ADA 2008: Pedal osteolysis can be biomarker for diabetic disease

Current research suggests that pedal osteolysis, the loss of bone mineral density (BMD) in the foot, may be a useful biomarker for Charcot's arthropathy and other diabetic foot diseases.

"Pedal osteolysis is probably involved," said David Sinacore, PT, PhD, Washington University School of Medicine, St. Louis, and winner of the 2008 Roger Pecoraro Award. "Bone loss may be a pathogen in at least some cases."

The confounder, Dr. Sinacore explained, is that pedal osteolysis is also a normal feature of aging. Bones in the feet typically lose BMD beginning as early as the 20s. Population studies suggest that the typical woman loses about 40% of BMD in the foot by her 60s, the typical male 36%. That leaves clinicians trying to distinguish normal BMD loss from pathenogenic loss.

Diabetic foot disease triad
Diabetic foot disease typically involves a triad of minor trauma, ulceration and failure to heal. But while these three conditions are typical, he continued, they are rarely sufficient to trigger problems alone. Other factors are involved.

Bone loss may be one of those factors. BMD loss of 10 to 15% is commonly observed in both type 1 and type 2 diabetes, Dr. Sinacore noted. Bone loss may trigger a cascade of events that can result in disease, deformity and amputation.

Neuropathic midfoot deformities are the single greatest contributor to ulceration and subsequent associated problems. Charcot's foot, a complete collapse of the arch, is one of the most virulent impairments seen in diabetic patients. Dr. Sinacore has documented BMD loss up to 50% in as little as 2 months in Charcot patients.

The problem typically begins with a minor fracture or other acute insult that is not noticed by the patient. As damage spreads, the foot becomes inflamed and swollen. In Charcot's arthropathy, the midfoot falls below the weight-bearing surface of the foot where it is subject to repeated insult and injury, leading to ulceration.

Skin temperature may be another early indicator of developing problems. In data published earlier this year, Dr. Sinacore found that patients with Charcot's arthropathy had an 8.4-degree (F) difference in skin temperature between the Charcot foot and the uninvolved foot. The involved foot was not only hotter, it had lost 37% in BMD while the uninvolved foot had lost 22% in BMD.

"Inflammation is associated with bone loss," Dr. Sinacore said. "BMD loss is fairly acute. Inflammation is probably a key indicator. The intensity of that inflammation and the duration are probably the key elements."