Long-term clinical and occupational outcomes after long segmental arthrodesis for spinal deformity: The Effect of BMI and Smoking

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Multilevel arthrodesis involved in correcting spinal deformity is associated with more complications than short segment spinal fusions. The pre-operative risk factors for complications and inferior outcomes in these patients are not clearly understood.  We studied the impact of 2 specific risk factors, smoking and body mass, on the long-term clinical and occupational outcomes after arthrodesis for spinal deformity.

Prospectively collected data were retrospectively reviewed from 251 patients, age 63 (18-83years) who underwent open posterior instrumented fusion with BMP for spinal deformity from 2002-2011 at one spine center.  All had minimum 2 year clinical and radiographic follow-up.  Fusions averaged 8 levels; 153 had TLIF, 61 had ALIF. The BMI and smoking status of the patient were recorded. Clinical outcomes included perioperative and long-term complications, preoperative and 2 year Visual Analog Pain Scale (VAS) and Oswestry Disability Index (ODI).  Return to work and the ability to remain working long-term were also analyzed, along with job lifting requirements: light, medium, or heavy.  Using logistic regression, the association of BMI and smoking status on outcome measures was analyzed.

At an average follow-up of 5 years (24-131months). Complications included nonunion-20, infection-16, adjacent fractures-28, longterm adjacent degeneration-73. Revision or extension of fusion was required in 68 (27%).  The average BMI was 26.1 (15.5-45.1) with 29 patients who were smokers.  The average preoperative VAS and ODI were 6 (0-10) and 48.16% (0.00-94.0), respectively. At 2 years post-operative the average VAS and ODI were 3.1 (0-10) and 27.8% (0.0-84.0) respectively.  Logistic regression found that neither BMI nor smoking were significant predictors of post-operative VAS and ODI scores.  The only significant predictor of post-operative VAS and ODI scores were preoperative VAS and ODI scores.  Time to return to work and the ability to remain at work long-term was similar smokers vs. nonsmokers.  Though not statistically significant, obese patients took longer to return to work. The overall long-term complication rate was 30% in this study. Smoking and BMI had an Odds Ratio of 1.26 (95% CI 0.54-2.9) and 1.05 (1.00-1.10) for rate of complications.  

At an average 5 years follow-up after multi-segmental arthrodesis for spinal deformity, one quarter of the cohort had undergone additional surgery for adjacent level stenosis, fracture, or instability.  While both smoking and obesity were associated with an increased risk of complications, the difference was not statistically significant.