Date of Award

January 2015

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)



First Advisor

Jonathan N. Grauer

Subject Area(s)



Complications following spine surgery are widely reported but poorly characterized. The effect of preoperative comorbidities and postoperative complications on length of stay (LOS) has not been evaluated. It would be ideal to have a clearer understanding of the variables affecting LOS to facilitate setting expectations and control costs. Using complications and LOS as outcomes, we can also characterize the risks inherent with surgical practices, such as the use of iliac crest bone graph (ICBG) in spinal fusion.

The study consisted of three aspects. First, the effect of pre and perioperative variables on LOS for 103 patients undergoing posterior lumbar fusion at Yale was examined. Next, the National Surgical Quality Improvement Program (NSQIP) database was used to determine the variables associated with extended LOS and complications following 2,164 anterior cervical discectomy and fusion (ACDF) procedures. Finally, 13,927 spinal fusion cases from the NSQIP database were analyzed to determine the effect of harvesting ICBG on operative time, complications, LOS, and readmission. Multivariate analysis was used throughout the study to control for confounding while evaluating statistical significance.

For lumbar fusion, average LOS was 3.6 ± 1.8 days. 79% had a stay of four days or less. Preoperative variables associated with increased LOS were age and ASA score. Heart disease was significantly associated with decreased LOS. Postoperative complications occurred in 32% of patients and led to a LOS of 5.1 ± 2.3 days vs. 2.9 ± 0.9 days for patients with no complication. For ACDF, average LOS was 2.0 ± 4.0. Age ≥ 65, functional status, transfer from facility, preoperative anemia, and diabetes were the preoperative factors predictive of extended LOS. Major complications, minor complications, and extended surgery time were the perioperative factors associated with increased LOS. 71 (3.3%) had a total of 92 major complications. ASA score ≥ 3, preoperative anemia, age ≥ 65, extended surgery time and male gender were predictive of major complications. Meanwhile, postoperative blood transfusion (OR 1.5), extended operative time (+ 22.0 min) and LOS (+0.2 days) were significantly associated with ICBG use.

After lumbar fusion, patients that are older and have widespread systemic disease tend have longer LOS, but no single comorbidity was predictive of LOS. After ACDF, 1 in 33 patients develops a major post-operative complication, which are associated with an increased LOS of 5 days. Current ICBG usage in spinal fusion is low, with rates between 3.4% and 12.4% depending on approach. Use of ICBG is associated with extended operative time, extended LOS, and postoperative blood transfusion.