Properly managing irradiated patients undergoing THA helps avoid complications
Fixation failure rates for cemented, cementless implants were high for irradiation doses >500 CGy.
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It is uncommon for total joint replacement surgeons to deal with cancers in their patients, but occasionally they may need to perform total hip arthroplasty in those who have been irradiated around the pelvis for gynecologic, prostate or colorectal cancer.
The important question is: To what extent has the radiation affected acetabular bone? Aaron G. Rosenberg, MD, FACS, said. Radiation can have severe effects depending on the dosage not only to the bone, but also to soft tissue.
Contact oncologist
He suggested first contacting the patients oncologist to see the extent of radiation exposure the patient had.
Rosenberg discussed these and other guidelines for performing total hip arthroplasty (THA) after pelvic irradiation during the Current Concepts in Joint Replacement winter meeting.
Doses greater than 500 centigray units (CGy) are most detrimental to bone quality and can compromise fixation of both cemented and cementless THA implants.
Distributing the stress
Surgeons should typically be prepared to supplement the acetabular fixation.
You need to treat the acetabulum like it is a tumor. Anti-protrusio devices are necessary to distribute stress and the classic technique of Harrington, to use threaded pins and supplemental cement in the cancerous bone to re-establish mechanical continuity, is a useful technique, Rosenberg said.
For better mechanical support, he discussed using a flange or tri-cage on top of that to further distribute stresses or implanting prostheses made of newer materials that promote bone ingrowth, like Trabecular Metal acetabular components (Zimmer).
Rosenberg recommended doing workups for patients based on age, treating lesions in anyone younger than 40 years-old as primary tumors, unless proven otherwise.
When in doubt, Rosenberg said, refer the patient out.
For more information:
- Aaron G. Rosenberg, MD, FACS, is professor of surgery, Rush Medical College. He can be reached at 1725 W. Harrison Ave., #1063, Chicago, IL 60612; 312-243-4244; e-mail: aarongbone@aol.com. He has consulting, teaching/speaking, board membership relationships with, holds intellectual property rights from and is an independent contractor for Zimmer Inc.
Reference:
- Rosenberg AG. The radiated hip: An increasing prevalence #32. Presented at the 24th Annual Current Concepts in Joint Replacement Winter Meeting. Dec. 12-15, 2007. Orlando, Fla.