[Structural changes in the lateral tibiofemoral compartment after high tibial osteotomy].

BACKGROUND: Valgus high tibial osteotomy (HTO) increases the pressure in the lateral tibiofemoral compartment. OBJECTIVE: The purpose of this work is to provide an overview about current knowledge on the effect of HTO on the lateral tibiofemoral osteochondral unit and lateral meniscus. MATERIALS AND METHODS: Studies in translational models on the effect of medial opening wedge HTO on the lateral tibiofemoral osteochondral unit and lateral meniscus are reviewed and placed in the clinical perspective. Emphasis is placed on specific correlations between topographical alterations of the cartilage, subchondral bone, and meniscus in the lateral tibiofemoral compartment. DISCUSSION: Specific topographical relationships exist in the central region between the articular cartilage and subchondral bone plate thickness, and in the submeniscal periphery between the articular cartilage and lateral meniscus, emphasizing the important protective role of the lateral meniscus. Following standard correction, the pressure increase in the lateral compartment following valgus HTO does not induce significant structural changes in the lateral tibiofemoral compartment. A higher increase in pressure following valgus overcorrection induces adaptive changes in the lateral compartment, reflected by an increased specific bone surface (BS/BV) in the subarticular spongiosa compared with unloading by varisation. Valgus overcorrection also leads to a decrease in the number of cells in the red-red (peripheral) zone of the middle third of the lateral menisci, without structural changes. RESULTS: In conjunction with the clinical data these results show that opening wedge HTO is a safe procedure for the lateral tibial osteochondral unit and the lateral meniscus.