The Journal of Pediatric Orthoepdics published a review of medical records to determine the rate of nerve palsy in children following hamstring lengthening surgery.   According to the review of the records, 9.6% of children had nerve palsy following the surgery.  Treatment for the nerve palsy was immediate knee flexion with 82.1% having relief of symptoms.

Reference:  Karol, Lori A. MD ; Chambers, Carol PT ; Popejoy, Debra MD ; Birch, John G. MD Nerve Palsy After Hamstring Lengthening in Patients With Cerebral Palsy.Journal of Pediatric Orthopaedics. 28(7):773-776, October/November 2008.