Does patella lowering improve crouch gait in cerebral palsy? Comparative retrospective study.

BACKGROUND

Patella lowering aims to improve quadriceps function as a means of correcting crouch gait in patients with cerebral palsy. Few studies have assessed the effects of patella lowering as a component of multilevel surgery.

HYPOTHESIS

Including patella lowering into the components of multilevel surgery is beneficial in patients with crouch gait and patella alta.

MATERIAL AND METHODS

In 12 lower limbs with patella alta (Caton-Deschamps index>1.4) in 41 children with cerebral palsy, patella lowering was performed, without distal femoral extension osteotomy or hamstring release. Among limbs with similar surgical procedures (e.g., hamstring lengthening, rectus femoris transfer) except for patella lowering, controls were selected retrospectively by matching on a propensity score for patella lowering. The propensity score was computed based on preoperative knee flexion contracture, knee extension lag, and minimum knee flexion at mid-stance. Clinical and 3D kinematic data were compared between the two groups.

RESULTS

The improvement in minimum knee flexion at mid-stance was significantly greater in the group with patellar lowering (-24°±12°vs. -12°±7°). The Gait Deviation Index improved similarly in the two groups. Knee flexion contracture improved only in the group with patellar lowering. Extension lag did not improve in either group. Peak knee flexion during the swing phase remained unchanged in both groups.

DISCUSSION

Patellar lowering is effective in diminishing minimum knee flexion at mid-stance in patients with patella alta and crouch gait due to cerebral palsy. Patellar lowering has not adverse effects on gait. These findings cannot be assumed to apply to patients with normal patellar height.

LEVEL OF EVIDENCE

IV (retrospective study).