Assessing the relationship of the peroneal nerve to the posterolateral corner of the knee and influence of race on its dimensions- A MRI based study in Indian population.

Background: The relationship of Common peroneal nerve (CPN) to the posterolateral corner of the knee joint is important for surgeons who perform total knee arthroplasty to avoid injury to the nerve during surgery. This relationship varies among different races on account of anthropometry. This study aims to evaluate the anatomical location of this nerve in Indian patients using an MRI based reference system.

Methods: 213 knee magnetic resonance images (MRIs) were evaluated in axial plane 8 mm below the joint line for distance of the CPN from the closest posterolateral capsule. The angle of the CPN from the center of the tibial anteroposterior axis and relation of CPN with respect to the popliteus were evaluated. A comparative analysis of these measurements among Caucasian, Chinese and Indian patients was made to evaluate for any differences.

Results: The mean distance between the CPN and the knee capsule was 15.55 mm (range, 7.8-26.2 mm). The mean angle of the CPN from the center of the AP axis was 50.1° (range, 38-63). CPN was found to be in line with the popliteus from center of the knee in 62% cases. There was no significant difference among the different races among the measured parameters (p > 0.005).

Conclusion: This study establishes a "danger zone" and a "safe zone" to avoid CPN injury in total knee arthroplasty in Indian patients and identifies anatomic landmarks to localize the nerve before the soft-tissues release in order to avoid direct injury.