Geometric implications of the tibial wedge osteotomy for the treatment of cranial cruciate ligament disease in dogs

The tibial wedge osteotomy (TWO), a procedure that reduces the tibial plateau slope, has become an established surgical technique for the treatment of cranial cruciate ligament injuries in dogs, yet variation from the desired postoperative tibial plateau slope of 60 has been noted. The objectives of this study were to investigate the geometric implications of this procedure and to identify factors that affect the postoperative angles. The records of 35 consecutive cases that had a TWO performed were reviewed and comparisons were made between the alignment of the cortices and level of the osteotomy using duplicated tracings of a preoperative radiograph. The existing method for calculating the size of wedge to be removed was found to result in a postoperative slope greater than the expected 6 degrees. Our results indicate that the desired postoperative angle is more likely to be achieved if the cranial cortices are aligned and the osteotomy is performed proximally.