It is well known that acute traumatic MMPRT without OA should be repaired whenever possible to restore meniscal hoop tension and to prevent early arthritic progression [8, 9, 10, 11]. Unfortunately, a large proportion of MMPRT cases seen in clinical practice involve degenerative tears in middle-aged or older patients [11, 12]. Hence, surgical repair is not always feasible in the population at risk of these tears [10, 16] due to substantial degeneration of the meniscal tissue and concurrent OA [2, 3, 17].
This retrospective study compared two treatments, partial meniscectomy and conservative treatment, for degenerative MMPRT. Although overall improvement was observed in the clinical results of both groups without inter-group differences, partial meniscectomy resulted in increased progression of OA in the medial compartment; however, there was no difference in the survival rate after mid-term follow-up.
The treatment options for MMPRT include conservative treatment, meniscectomy, and surgical repair. Traditionally, patients with MMPRT undergo conservative treatment or meniscectomy . Meniscectomy can provide symptomatic relief, but in most cases, progression to degenerative OA does occur [3, 5]. Consequently, there has been a recent shift toward meniscal preservation along with surgical repair . Although the overall outcomes of surgical repair have been good in some studies [16, 27, 28], Bin et al. partial meniscectomy can be a good option for selected patients with good prognostic factors and for patients who are not eligible for surgical repair because of the poor quality of their meniscal tissue, those who are inactive, or those who are not willing to undergo surgical treatment [1, 28]. In our study, pain and functional outcomes at first visit were significantly worse in the meniscectomy group than in the conservative group. This indicates that the greater the pain intensity, the higher the likelihood of patients choosing surgical treatment over conservative treatment. However, both meniscectomy and conservative treatment resulted in significant improvements in pain and function scores as per the VAS and IKDC scores, respectively, with no inter-group differences after an average follow-up of 6.3 years. The lack of significant differences may be due to the improvement in symptoms, including mechanical pain, with time, regardless of the treatment modality. The lack of differences in clinical outcomes despite greater progression of OA in the meniscectomy group than in the conservative group might be because the follow-up duration was not enough to detect differences in clinical outcomes.
The most important finding of this study was that OA progression was more severe in the meniscectomy group than in the conservative group (p = 0.03). Similar to our study, Krych et al. reported that partial meniscectomy for degenerative MMPRT provides no benefit over conservative treatment in terms of halting arthritic progression [14, 29]. Similarly, early OA development is more likely to occur after meniscectomy than after non-operative treatment [30, 31]. Meniscectomy may increase the pressure on the residual meniscus, which may worsen any subsequent articular degeneration [5, 32]. In a study by Han et al. , after meniscectomy for MMPRT, progression of OA on radiological examination was noted in 35% of the patients at 5–6 years after surgery. Krych et al.  found that 54% of partial meniscectomy patients and 34.6% of non-operative patients showed conversion to TKA at a mean of 54.3 and 30.2 months, respectively. Contrary to other studies, our study showed that the survival rate was 99% at 5 years and 87% at 10 years after meniscectomy and 98% at 5 years and 88% at 10 years after conservative treatment, possibly because meniscectomy was performed only in patients without significant malalignment or osteoarthritic change.
This study has several limitations. First, it was a retrospective investigation of a small, nonrandomized case series; thus, a selection bias may be present. Moreover, the baseline pain and functional scores were low in the meniscectomy group because patients chose the treatment modality based on their symptoms and treatment characteristics. To overcome this, this study compared the degree of improvement from the baseline level to the final follow-up. Second, the follow-up period was not long enough to detect differences in the survival rate. Third, the high proportion of female patients in our study is a unique characteristic of Asian populations, who tend to have floor-based lifestyles. This reduces the extent to which our results can be generalized. Finally, we did not evaluate the progression of OA using MRI because of its high cost, despite the fact that MRI has greater accuracy than radiography. Despite these limitations, we tried to only include patients with degenerative MMPRT without significant malalignment and advanced OA to reduce selection bias to ensure objective evaluation of the effectiveness of meniscectomy for MMPRT.