How should a humeral midshaft non‑union be managed in a patient who has previously undergone a reverse total shoulder arthroplasty?

Management of Humeral Midshaft Non-Union After Reverse Total Shoulder Arthroplasty

Perform open reduction and internal fixation using compression plating with at least 6-8 cortical points of fixation above and below the non-union site, combined with autogenous bone grafting or bone graft substitutes, while protecting the radial nerve through neurolysis.

Surgical Approach and Technique

The management of humeral midshaft non-union in the setting of a previous reverse total shoulder arthroplasty requires revision fixation with specific technical considerations:

Core Surgical Principles

• Compression plating remains the gold standard for humeral shaft non-unions, achieving >90% union rates 1, 2, 3
• Perform radial nerve neurolysis at the time of revision surgery, as patients with prior nerve injury are at high risk for recurrent palsy 1
• Debride the non-union site thoroughly, resecting atrophic bone and drilling sclerotic areas to expose bleeding bone surfaces 3
• Consider shortening osteotomies to facilitate compression and apposition of healthy bone 1

Fixation Requirements

Critical fixation parameters based on successful versus failed outcomes 3:

• Achieve minimum 6-8 points of cortical fixation both proximal and distal to the non-union
• Use broad compression plates with interfragmentary lag screws when possible
• Failed fixations averaged only 2.7-3.0 cortical points of fixation—this is inadequate

Bone Grafting Strategy

You have two evidence-supported options 1, 2:

1. Autogenous cancellous bone graft from the iliac crest (traditional standard)
2. Bone graft substitutes alone without autograft—achieves 94% union rate and avoids donor site morbidity 1

The second option is particularly attractive given the revision setting and avoids additional surgical morbidity.

Special Considerations for Reverse Shoulder Arthroplasty Context

Prosthesis Preservation

• The existing reverse shoulder arthroplasty should be preserved if stable and well-functioning
• Focus fixation distal to the humeral stem, ensuring adequate bone stock for plate application
• The reverse prosthesis stem may actually provide some proximal stability if well-fixed

Alternative: Revision to Long-Stem Prosthesis

If the non-union involves bone loss near the prosthesis or the implant is loose, consider revision to a long-stem reverse shoulder arthroplasty that bypasses the non-union site 4. This is reserved for:

• Poor bone quality precluding stable fixation
• Significant bone loss at the non-union site
• Concurrent prosthetic loosening
• Elderly patients with low functional demands

However, this represents a salvage option rather than first-line treatment in most cases.

Advanced Fixation Techniques

For particularly challenging cases with:

• Osteopenic bone
• Large bone defects
• Prior fixation failure

Consider 2, 5:

• Locked compression plates for improved purchase in poor bone
• Dual plating (90-90 configuration) for enhanced stability
• Cortical allograft struts as supplemental fixation
• Intramedullary fibular strut grafts for additional structural support 6

Expected Outcomes and Timeline

• Union rate: 90-94% with proper technique 1, 2
• Mean time to union: 5-6 months 1, 3
• Repeat surgery rate: approximately 10-15% may require additional procedures

Critical Pitfalls to Avoid

1. Inadequate fixation: The most common cause of failure is insufficient cortical purchase (<6 points per side) 3
2. Failure to bone graft: Only 55% of unsuccessful platings included bone grafting—this is a critical omission 3
3. Ignoring radial nerve: Patients with prior nerve injury have high recurrence risk; always perform neurolysis 1
4. Inadequate debridement: Leaving sclerotic, avascular bone at the non-union site prevents healing 3

Postoperative Management

• Immobilization until early callus formation (typically 6-8 weeks)
• Progressive range of motion as healing progresses
• Serial radiographs every 6-8 weeks to document progressive healing
• Consider bone stimulation adjuncts if healing plateaus

The presence of the reverse shoulder arthroplasty complicates but does not preclude successful non-union treatment using established compression plating principles with meticulous attention to fixation adequacy and biological augmentation.