Beletsky et al. conclude in their study:
The majority of patients undergoing APM achieve benefit within 6 months of surgery, with diminishing proportions at later timepoints.
This should not come as a surprise considering that arthroscopic partial meniscectomy (APM) has no proven efficacy as shown by numerous high quality RCTs which have included even sham-surgery as a control. I think not a single APM study should be published without acknowledging this fact.