New study finds link between higher BMI and poor outcome after shoulder surgery

BMI and shoulder surgery complicationsThe higher your BMI, the more likely you’ll experience a poor result from shoulder surgery. So, how are the two connected and what kind of complications could arise?

Understanding the study

Researchers from the Mayo Clinic, Rochester, Minn, analysed data taken from 4,567 shoulder arthroplasty patients from the years 1970 to 2013. The findings were published in The Journal of Bone and Joint Surgery.

Approximately 43% of patients were diagnosed as obese, which meant their BMI was at least 30. So, the researchers began looking at the correlation between BMI and shoulder surgery complications.

It was discovered that 302 patients experienced complications such as a loose implant and a mechanical failure, which resulted in the need for a revision surgery. A further 62 patients were also required to undergo a separate further operation. Interestingly, it was revealed that patients who were obese at the time of the surgery, had an increased chance of suffering these complications.

Worryingly, the chances of developing these complications increased by 5% for every unit increase in BMI of 35 and over. However, that wasn’t the strongest link found between BMI and shoulder surgery compilations. The study also showed that patients with a BMI of 35 or over, also had an increased risk of wound infections, with each increased BMI unit over 35, adding a 9% increased risk of infection.

It wasn’t all bad news, however. The study showed no link between BMI and an increase in the risk of blood clots – a complication which can be potentially deadly.

BMI also increases functionality risk in shoulder surgery

While the study largely focuses upon an increased BMI and shoulder surgery complications, previous studies have also shown it can have an effect on functionality too.

In 2011, a study revealed that patients undergoing surgery to repair rotator cuff injuries experienced an increased risk of mobility issues. Obese patients were also likely to stay longer in hospital and the shoulder operation also took longer.

Why does your BMI matter?

The theory behind the link between a high BMI and shoulder surgery complications is that the heavier a patient is, the more stress it places upon the implant. So, a high BMI will place additional pressure onto the implant, increasing the likelihood it will fail.

It also increases the chances of developing an infection after surgery. This is thought to be caused by the essentially ‘dead space’ which is left behind by excessive fatty tissues, along with changes to the immune system caused during surgery.

However, although obese patients do tend to experience poorer results, they still report the surgery has made some improvement to the condition.

Overall, what really makes this study stand out, is that it’s the first to actually look at the risks associated with BMI increases of just one increment. Most studies tend to focus more on BMI ranges, which don’t provide an accurate understanding of the increased risks involved.