[Knee capsulotomy for fixed knee flexion contracture]

This study aimed to assess the results of knee capsulotomy for correcting fixed knee flexion contracture in children with cerebral palsy (CP).

Thirty-five children (20 boys, 15 girls; mean age 13.5+/-2.5 years) with CP underwent posterior knee capsulotomy for 59 knees. Eleven patients had diplegia, one patient had hemiplegia, and 23 patients had quadriplegia. There were two community ambulators (3 knees), 19 household ambulators (33 knees), and 14 nonambulators (23 knees). Posterior knee capsulotomy was combined with hamstring lengthening (50 knees, 84.8%), rectus femoris transfer (10 knees, 17%), Achilles tendon lengthening (12 knees, 20.3%), and posterior cruciate ligament release (eight knees, 13.6%). The mean follow-up was 3.5+/-1.7 years.

Fixed knee flexion contracture significantly improved from 26.5+/-15.4 degrees to 17.0+/-15.5 degrees after posterior knee capsulotomy (p<0.0001). The mean improvement was 9.5 degrees. Popliteal angle significantly improved from 70.6+/-18.7 degrees to 48.2+/-19.9 degrees (p<0.0001). Ankle dorsiflexion did not differ significantly. At the end of follow-up, 38 knees (64.4%) had improved knee flexion contracture and 21 knees (35.6%) had recurrent flexion contracture (failure). Age and male gender were significantly associated with failure rate (adjusted odds ratio 0.78, 95% CI: 0.62-0.99 and 12.1, 95% CI: 2.37-61.7, respectively). Complications included transient sciatic nerve palsy in seven knees (11.9%), and wound dehiscence in two knees (3.4%). Revision was required in two knees (3.4%), and posterolateral corner reconstruction in one knee (1.7%).

Posterior knee capsulotomy is another option for the treatment of knee contracture in CP, resulting in a significant decrease in knee contracture with acceptable complications. However, failure rate is higher in boys, patients who are marginal ambulators, and in younger age group.