Predicting Adverse Events After Total Knee Replacement
What problem was studied?
When arthritis severely damages a joint or causes pain that is not relieved by medication and non-medication therapies, replacing the damaged joint with a prosthetic one can relieve pain and help restore function. The knee is the most commonly replaced joint, and although knee replacement is generally successful, like any surgery, it carries risks. Among the most serious potential problems are blood clots, infection, pneumonia, heart attacks and even death.
What was done in the study?
To identify factors that predict adverse outcomes in people undergoing total knee replacement, Arthritis Foundation-funded researcher Daniel Solomon, MD, MPH, of Brigham and Women’s Hospital in Boston and his colleagues studied Medicare beneficiaries in four U.S. states who had undergone the surgery during 2000. The researchers also surveyed orthopaedic surgery administrators from hospitals caring for those patients about a range of hospital characteristics. Relationships between these hospital characteristics, patient variables, and 90-day postoperative adverse events were analyzed using generalized estimating equations adjusting for hospital volume. They assessed these relationships in both low- and high-risk groups.
What were the study results?
Of the 9,073 patients studied, 327 (3.6 percent) experienced an adverse event related to total knee replacement. Analysis showed that hospital characteristics predicting those adverse events included the following:
- Low hospital volume – people were more likely to have adverse events if they had their surgery at a hospital performing fewer than 23 knee replacements on Medicare recipients each year.
- Absence of a perioperative patient education program.
- Fewer total knee replacements conducted in a dedicated orthopaedic surgery operating room, versus a general operating room.
Patient variables most closely related to adverse events were:
- being a man;
- being older than 70 years;
- having at least one health condition in addition to arthritis.
When all of the variables were accounted for, adverse events occurred in 2 percent of patients in the lowest risk category and in 7.4 percent of those in the highest risk category.
What is the relevance to people having or considering total knee replacement?
This index is preliminary; if it is validated in additional studies, it could be useful for the hospitals that perform total joint replacement as well as for the referring doctors and their patients, says Dr. Solomon. Knowing who is at highest risk of suffering complications as well as the hospital characteristics associated with complications from total knee replacement can help both doctors and patients in weighing the risks versus benefits of total joint replacement and can aid in making decisions regarding the best hospital for the procedure. The information can also help hospitals improve their surgical success rates and doctors identify patients who may need additional interventions to prevent complications of surgery.