Vascular safety during high tibial osteotomy: a cadaveric angiographic study.

Background: High tibial osteotomy is technically demanding. Risks include injury to the popliteal neurovascular bundle. The present goal was to further define this risk.

Hypothesis: The distance from the posterior tibia to the popliteal artery increases with increasing knee flexion. A saw angle perpendicular to the coronal plane can injure the popliteal artery.

Study Design: Descriptive laboratory study.

Methods: Seven fresh-frozen cadaveric lower extremities were used. Lateral radiographs at knee flexion angles of 90 degrees , 60 degrees , 45 degrees , 30 degrees , and 0 degrees were taken to measure the distance from the anterior border of the popliteal artery to the posterior cortex of the tibia 5.0 mm and 2.0 cm below the joint line. After an opening wedge high tibial osteotomy was made, qualitative assessments were made of the depth of a saw blade inserted into the kerf and the relative encroachment of the saw blade on the popliteal artery. The interval through which the space anterior to the popliteus can be accessed was identified by gross dissection in all specimens.

Results: The distance from the posterior tibia to the popliteal artery increased with knee flexion. At 5.0 mm and 2.0 cm below the joint line, the mean distance at 90 degrees was significantly greater than at all other angles. The popliteal artery could be injured by the oscillating saw at angles greater than 30 degrees to the coronal plane. A protective device inserted anterior to the popliteus protects the neurovascular structures.

Conclusion: The popliteal artery is farthest from the posterior tibia at 90 degrees of knee flexion. Saw angles greater than 30 degrees from the coronal plane put the popliteal neurovasculature at risk of injury.

Clinical Relevance: To perform a safe osteotomy, the knee should be positioned in 90 degrees of flexion with the saw angled less than 30 degrees from the coronal plane. A protective device deep to the popliteus may protect against popliteal injury.