Outcomes and complications following spinous process fixation: a single-center analysis of 192 cases

Spinous process fixation (SPF) is presented as less invasive than pedicle screws. There has been little quantitative data to support this assertion, and "minimally invasive" has not been well defined in spine surgery. Length of stay (LOS) and blood loss (BL) were chosen as surrogate measures of "minimally invasive." A chart review was conducted on 192 lumbar fusion patients (374 levels). A backward-selection multiple-linear-regression was performed to determine what variables contribute to LOS and estimated blood loss (EBL). A logistic regression controlling for age and number of levels on complication rates was also performed. Number of levels with supplementary screw fixation (SSF) was significantly associated with LOS (p = 0.003). Controlling for number of surgical levels, LOS increased by 0.30 days (95% CI: 0.02-0.58) for each level with SSF. For each additional level including SSF, BL increases by 25.31 cc (95% CI: 3.50-47.12, p = 0.023). Interbody fusion increases blood loss by 68.16 cc (95% CI: 17.18-119.13, p = .009). For each additional level with SSF, odds of perioperative complications increase by OR = 2.34 (95% CI: 1.35-4.05). Long-term complications were not affected by instrumentation. LOS and BL are increased in patients with SSF vs. SPF only. Odds of perioperative complications are increased in patients with SSF relative to those treated with SPF alone.