Guided growth for fixed knee flexion deformity.

BACKGROUND: Fixed knee flexion deformity (FKFD) is an insidious problem that may complicate the management of patients with neuromuscular compromise due to cerebral palsy, spina bifida, arthrogryposis, and other conditions. The energy costs associated with crouch gait may become prohibitive and, with the inexorable progression of fixed knee flexion, secondary pain may ensue as a result of fragmentation of the patella and/or tibial tubercle. Concomitant or compensatory flexion deformity of the hips and lumbar lordosis may develop, along with "pseudo equinus" of the ankles. Recommended treatments for FKFD have included bracing; physical therapy; and, in recalcitrant cases, distal femoral osteotomy, posterior release, or frame distraction. However, these latter modalities are fraught with potential complications including neurovascular damage, loss of fixation, undercorrection malunion, fracture, and recurrent deformity. Considering that FKFD is often bilateral, the complication risks for a given patient are doubled. In a previous study, the senior author reported successful hemiepiphysiodesis of the distal anterior femur using staples. However, further experience has demonstrated some of the limitations of stapling including relatively slow correction and occasional hardware migration. This led to the development of a more versatile and reliable solution using a pair of anterior tension band plates.

METHODS: In this retrospective clinical study, we are reporting this new technique of promoting gradual correction through guided growth of the distal femur, using a pair of anterior 8-plates. The correction is accomplished simultaneously and bilaterally, without immobilization, and may be combined with other operative procedures as indicated. We reviewed the charts, radiographs in a group of patients treated accordingly.

RESULTS: In this group of 18 patients with 29 deformities, we noted correction averaging 1.3 degrees (range, 0.0 [1 patient]-4.8 degrees), with minimal complications. No inadvertent coronal plane deformities were created. Upon full correction, the plates were removed so as to avoid recurvatum.

CONCLUSION: As an alternative to posterior capsulotomy or supracondylar extension osteotomy, we have found that guided growth is an effective and safe method of gradually correcting FKFD in growing children and adolescents.

LEVEL OF EVIDENCE: 4 (retrospective clinical series).