Knee replacement pain predicted by comorbidity

By Lynda Williams, Senior medwireNews Reporter

Research may help physicians give patients undergoing total knee arthroplasty (TKA) a realistic expectation of surgery outcome based on their overall physical and mental health, US researchers believe.

The likelihood of pain 2-5 years after primary or revision TKA was significantly influenced by a wide range of comorbidities including heart disease and depression, report Jasvinder Singh (University of Alabama, Birmingham) and David Lewallen (Mayo Clinic College of Medicine, Rochester, Minnesota).

"Research studies should examine whether preoperative and possibly postoperative optimization of management of these comorbidities can potentially reduce the risk of poor pain outcomes after TKA," they suggest in Rheumatology.

"With an increasing volume of TKA in the United States, a better understanding of risk factors for poor outcomes is critical to allow patients and surgeons to have realistic and appropriate expectations of TKA."

The team reviewed data from the Mayo Clinic Total Joint Registry for knee pain and function assessments of primary TKA patients 2 (n=7139) and 5 (n=4234) years after surgery. Records for revision TKA patients 2 (n=1533) and 5 (n=881) after surgery were also collated.

The majority (94%) of patients underwent TKA for knee osteoarthritis, while 4% had rheumatoid arthritis, and 2% other indications. Patient records were examined for diagnoses of heart disease, peripheral vascular disease, renal disease, chronic obstructive pulmonary disease, diabetes, connective tissue disease, anxiety, and depression.

Multivariate analysis showed that the likelihood of moderate-to-severe knee pain in primary TKA patients at the 2-year check up was significantly predicted by anxiety (odds ratio [OR]=1.4), after adjusting for age, gender, body mass index, underlying diagnosis, American Society of Anesthesiologist class, implant fixation, and distance from medical center.

At 5 years, pain in primary TKA patients was significantly predicted by heart disease (OR=1.7), depression (OR=1.7), and anxiety (OR=1.9).

For the revision TKA patients, connective tissue disease (OR=0.5) and depression (OR=1.8) were significant predictors of moderate-to-severe pain at 2 years, but no comorbidity predicted outcome at 5 years.

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