Implant migration

Last revised by Joachim Feger on 10 Jan 2022

Implant migration or hardware migration refers to the displacement of an implant or component away from its designated position and is associated with hardware failure and loosening. Examples of implant migration include screw break out or screw back out, cage extrusion, inlay extrusion, choledochal stent migration and intrapelvic cup migration.

The frequency of implant and hardware migration various significantly with the type of implant.

Predisposing factors for implant migration include 1-3:

  • implant malposition
  • imbalance of tissue tension
  • improper anchorage or suboptimal implant design

Clinical signs and symptoms depend on the type and location of the implant as well as the associated complications and might range from absence to severe pain and/or shock.

Complications of implant migration highly depend on the implant and its location and include 4:

  • hemorrhage
  • neurovascular injury
  • thrombosis or embolism
  • adjacent organ injury

Implant migration can be caused by altered local biomechanics including 2,5:

  • hardware failure
  • septic and/or aseptic loosening
  • tumor recurrence

Plain radiographs are the first-line imaging modality for assessing implanted hardware and detecting deviations from its expected position 5. Serial radiographs can help in the differentiation from primary implant malposition.

CT can accurately characterize implant position in various locations also with respect to the adjacent structures. It can also delineate associated complications 2.

MRI can localize and evaluate non-metallic implants and associated complications.

The radiological report should include a description of the following:

  • implant position  
  • associated complications if present
    • hardware failure
    • neurovascular injury
    • associated organ injury

Management depends on the presence and risk of further complications and includes watchful waiting, removal or revision1.

The main differential diagnosis of implant migration include the following 1:

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