| Since it was first proposed in 1987, rectus femoris (RF) transfer surgery has been used to treat gait abnormalities in children with spastic cerebral palsy (CP). The intention of this surgery is to hasten the onset and increase the magnitude of peak knee flexion angle in the swing phase of gait. Two questions about the biomechanical outcomes of this surgery are presented and tested using cadaver knee specimens in a purpose-built testing machine. Following experiments to deduce hip and ankle torques applied during stance, and to validate data recorded by the knee testing machine, two hypothesis-driven studies are described.;A consequence of transferring the RF is a reduction in knee extension force. This decrease in knee extension force may lead to an increase in crouch in the stance phase of gait. A study was conducted to determine if the amount of knee extension force lost when the RF is surgically transferred is of a sufficient magnitude to explain the increases in stance phase crouch observed in some patients following RF transfer surgery. A significant increase in knee extension force required to maintain stance following surgery was observed. However, the magnitude of that increase was not determined to be clinically significant. It was concluded that the loss of RF as an extensor of the knee is not likely the cause of observed changes in stance phase knee flexion.;Variations in surgical technique have led to differences in the line of action of the RF following its surgical transfer. A study was conducted to determine if a correlation between changes in the line of action of the RF and changes in postoperative knee biomechanics was present. Equivalence was shown in measurements of knee range of motion, and time required to reach peak knee flexion in swing when the RF was released at midfemur and near the distal end of the femur. It was concluded that the changes in biomechanics caused by RF transfer surgery should not be attributed to the line of action of the transferred RF, but rather to the effects of scar tissue formation between the RF and underlying muscle tissues. |
