Despite widespread use, the benefit of knee arthroscopy for symptomatic osteoarthritis (OA) remains controversial. The theoretical benefit of removal of particulate debris and washout of inflammatory cytokines has not been supported by strong evidence. Arguments exist for its short term benefit in well selected patients. We sought to determine if arthroscopy provided any short term symptomatic relief in patients with a clinical diagnosis of OA in our unit.

A total of 20 patients were listed for routine arthroscopy over a one year period for OA. Mean age was 60 (range 48–74) years and 3 in 5 patients were female. 9 patients were listed by registrars, 6 by locum consultants and 5 by substantive consultants. One procedure was cancelled on the day of surgery due to lack of indication, with 19 knees proceeding to surgery. There was evidence of significant arthritis in 17 knees, 6 of which had associated degenerate meniscus tears. Two knees had meniscus tears without significant arthritis. All patients had washout and debridement and in addition, 8 partial menisectomies were carried out together with 3 loose body removals. Patients were followed up after an average of 12 weeks. The 2 patients (both male, mean age 52) with meniscus tears in the absence of significant arthritis fully recovered. Both had symptoms of true locking. 2 patients with loose bodies also fully recovered. With the exception of 2 patients with partial relief, the remainder had no symptomatic relief. One reported a worsening of symptoms and progressed to total knee arthroplasty.

These results suggest that arthroscopic debridement and washout plays a limited role in the short term symptomatic relief of OA. Surgeons should limit its use to younger patients with mild radiographic disease and true mechanical symptoms who are otherwise unsuitable for arthroplasty and not keen on undergoing joint conserving surgery.

Magnetic resonance imaging (MRI) is a useful diagnostic tool in evaluating meniscus pathology in the knee. Data from available literature suggests sensitivity and specificity rates around 90% when compared to the gold standard findings at knee arthroscopy. We sought to evaluate the sensitivity, specificity and precision rate (positive predictive value) of MRI at diagnosing meniscus tears within our unit.

A retrospective audit of a total of 79 MRI reports and arthroscopic findings spanning a one year period was carried out. There were 66 positive MRI reports and 13 negative reports. There were 6 false positives 4 false negatives when compared to arthroscopic findings. The sensitivity of MRI for detecting meniscus tears was 93.7% with 60 out of 64 tears detected. All 4 false negatives also had at least grade III osteoarthritic changes at arthroscopy. Specificity was rather low at 60% with MRI reporting 6 tears (false positives) out of 15 patients who had no tears found at arthroscopy. The positive predictive value (precision rate) of MRI detecting tears was 90.9%.

This data shows that MRI in our unit has a comparable high sensitivity to that in various literature making it a useful tool at ruling out disease with a negative result in the clinical setting. A more useful parameter in the clinical setting is its high precision rate when faced with a positive result. However, its specificity is much lower than that in most published data. A total of 6 tears on MRI turned out not to be on arthroscopy meaning patients could have been subjected to an avoidable invasive procedure in the absence of any other indication. This highlights the importance of obtaining reports from experienced musculoskeletal radiologists and the need for surgeons to review MRI images and match them to clinical information prior to subjecting patients to surgery.