Improving Prevention and Treatment of Foot Ulcers

Foot ulcers are a common complication of diabetes and the most common reason for lower-extremity amputation in the United States. Therefore, understanding the ulcer-producing process is important to detect feet that are at risk. A study conducted at the Washington University School of Medicine, St. Louis, Missouri, identified and quantified soft-tissue and bone structural changes in the forefeet of diabetic patients with a previous history of foot ulceration to serve as a guide in preventing or treating foot ulcers in such patients.

Douglas D. Robertson, MD, PhD, Departments of Radiology and Orthopaedic Surgery of Pittsburgh Medical Center Musculoskeletal Imaging and Biomechanics Laboratory; and Michael J. Mueller, Kirk E. Smith, Paul K. Commean, Thomas Pilgram, PhD, and Jeffrey E. Johnson, MD, Mallinckrodt Institute of Radiology and Department of Orthopaedic Surgery, Washington University School of Medicine, evaluated the forefoot structure of 32 individuals--16 diabetic patients and 16 matched controls--to determine differences between those diabetic individuals with a previous foot ulcer and healthy control subjects. The results are published in the August 2002 Journal of Bone and Joint Surgery (JBJS), Volume 84-A, Number 8.

The purpose of the study was to use computed tomography as a research tool to display a three-dimensional musculoskeletal structure in which internal and external soft tissue, bone structure, and joint disease can be identified and measured. Using computed tomography eliminates the limitations of previously used radiography and ultrasound, which do not allow a unified structural assessment. Computed tomography thus allowed the researchers to explore the relationship between foot structure and function in order to develop better methods of preventing and treating foot disease.

While there are many causes of diabetic ulceration, soft-tissue change is a primary factor. The researchers found that muscle density of the sole of the foot was significantly lower in diabetic individuals. Although overweight individuals in the control group also had less dense muscle tissue, the relationship between muscle density and body weight was not found in individuals with diabetes. Therefore, though obesity causes unhealthy changes in the forefoot, the influence of diabetes is greater.

Bone changes are also key factors in the ulceration process. Changes in the joints of the foot caused by low muscle density alters weight-bearing pressure on the foot. This was more prevalent in those with diabetes, probably because of muscle wasting caused by diabetic neuropathy, the sensory and motor nerve disorder characteristic of diabetes. This finding confirms previous studies in which joint changes, such as hammer toe, were found to be a risk factor of ulceration.

Diabetic individuals also had more joint disease than the controls, especially in the second, third, and fourth toes. The researchers theorized that such diabetic effects as loss of muscle density and hammer toes can increase joint disease.

The purpose of this study was to identify the structural components of the diabetic foot that may lead to ulcer formation. The researchers found computed tomography to be an effective tool to assess variations between the forefeet of diabetic patients and normal matched controls. Evaluating the density of both soft and bony tissue provides information for the development of prevention or treatment therapies for foot ulcers in individuals with diabetes.

The Journal of Bone and Joint Surgery (JBJS) is a publication of the 25,500-member American Academy of Orthopaedic Surgeons (www.aaos.org or http://orthoinfo.aaos.org), a not-for-profit organization that provides education programs for orthopaedic surgeons, allied health professionals, and the public.

The peer-reviewed JBJS, located in Needham, Massachusetts, is published monthly. Abstracts are available online at http://www.jbjs.orgAn orthopaedic surgeon is a medical doctor with extensive training in the diagnosis and nonsurgical as well as surgical treatment of the musculoskeletal system including bones, joints, ligaments, tendons, and nerves.