The Outcomes of Distal Femoral Varus Osteotomy in Patellofemoral Instability: A Systematic Review and Meta-Analysis.

Distal femoral varus osteotomies have been novelly described in the recent years to be successful in the management of patellofemoral instability with genu valgum. However, these publications are limited to case reports and small case series and no published literature have attempted to analyze them in totality. The current review aims to pool together these small case series to evaluate the outcomes and complications of distal varus femoral osteotomies when performed for patellofemoral instability. The review was conducted using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. All studies that reported the outcomes of distal femoral varus osteotomy for patellofemoral instability were included. A total of five publications were included in the review, which included a total of 73 patients. All of the studies reported improvement in the radiological outcomes for genu valgum correction and patellofemoral instability. One study using opening wedge osteotomy reported a decrease in Caton-Deschamps index postoperatively, while another study using closing wedge osteotomy reported maintenance of the Caton-Deschamps index postoperatively. Second look arthroscopy showed an improvement in the status of the chondral lesions of the medial facet of the patellar undersurface, the lateral facet of the patellar undersurface and the trochlear groove 2 years postoperatively. All studies also reported a decrease in the risk of recurrence of patellofemoral instability, reduction in pain, and an improvement in all the clinical outcomes knee scores. Distal femoral varus osteotomy is promising and useful in the management of patellofemoral instability with genu valgum. The procedure can allow for radiological correction of the genu valgum and patellofemoral instability, reduction in the risk of recurrence of patellofemoral instability, reduction in pain, improvement in clinical knee outcome scores, and improvement in the status of the chondral lesions in the patellofemoral joint. It is highly versatile and could accommodate varying degrees of correction. These improvements in radiological and clinical outcomes can be seen in studies for both closing wedge and opening wedge distal femoral osteotomies. However, opening wedge osteotomies appear to decrease the patellar height as compared with closing wedge osteotomies which maintain the patellar height; therefore, the patellar height should be assessed preoperatively prior to deciding whether to perform an opening wedge or closing wedge distal femoral varus osteotomy. The Level of Evidence for this study is IV.