Severe Persistent Knee Pain Despite Total Knee Replacement
Interesting study out this week on the percentage of patients who continue to experience severe persistent pain despite having their knees replaced. What was really surprising was that 44% of total knee replacement and 27% of total hip replacement patients continued to experience post-surgical pain of any severity 3-4 years after surgery. More surprising was that 15% of total knee replacement patients reported severe to extreme persistent pain despite the invasive knee surgery. The persistent pain was most commonly described as aching, tender, and tiring. Major depression was more common for these patients with this complication after knee replacement (this is likely a confounder, as who wouldn’t be depressed after going through an invasive surgery like this to get rid of knee pain and still having severe knee pain!) More importantly, the study authors stated that pain elsewhere was associated with persistent pain after joint replacement. However, rather than concluding (IMHO) that this may mean that the knee or hip may not be the cause of the knee or hip pain in the first place, the authors went in a different direction. They stated, “The association between the number of pain problems elsewhere and the severity of persistent post-surgical pain suggests that patients…may have an underlying vulnerability to pain.” Which is an erudite way of saying that patients who still have pain after our joint replacement surgeries must be wimps! I would interpret this data very differently. We’ve seen many patients with hip or knee pain and an x-ray that looks like arthritis who have been told they needed joint replacement. Many of these patients have pain coming from elsewhere that is referred to the hip or knee, as we’ve been able to solve their pain problems without surgery. In these patients, replacing their joints won’t do much good. These concepts of referred pain are discussed in our book, Orthopedics 2.0. The upshot, severe pain despite joint replacement is more common than I would have guessed and based on our experience, is often caused by an inaccurate diagnosis of the pain generator before the surgery. So if you’re considering a knee or hip replacement, it likely makes sense to insist that someone take the simple step of numbing the joint under imaging guidance to ensure that it’s really the culprit. If this doesn’t take away >75% of the pain, than this isn’t the surgery for you. In that case, keep searching for a cause (which in our experience is often the low back).