Effect of Anatomic Variations in the Anterior Tibial Artery on Risk of Injury During Orthopaedic Knee Surgeries.

Background: Injury to the posterior vasculature is a potential complication in orthopaedic knee surgery that may be associated with variations in its anatomy, such as the type II-A2 variant, which places the anterior tibial artery (ATA) in closer proximity to the tibia. However, how close surgical instrumentation comes to injuring the ATA is not well described.

Purpose: To determine how the type II-A2 variant of the popliteal vasculature affects proximity of the ATA to instrumentation for orthopaedic knee procedures.

Study design: Cross-sectional study; Level of evidence, 3.

Methods: A total of 222 knee magnetic resonance imaging (MRI) scans from a single academic tertiary referral center were evaluated, and ATA branching patterns were characterized. The distances from the ATA to simulated instrumentation of high tibial osteotomy (HTO), posterolateral corner anatomic reconstruction, posterior cruciate ligament (PCL) reconstruction, lateral meniscus posterior horn repair, and lateral meniscus posterior root repair on axial plane MRI scans were measured by 2 authors independently using imaging software. Intrarater and interrater reliability of the measurements was calculated using the intraclass correlation coefficient.

Results: ATAs with the type II-A2 pattern passed anterior to the popliteus on 3.15% (n = 7) of the 222 MRI scans. The distance between the ATA and the simulated instrumentation was significantly closer in type II-A2 compared with normal (type I) knees for the lateral meniscus posterior root repair tunnel (11.1 vs 15.7 mm; P = .014), HTO cuts (0.6 vs 8.2 mm; P < .001), and PCL reconstruction tunnel (4.1 vs 11.7 mm; P < .001). Interrater reliability was good to excellent for all measurements, and intrarater reliability ranged from moderate to excellent.

Conclusion: HTO cut, PCL reconstruction tunnel, and lateral meniscus posterior root tunnel instrumentation were significantly closer to the ATA in knees with type II-A2 anatomy compared with normal (type I) anatomy. Careful analysis of vasculature using MRI may be of utility for select surgery about the knee to guide surgical technique.