Managing the meniscus part I—Anatomy, biomechanics, and treatment strategies for the atraumatic meniscus tear

PURPOSE: The purpose of this article is to serve as the first of a two-part review on the meniscus; in this review, we will establish the background on anatomy and pathogenesis of the meniscus, as well as the effect of the meniscus on native knee kinematics and function. The atraumatic meniscus tear and its sequelae will be discussed, along with a discussion of various treatment strategies. METHODS: A literature search of online databases, journal articles, and book chapters were utilised to perform a narrative review on historical and current concepts related to the meniscus. We specifically evaluated the atraumatic meniscus tear, and included articles related to nonoperative treatment (i.e., exercise therapy, pharmacologic therapy, injections and orthobiologics) and operative management (i.e., meniscectomy, repair, meniscal transplantation and joint preservation procedures). Special preference was given towards journal articles published within the last 5-10 years to provide the most up-to-date literature. RESULTS: Atraumatic meniscus tears occur in both the medial and lateral menisci. There are a variety of subtypes of meniscal tears. The mainstay of diagnosis for atraumatic meniscus tears includes history, physical examination and radiographs. Magnetic Resonance Imaging is not necessary for diagnosis, yet provides further characterisation of tear patterns and concomitant injuries. Nonoperative treatment, such as lifestyle modification, exercise therapy, oral pharmacologic agents and injections (i.e., corticosteroids and hyaluronic acid) are effective first-line treatments. Biologic agents such as platelet-rich-plasma are becoming increasingly popular, but still require further, higher-level investigation. When nonoperative management fails, operative intervention including partial meniscectomy, meniscal repair, meniscal transplantation and joint preservation procedures can be utilised to improve pain and function. CONCLUSION: Differentiating atraumatic and traumatic meniscus tears is important for proper diagnosis and management. Many nonoperative modalities exist, yet ultimately operative intervention may be necessary to improve pain and prevent progression to knee osteoarthritis. LEVEL OF EVIDENCE: Level V, review article.