Patient bone evaluation (BE) can be a sensitive method for the determination if therapy is needed to restore bone strength. Until the present, a Bone Density test has been necessary to make such a determination. This test can be expensive and somewhat intrusive. On the other hand, a bone evaluation test can be made utilizing the raw data contained within a standard AP view of the foot.
Classic bone densitometry compares the absorption properties of the vertebra of the lumbar spine with soft tissue surrounding the spine. On occasion, a similar measurement is made in the human wrist where the radius and ulna bone absorption is compared to soft tissue surrounding the wrist. This is normally performed while the wrist is immersed in water. Immersion in water is used to adjust for fat content that may surround the wrist and bias the soft tissue contribution.
The standard AP view of the foot produces an image of the foot while the body is stressed by the weight of the entire body. The foot is as flat as possible which results in any fat contained within to be spread over the entire area of the foot. The resultant image shows data that is located in the web of the big toe that is adjacent to the bone of the big toe.
The bone evaluation (BE) calculation is made by a simple ratio of bone absorption vrs soft tissue absorption. This measurement is relative with the first test but absolute when the second test is administered. A sample area of approximately 60 by 180 pixels is used in order to avoid great variations in sample area. It is recommended that several measurements be made to avoid positional area variations. As in all cases of bone densitometry, position variances can influence test results and this has been especially true with wrist measurements.
This is much less so in the case when dealing with the AP view of the foot. A record is made within the patient chart for each measurement made. This allows for variations over time.