Purpose of study: The aim of this project was to ascertain whether tibio-femoral joint space width (JSW) measured both on Schuss and full extension radiographic views were predictive and accurate relative to the articular cartilage findings on arthroscopy.

Methods & Results: The study was a prospective trial. The criterion for recruitment was knee pain indicative of arthritis that required arthroscopic assessment with a view to possible surgical management. Joint space narrowing (JSN) was assessed in the affected knee, in both the standing full extension and Schuss views. Joint arthroscopy was performed and each compartment area of the knee was calibrated and graded corresponding to the arthritic changes identified. In the 60 patients recruited, 61.7% were found to have grade 4 arthritic changes on knee arthroscopy. JSN in those with associated grade 4 changes on arthroscopy on either full extension or Schuss views was 75.7% and 78.4% respectively. However in 24.3% of those with grade 4 changes on arthroscopy no JSN was demonstrated on either full extension or Schuss views. Arthroscopic assessment of severe arthritic changes of the knee was significantly superior compared to the radiographic method (p< 0.05).

Conclusions: The findings suggest that despite narrowed JSW measured on either radiographic view being indicative of severe articular cartilage loss, neither view accurately predicts articular cartilage loss in less advanced cases. In cases of grade 4 changes and no JSN the sites of articular cartilage loss corresponded to sites that are less likely to be accurately represented on either radiographic view. Our findings suggest that knee arthroscopy may be better suited to identifying smaller patches of cartilage loss whose surface area may not be sufficient to cause JSN but may still cause symptoms. We suggest knee arthroscopy is indicated in patients with knee pain suspicious of arthritis but who lack obvious JSN on either full extension or Schuss views. This enables micro-fracture techniques to be used with the aim of attenuating disease progression, and offers a thorough lavage that may also provide symptom relief.