The Natural History of Medial Meniscal Root Tears: A Biomechanical and Clinical Case Perspective

Abstract

Posterior medial meniscus root tears (PMMRTs) make up a relatively notable proportion of all meniscus pathology and have been definitively linked to the progression of osteoarthritis (OA). While known risk factors for development of OA in the knee include abnormal tibial coronal alignment, obesity and female gender, PMMRTs have emerged in recent years as another significant driver of degenerative disease. These injuries lead to an increase in average contact pressure in the medial compartment, along with increases in peak contact pressure and a decrease in contact area relative to the intact state. Loss of the root attachment impairs the function of the entire meniscus and leads to meniscal extrusion, thus impairing the force-dissipating role of the meniscus. Anatomic meniscus root repairs with a transtibial pullout technique have been shown biomechanically to restore mean and peak contact pressures in the medial compartment. However, nonanatomic root repairs have been reported to be ineffective at restoring joint pressures back to normal. Meniscal extrusion is often a consequence of nonanatomic repair and is correlated with progression of OA. In this study, the authors will describe the biomechanical basis of the natural history of medial meniscal root tears and will support the biomechanical studies with a case series including patients that either underwent non-operative treatment (5 patients) or non-anatomic repair of their medial meniscal root tears (6 patients). Using measurements derived from axial MRI, the authors will detail the distance from native root attachment center of the non-anatomic tunnels and discuss the ongoing symptoms of those patients. Imaging and OA progression among patients who were treated nonoperatively before presentation to the authors will be discussed as well. The case series thus presented will illustrate the natural history of meniscal root tears, the consequences of non-anatomic repair, and the findings of symptomatic meniscal extrusion associated with a non-anatomic repair position of the meniscus.

Failed transtibial pullout repair of the medial meniscus posterior root

“…Meniscal root tears can result in loss of hoop strength, meniscal extrusion, rapid cartilage loss, and subchondral insufficiency fracture [3] . There are multiple treatment options for meniscal root tears including conservative management, meniscectomy, and surgical repair [ 1 , 2 , 4 ]. Treatment selection is based on multiple factors including patient age, symptoms, degree of cartilage deterioration, and chronicity of the tear [ 1 , 2 ].…”

Meniscus root tears: state of the art

“…They serve as shock absorbers by distributing the forces and converting the axial loads into radial tangential stresses, commonly referred to as hoop stresses [ 1 , 2 , 4 ]. Anchoring the meniscus to the tibia plateau and preventing meniscal extrusion during joint loading mitigate the impact of the compressive forces, consequently protecting the knee from potential osteoarthritic changes [ 10 – 13 ].…”

Meniscus Root Tears: A Clinical Review

“…Meniscus root tears are critical to recognize because they result in uniquely devastating consequences for the patient. In contrast to other meniscus tears that are more commonly discussed (degenerative, radial, horizontal, and bucket handle), the root tear results in rapid progression to advanced osteoarthritis (OA) in a short period and can be a more subtle diagnosis to make (1). The mechanism of injury and physical examination findings can be inconspicuous, which further increases the challenge of making this diagnosis (2).…”