Gait abnormalities following slipped capital femoral epiphysis treated with in situ fixation

Background: Slipped capital femoral epiphysis (SCFE) is a common disorder in adolescent for which no consensus exists regarding management. The aim of the present study was to analyze gait modifications following SCFE treated with in situ fixation (ISF) and to relate it to radiologic stage. Research question. To verify if gait biomechanics are impaired in patients with SCFE and to try to determine a degree of slippage from which gait modifications would appear. Methods: We evaluated 16 patients treated by ISF for SCFE with slippage ranging from 11 degrees to 61 degrees. Gait variables were compared to normal population according to age and walking speed and were normalized in Z-scores. Results: Spatiotemporal parameters, mechanical and energetic variables were inferior to vertical bar 1.5 vertical bar Z-scores and considered as normal. Kinematics showed increase of pelvic tilt and hip adduction. Kinetic variables showed modifications with increased hip extension moment. There was also a strong increase in power of hip extensor. Hip extension moment and power of hip extensors were significantly correlated to radiologic stage. Analysis of ROC curves showed a cut-off value of slippage about 25 degrees-30 degrees affecting kinematics of pelvis and hip and kinetic variables. Conclusion: The gait variables were close to normal values. Main modifications were observed in kinematic and kinetic data with a significant increase in extension moment and power generated at the operated hip. This could participate to long-term joint degradation observed in SCFE, even in mild slips. The clinical message is to control regularly SCFE with initial slippage greater than > 25-30 degrees to allow for early diagnosis of premature hip osteoarthritis.