Evaluation of popliteal artery injury risk with locked lateral plating of the tibial plateau

OBJECTIVES:: This study was undertaken to determine if there is increased likelihood of popliteal artery injury as one places a fixed-angle lateral proximal tibia locking plate with posterior plate lift off and or anterior plate translation from the ideal position. METHODS:: A Synthes (Synthes USA, West Chester, PA) 3.5-mm and 4.5-mm lateral proximal tibia locking plate was placed consecutively on each of six specimens in the straight lateral (SL) position. Screw position with respect to the medial cortex was recorded as well as the distance of the posterior most screw tip to the popliteal artery. Next a 3-mm shim was placed under the posterior edge of the same plate to mimic posterior plate lift off (LO) followed by placement of a 6-mm shim. The same experiment was repeated with the plate translated 5 mm anteriorly (AT). RESULTS:: The popliteal artery was injured in zero of six specimens using the 3.5-mm plate. The popliteal artery was injured in six of six specimens using the 4.5-mm plate in the 5-mm AT 6-mm LO position, five of six with 5-mm AT and 3-mm LO, two of six with only 5-mm AT, four of six with SL and 6-mm LO, two of six with SL and 3-mm LO, and zero of six with SL. CONCLUSION:: The Synthes 4.5-mm plate can put the popliteal artery at risk with as little as 3-mm posterior liftoff in the intended straight lateral position or with 5-mm anterior plate translation with no posterior liftoff. Therefore, placement of the 4.5-mm plate in the proper position and confirmation of its position with a true lateral radiograph is paramount to avoid injury to the popliteal artery.