Why does my knee still hurt after knee arthroplasty? Because they only treated your knee, not your central nervous system!   January 1st, 2015

Osteoarthritis (OA) of the knee has long time been considered as a structural pathology with a clear nociceptive explanation, resulting from joint degeneration. Nevertheless, recently awareness is growing for the involvement of the central nervous system in the amplification of pain in OA. This may explain why many patients still suffer chronic pain after surgery, long time after removal of the source of nociception. 

Therefore Kim et al. (2015) investigated the influence of the level of preoperative centrally mediated symptoms measured by the Central Sensitization Inventory (CSI) on pain intensity after total knee arthroplasty for OA. Pain was measured 1 and 3 months after surgery in 90 patients. 

Patients with preoperative CSI =40 complained of a greater pain intensity and medication use immediately after surgery. The high CSI score group also showed a less favorable outcome in terms of pain relief on follow-up at 1 month and 3 months after surgery. A CSI score =40 was even the strongest determinant for predicting a persistent pain 3 months after surgery among demographic and pain-related variables.

In conclusion patients with a pre-operative dominant picture of central sensitization, measured with the CSI, seemed to be at higher risk of persistent pain, and a high CSI score was predictive of low patient satisfaction in terms of pain relief after surgery.

Further reading: Kim et al., Pain Practice 2015; 15(6):E46-53. 

Mira Meeus