Partial meniscectomy has been preferred in the treatment of discoid lateral meniscus (DLM) with tear, rather than total or subtotal meniscectomy, which could lead to late radiographic degenerative changes.

One or more risk factors contribute to radiographic progression of osteoarthritis after partial meniscectomy of DLM tear.

Inclusion criteria were consecutive patients who underwent arthroscopic surgeries for DLM tear from January 2005 to December 2010 by one surgeon. Exclusion criteria were preoperative osteoarthritis with KL grade 3 or more, osteochondritis dissecans, minimal width of meniscal remnant less than 6mm after meniscectomy, meniscal repair of an unstable discoid meniscus, age over 60years, loss to follow-up for a minimum of 5years and simultaneous surgery on articular cartilage or anterior cruciate ligament. According to the KL grade at the last follow-up, all enrolled knees were sorted into no progression to knee osteoarthritis (KL grade 1 or 2 – NOA) and progression to osteoarthritis (KL grade 3 or 4 – POA) groups. Multivariate logistic regression was used to analyze the risk factors of high-grade osteoarthritis.

In comparison with NOA group (n=135) and POA group (n=67), prolonged symptom duration, increased relative percentage of DLM thickness (RPDT) and the presence of horizontal tear were significant risk factors. The presence of horizontal tear (P=0.048, adjusted OR=19.364) was the strongest predictor, compared with prolonged symptom duration (P=0.030, adjusted OR=1.150) and increased RPDT (P=0.003, adjusted OR=1.377).

Horizontal tear, prolonged symptom duration, and increased RPDT are significant risk factors for radiographic progression to high-grade osteoarthritis after partial meniscectomy of DLM tear with a minimum follow-up of 5years.

III, case-control study.