Abstract
Aim: The aim of this research was to assess the difference in the observed tibiofemoral axis between long leg and short AP films of the knee.
Method: 20 patients who were undergoing primary total knee replacement, and had had no previous surgery on the affected limb were x-rayed using the a long leg cassette to include both the hip and ankle joints. A special screen was constructed to obscure all the x-ray except for a field, the size of a standard AP x-ray of the knee. The tibiofemoral angle was measured by two independent observers first on the short film and then on the long leg film.
Results: Our results have shown that the short leg film consistently overestimates the true tibiofemoral angle. Intraobserver correlation is also better when comparing the long leg film rather than the short film.
Conclusion: Measurement of the tibiofemoral or anatomical axis of the knee is best performed using long leg films, as this appears to give more consistent and reproducible results.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
