RADIOGRAPHIC MEASUREMENT OF FEMOROTIBIAL ROTATION IN WEIGHT-BEARING. The influence of flexion and extension in the knee on the extensor mechanism and angles of the lower extremity in a healthy population

Abstract

The reproducibility of the rotation of the femur and the tibia and of the Q-angle was 2--3 degrees (SD) and of the patellar translation about 3 mm (SD). The result from the healthy volunteers will be a useful tool for evaluation of disorders in the knee joint.

Can anatomic alignment measured from a knee radiograph substitute for mechanical alignment from full limb films?

“…On the other hand, the flexed knee may be a position more relevant to knee injury and dynamic loading than the fully extended one. Some have suggested that the ideal measure would be of the mechanical alignment during knee flexion (15). Offsets between knee and long limb films could be affected by the severity of knee pain experienced during acquisition of the x-ray which could affect the comfort of knee flexion.…”

Optimizing Limb Position for Measuring Knee Anatomical Axis Alignment from Standing Knee Radiographs

“…In practice, femorotibial alignment is commonly assessed from short views of the knee (Figure 1, hatched area) from which the anatomic (shaft) axes of the femur and tibia (FS, TS) may be located. The femoral mechanical (FM) axis is not available from these views, but may be approximated since FS and FM have a conservative angular offset from each other (about 4°-5°, with low variance) [15][16][17][18][19][20] . Correlations (r) between the femorotibial angle from knee radiographs and the mechanical axis angle obtained from full-limb radiographs are reported to range from 0.65 to 0.88 17,18,21 .…”

“…For this purpose there is a reference template on the platform 11 ( Figure 3). Images are generally obtained with the knee extended, but Sanfridsson, et al 15 have shown that controlled semiflexed views can be obtained using the frame. In an analysis of HKA and femoral shaft-tibial shaft (FS-TS) angle measurements in healthy volunteers 15 , the authors found differences of less than 1°between the semiflexed and extended positions attributable to femorotibial…”

“…Therefore, recognition of deformities and control of rotation in the context of both health and disease are important goals for reproducible radiography. Certainly, variations of limb position, especially rotation, significantly influence the alignment measures 14,15 . The purpose of our editorial is to discuss practical ways to minimize positional errors.…”

The Biomechanics of the Anterior Cruciate Ligament and Its Reconstruction

“…Blankevoort et al (1988) and La Fortune et al (1992) found no screw-home mechanism during weight bearing in vivo, and suggested that the knee has a range of motion that is specifically dependent upon passive characteristics. For example, the screw-home mechanism can be found to be overcome by external passive forces during movement (Sanfridsson et al, 2001;Smith et al, 2003).…”