The Teramoto distal tibial oblique osteotomy (DTOO): surgical technique and applicability for ankle osteoarthritis with varus deformity.

We have devised a medial peri-articular osteotomy, the distal tibial oblique osteotomy (DTOO), and have used this technique since 1994 for ankle osteoarthritis of advanced and late stages associated with varus inclination. This report describes the surgical technique and its applicability. DTOO can be used for cases of varus ankle osteoarthritis with a range of the ankle joint movement of at least 10° or more. The osteotomy is obliquely directed cut across the distal tibia from proximal-medial to distal lateral and is of an opening-wedge type with the centre of rotation coincident with the centre of the tibiofibular joint. A laminar spreader instrument is inserted in the osteotomy to open the wedge until the lateral surface of the talar body is seen on X-ray to be in contact and congruent with medial articular surface of the lateral malleolus. Common obstacles which may prevent this contact and congruency are bony spurs present on the anterior side of fibula or on the lateral side of the tibia; these require removal. The opening-wedge osteotomy is held in position by an Ilizarov external fixator or internally fixed with a plate. Bone graft is taken from the iliac crest and inserted into the open wedge. If, after completion of the osteotomy, the dorsiflexion angle of the ankle joint does not exceed 0°, a Z-lengthening is performed of the Achilles tendon. In the DTOO for ankle osteoarthritis, the contact area of the ankle joint increases and decreases the load pressure per unit area. Furthermore, as the width of the ankle mortice is restored through the realignment of the body of the talus, instability at the ankle joint decreases. There is additional improvement with restoration of the inclination of the distal tibial articular surface as this directs the hindfoot valgus and corrects the alignment of the foot, with consequent improvement of ankle pain.