Proximal Fibular Epiphysiodesis or Resection May Alter Lower Limb Alignment in Growing Children

Background: Fibular head prominence causes prosthetic problems for children with below-knee amputations. It can be aggravated by a more proximal fibular location resulting from a mismatch in growth between the proximal fibula and tibia in tibial deficiency and tibiofibular synostoses. Proximal fibular epiphysiodeses or resections are commonly used to address prominence or for Marquardt amputation revisions. We hypothesize that these fibular procedures may affect limb alignment in growing children. Methods: A consecutive series of isolated proximal fibular epiphysiodeses (n=19) or resections (n=8) at 5 centers was retrospectively reviewed. All patients had below-knee amputations. Patients with procedures affecting alignment and those with closed proximal tibial physes were excluded. From existing radiographs, preoperative and ≥ 2-year follow-up medial proximal tibial angles (MPTA), anatomic distal femoral angles (aLDFA), and proximal fibular height were measured. Results: Following epiphysiodesis or resection of the proximal fibula, 14 of 27 tibias went into ≥4 degrees more valgus than preoperatively. Five tibias went into ≥3 degrees varus, and 8 tibias changed ≤2 degrees in either direction. Five of 27 femurs went into ≥3 degrees more varus, and 5 went into ≥3 degrees valgus. Seventeen femurs changed <3 degrees. As a result of proximal fibular epiphysiodesis, the proximal fibular height decreased >3 mm in 11 of 19 patients. Three proximal fibular heights increased by >3 mm. Five fibulas changed <3 mm. Of the 19 epiphyseodeses, 9 tibias (MPTA) and 10 femurs (aLDFA) changed alignment categories (varus, valgus, or normal). Eight fibular head resections changed alignment categories in 7 tibias and 3 femurs. Magnitude and rate of change could not be correlated with age at surgery (mean=9.1 y). At follow-up (mean=5.1 y), 14 of 27 patients were mature. Conclusions: Proximal fibular epiphysiodesis usually resulted in a more distal proximal fibular location. Most tibias were in varus before proximal fibular epiphysiodesis/resection and became more valgus, some excessively. Most femurs were in varus preoperatively and remained there. Although proximal fibular epiphysiodesis or resection may reduce the fibular head prominence, growing children may require close observation for subsequent changes in frontal plane lower limb alignment, especially progressive tibial valgus. Level of Evidence: Level IV.