What are the key considerations and techniques for successful radial head replacement surgery?

Radial Head Replacement: Key Technical Considerations and Surgical Techniques

Radial head replacement is indicated for unreconstructable comminuted radial head fractures, particularly when associated with ligamentous injuries or elbow instability, and should be performed through a Kocher interval approach with meticulous attention to implant sizing to prevent complications. 1, 2

Primary Indications for Radial Head Replacement

• Comminuted non-reconstructible radial head fractures (Mason III-IV) where robust fixation of fragments is not possible 1, 3
• Fracture-dislocations with concurrent ligamentous injuries, including terrible triad injuries and Essex-Lopresti injuries 1
• Complex elbow injuries involving radial head fractures with ligamentous ruptures with or without coronoid process fractures 4

Critical Preoperative Planning

Imaging Requirements

• Obtain high-resolution CT imaging to assess fracture pattern, fragment size, and associated injuries 1, 3
• Evaluate for concomitant injuries including medial/lateral collateral ligament disruption, coronoid fractures, and ulnar shaft fractures 1

Implant Selection Considerations

• Multiple implant designs are available (metallic monopolar, bipolar, pyrocarbon) without conclusive evidence supporting superiority of one design over another 3, 4
• Longer-stem implants and cemented bipolar endoprostheses may reduce revision rates and prevent stem loosening complications 1
• Uncemented, loose-fitting monopolar prostheses remain the most commonly used, with cementation reserved for cases where the implant appears unstable within the proximal radius 5

Surgical Technique: Step-by-Step Approach

Surgical Approach

• Use Kocher's interval in all cases - this provides optimal exposure while minimizing risk to the posterior interosseous nerve 1, 2
• Identify and protect the lateral collateral ligament complex during dissection to maintain elbow stability 1

Implant Positioning and Sizing

The most critical technical factor is accurate implant sizing - oversizing leads to osteolysis, undersizing causes instability. 2

• Measure the native radial head diameter using preoperative imaging or intraoperative assessment of fragments 2
• Position the prosthetic head at the anatomic level - typically 1-2mm proud of the coronoid tip to restore proper radiocapitellar contact 2, 3
• Ensure the stem sits securely without excessive reaming, as oversizing the shaft causes extensive osteolysis 2
• Verify implant stability by testing rotation and axial loading before closure 2

Assessment of Elbow Stability

• Test valgus and varus stability intraoperatively after implant placement 4
• Assess forearm rotation through full pronation and supination to ensure no impingement 2
• Verify radiocapitellar tracking throughout the arc of motion 3

Common Pitfalls and How to Avoid Them

Implant Sizing Errors

• Oversized head diameter causes capitellar wear, pain, and limited motion 2
• Oversized stem diameter leads to periprosthetic osteolysis and potential loosening 1, 2
• Solution: Use trial components and fluoroscopic confirmation before final implantation 2

Stem-Related Complications

• Periprosthetic lucencies or osteolysis occur in approximately 18% of cases but may not affect functional outcomes 1
• Stem loosening can occur with shorter stems - consider longer-stem designs for improved fixation 1
• Prosthesis disconnection or shaft fracture are rare but catastrophic complications requiring revision 2

Soft Tissue Management

• Repair all associated ligamentous injuries at the time of radial head replacement to prevent persistent instability 1
• Address coronoid fractures if present, as these contribute significantly to elbow instability 4

Postoperative Management Protocol

Immobilization

• Apply plaster splint from metacarpophalangeal joints to shoulder for 2-3 weeks postoperatively 1
• Early mobilization after splint removal is critical to prevent stiffness 2

Rehabilitation Timeline

• Weeks 0-3: Protected immobilization with splint 1
• Weeks 3-6: Progressive active range of motion exercises 2
• Months 2-6: Strengthening and functional restoration 2

Expected Outcomes and Complications

Functional Results at 1 Year

• Mean flexion-extension arc: 124-130° 1, 4
• Mean pronation: 74-80° 1, 4
• Mean supination: 72-86° 1, 4
• Mayo Elbow Performance Score: 88-92.5 points (good to excellent) 1, 2
• DASH score: 11.2 (minimal disability) 1

Reoperation Risk

Patients must be counseled that radial head replacement carries a 25% risk of reoperation, with 70% of reoperations occurring within the first year. 5

• Cumulative implant survival rate: 71% at long-term follow-up 5
• Peak risk period: Within 12 months of implantation 5
• Common reasons for removal: Persistent pain, stiffness, or implant-related complications 5

Long-Term Outcomes

• At minimum 8-year follow-up, patients report low disability (QuickDASH 13 ± 14) despite high reoperation rates 5
• Heterotopic ossification may develop but does not necessarily compromise functional outcomes 1
• Radiological signs of stem loosening do not necessarily correlate with poor functional outcomes 1

Key Technical Pearls

• Accurate implant sizing is the single most important factor for preventing complications 2
• Longer-stem cemented bipolar designs may offer advantages in reducing revision rates 1
• Kocher approach provides optimal exposure while protecting neurovascular structures 1, 2
• Address all associated injuries (ligaments, coronoid) at the time of radial head replacement 1, 4
• Early mobilization after brief immobilization optimizes functional recovery 1, 2