Zhao G, et al. - Researchers examined the value of preoperative neutrophil-lymphocyte ratio (NLR) as a predictor for recurrence of pigmented villonodular synovitis (PVNS) of the knee joint treated by arthroscopic surgery combining local radiotherapy. They examined 60 pathologically-proven PVNS cases of the knee joint from April 2006 to March 2017, all treated by arthroscopic synovectomy combined with adjuvant radiotherapy. A median of 52.8 months (7–138 months) of follow-up was carried out in all 60 patients. The estimated recurrence rate was about 23.3% (14/60). A significant difference in NLR was seen between the recurrent and non-recurrent group. Consequently, relapse in PVNS of the knee joint following the arthroscopic surgery combined with local radiotherapy was predicted by preoperative NLR in an easy and cost-effective manner.