What splint is preferred for a lateral tibial plateau fracture with a 5.5 mm depressed fragment?

Hinged Knee Brace or Knee Immobilizer

For a lateral tibial plateau fracture with 5.5 mm depression, initial immobilization should be achieved with a hinged knee brace or knee immobilizer, followed by urgent orthopedic consultation for definitive surgical management, as this degree of articular depression (>2-3 mm) requires operative intervention to prevent post-traumatic arthritis and restore joint congruity.

Rationale for Splinting Approach

Why This Fracture Requires Surgical Management

A 5.5 mm depressed fragment in a lateral tibial plateau fracture significantly exceeds the threshold for acceptable non-operative management. While the provided evidence focuses primarily on surgical techniques rather than initial splinting, the clinical context is clear:

• Articular depression >2-3 mm is generally considered an indication for surgical reduction to restore joint congruity and prevent long-term degenerative changes
• Recent research 1 demonstrates that even depressions >10 mm can be successfully managed surgically with good functional outcomes, with mean preoperative depression of 14.7 mm improving to 1.1 mm at one year

Appropriate Initial Immobilization

Hinged knee brace is the preferred option because:

• Allows controlled range of motion once swelling subsides
• Provides adequate stability while preventing further displacement
• Facilitates early mobilization protocols post-operatively
• More comfortable than rigid immobilization for the pre-operative period

Knee immobilizer (rigid splint) is an acceptable alternative if:

• Significant swelling is present
• Patient comfort requires complete immobilization initially
• Transport to definitive surgical care is delayed

What to Avoid

• Simple elastic bandages: Insufficient stability for displaced fractures
• Long leg cast: Unnecessarily restrictive and may complicate surgical planning
• Delayed immobilization: Risk of further articular damage

Clinical Pathway

1. Immediate: Apply hinged knee brace or knee immobilizer in extension
2. Within 24-48 hours: Obtain CT imaging to characterize fracture pattern and plan surgical approach 2
3. Surgical timing: Early definitive fixation within first 24 hours when patient is stable reduces complications 3
4. Post-operative: Transition to hinged brace allowing controlled motion as per surgeon protocol

Key Surgical Considerations (For Context)

The 5.5 mm depression will require:

• Open reduction and internal fixation
• Possible subchondral support (raft technique with cannulated screws 1)
• Bone grafting or substitute to fill void after elevation
• Plate fixation to maintain reduction

The splint is merely a temporizing measure—definitive treatment is surgical, and the immobilization device should facilitate rather than delay this pathway.