Friday, May 19, 2017

Vertebral Body Tethering for Scoliosis

Since the first description of spinal fusions for the treatment of scoliosis over 100 years ago, there have been significant advancements in the surgical technique, which have led to improved fusion rates, lower complication frequency, greater three-dimensional correction of the deformity and more rapid postoperative recovery.  However, spine fusions mean fewer motion segments (less spine motion) which may lead to lower function in high-level physical activity (e.g. competitive athletics) and greater chance for spine arthritis. Hence preservation of spinal motion, particularly in the low back, is a highly attractive goal.  The desire to maintain spine motion has fueled the development of various growth modulation procedures, whose goals are correct the spinal deformity and maintain motion (without fusion).  One of these promising techniques which has gained traction in the last 10 years is vertebral body tethering (VBT).

The concept of VBT in scoliosis is to alter the relative vertebral growth (right vs. left) of the front of the spine.  This is accomplished by relative slowing the vertical growth on the convex side (by tensioning of the tether) with unloading of the concave side of the vertebra, to permit greater growth.  In order for growth modulation to occur the spine need to have enough spinal growth remaining.    

 This is a patient 4 days after VBT
At present in 2017 there is no FDA-approved devices for use in the U.S. in a nonfusion, growth-modulation technique in a skeletally immature patients.  This means the use of this tether system to the children and adolescents is in an “off-label” manner. 

Studies on VBT in animal models have demonstrated proof of concept that tethering of the immature spine can alter its growth.  The first description of VBT use in humans was a case report in 2010.  Reports of VBT use in children/adolescents have been encouraging with a low frequency of complications.  At present there is limited data available on the use of VBT in skeletally-immature patients with scoliosis. 

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