Inside-out medial meniscus suture: an analysis of the risk of injury to the popliteal neurovascular bundle.

ABSTRACT

PURPOSE: To assess the risk of damage to the popliteal neurovascular structures when inserting the needle through the posterior aspect of the knee during inside-out suture of the posterior horn of the medial meniscus. METHODS: The first stage of our study consisted of simulating a virtual meniscal suture during magnetic resonance imaging by tracing a line from 3 different points (located medially [MP], centrally [CP], and laterally [LP] to the patellar tendon) to the posterior horn of the medial meniscus. This procedure was undertaken both at rest and with valgus stress. The next phase involved the suture of the posterior horns of medial menisci taken from cadaveric specimens, the needle being inserted through 3 separate locations (again located medially [MP], centrally [CP], and laterally [LP] to the patellar tendon). Finally, the distance from each suture thread to the aforementioned neurovascular bundle was measured. RESULTS: During the magnetic resonance imaging study, the measured distances at rest were 26.4 mm for MP, 28.8 mm for CP, and 31 mm for LP, whereas those recorded with valgus stress were 21.7 mm for MP, 23.6 mm for CP, and 26 mm for LP. In the second phase of the study (cadaveric specimen suture), the distances obtained were 22.6 mm for MP, 27.6 mm for CP, and 33 mm for LP. CONCLUSIONS: Our results indicate that when the needle is inserted through the 3 points investigated into the posteromedial region of the knee (10 mm from the posterior horn of the internal meniscus) during inside-out suture, it is far enough from the popliteal neurovascular bundle for the maneuver to be performed with a reasonable safety margin. However, this margin can be increased further still if the needle is inserted into the joint through a point located laterally to the patellar tendon. CLINICAL RELEVANCE Inside-out suture performed 10 mm from the posterior horn of the internal meniscus through the portals studied offers a sufficient margin of safety to avoid damage to the popliteal neurovascular bundle.