You are playing tennis, cut left to return a down the line shot, but your knee decides to cut right instead. A quick twist, a pop, swelling, and pain – you’ve torn your meniscus. Tears of the meniscus are one of the most common injuries seen in orthopaedic practice, and arthroscopic treatment of meniscal injuries is the most common reason for surgical intervention for sportsmedicine trauma.
What is a meniscus tear and what defines appropriate management if you sustain this injury? The meniscus is a C-shaped cushion which sits on top of the tibia, or shin bone, within the knee. There are two menisci, one on the inside (medial) and one on the outside (lateral) aspect of the knee. The meniscus is composed of fibrocartilage, has a rubber-like consistency, and acts as a shock-absorber between the femur (thigh-bone) and the tibia. The primary purpose of your meniscus is to displace the forces transmitted between the femur and tibia during weight-bearing activities, decreasing the load on the articular cartilage (the white smooth cartilage that covers the ends of your bones). Loss of this articular cartilage is the primary factor in the progression of arthritis, and results in stiffness, pain, disability, and often leads to knee replacement surgery. Since the meniscus protects this cartilage, preservation of this tissue and appropriate management of tears is critical to long term knee function.
The meniscus has a relatively poor blood supply, with only the peripheral 1/3 (outer edge) having adequate blood vessels to permit healing. This predisposes the meniscus to tearing, and impairs healing when this occurs. Because neglect of these injuries may result in the loss of opportunity for surgical repair, evaluation by an orthopaedic surgeon is necessary when meniscal tears are suspected. Signs of a meniscal tear are pain, swelling, and mechanical symptoms (locking/catching) following a twisting or impact injury to the knee. Physical exam coupled with appropriate imaging studies are generally diagnostic. MRI evaluation has an accuracy approaching 95% for diagnosis of tears, and is the study of choice for these injuries.
Treatment depends on symptoms, age, activity level, and associated injuries. In general, meniscus tears following significant trauma in younger patients, especially when associated with ACL tears, have a higher likelihood of being repairable. Repairability is determined by the geometric pattern of the tear and the vascularity of the injured area. Younger patients are more likely to have simple tears in vascularized tissue, which have the capacity to heal when surgical repair is performed. Thus, in this scenario arthroscopic evaluation and possible repair should be considered after diagnosis is made. Through a minimally-invasive surgery, the meniscus is sutured together using arthroscopic instruments with minimal associated trauma. Meniscal repairs need to be protected from aggressive loading (i.e, sports) for at least 2-3 months. The goal here is to restore normal function and avoid long-term arthritic damage. When repair is precluded by the pattern of the tear, partial meniscectomy, removing the unstable portion of the meniscus while retaining as much intact tissue as possible, is the treatment of choice. If less than 30% of the meniscus is removed, risk of future arthritis is minimal. Return to sports after arthroscopic meniscectomy can be as soon as 2 weeks, with minimal dysfunction generally seen.
As we age, the meniscus progressively loses its blood supply, increasing the incidence of tears while decreasing their repairability. Consequently, about 50% of asymptomatic patients in their late 40’s who undergo MRI evaluation are seen to have degenerative meniscal tears. These are generally not amenable to repair and should be treated non-surgically initially. If mechanical symptoms and pain persist despite appropriate non-surgical management – anti-inflammatory medication, physical therapy, cortisone injection, activity modification – then arthroscopic meniscectomy may be considered. Patients need to be aware that meniscectomy will improve symptoms related to unstable meniscal tears, but may not improve those resulting from articular cartilage loss (arthritis). For patients with significant arthritic change seen on radiographs or MRI, more extensive surgical reconstruction – partial or total knee replacement – may be a consideration.
If you or your family member has a meniscal tear and needs treatment, call my office at (205) 271-6503 or (205) 802-6700 and we’ll get you taken care of. Have a great weekend!
Robert Wolf MD