What is the step-by-step procedure for treating a fracture of the proximal humerus using multilocking (internal fixation device) nailing?

Multilocking Nailing Procedure for Proximal Humerus Fracture

The multilocking intramedullary nailing technique is an effective surgical option for treating proximal humerus fractures, providing stable fixation that allows early mobilization and improved functional outcomes. 1

Preoperative Assessment and Planning

• CT scan is the preferred imaging modality for detailed evaluation of fracture pattern, as it provides superior delineation of fracture lines compared to plain radiographs 2
• Three-dimensional volume-rendered CT images help better characterize fracture patterns and humeral neck angulation, which can affect functional outcomes 2
• Consider associated rotator cuff tears, which occur in up to 40% of humeral head fractures 2

Surgical Approach Options

Antegrade Approach (via shoulder)

• Position patient in beach chair position with affected arm freely movable
• Make an anterior acromial approach to expose the rotator cuff 3
• Create a small longitudinal incision in the rotator cuff to access the humeral head 1
• Identify the correct nail entry point at the apex of the humeral head, slightly medial to the greater tuberosity 3

Retrograde Approach (alternative)

• Position patient supine or lateral with elbow flexed 90°
• Entry point is through the olecranon fossa
• May offer faster rehabilitation in some cases 4
• Preferred when possible to avoid rotator cuff damage 5

Step-by-Step Procedure

1. Patient Positioning and Preparation

   • Position patient according to chosen approach (antegrade or retrograde)
   • Prepare and drape the entire upper extremity to allow manipulation during reduction 3

2. Fracture Reduction

   • Perform indirect reduction techniques to achieve anatomical alignment 3
   • Use image intensifier to confirm reduction quality
   • Temporary K-wire fixation may be used to maintain reduction 3

3. Entry Point Creation

   • For antegrade approach: create entry portal at the apex of the humeral head
   • Use awl to open the cortex, followed by entry reamer 1
   • Avoid damaging the articular surface of the humeral head 3

4. Guide Wire Insertion

   • Insert guide wire through entry point across the fracture site
   • Confirm position with fluoroscopy in multiple planes 3

5. Reaming

   • Perform sequential reaming over the guide wire
   • Ream 1mm larger than the selected nail diameter 1
   • Careful reaming helps prevent iatrogenic comminution 5

6. Nail Insertion

   • Mount the selected multilocking nail on the insertion handle
   • Insert nail over guide wire with gentle rotation, avoiding excessive force 3
   • Ensure proper depth - the proximal end should be slightly recessed below the articular surface to prevent impingement 5

7. Proximal Locking

   • Use the targeting device for proximal locking screws
   • Insert multiple locking screws in different planes for enhanced stability
   • For proximal fractures, consider additional screws into the humeral head 3

8. Distal Locking

   • Perform distal locking under fluoroscopic guidance
   • For antegrade approach: anterior-to-posterior locking is recommended to minimize radial nerve injury risk 5
   • For retrograde approach: lateral-to-medial locking is typically used 4

9. Final Assessment

   • Confirm nail and screw positions with fluoroscopy in multiple planes
   • Verify stability of the construct
   • Ensure no intra-articular penetration of hardware 3

10. Wound Closure

    • Repair the rotator cuff with absorbable sutures (for antegrade approach)
    • Close the wound in layers 3
    • Apply sterile dressing and arm sling

Postoperative Management

• Use arm sling for 7-10 days 3
• Begin active and passive shoulder exercises on day 1 with limitations:
  • Limit abduction to 60° for first 2 weeks
  • Increase to 90° for weeks 2-4
  • Unrestricted active mobilization after 4 weeks 3
• Radiographic follow-up at 2,6, and 12 weeks to assess healing 3
• Full weight bearing and sports activities typically after 3 months 3

Technical Pearls and Pitfalls

• Rotator cuff management: Careful repair of the rotator cuff is essential with antegrade approach to prevent postoperative pain and dysfunction 1
• Entry point selection: Improper entry point can lead to malreduction or iatrogenic fracture 5
• Nail size: Select appropriate nail diameter to prevent iatrogenic fracture during insertion 5
• Distal locking: When using antegrade approach, perform distal locking from anterior aspect to reduce risk of radial nerve injury 5
• Nail depth: Ensure the nail is inserted to proper depth to prevent impingement or penetration into the joint 5
• Fracture reduction: Anatomic reduction is critical before nail insertion to prevent malunion 3

Outcomes and Complications

• Most fractures heal with good anatomical position (>80%) 5
• Potential complications include:
  • Rotator cuff damage (with antegrade approach)
  • Radial nerve injury during distal locking (4 times more common with lateral approach) 5
  • Nail prominence into joint
  • Screw loosening
  • Nonunion (rare with proper technique) 5