Growth modulation for fixed flexion contracture of the knee: a comparison of two techniques

Growth modulation has become a mainstream treatment for frontal plane angular lower extremity deformities in children. Few articles address the effect of growth modulation on sagittal deformity. Our aim is to compare two anterior distal femoral growth modulation techniques for fixed knee flexion contracture. Electronic medical records were reviewed for patients who underwent anterior femoral growth modulation for fixed flexion contracture. Patients were excluded if adequate preoperative/postoperative radiographs were unavailable. A cohort was subdivided based on surgical technique: screws alone versus dual tension-band plates. Complications were recorded; radiographs were evaluated preoperatively and at hardware removal. Posterior distal femoral angle (PDFA), posterior proximal tibial angle (PPTA), and anterior cortical line (ACL) angle were evaluated. Of 35 patients identified, 20 patients (29 knees) were included. Thirteen knees were treated with dual anterior tension-band plates; 16 knees had transphyseal screws. Sagittal alignment improved in both groups. Statistically significant PDFA changes were observed in the tension-band plate group (P = 0.0095); a trend was noted toward improvement in ACL angle (P = 0.08). PPTA did not change. No changes reached significance in the transphyseal screw group (PDFA: P = 0.181, ACL: P = 0.64). Tension-band plate migration was noted in one (7.7%) of 13 knees, and transphyseal screw migration in nine (56.3%) of 16 knees (P < 0.01). Anterior distal femoral growth modulation improves sagittal alignment without significant remodeling at the proximal tibia. Hardware migration occurred more often with transphyseal screws (P < 0.01). We recommend dual anterior tension-band plating over placement of paired screws for sagittal growth modulation to treat knee flexion contracture.