Meticulous preoperative planning is the key to accurate execution of corrective osteotomy. The need for well positioned radiographs or computed tomographic examination cannot be overemphasized. Measure the varus angle and determine the CORA from well-positioned radiographs. Compare this to the accepted normal value if available, or the opposite normal leg if present. If neither is available, the traditional recommendation is to perform a corrective osteotomy if the aLDFA exceeds 100 degrees. Other factors to consider are presence or absence of coexisting quadriceps alignment abnormalities or joint pathologies such as femoral torsion, medialization of the tibial tuberosity, shallow trochlear groove, and cranial cruciate ligament disease. In the absence of these, a smaller magnitude of femoral varus may be considered clinically significant; in other words, if no other factors that predispose to patellar luxation can be identified, corrective osteotomy may be the sole treatment indicated. In patientswith multiple limb alignment abnormalities and/or joint pathologies, a larger degree of femoral varus may be overcome with correction of the other predisposing causes. In large breed dogs with significant femoral varus, corrective osteotomy is generallyperformed along with correction of the other abnormalities as part of a comprehensive treatment plan.
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