By Dr. Christopher Brigham

This week's tip is courtesy of Ken Subin, MD, MPH who joined our staff on a full-time basis this month. (Dr. Subin is a highly qualified occupational medicine physician who has a superb understanding of the AMA Guides.)

The evaluation for ankle motion impairment is not a complex process, but there are several components to the exam where errors are frequently committed.

Here are tips to help you complete your ankle impairment assessment correctly as instructed in Chapter 17 of the Guides:

* Figure 17-5 on page 535 explains that ankle plantar flexion and dorsiflexion (extension) measurements are to be obtained both with the knee in full extension and flexed to 45 degrees. The average of the measurements obtained for each plane of motion in the two knee positions represents the actual value to be used for the impairment rating. Apply these values to Table 17-11 on page 537 to determine impairment. Note Figure 17-5 uses the term "Dorsiflexion" and Table 17-11 uses the term "Extension"; they are the same. (Plantar flexion is referenced correctly.)

* When assessing impairment for ankylosis of the ankle joint, do not forget there is a baseline 4% whole person impairment (10% lower extremity, 14% foot) for ankylosis in a neutral position. Any variation from the neutral position as indicated in Tables 17-24 to 17-28 on page 541 will be additional impairment to this 4% whole person. For example, an ankle fused in 7 degrees of varus will result in a final 14% whole person impairment. Remember, these tables are used for determining impairment of ankylosed joints only. For range of motion measurements, use Tables 17-11, 12, and 13 on page 537.

* If you have impairments of both the Ankle and the Hindfoot "combine these regional, lower extremity impairments of the foot and convert the combined foot impairment to a whole person" as explained on page 528. (There is a convenient conversion tool at www.impairment.com/tools.)

Brigham is the editor of the Guides Newsletter and Guides Casebook. To view more of these tips visit:

www.impairment.com/tips

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