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New joints may mean a green light for exercise

March 16, 2010 | 12:22 pm

Having joint replacement surgery doesn't always mean the end of exercising. Two new studies find that life after replacements and resurfacing can include physical activity — even the strenuous kind.

Idmnr7kfIn a study presented at the recent annual meeting of the American Academy of Orthopaedic Surgeons in New Orleans, researchers compared two groups of people who went through total knee replacement surgery at the Mayo Clinic. One group consisted of 218 men and women who took part in sports and activities not recommended by the Knee Society, including basketball, hockey and power lifting, that could lead to implant wear and failure. The other group, 317 people, was matched in gender and age, but the participants engaged in less strenuous recommended activities, such as ballroom dancing, stationary cycling and swimming. This group acted as a control.

About 7 1/2 years after surgery, researchers found few differences in how the groups fared. The sport group had a 10% greater risk of mechanical failure compared with the control group, but the control group had a 20% higher revision rate than the sport group for mechanical failures that included loosening, fracture or wear. The sport group also had slightly higher function scores compared with the control group.

"We hypothesized that high-impact activities would not increase the risk of implant failure, but we did not foresee that such activities might actually improve clinical results," said lead author Dr. Sebastian Parratte, a Mayo Clinic orthopedic surgeon, in a news release. "It is clear that more research is necessary to evaluate the short and long-term effect of high-impact activities on the durability and function of modern [knee] implants." In the other study, people who had hip resurfacing continued activity after surgery, although the level decreased somewhat. Researchers followed 138 people who had 152 hip resurfacing procedures, in which the hip ball is covered with a metal device but less bone is removed than in a hip replacement. Before surgery, patients took part in an average of 3.6 sports per person, while after surgery that number went down to 3.2.

Researchers found a substantial decrease in arduous sports such as tennis, jogging and soccer, and participants said they missed taking part in those activities. However, there was an increase in low-impact sports such as Nordic walking and weight training. Two years after surgery, 65% of study participants did sports for the same amount of time per week as before surgery, while 25% increased duration and 10% decreased it. At follow-up, 82% of participants felt no restrictions on their resurfaced hip during sports, while 16% did feel restricted (3% didn’t respond).

The study was published online March 11 in the American Journal of Sports Medicine.

— Jeannine Stein

People take part in Nordic walking. Photo credit: Los Angeles Times