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Comparing Hip Replacements with and without Special Coating

Hydroxyapatite is a calcium coating on joint replacement parts. It's used to increase the amount of bone-to-implant surface contact. Bone-to-implant contact is important. The more bone that fills in around a joint implant, the more secure the fit.

Researchers in Korea are testing the results of this coating in hip joint replacements. They studied 50 patients who had both hips replaced, one at a time. In all patients one implant had the coating, the other didn't. Using implants with and without this special coating in the same patient makes comparisons easier. The hips are the same in terms of the patient's gender, age, weight,health, bone quality, and activity level.

Results were measured for each patient's pain levels, function, changes in the bone, and implant loosening. At the end of the study the authors had no preference for one implant over another. All measures used had similar or equal results.

The authors conclude that hydroxyapatite coating on joint replacements doesn't seem to make any difference. Results are no better and no worse. They think the reasons for this are better surgical technique and improved implant design. Newer implants get a close fit inside the bone, so the special coating isn't necessary for a better fit.

References: Young-Hoo Kim, MD, et al. Comparison of Porous-Coated Titanium Femoral Stems with and without Hydroxyapatite Coating. In The Journal of Bone and Joint Surgery. September 2003. Vol. 85-A. No. 9. Pp. 1682-1688.

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