Outcome After Total Knee Arthroplasty Clinical Trial
Official title:
The Association Between Pre-operative Pain Psychology and Hypersensitivity With Poor Functional Outcome After Knee Replacement
To explore whether there are factors that help us to understand why some patient outcomes are
not successful and identify prediction factors for progression. Assess central pain
sensitisation and psychology pre- and post-surgery with reliable tools that explore
prediction tools for good/poor progression and improve patient selection, patient preparation
and timing for surgery.
The aim of this project is to explore the effects of pre-surgical central pain sensitisation
on pain and function outcomes post-TKA. Central pain sensitisation will be assessed using
pressure algometry and the Pain Catastrophizing Scale will be used to explore pain
psychology. Functional outcomes post-TKA will be assessed using a commonly used scale for
patients' self-reported outcomes (Oxford Knee Score), visual analogue scale, a star excursion
balance test and four recommended patient performance-based tests.
Knee osteoarthritis (OA) is a major cause of disability around the world; it is the most
common chronic condition in primary care in the UK. By 2030 it is predicted to be the
greatest cause of disability in the general population. An effective end-stage treatment for
knee OA is knee-replacement surgery, which was first done in the 1970s and 1980s.
In England and Wales, the number of knee-replacement procedures recorded by the National
Joint Registry in 2013 was 91,703, which represents an increase of 0.9 % over 2012. The data
analysis by the National Joint Registry and the Office of National Statistics suggests that,
by 2030, primary TKAs will increase by 117% from the 2012 level. Subsequently, TKA revision
surgeries are expected to increase incrementally by 332%. There is a similar estimation of
demand for revision TKA surgeries in the United States; by 2030, they are expected to rise by
601% from the 2005 level. The United States estimation of primary TKA is for growth of 673%
from the 2005 level, which is similar to England and Wales's upper-limit projections.
Post-TKA, 75-85% of patients report satisfaction with surgery outcomes, while the remaining
15-25% are dissatisfied . Total knee arthroplasty's success has traditionally been evaluated
from the surgeon's perspective, e.g. the presence of surgical complications or implant
survival. This is gradually changing to involve the patient in measuring health outcomes and
decision-making processes. Patient-reported outcome measures (PROMs) have evolved to explore
patient perspectives by monitoring the quality of care in health organizations and conducting
clinical trial outcomes.
Worldwide National Joint Registry summarise the common indication for TKA revision are; 29.8%
due to aseptic loosening, 14.8% infection and 9.5% due to pain. Most prediction studies show
that pain and psychology pre-operation may predict poor outcomes post-TKA. A systematic
review by concludes that pain catastrophizing predicts chronic pain post-TKA. Pain
catastrophizing is defined as a construct that reflects anxious preoccupation with pain, an
inability to inhibit pain-related fears, amplification of the significance of pain vis-à-vis
health implications, and a sense of helplessness regarding pain.
Chronic post-surgery pain is significantly associated with preoperational central
sensitisation as in post-shoulder subacrominal decompression and hernia repair. Regarding
post-TKA, a study by Lundblad et al. (2008) concluded that the preoperational hand electrical
pain threshold significantly predicts pain outcomes one year post-TKA. The study explored the
association between chronic pain post-TKA and preoperation widespread pain sensitisation
using pressure algometry. Both study association without control the psychological confiding
factor. The correlation with Western Ontario and McMaster Universities Osteoarthritis Index
pain score (WOMAC) is questionable due to weakness of WOMAC with post TKA population such as
low sensitivity of WOMAC's stiffness subscale reduces the overall standardized response mean
and high ceiling effect Psychological pain thinking is assessed using the most widely used
measuring scale: Pain Catastrophizing Scale (PCS). PCS assesses pain thinking in three
dimensions: rumination ("I can't stop thinking about how much it hurts"), magnification ("I
worry that something serious may happen") and helplessness ("It's awful and I feel that it
overwhelms me").
The current study will investigate preoperational central sensitisation using pressure
algometry, in addition to the Pain Catastrophizing Scale (PCS), to explore psychological
factors. There may be some correlation between preoperational central sensitisation and
post-TKA outcomes such as pain and functional improvements.
To the best of our knowledge, no previous study has explored central sensitisation using
pressure algometry and the Pain Catastrophizing Scale and possible correlation with its
effects on pain and function recovery post-TKA. Pain and function can be accurately assessed
before and after TKA using visual analogue scale, Oxford Knee Score, balance and performance
functional tests. No previous study has correlated preoperational central sensitisation and
pain psychology post-TKA on the Oxford Knee Scale as commonly used patients' self-reported
outcome measures.
Thus, the study may explore accurate and objective prediction factors of post-total-knee
arthroplasty progression. Potentially, reliable outcome prediction could, however, improve
patient selection for surgery, as appropriate timing for surgery depends on patient symptoms
and efficient patient preparation for surgery if it is to be cost-effective. Accurate
preoperative prediction is crucial to minimize the potential for unrealistic expectations.
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