Role of High Tibial Osteotomy in Chronic Posterior Cruciate Ligament and Posterolateral Corner Knee Instability

High tibial osteotomy (HTO) has traditionally been performed to correct the mechanical axis of the knee in patients with osteoarthritis (OA) of the medial compartment associated with pain and functional impairment; in these patients the restoration of the alignment was related to the regeneration of the articular cartilage that seemed apparently normal (Fujisawa et al., 1979; Odenbring et al., 1992). Recently, HTO has also become very popular is association with cartilage techniques and meniscal grafts (Noyes et al., 2004). In the past chronic knee instability and varus thrust have been considered a contraindication for HTO (Coventry et al., 1993; Naudie et al., 1999), but nowadays, chronic instability is an indication for HTO, because allows to correct both the coronal and the sagittal alignment, improving the function of an unstable knee. Soft tissue techniques alone, without correction of the alignment, often give poor results because a bone deformity overstresses them (Christel, 2003; Goradia & Van Allen, 2002; Insall et al., 1984; Neyret et al., 1993). Soft tissue destruction causes a decrease in neuromuscular joint control, which in time can worsen the malalignment (Lephart et al., 1998). Reconstruction of the Posterior Cruciate Ligament (PCL), without repair or reconstruction of the Posterolateral Corner (PLC), often gives poor results (Christel, 2003; Krudwig et al., 2002; LaPrade & Wentorf, 2002; Noyes et al., 2005; Strobel et al., 2000. Some Authors (Badhe & Forster, 2002; Coventry et al., 1993; Hernigou et al., 1987; Insall et al., 1984; Nagel et al., 1996; Naudie et al. 1999) have reported satisfying results after HTO in monocompartimental knee OA and varus alignment, whereas there are few studies about the results of HTO in the unstable knee [9,17,18]. Recent papers suggest to perform this procedure before soft tissue reconstruction for the treatment of a PCL/PLC deficient knee associated with varus malalignment, to improve function and stability (Badhe & Forster, 2002; Fowler et al., 1994; Goradia & Van Allen, 2002). HTO is also useful in the treatment of an Anterior Cruciate Ligament (ACL) lesion associated with a varus of the knee (Dejour & Bonnin, 1994; Dejour et al., 1994; Fowler et al., 1994; Lattermann & Jakob, 1996; Lerat et al., 1993; Neuschwander et al., 1993; Noyes et al., 1993, 1996, 2000).