Background: Non-enzymatic glycosylation of tissues damage the innervation of intrinsic foot muscles leading to diabetic neuropathy (DN), and an imbalance between flexors and extensors of the foot. This might derange the arches of the foot and predispose to foot deformity, prior to foot ulceration, and was investigated.
Objective: To determine the variation in arch index (AI) and subtalar joint (STJ) range of motion in diabetic and non-diabetic conditions with and without neuropathy.
Method: Sixty consenting right-hand dominant subjects, comprising three groups of 20 (10 male and 10 females) subjects each, with diabetes (56.60±7.16 years), DN (50.70±10.36 years) and non-diabetic condition (35.50±18.45 years), respectively, were consecutively recruited at the diabetic Clinic, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria. Stahelis method was used to determine the AI. Goniometric assessment of the STJ motions (dorsiflexion, inversion, eversion, and plantarflexion), was done, and data analysed using Pearson correlation coefficient, ANOVA and Turkey HSD as post-hoc, at P0.05.
Results: There was no significant variation in arch index across the groups (F=0.222, P=0.801), but there was significant reduction in dorsiflexion (F=3.416, P=0.040), plantarflexion (F=7.973, P=0.001), inversion (F=4.174, P=0.002), and eversion(F=4.847, P=0.01) as the diabetic state deteriorated. Left AI was significantly and positively correlated to dorsiflexion (r=0.5006, P=0.0124), plantarflexion (r=0.5752, P=0.004), and inversion (r=0.4035, P=0.0389) in diabetic condition without peripheral neuropathy. Left AI was similarly correlated to inversion (r=−0.5704, P=−0.0042), and eversion (r=0.433, P=0.028) in DN.
Discussion: Limitations in STJ motions increased with diabetic complications, and could adversely influence the absorption of transverse rotation during initial contact in stance. Limited dorsiflexion might translate to increased stress on the plantar that would pull apart the ends of the transverse arch of the foot, thereby increasing the AI. This experience might be more adverse in the less dominant foot considering the observed relationship between the left AI and STJ motions, which should be closely monitored in patients with diabetes.