2014 Research Grant Award Winner
Importance of Spinal Muscle Function on
Intervertebral Disc and Facet Joint Health
John M. Popovich Jr, PhD, DPT, ATC
Background Context: Spinal muscles are important to ensure
spinal stability, which has led to the advancement of minimally
invasive surgeries and other surgical techniques that minimize
damage to spinal muscles. Despite these advances, there remains a critical need to determine the relationship between
spinal muscle function and spine health.
Purpose: This project aimed to investigate the relationship
between muscle function and spine health by experimentally impairing spinal muscle function (botulinum toxin type A (BTX-A)
injection) and determining the morphological and histological
changes to the spinal anatomy (muscles, intervertebral disc and
facet joints) in a rabbit model.
Study Design/Setting: Radiological and histological laboratory experimental design using a rabbit model.
Patient Sample: Annulus cells from three normal Thompson
grade I discs, and 7 grade II, 7 grade III, 11 grade IV and 1 grade
V surgical specimens.
Outcome Measures: Neurite lengths, neurotrophin media
levels from nerve-annulus co-culture or CM; correlations
between lengths and neurotrophin levels.
Methods: A total of 28 New Zealand White (NZW) rabbits
were used for this study, consisting of two experimental
groups and one control group. The two experimental groups
were injected with either 3. 5 Units/kg or 8.0 Units/kg of
botulinum toxin type-A (BOTOX, Allergan, Irvine, CA) in the
lumbar erector spinae musculature, respectively. The control
group was injected with saline. Rabbits were evaluated using
a Bruker 7.0 Tesla preclinical magnetic resonance imaging
(MRI) system (BioSpec 70/30 USR, Billerica, MA) at baseline
and serially (at least every other week) for either 8 weeks or
24 weeks. MR images were used to determine morphological
changes of the muscle, intervertebral disc and facet joints at
their final time point (before euthanasia). After euthanasia,
histology was performed to determine morphology (
hematoxylin and eosin) and proteoglycan content (Safranin-O) of
the intervertebral discs and facet joints. Statistical analyses
were performed between the three groups with statistical
significance set to p<0.05.
Results: Following BTX-A injections, there was progressive
paraspinal muscle atrophy and fatty infiltration that was
confirmed on both MRI and histology. Muscle cross-sectional
area (CSA) significantly decreased at each spinal level for the
3. 5 Unit/kg and 8.0 Unit/kg BTX-A groups and was more pro-
nounced in the higher dosage group (p<0.05). Fatty infiltration
was also observed on the MR images in both BTX-A groups.
Histological analysis confirmed the presence of adipocytes in
the erector spinae muscles, validating the MRI fatty infiltration
findings. There were no significant differences between groups
for MRI analysis of disc height, disc signal intensity decreases
or facet joint angle changes (p>0.05) at either the 8-week or
24-week time point. There were also no significant differences
between groups for histological analyses of the intervertebral
discs or facet joints. A decrease in proteoglycan staining was
noted in a select number of facet joints at the 24-week time
period in both the 3. 5 Unit/kg and 8.0 Unit/kg BTX-A groups,
which was not present in the saline group; however, this find-
ing was not statistically significant.
Conclusions: In conclusion, this preliminary investigation
demonstrates the ability to significantly induce morphological
changes to the lumbar paraspinal muscles of the NZW rabbit,
though there were no statistically significant changes to the
intervertebral discs or facet joints. Additional studies investigating injections into different muscles (eg, multifidus) and
extended time points are currently underway.
FDA Device/Drug Status: This abstract does not discuss or
include any applicable devices/drugs.
2014 Research Grant Award Winner
Patient and Provider Behavior Change Associated with
Low Back Pain Bundled Payments: A Propensity Score
Matched Cohort Study
Joel M. Stevans, DC, PhD; Alex Kimp, DPT; Lauren Terhorst, PhD;
Dino Rovito, MS, PT; Anthony Delitto, PT, PhD
Study 1: Patient as Unit of Analysis
Introduction: Value-based insurance design seeks to lower or
remove financial barriers that may inhibit or prevent patients
from seeking high-value services. The goal of this approach is
to reduce patients’ out-of-pocket costs, such as copayments,
to facilitate their use of effective services. In January 2012, a
large regional health plan instituted a novel bundled payment
reimbursement strategy that covers eight weeks of physical
therapy for commercially insured patients with select low back
pain (LBP) diagnoses. Under this reimbursement methodology patients presenting to physical therapy with a qualifying
diagnosis are only responsible for a single copayment regardless of the amount of care they receive during an eight-week
Methods: A retrospective observational study was conducted
to compare physical therapy utilization in adult LBP patients
subject to single per episode copayments (ie, intervention)
versus those with multiple per visit copayments (ie, control).
Complete eight-week episodes of care were constructed for
patients treated within the outpatient physical therapy setting
from January 2012 through June 2013. The primary outcome
was the number of physical therapy visits per eight-week episode of care. Propensity score matching was used to assemble