Motor branch of the rectus femoris: Anatomic location for selective motor branch block in stiff-legged gait

Objective: To determine the ideal target point for selective motor branch block of the rectus femoris to treat stiff-legged gait. Design: Descriptive study. Setting: Anatomic institute of a university school of medicine in Korea. Cadavers: Twenty-two preserved adult cadavers. Intervention: The anterior thigh of the cadaver was dissected below the inguinal ligament. The motor branches of the 4 heads of the quadriceps were identified and traced from just below the inguinal ligament to the motor points. Main Outcome Measures: The point T, where the motor branch of the rectus femoris is divided into smaller subbranches, was identified. Its location in relation to the surface anatomic landmarks was determined on the basis of the 2 anatomic lines that connect the anterior superior iliac spine to the medial femoral condyle, and the issuing spot of the femoral nerve below the inguinal ligament to the middle of the superior pole of the patellar. Results: The motor branch of the rectus femoris was divided into 2 subbranches at point T just before it reached the muscle. It nearly touched the medial margin of the rectus femoris at a proximal one-fourth to one-fifth point on 2 anatomic lines. The superior subbranch penetrated the muscle fascia at the posterior surface of the proximal one third of the muscle, whereas the inferior subbranch penetrated the muscle fascia at the medial border of the muscle. Conclusion: The point T is the most suitable target point to selectively block the motor branch of the rectus femoris without affecting the other 3 motor branches of the femoral nerve in the treatment of stiff-legged gait.