Osteomyelitis associated with pressure sores

Abstract

Background: Pressure sores may be associated with underlying osteomyelitis that is difficult to differentiate clinically from infection or colonization of adjacent soft tissue. Cultures of bone specimens are frequently contaminated with organisms residing in adjacent soft tissue. The three objectives of this cohort study were to (1) determine the accuracy of clinical evaluation for osteomyelitis; (2) evaluate the potential role of quantitative cultures of bone in differentiating osteomyelitis from soft-tissue infection or colonization; and (3) assess the impact of treating osteomyelitis on the outcome of pressure sores.

Methods: Thirty-six patients with pressure sores related to spinal cord injury or cerebrovascular accident underwent clinical evaluation for osteomyelitis, followed by percutaneous needle biopsy of bone. Routine semiquantitative and quantitative, aerobic and anaerobic cultures of bone specimens were performed. Pathologic examination of bone tissue was used as the standard criterion for diagnosing osteomyelitis.

Results: Six (17%) of 36 patients were diagnosed by pathologic examination as having osteomyelitis. The sensitivity and specificity of clinical evaluation were 33% and 60%, respectively. When positive, quantitative bone cultures yielded a similar number of bacterial isolates and a comparable range of bacterial concentration in patients with osteomyelitis vs those without osteomyelitis. Pressure sores healed in all six patients with osteomyelitis after appropriate therapy.

Conclusions: Clinical evaluation for osteomyelitis is often inaccurate. Pathologic examination of bone tissue is required for definitive diagnosis of osteomyelitis. Quantitative bone cultures do not help differentiate osteomyelitis from infection or colonization of adjacent soft tissue. It is possible that treatment of osteomyelitis may improve the outcome of associated pressure sores.