Radiological evaluation of unstable (acute) slipped capital femoral epiphysis treated by pinning with Kirschner wires.

Treatment of slipped capital femoral epiphysis is still controversial with regard to the implants used for stabilization and the need for prophylactic treatment of the contralateral, unaffected, side. The objective of this study was to ascertain whether prophylactic transfixation of the epiphysis with Kirschner wires in patients with unstable slipped capital femoral epiphysis resulted in significant disturbance of the growth plate and impairment of further growth of the femoral neck and head. Between 1990 and 1999, 29 patients with unstable slipped capital femoral epiphysis were simultaneously treated with internal fixation of the epiphysis and metaphysis with 3-4 Kirschner wires on the affected and the not (yet) affected side. After a mean follow-up of 3.5 years, we evaluated the hip joints radiologically, analysing different roentgenological parameters (CCD angle, femoral head diameter, length of the femoral neck and sphericity of the femoral head). CCD angle, femoral head diameter and length of the femoral neck showed statistically significant (P<0.001, Student's t-test) differences between the affected and unaffected, but prophylactically pinned, sides. Asphericity of the femoral head was found in six cases only on the affected side, whereas all hips, which were operated prophylactically, showed spherical femoral heads at follow-up (P<0.02, Pearson's chi test). These results indicate that the slip itself may cause impairment of the femoral growth plate in patients with unstable slipped capital femoral epiphysis and not stabilization with Kirschner wires. Compared with other series from the literature using different implants (screws, nails), prophylactic transfixation of the epiphysis and metaphysis with Kirschner wires is less compromising to the growth plate on the not (yet) affected side.