Osteomyelitis of the pelvic bones in patients with spinal cord injury: Is magnetic resonance useful for preoperative diagnosis?

Aim of the study: We report a prospective, observational, single-centre study on adult patients with spinal cord injury (SCI) and pressure sores undergoing surgical debridement and reconstruction at Montecatone Rehabilitation Institute from July 2013 to January 2016. The aim is to assess usefulness of magnetic resonance (MR) in pre-operative diagnosis of osteomyelitis. Materials and methods: All the patients underwent preoperative MRI each MRI was evaluated independently by two radiologists and the exam was considered positive for osteomyelitis only when the two radiologists agreed on the diagnosis. All the surgical procedures consisted of a wide debridement of soft and bony tissues and reconstruction: bone specimens were collected and sent for culture and histopathological evaluation. Results of MRI and histopathology were compared. Results: 85 patients were included in the study. The two radiologists working independently agreed on the diagnosis of osteomyelitis in 96% of the cases. Pre-operative MRI was considered positive for osteomyelitis in 45 cases. According to histology, osteomyelitis was diagnosed in 40 patients. MRI findings and histology were concordant in 61% of cases; 19 false positive and 14 false negative cases were found. Sensitivity and specificity of MR in the diagnosis of osteomyelitis were 65% and 58% respectively, with a positive predictive value of 58% and a negative predictive value of 65%. Conclusion: In our cohort sensitivity, specificity, positive predictive value and negative predictive value of MR for the diagnosis of osteomyelitis in patients with SCI and pressure ulcers are lower than previously described. Our findings suggest that MRI cannot be considered a reliable diagnostic technique for the diagnosis of osteomyelitis. We can conclude that MRI is not indispensable pre-operatively in SCI patients with pressure sores, and that all the patient should undergo a wide soft and bony tissues debridement as if they were all affected by osteomyelitis. Histological diagnosis is useful to decide the timing of antimicrobial therapy, that should be planned based on the results of the surgical specimen culture. Further studies are needed to investigate this topic.