Tests for Diagnosing Chronic Osteomyelitis in the Diabetic Foot. Part 3

All of the patients with diabetic ulcers underwent plain radiography to obtain dorsoplantar, lateral, and oblique views of both feet for assessment of possible bone alterations produced by the lesion. Osteomyelitis was suspected when one or more of the following radiographic signs were observed: periosteal elevation, cortical disruption, medullary involvement, osteolysis, and sequestra (segments of necrotic bone separated from living bone by granulation tissue).

Finally, based on the results of the clinical examination, soft tissue culture, PTB, and plain X-ray, patients with a diagnostic suspicion of osteomyelitis were subjected to a bone tissue biopsy obtained by conservative surgery. During surgery, we first removed all nonviable infected soft tissue and then excised all of the affected bone, obtaining a representative bone sample for subsequent histopathological analysis. The bone biopsy specimens were introduced in a sterile recipient containing 10% buffered formalin solution and transported to the pathological anatomy laboratory within 48 h, where they were immediately processed and examined. The histological criteria considered diagnostic of osteomyelitis were inflammatory cell infiltrate mostly composed of lymphocyte cells, plasma cells, neutrophils within spongy and cortical bone; bone necrosis; and reactive bone neoformation possibly accompanied by prominent periosteal bone proliferation (18). We used the results of the bone biopsy to confirm the diagnosis of osteomyelitis.

The prevalence of osteomyelitis in the 132 patients with clinical suspicion of infection included in this study was 79.5% (105 patients). Each of these patients had a single ulcer. Of the ulcers, 59% were classified as neuropathic and 41% were classified as neuroischemic. The mean ± SD duration of diabetes was 15.6 ± 9.5 years, blood glucose was 161.4 ± 60.3 mg/dl, and A1C was 7.9 ± 1.9%. The following complications of diabetes were recorded: diabetic retinopathy in 68 patients (51.5%), diabetic nephropathy in 27 patients (20.5%), hypertension in 94 patients (71.2%), stroke in 62 patients (47%), cardiovascular problems in 56 patients (42.4%), prior ulcers in 65 patients (49.2%), and prior conservative lower extremity amputation in 48 patients (36.4%).

The etiopathogenic characteristics of the ulcers were lack of pedal pulses in 33 patients (25%), a positive monofilament test in 100 patients (75.8%), and vibration sensitivity in 121 patients (91.7%); the ankle-arm index was 0.91 ± 0.3 and TcPo2 was 34.2 ± 14 mmHg. In 124 patients (93.9%), the ulcer was classified as Wagner grade III, in 5.3% as grade II, and in 0.8% as grade IV. According to Texas classification, the ulcers in 73 patients (55.3%) were type IIIA and in 41 patients (31.1%) they were type IIIB; types IA and IIIC were less frequently recorded, and each appeared in only 1 patient (0.8%).

In 75 patients (56.8%), the exudate from the ulcer was serous, in 32 patients (24.2%), there was no exudate, in 18 patients (13.6%), the exudate was purulent, in 5 patients (3.8%), it was sanguinous, and in 2 patients (1.5%) it was serosanguinous. In 98.2% of the patients, the ulcers appeared on the forefoot. Most of these ulcers appeared on the middle toes (second, third, and fourth) (28.7%) or the underside of the second, third, and fourth metatarsals (27.2%). The least frequent locations were over the scaphoid (0.9%) and cuboid (0.9%) bones.