Knee X-ray Radiology
Knee Xray Radiology
Normal bone anatomy of right knee
Medial view of right knee
Posterior view of right knee
Mechanical axis
Mechanical axis of lower limb
X-ray Knee
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
Xray Right Knee
Anterior view of right knee
Anterior view of right knee
AP Xray view of right knee
Standing flexion views
Standing weight-bearing flexion
Medial joint space narrowing with lateral joint space preservation.
Weight-bearing views
Standing AP
Medial joint space narrowing with preservation of lateral compartment.
Standing Lateral
Assess tibia wear pattern and determine tibia slope
Stress radiologic views
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.
Lateral view of the knee
Radiological Patellar views
- Standing anterior-posterior (AP) and lateral views
- Merchant view of patella
- CT in select cases (assess TT-TG)
Patellar position
- Sunrise view: Prone position with knee flexed to 115° the beam is directed at a 15° cephalad angulation toward patella.
- Merchant view: Supine position with 45° knee flexion the beam is directed at a 60° caudal angle through patella.
Normal Femur Trochlear
Normal Femur Trochlear
Axial CT view of the right knee
α Tibial tubercle-to-trochlear groove (TT-TG) distance.
Superimposed images used to calculate
TT-TG.
Patellar height
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)
Patellar Trochlear Dysplasia
X-ray assessment
Normal Femur Trochlear
Femur trochlear dysplasia
References
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.
