Key-words:
Lumbar fusion - posterior lumbar spine fusion - single-level bracing
Introduction
Postoperative bracing is a commonly employed adjunct following posterior lumbar fusion
(PLF), emerging from several early long-term studies of PLF using bracing as standard
postoperative care.[[1]],[[2]] Surveys of postoperative practices have shown that roughly half of the practitioners
utilize bracing following PLF.[[3]],[[4]] Theoretically, immobilization from an external brace should provide additional
support against axial loading on an immature construct as well as limiting truncal
motion, thereby improving fusion rates and decreasing pseudarthrosis. Some proponents
of bracing additionally maintain that bracing can improve postoperative pain. However,
the true utility of postoperative bracing following lumbar fusion is controversial.
Conflicting data from both clinical outcomes and biomechanical perspective have led
to a lack of guidelines regarding optimal postoperative practices.
Those in favor of bracing point to studies demonstrating an overall decrease in applied
force to the spine with bracing[[5]] leading to decreased rates of pseudarthrosis.[[6]] Proponents of postoperative bracing also argue that the psychological or proprioceptive
reminder of limiting movement is another important component of the utility of postoperative
bracing. Practitioners who oppose bracing note that this purported benefit is difficult
to measure objectively.[[4]] Arguments against bracing point to recent studies, which demonstrate no significant
difference in quality of life or pain relief at short-term[[7]],[[8]] and long-term follow-up[[9]] for braced and unbraced patients. In addition, custom-fit lumbar braces have an
average cost of $2,471.04, which increases overall health-care dollars spent per surgical
intervention.[[10]]
These disparate findings are representative of an overall lack of consensus regarding
best practices. To more definitively outline the utility of bracing following PLF,
in our present study, we sought to retrospectively evaluate short-term postoperative
outcomes and cost in braced and unbraced cohorts following single-level PLF.
Methods
Study population
In this institutional review board-approved study, patients undergoing single-level
PLF at a three-hospital, 1659-bed Urban University health system were enrolled retrospectively
from July 1, 2013, to June 30, 2017. The Neurosurgery Quality Improvement Initiative
(NQII) EpiLog tool provided prospective data acquisition on consecutive patients (n
= 906). Briefly, the NQII EpiLog tool is a nonproprietary clinical research and quality
improvement architecture that was built and overlaid onto the electronic health record
system, which enables prospective data collection.[[11]]
All patients, over the age of 18, undergoing elective single-level PLF performed by
neurosurgeons at the institution studied herein were included in the analysis. The
study population was separated into braced and unbraced cohorts. The two study cohorts
were separated based on the attending surgeon's practice – of the 20 neurosurgeons
at the health system, a subset never braced patients for single-level PLF. Remaining
cases were confirmed as elective with records of office visits 30 days before the
surgery for evaluation and imaging. Intraoperative technique and instrumentation used
were at each surgeon's discretion.
Data collection
Patient data were collected through the NQII EpiLog tool from the electronic health
record. Patient age, gender, race, the American Society of Anesthesiologists score
that rates perfect health as 1 and moribund as 5, and multiple medical comorbidities
[[Table 1]] were recorded. Surgical site infection (SSI), length of stay (LOS), discharge disposition,
emergency room (ER) visit within 30 days, and readmission within 30 days were also
recorded. Of total 616 patients, 104 braced and 8 unbraced patients completed the
EQ-5D-3L questionnaire, a validated measure of health outcomes for cost–utility analysis,
to calculate quality-adjusted life year (QALY) for a small subset prospective pilot
study. The total cost was calculated as all actual costs directly incurred by the
hospital during the inpatient stay, retrieved from billing databases. All continuous
variables were assessed with the Student t-test or Wilcoxon rank-sum test where appropriate.
All categorical variables were analyzed with Pearson's Chi-square test or Fisher's
exact test. Multivariate logistic regression analyses were used to determine disposition
location based on the independent variable of bracing. Significant results were defined
as P < 0.05. Averages are presented as mean ± standard deviation.
Table 1: Demographics data for the study population separated by cohort
Results
Patient demographics [[Table 1]]
Among the study population, 863 patients were braced and 43 were not braced. There
was no difference in graft type (P = 0.145) or comorbidities (P = 0.20–1.00) such
as obesity (P = 1.000), smoking (P = 1.000), chronic obstructive pulmonary disease
(P = 1.000), hypertension (P = 0.805), coronary artery disease (P = 1.000), congestive
heart failure (P = 1.000), and problem list number (P = 0.228). The braced group incurred
a significantly higher direct cost (median increase of 41.43%, P < 0.001) compared
to the unbraced cohort (bracing cost excluded). No difference was seen between the
two groups in LOS (P = 0.836), discharge disposition (P = 0.226), readmission (P =
1.000), ER visits (P = 0.281), SSI (P = 1.000), and QALY gain (P = 0.319). The follow-up
was 244 days on average (median: 118 days).
Postoperative setting
No difference was seen between the braced and unbraced cohorts in LOS (P = 0.836),
discharge disposition (P = 0.226), readmission (P = 1.000), or postoperative ER visits
(0.281). In addition, there was no difference in number of SSI following surgery between
the two groups (P = 1.000) [[Table 2]] and [[Figure 1]].
Table 2: Postoperative setting
Figure 1: Odds ratios of short-term postoperative risk assessment
Cost analysis and quality
No significant difference was seen in QALY gain (P = 0.319). Assessment of the total
direct cost of hospitalization revealed that the braced group incurred a significantly
higher direct cost than the unbraced cohort (median increase of 41.43%, P < 0.0001)
[[Table 3]].
Table 3: Comparison of length of stay and cost for the two cohorts
Discussion
Clinical decision-making about the application of postoperative bracing for PLF is
variable. In this retrospective cohort study, no significant difference in postoperative
course or early adverse events between bracing and not bracing following single-level
PLF was noted. We assessed patients undergoing single-level PLF at our institution
over 4 years, analyzing total cohorts of 863 braced and 43 unbraced. Furthermore,
in cost analyses of these two postoperative populations, we show that those patients
who were braced following PLF incurred higher direct costs when comparing the median
increase of cost. Intraoperative costs are presumably similar for intraoperative costs
by virtue of limiting the population to single-level operations. We hypothesized that
those unbraced patients may be prone to increased resource utilization for fear of
increased complications, but these results demonstrate that this was not the case,
and the unbraced patients thereby had similar and less expensive hospital courses.
Prior studies of bracing following lumbar fusion show varied results. Major arguments
for bracing are that it aids in postoperative pain control, improves integrity of
and promotes fusion of hardware construct by decreasing load on the construct, and
serves as a proprioceptive reminder of a recent surgery. With the exception of the
latter, which is difficult to study, arguments against bracing are founded on studies
that have attempted to disprove these arguments, including those describing the lack
of difference in postoperative pain[[9]] and lack of significant biomechanical advantage to bracing.[[12]],[[13]]
Differences in these measures would theoretically lead to a difference in adverse
outcomes in the postoperative setting. We found no significant difference in LOS and
return visits to the emergency department within 30 days. These factors can produce
barriers to return to function and can be drivers for overall health-care cost increase.
QALY is a more direct metric of disease burden, and we found no significant difference
between the braced and unbraced cohorts in this measure in a small prospective pilot
subgroup. Moreover, we show that there is an overall increase in direct costs for
patients who underwent bracing postoperatively. Brace costs are not insignificant,
with off-the-shelf thoraco-lumbo-sacral orthoses, a commonly utilized brace following
PLF, costing over $1000, which is nearly doubled if a custom-fit brace is required.[[10]] These findings suggest that the addition of bracing in postoperative management
does not provide added benefit and may also result in higher overall costs. Given
findings in previous studies supporting the lack of efficacy of bracing across various
presumed areas of benefit, and our findings here showing no major difference in multiple
important short-term postoperative metrics, the elimination of postoperative bracing
following single-level PLF may represent a safe, more cost-effective management strategy.
Limitations
There are important limitations to this study. Open PLF is an overarching category
of spine surgery; there are different surgical approaches to achieve a PLF. These
are dependent on operator preference and comfort. In this study, we have not separated
approaches to lumbar fusion. As such, differing practices may yield different postoperative
results that cloud the data. However, rather than restricting the study to a single
type of instrumentation or operative technique, we believe that these results do reflect
heterogeneity in operative techniques and thereby retain external validity. In addition,
there is a multitude of braces available, which we did not standardize for in our
retrospective study. Postoperative outcomes again may differ based on the brace type.
Interestingly, despite this variation in bracing pattern, overall costs remained increased.
Another important limitation is the statistical analysis in this study. We were limited
by an imbalance in sample size between the two cohorts. 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. The designation
of being braced or unbraced was a feature of standardized surgeon-specific practice;
some neurosurgeons braced all of their patients while others braced none of their
patients. The dichotomous practices prevent overt selection bias on a case-by-case
basis although there could still be biases on which cases each neurosurgeon elected
to do. To this end, the cohort demographic analysis does not suggest that there is
any significant difference between the braced and unbraced cohorts in this study.
Further study will be needed to expand the population, focus on long-term outcomes,
and potential for a randomized study.
Conclusion
In this retrospective study of bracing following open PLF, we describe short-term
data that suggest that removal of bracing from the postoperative regimen for PLF will
not result in increased adverse outcomes but will reduce cost. Long-term analysis
of risk and fusion rates is necessary before the elimination of postoperative bracing
from postoperative management strategies.
