The role of limited joint mobility in diabetic patients with an at-risk foot.

OBJECTIVE To assess the role of limited joint mobility (LJM) in causing abnormal high plantar pressures in the forefoot of diabetic patients with an at-risk foot. RESEARCH DESIGN AND METHODS A total of 70 type 1 or type 2 diabetic patients and 30 control subjects participated in this cross-sectional study. Thirty-five diabetic patients with an at-risk foot, defined as a foot with neuropathy but without ulceration or previous ulceration, and 35 diabetic control subjects without neuropathy were selected for the subgroups. Joint mobility was assessed in the foot at the ankle and metatarsophalangeal I (first MTP) joints. Using the FastScan plantar pressure analyzer, the pressure-time integrals (PTIs) as dynamic variables were measured in each foot. The clinical assessment included standard measures of peripheral neuropathy. RESULTS The mobility at the ankle and first MTP joint were significantly reduced in the foot-at-risk group compared with the diabetic control group and the control subjects (P < 0.0001). The PTIs were significantly higher in the foot-at-risk group compared with the two other groups (P < 0.0001). There was a strong inverse correlation between the mobility of the ankle or first MTP joint and the PTI of the diabetic patients (r = -0.67, P < 0.0001, and r = -0.71, P < 0.0001, respectively). The vibration perception threshold was positively correlated with the PTI of the diabetic patients (r = 0.44, P = 0.0001). CONCLUSIONS Diabetic patients with an at-risk foot have reduced joint mobility and elevated PTIs on the plantar forefoot, placing them at risk for subsequent ulceration. Therefore, LJM may be a possible factor in causing high plantar pressures and may contribute to foot ulceration in the susceptible neuropathic at-risk foot.