Abstract
Radiological examination is a useful tool in assessing osteoarthritis (OA) in the knee. We have compared the extent of osteoarthritis in the knee graded on radiographs and by intraoperative observation to determine if there is significant difference with relevance to preop-erative planning.
Radiographs for fifty-eight patients were graded for OA under blind conditions using the Ahlback classification system and direct measurement of the medial and lateral joint spaces. Intraoperative assessment of the corresponding joint surfaces was performed under blind conditions by a separate surgeon and graded using the Outerbridge classification system.
OA was found to be more common in the medial compartment than the lateral, both on radiographs and intraoperatively. Spearman correlation coefficient for the medial compartment comparing joint space narrowing and intraoperative assessment was −0.545. For the lateral compartment the Spearman correlation coefficient was lower at –0.406. Positive predictive values for OA in the medial and lateral compartments on radiography were 90% and 66.67% respectively. Negative predictive values for OA in the medial and lateral compartments on radiography were 44.74% and 34.69% respectively.
Conclusion: We have demonstrated that although radiographs have reasonable to good accuracy at showing OA in both compartments the absence of OA on radiographs does not correlate well with the absence of OA in the knee. This is of importance when planning operations, particularly unicompartmental knee replacement, as intraoperative findings of bilateral disease will change the operation required.
The abstracts were prepared by Mr Tim Briggs. (Editoral Secretary 2003/4) Correspondence should be addressed to him at Lane Farm, Chapel Lane, Totternhoe, Dunstable, Bedfordshire LU6 2BZ, United Kingdom
