Chang et al., show, with some elegant illustrations, some important limitations in estimating the Mechanical Axis (MA) of osteoarthritis (OA) knees using anatomical shaft data. Our observations are closely aligned. Chang et al. suggest that the tibial femoral angle (TFA) calculated using the points bisecting the long bones 15 cm (TFA2) rather than 10 cm (TFA1) from the knee joint does a better job as a reference for MA. We agree with the proviso that limitations are still evident when using the marginally revealed anatomy of a 17-inch cassette, better in women (smaller frames) than men. The smaller stature of Koreans may favor their findings. Suffice to say, that the greater amount of shaft defined on the film the better, and the best is full length.
展开▼
