BACKGROUND: The common peroneal nerve (CPN) is an important structure of the lower limb and is at risk of injury during total knee arthroplasty. The aim of this study was to use a tibial reference system to determine the position of the CPN relative to the knee center and popliteus. METHODS: Two hundred consecutive knee magnetic resonance images at the level of a standard tibial arthroplasty cut were evaluated for (1) distance of the CPN from the posterolateral capsule; (2) angle of the CPN from the center of the tibial anteroposterior axis; and (3) location of CPN with respect to the popliteus. RESULTS: The mean distance between the CPN and the posterolateral joint capsule was 11.9 mm (range, 4.7-22.13 mm), which correlated positively with the medial-lateral axis of the tibia (Pearson correlation, 0.157; P = .026) and negatively with the angle of the nerve from the midline (Pearson correlation, -0.237, P = .001). The mean angle of the nerve from the midline was 42.2° (range, 25.0°-64.0°). In 116 knees (58%), the CPN was in line with the popliteus from the center of the knee, in 69 knees (34.5%) the CPN was lateral to the popliteus, and in 15 knees (7.5%), the CPN was medial to the popliteus. A danger zone was identified as between 29.95° and 54.57° from the anteroposterior axis. CONCLUSION: The CPN is at risk during total knee arthroplasty. This study describes a method to help predict the location of the CPN intraoperatively and therefore avoid direct injury.
BACKGROUND: The common peroneal nerve (CPN) is an important structure of the lower limb and is at risk of injury during total knee arthroplasty. The aim of this study was to use a tibial reference system to determine the position of the CPN relative to the knee center and popliteus. METHODS: Two hundred consecutive knee magnetic resonance images at the level of a standard tibial arthroplasty cut were evaluated for (1) distance of the CPN from the posterolateral capsule; (2) angle of the CPN from the center of the tibial anteroposterior axis; and (3) location of CPN with respect to the popliteus. RESULTS: The mean distance between the CPN and the posterolateral joint capsule was 11.9 mm (range, 4.7-22.13 mm), which correlated positively with the medial-lateral axis of the tibia (Pearson correlation, 0.157; P = .026) and negatively with the angle of the nerve from the midline (Pearson correlation, -0.237, P = .001). The mean angle of the nerve from the midline was 42.2° (range, 25.0°-64.0°). In 116 knees (58%), the CPN was in line with the popliteus from the center of the knee, in 69 knees (34.5%) the CPN was lateral to the popliteus, and in 15 knees (7.5%), the CPN was medial to the popliteus. A danger zone was identified as between 29.95° and 54.57° from the anteroposterior axis. CONCLUSION: The CPN is at risk during total knee arthroplasty. This study describes a method to help predict the location of the CPN intraoperatively and therefore avoid direct injury.