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The effective forces transmitted by high-speed, low-amplitude thoracic manipulation
1Human Performance Laboratory, University of Calgary, Calgary, Alberta, Canada. walter@kin.ucalgary.ca
Spine
|November 8, 2001
Summary
This study found that local forces during spinal manipulative therapy are much lower than global measures suggest, as increased contact area distributes force. This highlights the need to consider local loading in risk-benefit assessments for these treatments.
Area of Science:
- Biomechanics
- Spinal Manipulative Therapy
- Musculoskeletal Research
Background:
- Current understanding of spinal manipulative therapy (SMT) mechanics relies on global force/pressure measurements.
- Global measures may lead to inaccurate conclusions regarding SMT's effects, internal loading, and risks.
- Sparse data exists on the localized mechanical forces applied during SMT.
Purpose of the Study:
- To quantify local loading measures during thoracic spinal manipulative treatments.
- To compare these local loading measures with traditional global measures.
- To inform more accurate risk-benefit assessments of SMT.
Main Methods:
- Twenty asymptomatic volunteers received three high-speed, low-amplitude (HSLA) thrusts to the thoracic spine.
- A flexible pressure pad measured total force, local force, contact area, and pressure.
- Nonparametric statistics were used to compare local and global loading measures.
Main Results:
- Average peak total force was 238.2 N.
- Average peak local force over a 25 mm² area was only 5 N.
- Global measures significantly overestimate the local effective forces at the target site.
Conclusions:
- This study is the first to quantify local loading and compare it to global measures in HSLA SMT.
- Effective local loading is substantially lower than global measures indicate due to increased contact area.
- Risk-benefit assessments for HSLA SMT should incorporate local loading measures for greater accuracy.