[Rosenberg projection for the radiological diagnosis of knee osteoarthritis].

BACKGROUND Knee osteoarthritis is highly prevalent in our country. An early diagnosis is very important to provide an accurate and early treatment, and eventually delay its progression. AIM To compare the diagnostic yield for osteoarthritis of two projections in knee X ray examination. MATERIAL AND METHODS We evaluated 44 knees with conventional (AP weight-bearing, in full extension) and Rosenberg (PA weight-bearing in 45 degrees of flexion) X ray projections in 32 patients (24 women and 8 men), aged 26 to 78 years. All patients were symptomatic at the time of evaluation, with a suspicion of knee osteoarthritis. Both projections were analyzed and compared. RESULTS Joint space in the lateral compartment with conventional AP weight-bearing and Rosenberg projections were 8.6+/-11.5 mm and 7.8+/-10.9 mm, respectively (NS). The joint space for the medial compartment were 8.2+/-10.9 mm and 6.7+/-8.6 mm, respectively (p <0.05). CONCLUSIONS Rosenberg projection is more sensitive to detect knee joint space narrowing as compared with conventional AP weight-bearing projection, at least in the medial compartment of the knee. Therefore, Rosenberg projection should be included in the initial study of any patient with suspicion of knee osteoarthritis.