Multi-System Factors Associated with Metatarsophalangeal Joint Deformity in Individuals with Type 2 Diabetes

The underlying factors contributing to metatarsophalangeal joint deformity, a known precursor to skin breakdown in individuals with diabetes mellitus (DM), is likely to involve multiple body systems. The purpose of this cross-sectional study was to identify multi-system factors associated with metatarsophalangeal joint deformity in individuals with type 2 DM and peripheral neuropathy (n = 60). Metatarsophalangeal joint deformity was quantified with a computed tomography (CT) scan. System biomarkers included the musculoskeletal system (foot intrinsic muscle deterioration, tarsal/metatarsal bone mineral density, ankle dorsiflexion, metatarsophalangeal extension movement during a sit to stand task); the vascular system (ankle-brachial index); and the endocrine/immune systems (high sensitivity C-reactive protein, skin intrinsic fluorescence, and hemoglobin A1C). Muscle deterioration (r = 0.27), bone density (r = -0.35), metatarsophalangeal extension movement (r = 0.50), maximum dorsiflexion (r = -0.31), and ankle-brachial index (r = 0.33) were related to metatarsophalangeal joint deformity (p < 0.05). Bone mineral density and metatarsophalangeal extension movement were retained in a regression model relating to deformity (R-2 = 0.34). All musculoskeletal system biomarkers and the ankle-brachial index demonstrated weak to moderate relationships to metatarsophalangeal joint deformity. Bone mineral density of the tarsal/metatarsal bones and extending the toes during a sit to stand task were the two strongest factors associated with metatarsophalangeal joint deformity. Evaluation and management of foot bone mineral density and toe extension movement pattern could reduce metatarsophalangeal joint deformity and the risk of skin breakdown and subsequent amputation.