Villegas, Diego F.

Meniscal attachments serve to anchor and transfer loads from menisci to the tibia. These ligamentous tissues are composed of collagen fibers, elastin, ground substance and water. Ligaments have a time- and history-dependent viscoelastic behavior due in part to the interaction of the water and the ground substance [1]. The movement of water within ligamentous tissue is limited because of charged proteoglycan molecules. It has been shown that some exudation of water is present during cyclic loading of ligamentous tissue [2]. The movement and its inhibition could lead to changes of pressure within the meniscal attachments. Therefore, the purpose of this study was to quantify the internal pressure in human meniscal attachments subjected to physiological loading. Since it is thought that the posterior attachment is subjected to both tension and compression, while the anterior attachment is primarily subjected to tension [3–5], we hypothesized that the attachments mechanical environment is dictated by the external loads, and hence, the posterior attachment would elicit higher pressures.

ABSTRACTThis study investigated the internal fluid pressure of human cadaver meniscal root attachments. A pressure micro‐sensor was implanted inside each attachment site. Tibiofemoral joints were compressed to 2× body weight at various flexion angles and pressure recorded for 20 min. The anterior cruciate ligament (ACL) was then transected and joints retested. Lastly, a longitudinal incision of the lateral posterior (LP) horn was made and the joint retested. Ramp pressure was defined as the pressure when 2× body weight was reached, and equilibrium pressure was recorded at the end of the hold period. The medial posterior (MP) attachment was subjected to greater ramp pressure than the medial anterior (p = 0.002) and greater equilibrium pressure than all other root attachment sites (p < 0.001). Flexion angle had a significant effect on pressure as full extension was greatest at ramp (p = 0.040). Transection of the ACL decreased ramp pressure in the LP attachment (p = 0.025) and increased equilibrium pressure (p = 0.031) in the MP attachment. The results suggest that repair strategies should be developed which reconstruct the MP attachments to be sufficient to withstand large pressures. Furthermore, since meniscal pressure is highest at full extension, this fact should be considered when prescribing rehabilitation following repair of an attachment. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1507–1513, 2013