Weight loss surgery has many proven benefits, including reducing blood pressure, improving blood sugars, and reducing cardiovascular risk. Now, data from a large multicenter study of bariatric surgery in the US suggest long-lasting improvement of pain and physical function can be added to this list.
What did the study look at?
This study followed nearly 1,500 people for up to seven years after they had either Roux-en-Y gastric bypass or sleeve gastrectomy, the two most common bariatric surgery procedures. Most of the participants were female (80%) and white (82%), with Hispanic (4%) and Black participants (11%) less well represented. Their ages ranged from 38 to 55, and all had been diagnosed with severe obesity (a body mass index of 35 or greater).
Before their surgery, participants filled out questionnaires reporting on their physical abilities, pain, health, and quality of life. Many also were tested for measures of physical function and mobility, such as being able to walk 400 meters in seven minutes or less. Some reported severe or even disabling knee or hip pain, a symptom of osteoarthritis. Assessments were repeated annually for up to seven years.
What were the findings?
When the study concluded, 41% to 64% of participants reported improvements in body pain and physical function, as well as objectively measured walking ability. Additionally, 65% to 72% of those with osteoarthritis symptoms felt less knee and hip pain. And 41% of those unable to walk 400 meters in less than seven minutes before surgery were now able to do so.
Not all measures were better; for example, medication use for back pain before weight loss surgery and at the end of the study remained the same. It's also worth noting that not everyone experienced improvements in pain and physical function. And the lack of a control group that did not have weight loss surgery makes it hard to be sure whether the positive changes were due to surgery, and whether one type of surgery was better than the other.
Why are these results impressive?
We know that the improvements in health and physical function after bariatric surgery are greatest in the first one to two years after surgery. Between three to seven years after surgery, the positive effects on weight, cardiovascular and diabetes health metrics, and health-related quality of life generally decline, even though the net effect remains positive overall.
Most studies of joint pain, physical function, and work productivity after weight loss surgery are limited to no more than two years of follow-up. As a result, how long people are able to sustain improvements they make after surgery has been unclear. This study shows evidence of long-term positive changes in important clinical outcomes that matter in daily life: how much body or joint pain people experience, what tasks they can perform for themselves, how mobile they are, and how they feel about their quality of life.
Why does obesity worsen joint pain?
Obesity contributes to damage of the soft tissues in the joints (note: automatic download), which can lead to osteoarthritis, a progressive disease caused by wear and tear on the joints. The hips and knees are most commonly affected. Each pound of body weight puts four to six pounds of pressure on each knee joint, and people with obesity are 20 times more likely to need a knee replacement than those who are not overweight.
The bottom line
Obesity clearly has harmful effects on the joints. Bariatric surgery, which is an effective treatment for significantly reducing body weight, can improve pain and physical abilities, and reduce hip and knee osteoarthritis symptoms.
In addition, for those considering total knee replacement surgery, weight loss from bariatric surgery can reduce the risk of complications (such as infection, blood clots, stroke, or heart attack). Better still, it lowers the chance of needing total knee replacement at all.
Taken together, these results show that bariatric surgery can have long lasting effects beyond those we normally think of in improving blood pressure, blood sugar, and general health; it can reduce pain and improve physical function and quality of life, as well.