Patterns of pain after total knee joint replacement

My orthopaedic colleagues are concerned about how they choose patients who will benefit from surgery, rather than ending up with poor outcomes. It’s interesting to know that knee replacement surgery is revised mostly because of pain rather than infection, dislocation or other surgical problems. Naturally, my colleagues would like to find an easy way to pick who is going to develop chronic post-surgical pain because it would avoid a lot of bother and repeated surgeries.

Pagé, Katz, and colleagues (2015) conducted this study which was nested within a study looking at postoperative gabapentin as a way to reduce the risk of postsurgical pain. People were studied for up to 12 months, which is a good length of time for outcome studies.  They then performed a complex statistical analysis called Growth Mixture Modeling, which is “a longitudinal analysis methodology in which a latent membership to discrete trajectories is estimated” (p. 462), which uses data drawn from baseline and each data point thereafter to generate groupings of individuals based on patterns identified in the data. I’m not sufficiently comfortable with my ability to describe the statistics so I’ll refer you to the article itself, but suffice to say, the researchers were able to identify four groups, and range of movement at the knee joint between the groups was no different – so it’s not the surgery that makes the difference, but “something else”.

They found four groups: (1) People with high baseline pain, but which decreased quickly after surgery, then decreased again at 12 months after surgery. This is the kind of outcome orthopaedic surgeons and patients want to see!

(2) People with low baseline pain that continued to reduce over time. Again, a group the orthopods like.

(3) People with high baseline pain but gradually reducing over time, higher immediately post-surgery than groups (1) or (2), but generally a good outcome for everyone involved. Possibly a group that needs a bit more TLC immediately after surgery than groups (1) and (2).

(4) People with moderate levels of pain before surgery and also after, but the pain not changing much even 12 months later. Not the kind of outcome that surgeons, or people having surgery want!

What factors were associated with this not-so-good outcome?

The first thing to note is that there was no difference in terms of age or gender – and this is unusual because often it is women and older women at that who have more difficulty recovering from knee replacement surgery.  People in group (4) were slower to move in presurgical functional tests, had greater anxiety (as measured on the Hospital Anxiety and Depression Scale), and had higher scores on the Pain Disability Index.

The authors consider that patients in group (4) had similar levels of acute postoperative pain to the other groups, but didn’t report any change in their score from before surgery to the first two measurement points at 4 days and 6 weeks postop. In fact, this group of people had the same level of pain intensity or thereabouts for the next 12 months. They suggest that treatments for this group of people should be given at this 4 days to six weeks stage to try to minimise their transfer from acute postop pain to chronic postsurgical pain, and they suggest these should target “prehabilitation” and “total-body physical conditioning”.

I have some questions that still remain unanswered:

  • Why did this group of people have the same level of pain intensity as the other groups, but lower functional abilities before surgery?
  • Could general anxiety as measured by the HADS and either health anxiety or catastrophising be associated (probably yes)?
  • If a person is generally anxious, does this mean he or she is more likely to be cautious while mobilising? is this group of people at greater risk of falling/doing less/participating less in rehabilitation postop (probably yes)?
  • Why did the study authors not include pain catastrophising as a measure? Would they have changed their recommendations for prehabilitation if they’d included it as a predictor?

It’s that last question that I’m interested in – pain catastrophising is associated with poorer outcomes in many different domains including orthopaedic trauma , orthopaedic surgery (Edwards, Haythornthwaite, Smith, Klick & Katz, 2009; Forsythe, Dunbar, Hennigar, Sullivan & Gross, 2008 Homes, Williamson, Hogg, Arnold & O’Donnell, 2013 Witvrouw, Pattyn, Almqvist, Crombez, Accoe et al 2009); and pain coping (Keefe, Shelby, Somers, 2010; Campbell & Edwards, 2009.

Treating people who have high levels of pain catastrophising isn’t easy but there are a number of options that might be useful. Amongst these are pain neurobiology “education” (Therapeutic Neuroscience Education or TNE) (Louw, Diener, Butler & Puentedura, 2013), mindfulness as a strategy for dealing with anxiety and pain , graded exposure to movement using a phobia paradigm rather than a graded activity one (ie addressing the thinking rather than simply physical fitness), providing people with enhanced postop recovery pathways using a combined psychological and physical rehabilitation approach.

My concern is that by ignoring the information we have about catastrophising, and focusing instead on the reduced function alone without considering why this group are less confident and move with more difficulty, one of the relevant issues won’t be addressed. While it’s easier to just use physiotherapy and exercise to mitigate disability, it doesn’t address the underlying anxiety or catastrophising that influences the amount of attention paid to pain, the meaning pain holds for people who catastrophise, and it doesn’t teach skills to deal effectively with the anxiety or catastrophising. Unless the physiotherapists carrying out exercise programmes are well-versed in psychological approaches to reduce catastrophising, I fear this recommendation may not be as helpful as it could.


Brander VA, Stulberg SD, Adams AD, Harden RN, Bruehl S, Stanos SP, Houle T. (2003) Predicting total knee replacement pain: a prospective, observational study. Clinical Orthopedic and Related Research, 416:27–36.

Campbell, C. M., & Edwards, R. R. (2009). Mind-body interactions in pain: the neurophysiology of anxious and catastrophic pain-related thoughts. Translational Research: The Journal Of Laboratory and Clinical Medicine, 153(3), 97-101.

Edwards, R. R., Haythornthwaite, J. A., Smith, M. T., Klick, B., & Katz, J. N. (2009). Catastrophizing and depressive symptoms as prospective predictors of outcomes following total knee replacement. Pain Research & Management, 14(4), 307-311.

Forsythe, M. E., Dunbar, M. J., Hennigar, A. W., Sullivan, M. J., & Gross, M. (2008). Prospective relation between catastrophizing and residual pain following knee arthroplasty: two-year follow-up. Pain Research & Management, 13(4), 335-341.

Holmes, Alex, Williamson, Owen, Hogg, Malcolm, Arnold, Carolyn, & O’Donnell, Meagan L. (2013). Determinants of Chronic Pain 3 Years after Moderate or Serious Injury. Pain Medicine, 14(3), 336-344. doi: 10.1111/pme.12034

Keefe, Francis J., Shelby, Rebecca A., & Somers, Tamara J. (2010). Catastrophizing and pain coping: Moving forward. Pain, 149(2), 165-166. doi: http://dx.doi.org/10.1016/j.pain.2010.02.030

Louw, Adriaan, Diener, Ina, Butler, David S, & Puentedura, Emilio J. (2013). Preoperative education addressing postoperative pain in total joint arthroplasty: Review of content and educational delivery methods. Physiotherapy theory and practice, 29(3), 175-194.

Pagé, M., Katz, J., Romero Escobar, E., Lutzky-Cohen, N., Curtis, K., Fuss, S., & Clarke, H. (2015). Distinguishing problematic from nonproblematic postsurgical pain PAIN, 156 (3), 460-468 DOI: 10.1097/01.j.pain.0000460327.10515.2d

Witvrouw, E., Pattyn, E., Almqvist, K. F., Crombez, G., Accoe, C., Cambier, D., . . . Witvrouw, Erik. (2009). Catastrophic thinking about pain as a predictor of length of hospital stay after total knee arthroplasty: a prospective study. Knee Surgery, Sports Traumatology, Arthroscopy, 17(10), 1189-1194. doi: dx.doi.org/10.1007/s00167-009-0817-x

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