Antibiotics for back pain
Recent media coverage has drawn attention to a clinical trial conducted in the UK that demonstrated the effects of antibiotic treatment for chronic low back pain . Much excitement ensued along with claims (by business associates of the author) that the findings could be worthy of a Nobel Prize. Although the results are certainly interesting and worthy of further investigation, some considerations should be made before making your conclusions. First, the antibiotic group experienced a high number of adverse events, apparently including new cases of cancer (2/45). Blinding wasn’t checked at the end of the trial so it is also unclear whether the patients suffering side effects were unblinded to their group allocation. Second, the size of the effect on disability was similar to most small scale trials on interventions for chronic low back pain. A good exercise program and education is likely to yield similar results, without the side effects. Third, the statistical techniques are not clearly reported, nor is any raw data, making the results difficult to interpret objectively. Fourth, the manuscript was rejected from a number of high ranking journals to be accepted in a relatively low impact journal in the field. Finally, if the results are valid and replicated in larger studies, these findings are only generalisable to a very small proportion of patients with chronic low back pain (less than 20%). With all these factors in mind, it may be premature to be expecting a Nobel Prize and to have already set up a private clinic (owned by the study authors) that is designed to train clinicians and implement the therapy.
Context, pain and pleasure
There are a number of social and clinical situations where normally painful stimuli can be reported as pleasurable. Think of the last time you ate a deliciously spicy curry. In physiotherapy practice, firmly massaging a recently injured, inflamed ankle elicits variable reactions from the patient, but can sometimes be reported as “feeling really good”. Researchers at Oxford have conducted an interesting experiment to shed light on this phenomenon . Subjects were randomized to two contextual conditions where they received a painful stimulus. The experimental group would receive either a moderately painful stimulus or an intensely painful stimulus (so-called ‘relative relief’ context); the control group received the same moderately painful stimulus or a warm, non-painful stimulus. What they found was that not only did the subjects in the ‘relative relief’ context report the moderate pain as less painful, they actually reported it as pleasurable. This apparent ‘hedonic flip’ was associated with activation in the reward centre in the brain, and physiological variables reflecting a reduction in threat. What does that mean? This is the first experiment to show how you can make an identical noxious stimulus evoke either a painful or a pleasurable experience, just by manipulating the context within which the stimulus is perceived. It provides further evidence for the fact that nociception is neither sufficient nor necessary for pain. Bringing this back to the clinic, we would argue that all pain should be conceptualized in this way: not just as a signal of actual or potential damage, but as a complex protective response reliant on many contextual factors. What is the context in which your patients are experiencing pain?
Factors for pain in knee osteoarthritis
A clear discordance exists between radiologic findings of knee osteoarthritis (OA) and pain. In up to 30% of cases where Grade 3 or 4 changes are present on x-ray, patients will report no pain. Researchers have performed a factor analysis as part of a large cohort study conducted in the Netherlands, to identify which variables predict whether or not you have pain in your knee . The knees of over 5000 participants were stratified according to the grade of OA. They performed a multivariate analysis to separate out the factors that were most strongly associated with higher pain levels, for a given grade of OA. Once again, there was no consistent correlation between radiographic signs and pain intensity. Patients who were female, had widespread pain, poor general health symptoms, family history and morning stiffness were more likely to experience pain in the presence of knee OA. In those with no OA on x-ray, the biggest predictors of knee pain were depression and hip OA. Interestingly, older age was found to be protective factor for knee pain. This finding supports previous research showing that reports of pain reduce with older age (your patients might like to know this!). In summary, multiple factors determine whether someone with knee OA experiences pain. Some of these factors are not modifiable (gender, family history) but others are (morning stiffness, poor general health). Education about the value of radiographs in predicting pain outcomes should be included when reassuring the concerned patient with knee pain.
Autologous blood injections for mid-portion Achilles tendinopathy
A recent double blind placebo-controlled trial published in BMJ  has examined the effect of autologous blood injections for patients with chronic mid-portion Achilles tendinopathy. Achilles tendinopathy is associated with pain and stiffness in the area of the insertion or the mid-portion of the Achilles tendon. It is common in both athletes and sedentary individuals, and is the main reason for stopping sport in 16% of athletes. Tendinopathy is notoriously difficult to treat in clinical practice, and requires a comprehensive rehabilitation program. This study paired such a rehabilitation program (12 weeks eccentric loading e.g. dropping heels off a step with varying load) with two peritendinous injections of either 3ml saline (placebo) or 3ml autologous blood (active). The suggested mechanism of the active injection is that the blood-derived cytokines and growth factors stimulate the tissue healing process. Outcomes were Achilles tendon symptoms at one, two, three and six months. Both groups improved significantly at the three month follow-up, and there was no difference between the placebo or blood injection groups. The researchers concluded that there was no effect of a blood injection over and above the placebo effect. Unfortunately there was no third group who received rehabilitation only, which could have explained how much of the treatment effect was related to this component. However, it does seem that a well-structured rehabilitation program continues to be the best treatment available for Achilles tendinopathy.