الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 72 |  |  |
| | | from | 72 | | |
Abstract
Knee alignment is best assessed by radiography of the hip, knee, and ankle when the subject is standing upright to support body weight. We use a frame and turntable so that once subjects have been set up they can be passively rotated through 90 ° for frontal or lateral views without disturbing the positioning.
The mechanical axis of the lower limb extends as a line from the heel to the hip the hip-knee-ankle (HKA) angle describes how the two long bone mechanical axes are lined! up with each other. Normally the knee center is close to the LBA, so that the ground reaction force tends to pass through the knee center. Use of a standardized and replicable approach for LE positioning is important for reliable and accurate alignment measurements. Changes in limb rotation, foot position and knee flexion alter the HKA angle.
For example, external rotation has been shown to increase the appearance of varus malalignment.
None of these methods account for the variability between individuals with respect to rotation of the femur and tibia, position of the bony landmarks, fexibility of the feet (for example, pes planus leads to internal rotation of the tibia) and the relative length of the hip musculature (for example, a tight piriformis can lead to excessive external rotation of the hip when in a self-selected stance position).
The LE should be positioned in neutral alignment such that the knee fexion angle is directly in the sagittal plane. This is accomplished by positioning the patient or participant with the heels placed a standard distance apart (for example, 9 cm between the centres of the heels) and adjusting the rotation of the legs until the knee flexion axis, observed as the knee is flexed and extended, lies directly in the frontal plane. Foot position may be recorded from a template marked in degrees of internal and external rotation.
Full-limb radiographs have become increasingly popular for measuring axial alignment. Filters mounted to the x-ray collimator adjust for soft tissue disparity between the hip, knee, and ankle with a single exposure X-ray technicians must be aware that a true anteroposterior radiograph is essential: malrotation, particularly with any degree of knee flexion, will distort the true tibiofemoral angle.
The HKA has 3 angular components: (1) the angle between the articulating surface of the femoral condyles, and the femoral mechanical axis, which is; the condylar-hip or CH angle; (2) the angle between tibial plateau surface and the tibial mechanical axis, which is the plateau-ankle or PA angle); and (3) the angle between the 2 joint surfaces, which is the condylar-plateau or CP angle.
The angles are