Meniscal Extrusion: Diagnosis, Etiology, and Treatment Options

Abstract

Purpose of review: The concept of meniscal extrusion has recently been recognized as a hallmark of meniscus dysfunction. This review examines contemporary literature regarding the pathophysiology, classification, diagnosis, treatment, and future directions for investigation regarding meniscus extrusion.

Recent findings: Meniscus extrusion, defined as >3 mm of radial displacement of the meniscus, leads to altered knee biomechanics and accelerated knee joint degeneration. Meniscus extrusion has been associated with degenerative joint disease, posterior root and radial meniscal tears, and acute trauma. Meniscus centralization and meniscotibial ligament repair have been proposed as techniques to address meniscal extrusion with promising biomechanical, animal model, and early clinical reports. Further studies on the epidemiology of meniscus extrusion and associated long-term nonoperative outcomes will help to elucidate its role in meniscus dysfunction and resultant arthritic development. Understanding and appreciation for the anatomic attachments of the meniscus will help to inform future repair techniques. Long-term reporting on the clinical outcomes of meniscus centralization techniques will yield insights into the clinical significance of meniscus extrusion correction.

Keywords: Centralization; Meniscus extrusion; Meniscus tear; Root repair.

Fig. 1

Meniscotibial disruption on coronal MRI. Coronal preoperative MRI demonstrating medial meniscotibial ligament intact (left, arrow) and disrupted (right, red arrow), with meniscus extrusion (right, yellow arrow)

Fig. 2

Proposed pathoanatomy of medial meniscus extrusion. A Loading of meniscus increases hoop stresses. B Peripheral displacement of the meniscus alters contact pressures and tibial plateau cartilage coverage with injury to posterior meniscal root. C Posterior meniscal root integrity is lost with increased peripheral displacement of the meniscus. D Accelerated tibial plateau cartilage wear and bone overload secondary to a nonfunctional meniscus

Fig. 3

Diagram of meniscus centralization. Peripherally displaced meniscus in left picture is restored to its central position with an all-suture anchor placed at the periphery of the tibial plateau with the suture placed in a vertical mattress fashion through the peripheral rim of the meniscus in the right picture

Fig. 4

Suture anchor placement for medial meniscus centralization. A Elevation/release of the MT ligament with elevator (right knee, viewing from AM portal). B Anchor drill guide placed at the periphery of the MTP. C Deployed anchor with sutures exiting the accessory (acc) AM portal

Fig. 5

Suture passage through the meniscus. A Self-retrieving device from the anterolateral (AL) portal piercing the meniscocapsular junction to pass the repair suture. B Suture retrieved through AL portal. C Passing the shuttle suture

Fig. 6

Tightening of mattress sutures eliminates meniscus extrusion. A Suture shuttled under the medial meniscus (MM) by the shuttle suture, and retrieved through the anterolateral (AL) portal. B Remaining shuttle suture retrieved through AL portal. C Tensioning is performed. D Final construct

Fig. 7

Physical therapy and rehabilitation guidelines for meniscus centralization. Initial weight bearing is toe touch for 4 weeks with progression to WBAT starting at 4 weeks. Initial ROM is 0–90 in a brace for 4 weeks to protect centralization