Children with cerebral palsy often have problems standing up straight and walking normally. The increased muscle tone of the legs causes the knees to bend and move toward each other. The hips are then pulled into a position of internal (inward) rotation. Walking in a crouched position like this uses up energy and leads to a fixed deformity.
Researchers have tried to identify the abnormal activity patterns of muscles causing these changes. Orthopedic surgeons have tried many operations to help with this problem. The results of various studies are often in disagreement.
In this study, surgeons from Vanderbilt University and Shriner’s Hospital measured the effect of hamstring lengthening on hip rotation. The hamstrings muscle along the back of the thigh inserts around the knee. Contraction of the hamstring muscle bends the knee.
The goal was to increase knee extension by lengthening the hamstrings. The hope was that with more normal knee motion, the hip could move out of the internally rotated position that contributes to the crouched gait (walking) pattern.
Thirty-eight children with spastic diplegia cerebral palsy were included in the study. Spastic diplegia means that only the legs are affected by the condition. Before surgery, hip and knee range of motion (ROM) were measured. Full body gait analysis was also performed in a special motion analysis lab.
Surgery was done to release and lengthen the hamstring muscle. In some patients, other soft tissue procedures were also done at the same time. Everyone had rehab for six to 12 weeks afterwards. ROM and gait analysis were assessed again after surgery.
Although knee extension increased, hip rotation (internal and external) decreased when measured while lying still on a table. The authors reported that hamstring lengthening did decrease internal hip rotation when measured while walking. The surgery did help the children stand up out of the crouch position. Standing posture and gait pattern were not normal but improved.