Injury Risk to Extraosseous Knee Vasculature During Osteotomies: A Cadaveric Study With CT and Dissection Analysis

Background

Realignment osteotomies about the knee may be performed as distal femoral or proximal tibial osteotomies; both may be performed either on the medial or lateral sides of the knee, in closing- or opening-wedge fashion. Although rare, injury to neurovascular structures may occur, and the proximity of the vascular structures to the osteotomy saw cuts has been incompletely characterized.

Questions/purposes

We performed a cadaver study to assess the risk of vascular injury in patients undergoing realignment osteotomies by (1) quantifying the distances between osteotomy saw cuts and blood vessels using three-dimensional CT reconstruction after distal femoral and proximal tibial osteotomies; and (2) qualitatively describing the small- and medium-sized vasculature around the knee, to provide the link between the CT analysis and wedge incision measures, and better show the potential extraosseous supply to the regions investigated.

Methods

Twelve human cadaveric knees were injected with a latex and barium sulfate suspension into the superficial femoral artery. Each specimen underwent CT to evaluate vascular perfusion and was randomized to either a lateral opening-wedge distal femoral osteotomy and medial opening-wedge proximal tibial osteotomy group, or a medial closing-wedge distal femoral osteotomy and lateral closing-wedge proximal tibial osteotomy group. Postoperatively, knees underwent CT in extension to measure the shortest distance between the osteotomies and the popliteal artery, anterior and posterior tibial arteries, and genicular arteries. Vessels between 5 mm and 10 mm from the osteotomy cut were considered in a zone of moderate risk for damage, while vessels less than 5 mm from the cut were considered in a zone of high risk for damage. Vessels more than 10 mm from the cut were not considered to be at risk. Subsequently, knees underwent dissection and chemical débridement to qualitatively describe the smaller vessels. This part of the study added visual information and gave a comprehensive overview of the vessels at risk.

Results

All variations of the osteotomies put at least one artery at risk. The popliteal artery was found in a risk zone for injury in two specimens during closing-wedge distal femoral osteotomy (median distance, 11.6 mm; range, 5.2–14.6 mm). The superior lateral genicular artery was in a risk zone in all the specimens during opening-wedge distal femoral osteotomy (median distance, 3.0 mm; range, 0.7–6.5 mm), and in five specimens during closing-wedge distal femoral osteotomy (median distance, 4.5 mm; range, 1.3–11.2 mm). A concomitant risk for superior medial genicular artery injury was observed in five specimens during opening-wedge distal femoral osteotomy (median distance, 8.7 mm; range, 0.8–13.9 mm) and in four specimens during closing-wedge distal femoral osteotomy (median distance, 4.1; range, 0.5–41.7 mm). The popliteal artery was in a risk zone in four specimens during opening-wedge proximal tibial osteotomy (median distance, 9.6 mm; range, 6.6–12.9 mm), and in three specimens during closing wedge proximal tibial osteotomy (median distance, 9.6 mm; range, 4.4–11 mm). The inferior medial genicular artery could be classified at risk in five specimens during opening-wedge proximal tibial osteotomy (median distance, 2.1 mm; range, 0.3–32 mm) and in five specimens during closing-wedge proximal tibial osteotomy (median distance, 5.8 mm; range, 1.4–13 mm). Furthermore, the inferior lateral genicular artery was found in a risk zone in two specimens of closing-wedge proximal tibial osteotomies (median distance, 17.4 mm; range, 8–23.3 mm). There were no differences between opening-wedge and closing-wedge distal femoral osteotomies and proximal tibial osteotomies in the vessels at risk during the procedure. After chemical débridement, knees showed abundant vascularization of the distal femur and lateral tibia, whereas the medial tibia contained few arteries.

Conclusions

With the numbers available, we found that none of the osteotomy techniques performed was safer than any other in terms of the proximity of the major arterial structures and some vessels appear to be at relatively high risk during these procedures.

Clinical Relevance

This study clarifies that the genicular arteries on the opposite side of the surgical field, which cannot be seen and protected during the procedure, can be at risk of injury, particularly when the cortical hinge is compromised. Additional studies are necessary to address the potential risk of the dissection needed for plate placement and injuries related to drilling and screw placement during osteotomies around the knee.     

Screw fixation of the syndesmosis alters joint contact characteristics in an axially loaded cadaveric model

BackgroundThe purpose of this study was to quantify the effects of rigid syndesmotic fixation on functional talar position and cartilage contact mechanics.MethodsTwelve below-knee cadaveric specimens with an intact distal syndesmosis were mechanically loaded in four flexion positions (20° plantar flexion, 10° plantar flexion, neutral, 10° dorsiflexion) with zero, one, or two 3.5-mm syndesmotic screws. Rigid clusters of reflective markers were used to track bony movement and ankle-specific pressure sensors were used to measure talar dome and medial/lateral gutter contact mechanics.ResultsScrew fixation caused negligible anterior and inferior shifts of the talus within the mortise. Relative to no fixation, mean peak contact pressure decreased by 6%–32% on the talar dome and increased 2.4- to 6.6-fold in the medial and lateral gutters, respectively, depending on ankle position and number of screws.ConclusionsTwo-way ANOVA indicated syndesmotic screw fixation significantly increased contact pressure in the medial/lateral gutters and decreased talar dome contact pressure while minimally altering talar position.