One in three osteoarthritis patients have clinically significant fatigue immediately before total knee replacement but the proportion drops to just 8% a year later, Australian research shows.
Associate Professor Marlene Fransen, from the University of Sydney, and colleagues said that identifying and addressing early predictors of persistent fatigue has the potential to further improve patients’ quality of life after surgery.
Writing in Arthritis Care and Research, they said fatigue had been neglected in OA research, even though it was as common as in rheumatoid arthritis, where tiredness was well-recognised as a disabling symptom.
“Fatigue…has been associated with activity limitations, reduced physical activity, sleep problems, emotional stress and depression in people aged 65 years and older,” the research team wrote.
As part of the MARKER randomised study examining the impact of structured exercise programs and physiotherapy after TKR, patients used a 10 cm visual analogue scale to describe how much of a problem fatigue had been in the last week.
“Clinically-important fatigue (≥6.7/10) was reported by 34% of patients before surgery,” they said.
“This declined to 14%, 12% and 8% at six weeks, six months and 12 months after surgery, respectively.”
Lower knee extensor strength at baseline was associated with more fatigue at six months. Baseline knee pain, activity limitations, number of comorbidities and lack of energy were all strongly associated with fatigue at both six and 12 months after surgery.
Importantly, some factors identifiable at six weeks predicted greater fatigue at 12 months. Women and those with more comorbidities, depression and fatigue were at greater risk.
“As adequate knee extensor strength is essential for many activities of daily living, and functional performance is significantly related to quadriceps strength of both legs, it seems paramount that specific knee extensor strength training is necessary to reduce fatigue and optimise functional ability six months following surgery,” they said.
Poor self-reported psychological wellbeing was also a risk factor for persistent fatigue.
“In line with findings among patients with RA, treatment of fatigue among people with TKR will likely be enhanced by a multifaceted approach to rehabilitation that includes cognitive and behavioural dimensions,” they said.
A better understanding of fatigue and how it relates to joint pain, activity limitations, muscle fatigue and mental health has the potential to result in improved management strategies and quality of life after TKR, they concluded.