<i>In vivo</i> relationship between the clinical epicondylar axis and the anterior pelvic plane in normal subjects

Abstract

Background: Several researchers consider the clinical epicondylar axis (CEA) as the functional flexion-extension axis of the knee. The anterior pelvic plane (APP) is commonly used as an anatomical reference plane of the pelvis. However, no study has investigated the relationship of the APP with the CEA and PCA. In this study, we aimed to investigate the relationship of the APP with the CEA and posterior condylar axis (PCA) in the standing and supine positions. Methods: We recruited 77 healthy Japanese subjects for this study, and carried out measurements using the Hip CAS ® system, a 3D system used for the assessment of lower extremity alignment. Results: The mean femoral neck anteversion was 16.33˚. There was an approximate discrepancy of 6˚ between the male and the female in anatomy (15.73˚ and 21.15˚ in the male and female subjects, respectively). The mean condylar twist angle (CTA) was 6.86˚ and the mean APP-PCA value in the standing position was −6.88˚. The mean APP-CEA value in the standing position was 0.02˚, and the discrepancy between males and females was only 0.21˚ (0.09˚ and −0.13˚ for the male and female subjects, respectively). This meant that Xp axis of APP and CEA were almost parallel. On the other hand, the mean APP-CEA value in the supine position was 7.07˚ (male subjects = 9.48˚; female subjects = 5.62˚). Here, the CEA was approximately parallel to the horizontal axis of the APP, which was compatible with the neutral position of the knee and hip joint, and anatomically and kinesiologically justified in normal subjects. Conclusion: CEA was approximately parallel to the horizontal axis of the APP. These results are compatible with regard to the neutral position of the knee and hip joints, and anatomically and kinesiologically justified in normal subjects. Moreover, CEA is a potential reference axis for the insertion of the femoral component in THA.

The anteroposterior axis of the tibia is approximately perpendicular to the anterior pelvic plane in the standing position in healthy Japanese subjects

“…We previously described that CEA was approximately parallel to the transverse axis of the APP plane in the standing position in normal subjects [ 14 ] and in our current study, we reported that the KRA was almost 0° and that the tibia AP axis was approximately perpendicular to the CEA. This new concept in the current study may be important to integrate these two axes with regard to not only the anatomical reference, but also the kinesiology of the lower extremity including the pelvis, hip joint, and knee joint.…”

“…We previously reported that the CEA runs approximately parallel to the transverse axis of the anterior pelvic plane (APP) in the standing position in healthy subjects [ 14 ]. However, to our knowledge, no report has described the rotational alignment between APP and AP axis of the tibia, and if they are perpendicular to CEA in the standing position.…”

Sex differences in femoral deformity determined using three-dimensional assessment for osteoarthritic knees

“…In other words, the foot and the extensor mechanism, such as the quadriceps femoris, must be maintained in the forward direction during walking. Imai et al [9] demonstrated that the anterior pelvic plane is parallel to the transepicondylar axis approximating the functional flexion axis of the knee in the standing position, which indicates that humans move with coinciding motion planes of the pelvis and knee joint. The vastus medialis, vastus lateralis, and vastus intermedius in the quadriceps femoris attach from the anterolateral aspect to the posterior linea aspera in the proximal femur [2].…”

The anteroposterior axis of the tibia is adjusted to approximately a right angle to the anterior pelvic plane in the standing position in patients with hip dysplasia similar to normal subjects: a cross-sectional study

“…We previously found that the CEA and the transverse axis of the anterior pelvic plane (APP) are approximately parallel in the standing position in healthy subjects [ 14 ]. Moreover, we also described that the AP axis of the tibia is approximately perpendicular to the transverse axis of the APP in the standing position in healthy subjects [ 15 ].…”