The common presumption that people with meniscal tears caused by trauma do better after arthroscopic partial meniscectomy than people with degenerative tears has been questioned by a study in this week’s The BMJ.

The Danish authors led by Associate Professor Jonas Bloch Thorlund from the University of Southern Denmark said systematic reviews and meta-analyses of randomised trials have concluded that arthroscopic knee surgery is no better than placebo surgery in middle aged and older patients with degenerative meniscal tears.

However, there were no corresponding randomised trials comparing non-surgical treatment with arthroscopic knee surgery for patients with meniscal tears of traumatic origin.

“Solid evidence from larger prospective studies using validated outcomes is lacking to confirm the current presumption that individuals with traumatic tears have larger improvements in patient reported outcomes after arthroscopic partial meniscectomy than those with degenerative tears,” they wrote.

The current research involving almost 400 patients aged 18 to 55 compared patient reported outcomes – measured by the knee injury and osteoarthritis outcome scores (KOOS) – at 7 days, 12 weeks and 52 weeks.

While the research team found a significantly larger improvement in KOOS scores—indicating better patient reported outcomes—for participants with degenerative tears it found no clinically meaningful difference in patient reported outcomes between the groups at all the time points measured.

Furthermore, a larger proportion of patients with traumatic tears said they were not satisfied with their knee function at 52-week follow-up, compared with participants with degenerative tears (63% v 52%).

And about 15% of participants were dissatisfied enough to consider that the treatment had failed, with no significant difference between groups (35% traumatic v 41% degenerative).

“Given the lack of effect of arthroscopic partial meniscectomy compared with placebo surgery for degenerative meniscal tears, and the positive effects of exercise for patients with degenerative meniscal tears…, the efficacy of arthroscopic partial meniscectomy for traumatic meniscal tears should be compared in controlled trials with placebo or non-operative treatment such as exercise,” the authors concluded.