The historical treatment for symptomatic discoid lateral menisci, open total meniscectomy,5,7,15,36 is no longer performed, as studies have shown it increases contact stresses proportional to the amount of meniscus removed, with up to a 235% increase after total meniscectomy,37 predisposing patients to early degenerative changes and osteoarthritis.38-41
With an appreciation of the role of menisci as load distributors and joint stabilizers in cartilage nutrition, current treatments aim to preserve as much stable meniscal tissue as possible.5 Surgical management of Wrisberg-variant discoid lateral menisci involves posterior stabilization with or without saucerization.7,33,42 The goal of arthroscopic saucerization is to preserve healthy tissue and create a stable remaining meniscus (6-8 mm in width)2,7,43,44 that provides adequate shock absorption without retearing.10 Wrisberg-variant discoid menisci can be stabilized with use of all-inside sutures from the meniscus to the joint capsule (Figures 4A–4F) when there is sufficient residual meniscus to allow for suture fixation to the posterior capsule after débridement. In contrast, some prefer an inside-out technique, as described by Neuschwander and colleagues,7 with inclusion of a mini-open approach. Any meniscal tears are addressed at time of surgery, either by partial meniscectomy or repair. Relative indications for meniscal repair include longitudinal, vertical, nondegenerative tears that are within 3 mm of the periphery (vascular zone) and are less than 3 cm in length.45 However, the majority of tears in adults are degenerative cleavage tears outside the vascular zone and therefore not amenable to repair.45,46 Before surgery, patients treated with stabilization with or without saucerization are prescribed partial weight-bearing in a hinged knee brace with gradual range of motion to 90° by 6 weeks and return to sports in 3 to 4 months.
Clinical Results
As has been consistently demonstrated, the long-term outcomes of total meniscectomy are poor function39,40,47 and radiographic evidence of lateral compartment arthritis.48 Patients who previously underwent total meniscectomy should be offered meniscal allograft transplantation, as it may offset the increased peak local contact pressures in the lateral compartment10 and improve function.49
With an appreciation for the importance of meniscus preservation, more recent studies have found encouraging results for arthroscopic saucerization and stabilization of Wrisberg-variant discoid lateral menisci. For example, Woods and Whelan44 reported excellent results in 75% of patients at 37.5-month follow-up after open repair of discoid lateral menisci lacking posterior attachments. In another study, by Neuschwander and colleagues,7 4 of 6 patients who underwent arthroscopic repair of unstable discoid lateral menisci without posterior coronary ligaments had excellent outcomes. Although these studies demonstrated symptom resolution and lack of radiographic evidence of degenerative changes at midterm follow-up,50 additional long-term studies should be performed to determine whether saucerization and stabilization prevent the onset of lateral compartment osteoarthritis.
Conclusion
Abnormally mobile discoid lateral menisci can result in painful lateral snapping knee syndromes but are often challenging to diagnose clinically and with traditional static imaging. Dynamic ultrasonography with provocative maneuvers can reveal lateral meniscal subluxation, which often cannot be appreciated on MRI, allowing for timely stabilization and symptom resolution.
