Smoking and obesity influence the risk of nonunion in lateral opening wedge, closing wedge and torsional distal femoral osteotomies

Purpose: Lateral distal femoral osteotomies (DFO) have recently been performed more frequently. In addition to realignment for varus and valgus deformity, the indication was extended with the introduction of torsional osteotomies in patellofemoral instability. The purpose of this study was to assess the general and technical risk factors for nonunion in lateral opening, closing and torsional DFO. Methods: A total of 150 lateral DFO [98 opening wedge (LOWDFO) and 52 closing wedge (LCWDFO)] were analyzed in regard to potential risk factors for nonunion until plate removal. Nonunion was defined as failure of osseous consolidation according to clinical and radiological evaluation. Results: In LOWDFO, the nonunion rate was 2%, in LCWDFO the rate was higher with 9.6%. Nicotine abuse (p = 0.009) and a higher body mass index (p = 0.003) were significant risk factors. Patient’s age and gender, the wedge height, hinge fractures, monoplanar versus biplanar osteotomy as well as additional torsional osteotomies were not significant in regard of nonunion. Conclusions: Lateral DFO have a low rate of complications and nonunion. Smoking and obesity were significantly associated with the risk of nonunion. Hinge fractures, monoplanar technique or complete bone cuts of the opposite hinge in torsional osteotomies did not negatively influence the nonunion rate in DFO. Level of evidence: Level IV.