We present four technical modifications of high tibial osteotomy which improve its safety and reproducibility. (a) Open wedge correction: opening wedge osteotomy from the medial side avoids lateral muscle detachment, dissection of the peroneal nerve, proximal fibula osteotomy, and leg shortening; only one osteotomy needs to be performed and the correction can be adapted intraoperatively. (b) Biplanar osteotomy: in addition to the transverse osteotomy of the posterior tibia a second ascending osteotomy in the coronary plane underneath the tibial tuberosity is performed. This provides improved rotational stability of the osteotomy and creates an anterior buttress against sagittal tilting of the osteotomy planes. (c) Incomplete osteotomy with plastic deformation of the tibia: 10 mm of lateral bone stock is left intact. The osteotomy is opened gradually over several minutes by sequential impaction of flat chisels or by use of a special spreading tool. Manifest fractures of the lateral cortex with resulting instability are avoided. Rapid bone healing is promoted. (d) Rigid fixation: stable osteosynthesis allows for early mobilization and avoids losses-of-correction. We use a medial plate-fixator which can be applied percutanously. In 112 patients operated on using this modified technique no pseudarthosis or loss-of-correction was observed.

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We conclude from these results that changes in tibial slope have a strong effect on cartilage pressure and kinematics of the knee. Therapeutically a flexion osteotomy may be used for decompression of the degenerated cartilage in the posterior part of the plateau, for example, after arthroscopic partial posterior meniscectomy. If a valgus osteotomy is combined with a flexion component of the proximal tibia, complex knee pathologies consisting of posteromedial cartilage damage and posterior and posterolateral instability can be addressed in one procedure, which facilitates a quicker rehabilitation of these patients.

Since a significant number of implant failures have been reported in association with the procedure of open wedge valgus high tibial osteotomy, the initial biomechanical stability of different fixation devices was investigated in this study. Fifteen third generation Sawbones composite tibiae were used as a model. Four different plates were tested: a short spacer plate (OWO) (n = 4), a short spacer plate with multi-directional locking bolts (MSO) (n = 5), a prototype version of a long spacer plate with multi-directional locking bolts (MSOnew) (n = 2), and a long medial tibia plate fixator with locking bolts (MPF) (n = 4). All opening wedge osteotomies were performed by the same surgeon (PL) in a standardized fashion. Axial compression of the tibiae was performed using a materials testing machine under standardized alignment of the loading axis. Single load to failure tests as well as load-controlled cyclical failure tests were performed. The required force and cycles to failure were recorded. Osteotomy gap motion was measured using linear displacement transducers. Residual stability after failure of the opposite lateral cortex was analysed. Failure occurred at the lateral cortex bone-bride in all tested implants. The rigid long plate fixator (MPF) resisted the greatest amount of force (2,881 N) in the single load to failure tests. In the cyclical load-to-failure tests, the constructs with MPF resisted more than twice the amount of loading cycles when compared to the short spacer plates. The osteotomy gap motion was smallest in the MPF, with a reduction of the displacements of up to 65, 66 and 88%, when compared to OWO, MSO and MSOnew, respectively. The highest residual stability after failure of the lateral cortex was observed in MPF as well. The results suggest that the implant design strongly influences the primary stability of medial opening wedge tibial osteotomy. A rigid long plate fixator with angle-stable locking bolts yields the best results.

New developments in osteotomy techniques and methods of fixation have caused a revival of interest of osteotomies around the knee. The current consensus on the indications, patient selection and the factors influencing the outcome after high tibial osteotomy is presented. This paper highlights recent research aimed at joint pressure redistribution, fixation stability and bone healing that has led to improved surgical techniques and a decrease of post-operative time to full weight-bearing.