FRIDAY, May 23 (HealthDay News) -- Obese patients are at increased risk for infection and dislocation following revision (second) hip replacement surgery, according to a study by researchers at Geneva University Hospitals in Switzerland.

They evaluated the impact of obesity on the incidence of serious complications after revision total hip arthroplasty (THA) in 114 women and 90 men, mean age 71.6, over a period of up to five years. The researchers also evaluated whether functional improvement, pain and satisfaction differed between obese patients and healthy-weight patients.

The findings revealed a strong correlation between obesity and high rates of adverse events, as well as lower functional gains and more persistent pain, following revision THA.

Overall, 20 complications occurred in 17 (33 percent) of the 52 obese patients, compared with 18 complications in 13 (9 percent) of the 152 non-obese patients. Obese patients (body-mass index of 30 or more) had four times more surgical site infections and 3.5 times more dislocations than non-obese patients.

The risk of one or more adverse events increased with rising BMI. Patients with a BMI of between 30 and 34.9 were 4.5 times more likely than normal weight patients to suffer problems, while those with a BMI of 35 or more were 10.5 times more likely to experience complications.

After five years, obese patients had moderately lower functional improvements and higher levels of routine hip pain.

The study was published in the May issue of Arthritis Care & Research.

"Surgeons, patients and referring physicians should be aware of an increased risk in this [obese] patient group," lead author Dr. Anne Lubbeke said in a prepared statement. "Further studies are necessary to evaluate whether changes in medical preparation, surgical technique, and implant choice can help reduce the adverse event rate in obese patients undergoing revision THA."

More information

The American Academy of Orthopaedic Surgeons has more about hip replacement.