Figure. Magnetic resonance imaging of the right knee.
A 57-year-old woman presents to the office with pain in her right knee that has persisted for 2 months. She notes that the pain is concentrated on the anterior knee and is intensified with repetitive knee bending. Physical examination reveals mild patellofemoral crepitus, mild joint effusion, and no joint line tenderness. Radiography is unremarkable for arthritis or any other abnormalities. Magnetic resonance imaging (MRI) is ordered, and sagittal views show moderate patellofemoral chondromalacia and a horizontal tear of the posterior horn of the medial meniscus (Figure).
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The natural course of a meniscus in older patients is degeneration and tearing over time.1 It is important to educate patients that meniscal tears are often found incidentally on MRI and may not be the cause of their knee pain.
In a 2010 study, investigators conducted MRIs on nearly 1,000 people aged 50 years and older with asymptomatic knees to look for meniscal tears in the right knee. A meniscal tear was found in 31% of patients. According to the authors, 61% of the subjects who had meniscal tears in their knees “had not had any pain, aching, or stiffness during the previous month.”2
The most common location of a meniscal tear was medial (66%) followed by lateral (24%), with 10% experiencing both medial and lateral tears. The study found that horizontal tears were the most common type (40%) followed by complex (37%) and then radial, oblique, longitudinal, and root tears occurring in 15%, 12%, 7%, and 1%, respectively.2
The prevalence of meniscal tears increased with age; patients aged 50 to 59 years had a prevalence of 32% in men and 19% in women, whereas patients aged 70 to 90 years had a prevalence of 56% in men and 51% in women. Arthritis was also a positive predictor of a meniscal tear. In the group of patients with severe arthritis, 95% of patients were found to have meniscal damage.2
The importance of this study is to educate patients that not all meniscal tears require surgery. Meniscal tears are often asymptomatic and found incidentally in patients aged >50 years, and they are often associated with degenerative arthritis.3 If arthritis is found on radiography or MRI in association with a meniscal tear, corticosteroid or viscosupplementation injection is an appropriate first step to determine if the arthritis is more symptomatic compared with the tear. Arthroscopic meniscectomy should only be considered for persistent knee pain that has failed conservative measures.2,3
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants.
1.Howell R, Kumar NS, Patel N, Tom J. Degenerative meniscus: Pathogenesis, diagnosis, and treatment options. World J Orthop. 2014;5(5):597-602.
2. Englund M, Guermazi A, Gale D, et al. Incidental meniscal findings on knee MRI in middle-aged and elderly persons. N Engl J Med. 2008;359(11):1108-1115.
3. Zanetti M, Pfirrmann CW, Schmid MR, Romero J, Seifert B, Hodler J. Patients with suspected meniscal tears: prevalence of abnormalities seen on MRI of 100 symptomatic and 100 contralateral asymptomatic knees. AJR Am J Roentgenol. 2003;181(3):635-641.