Role of Intrinsic Muscle Atrophy in the Etiology of Claw Toe Deformity in Diabetic Neuropathy May Not Be as Straightforward as Widely Believed
Role of Intrinsic Muscle Atrophy in the Etiology of Claw Toe Deformity in Diabetic Neuropathy May Not Be as Straightforward
as Widely Believed
Previous SectionNext Section
RESEARCH DESIGN AND METHODSTwenty diabetic patients with distal symmetric polyneuropathy participated in this cross-sectional study. Ten of these patients(five men and five women) had claw toe deformity involving hyperextension of the MTP joint (experimental group). The other10 patients were matched on age (?5 years) and sex and had normally aligned toes (control group). Five age-matched healthysubjects (three men and two women) with normally aligned toes were included for reference purposes in MRI assessments. Thepresence of toe deformity was initially assessed clinically for recruitment purposes but eventually based on MRI analysisas described below. One lower extremity per subject was examined because of the limited time available per patient on theMRI scanner. This was the extremity with toe deformity if the toes of the contralateral foot were not deformed or was randomlyassigned if not excluded by the criteria mentioned below.
Distal symmetric polyneuropathy was assessed clinically and confirmed to be present in all patients by abnormal vibrationperception thresholds measured at the dorsal surface of the hallux in both feet using a Biothesiometer (Bio-Medical InstrumentCompany, Newbury, OH) (16), and the inability to sense the pressure of a 10-g (5.07) Semmes-Weinstein monofilament at, at least, one of eight sitestested (six plantar foot regions, dorsum of the foot, and medial malleolus). Written informed consent was obtained from eachsubject before the start of the study, which was approved by the local medical ethics committee. Patient characteristics aresummarized in Table 1.
View this table:In this windowIn a new windowTable 1Baseline patient characteristics and study results
Maximal effort was made to exclude congenital or external causes of claw toe deformity in the experimental group. For thispurpose, the patients' shoes were examined, and patients were asked about the onset of their deformity and the fitting oftheir shoes in the past. Patients were excluded if their shoes were found to be too small in size for their feet, if theyreported having worn ill-fitting shoes in the past, or if toe deformity was present before the onset of diabetes. For thesame reason, patients with neuromuscular diseases or neurological problems other than diabetic polyneuropathy were excluded.Other exclusion criteria were 1) age 65 years; 2) peripheral vascular disease, as determined by absent pedal pulses with an ankle-brachial index