What Is the Optimal Minimum Penetration Depth for “All-Inside” Meniscal Repairs?

Abstract

To identify desired minimum depth setting for safe, effective placement of the all-inside meniscal suture anchors. Using 16 cadaveric knees and standard arthroscopic techniques, 3-dimensional surfaces of the meniscocapsular junction and posterior capsule were digitized. Using standard anteromedial and anterolateral portals, thedistance from the meniscocapsular junction to the posterior capsule outer wall was measured for 3 locations along the posterior half of medial and lateral menisci. Multiple all-inside meniscal repairs were performed on 7 knees to determine an alternate measure of capsular thickness (X2) and compared with the digitized results. In the digitized group, the distance (X1) from the capsular junction to the posterior capsular wall was averaged in both menisci for 3 regions using anteromedial and anterolateral portals. Mean distances of 6.4 to 8.8mm were found for the lateral meniscus and 6.5 to 9.1mm for the medial meniscus. The actual penetration depth was determined in the repair group and labeled X2. It showed a similar pattern to the variation seen in X1 by region, although it exceeded predicted distances an average 1.7mm in the medial and 1.5mm in the lateral meniscus owing to visible deformation of the capsule as it pierced. Capsular thickness during arthroscopic repair measures approximately 6 to 9mm (X1), with 1.5 to 2mm additional depth needed to ensure penetration rather than bulging of the posterior capsule (X2), resulting in 8 to 10mm minimum penetration depth range. Surgeons can add desired distance away from the meniscocapsular junction (L) at device implantation, finding optimal minimal setting for penetration depth (X2+ L), which for most repairable tears may be as short as 8mm and not likely to be greater than 16mm. Minimum depth setting for optimal placement of all-inside meniscal suture anchors when performing all-inside repair of the medial or lateral meniscus reduces risk of harming adjacent structures secondary to overpenetration and underpenetration of the posterior capsule.