Transmission of the Load in the Knee Joint with Special Reference to the Role of the Menisci

Abstract

The menisci of the knee joint transmit a considerable fraction of the total load acting on the joint. This paper describes an investigation into the load carrying capacity of the individual meniscus. Interest is also directed to an examination of the function of the degenerate meniscus and that of the meniscus with different kinds of tears. Quantifying the meniscal loads is based on a four-spring model representing the load bearing areas in the knee with intact menisci. The assumptions underlying the model are discussed and the problems of loading associated with the four-spring model are described. These problems called for careful consideration of the methods of loading and aligning the joint. A loading machine with a special aligning device was built for the experimental work. The experimental procedure is described in Part II. The intact individual meniscus was shown to transmit 70-99 per cent of the load acting on the respective side. The load carrying capacity of the meniscus was shown to decrease following the removal of a simulated ‘bucket-handle’ tear but in some cases it remained virtually unaltered. The stresses in the knee with redundant menisci were shown to increase by three to five fold their magnitude in the knee with intact menisci. Following removal of a simulated bucket-handle' tear, the stresses increased, but much less dramatically. The clinical implications of total and partial meniscectomy are discussed.