Cadaveric study (n=15) testing whether knee kinematics during simulated weight-bearing squatting reduce to rotations about two fixed bony axes. The primary question: does the palpable transepicondylar axis reliably identify the true flexion axis of the knee? Simulated squatting with quadriceps loads up to 1000 N was used to replicate physiologic loading conditions.
Setting femoral component rotation in TKA requires a reliable intraoperative landmark, and for years surgeons debated which reference was most accurate. This paper answers that question directly: the transepicondylar axis deviates from the biomechanically optimal flexion axis by only 0.2 mm, with no statistically significant difference.
When you palpate the medial and lateral epicondyles and mark your rotational reference, you are working within the margin of error of the true flexion axis. That alignment targets a balanced flexion gap and symmetric collateral tension from 5° to 90° — the functional arc that matters for most daily activities.
The transepicondylar axis has a specific advantage in arthritic knees: unlike the posterior condylar line or articular surface geometry, it is defined by bony prominences unaffected by cartilage wear or asymmetric condylar erosion. For any case with significant medial or lateral bone loss where the posterior condylar offset is unreliable, the transepicondylar axis is the reference of choice.
Cadaveric study (n=15) testing whether knee kinematics during simulated weight-bearing squatting reduce to rotations about two fixed bony axes. The primary question: does the palpable transepicondylar axis reliably identify the true flexion axis of the knee? Simulated squatting with quadriceps loads up to 1000 N was used to replicate physiologic loading conditions.
Setting femoral component rotation in TKA requires a reliable intraoperative landmark, and for years surgeons debated which reference was most accurate. This paper answers that question directly: the transepicondylar axis deviates from the biomechanically optimal flexion axis by only 0.2 mm, with no statistically significant difference.
When you palpate the medial and lateral epicondyles and mark your rotational reference, you are working within the margin of error of the true flexion axis. That alignment targets a balanced flexion gap and symmetric collateral tension from 5° to 90° — the functional arc that matters for most daily activities.
The transepicondylar axis has a specific advantage in arthritic knees: unlike the posterior condylar line or articular surface geometry, it is defined by bony prominences unaffected by cartilage wear or asymmetric condylar erosion. For any case with significant medial or lateral bone loss where the posterior condylar offset is unreliable, the transepicondylar axis is the reference of choice.