If you are scheduled to undergo joint replacement surgery you are likely to be suffering from a degenerative condition such as osteoarthritis, which causes the loss of cartilage in the joints leading to pain, stiffness and a loss of movement. Alternatively, you may have sustained a serious injury to your joint that requires immediately replacement with an artificial implant.
If you are waiting for surgery and you are overweight or obese, your orthopaedic surgeon may recommend losing weight before your procedure. As surgeons, we recognise how challenging it can be to hear this, but there are some very good reasons for it, as many research studies have shown.
What research shows
The main reason is that being overweight increases the risk of complications from joint replacement surgery. An article in the Annals of The Royal College of Surgeons of England identified nine separate papers looking at the impact of Body Mass Index (BMI) on total hip replacement outcomes. Studies found that patients who were obese experienced longer operations, more blood loss and needed more intra-operative blood transfusions.
It also looked at nine studies into the outcomes of total knee replacement surgery and found that obesity was linked to increased length of stay in hospital, higher complication rates and more patients being discharged to a rehabilitation centre rather than being sent straight home. Patients who are morbidly obese (a BMI of more than 40) are most at risk, with a greater chance of wound problems, infections and ligament damage.
How being overweight affects your joints
Even carrying a small amount of extra weight puts extra pressure on your joints. In someone of a healthy weight, for example, the knees absorb around 1.5 pounds of force with every step, but experts estimate that being 10 pounds overweight adds 15-50 pounds of pressure. Not only does this make you more likely to develop osteoarthritis but if you have the condition already, it is likely to worsen it. This is because the condition can cause misalignment of the joint, leading to further pressure and damage.
Fat constantly releases proteins that cause inflammation. These proteins spread throughout the body causing small amounts of inflammation everywhere, including in the joints. This makes joints more likely to develop osteoarthritis. In fact, obese people are twice as likely to have hand osteoarthritis as people who are not overweight.
People with osteoarthritis who are obese are less physically active that people of a healthy weight, they take more medication and are at higher risk of becoming disabled says The Arthritis Foundation.
How common is the problem?
According to the Centers for Disease Control and Prevention, 72% of Americans are overweight or obese. Nearly a quarter (23%) of those who are overweight and nearly a third (31%) of those who are obese have been diagnosed with arthritis. House of Commons obesity statistics suggest that 28% of adults in England are obese and a further 36% are overweight.
Why losing weight helps
Losing weight helps to relieve pressure on the joints – for every one pound of weight lost, four pounds of pressure is removed from the knee joints. It also reduces pain and inflammation and can limit the severity of arthritis. In 2018, the International Journal of Clinical Rheumatology published a study of 171 patients with rheumatoid arthritis which showed that those who lost weight were three times more likely to see an improvement in their symptoms compared to those who did not lose weight. A 2017 study published in Radiology reviewed MRI scans in 640 overweight or obese people with osteoarthritis of the knee. Those who lost weight over four years showed slower rates of cartilage deterioration.
If you are waiting for a joint replacement – particularly at this time when waits may be longer than normal – losing weight means your quality of life will be improved before surgery, your pain levels will be lower and progression of arthritis will be slower. According to The Arthritis Foundation, losing 10% of your body weight can cut arthritis pain in half and losing 20% can reduce it by another 25% or more.
Once you have had your surgery, your outcomes are likely to be better with a lower risk of complications, a shorter hospital stay and greater chance of making a good recovery. Losing weight can also lower your blood pressure and reduce the risk of developing heart disease and diabetes.
Talk to your orthopaedic surgeon for advice about losing weight prior to undergoing joint replacement surgery.
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