[Growth and deformity after in situ fixation of slipped capital femoral epiphysis].

BACKGROUND

For mild to moderate slipped capital femoral epiphysis (SCFE) in situ fixation is the current treatment standard. However, concerning the implant selection (screw versus k-wires) as well as the prophylactic stabilisation of the non-affected hip, controversies still exist. The aim of this study was to analyse femoral residual growth and femoral deformities after in situ fixation of SCFE either with k-wires or screws.

PATIENTS AND METHODS

We conducted a retrospective analysis of the radiographs of adolescents treated for SCFE in our department between 01/2003 and 02/2011. To evaluate femoral growth the articulo-trochanteric distance, centro-trochanteric distance, caput-collum-diaphyseal angle, pin-joint ratio and pin-physis ratio were determined. The femoral deformity was assessed by measuring the sphericity of the femoral head. Degenerative changes were evaluated in the final radiographs. Statistical analysis was performed concerning differences between therapeutically and prophylactically treated hips as well as stabilisations with k-wires and screws.

RESULTS

A total of 22 patients (female : male = 14 : 8, mean age girls: 11 ± 1 years, boys: 13 ± 2 years) with 26 slipped capital femoral epiphyses was analysed. K-wires were used for fixation in 4 hips each therapeutically and prophylactically, 22 hips with SCFE and 14 non-affected hips were stabilised with screws. Treatment with screws did not lead to significantly earlier physeal closure than k-wire pinning. Regarding the femoral growth parameters a significant decrease in the articulo-trochanteric distance and CCD angle was detectable in all groups. The pin-joint ratio revealed an adequate residual growth in 58 % of the therapeutically and in 72 % of the prophylactically treated hips without significant difference between k-wires and screws. The pin-physis ratio demonstrated similar values. Regarding the femoral deformity the SCFE hips resulted in a significantly reduced sphericity, which remained unchanged during follow-up. The prophylactic stabilisation did not result in any deterioration of sphericity.

CONCLUSION

The results of this study imply that further growth of the proximal femur after insertion of a sliding screw for in situ stabilisation of mild to moderate slipped capital femoral epiphysis does occur. Furthermore, an increase of deformity during follow-up through screw fixation as compared to pinning was not noticed. Hence, the assumption that screw fixation leads to permanent physeal impairment cannot be confirmed. The consideration of these results may be helpful for implant selection as well as indicating prophylactic surgery for non-affected hips.