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Passive Care Research for Doctors
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Theraputic Ultrasound
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1. Forslund, C et al. Effects of high-intensity focused ultrasound on the intervertebral disc: a potential therapy for disc herniations. J Clin Ultrasound. 2006 Sep; 34 (7):330-8.
The purpose of this study was to determine the potential application of high-intensity focused ultrasound for the minimally invasive treatment of herniated intervertebral discs by developing a probe that produces sufficiently high temperature locally to shrink collagen fibers.
A 5-mm ultrasound probe was produced with a geometric focal length of 15 mm.
The probe produced 2.5 W of acoustic power and was operated at a frequency of 4.1 MHz.
Measurements of temperature increase were performed in discs from bovine tails.
In vivo experiments were performed to assess histological changes in the disc as well as in nerve root and muscle.
RESULTS:
- Sufficient temperature increase to produce collagen shrinkage was observed close to the focus of the ultrasound.
- Temperature measurements in vertebral end plates showed a temperature increase of only 4 degrees Celsius after 60-second exposure of the disc.
- In vivo experiments revealed histological changes in the disc consistent with collagen shrinkage, with no adverse effects seen in surrounding tissues.
CONCLUSIONS:
The experiments demonstrated the feasibility of high-intensity focused ultrasound in the treatment of contained herniated discs.
2. Miyamoto, K et al. Exposure to pulsed low intensity ultrasound stimulates extracellular matrix metabolism of bovine intervertebral disc cells cultured in alginate beads. Spine. 2005 Nov 1; 30(21):2398-405.
The objective of this study was to determine whether pulsed low intensity ultrasound has effects on cell proliferation and extracellular matrix metabolism by bovine intervertebral disc cells.
The design of this study was an in vitro study on the effects of pulsed low intensity ultrasound on the cellular metabolism of bovine intervertebral disc cells.
Cells of the nucleus pulposus and inner and outer anulus fibrosus were enzymatically isolated from bovine coccygeal tissue and precultured in alginate beads for 14 days.
In the ultrasound group, pulsed low intensity ultrasound was administered to the culture for 20 minutes daily for an additional 20 days.
The control group was cultured in the same way but without administration of ultrasound.
Cell viability, DNA content, proteoglycan and collagen synthesis, and proteoglycan content at days 10 and 20 after the initiation of treatment were evaluated.
Characterization of newly synthesized collagen and proteoglycan was performed.
RESULTS:
- No significant differences in cell viability and DNA content were observed between the two groups.
- On day 20, proteoglycan synthesis was increased by the application of pulsed low intensity ultrasound in nucleus pulposus and inner and outer anulus fibrosus cells by 24-26%.
- The application of pulsed low intensity ultrasound increased proteoglycan content in alginate beads containing inner and outer anulus fibrosus cells.
- Collagen synthesis by cells isolated from all three zones of the intervertebral disc was increased by the application of pulsed low intensity ultrasound by 16-19%.
CONCLUSIONS:
The application of pulsed low intensity ultrasound stimulated extracellular matrix metabolism in intervertebral disc cells.
3. Warden SJ, et al. Low-intensity pulsed ultrasound accelerates and a nonsteroidal anti-inflammatory drug delays knee ligament healing. Am J Sports Med. 2006 Jul; 34 (7):1094-102.
Low-intensity pulsed ultrasound and nonsteroidal anti-inflammatory drugs are used to treat ligament injuries; however, their individual and combined effects are not established.
Sixty adult rats underwent bilateral transection of their knee medial collateral ligaments.
Animals were divided into 2 drug groups and treated 5 d/wk with celecoxib (5 mg/kg) mixed in a vehicle solution (NSAID group) or vehicle alone (VEH group).
One to 3 hours after drug administration, all animals were treated with unilateral active low-intensity pulsed ultrasound and contralateral inactive low-intensity pulsed ultrasound.
Equal numbers of animals from each drug group were mechanically tested at 2, 4, 8 and 12 weeks post injury.
RESULTS:
- After 2 weeks of intervention, ligaments treated with active low-intensity pulsed ultrasound were 34.2% stronger, 27.0% stiffer, and could absorb 54.4% more energy before failure than could ligaments treated with inactive low-intensity pulsed ultrasound.
- Ligaments from the NSAID group could absorb 33.3% less energy than could ligaments from the VEH group.
CONCLUSIONS:
Low-intensity pulsed ultrasound accelerated but did not improve ligament healing, whereas the nonsteroidal anti-inflammatory drug delayed but did not impair healing.
When used in combination, the beneficial low-intensity pulsed ultrasound effect was cancelled by the detrimental nonsteroidal anti-inflammatory drug effect.
Low-intensity pulsed ultrasound after ligament injury may facilitate earlier return to activity, whereas non-steroidal anti-inflammatory drugs may elevate early re-injury risk.
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