“Silent” bone stress injuries in the feet of diabetic patients with polyneuropathy: a report on 12 cases

Abstract

Bone stress injuries are rarely being diagnosed in patients with sensory neuropathy, most likely because they may be silent in terms of pain. Load-related pain is considered a key feature of any bone stress injury, a symptom, which may be partially or completely absent in subjects with sensory neuropathy (loss of protective sensation). We evaluated the clinical course of bone stress injuries in insensitive feet in diabetic patients with polyneuropathy. We investigated 12 consecutive diabetic patients with bone stress injuries of the foot (bone marrow edema, bone bruise and microtrabecular fractures, on magnetic resonance imaging MRI), which were undetectable on plain X-ray. All patients suffered from diabetic polyneuropathy, none of them had an active foot ulcer. The patients presented with a swollen foot, which was only mildly painful and did not prevent them from walking. Complaints were related to the swelling, which increased during load-bearing. In seven cases, a traumatic event preceding the onset of symptoms could be ascertained. MRI disclosed stress injuries in 2.5 (1-8) [median (range)] bones per foot. In 11 patients, treatment was started immediately by off-loading with total contact cast for 17 (8-52) weeks, followed by gradual increase in weight bearing. One patient unfortunately received off-loading treatment only after deforming fractures had developed. All bone injuries healed uneventuelly in eight patients, and with residual mild osteoarthrosis in three patients without gross deformities. However, the untreated patient developed severe Charcot foot deformity. In diabetic patients with polyneuropathy, symptoms of bone stress injuries of the foot are atypical, in that there is load-related swelling rather than load-related pain. Immediate diagnosis, and treatment with off-loading, leads to a restitutio ad integrum like in non-neuropathic patients. Delayed cessation of overuse, however, may cause irreversible joint and bone damage (Charcot foot).