The extent of laceration of circumferential fibers with suture repair of the knee meniscus
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Cannulas used with suture based meniscal repair techniques can potentially injure the load transmitting fibers of the meniscus. The subject of this study was to quantify this effect in a porcine in vitro model.
Materials and methods
From fresh frozen medial porcine menisci tissue specimens were harvested following the course of the peripheral circumferential fibers bundles. In the first part of the study the tissue samples were perforated with the cannulas of either a Fast Fix or a Rapidloc device or with an 18-gauge needle. The specimens were then visually inspected for fiber damage using low power microscopy and the mean size of the laceration was measured. Finally, the extent of the tissue laceration was indirectly determined using non-contact strain measurements of the samples before and after puncture.
When advanced with the cutting edge perpendicular to the fibers, the cannulas consistently cut the fibers while those were rather separated with the opposite orientation. It could be shown that specimens with a mean width of 8.1 mm lost 25% of the load transmitting cross section when being perforated two times with a Fast Fix device (P < 0.001). This effect is negated when the cannula was oriented in line with the fibers.
Cannulas used for suture based meniscal repair can cause a substantial laceration of the meniscal tissue. The effect strongly depends on the orientation of the cutting edge of the cannula relative to the course of the fibers and can thus potentially be avoided by an appropriate handling and design.