Knee Flexion Deformity in Cerebral Palsy

Abstract

In children with cerebral palsy (CP), the most common problem at the knee is a flexion deformity or an alternative definition is limited knee extension. By far the most common problem occurring in the knee is contracture of the hamstring muscles, which, if left untreated in some patients, leads to fixed knee flexion contracture. For individuals who are ambulatory, Gross Motor Function Classification System (GMFCS) I–III, limited ability for full knee extension can lead to significant disability with a flexed knee gait posture called crouch gait. The increased knee flexion may increase the energy cost of walking and lead to high stress in the extensor mechanism. The etiology of this increased knee flexion or crouch gait posture is multifactorial and not entirely due to problems at the knee. Children with more limited motor ability at the GMFCS level IV–V also developed increased knee flexion contractures because of being in a seated position for most of their day. Additionally, many of these children like to sleep with their hips and knees flexed, further aggravating the flexion deformity. As the contractures and knee flexion deformity become severe in children who are constantly sitting, they develop posterior pelvic tilt, loss of lumbar lordosis, and increased kyphotic sitting posture. Children at GMFCS level IV–V also should be spending time weight-bearing in standers with knees and hips extend it. Progressive flexion deformities at the knees preclude comfortable standing or functional weight-bearing. The goal of this chapter is to address the problems caused by lack of knee extension, present treatment options, and expected outcomes.