Clin Orthop Surg.  2009 Sep;1(3):128-131. 10.4055/cios.2009.1.3.128.

Bony Landmarks for Determining the Mechanical Axis of the Femur in the Sagittal Plane during Total Knee Arthroplasty

• Seo JG
• Kim BK
• Moon YW
• Kim JH
• Yoon BH
• Ahn TK
• Lee DH

• KMID: 999390
• DOI: http://doi.org/10.4055/cios.2009.1.3.128

Abstract

BACKGROUND
There is no accepted landmark for the mechanical axis of the femoral axis in sagittal plane in conventional total knee arthroplasty. METHODS: As palpable anatomic landmarks of the femur, lateral epicondyle, and anterior margin of the greater trochanter were identified. The line connecting these two landmarks was defined as the "palpable sagittal axis". The mechanical axis of the femur was compared with the palpable sagittal axis and the distal femoral anterior cortex axis. These axes were also compared with sagittal bowing of the femur. RESULTS: The distal femoral anterior cortex axis and the palpable sagittal axis were flexed by 4.1degrees and 2.4degrees more than the sagittal mechanical axes, respectively (p < 0.05). However, the palpable sagittal axis was not correlated with sagittal bowing of the femur (Spearman's rs, 0.17; p = 0.14). CONCLUSIONS: The palpable sagittal axis showed a consistent relationship with the sagittal mechanical femoral axes regardless of the severity of the sagittal bowing of the femur.

Keyword

Bony landmark; Sagittal alignment; Mechanical axis; Total knee arthroplasty

MeSH Terms

Aged
Aged, 80 and over
Arthroplasty, Replacement, Knee/*methods
Biomechanics
Female
Femur/anatomy & histology/*surgery
Humans
Knee Joint/anatomy & histology/surgery
Male
Middle Aged

Figure

• 

  Fig. 1 (A) Lateral epicondyle of the femur was marked with an electrocardiogram lead (arrow). (B) Two kinds of palpable anatomical landmarks - anterior margin (a) of the greater trochanter (arrow) and lateral epicondyle of the femur (a') - were identified and the line aa' was defined as the "palpable mechanical axis" of the femur in the sagittal plane.

• 

  Fig. 2 (A) The mechanical axis of the femur in the sagittal plane was defined as the line connecting the center of the femoral head (a) and the center of the condyles (a'). The line connecting anterior margin of the greater trochanter (b) and the center of the lateral epicondyle of the femur (b') was defi ned as the "palpable mechanical axis." The axis of the anterior cortex of the distal femur (c) was defined as a line along the cortex just above the femoral condyles. (B) Sagittal bowing of the distal femur as the angle (α) between the longitudinal axis of the proximal and distal femur. The proximal axis was obtained connecting the centers of the medullary canal at the level of the lesser trochanter (a) and the point (a') 4 cm distal to the lesser trochanter. The distal axis was obtained connecting the centers of the medullary canal at the junction (b) between the femoral shaft and the condylar region and the point (b') 4 cm proximal to it.

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