Reproducibility of foot structure measurements in neuropathic diabetic patients using magnetic resonance imaging

Abstract

Purpose:To assess the intra-and interobserver agreement of commonly reported foot structure measurements in diabetic patients with neuropathy using magnetic resonance imaging (MRI). Materials and Methods:In 23 neuropathic diabetic patients and five age-matched healthy controls, sagittal-plane MR images of the forefoot were obtained to assess joint configuration and plantar fat-pad thickness on two different occasions by the same observer and once by a different observer. The degree of intrinsic muscle atrophy was scored from coronal plane images on two different occasions by two observers. Results:The intraclass correlation coefficients (ICCs) between occasions and between observers were Ͼ0.94. The mean differences (bias) and the limits of agreement (LoA ϭ mean Ϯ 2 SDs) were small for the metatarsal-phalangeal (MTP) joint angle, toe angle, and plantar fat-pad thickness (bias Յ 0.8°or 0.2 mm, LoA Յ 3.8°or 0.8 mm), but larger for interphalangeal joint angles (bias Յ 3.4°, LoA Յ 8.8°). The weighted kappa for intrinsic muscle atrophy was 0.94. Conclusion:Static foot structure data can be assessed reliably using MRI. Because changes in foot structure contribute to the development of foot ulcers in neuropathic patients, MRI may be a useful technique to assess risk of ulceration in these patients. DIABETIC FOOT ULCERATION is a frequently reported and serious complication in people with diabetes and peripheral neuropathy, and precedes the vast majority (85%) of lower-extremity amputations (1). Elevated dynamic plantar pressure has been established as a major risk factor for plantar ulceration in the diabetic foot with lack of protective sensation (2).Structural changes and deformities of the foot, such as claw/hammer toe deformity and thinning of soft tissue or fat pads underneath the metatarsal heads, are associated with increased plantar pressures in diabetic subjects (3-6). Additionally, intrinsic muscle atrophy secondary to peripheral neuropathy may significantly affect foot function and lead to altered gait biomechanics (7).Because of its multiplanar imaging capability and inherent superiority in tissue contrast, magnetic resonance imaging (MRI) is increasingly being used as a tool to assess structural pathology in the foot or lower leg of diabetic patients with peripheral neuropathy (5,7-11). These assessments are considered important for improving our understanding of the relationship between structure and function in the foot and the pathogenesis of foot ulceration.However, little is known about the reproducibility of the MRI assessments for this purpose. Therefore, the purpose of this study was to evaluate the intra-and interobserver agreement of (semi-)quantitative measurements by MRI of foot structure in neuropathic diabetic patients. MATERIALS AND METHODS SubjectsTwenty-eight subjects participated in this study and underwent MRI of the foot. The study group consisted of 23 diabetic patients with peripheral sensory neuropathy (15 men and eight women, mean age ϭ 56.8 years) and five age-matched healthy subject...

Importance and challenges of measuring intrinsic foot muscle strength

“…Indirect methods can assess muscle morphology [6,21-24,55-57], activation patterns [3,12,41] and histochemical properties [13] of intrinsic foot muscles. However, indirect methods are unable to directly measure intrinsic muscle strength.…”

“…Indirect methods are generally used to estimate muscle structure (physiological cross sectional area and volume) [6,21-24,55-57], activity (EMG) [3] and histochemical properties [13]. Indirect methods can discriminate between intrinsic and extrinsic muscles, but are unable to directly determine force or strength.…”

“…Qualitative assessment of MR images in 60 participants with CMT has revealed some degree of fatty infiltration and intrinsic muscle atrophy in all participants [6]. Bus et al [21] has also visualised intrinsic muscle atrophy in patients with Diabetes Mellitus, using a five point scale where 0 indicates healthy tissue with no atrophy and 4 indicates a foot with almost no muscle tissue visible. This method has been shown to have good reliability (Kappa = 0.94) (Table  9).…”

Role of Intrinsic Muscle Atrophy in the Etiology of Claw Toe Deformity in Diabetic Neuropathy May Not Be as Straightforward as Widely Believed

“…For this purpose, we used a semiquantitative 5-point atrophy scale with 0 representing healthy muscle tissue (no atrophy), 1 representing mild atrophy, 2 representing moderate atrophy, 3 representing severe atrophy, and 4 representing almost complete or complete loss of muscle tissue. Reliability in assessing atrophy using this 5-point scale was high, with weighted κ of 0.94 (18). …”

Daily exposure to inhomogeneous static magnetic field significantly reduces blood glucose level in diabetic mice

“…If MRI (Magnetic Resonance Imaging) is used for diagnostic goals in diabetic patients (Bus et al 2006, Larroque et al 2006, its static magnetic field (SMF) component may have an unexpected physiological effect as suggested by László and Gyires (2008). Electromagnetic fields were shown to induce an effect, which was analgesia (Weintraub 2004), vulnerability of diabetic rats (Ö ztaş et al 2004), decrease of neurological deficit and required insulin daily dose, nerve conduction velocity increase, increase of the muscle compound action potentials (muscle power) and peripheral outflow (Chebotar'ova and Chebotar'ov 2003).…”