Anteroposterior view: Supine position with fully extended knee and central X-ray beam directed vertically at a 5-7° cephalad angulation.
Notch (tunnel) view: Prone position with 40° knee flexion and the Xray beam is directed caudally toward the knee at a 40° angle from the vertical.
Weight-bearing AP view is preferable.
Standing flexion views at 30°-40° allows assessment of articular wear in deeper flexion that is may not be apparent on standard AP views in early degenerative knee arthritis.
Anterior view of right knee
AP Xray view of right knee
Anterior view of right knee
Anterior view of right knee
AP Xray view of right knee
Medial joint space narrowing with lateral joint space preservation.
Medial joint space narrowing with preservation of lateral compartment.
Assess tibia wear pattern and determine tibia slope
Valgus stress applied. Lateral joint space preservation.
Intact MCL (medial collateral ligament).
Varus stress applied demonstrating medial joint space narrowing. Intact LCL (lateral collateral ligament).
Lateral view: Lateral position with 30° knee flexion. The Xray beam is directed medially at 5°-7° cephalad angulation.
Axial CT view of the right knee
α Tibial tubercle-to-trochlear groove (TT-TG) distance.
Superimposed images used to calculate
TT-TG.
Insall-Salvati ratio
A/B: normal = 1 ± 0,2
Modified Insall-Salvati ratio
A/B High patella >2.0
Blackburn-Peel index
A/B: normal =0.8-1
Caton Deschamps index
A/B: normal mean = 1 (0,6-1,3)
1. Unicompartmental knee replacement. Bert J M. Orthop Clin North Am 2005; 36:513-522.
2. Unicompartment Knee arthroplasty. Borus T, Thornhill T. J Am Acad Orthop Surg 2007; 15: 9-18.