Meniscal Root Repair

Mitchell Meghpara, MD

Christopher D. Harner, MD

Dharmesh Vyas, MD, PhD

Dr. Harner or an immediate family member has received nonincome support (such as equipment or services), commercially derived honoraria, or other non-research-related funding (such as paid travel) from the Arthroscopy Association of North America, Donjoy, and Smith & Nephew and serves as a board member, owner, officer, or committee member of the American Academy of Orthopaedic Surgeons, the American Orthopaedic Association, the International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine, and the Musculoskeletal Transplant Foundation. Neither of the following authors nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter: Dr. Meghpara and Dr. Vyas.

INTRODUCTION

Meniscal root tears are a subset of meniscal injuries that are frequently unrecognized and can result in significant disorders in the knee.¹^,² These are radial tears located within 1 cm from the meniscal attachment on the tibia or root avulsion injuries.² Injuries to the root can result in loss of normal meniscus function, altered knee kinematics, meniscal extrusion, and increased peak contact pressures, which can be detrimental to the articular cartilage leading to early degenerative changes in the knee if not treated appropriately.²^,³^,⁴

It is important to recognize that both the medial and lateral posterior meniscal roots can be injured. Posterior medial meniscus root tears (MMRTs) are commonly degenerative and seen in middle-aged women.⁵ These can also be seen with iatrogenic injuries during posterior cruciate ligament reconstruction.⁶ Lateral meniscal root tears (LMRTs) can occur in 7 to 12% of patients with an anterior cruciate ligament (ACL) tear and are 10.3 times more likely to occur with an ACL tear than MMRTs.⁵^,⁷ In an ACL-injured patient, a LMRT was associated with anterolateral rotational instability and meniscus extrusion preoperatively.⁸ Thus, it is important to correctly diagnose these tears at the time of ACL reconstruction and repair them to help improve rotational stability and decrease peak contact pressures.⁹

PATIENT SELECTION

Indications for surgical management of meniscal root tears include (1) isolated symptomatic MMRTs with minimal arthritis, (2) failure of nonsurgical management with continued activity-limiting pain, and (3) lateral meniscal root tears concomitant with an anterior cruciate ligament (ACL) tear.

Contraindications to meniscal root repair are (1) medial joint space narrowing with Fairbank changes (on flexion weight-bearing PA radiographs), (2) asymmetric varus alignment (>3°) and medial joint space narrowing on long-cassette radiographs, and (3) diffuse International Cartilage Repair Society grade 3 or 4 chondral changes in the femoral condyle or tibial plateau articular cartilage identified at the time of surgery.

PREOPERATIVE IMAGING

Radiographs

Diagnostic imaging begins with plain radiographs. These include 45° flexion weight-bearing PA views of both knees, a lateral view, and Merchant patella views (Figure 1). These radiographs are used to gauge the amount of joint space narrowing in the three compartments: patella height (lateral), and patellar tilt, and subluxation (Merchant). A long-cassette AP view of the bilateral lower extremities is also obtained, and the overall limb alignment is determined by calculating the mechanical axis from the radiograph.

Magnetic Resonance Imaging

Based on the patient’s history and physical examination, if a meniscal tear is suspected, then a noncontrast MRI of the knee is obtained. The meniscal root can be easily identified on contiguous coronal images as a band of low-signal-intensity tissue anchoring the meniscus to the underlying tibia (Figure 2). Injury to the root varies from intrasubstance degeneration with mild fraying to full-thickness tears. A tear is identified by increased signal intensity within the meniscal root that extends to the articular surface on T2-weighted images. Additionally, root tears are often associated with extrusion of the meniscus more than 3 mm beyond the margin of the tibial plateau.¹⁰ In the presence of a complete radial tear, the two fragments may be separated and take on the appearance of an empty meniscal space or an empty meniscus sign.¹¹^,¹² Associated bone bruises and/or ligamentous injuries can also be identified on MRI.

PROCEDURE

Room Setup/Patient Positioning

The patient is placed supine on the operating room table, and prophylactic antibiotics are administered. A soft gel bump is placed under the ipsilateral hip, and a 10-lb
sandbag is taped to the table to support the knee at 90° of flexion (Figure 3). A lateral post is placed at the level of the midthigh to support the lower extremity. We do not use a tourniquet or a leg holder.

FIGURE 1 A 45° flexion weight-bearing PA view of both knees (A), a lateral view (B), and a Merchant patella view (C) demonstrate well-maintained joint spaces with mild early arthritic changes seen in the form of marginal osteophytes in all three compartments. Slight patella baja is also seen.

Special Instruments/Equipment/Implants

The procedure calls for the following equipment: