The Danger Zone for Iatrogenic Neurovascular Injury in All-Inside Lateral Meniscal Repair in Relation to the Popliteal Tendon: An MRI Study

Abstract

Background: Lateral meniscal repair can endanger the nearby neurovascular structure (peroneal nerve or popliteal artery). To our knowledge, there have been no studies to evaluate the danger zone of all-inside meniscal repair through the anteromedial (AM) and anterolateral (AL) portals in relation to the medial and lateral edges of the popliteal tendon (PT). Purpose: To establish the risk of neurovascular injury and the danger zone in repairing the lateral meniscus in relation to the medial and lateral edges of the PT. Study Design: Descriptive laboratory study. Methods: Using axial magnetic resonance imaging (MRI) studies at the level of the lateral meniscus, lines were drawn to simulate a straight, all-inside meniscal repair device, drawn from the AM and AL portals to both the medial and lateral edges of the PT. In cases in which the line passed through the neurovascular structure, a risk of iatrogenic neurovascular injury was deemed, and measurements were made to determine the danger zones of neurovascular injury in relation to the medial or lateral edges of the PT. Results: Axial MRI images of 240 adult patients were reviewed retrospectively. Repairing the body of the lateral meniscus through the AM portal had a greater risk of neurovascular injury than repairs made through the AL portal in relation to the medial edge of the PT ( P = .006). The danger zone in repairing the lateral meniscus through the AM portal extended 1.82 ± 1.68 mm laterally from the lateral edge of the PT and 3.13 ± 2.45 mm medially from the medial edge of the PT. Through the AL portal, the danger zone extended 2.81 ± 1.94 mm laterally from the lateral edge of the PT and 1.39 ± 1.53 mm medially from the medial edge of the PT. Conclusion: Repairing the lateral meniscus through either the AM or the AL portals in relation to the PT can endanger the peroneal nerve or popliteal artery. Clinical Relevance: The surgeon can minimize the risk of iatrogenic neurovascular injury in lateral meniscal repair by avoiding using the all-inside meniscal device in the danger zone area as described in this study.

The Risk of Iatrogenic Peroneal Nerve Injury in Lateral Meniscal Repair and Safe Zone to Minimize the Risk Based on Actual Arthroscopic Position: An MRI Study

“…The weakness of this cadaveric study was that it did not evaluate the distances with the knee in the figure-of-4 position with appropriate varus force, which is the actual arthroscopic situation for lateral meniscal repair. The previous MRI study 5 evaluated the risk of iatrogenic peroneal nerve injury related to the medial and lateral borders of the PT with the knee in a slightly flexed position and found a risk of iatrogenic peroneal nerve injury in repairing the lateral meniscal tissue through both the anteromedial and the anterolateral portals related to both the medial and the lateral borders of the PT. They found that repairing the lateral meniscal tissue in relation to the medial border of the PT through the anterolateral portal was safer than through the anteromedial portal; however, the anterolateral portal was more dangerous than the anteromedial portal in repairing the lateral meniscal tissue in relation to the lateral border of the PT.…”

“…An all–inside meniscal repair device can endanger the peroneal nerve when the repair involves damage close to the medial and/or lateral borders of the PT and the tear type warrants meniscocapsular repair because the peroneal nerve is located at the posterolateral aspect of the knee joint. There have been several cadaveric and MRI-based studies that evaluated the risk of iatrogenic peroneal nerve injury during lateral meniscal repair 2,5,6,12,13,18,21 ; however, the results of these studies may not have accurately represented the true operative situation. The cadaveric studies may have been inaccurate because they all used midleg to midthigh cadaveric sections, which would have less than normal muscle and neurovascular tensions, and also were not evaluated in the actual surgical figure-of-4 arthroscopic position.…”

“…However, all previous cadaveric studies on meniscal repairs evaluated the peroneal nerve and/or posterior neurovascular structure of this area using midfemoral to midtibial knee joint specimens. 2,5,6,12,13,18,21 Several factors can influence the outcome of arthroscopic lateral meniscal repair, which could lead to inaccurate results from such cadaveric studies. First, when using a midthigh to midleg section, the tension from the various neurovascular structures, muscles, and tendons around the knees will be lower than the tension in a living person or a full-body cadaver.…”

“…2,6 For the MRI studies, the neurovascular risk of all-inside meniscal repair was assessed on preoperative MRI scans with the knee in extension or 90°of flexion with no joint dilatation, which involves different distances than the actual arthroscopic position (figure-of-4 with joint dilatation) (Figure 1). 1,3,5 To our knowledge, no previous studies have evaluated the risk of the iatrogenic peroneal nerve and popliteal artery injury based on the actual knee position during operation. The purpose of this study was to compare the risk of peroneal nerve injury in actual patients in ''reallife'' surgical positions when repairing the lateral meniscal tissue using the medial and lateral borders of the PT as references through the anteromedial, anterolateral, and transpatellar portals by measuring the closest distances from the tip of the simulated straight all-inside meniscal repair device to the peroneal nerve.…”

“…2,6 For the MRI studies, the neurovascular risk of all–inside meniscal repair was assessed on preoperative MRI scans with the knee in extension or 90° of flexion with no joint dilatation, which involves different distances than the actual arthroscopic position (figure-of-4 with joint dilatation) (Figure 1). 1,3,5…”