A preliminary study suggests that high-resolution computed tomography (CT) modeling allows surgeons to custom-design acrylic implants prior to reconstructive surgery for patients with severe defects in their faces and eye cavities. Such implants appear to offer excellent aesthetic results and are well tolerated over the long term, according to a report in the November/December issue of Archives of Facial Plastic Surgery, one of the JAMA/Archives journals.
Severe facial and eye cavity abnormalities may be present at birth or can occur following facial trauma or another medical procedure, such as the removal of a tumor, according to background information in the article. Surgery to correct such defects aims to restore anatomical integrity, to increase the function of the eyelids and face and to improve a patient's appearance by inserting an implant made either of the individual's own bone and tissue or synthetic materials. Typically, use of these implants, which are shaped during surgery, has failed to recreate ideal three-dimensional contours in the face. Designing synthetic implants beforehand may improve precision and contours, but concerns have been raised about the long-term implant stability and risk of infection associated with plastics and other non-organic materials.
Michael J. Groth, M.D., Jules Stein Eye Institute, Los Angeles, and colleagues assessed long-term outcomes following the use of acrylic implants in nine patients with complex facial and eye cavity defects caused by facial trauma. The five men and four women were between the ages of 28 and 63 years, with an average age of 48.7. Between one month and 40 years had elapsed since their facial injuries, which included a boating accident, motor vehicle crashes, falls and a snowboarding accident. All patients had previously undergone reconstructive procedures.
For the current investigation, the patients underwent three-dimensional high-resolution CT scanning of the face and head. These data were used to create a stone mold, from which a customized implant made of polymethyl methacrylate (PMMA, commonly known as acrylic) was cast. The implant was surgically placed and fixed using screws.
During an average of 4.3 years of follow-up, none of the patients experienced significant complications, such as infection, extrusion (forcing out) or displacement of the implant. "In all of the patients, wound healing was uneventful, with antibiotics given perioperatively," the authors write. "All of the patients demonstrated long-term sustained improvement of facial deformities," including facial symmetry and eyelid function.
"Many types of implant materials have been used for reconstructive orbitofacial surgery," they continue. "Autogenous [from the patient's body] materials such as bone grafts provide many advantages, including excellent biocompatibility and low infection and extrusion rates. However, these materials have pertinent limitations, such as the potential for a prolonged operative procedure, limited supply, significant resorption, donor site morbidity and minimal malleability and customization." Surgeons have been using materials such as PMMA to make implants for more than 45 years, and designing them beforehand offers even more advantages, including precision and improved function, they conclude.
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