Long-Term Effects of Complete Meniscectomy for a Discoid Lateral Meniscus
abstract & commentary
Synopsis: Complete meniscectomy for a discoid lateral meniscus leads to eventual arthrosis in most cases.
Source: Raber DA, et al. Discoid lateral meniscus in children. Long-term follow-up after total meniscectomy. J Bone Joint Surg Am 1998;80(11):1579-1586.
In approximately 1% to 17% of individuals, the lateral meniscus is discoid, with the central portion filled as opposed to the normal "C" shape. This discoid meniscus can be symptomatic, especially if the posterior meniscotibial attachment is not present. Patients usually present as children or adolescents, complaining of painful snapping on knee flexion and decreased ability to extend the affected knee.
Prior to the advent of arthroscopy, and even today for some unstable discoid menisci, treatment involved complete, open lateral meniscectomy. Raber and colleagues retrospectively evaluated 17 knees at a mean of almost 20 years following total meniscectomy. Four of the 17 were abnormal or severely abnormal using the International Knee Documentation Committee (IKDC) clinical rating system. Ten of 11 knees that were x-rayed showed radiographic changes of osteoarthrosis, although only four were moderately or severely painful with daily activities. Eight knees had also developed ligamentous instability. In total, only seven of 17 operatively treated knees were clinically normal and without subjective or objective symptoms over the long term.
Comment by David R. Diduch, MS, MD
A symptomatic discoid lateral meniscus is ideally treated by arthroscopic partial lateral meniscectomy, saucerization, or removal of the central portion so that the meniscus more closely resembles a normal "C" shape. Accomplishing this objective can be technically difficult due to the thickness of the tissue and obscured visualization at surgery. Discoid menisci without a posterior attachment (Wrisberg type) are frequently excised to avoid leaving an unstable rim. Successful repairs have been reported, but they have been restricted to case reports or small series of cases, as healing is difficult to achieve in an area that had no attachment to begin with.
The most significant finding by Raber et al was the high incidence of arthrotic changes found on x-ray. Other studies have noted a generally lower rate of arthrosis, ranging from 5% to 70%, but those studies were generally over a shorter term. The literature does tend to report greater arthrotic changes with studies having longer follow-up, as would be expected.1-3 Even though only four of 17 knees in this study were moderately or severely symptomatic, it is expected the clinical symptomatology will follow the observed x-ray changes with time.
This study effectively demonstrates that complete meniscectomy for a discoid lateral meniscus leads to eventual arthrosis in most cases. As such, total meniscectomy should be avoided whenever possible, being reserved only for those cases in which partial meniscectomy would leave an unstable posterior rim that is not amenable to repair.
References
1. Aichroth PM, et al. Congenital discoid lateral meniscus in children. J Bone Joint Surg Br 1991;73(6):932-936.
2. Washington ER, et al. Discoid lateral meniscus in children. J Bone Joint Surg Am 1995;77(9):1357-1361.
3. Wroble RR, et al. Meniscectomy in children and adolescents. Clin Orthop 1992;279:180-189.
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