Background: Spinal infection accounts for 2-7% of all musculoskeletal infections. Surgical treatment is normally indicated in concurrent neurological deficit that requires decompression, and in failure of medical treatment. Spinal deformity and instability are also potential indications for surgical treatment. Few studies have investigated the factors associated with deformity progression.

Objective: To investigate the incidence of and factors associated with the development of spinal deformity in non-tuberculous spinal infection.

Materials and methods: A retrospective review of patients diagnosed with spinal infection by clinical and imaging study at Siriraj Hospital (Bangkok, Thailand) during January 2009 to December 2015 was conducted. The exclusion criteria were suspected or confirmed diagnosis of tuberculous infection, age under 18 years, no radiographic study available, and/or loss to follow-up before 6 months. Radiographic parameters at initial presentation and at follow-up were recorded. Cobb angle that changed more than 10 degrees, or vertebral height loss of more than 15% compared to the initial measurement were defined as deformity.

Results: There were 62 non-tuberculous spinal infections included in this study. There were 30 females and 32 males with a mean age of 61.3 years (range 28-89). The most common site of infection was lumbar spine (65.1%), followed by thoracic spine (26.7%) and cervical spine (7.9%). Location of infection was significant factor associated with deformity(p=0.006) Causative pathogen was identified in 35 patients (56.5%). The most frequently observed organism was S. aureus (16.1%), followed by E. coli and S. agalactiae (both 9.7%). Spinal deformities were detected in 39 patients (62.9%). Surgical treatment was performed in 35 patients (56.5%).

Conclusion: In this study, 62.9% of patients developed deformity, and more common in the lumbar spine. Location of the infection and number of the infected vertebrae are the significant factors associate with deformity progression.

Keywords: Spinal deformity, spinal infection, spondylodiscitis, osteomyelitis, bacteria, non-tuberculous