A Cross Sectional Study of Requests for Knee Radiographs from Primary Care

Background: Knee pain is the commonest pain complaint amongst older adults in general practice. General Practitioners (GPs) may use x rays when managing knee pain, but little information exists regarding this process. Our objectives, therefore, were to describe the information GPs provide when ordering knee radiographs in older people, to assess the association between a clinical diagnosis of osteoarthritis (OA) and the presence of radiographic knee OA, and to investigate the clinical content of the corresponding radiologists' report.

Methods: A cross sectional study of GP requests for knee radiographs and their matched radiologists' reports from a local radiology department. Cases, aged over 40, were identified during an 11-week period. The clinical content of the GPs' requests and radiologists' reports was analysed. Associations of radiologists' reporting of i) osteoarthritis, ii) degenerative disease and iii) individual radiographic features of OA, with patient characteristics and clinical details on the GPs' requests, were assessed.

Results: The study identified 136 cases with x ray requests from 79 GPs and 11 reporting radiologists. OA was identified clinically in 19 (14%) of the requests, and queried in another 31 (23%). The main clinical descriptor was pain in 119 cases (88%). Radiologists' reported OA in 22% of cases, and the features of OA were mentioned in 63%. Variation in reporting existed between radiologists. The commonest description was joint space narrowing in 52 reports (38%). There was an apparent although non significant increase in the reporting of knee OA when the GP had diagnosed or queried it (OR 1.95; 95% CI 0.76, 5.00).

Conclusion: The features of radiographic OA are commonly reported in those patients over 40 whom GPs send for x ray. If OA is clinically suspected, radiologists appear to be more likely to report its presence. Further research into alternative models of referral and reporting might identify a more appropriate imaging policy in knee disorders for primary care.