What type of splint is appropriate for a closed isolated mid‑shaft humerus fracture?

Midshaft Humerus Fracture Splint Type

For closed isolated mid-shaft humerus fractures, use either a coaptation splint (U-slab) or functional brace as initial immobilization—both achieve equivalent fracture alignment and clinical outcomes, with functional braces being easier to apply and better tolerated by patients.

Primary Recommendation

Based on the most recent high-quality evidence, initial immobilization type does not significantly impact fracture alignment or the need for unplanned surgical intervention 1. A 2025 study of 65 patients demonstrated that posterior long-arm splints, cuff and collar slings, and coaptation splints/functional braces all achieved similar improvements in coronal (8.3°) and sagittal (7.3°) alignment, with 86.2% of patients achieving acceptable alignment regardless of method 1.

Practical Application Algorithm

Choose your immobilization based on:

1. Functional brace/splint - Preferred option

   • Easier and faster to apply 2
   • Better patient tolerance 2
   • Can be applied immediately on day 1 as outpatient 3
   • Equivalent radiographic outcomes to coaptation splinting 4, 2
   • No significant difference in failure rates (28.2% vs 37.9%, p=0.322) 4

2. Coaptation splint (U-slab) - Alternative option

   • Traditional method with proven efficacy 5
   • Acts as dynamic splint to reduce deformity without causing distraction 5
   • More difficult to apply, especially when working alone 6
   • Requires modified technique for ease of application 6

3. Posterior long-arm splint or cuff/collar sling - Acceptable alternatives

   • Equivalent alignment outcomes 1
   • May be chosen based on resource availability and patient comfort 1

Key Clinical Considerations

Avoid these pitfalls:

• Do not use hyperflexion positioning—this can cause limb-threatening ischemia (evidence from pediatric literature applicable to positioning principles) 7
• Ensure splint allows full elbow range of motion and partial shoulder abduction 3
• Apply single layer of compressed cotton before splinting to prevent skin complications 3

Monitor for complications:

• Brace-related dermatitis occurs in 18% of nonoperatively managed patients 8
• Overall nonunion rate is 11% with nonoperative management (6% operative vs 18% nonoperative) 8
• Radial nerve palsy present at initial examination typically recovers spontaneously 5

Functional Brace Technique Specifics

When applying functional brace 3:

• Use 4 plaster strips of 12 layers, 5-7.5 cm wide (based on arm girth)
• Wrap arm with single layer compressed cotton first
• Apply lateral and medial strips, then anterior and posterior strips after molding
• Ensure strips permit full elbow ROM and partial shoulder abduction
• Prevent strip adherence except at proximal end
• Weekly tightening with fresh bandage layers over existing brace
• Place in loose collar and cuff sling intermittently, allowing active elbow motion and pendular shoulder movement

Expected Outcomes

With appropriate immobilization 3, 8:

• Union occurs in 98.5% of cases at average 10.3 weeks (range 6-16 weeks)
• 87.5% of radial nerve palsies recover
• Functional recovery relatively rapid in patients <35 years
• At 3 months: 43.9% excellent, 42.4% good, 9.1% fair, 4.6% poor results

The choice between coaptation splint and functional brace should prioritize ease of application and patient comfort, as both achieve equivalent clinical outcomes 4, 2, 1.