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

Constitutional Varus Does Not Affect Joint Line Orientation in the Coronal Plane

“…In recent publications we reported detailed values on the distribution and means of knee alignment in the coronal and horizontal planes, diverging from previous assumptions that ruled for a long time [12,28]. However, a systematic understanding of the role of joint line orientation and its association with the development of malalignment and arthritis is lacking.…”

“…We selected the method described by Paley et al [24] because radiology technicians were well trained and had long-standing experience with the patellar orientation method. However, aligning the lower limb with the patella facing forward is a potential risk for rotational errors when there is patellar malalignment [12] but because we excluded patients with fixed flexion deformity, the risk of misinterpreting the HKA angle was minimized.…”

“…However, a systematic understanding of the role of joint line orientation and its association with the development of malalignment and arthritis is lacking. Several studies looked at joint line orientation in association with coronal malalignment [2, 7-9, 12, 22-24], but joint line orientation was mostly described in relation to the femoral and tibial mechanical axis [7,12,13,23]. We took a different approach and looked at the orientation of the joint line relative to the floor in bipedal stance.…”

“…Within the description of coronal alignment, joint line orientation plays an important role [7][8][9][10][11][12][22][23][24]. Varus alignment of the articular surface of the proximal tibia has been reported to be present in 88% of patients with medial compartment osteoarthritis [9].…”

The Chitranjan Ranawat Award: Is Neutral Mechanical Alignment Normal for All Patients?: The Concept of Constitutional Varus

“…The second limitation to our study is the use of full-leg standing radiographs for our measurements. Although this method is well validated in the literature and has excellent intra-and interobserver reliability, the rotational position of the lower extremities might influence the outcome of the measurements [8,12,13,21,27,38]. The rotational position of the knee compared to the hip and ankle is variable, and a perceived constitutional varus could therefore in fact be an external rotation of one subject's limb as compared to another.…”