What is the recommended treatment for implant impingement post fixation?

Treatment of Implant Impingement Post Fixation

The primary treatment for implant impingement post fixation is removal of the offending implant as soon as bony union or ligamentous healing is achieved, as hardware-induced impingement is associated with poorer functional outcomes and progressive tissue damage that cannot be resolved while the implant remains in situ. 1

Immediate Assessment and Decision-Making

When implant impingement is suspected post-fixation, evaluate for:

• Pain characteristics: Persistent pain without neurological symptoms is the typical presentation, occurring months to years after the initial procedure 2
• Functional impairment: Assess range of motion limitations and activity-related symptoms, as impingement causes measurably worse functional scores compared to non-impinged patients 1
• Imaging confirmation: Use dynamic musculoskeletal sonography or advanced imaging to document the relationship between hardware and adjacent structures, including evidence of bony erosion, soft tissue damage, or rotator cuff lesions 1

Treatment Algorithm Based on Severity

For Symptomatic Impingement with Tissue Damage

Remove the implant once adequate healing has occurred - this is the only definitive solution for hardware-induced impingement 1. The timing depends on:

• Fracture fixation cases: Remove hardware as soon as bony consolidation is confirmed radiographically 1
• Ligamentous injuries: Remove hardware once ligamentous healing is achieved, typically allowing sufficient time for stability 1
• Progressive damage: In cases showing rotator cuff lesions (occurring in 15% of impingement cases) or significant bony erosion (occurring in 50% of hook plate cases), prioritize earlier removal after minimum healing requirements are met 1

For Adjacent Segment Impingement

Extend the fusion to include the affected adjacent segment when spinal rods cause impingement on adjacent structures 2. This addresses:

• Rods extending beyond intended fusion levels that abut adjacent structures 2
• Dynamic impingement that worsens with spine extension or twisting movements 2
• Back pain persisting 6+ years after initial procedure without neurological deficits 2

Surgical Principles to Prevent Impingement

While treating existing impingement requires hardware removal, understanding prevention principles guides timing and approach:

• Correct component positioning: Maintain optimal combined anteversion and head-neck ratios to maximize impingement-free range of motion 3
• Adequate spacing: Ensure implants are not abutting adjacent structures at the time of initial placement, accounting for dynamic motion 2
• Restoration of anatomy: Restore proper offset and length to avoid osseous impingement 3

Critical Timing Considerations

Do not delay implant removal once impingement is confirmed and healing is adequate, as:

• Functional scores progressively worsen with continued impingement 1
• Tissue damage (rotator cuff tears, bony erosion) accumulates over time 1
• Pain and functional limitations persist until hardware is removed 1, 2

Common Pitfalls to Avoid

• Avoiding removal despite symptoms: The only solution for hardware-induced impingement is implant removal; conservative management will not resolve the mechanical problem 1
• Premature removal: Ensure adequate bony consolidation or ligamentous healing before removal to prevent loss of fixation 1
• Ignoring dynamic factors: Check for impingement through full range of motion, as adjacent structures may move closer to hardware during extension or rotation 2
• Underestimating tissue damage: Perform thorough imaging assessment, as 37.5% of impingement cases develop associated soft tissue lesions requiring additional intervention 1