Factors associated with bone regrowth following diabetes-related partial amputation of the foot

The formation of hypertrophic bone after partial resection of metatarsal bone has the potential to cause abnormal foci of high pressure in people who have diabetes mellitus; this may increase the risk of reulceration and reamputation. However, we are not aware of previous studies evaluating the risk factors for this entity.

The records of ninety-two adults (mean age, 54+/-10.1 years; range, thirty to seventy-four years) with diabetes who had had an isolated partial amputation of a ray were abstracted. Repeat radiographs were made for all of these subjects at a mean of 22+/-6.1 months (range, thirteen to thirty-five months) after the initial procedure. The formation of hypertrophic bone was defined as more than three millimeters of regrowth.

A total of forty-one (45 percent) of the subjects had formation of hypertrophic bone at the time of radiographic analysis after isolated partial amputation of a ray. On multivariate analysis, the factors that were significantly associated with this regrowth of bone were male gender (88 percent [thirty-six] of the forty-one patients who had bone regrowth were male compared with 51 percent [twenty-six] of the fifty-one patients who did not have bone regrowth; p<0.01, odds ratio = 5.7, 95 percent confidence interval = 1.8 to 18.9), the use of manual bone-cutting instruments (used in 56 percent [twenty-three] of the forty-one patients who had bone regrowth compared with 16 percent [eight] of the fifty-one who did not; p<0.01, odds ratio = 4.7, 95 percent confidence interval = 1.6 to 13.8), and a resection made distal to the surgical neck of the metatarsal (used in 34 percent [fourteen] of the forty-one patients who had bone regrowth compared with 12 percent [six] of the fifty-one who did not; p<0.03, odds ratio = 4.5, 95 percent confidence interval = 1.2 to 16.9). The patients who had regrowth of bone were approximately eight times more likely to have reulceration at the site of the amputation than were those who did not have regrowth (24 percent [ten] of the patients with regrowth had reulceration compared with 4 percent [two] of the patients without regrowth; p<0.01, chi square = 8.4, odds ratio = 7.9, 95 percent confidence interval = 1.6 to 38.5).

Overgrowth of the bone of a transected metatarsal predisposes patients to ulceration. Male gender, the use of manual bone-cutting instruments, and metaphyseal amputation may be associated with long-term regrowth of bone following isolated partial amputation of a ray. The use of power instruments during these procedures may lead to a lower prevalence of this reaction, thereby potentially reducing the risk of ulceration, infection, and reamputation.