by Michelle Rizzo

Last Updated: 2007-09-14 18:12:23 -0400 (Reuters Health)

NEW YORK (Reuters Health) – Hip and knee arthroplasty are rarely performed in patients older than 100 years, according to a study published in the August issue of Arthritis and Rheumatism. However, these patients should not be denied the option of this surgery.

Dr. Eswar Krishnan, of the University of Pittsburgh, Pennsylvania, and colleagues point out that, from a musculoskeletal specialist’s perspective, osteoarthritis and osteoporotic hip fracture are "two major causes of disability among the older age group."

The researchers examined the epidemiology and mortality outcomes of arthroplasty among centenarians. They used data from the Health-care Cost and Utilization Project Nationwide Inpatient Sample for the years 1993 through 2002. Nonagenarians were used as a comparison group.

The team adjusted for differences in the prevalence of congestive heart failure; neurologic diseases, such as dementia and stroke; renal and hepatic diseases, obesity and other risk factor. They used Cox regression models to assess mortality outcomes following arthroplasty.

A total of 679 hip arthroplasties were identified among centenarians, compared with 33,975 among nonagenarians. There were only 7 knee arthroplasties among centenarians, and 2,050 among nonagenarians. Eighty-three percent of centenarians who underwent arthroplasties were women. Hip fractures were responsible for 94% of non-elective hip arthroplasties among nonagenarians and centenarians.

The overall in-hospital mortality rates for centenarians and nonagenarians were 6.1 and 4.5 deaths per person-year of hospitalization, respectively. Results of multivariable Cox regression models limited to hospitalizations for hip arthroplasties alone revealed that centenarians had a higher mortality risk than nonagenarians who underwent a similar procedure (hazard ratio 1.45).

Hospitalization for hip arthroplasty among those over the age of 100 was associated with a lower risk of death when the analyses were performed using records of all centenarians. The adjusted HR was 0.85 for hip arthroplasty hospitalizations compared with all other causes of hospitalizations combined.

"The patients who get joint replacement do well in the short term," Dr. Krishnan said in an interview with Reuters Health.

"They die less frequently in the post-operative period than comparable patients admitted to the hospital for other reasons," he said. "The reason for this good prognosis is that the patients are highly selected for joint replacements."

"Joint replacements for centenarians are likely to be more frequent in the future, when selectively performed joint replacements can improve functional status of many of the elderly patients," Dr. Krishnan explained.

These findings suggest that joint replacements should not be denied to centenarians because of short-term post-operative life expectancy estimates, the researchers conclude.

Arthritis Rheum 2007;57:1038-1042.