1. Assessing pain in patients undergoing joint replacement
Dr Vikki Wylde
Research Associate
Musculoskeletal Research Unit, University of Bristol

2. Outline Chronic pain definition Chronic post-surgical pain
Pain assessment methods
Clinician-administered tools
Patient-reported outcome measures
Quantitative Sensory Testing
Recent innovations in pain assessment methods

3. What is chronic pain?
International Association for the Study of Pain Definition:
“an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage”
Chronic pain: present for 3-6 months

4. Chronic pain and total knee replacement (TKR)
Osteoarthritis is leading cause of chronic pain in Europe
- Cited by 34% of people as cause of self-reported chronic pain1
Primary aim of joint replacement is to relieve chronic pain2
Some patients continue to experience chronic pain after joint replacement
1Breivik et al. Eur J Pain 2006;10:
2Scott et al. J Bone Joint Surg Br 2012;94:974-81

5. Chronic pain and TKR
Systematic review found that 20% of patients experience
moderate-extreme pain in their replaced knee1
Over 60,000 TKRs performed in NHS each year = 12,000
new cases of chronic pain after TKR every year
Likely to increase with rise in projected need for TKR2
Chronic post-surgical pain not unique to TKR3
1 Beswick et al. BMC Open, 2012
2 Kurtz et al. J Bone Joint Surg Am,  :780-5
3Macrae et al. Br J Anaesth,  :77-86

6. Chronic pain and TKR
Interview study with 28 patients experiencing chronic pain after TKR1
“. . .It’s disappointing because you think it’s gonna be so much better after you’ve had it done, and really you’re not”
“Depressed, totally depressed, sad, miserable, charred off, all the things that go with that that you can think of”
“. . . I just don’t know what to do with it I was in so much pain I said to my husband, and it’s only him I’d tell, I wouldn’t tell the family, I said if I don’t do something I shall, well I shall jump off the bridge”
1Jeffery et al 2011, Arthritis Care and Research. 63, 2, 286–292

7. Assessment of pain Clinician-administered tools
Patient-report outcome measures
Quantitative Sensory Testing
Recent innovations

8. Clinician-administered tools
Completed by healthcare professional
Often composite measures e.g. American Knee Society Score includes assessment of range of motion, stability, alignment, pain, function
Discrepancies between clinician and patient ratings of health1
Clinicians often underestimate their patients’ pain severity2 – most marked with moderate-severe pain
1Hewlett S. J Rheumatology, 2003; 30,
2Mantyselka et al. British Journal of General Practice, 2001; 51,

9. Patient-reported outcome measures
Generic questionnaires
Measure general health
SF-36 – general bodily pain
Disease-specific questionnaires
Measure pain characteristic of a particular condition
ICOAP – aching and sharp pain of osteoarthritis
Joint-specific questionnaires
Measure pain in a particular joint
Oxford knee score – knee pain

10. Patient-reported outcome measures
Pain domains assessed by questionnaires
Pain severity e.g. WOMAC pain scale
Pain qualities e.g. McGill Pain Questionnaire
Neuropathic pain e.g. PainDETECT
Pain-related disability e.g. Chronic Pain Grade

11. Patient-reported outcome measures
Many different pain assessment tools available
54 different tools used over 10 year period1
Advantages
Capture patients perception of pain
Efficient
Cost-effective
Disadvantages
People can experience difficulties in expressing their pain on a standardised questionnaire format
1 Wylde et al. Arthritis Care and Research, under review

12. Patient-reported outcome measures
Think aloud study1: 20 patients with painful TKR completed
the Chronic Pain Grade
Difficulties indentified:
Fluctuating nature of pain
Accounting for co-morbidities and pain elsewhere
Adjustment to pain
Could distort estimates of pain severity and impact
1Wylde et al. Osteoarthritis and Cartilage 2012; 20, 102-5

13. Quantitative Sensory Testing (QST)
Can be used to investigate pain mechanisms
Assesses participants’ responses to external stimuli to identify abnormalities in pain processing
Pain thresholds commonly measured
Has been used to demonstrate patients with knee OA have central pain sensitisation, which is associated with chronic pain after TKR1
1Wylde et al. Rheumatology. 2012 ;51(3):535-43

14. Recent innovations: colour and pain
Group interviews with 17 patients with painful knee OA
Associations between colour and pain:
High intensity pain = red
Absence of pain = colours associated with emotion
Aching pain = dull colours
Sharp pain = bright colours
Majority of patients could envisage using colour to talk
about their pain with healthcare professionals
1Wylde et al. Musculoskeletal Care, in press

15. Conclusions Chronic pain after TKR is prevalent
Many patients experience psychological distress from this pain
Many different pain assessment methods available - none are perfect
Awareness of these different methods could improve pain assessment in a clinical setting

16. Thank you for your attention Musculoskeletal Research Unit
School of Clinical Sciences, University of Bristol, Avon Orthopaedic Centre