Nocebo Confession: this image makes my knee hurt!
The recently published prospective (March 2014) Future directions in painful knee osteoarthritis: Harnessing complexity in a heterogeneous population really breaks-down some wonderful concepts about pathoanatomy and pain perception.
The article reports that 50% of individuals with osteoarthritis-like knee pain have positive radiographs for osteoarthritis (OA). Interestingly enough, 50% of those with positive radiographs for OA have knee pain. Citing the NIH they quote “it is important to separate conceptually the disease process of OA and the syndrome of musculoskeletal pain and disability.” They also refer to N. Hadler’s paper Knee Pain is the Malady, Not Osteoarthritis, which is a wonderful title indeed!
The authors propose a new conceptual model which is outstanding in breadth and scope. They delineate the disease process into three contributing categories: 1) Knee pathology 2) Psychological distress 3) Pain neurophysiology.
Knee pathology involves the regular and commonly held positions about OA. They include the radiographic (X-Ray) evidence, the chondral changes, osteophytes, the joint narrowing, the “bone-on-bone”, the “you have the knees of a 90 year old.” This part of the puzzle obviously contributes, but the relationship is NOT 1-to-1 for pain and dysfunction. – Try explaining that to someone who has knee pain, has been told they have OA and been told they have the knees of a 90 yr old. It will be a long discussion. Of course there are the biomechanical stresses on the knee including increased body mass and joint positioning that are implicated in the knee pathology puzzle piece.
The psychological distress part has to do with fear of movement (moving could cause pain!!) and catastrophizing (ruminating over the situation and winding it up into a hypersensitive syndrome) and other factors (don’t want to give it all away, read the article!) similar to other chronic pains. It is shown that the better the coping mechanisms and the better the positive belief strategies that the patient can employ the better the outcomes.
The pain neurophysiology aspect is… well, please allow me to quote: Continue reading →