Current Concepts: Evaluation and Treatment of Discoid Meniscus in the Pediatric Athlete

TREATMENT

Management of symptomatic discoid meniscus is directed toward resolving symptoms while preserving meniscal tissue and preventing the development of OA. Incidentally found discoid menisci in asymptomatic patients should not be treated surgically and can have periodic follow-ups for detection of any functional deterioration or symptom development. Surgical treatment may be beneficial for patients with symptoms related to their discoid menisci such as pain, recurrent effusion, limited knee motion, mechanical symptoms (e.g., locking and catching), and activity restrictions.

Traditionally, surgical treatment of a symptomatic discoid meniscus consisted of subtotal (meaning nearly complete, or <3mm of peripheral rim remaining) or complete meniscectomy, often performed in an open fashion. Surgical techniques have evolved; current surgical approaches typically include diagnostic arthroscopy followed by arthroscopic saucerization (also called partial meniscectomy) of the central portion of the “disc,” leaving a peripheral rim of 6 mm to 8 mm to approximate that of the normal meniscus (Figure 2).^29,30 Saucerization removes the redundant central meniscal tissue in an attempt to create a more “normal” C-shaped morphology, although it does not address the increased thickness characteristic of many discoid menisci. It may be particularly difficult to “debulk” an abnormally thick discoid meniscus in the coronal plane, and there is little in the outcomes literature to support this approach. Following partial meniscectomy, the remaining meniscal tissue should be inspected thoroughly both for the presence of instability and for residual tears. Meniscal tears should be repaired in standard fashion; commonly, this may be a combination of all-inside sutures placed into the posterior horn, inside-out sutures placed into the midbody, and outside-in sutures placed into the anterior horn. Peripheral rim instability—identified, for example, by the ability to translate the posterior horn of the meniscus fully onto the anterior tibial plateau—should be addressed by suturing the meniscus to the adjacent capsule (Figure 2).^{25, 31} Menisci that have residual complex tears that are not amenable to repair may be treated by subtotal meniscectomy. These patients may be candidates for subsequent meniscal allograft transplantation.^32,33

TREATMENT OUTCOMES

Performing a partial meniscectomy has consistently been shown in the laboratory to increase contact stresses proportionally to the percentage of tissue removed.³⁴ It follows logically that performing a subtotal or complete meniscectomy in a young patient would yield increased, abnormal contact stresses throughout the knee with resultant degenerative changes and progression to OA over time. While long-term outcome studies of subtotal or complete meniscectomy have shown somewhat variable results, the majority report the development of pain, instability, poor function, osteoarthritic changes and even the development of osteochondritis desiccans.^5,35

In an early investigation of long-term outcomes associated with surgical resection of a discoid lateral meniscus, Räber and colleagues³⁶ retrospectively examined 17 knees that had undergone total meniscectomy for the lateral discoid meniscus. At a mean follow-up of 19.8 years, these authors reported that patients accounting for 10 of 17 operative knees had developed symptoms of osteoarthrosis such as pain. In addition, two-thirds of the knees that had follow-up radiographs performed (10 of 15 knees) had visible osteoarthritic changes present.

In 2011, Stilli and colleagues³⁷ conducted a mid-term follow-up study examining 104 knees over an average follow-up of 8.5 years, with an average age of 8 years at the time of surgery. Younger patients, 2 to 7 years, underwent subtotal meniscectomy whereas patients, 8 to 14 years, underwent arthroscopic partial meniscectomy. Patients with a Wrisberg variant underwent removal of the posterior horn. The authors of this study reported that younger patients who had undergone subtotal meniscectomy had the best outcomes (defined by self-reported questionnaire responses and clinical evaluation). However, these results should be interpreted with caution: at the time of follow-up, patients in this study would still have been in adolescence and may not yet have developed the symptomatic degenerative changes in the knee joint that are strongly associated with meniscectomy.

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