Arya M. Sharma, MD

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Pain is one of the most common and debilitating problems in patients challenged by severe obesity. Not just a consequence of mechanical complications of obesity (osteoarthritis, back pain, plantar fasciitis, fibromyalgia, etc.), pain is often a key barrier to physical activity and thus weight management. In fact, excess pain can promote psychological (e.g. depression, anxiety) and behavioural (e.g. binge eating) factors that may further promote weight gain.

This issue is of even more importance in patients who display the now well-described phenomenon of pain catastrophizing, or the maladaptive responses to pain (tendency to focus on and magnify pain sensations with an intense sense of unbearable suffering and helplessness) that plays an extremely important role in how pain is perceived and processed. Pain catastrophizing now accounts for a substantial proportion of pain-related disability.

Studies in patients with fibromyalgia show that pain catastrophizing is associated with increased activity in brain areas related to anticipation of pain (medial frontal cortex, cerebellum), attention to pain (dorsal ACC, dorsolateral prefrontal cortex), emotional aspects of pain (claustrum, closely connected to amygdala) and motor control. Thus, catastrophizing influences pain perception through altering attention and anticipation, and heightening emotional responses to pain.

In another recent study by Tamara Somers and colleagues from Duke University, morbidly obese patients with osteoarthritis (OA) reported higher levels of pain catastrophizing than OA patients in the overweight and obese category. The severely obese patients who engaged in a high level of pain catastrophizing reported having much more intense and unpleasant pain, higher levels of binge eating, lower self-efficacy for controlling their eating and lower weight-related quality of life.

The relationship between pain catastrophizing and eating behaviour is of particular interest, as high-fat and high-sucrose foods have been shown to increase pain tolerance. Thus, binging on highly-palatable foods may be a compensatory response to emotional distress and pain. It is not difficult to see how patients can enter into a vicious cycle of pain, increased eating, weight gain, more pain, more eating, and so on.

In routine practice, pain catastrophizing can be easily and reliably assessed with questionnaires like this one, which can be scored like this.

Fortunately, pain catastrophizing is responsive to cognitive behavioural therapy, with clinically relevant improvements in upto 50% of individuals.

I would have little doubt that failure to recognize and address pain catastrophizing increases the likelihood of further weight gain and disability in patients with severe obesity.

AMS
Edmonton, Alberta

Yesterday, I came across a recent article on osteoarthirits by Simon Juang from the University of British Columbia, published in the latest issue of Parkhurst Exchange.

Given that osteoarthritis (OA) is probably the most common cause of pain and disability in patients with obesity, as a non-expert, I found the article most informative and relevant.

The following are some of the key pieces of information I gleaned from this overview:

First of all, I was surprised to learn that OA is not always painful, but on the other hand, that not all joint pain, simply because there may be radiological signs of OA, is actually due to OA. In fact, quite often the pain may result from the structures around the joint, i.e. the muslces, ligaments, tendons, bursae, osteophytes, injury, etc. As the course of treatment may well be different, proper diagnosis of the actual source of pain is essential.

The 4 pillars of OA management include:
- patient education
- non-pharmacological interventions
- drug therapy
- appropriate referral

The 4 goals of treatment are:
- reducing pain
- maintaining range and strength
- preserving function
- dercreasing the rate of progression

As expected, the basic joint health program starts with “optimal weight”, whereby however, Huang automatically assumes that this can be fixed by “proper diet”, best achieved by referral to a dietitian (readers of these pages will likely appreciate that if obesity management was indeed that simple, we would probably not have a crisis).

Other aspects of the joint program involve physiotherapists (exercises, heating pads, nerve stimulation, etc.), occupational therapists (activities of daily living), but also orthoticists, or podiatrists.

The article also lists a number of useful resources for patients, which I list here:

- The Athritis Society
- Arthritis Resource Guide for BC
- OASIS (OsteoArthritis Service Integrated System, Vancouver Coastal Health)
- Joint Health, Arthritis Consumer Experts
- Alberta Bone and Joint Institute
- Canadian Orthopedic Foundation

Remember, while managing pain and increasing mobility will not automatically result in weight loss, impaired mobility is certainly a major barrier to any weight management program.

AMS
Edmonton, Alberta

Based on the number of patient who have told me that their orthopedic surgeons require them to lose unrealistic amounts of weight before they will be considered for knee surgery, I would assume that surgical outcomes in patients with severe obesity are so miserable that few surgeons are willing to risk surgery.

But is this really true?

This question was addressed by Rajgopal and colleagues from Western University, London, Ontario just out in the Journal of Arthroplasty.

This study evaluated the 1-year outcomes in 550 patients who underwent primary total knee arthroplasty between 1987 and 2004 with a primary diagnosis of osteoarthritis. Outcomes were measured using the Western Ontario and McMaster Osteoarthritis Index [WOMAC].

Although 1-year outcomes were indeed slightly worse for patients with a BMI >40, compared to patients with lower BMIs, it was the severely obese patients that actually showed greater improvement in function compared with normal weight or less obese patients.

This data is quite consistent with previous reports that obesity per se should neither be a contraindication for joint replacement surgery nor is it a predictor of less satisfaction or pain relief in these patients, despite somewhat less mobility.

Denying patients joint replacements because of their weight or expecting them to lose unrealistic amounts of weight prior to surgery is not evidence-based medicine.

AMS
Toronto, Ontario

Overweight and obesity are well-established risk factors for osteoarthritis and a major factor in driving the increasing demand for hip and knee replacements.

How does being overweight or obese affect functional outcomes of hip surgery?

This question was addressed by André Busato and colleagues from the Institute for Evaluative Research in Orthopaedic Surgery, University of Berne, Switzerland in a paper just out in Obesity Surgery.

Busato and colleagues quantified the role of high preoperative BMI on long-term pain status and functional outcome after total hip replacements in a multi-center cohort of 20,553 primary hip replacements (18,968 patients) and 43,562 postoperative clinical examinations for a follow-up period of up to 15 years.

Despite equal pain relief in obese and lean patients, there was an almost perfect dose-effect relationship between preoperative BMI and decreased ambulation during the follow-up period.

This means that despite improvement in pain, patients with higher BMIs tend to regain less mobility following the hip replacement.

While the authors suggest that lifestyle management and pre- or post-surgical weight loss will improve outcomes, this has yet to be demonstrated in a large randomized trial.

It may well be that other factors unrelated to pain may be affecting mobility in heavier patients. In fact many factors that may have led to the weight gain in the first place may not be resolved simply by having a hip replacement.

This observation is not different from that of a previous study that I recently blogged on which reported that back surgery for pain relief in patients with spinal stenosis does not automatically result in increased mobility or weight loss.

Obesity is a multifactorial chronic disease and the long-term impact of educational and behavioural interventions is modest at best.

When present, obesity has to be addressed with the same interdisciplinary acumen and persistence as any other chronic disease.

AMS
Edmonton, Alberta

Immobility, due to pain or otherwise, is certainly a major contributor to weight gain. Pain is indeed often presented by overweight and obese patients as a factor limiting their ability to lose weight.

Given the widely-held (but false!) belief that exercise is the most effective way to lose weight, the general expectation of both patients and health professionals is probably that restoring mobility by relieving pain will enable patients to be more physically active and thereby lose weight.

But is this actually the case?

This issue was recently addressed by Ryan Garcia and colleagues from the Department of Orthopaedic Surgery, Case Western Reserve University, Cleveland, OH in a study just out in the Journal of Bone and Joint Surgery.

Garcia and colleagues examined weight changes in 63 overweight and obese patients with neurogenic claudication who experienced substantial pain relief after lumbar decompression surgery for spinal stenosis. Although Zurich Claudication Questionnaire (ZCQ) Symptom Severity and Physical Function scores significantly improved by a mean of 56.4% and 53.0%, respectively, body weight and BMI significantly increased by 2.48 kg and 0.83 kg/m(2), respectively.

Overall, an average 34 months after surgery, 35% of the patients had actually gained at least 5% of their preoperative body weight while only 6% of the patients weighed at least 5% less than before their operation. The vast majority (59%) remained within 5% of their preoperative body weight.

This study, consistent with several previous studies on joint surgery, nicely documents that increased mobility after pain-alleviating surgery does not necessarily translate into weight loss - in fact, most people will either continue to gain weight or simply stay the same.

Obviously, this should not be an argument against alleviating pain in obese patients - no one deserves to live with pain. It just goes to show that increased mobility alone is not likely to substantially lower body weight - at best, it may prevent further weight gain (difficult enough even at the best of times).

This is probably something patients should be counseled about to not raise any false expectations.

On the other hand, it is important to note that this was not a weight-loss study. This means, that patients were not expressly counseled for weight loss or offered obesity treatments.

The question therefore remains whether or not improving mobility in patients by alleviating pain would improve efficacy of obesity management strategies (which I believe it would).

That is obviously a study that remains to be done.

AMS
Edmonton, Alberta