What is a Philadelphia Collar?
A Philadelphia collar is a semi-rigid cervical orthosis (neck brace) designed to restrict cervical spine movement by providing external support from the chin and occiput down to the upper thorax, commonly used in the management of suspected or confirmed cervical spine injuries.
Device Description and Design
The Philadelphia collar is a two-piece cervical immobilization device that wraps around the neck and is secured with Velcro straps. It extends from the mandible (chin) and occiput (back of skull) down to the upper chest and upper back, providing more coverage than soft collars but less rigidity than devices like halo vests 1.
Key Characteristics:
- Semi-rigid construction: Provides moderate restriction of neck movement
- Adjustable fit: Velcro straps allow for sizing adjustments
- Anterior and posterior components: Can be separated (anterior portion removable for procedures like intubation) 2
- Pressure distribution: Exerts contact pressure at the occiput, mandible, and chin 3
Clinical Applications
The Philadelphia collar has been used for:
- Acute cervical spine injury immobilization: Particularly C-2 and C-3 fractures 1, 4
- Post-operative stabilization: Following cervical spine surgery
- Conservative management: As an alternative to more invasive devices like halo vests in selected cases 1
Movement Restriction Capabilities
The Philadelphia collar significantly reduces cervical spine motion in multiple planes 5:
- Flexion: Reduced by approximately 12.5 degrees
- Extension: Reduced by approximately 0.9 degrees
- Lateral bending: Reduced by approximately 2 degrees
- Axial rotation: Reduced by approximately 4.7 degrees
However, it does not completely immobilize the cervical spine and allows residual movement 6.
Important Clinical Considerations
Complications with Prolonged Use:
The Philadelphia collar can cause significant complications, particularly after 48-72 hours of continuous use 7:
- Increased intracranial pressure: Mean increase of 4.69 mmHg 5
- Pressure ulcers: Particularly at contact points (occiput, mandible, chin) 3
- Respiratory compromise: Can reduce expiratory flow, though typically not clinically significant in healthy individuals 8
- Reduced mouth opening: Complicates airway management 2
Pressure Concerns:
The Philadelphia collar can exceed capillary closing pressure at contact points, especially when the patient is supine, increasing risk of skin breakdown 3. Pressures can exceed 100 mmHg with high strap tensions 9.
Critical Limitations
The evidence for cervical collar efficacy is surprisingly weak 5:
- No high-quality evidence demonstrates clinical benefit in preventing neurological injury
- May paradoxically increase subluxation at injury sites, particularly at craniocervical and cervicothoracic junctions 7
- The 2015 International Consensus on First Aid Science suggests against routine use by first aid providers (weak recommendation, very-low-quality evidence) 5
When to Remove:
- During airway management: The anterior portion should be removed to improve mouth opening and glottic visualization 2
- If complications develop: Particularly pressure ulcers or respiratory compromise
- Once cleared clinically/radiologically: Prolonged immobilization beyond necessity increases morbidity 7
Comparison to Other Devices
The Philadelphia collar provides intermediate immobilization:
- More restrictive than: Soft collars
- Less restrictive than: Vacuum splint collars, Miami-J collars (in some planes) 6, 10, or halo vests
- Similar efficacy to: Halo vest for C-2, C-3 fractures in selected patients (fusion success rate comparable) 1
Patient Comfort
Subjective comfort ratings place the Philadelphia collar in the middle range (3.00 out of 5.00) compared to other cervical orthoses 3. The open-design collars generally receive higher satisfaction scores 10.