Impact of subsidence on clinical outcomes and radiographic fusion rates in anterior cervical discectomy and fusion: a systematic review.

STUDY DESIGN: Systematic review. OBJECTIVE: To provide a systematic review of published literature on the impact of subsidence on clinical outcomes and radiographic fusion rates after anterior cervical discectomy and fusion with plates or without plates. BACKGROUND: Subsidence of interbody implants is common after anterior cervical spine fusions. The impact of subsidence on fusion rates and clinical outcomes is unknown. METHODS: Systematic literature review on published articles on anterior cervical discectomy and fusion, which objectively measured graft subsidence, radiographic fusion rates, and clinical outcomes between April 1966 and December 2010. RESULTS: A total of 35 articles that measured subsidence and provided fusion rates and/or clinical outcomes were selected for inclusion. The mean subsidence rate ranged from 19.3% to 42.5%. The rate of subsidence based on the type of implant ranged from 22.8% to 35.9%. The incidence of subsidence was not impacted by the type of implant (P=0.98). The overall fusion rate of the combined studies was 92.8% and was not impacted by subsidence irrespective of subsidence definition or the measurement technique used (P=0.19). Clinical outcomes were evaluated in 27 of 35 studies with all studies reporting an improvement in patient outcomes postoperatively. CONCLUSIONS: Subsidence irrespective of the measurement technique or definition does not appear to have an impact on successful fusion and/or clinical outcomes. A validated definition and standard measurement technique for subsidence is needed to determine the actual incidence of subsidence and its impact on radiographic and clinical outcomes.

Disparities in the outcomes of lumbar spinal stenosis surgery based on insurance status.

STUDY DESIGN: Retrospective cohort study using Thomson Reuter's MarketScan database. OBJECTIVE: To evaluate the extent to which Medicaid versus commercial insurance status affects outcomes after lumbar stenosis surgery. SUMMARY OF BACKGROUND DATA: The Affordable Care Act aims to expand health insurance and to help narrow existing health care disparities. Medicaid patients have previously been noted to be at an increased risk for impaired access to health care. Conversely, those with commercial insurance may be subject to overtreatment. We examine the surgical treatment of low back pain as an example that has raised significant public health concerns. METHODS: A total of 28,462 patients, ages 18 and older, were identified who had undergone laminectomy or fusion for spinal stenosis between 2000 and 2009. Patients were characterized by baseline demographic information, comorbidity burden, and type of insurance (Medicaid vs. commercial insurance). Multivariate analysis was performed comparing the relative effect of insurance status on reoperation rates, timing and type of reoperations, postoperative complications, and total postoperative health resource use. RESULTS: Medicaid patients had similar reoperation rates to commercially insured patients at 1 year (4.60% vs. 5.42%, P = .38); but had significantly lower reoperation rates at 2 (7.22% vs. 10.30%; adjusted odds ratio [aOR] = 0.661; 95% confidence interval [CI], 0.533-0.820; P = .0002) and more than 2 years (13.92% vs. 16.89%; aOR = 0.722; 95% CI, 0.612-0.851; P <.0001). Medicaid patients were particularly less likely to undergo fusion as a reoperation (aOR = 0.478; 95% CI, 0.377-0.606; P < 0001). Medicaid patients had greater health care resource utilization as measured by hospital days, outpatient services and medications prescribed; however, commercially insured patients had significantly higher overall health utilization costs at 1 and 2 years. CONCLUSION: There are insurance disparities that affect important surgical outcomes after initial surgery for spinal stenosis. Efforts for national health care reform should include explicit efforts to identify such system factors that will reduce current inequities in care. LEVEL OF EVIDENCE: 2.