Knee osteoarthritis severity doesn’t correlate well with pain
PainSci summary of Finan 2012?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focussed on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided at the bottom of the page, as often as possible. ★★★☆☆?3-star ratings are for typical studies with no more (or less) than the usual common problems. Ratings are a highly subjective opinion, and subject to revision at any time. If you think this paper has been incorrectly rated, please let me know.
Many lines of evidence suggest that pain is not tightly linked to tissue damage. If so, there should be people with knees that look bad on a scan, but feel fine, and vice versa. This study of 113 people found exactly that: as Tony Ingram summarized it, people “who had a little arthritis and high pain & people with severe arthritis but low pain.”
And why did the hurters hurt? High sensitivity to pain in general: “central sensitization” (see Woolf). Their knees weren’t the problem — their nervous systems were.
OBJECTIVE: Radiographic measures of knee osteoarthritis (K-OA) pathology have modest associations with clinical pain. We sought to evaluate possible differences in quantitative sensory testing (QST), and psychosocial distress profiles between K-OA patients with discordant versus congruent clinical pain reports relative to radiographic severity measures.
PATIENTS AND METHODS: 113 participants (67% women, Mean age = 61.05 ± 8.93) with K-OA participated in the study. Radiographic joint pathology was graded via the Kellgren-Lawrence scale. Central sensitization was indexed through quantitative sensory testing, including heat and pressure pain threshold, tonic suprathreshold pain (cold pressor test), and repeated phasic suprathreshold mechanical and thermal pain. Subgroups were constructed by dichotomizing clinical knee pain scores (median split) and knee grade scores (1-2 vs. 3-4), resulting in four groups: Low Pain/Low Knee Grade (n=24), High Pain/Low Knee Grade (n=30), Low Pain/High Knee Grade (n=27), and High Pain/High Knee Grade (n=32).
RESULTS: Multivariate analyses revealed significantly heightened pain sensitivity in the High Pain/Low Knee Grade group, while the Low Pain/High Knee Grade group was less pain sensitive. Group differences remained significant after adjusting for differences on psychosocial measures, as well as age, sex, and race.
CONCLUSION: The results suggest that central sensitization in K-OA is especially apparent among patients with high clinical pain reports in the absence of moderate to severe radiographic evidence of K-OA pathology.
These two articles on PainScience.com cite Finan 2012 as a source:
- PS Save Yourself from Patellofemoral Pain Syndrome! — Patellofemoral pain syndrome (aka runner’s knee) explained and discussed in great detail, including every imaginable self-treatment option and all the available scientific evidence
- PS Your Back Is Not Out of Alignment — Debunking the obsession with alignment, posture, and other biomechanical bogeymen as major causes of pain