Younger patients seeking TKR have more surgical complications than older patients

About one-fourth of patients were less than 60 years old: 22.7% were aged 50 to 59 years and 3.3% were younger than 50 years. The younger patients had more severe pain and worse physical function compared with patients 60 years or older, and were more likely to rate their knee symptoms as "unacceptable." In all age groups, more than 92% of patients said they were "definitely willing" to undergo TKA.

Expected outcomes of TKA also differed by age. Patients under 60 were more likely to say that improved ability to exercise and participate in sports was a "very important" outcome of TKA. In contrast, older patients were more likely to cite less-demanding outcomes, such as going up and down stairs and being able to straighten the leg.

Patients in the younger age groups had higher rates of severe obesity and smoking. Obesity is a key risk factor for osteoarthritis, while smoking increases the risk of complications following TKA surgery.

After evaluation, orthopaedic surgeons recommended TKA for 73.6% of patients overall. That figure increased from 52.2%for patients under 50 years, to 71.0 % for those 50 to 59 years old and 75.4% for those 60 years or older.

However, the effects of age were lessened after adjustment for other factors. In particular, surgeons were more likely to recommend TKA for patients with greater need, based on pain scores and ability to cope with symptoms, and in those with greater willingness to undergo the procedure.

However, knee replacement surgeons were less likely to recommended surgery for patients with more-demanding expectations, such as returning to sports or other vigorous activities. Consistent with the increased complication risk due to smoking, orthopedic surgeons were less likely to recommend TKA for patients who smoked.

Thus when all TKA appropriateness criteria were taken into account, "patient age was not associated with surgeons' TKA recommendations." At a time when TKA rates are rising fastest in patients less than 60 years old, "Incorporation of TKA appropriateness criteria into TKA decision-making may facilitate consideration of TKA benefits and risks in a growing population of young, obese individuals with knee OA," the researchers write.

Dr. Hawker adds: "Whether the short- and longer-term risks of TKA are outweighed by the benefits is unclear and warrants additional research."