Diagnosis of osteomyelitis in neuropathic foot ulcers

We reviewed all patients with a clinically infected foot ulcer attending a specialised neuropathic foot clinic. Neuropathy was confirmed by the inability to feel a 5.07 Semmes-Weinstein hair, areflexia and impaired vibration sense, as measured by a biothesiometer. Of 40 patients who attended the clinic over a two-year period, six with ischaemic ulcers were excluded. The remaining 34 had plain radiographs of the foot followed by a 99mTc-MDP bone scan. If the latter was positive, an 111In-labelled WBC scan was performed with planar and/or tomographic dual-isotope studies where appropriate. Bone and WBC scans were performed in 31 patients. In ten, isotope imaging showed infection localised to the soft tissues only and conservative treatment was successful in them all. Eighteen patients were treated surgically with excision of the involved bone, which was sent for culture and histological examination. Dual-isotope scans had a sensitivity of 93% and a specificity of 83%. 99mTc-MDP bone scans with the appropriate In-labelled WBC scans can reliably determine the site and extent of osteomyelitis in the neuropathic diabetic foot.