[Open valgus alignment osteotomy of the proximal tibia with fixation by medial plate fixator]

High tibial osteotomy (HTO) is an established technique for the treatment of the symptomatic varus malaligned knee. Correction is usually achieved by closed wedge osteotomy from a lateral exposure. This procedure has a certain risk potential regarding peroneal nerve injuries, instability of the osteotomy and secondary loss of correction. We present four technical modifications of HTO which improve safety and reproducibility of this operation. 1) Open wedge osteotomy from a medial exposure 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. 2) A biplanar osteotomy provides improved rotational stability of the osteotomy and creates an anterior buttress against sagittal tilting. 3) An incomplete osteotomy with plastic deformation of the intact lateral bone bridge avoids fractures of the lateral cortex and instabilities and promotes bone healing. 4) Rigid fixation with a medial plate-fixator (Tomofix) allows for early mobilisation and avoids loss-of-correction. 262 patients were consecutively operated using the described modified technique until now. No loss-of-correction occurred in this group, two patients with delayed healing received secondary cancellous bone grafts.