Patients aged 55 and younger were found to have worse pain, function, and quality of life (QOL) following total knee arthroplasty (TKA) compared to patients 75 years and older, according to a study presented at the 2023 AAOS Annual Meeting that looked at age-related differences in patient outcomes following TKA.
TKAs are one of the most performed surgical procedures in the United States, with the number of procedures expected to reach 7.4 million by 2030. While mean age for patients undergoing TKA is 67.2 years, a growing number of younger and more active patients are undergoing TKA.
“There was controversy in the existing literature examining knee replacement outcomes by age as some studies concluded young patients do better, other studies showed they do worse and then there were studies saying there was no difference based on age,” said lead author David Ayers, MD, FAAOS, orthopedic surgeon, University of Massachusetts Chan Medical School. “These studies included relatively small sample sizes and different types of methodologies, so we wanted to improve upon our base knowledge by analyzing a large data sample.”
The team used data from the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR) consortium, which is managed by Ayers at the University of Massachusetts Department of Orthopedics and Physical Rehabilitation. This consortium includes over 235 surgeons from hospitals across the country, providing a representative sample of national data.
The study, “Age-Related Differences in Pain, Function and Quality of Life Following Primary Total Knee Arthroplasty,” analyzed 11,602 patients who underwent a unilateral (one knee) TKA. Patients were segmented into cohorts by age: less than 55, 55-64, 65-74, and 75 years and older. The team collected the following patient information prior to surgery and at one-year postoperative:
- Detailed list of demographic data
- Comorbidity conditions using the Charlson Comorbidity Index
- Patient reported outcome measures (PROMs), including Knee Injury and Osteoarthritis Outcomes Scores (KOOSs) to determine their levels of pain, function, and QOL
- A short-form health survey (SF-12) which provided a Physical Composite Score and Mental Composite Score to assess the overall physical, social and emotional status of the patient
The study found that prior to surgery, younger patients (aged 55 and younger) reported worse pain, function, and QOL compared to older patients, especially those 75 years and older. At 1 year after TKA, younger patients still reported slightly worse pain, function, and QOL, but better function scores than patients older than 75.
“There’s a misnomer that patients under 55 who need a knee replacement are athletes or physically active individuals who have been exercising all their life but had a previous injury which caused osteoarthritis (OA),” said Ayers. “Instead, we found that overall, this group had a higher incidence of obesity (BMI>35), medical comorbidities, and were more likely to be current smokers. These factors and any previous injuries to the knee can result in arthritis, which can be significant enough to lead to TKA.”
Despite the difference in pain and QOL scores between the age groups, the study showed that all 4 groups benefited from the surgery greatly and experienced major improvements in pain, function, and QOL.
“Because of the successful nature of TKAs and with improved anesthetic techniques and rapid recovery protocols, age does not always correlate to being an optimal candidate for TKA, as it has more to do with a patient’s medical fitness level,” said Ayers. “If a patient is in good health, they can undergo the surgery. Based on our findings, orthopedic surgeons can recommend TKA as an appropriate and life-changing operation for people with advanced arthritis who do not respond to conservative care, even those over 75 years of age.”
To further guide surgeons and patients through the decision-making process, the research team used a multivariate regression analysis and found that age was a predictive factor for a patient’s postoperative pain score at 1 year. These data help them know what to expect in terms of pain at 1 year and set realistic expectations.
The team is currently testing a predictive algorithm that will provide patients an analysis of their expected pain, function, and QOL scores 1 year after surgery.
