Are We Misdiagnosing Diabetic Foot Osteomyelitis?

Rationale and Aim: To compare the incidence of osteomyelitis based on different operational definitions using the gold standard of bone biopsy.

Methods: We prospectively enrolled 35 consecutive patients who met the criteria of ?21 years of age, a moderately or severely infection based on the Infectious Diseases Society of America. Bone samples were obtained from all participating patients either by percutaneous bone biopsy or intraoperative if the patient required surgery in the operating room. Bone samples were analyzed for conventional culture, histology examination, and16S rRNA qPCR. We evaluated five definitions for osteomyelitis: 1. traditional culture 2. traditional histology 3. genetic sequencing 4. traditional culture and histology 5 genetic sequencing and histology.

Results: There was significant variability in the incidence of osteomyelitis based on the criteria for diagnosis. Traditional cultures identified significantly more cases of osteomyelitis than histology alone (68.6% vs. 45.7%, p=0.02). In every case that histology reported osteomyelitis; the bone culture was positive using traditional culture methods and genetic sequencing. 16S rRNA testing identified more cases of osteomyelitis compared to histology (82.9% vs. 45.7%, p=0.001) and compared to traditional cultures (82.9% vs. 68.6%, p=0.31). When both histology and traditional culture (68.6%) or histology and genetic sequencing based cultures (82.9%) were used to define osteomyelitis the incidence of osteomyelitis did not change.

Conclusions: There is considerable variability in the incidence of osteomyelitis based on how the gold standard of bone biopsy is defined in diabetic foot infections.