SLR - July 2012 - Bryce Jolley
Reference: van Bergen C, Tuijthof G, Sierevelt I, van Dijk C. (2011). Direction of the oblique medial malleolar osteotomy for exposure of the talus. Arch Orthop Trauma Surg. 2011 July; 131(7): 893–901
Scientific Literature Review
Reviewed by: Bryce Jolley, DPM
Residency Program: North Colorado Podiatric Surgical Residency
Podiatric Relevance:
A medial malleolar osteotomy is an established approach for operative exposure of posteromedial osteochondral defects and fractures of the talar body. However, to obtain a congruent joint surface the osteotomy should be directed perpendicularly to the articular surface of the tibia at the intersection between the tibial plafond and medial malleolus. The purpose of this study was to determine this perpendicular direction in relation to the longitudinal tibial axis for use during surgery.
Methods:
To determine the optimal direction of the osteotomy, ankle radiographs and computed tomography (CT) scans were assessed. Using radiography, the intersection (i.e., angle between the tibial plafond and medial malleolar articular facet) was measured, and the tibial axis as a reference to the osteotomy direction was assessed. Two observers independently measured the intersection angle between the tibial plafond and medial malleolus in 46 ankles (45 patients) with an osteochondral lesion of the talus. The bisector of this angle indicated the osteotomy perpendicular to the tibial articular surface.
Results:
The intersection angle between the tibial plafond and the articular surface of the medial malleolus was measured 114.5 ± 6.3 degrees. The direction of the proposed osteotomy relative to the tibial axis was measured 30.4 ± 3.7 degrees. Forty (87 percent) of 46 ankles were measured within 5.0 degrees (i.e., 25.4 degrees–35.4 degrees) of the mean value. The intraobserver (ICC, 0.90–0.93) and interobserver (ICC, 0.65–0.91) reliability of these measurements were good to excellent.
Conclusions:
Radiographic measurements were used to determine preoperatively the optimal oblique medial malleolar osteotomy direction. The average osteotomy should be aimed 30 degrees relative to the tibial axis, in order to exit perpendicularly to the articular surface at the intersection between tibial plafond and articular facet of the medial malleolus.