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.