Rosenberg et al. prospectively compared the 45-degree posteroanterior flexion weight-bearing knee radiograph against the conventional extension AP view. The gold standard was intraoperative arthroscopic grading in 55 surgical patients. The study asks: does imaging the knee under load at 45 degrees of flexion better reveal the cartilage loss that surgeons actually see inside the joint?
The standard extension AP knee radiograph images the anterior femoral condyle — not the zone where cartilage actually fails first. During weight-bearing activity, the femorotibial contact area sits at 30–60 degrees of flexion, posteriorly on the condyle. The conventional view was systematically missing the lesion.
When a patient has knee pain clinically suspicious for arthritis but a normal-appearing standard AP, add the Rosenberg view before concluding the joint is intact. A flexion view showing bilateral joint space narrowing to 1–2 mm is grade III–IV degeneration regardless of what the extension AP shows.
This view changes two concrete decisions. First, in any patient being considered for proximal tibial osteotomy, the Rosenberg view can reveal occult lateral compartment degeneration that would contraindicate the procedure. Second, before meniscectomy in a patient over 40, a Rosenberg view showing advanced cartilage loss predicts a poor outcome (Lotke et al. Reported only 21% success when preoperative radiographs showed osteoarthritis, vs. 90% with a normal preoperative film).
The view is not routine for every knee. It is a problem-solving tool when clinical suspicion and standard films are discordant.
Rosenberg et al. prospectively compared the 45-degree posteroanterior flexion weight-bearing knee radiograph against the conventional extension AP view. The gold standard was intraoperative arthroscopic grading in 55 surgical patients. The study asks: does imaging the knee under load at 45 degrees of flexion better reveal the cartilage loss that surgeons actually see inside the joint?
The standard extension AP knee radiograph images the anterior femoral condyle — not the zone where cartilage actually fails first. During weight-bearing activity, the femorotibial contact area sits at 30–60 degrees of flexion, posteriorly on the condyle. The conventional view was systematically missing the lesion.
When a patient has knee pain clinically suspicious for arthritis but a normal-appearing standard AP, add the Rosenberg view before concluding the joint is intact. A flexion view showing bilateral joint space narrowing to 1–2 mm is grade III–IV degeneration regardless of what the extension AP shows.
This view changes two concrete decisions. First, in any patient being considered for proximal tibial osteotomy, the Rosenberg view can reveal occult lateral compartment degeneration that would contraindicate the procedure. Second, before meniscectomy in a patient over 40, a Rosenberg view showing advanced cartilage loss predicts a poor outcome (Lotke et al. Reported only 21% success when preoperative radiographs showed osteoarthritis, vs. 90% with a normal preoperative film).
The view is not routine for every knee. It is a problem-solving tool when clinical suspicion and standard films are discordant.