From the 2019 HVPAA National Conference
Prof. Jan Fritz (The Johns Hopkins University School of Medicine), Prof. Laura Fayad (Johns Hopkins Department of Radiology)
Background
Upon the diagnosis of osteomyelitis, bone biopsy sampling is frequently requested with the intention to identify causative organisms and narrow broad-spectrum antibiotic therapy. Bone biopsy is invasive and associated with considerable cost, whereas the diagnostic yield may be low in chronic osteomyelitis.
Objective
To determine the frequency of CT-guided bone biopsy resulting in the identification of a causative pathogen and tailoring of antibiotic treatment in patients with chronic non-spinal osteomyelitis.
Methods
Following internal review board approval, we identified 181 patients (mean age, 52 years; age range, 20-93 years) with chronic osteomyelitis, who underwent successful non-spinal CT-guided bone biopsy and subsequent microbiological examination. Biopsies were performed in the foot (65/181, 36%), pelvis (75/181, 41%), and other locations (41/181, 23%). The outcome variables included a) diagnostic yield, defined as the identification of a pathogen through microbiological analysis, b) resulting changes of antibiotic treatment, and c) microbiological results from wound cultures. Descriptive statistics were applied. P-values less than 0.05 were considered statistically significant.
Results
The diagnostic yield of CT-guided bone biopsies was 18%, meaning that in 33 of 181 biopsy cases microbiological analysis identified a pathogen conclusively. In 16/75 (21%) pelvis cases and 9/65 (14%) foot and ankle cases, the microbiological analysis was conclusive for a causative pathogen. 18/33 (55%) conclusive cases also had wound cultures performed, of which 14 (42%) had the same organisms identified in both the wound and bone biopsy specimen cultures. In the 33 cases with conclusive microbiological analysis, the isolated pathogen resulted in adaption of the antibiotic treatment in 31/33 (94%).
Conclusions
CT-guided bone biopsy in patients with chronic non-spinal osteomyelitis may result in the identification of a causative pathogen in only 18% of cases and adaptation of antibiotic treatment in only 17% of cases. Taking into consideration the 42% concordance rate of bone and wound cultures, the diagnostic yield of CT-guided biopsy may decrease to 10%.
Clinical Implications
Our study results indicate a limited role of bone biopsy in the management of patients with chronic non-spinal osteomyelitis. In order to save cost and limit procedure-related morbidity, indications should be considered carefully on a patient-to-patient basis, rather than being ordered for every patient.
