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26-04-2012 | Surgery | Article

Key factors predict TKR surgery outcome

Abstract

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MedWire News: Pain and functional outcome after primary total knee replacement (TKR) are predicted by different clinical and demographic factors, UK study findings suggest.

But body mass index (BMI) was not a significant predictor for pain or functional outcome, say Andy Judge (University of Oxford) and co-authors.

"The findings are important to decision-making, as physicians often advise patients they are too old or obese to receive TKR," they write in Rheumatology.

"We can conclude that in relation to patient-reported outcomes of TKR, age and BMI should not be a barrier to surgery."

The team used the Oxford Knee Score (OKS) and other surveys to assess TKR outcome for 1991 patients, aged an average of 71.3 years, undergoing surgery between 2005 and 2008 at an orthopedics center in South-West London. Overall, 89.6% of the patients who completed the preoperative OKS returned the postoperative questionnaire 6 months later.

OKS results showed a general trend to improved pain and function following surgery, with 71.7% of patients achieving a patient acceptable symptom state (PASS) by follow-up.

Analysis showed that preoperative OKS was one of the strongest predictors for a postoperative OKS with regard to patient pain and function. Socioeconomic status was also a strong predictor for PASS, with patients living in deprived areas experiencing a poorer outcome than their less deprived counterparts.

Greater levels of postoperative pain were also predicted to a lesser extent by a diagnosis of osteoarthritis (versus rheumatoid arthritis), and higher preoperative measures for depression and anxiety.

By contrast, postoperative function was significantly poorer in women and older patients, although Judge et al note this effect size was small.

"Expectations of the patients may also play a role, where for example, what a young person wants to achieve in functional rehabilitation is different from an older person, for whom a lower attained functional score may be perfectly acceptable," they say.

Finding that just 14.6% of variation in total OKS outcome was predicted by age, gender, deprivation, preoperative OKS, and diagnosis, the team emphasizes the need to identify further markers for TKR outcome, such as comorbidity and surgical technique.

"It is possible that the way information on pre-operative pain/function, mental health and co-morbidities is measured is not detailed enough to capture variability in its relation to outcome," they admit.

By Lynda Williams

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