The Utility of Cervical Spine Bracing As a Postoperative Adjunct to Multilevel Anterior Cervical Spine Surgery

INTRODUCTION

Approximately 132,000 anterior cervical discectomy and fusions (ACDFs) are performed annually in the United States.¹ ACDF is indicated and validated for a wide range of pathologies such as radiculopathy, myelopathy, degenerative disc disease, and degenerative spondylolysis to achieve decompression and fusion with significant improvement in patient outcomes,^2–11 but the use of postoperative bracing following surgery remains contentious. A survey of spine surgeons illustrated the significant variability in postoperative practices by showing more surgeons brace after multilevel ACDF in comparison to single-level ACDF.¹²

Current investigations into the impact of bracing on outcomes in multilevel ACDF reveal mixed results. Rates of pseudarthrosis and perioperative complications have been reported to be increased after multilevel ACDF in comparison to single-level ACDF in part due to distribution of force on a larger construct,^13,14 and the use of bracing has been thought to improve outcomes for the multilevel cases.^15–17 Supporters thus argue that cervical braces decrease pressure and axial load on the construct thereby improving fusion rates. Critics of bracing believe that the internal fixation afforded by an ACDF obviates any requirement for external bracing.^18,19 Biomechanical analyses of cervical braces are also mixed. Some evidence suggests bracing leads to a change in gait affecting patient quality of life and safety,^20–22 whereas other studies report no change in balance when wearing a cervical brace.²³ Cervical braces are also associated with pressure ulcers,²⁴ dysphagia,²⁵ respiratory compromise,²⁶ and restriction of range of motion.^27–29

Therefore, mixed consensus exists regarding bracing after multilevel ACDF, with studies supporting short-term bracing³⁰ and others showing no difference in outcomes.^31,32 We have shown in a previous study that bracing after single-level ACDF shows no difference in outcomes.³³ In this study, we sought to expand upon our prior result by evaluating short-term outcomes and associated direct costs related to cervical bracing following multilevel ACDF.

MATERIALS AND METHODS

Data Collection

Patient data were collected via the NQII EpiLog tool from the electronic health record. Patient age, gender, race, American Society of Anesthesiologists (ASA) score that rates perfect health as 1 and moribund as 5, and comorbidities such as diabetes, chronic obstructive pulmonary disease (COPD), and coronary artery disease (CAD), congestive heart failure (CHF), hypertension, smoking status, pack years, graft type, duration of follow-up, body mass index (BMI), and total number of comorbidities at the time of index surgery were recorded (Table 1). Indicators of outcome were recorded and included increased length of stay (LOS) (Table 2), discharge disposition, emergency room (ER) visit within 30 days, and readmission within 30 days (Figure 1). In a small consecutive prospective pilot, 104 braced and 8 unbraced patients (from the total of 616 patients) completed the EQ-5D-3L questionnaire, a validated measure of health outcomes for cost-utility analysis, to calculate quality-adjusted life years (QALYs). Total cost was calculated as all actual costs directly incurred by the hospital, retrieved from billing databases (Table 2).

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Table 1

Patient demographics and comorbidities.

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Table 2

Comparison of quality and cost of care.

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Figure 1

Short-term postoperative risk assessment. Depiction of odds ratios for short-term outcomes following multilevel ACDF. The braced cohort was compared with the nonbrace cohort in reference to 30-day readmission, ER visits, and discharge to home or to SNF/ARF. Abbreviations: ACDF, anterior cervical spine discectomy and fusion; ARF, assisted rehabilitation facility; ER, emergency room; SNF, skilled nursing facility.

RESULTS

DISCUSSION

In this study, unbraced patients had a reduced likelihood of a home discharge, increased LOS, and increased likelihood of an ER visit within 30 days but no difference in 30-day readmissions. Further, there were no differences in hospital cost or patient-described quality of life. The original description of ACDF in Smith and Robinson's³⁴ paper from 1958 noted that postoperative bracing was generally limited to multilevel ACDF. Internal instrumentation has undergone significant developments since this report; as such, one may expect a decrease in the use of bracing due to the known restriction of neck motion after multilevel fusion.³⁵ The paucity of decisive literature has made it challenging to make an informed decision about bracing in the setting of multilevel ACDF.

There are a few recent studies aimed to address postoperative bracing. In a previous investigation, our group showed no difference in benefit for postoperative bracing following single-level ACDF.³³ Abbott et al³⁰ show a benefit of bracing after ACDF in their study population that included both single and 2-level ACDF. A meta-analysis from Zhu et al³⁶ found that there was no support for postoperative bracing following a number of spine surgeries including ACDF, posterior lumbar arthrodesis, thoracic posterior decompression and fusion, and cervical laminoplasty as measured by patient-reported efficacy, radiographic outcomes, safety, and cost-effectiveness. Unfortunately, the literature still lacks studies that clearly delineate multilevel ACDF from single-level in a broader sample population. Previous studies used narrower study populations, but that does not reflect variability in surgical practice that may affect clinical outcomes.³⁷

Although postoperative bracing is not indicated in every setting, the data here suggest it may have a role in postoperative care for selected cases. There is some evidence to argue that internal instability remains in the postoperative setting because cervical motion is detectable 2 weeks after ACDF independent of the number of levels fused.³⁸ Furthermore, the detrimental effects of smoking on bone health and healing³⁹ leads to lower fusion rates, increased rates of pseudarthrosis, and overall worse outcomes for patients who smoke.^40–43 The decision to brace may thus be better approached from an individualized perspective with consideration of specific comorbidities and corresponding likelihood of complications for a given patient.

From the current study, it is difficult to draw definitive conclusions. With regard to short-term outcomes, the braced patients were 2.68 times more likely to be discharged home and 0.21 times less likely to be in the ER within 30 days of surgery. These findings in conjunction with an increased LOS for those patients who were not braced may indicate that there is some hazard to not bracing following a multilevel ACDF. Interestingly, despite increased LOS in the unbraced cohort, neither the total cost to the hospital nor the QALY gains were different between the 2 cohorts. LOS is known to be a major predictor of cost in ACDF,⁴⁴ but it is not correlated with the total cost data related to the study population here. Furthermore, despite increased likelihood of discharge to SNF/ARF along with increased likelihood of ER visits, the unbraced cohort expressed equivalent improvements in quality of life at 8.8 months. The lack of difference in cost, QALY gains, and the rate of 30-day readmissions contribute to the uncertainty of these results and suggest that nonbracing may be reasonable in some settings.

The cost of cervical braces, which are not included in the total cost calculation presented here, ranges from $25 to $750.⁴⁵ By removing this cost from patients and insurers while providing equivalent results, the removal of postoperative bracing could be the highest value care provided to patients with ACDF.⁴⁶ To verify this, future prospective analysis with a balanced population size is necessary to determine whether foregoing a brace is a safe and effective option.

This study aimed to assess the efficacy of bracing in a broad and heterogeneous multilevel ACDF population. The study population was constructed such that surgeon-specific practices of strictly bracing or not bracing patients following multilevel ACDF removed bias of patient selection, which was confirmed in the similarity between the 2 cohorts. All patients received anterior plating, but graft type was not controlled for and showed significant differences between the 2 cohorts. Further, there were important differences between cohorts, with more ASA 2 patients in the braced cohort and more ASA 3 patients in the unbraced cohort. Nevertheless, there was no difference in 30-day readmissions between the 2 groups. This analysis was not powered to determine if differences in graft-type or surgical choice generated differential short-term outcomes in these patients, but again this study intended to include variability in patient presentation and surgical practice in order to generalize results to all elective multilevel ACDF cases.

This study is limited by its retrospective cohort design despite the use of the prospective data gathering NQII EpiLog tool. Recording bias is a potential problem with the retrospective design and cannot be avoided. To this end, we report data as means and standard deviations without removing outliers to prevent selection bias. All patients included in the study are reflective of the spectrum of complexity in ACDF cases seen at this institution. There is a limited number of patients with QALY gains data, which results in a small sample size for this metric, but it was a planned secondary measure within the study design to act as a confirmatory measure. In future prospective studies, a focus on gathering QALY data will be able to confirm these results. In this study, we assess the early impact of bracing, however, we do not assess long-term pseudarthrosis rates. It will be important to assess for presence of spinal fusion in long-term analysis.

Due to the imbalance in sample size between the 2 cohorts, the authors were unable to analyze the data set with the strictest statistical measures. The univariate analyses reported above are representative of the relationship between bracing and patient outcomes but are not able to incorporate preoperative variables in the analysis. We aim to expand the population to generate a propensity score-matched trial design to further control for the differing demographic variables. Further equivocal results would suggest the value of a prospective randomized control trial.

The results of this study are inconclusive on the short-term use of bracing following multilevel ACDF, however, the data suggest that major markers of negative outcome (hospital readmission, postoperative health care related quality of life) are comparable with or without bracing. The use of postoperative bracing remains a common practice, and the data reported here do not clearly indicate its need or absence thereof, despite reduced LOS and increased home disposition. These mixed results warrant future prospective investigations to delineate if there are true differences in short-term outcomes with cervical bracing following ACDF, as well as long-term studies that assess patient-reported outcome measures, fusion rates, and re-operation rates.