SAN DIEGO – It’s not unusual for total knee replacement patients to have arthritis in other joints, and it negatively impacts surgery outcomes, Toronto researchers have found.
In their study, 420 of 494 knee replacement patients (85%) reported problems in at least one other joint. Those with foot or ankle arthritis had a significantly reduced chance of achieving an MCID (Minimally Clinically Important Difference) on postoperative WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) pain and function scores (odds ratio pain 0.32, 95% confidence interval 0.185-0.544; OR function 0.53, 95% CI 0.303, 0.940).
Patients who reported neck problems also had reduced odds of achieving an MCID on physical function WOMAC scores (OR 0.37, 95% CI 0.183, 0.726).
"It’s not surprising that ankles and feet [were] significant. [They] impact activities for which lower-extremity joints are involved. How the upper extremities are associated here, in particular the neck, is unclear," said lead investigator Anthony Perruccio, Ph.D., an epidemiologist and research scientist at the Toronto Western Research Institute.
Because patients with neck problems also saw less improvement in fatigue, anxiety, depression, and pain, there may also be a mental health component, he said.
Whatever the case, the lesson is to treat the whole patient, not just the knee. Referrals to other types of providers are appropriate, including physiotherapists and mental health counselors as needed, said Dr. Perruccio.
"There’s more than just the one joint that’s involved here. Outcomes could be improved if a more holistic approach to osteoarthritis management were considered," he said.
All 494 patients had primary, unilateral knee replacements secondary to osteoarthritis. Their mean age was 65, 65% were women, and almost half were obese.
The patients filled out several surveys before their operations, including WOMAC and other pain and function scales plus the Profile of Mood States (POMS) fatigue scale, the Knee injury and Osteoarthritis Outcome Score (KOOS) sports and recreation scale, and the Hospital Anxiety and Depression Scale (HADS). They also pointed out on a homunculus diagram which joints were causing trouble.
Almost half (46%) reported pain on most days in four or more joints in addition to their operative knee. The nonoperative knee was a problem for 57%, elbows/wrists/hands were problematic for 49%, ankles/feet for 36%, the back for 31%, shoulders for 29%, hips for 25%, and neck for 22%. Just 15% said only their operative knee was symptomatic.
A year after their operation, patients took the surveys again. Those with back problems tended to see less improvement in fatigue at 1 year. Those with ankle or foot arthritis – in addition to diminished returns on pain and function – also saw less improvement than others in depression and sports and recreation scores.
The congress was sponsored by the Osteoarthritis Research Society International. Dr. Perruccio said he had no relevant financial disclosures. The work was funded by the Canadian Institutes of Health Research.
* Correction, 10/21/11: The original headline of this story, "Knee Replacement Worsens Arthritis in Other Joints," misrepresented the findings of this study. The headline has been revised.