New horizons – Vertebral body stenting

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Vertebroplasty and kyphoplasty are well-established minimally invasive treatment options for compression fractures of osteoporotic vertebral bodies. Paul Heini (orthopaedic spine surgeon) points out, however, that possible procedural disadvantages include incomplete fracture reduction or a significant loss of reduction after balloon deflation, prior to cement injection. Vertebral body stenting uses a specially designed catheter-mounted stent which can be implanted and expanded inside the vertebral body.

Heini said, “We know that vertebroplasty and kyphoplasty are not really capable of restoring vertebral body height and the kyphotic deformity, which have a huge impact on the patient’s outcome as they affect spinal load and trunk muscle force. The goal is to restore height, but while we have partly achieved this, in general the outcome with kyphoplasty alone is not always positive because as soon as the balloon is deflated, you lose the height restoration.”

 

Heini told delegates that Sebastian Furderer et al tried to use vascular stents and published their relatively modest achievements ten years ago. Only minor corrections could be achieved with conventional stents. Then the idea was revisited and new stents were evolved which allow a higher expansion.

Heini said small studies had shown that efficient reduction was achieved using the procedure and the stent and cement helped maintain reduction. He said that a series of tests had shown that the net gain of height was superior with a stent, than with a balloon only.

 

“The clinical problem of osteoporosis is there and it is growing. The feasibility of the stent has been shown in vitro. It is clearly superior to balloon kyphoplasty. Yes, we can restore height, impact of height restoration is an open question. We have extensive clinical trials running, to try and compare the different clinical modalities,” he said.

 

Limitations

 

Heini said that this treatment was not always easy to use. If, for instance, stents get into early contact, they cannot expand correctly. “There have been some cases where the stents have detached very early and this has prevented their expansion. This is an issue because you have to be very precise in your surgery in order to achieve good results,” Heini said.

He told delegates that they had to be very cautious and that the pre-operative plan for this technique was very important. While the majority of cases can be performed easily, Heini also discussed some complications with the procedure. “Recurrence of pain is an issue, and this can be as a result of a new fracture or as a result of a sintering of the stent, due to the fact that the cementing was not sufficient.

 

“These complications usually occurred in the lumbar spine, which is typical, because a huge quantity of cement is needed to achieve a sufficient support in this region,” said Heini. Heini, who began using cement reinforcement early on to treat osteoporotic fractures was also involved in standardising the principles of this treatment, and  developing new tools to restore vertebral body height, spoke to Spinal News International on  the new procedure.

 

How the idea evolved…

 

“First of all the principle or the goal of this treatment is to re-stabilise the bones and this can be achieved with a simple vertebroplasty. When Kyphon came up with the balloon, the initial enthusiasm was a bit calmed down when we realised that even if we can restore height, as soon as we relieve the pressure on the balloon, we lose quite an important part of the initial reduction.

 

It is still difficult to determine how much importance is actually associated with the reduction. We often see cases where we feel the restoration of height probably has an impact on the risk for new fractures, and also on the degeneration of the disc. That is the motivation to use these restoration techniques and therefore the idea to use the combination of the balloon with a stent, which is used so successfully for other interventions came up and it was also developed for the spine.”

 

Where are we now?

 

 “We are in an initial phase and have just assessed the technique in the last year. At the moment, we have set up a very big study design comparing conservative treatment against stenting, comparing  vertebroplasty against stenting and comparing kyphoplasty against stenting in a randomised fashion.We have a European multicentre trial, sponsored by Synthes, running at the moment and are just collecting data. I cannot provide any preliminary results as the study started early this year so there are no results available at the moment. Let us see what results we get!”

 

Message on the procedure

 

“First of all, be critical with the indication, that is an issue. We have to carefully select these patients that need a restoration. This means if they have more than 15 degree of kyphosis, if they have an important height loss and they still have the potential of height restoration, then this might be a treatment option.

 

Be aware that the surgical technique is much more demanding than just a simple vertebroplasty procedure. You need to do pre-operative planning and the procedure per se is more demanding regarding expansion of the stent and so on, you are going to implant a stent, it is not just a little bit of cement, this needs to be kept in mind, when you start doing this surgery.”

Commenting on the procedure Afshin Gangi, professor of Radiology, University Hospital of Strasbourg, and one of the medical editors-in-chief of Spinal News International said, “One of the key indications for this treatment is traumatic compression fractures of non-osteoporotic patients. These are typically young patients with fresh fractures.

“It is important that there is no instability, so the goal of the procedure is not just consolidation, but augmentation to restore height. Stents are important in these cases because young patients have long life expectancy and it is important to preserve their stature.”

 

Gangi also stresses that it is important to perform vertebral body stenting before 7–10 days after the fractures; i.e in very fresh fractures as after that fibrosis sets in and it is very difficult to open the stents and to restore height. The procedure is much more sophisticated than a simple vertebroplasty” maintains Gangi.

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