The relationship of anteroposterior, transepicondylar and posterior condylar axis of the femur: a Thai cadaveric study using digital measurement.

Objective: To study the normal relationship of the anteroposterior (AP), transepicondylar (TE) and posterior condylar (PC) axis of cadaveric femoral bones using digital technology and special computer program.

Material And Method: Digital image of distal femur of 100 cadaveric bones of both sides and both sexes were taken using a special stand and clamp to ensure the same view and same distance from bone to camera. All still images were transferred into a specially developed computer program, then reference points were located by two observers, and were done twice at one week interval. The program reported the angle between AP-TE, AP-PC and TE-PC axes automatically. The data was then analyzed.

Results: The age of donor cadaveric bones ranged from 22 to 58 years (average 45.61 +/- 7.73). The AP-TE, AP-PC and TE-PC angles were 92.43 +/- 2.07, 86.65 +/- 1.85 and 5.79 +/- 1.26, respectively. The correlation coefficients of intra-observer reliability in observer 1 were 0.89, 0.87 and 0.91; in observer 2 were 0.92, 0.90 and 0.87. The correlation coefficients of inter-observer reliability were 0.81, 0.82 and 0.80. Limit agreement tests of AP-TE, AP-PC and TE-PC were 90.59%, 92. 57% and 96.03%, in that order.

Conclusion: Using digital technology, the normal relationship of AP, TE and PC axes of femur from cadaveric bone could be more accurately studied comparing with the previous studies performing measurement on plain film, CT scan or MRI using goniometer.