology than patients with FAI not involving LO. These differences are greatest among men and among patients aged 45 years or younger.

LEVEL OF EVIDENCE: Level III, retrospective case-control study.