Spinal Cord Injury Device
Precision weight-drop device for controlled spinal cord contusion injuries in mice, featuring adjustable drop heights (10-20 mm) and guided impact system for reproducible T9 vertebral injuries.
Louise Corscadden, PhD
Neuroscience · ConductScience
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The Spinal Cord Injury Device is a precision weight-drop contusion model for controlled spinal cord injury induction in mice. Based on the Allen weight-drop technique first established in 1911 and refined by Pajoohesh-Ganji and colleagues, this device delivers reproducible contusion injuries through a guided falling weight system. The device features a Teflon-coated stainless steel weight (1.85 g) that travels through a 25 cm hollow Teflon tube to impact a steel impounder positioned at the T9 vertebral level.
The system allows for two standardized injury severities: mild-to-moderate injuries using a 10 mm drop height and moderate-to-severe injuries using a 20 mm drop height. The steel impounder (3 cm height, 5 mm diameter) incorporates a 1.2 mm diameter needle for precise tissue penetration. A horizontal pin guidance system prevents weight bouncing on impact, ensuring consistent energy transfer. The weight is retrieved using a rod magnet after injury induction, facilitating sterile technique maintenance during surgical procedures.
How It Works
The device operates on controlled gravitational energy transfer through a guided weight-drop mechanism. A 1.85 g Teflon-coated stainless steel weight is positioned at a predetermined height (10 mm or 20 mm) within a 25 cm hollow Teflon tube. When released via removable pin withdrawal, the weight travels down the tube under gravitational acceleration, impacting the steel impounder positioned over the exposed T9 spinal cord segment.
The impounder features a 1.2 mm diameter needle that penetrates the spinal cord tissue, delivering precise mechanical trauma. A horizontal pin guidance system prevents the weight from bouncing upon impact, ensuring single-strike energy delivery and reproducible injury severity. The kinetic energy at impact varies with drop height: 10 mm drops produce mild-to-moderate contusions while 20 mm drops generate moderate-to-severe injuries. The Teflon tube construction minimizes friction during weight descent, maximizing energy transfer consistency.
Post-impact weight retrieval occurs via rod magnet, maintaining sterile conditions during the surgical procedure. The device's geometry ensures that injury forces are concentrated at the T9 level, the standard location for modeling human thoracic spinal cord injuries and associated paraplegia.
Features & Benefits
tube_length
- 25 cm
tube_diameter
- 6 mm
impounder_height
- 3 cm
impounder_diameter
- 5 mm
needle_length
- 1 cm
needle_diameter
- 1.2 mm
drop_height_mild_moderate
- 10 mm
drop_height_moderate_severe
- 20 mm
weight_mass
- 1.85 g
injury_location
- T9
Automation Level
- manual
Material
- Steel
- Teflon
- Stainless Steel
Species
- Mouse
Research Domain
- Addiction Research
- Behavioral Pharmacology
- Motor Function
- Neurodegeneration
- Neuroscience Models
- Pain Research
Weight
- 30.92 kg
Dimensions
- L: 1.18 mm
- W: 0.2 mm
- H: 28.8 mm
| Feature | This Product | Typical Alternative | Advantage |
|---|---|---|---|
| Weight Mass | 1.85 g Teflon-coated stainless steel | Weights often range from 2-10 g in other weight-drop models | Lighter weight reduces excessive tissue damage while maintaining sufficient impact energy for consistent contusions. |
| Drop Height Adjustment | Two standardized settings: 10 mm and 20 mm | Some models offer continuously variable heights | Standardized heights ensure reproducible injury severities that align with established literature protocols. |
| Guidance System | Horizontal pin prevents weight bouncing | Basic models may lack anti-bounce mechanisms | Single-impact delivery eliminates secondary trauma from weight bouncing, improving injury consistency. |
| Weight Retrieval | Rod magnet system for sterile removal | Manual removal or gravity-based systems | Maintains sterile surgical conditions and prevents contamination during multi-subject studies. |
| Construction Materials | Teflon and stainless steel components | All-metal construction in some devices | Teflon elements reduce friction and improve weight descent consistency while resisting chemical damage. |
This device combines the simplicity of gravitational weight-drop injury with precision engineering features including anti-bounce guidance, sterile retrieval, and standardized drop heights. The 1.85 g weight and Teflon-lined tube system provide consistent energy transfer for reproducible T9 spinal cord contusions in mouse models.
Practical Tips
Verify drop height measurements before each experimental session using precision measuring tools to ensure consistent injury severity.
Why: Small variations in drop height significantly affect impact energy and resulting injury characteristics.
Clean all components with 70% ethanol between subjects and inspect the Teflon tube for scratches or debris that could affect weight descent.
Why: Contamination or surface damage can alter weight trajectory and compromise injury reproducibility.
Ensure the mouse is properly anesthetized and positioned with the T9 vertebra directly aligned beneath the impounder needle before weight release.
Why: Precise anatomical positioning is critical for targeting the correct spinal cord segment and avoiding off-target injuries.
Always use the rod magnet to retrieve the weight rather than manual handling during surgical procedures.
Why: Magnetic retrieval maintains sterile conditions and prevents accidental needle stick injuries from the impounder.
Record the exact drop height, weight position, and impact timing for each subject to enable proper statistical analysis of injury parameters.
Why: Detailed documentation supports reproducibility assessment and enables correlation of injury parameters with functional outcomes.
If the weight does not descend smoothly, check for debris in the Teflon tube or damage to the weight's Teflon coating.
Why: Friction during descent alters impact velocity and can lead to inconsistent injury severity between subjects.
Test the magnet retrieval system before beginning surgical procedures to ensure proper magnetic strength and positioning.
Why: Functional retrieval system prevents delays during surgery that could compromise animal welfare or experimental timing.
Setup Guide
What’s in the Box
- Hollow Teflon tube (25 cm length, 6 mm diameter)
- Steel impounder with 1.2 mm needle
- Teflon-coated stainless steel weight (1.85 g)
- Horizontal guidance pin
- Removable support pin
- Rod magnet for weight retrieval
- Teflon base component
- Assembly instructions (typical)
- Calibration certificate (typical)
Warranty
ConductScience provides a standard one-year manufacturer warranty covering defects in materials and workmanship, with technical support for setup and operational guidance.
Compliance
References
Background reading relevant to this product:
What is the difference in injury severity between 10 mm and 20 mm drop heights?
The 10 mm drop height produces mild-to-moderate contusions while the 20 mm drop height generates moderate-to-severe injuries. The increased gravitational potential energy at 20 mm results in greater tissue damage and more pronounced functional deficits.
How is weight bouncing prevented to ensure single-impact injuries?
A horizontal pin guidance system attached to the impounder prevents the 1.85 g weight from bouncing upon impact, ensuring all kinetic energy is transferred in a single strike for consistent injury characteristics.
What anatomical level does this device target for spinal cord injuries?
The device is specifically designed for T9 vertebral level injuries, which corresponds to the standard anatomical location for modeling human thoracic spinal cord injuries and associated paraplegia.
How is sterile technique maintained during weight retrieval?
A rod magnet system allows for sterile retrieval of the Teflon-coated stainless steel weight without direct manual contact, maintaining aseptic conditions throughout the surgical procedure.
What materials are used to minimize friction during weight descent?
The hollow tube is constructed from Teflon and the weight features a Teflon coating to ensure friction-free descent and consistent energy transfer to the impact site.
How does this compare to electromagnetic or pneumatic injury devices?
This weight-drop system provides simpler operation without requiring electrical power or compressed air systems, while still delivering reproducible injury through gravitational energy that closely mimics traumatic injury mechanisms.
What maintenance is required between experimental subjects?
Components should be cleaned with appropriate disinfectants between subjects, and the weight position should be verified at the correct drop height. The magnet retrieval system should be tested for proper function.
Can the needle diameter be modified for different tissue penetration requirements?
The device features a fixed 1.2 mm diameter needle optimized for mouse spinal cord tissue. Modifications would require custom manufacturing and validation studies to ensure injury reproducibility.
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