Meniscectomy

Ahmad F. Bayomy, MD

Semon Bader, MD

Richard D. Parker, MD

Paul M. Saluan, MD

Dr. Parker or an immediate family member has received royalties from Smith & Nephew and serves as a paid consultant to or is an employee of Smith & Nephew. Dr. Saluan or an immediate family member is a member of a speakers’ bureau or has made paid presentations on behalf of Arthrex, Inc.; serves as an unpaid consultant to Equalizer, LLC and Middle Path Innovations, LLC; has stock or stock options held in Equalizer, LLC and Middle Path Innovations, LLC; and serves as a board member, owner, officer, or committee member of the Pediatric Orthopaedic Society of North America. 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. Bayomy and Dr. Bader.

INTRODUCTION

Despite recent advances in meniscal repair and a greater understanding of the functional role of the meniscus, most symptomatic meniscal tears observed at arthroscopy remain irreparable. Meniscal tears may be simple radial, vertical/longitudinal, or horizontal in orientation. More complex patterns include displaced bucket-handle, parrot-beak, multiplanar, degenerative, and meniscal root tears (Figure 1). Tears most often involve the posterior horn of the meniscus. The work done to identify the vascularity of the meniscus has been helpful in classifying tears, with peripheral tears, or red-red tears, occurring in an area of good vascular supply. Red-white tears and the most central white-white tears have less vascular penetration (Figure 2).

The medial and lateral menisci occupy 60% and 80% of the articular surfaces in the medial and lateral compartments, respectively, and transmit forces across the joint.¹ The lateral meniscus plays a much greater role in force transmission than the medial meniscus; the medial meniscus provides secondary stability to anterior translation when the anterior cruciate ligament (ACL) is torn. When possible, preservation of the menisci should be attempted because their importance in load transmission and as secondary stabilizers has been widely demonstrated. At our institution, meniscal repair is the treatment of choice for red-red and red-white tears in young patients. Radial tears extending into the red-red and even the red-white zone are treated with an attempt at repair as well, with meniscectomy of the central white-white component.

The medial and lateral compartments of the knee appear to be affected to different degrees after meniscectomy. Because of the convexity of the lateral tibial plateau, point loading in the absence of the congruity imparted by the lateral meniscus leads to increases in peak contact pressures in the lateral compartment. This effect is not as profound in the medial compartment because of the relative maintenance of congruity, even in the absence of a medial meniscus.

Mid and long-term clinical studies have shown radiographic degenerative changes of the knee after meniscectomy.² The effect is multifactorial; however, the role of the meniscus in pressure distribution via hoop stress is important. Disruption of the circumferential collagen fibers within the meniscal tissue, typically radial in orientation or from meniscal débridement, can prevent the formation of the hoop stresses that develop in the meniscus as it is loaded and may effectively represent a subtotal meniscectomy even after limited débridement. Disruption to the posterior horn and root of either the medial³ or lateral⁴ meniscus may have more impact on loads than disruption of the circumferential fibers caused by radial tears limited to the central two-thirds of the menisci (Figure 3). The load-bearing mechanics do not appear to be as significantly affected with longitudinal or horizontal tears.

PATIENT SELECTION

Débridement of meniscal tissue should be undertaken in irreparable tears because of significant degeneration, fragmentation, or tearing in avascular tissue. Complex or frayed white-white tears have the least healing potential and are best served with appropriate partial meniscectomy. Stable, partial-thickness vertical tears less than 10 mm in length in the peripheral third may be treated with abrasion or trephination or left alone if showing healing. Patient compliance and family dynamics in younger patients play a critical role in postoperative management and should be taken into consideration because the indications to repair a meniscus are not absolute. The goal is to resect irreparable and/or unstable meniscal tissue, leaving a contoured and smooth remnant of tissue, ideally preserving over 50% of the meniscal rim.

Perhaps a more controversial indication for meniscectomy is that in patients with underlying degenerative arthritis. In 2017 the FIDELITY study group published
2-year follow-up of a randomized, blinded, multicenter trial of Finnish patients aged 35 to 65 years with atraumatic, degenerative meniscal tears and radiographic osteoarthritis who were assigned to arthroscopic partial meniscectomy (APM) versus sham surgery.⁵ Similar to the group’s 1-year follow-up data that received broad attention in The New England Journal of Medicine in 2013, there were not statistically significant differences between groups in terms of functional outcomes regardless of the presence of mechanical symptoms. Two systematic reviews with levels of evidence I, II, and IV published from 2016 to 2018 have supported the contention that APM leads to equivalent or worse outcomes than nonoperative management in patients with degenerative meniscal tears.⁶^,⁷ Accordingly, the indication for APM in adult patients with or without mechanical symptoms in the setting of osteoarthritis should be carefully evaluated and patients counseled accordingly.

FIGURE 1 Illustrations show meniscal tear morphologies. A, Radial tear. B, Radial root tear. C, Parrot-beak tear. D, Vertical/longitudinal tears. E, Horizontal tear. F, Bucket-handle tear. G, Root tear. H, Root avulsion.

FIGURE 2 Illustration of the vascular zones of the meniscus. The medial meniscus is on the left, and the lateral meniscus is on the right.

DIAGNOSIS

Clinical evaluation should include a comprehensive history and physical examination. Symptoms of a meniscal tear include knee pain; mechanical symptoms; and pain or swelling with activities of daily living, work, and/or sports. A knee effusion is frequently present and an important indicator and can be associated with reduction in quadriceps strength. Joint-line tenderness and positive McMurray, Apley grind, and Thessaly tests are also indicative of meniscal pathology. Loss of motion (particularly extension) may represent a displaced segment of meniscus. Discoid meniscal tears typically present in children younger than 10 years, often with symptoms of intermittent painful episodes of dramatic popping or snapping within the knee. Frequently, the child is unable to achieve full extension, and a “clunk” can be elicited on examination with flexion, extension, and circumduction.

PREOPERATIVE IMAGING

Standard radiographs should include 30° flexion lateral, Merchant, AP weight-bearing in extension, and 45° PA flexion weight-bearing views. Full-length weight-bearing radiographs can be used if malalignment is suspected and osteotomy is being considered. MRI, particularly 3-T
MRI, gives excellent visualization of meniscal pathology and is excellent for ruling out other intra-articular pathology (Figure 4). Preoperative MRI is useful for delineating tear morphology and location and helps in predicting the likelihood of repair versus débridement. Proton density-weighted, high-resolution, fast-spin-echo sequences are best for assessing both menisci and cartilage surfaces. Meniscal root tears require a higher index of suspicion, with meniscal extrusion being highly correlated.

FIGURE 3 Illustrations demonstrate the maintenance of hoop stress on the uninjured side and loss of hoop stress on the injured side due to a radial meniscal tear.

Radiographic indicators of discoid meniscus may include tibial spine hypoplasia, widening of the lateral joint line, or flattening of the lateral femoral condyle on PA view. On MRI, an abnormally thickened “bow tie” on the coronal view or greater than three cuts with continuity of the anterior and posterior horn on a 5-mm-thick sagittal cut view are diagnostic for discoid meniscus.

PROCEDURE

Setup/Equipment

In our institution, meniscal surgery is routinely performed on an outpatient basis. Patients are placed in the supine position under spinal, regional, or general anesthesia. Prophylactic antibiotic administration is variable among the orthopaedic surgeons at our institution. We typically do not use a tourniquet for routine arthroscopy. Preoperative examination under anesthesia is performed, focusing on ligamentous stability. Preoperative intra-articular injection varies among the authors of this chapter but incorporates 10 to 50 mL of 1% lidocaine or 0.25% bupivacaine, both with at least 1:400,000 epinephrine. We prefer preoperative injection to allow for clearance of the analgesic during arthroscopy because of concerns over chondrotoxicity from prolonged exposure. One of the authors incorporates 4 mg of intra-articular morphine in the preoperative injection; others add an injection of 4 mg of morphine at the completion of the case. We prefer a leg holder placed 5 to 8 cm proximal to the superior pole of the patella to maximize control of the limb; however, a post can suffice. The contralateral leg is placed in a well-leg holder, and the foot of the operating table is dropped. Additionally, a sequential compression device is used on the contralateral limb as a nonpharmacologic and relatively safe prophylactic measure for deep vein thrombosis (DVT).

FIGURE 4 Magnetic resonance images (3-T) show meniscal tears. A, Horizontal tear of the posterior horn extending to the inferior surface. B, Double posterior cruciate ligament sign, indicative of a displaced bucket-handle tear. C, Meniscal root tear (arrow) on coronal view. D, A tear at the root (large arrow) and extrusion of the meniscus (small arrow).

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