Why Anesthetic is Injected Under the Implant
Local anesthetic is injected beneath an implant during removal to dissect the implant from surrounding tissue through hydrodissection, which facilitates separation of adhesions and makes the removal procedure technically easier and less traumatic.
Mechanism and Rationale
The primary purpose of injecting anesthetic under an implant is hydrodissection - using fluid pressure to mechanically separate tissue planes. When local anesthetic solution is infiltrated beneath the implant, it:
- Creates a fluid plane that physically separates the implant from adherent surrounding tissue, making dissection easier and reducing the need for sharp or blunt dissection that could damage adjacent structures 1
- Reduces adhesions between the capsule and surrounding tissue that develop from prolonged presence of the implant 1
- Provides direct anesthesia to the tissue plane being manipulated, ensuring adequate pain control during the removal procedure 1
Additional Benefits
Beyond the mechanical dissection effect, the anesthetic solution provides:
- Hemostasis when epinephrine is included in the mixture, reducing bleeding during the procedure 1
- Reduced intraoperative pain through direct local anesthetic effect on the tissue being manipulated 1
- Easier visualization of tissue planes as the fluid expands the space between structures 1
Clinical Application
This technique is particularly valuable when:
- Removing implants that have been in place for extended periods, where fibrous adhesions are more likely to have formed 1
- The implant capsule is adherent to surrounding parenchyma or tissue, making blunt dissection difficult 1
- A mixture of Ringer's lactate with lidocaine and epinephrine is commonly used for this purpose 1
Important Caveat
While this hydrodissection technique facilitates removal, clinicians should be aware that it can be tedious in cases with significant adhesions, and the benefits must be weighed against the pitfalls of the technique 1.