Avoiding Injury to the Popliteal Neurovascular Bundle in All-Inside Suturing of the Posterior Horn of the Lateral Meniscus: A Magnetic Resonance Imaging Assessment of Portal Selection and Safety

Abstract

We assessed the risk of injury to the popliteal neurovascular bundle (PNVB) while suturing the posterior horn of the lateral meniscus (PHLM). We simulated all-inside suturing of the PHLM using magnetic resonance imaging of 60 knees. Lines were drawn from the medial and the lateral edges of the patellar tendon to the PHLM at increasing distances from the posterior cruciate ligament (PCL) to simulate suturing device trajectory. Distance from each line to the PNVB was measured (d). A similar analysis was performed using lines drawn from 1cm medial and 1cm lateral to the patellar tendon. We compared the average "d" at increasing distances from the PCL, between the different simulated portal entry points. We have also analyzed the association between different demographic characteristics and the shortest distance from the PVNB to the PHLM. Of 1200 measurements performed, the simulated suturing trajectory transected the PNVB 343 times (28.6%). At 0mm from the PCL, the safest portal was the 1-cm lateral portal (P < .001), with an average "d" of 2.7mm. At 3mm, 6mm, 9mm, and 12mm from the PCL, the safest portal was the 1-cm medial portal (P < .001), with average "d" of 3.8mm, 6.9mm, 10.1mm, and 13.5mm, respectively. Average distance between the PHLM and the PNVB was 7.8mm. Shorter distance between the PHLM and the PNVB was associated with younger age and female sex (P= .014 and .001, respectively). All-inside suturing of the PHLM at 0mm from the PCL is safer with a more lateral portal. Beyond 3mm from the PCL, a more medial portal carries a lower risk to the PNVB. Young and female patients have a shorter distance between the PHLM and the PNVB, suggesting a greater risk for injury to the PNVB. Careful preoperative magnetic resonance imaging assessment may assist in safer portal selection when planning repair of the PHLM. This study describes a magnetic resonance imaging-based risk assessment for injury of the PVNB while suturing the PHLM. It allows the orthopaedic surgeon a better understanding of the anatomic relationship between the popliteal neurovascular bundle and the lateral meniscus and can assist in portal selection and safety.