In this study, researchers at the Cleveland Clinic Foundation (Ohio) report on which reconstructive osteotomy restores normal muscle length in patients with slipped capital femoral epiphysis (SCFE). They also try to answer the question of how muscle length differs in hips with mild versus severe SCFE deformity.
Slipped capital femoral epiphysis (SCFE) is a condition that affects the hip in teenagers between the ages of 12 and 16. In this condition, the growth center of the hip (the capital femoral epiphysis) slips backwards on the top of the femur (the thighbone). If untreated, this can lead to serious problems in the hip joint later in life.
Surgery is usually done right away. A single long screw is used to stop the epiphysis from slipping further. If this doesn’t work, then another operation may be needed to restore normal hip alignment and keep the situation from getting worse. In such cases, the most commonly performed operation is the reconstructive or wedge osteotomy.
One of the drawbacks of this operation is a compensatory deformity that alters hip function. The position of the hip abductor muscles changes resulting in decreased hip strength and motion. By using a life-sized synthetic model of the pelvis and hip, two methods of wedge osteotomy were evaluated.
The length of the abductor muscle was measured after subtrochanteric and femoral neck base osteotomies. All of the changes in muscle position and length were observed when the hip was bent or flexed. The model explains this by seeing how much hip rotation is needed to bend the hip when there is a severe SCFE deformity.
The results of this study confirmed that the osteotomy done at the femoral neck base was better able to align the hip in a normal position. Osteotomies done higher on the femur can cause greater deformity. A detailed description of the anatomy and changes in muscle length was provided for each procedure.
The authors admit their use of a plastic model may not mimic normal human anatomy exactly. Muscles and tendons tend to adapt over time in response to bony deformity. Such changes were not figured into the mechanical model in this study. Further study of this problem is needed.