title: Risk factors for the development of deformity in patients with spinal infection.
abstract: OBJECTIVE
  Bacterial spinal infections are infrequent but may lead to significant morbidity and death. Apart from neurological complications, infections may also lead to bone destruction resulting in deformity of the spine. However, the incidence of spinal deformities and risk factors is not well characterized in the literature.
  
  
  METHODS
  A retrospective cohort study was conducted using electronic medical records at a single institution. All patients were over 18 years of age and had a clinically and radiologically documented spinal infection that was treated surgically during the period 2006-2013. Infections were classified according to anatomical location including disc, bone, and/or epidural space. Deformities included kyphosis and/or subluxation. The authors analyzed risk factors for developing at least 1 deformity between the time of infection and operation using the Fisher exact test and chi-square test. Change in visual analog scale (VAS) scores preoperatively versus postoperatively was also analyzed using the paired t-test.
  
  
  RESULTS
  The study included 48 patients. The most common types of spinal infections were osteomyelitis and discitis (31%); osteomyelitis, discitis, and spinal epidural abscess (SEA; 27%); SEA only (15%); and osteomyelitis only (13%). Overall, 21 (44%) of 48 patients developed a spinal deformity. Anatomical location of infection (bone and/or disc and/or epidural space) was significantly associated with development of deformity (p < 0.001). In particular, patients with SEA had lower odds of deformity compared with patients without SEA (odds ratio 0.2, 95% confidence interval 0.05-0.9; p < 0.001). No other factor was significantly associated with deformity. Pain measured by VAS score tended to improve by a mean of 1.7 ± 2.7 points (p < 0.001) when comparing preoperative to postoperative scores.
  
  
  CONCLUSIONS
  In this cohort of patients, 44% developed at least 1 deformity, predominantly kyphosis. The only variable significantly associated with deformity was infection location. Patients with SEA alone demonstrated lower odds of developing a deformity compared with patients without SEA. Other analyzed variables, including age, body mass index, time from initial diagnosis to surgery, and comorbidities, were not found to be associated with development of deformity. Surgical intervention resulted in pain improvement.
authors.affiliation: Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan.
authors.forename: Dushyanth
authors.initials: D
authors.lastname: Srinivasan
authors.forename: Samuel W
authors.initials: SW
authors.lastname: Terman
authors.forename: Mai
authors.initials: M
authors.lastname: Himedan
authors.forename: Domenico
authors.initials: D
authors.lastname: Dugo
authors.forename: Frank
authors.initials: F
authors.lastname: La Marca
authors.forename: Paul
authors.initials: P
authors.lastname: Park
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001424:Bacterial Infections / Q000150:complications*; D015331:Cohort Studies; D057286:Electronic Health Records / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013118:Spinal Cord Diseases / Q000150:complications* / Q000175:diagnosis / Q000382:microbiology* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D064232:Visual Analog Scale; D055815:Young Adult
keywords: BMI = body mass index; SEA = spinal epidural abscess; VAS = visual analog scale; discitis; kyphosis; osteomyelitis; spinal deformity; spinal epidural abscess; spinal infection; subluxation