Distal hamstring lengthening in ambulatory children with cerebral palsy: primary versus revision procedures

To document the benefits and limitations of distal hamstring lengthening (HL), 61 children (105 limbs) with cerebral palsy treated by distal HL with complete preoperative and postoperative evaluations were reviewed. There was significant improvement in popliteal angle, fixed knee flexion contracture, knee angle at foot contact (FC), and mid-stance knee extension after HL. On the other hand, the hip power generation peak decreased, and the anterior pelvic tilt increased. For the repeated HL (22 limbs), the fixed knee flexion contracture and knee flexion at FC improved. In a group of ten patients (17 limbs) with further postoperative follow up evaluations, the only significant clinical finding related to hamstring function between the first postoperative and the follow up evaluations with no intervening surgery was an increase in the popliteal angle of 20°. Because the popliteal angle may increase over time after HL with no other directly related gait changes, the indications for repeated HL should include fixed knee flexion contracture and increased knee flexion at FC. The increase in the popliteal angle alone should not be considered an indication for repeated HL.