Remodelling of femoral head-neck junction in slipped capital femoral epiphysis: a multicentre study.

PURPOSE: We examined the remodelling of the femoral head-neck junction in patients with slipped capital femoral epiphysis (SCFE) and the frequency of residual cam deformities.

METHODS

We reviewed 69 hips in 56 patients with stable SCFE who had undergone in situ pinning. Mean age at slip was 11.7 years and the follow-up period 63.4 months. Cam deformity was evaluated using the anterior offset alpha (α) angle and head-neck offset ratio (HNOR).

RESULTS

The average α angle and HNOR significantly improved from 76.2° to 51.3° and 0.086 to 0.135, respectively; 25 hips (36.2%) still had an α angle greater than 50°, and 32 hips (46.4%) had an HNOR of under 0.145. A multivariate analysis selected age at onset and slip angle as risk factors for cam deformity, with cutoff values 11.1 years and 21.0°, respectively.

CONCLUSIONS

Although most hips had remodelling of the head-neck junction, 29.4 % had residual cam deformities that may be susceptible to femoroacetabular impingement.