Magnetic resonance imaging of skeletal muscle geometry and motion after surgery.

摘要

The goal of this dissertation was to evaluate the in vivo function of muscles in persons with cerebral palsy after surgical transfer of the rectus femoris. Rectus femoris transfer is frequently performed in persons with cerebral palsy who walk with a stiff-knee gait. Rectus femoris transfer is performed to convert the rectus femoris muscle from a knee extensor to a knee flexor thereby allowing the muscle to assist knee flexion during walking. However, outcomes of this procedure are variable, and it is not known if the surgery successfully converts the muscle to a knee flexor.; We hypothesized that scar tissue may form after surgery and adhere the rectus femoris to surrounding tissues in some patients. To test this hypothesis magnetic resonance imaging (MRI) was used to study the motion and geometry of the rectus femoris muscle in 10 control subjects (10 limbs) and 6 subjects (10 limbs) after rectus femoris transfer. The motion of the rectus femoris and vastus intermedius was measured during knee extension using cine phase contrast MRI. In the control subjects, the rectus femoris muscle consistently moved in the direction of the knee extensors and displaced more than the vastus intermedius. The rectus femoris also moved in the direction of the knee extensors in the tendon transfer subjects; however, the transferred rectus femoris displaced less than the vastus intermedius. These results suggest that the rectus femoris is not converted to a knee flexor, but its capacity for knee extension is diminished by the surgery.; Three-dimensional muscle paths reconstructed from MR images showed unexpected angulation in the rectus femoris muscle after transfer. Assessment of the images demonstrated that scar tissue was present in all subjects after rectus femoris transfer. Despite these findings, several subjects demonstrated improvements in knee flexion during walking. The measurements of muscle displacements, angular deviation of the rectus femoris muscle after transfer, and scar tissue visible on MR images suggest that scar tissue tethers the rectus femoris to the underlying vasti postoperatively. This dissertation demonstrates that MR imaging can be used to examine muscle motion and geometry in subjects with cerebral palsy after surgery.