Intra- and Extra-Articular Deformity of Lower Limb:Tibial Condylar Valgus Osteotomy (TCVO) and Distal TibialOblique Osteotomy (DTOO) for Reconstructionof Joint Congruency

Osteotomies are the established surgical procedure for the deformity of the lower limb induced by osteoarthritis (OA) of the kneeand ankle. Closed-wedge (CW) and open-wedge (OW) high tibial osteotomy (HTO) are extra-articular surgery, which aim to shiftthe mechanical axis from medial to slightly lateral and reduce the overload in the medial compartment of the varus deformedknee by extra-articular correction. However, varus deformity of the knee with the teeter effect, which could be accompanied withsubluxation and thrust due to the medial-lateral soft tissue imbalance, is not resolved only by the shift of mechanical axis. Thedepression of the medial tibia plateau, so-called pagoda deformity, is the intra-articular deformity, which could potentially causethe teeter effect and involves intra-articular incongruency. In such case, the osteotomy with novel concept should be developed toovercome the issues, both the imbalance of soft tissue and intra-articular deformity. Tibial condylar valgus osteotomy (TCVO) isan intra-articular osteotomy, which improves the joint congruency of the medial-compartment knee OA with subluxation and/orintra-articular deformity and also provides better joint stability. A similar argument is raised in the treatment of the ankle OA. Lowtibial osteotomy (LTO) is an extra-articular surgery to correct malalignment of lower leg. Distal tibial oblique osteotomy (DTOO)is a novel surgery to improve the bony congruency of the ankle OA. In DTOO, the distal tibia is cut obliquely from the proximalmedial to the distal lateral in the coronal plane and towards the center of the tibiofibular joint to improve the bony congruency ofthe ankle joint. Tibial condylar valgus osteotomy (TCVO) and distal tibial oblique osteotomy (DTOO) can correct intra-articulardeformity of knee and ankle, respectively. The rationale and indication of TCVO and DTOO for the treatment of the lower limb byreconstructing the joint congruency are discussed