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Updated: Jun 20, 2026
Longitudinal Evaluation of Mouse Hind Limb Bone Loss After Spinal Cord Injury using Novel, in vivo, Methodology
Published on: December 7, 2011
Longitudinal changes in femur bone mineral density after spinal cord injury: effects of slice placement and peel
S Dudley-Javoroski1, R K Shields
1Graduate Program in Physical Therapy and Rehabilitation Science, The University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, USA.
Summary:
Surveillance of femur metaphysis bone mineral density (BMD) decline after spinal cord injury (SCI) may be subject to slice placement error of 2.5%. Adaptations to anti-osteoporosis measures should exceed this potential source of error. Image analysis parameters likewise affect BMD output and should be selected strategically in longitudinal studies.
Introduction:
Understanding the longitudinal changes in bone mineral density (BMD) after spinal cord injury (SCI) is important when assessing new interventions. We determined the longitudinal effect of SCI on BMD of the femur metaphysis. To facilitate interpretation of longitudinal outcomes, we (1) determined the BMD difference associated with erroneous peripheral quantitative computed tomography (pQCT) slice placement, and (2) determined the effect of operator-selected pQCT peel algorithms on BMD.
Methods:
pQCT images were obtained from the femur metaphysis (12% of length from distal end) of adult subjects with and without SCI. Slice placement errors were simulated at 3 mm intervals and were processed in two ways (threshold-based vs. concentric peel).
Results:
BMD demonstrated a rapid decline over 2 years post-injury. BMD differences attributable to operator-selected peel methods were large (17.3% for subjects with SCI).
Conclusions:
Femur metaphysis BMD declines after SCI in a manner similar to other anatomic sites. Concentric (percentage-based) peel methods may be most appropriate when special sensitivity is required to detect BMD adaptations. Threshold-based methods may be more appropriate when asymmetric adaptations are observed.
Insights
Bone mineral density (BMD) in the femur metaphysis declines significantly after spinal cord injury (SCI). Methodological choices in imaging analysis can introduce substantial errors, impacting the interpretation of BMD changes over time.
Area of Science:
- Orthopedics
- Radiology
- Bone Metabolism
Background:
- Assessing interventions for spinal cord injury (SCI) requires understanding longitudinal bone mineral density (BMD) changes.
- Spinal cord injury (SCI) significantly impacts bone density, necessitating accurate measurement techniques.
Purpose of the Study:
- To determine the longitudinal effect of spinal cord injury (SCI) on femur metaphysis bone mineral density (BMD).
- To quantify BMD variations due to peripheral quantitative computed tomography (pQCT) slice placement errors.
- To evaluate the impact of different pQCT peel algorithms on BMD measurements.
Main Methods:
- Peripheral quantitative computed tomography (pQCT) images of the femur metaphysis were acquired from adult subjects with and without SCI.
- Simulated slice placement errors at 3 mm intervals were introduced.
- Images were processed using both threshold-based and concentric peel algorithms.
Main Results:
- Bone mineral density (BMD) showed a rapid decline within 2 years post-spinal cord injury (SCI).
- Operator-selected peel methods resulted in substantial BMD differences, reaching 17.3% in subjects with SCI.
- Slice placement errors can account for up to 2.5% variation in BMD measurements.
Conclusions:
- Femur metaphysis BMD decline after SCI mirrors changes observed in other skeletal sites.
- Concentric peel methods offer higher sensitivity for detecting BMD adaptations in SCI.
- Threshold-based methods may be preferable for identifying asymmetric bone adaptations post-SCI.
