Meniscal healing: a biomechanical study.
Insight into the functional role of menisci has stimulated investigators to repair meniscal tears even in regions of poor vascularity. Data on scar strength resulting from different forms of therapy can be obtained applying biomechanical methods to animal models. With our new tear load propagation test, tissue strength in the scar as well as in the scar periphery was determined in rabbit medial menisci. Standardized longitudinal lesions localized in the microvascular zone II near the posterior horn were left untreated, fixed by suture, or sealed with fibrin glue. In two consecutive trials healing was determined after 6 weeks and after 12 weeks. After 6 weeks the mean scar strength was 19% (no therapy), 26% (suture), and 42.5% (fibrin glue) of the value measured in the equivalent region of the intact contralateral controls. In the peri-scar tissue in the line of the scar a section of secondary tissue weakness was discovered, which was shorter after treatment with fibrin glue. Although the scar strength was the same at Week 12, the area of tissue weakness was reduced. These biomechanical data point to the necessity of long-term studies to evaluate ultimate scar strength. They may explain the development of a bucket handle tear by extension of an initial lesion across an adjoining zone of secondary tissue weakness. The good results obtained with fibrin glue should encourage clinicians to use this therapy in clinical studies on meniscus repair in the inner zones of low healing capacity.