Biomechanical Evaluation of Lateral Meniscal Tears
Introduction
The majority of collagen fibers within the meniscus are circumferentially oriented. This orientation creates optimal resistance to hoop stresses, which displace the meniscus from the tibial plateau during weight bearing. Negative outcomes following meniscectomy have been well documented with long term studies of meniscectomized knees demonstrating clinical and radiographic arthrosis. Several studies have noted greater incidence of arthrosis after lateral meniscectomy when compared to medial meniscectomy. It has been suggested that a radially-oriented meniscal tear, which disrupts the primary, circumferential fibers of the meniscus, results in partial extrusion of the meniscus and abnormal load transmission equivalent to total meniscectomy. Furthermore, it has been demonstrated that partial radial tears of the medial meniscus do not result in significant increases in contact pressure compared to the intact meniscus, while contact pressures following partial radial tears are also significantly lower than those seen after partial medial meniscectomy. It is presently unknown whether partial radial tears of the lateral meniscus behave similarly to partial radial tears of the medial meniscus. To our knowledge, however, there have been no studies that investigate the biomechanical effects of isolated partial or complete radial tears of the lateral meniscus.
Historically, treatment options for radial tear of the meniscus have been limited. While partial meniscectomy has been the mainstay of treatment for radial tears, recently, 3 successful management with inside-out repair and all-inside repair of partial radial tears of the lateral meniscus has been reported. Whether similar results can be expected for complete tears of the lateral meniscus is presently unknown.
The purpose of the current study was to establish the pattern of biomechanical changes that transpire in the medial and lateral compartments after serial radial transection of the lateral meniscus. Our primary objective was to describe the alteration in load transmission and contact area in the lateral tibiofemoral compartment resulting from varying degrees of radial meniscal tear using a human cadaveric model. Furthermore, repair of complete radial meniscal tear was studied to determine whether normal load transmission and contact area would be restored. Finally, inside-out and all-inside meniscal repair techniques were compared.
The hypotheses of this study were that (1) radial meniscal tear result in disruption of meniscal function with decreased tibiofemoral contact area and increased contact pressure, (2) changes in contact area and pressure after complete radial meniscal tear approach those of total meniscectomy, (3) both repair techniques of the complete radial tear recreate normal load transmission across the lateral hemi-joint, and exhibit similar contact mechanics to the intact meniscus.
