New therapy for rotator cuff tears

Our shoulder joint is a true multi-talent. As the most mobile joint in our body, it allows movements along several bending planes and the axis of rotation. Shoulder shrugs, push-ups, wild circles – the shoulder does it all. We have the special structure of the joint to thank for that. The head of the humerus lies in the very flat socket of the shoulder blade and is held in place by a group of muscles called the rotator cuff.

However, this dynamic fixation also makes the shoulder prone to injury. Dislocations are particularly common in the shoulder joint. At a young age, it takes a fall on the arm stretched backwards or leverage on the fixed upper arm. The risk of injury increases with age. The structures of the rotator cuff are then damaged by ageing and wear processes. In old age, even a minor trauma, such as a collision or great force, can be enough to cause tears of the rotator cuff.

“In most cases, an injury to the tendons of the rotator cuff initiates a cascade of further degeneration of the shoulder,” reports, DDr. Jakob Schanda, orthopaedic surgeon and trauma surgeon at the AUVA Trauma Centre Vienna, Meidling site and member of the shoulder regeneration group at the Ludwig Boltzmann Institute for Traumatology, the research centre in cooperation with AUVA. “Torn tendons cause the muscles of the rotator cuff to become fatty and the upper arm bone, which is less activated due to the protective posture, becomes osteoporotic and more susceptible to fractures.” This bone loss in the humeral head can occur even after surgical repair of the rotator cuff and is often associated with repair failure.

Together with his co-authors, including group leader Priv.-Doz. Dr. Rainer Mittermayr, Dr. Schanda investigated for the first time the effect of zoledronic acid on the bone microarchitecture of the humeral head after surgical restoration of the rotator cuff. Zoledronic acid is one of the most common therapies for osteoporosis because it is inexpensive and easy to administer. Patients are injected with the biophosphate once a year, which significantly reduces the risk of bone fracture. It also showed effect in the case of the shoulder joint. By means of micro-computed tomography, it was clearly shown within the intervention group that bone formation and bone density were significantly higher after eight weeks than in the control group, which had not received an injection. The observations suggest that therapy with zoledronic acid could inhibit bone resorption and increase bone density. Jakob Schanda was awarded the prize for the Best Experimental Paper of the Austrian Society for Trauma Surgery for his study in 2021.

In Austria alone, about one in five people are affected in the course of their lives, the majority due to cracks in old age. For those affected, the consequences are pain during everyday movements and a reduction in their mobility. “Our study shows a simple and favourable therapy option to enable people with shoulder complaints to lead a pain-free, unrestricted and active life even in old age,” says Jakob Schanda.

He can imagine that in the future, patients could decide for a one-time therapy with zoledronic acid already at the initial consultation after a shoulder tendon rupture. By the time of the operation, they would already be benefiting from the positive effect of zoledronic acid. There are hardly any side effects. “Most people feel a little flu-like after an infusion of zoledronic acid, similar to a mild vaccination reaction,” says Schanda. There is still no clinical trial on the effectiveness of zoledronic acid in rotational cuff design. That should change by the end of 2022. Then the research team at LBI Trauma wants to study the effect of zoledronic acid in people after rotator cuff reconstruction.

In addition to the positive effect on the bone, Jakob Schanda and his co-authors discovered an additional effect of zoledronic acid on the muscles of the rotator cuff. In a follow-up study, they describe that the degradation of muscles is also inhibited. For the researchers, this is another reason to test their results in a clinical trial as soon as possible.