Meniscal tears: The effect of meniscectomy and of repair on intraarticular contact areas and stress in the human knee

Abstract

The role of the meniscus in load transmission across the knee has long been a subject of debate. In this study, we examined the biomechanical consequences of the operative treatments for bucket-handle and pe ripheral meniscal tears. Contact areas and instanta neous intraarticular pressure distributions were meas ured in two groups of human cadaver knees. In Group I, consisting of four knees, we created a bucket-handle tear involving the inner one-third of the meniscus, followed by partial, and then total meniscec tomy. Knees were tested in an Instron testing machine after each procedure, using a 400 pound load at 0° or 30° flexion. Contact areas and local stresses were measured using Prescale, a pressure-sensitive film. After partial meniscectomy, contact areas decreased approximately 10%, and peak local contact stresses (PLCS) increased approximately 65%. After total men iscectomy, contact areas decreased approximately 75%, and PLCS increased approximately 235%. In Group II, consisting of three additional knees, we created a 2 cm peripheral tear of the posterior meniscal horn, followed by open repair, arthroscopic repair, seg mental, and then total meniscectomy. Repair of the tear was accomplished with either vertically placed sutures by an open technique or horizontally placed sutures by an arthroscopic technique. Knees were tested in the neutral position in the Instron machine and contact areas and local stresses measured using Prescale. PLCSs and contact areas were found to be the same using either repair technique. There was, however, a 110% increase in PLCS after segmental meniscectomy of that portion of the meniscus involved in the peripheral tear. These data suggest that the meniscus does have a weightbearing role. Contact stresses increased in pro portion to the amount of meniscus removed and the degree to which the structure of the meniscus was disrupted. Furthermore, there was no difference in the weightbearing characteristics of the meniscus when repaired by open versus arthroscopic technique when the knee is loaded at 0° flexion.