Abstract
The menisci function within the knee as load distributors, shock absorbers and secondary stabilisers. The medial meniscus has been shown to carry as much as 50% of the load across the medial compartment, and the lateral meniscus 70% of its compartmental load. After total meniscectomy, joint contact areas decrease by approximately 75%, and peak local contact stresses increase by as much as 235%. Meniscectomy may lead to a 14 times increase in the risk of arthritis at 20 years.
Axial load across the knee is converted into hoop stresses along the circumferential collagen fibres within the meniscus. Strong and stiff attachment of both meniscal horns, via the insertional ligaments, to the tibia is essential. Disruption of the circumferential fibre arrangement will defunction the meniscus. Preservation of meniscal tissue, where possible and appropriate, is now accepted practice.
Most techniques for meniscal repair have been validated in vitro by testing radial pull-out strengths. However, meniscal tissue is highly anisotropic, with little strength in the radial direction, perpendicular to the circumferential collagen fibres. Physiological forces in the radial direction, across the menisci, are probably only very small. Therefore, mechanical evaluation of radial pull-out strengths is probably of little clinical significance.
The role of different repair techniques, and the significance of gapping across repair sites under cyclical loading will be discussed.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
