Relationships between image-based and mechanical bone properties with pain in knee osteoarthritis
Date
2018-08-28
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Type
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Degree Level
Doctoral
Abstract
Pain is the predominant symptom of OA, a debilitating disease marked by changes in cartilage
and subchondral bone, but pain pathophysiology is poorly understood. Bone is densely
innervated and may be linked to OA-related knee pain. Quantitative computed tomography
(QCT) is an in vivo image-based technique with the potential to quantify bone mineral density
(BMD) to explore the role of bone in OA-related pain. When coupled with subject-specific finite
element (FE) modeling, it may be possible to clarify the mechanical role of bone in OA-related
knee pain.
The objectives of this study were to assess if: 1) tibial subchondral BMD is associated
with OA-related nocturnal knee pain using depth-specific QCT image processing, 2) tibial
epiphyseal and metaphyseal BMD is associated with OA-related knee pain using a modified
depth-specific CT image processing tool, 3) subchondral cyst characteristics are associated with
OA-related knee pain, and 4) FE-derived mechanical outcomes at the proximal tibia are
associated with OA-related pain.
Lateral focal subchondral BMD was 33% higher in participants with severe nocturnal
pain than participants with no nocturnal pain at the 2.5-5mm depth (p=0.028) and 32% higher at
5-10mm from the subchondral surface (p=0.049). At the epiphyseal and metaphyseal depths,
higher total pain was associated with lower medial epiphyseal BMD (R2=-0.40, p=0.002), and
lower metaphyseal BMD (R2=-0.35, p=0.017). At the lateral region, subchondral cyst number
(r=0.55, p<0.001) and cyst number per proximal tibial volume (r=0.52, p<0.001) were both
associated with BMD, and lateral cyst number and volume were associated with joint space
narrowing (r=0.52 to 0.68, p<0.001) and alignment (r=0.44 to 0.62, p<0.001). In our FE study,
principal compressive stress was associated with nocturnal pain at most lateral regions (r=0.33
to 0.50, p<0.05). Principal compressive stress at the lateral region ranged from 47% to 67%
higher (p<0.05) in participants with severe nocturnal pain than participants with no pain.
This series of studies suggests that pain in patients with knee OA may be associated with
BMD throughout various depths at the proximal tibia as well as FE-based bone mechanical
outcomes, such as principal compressive stress. These findings suggest previously unexplored
associations between OA-related knee pain and BMD or mechanical outcomes, emphasizing that
bone may have a mechanical role in OA-related pain pathogenesis.
Description
Keywords
Bone, Pain, Osteoarthritis, Bone Mineral Density, Finite Element Modelling, Computed Tomography
Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Biomedical Engineering
Program
Biomedical Engineering