Aakash Agarwal1, Anand K Agarwal2, Arvind Jayaswal3, Vijay Goel2. 1. Department of Bioengineering and Orthopaedics Surgery, Engineering Center for Orthopaedic Research Excellence (ECORE), Colleges of Engineering and Medicine, University of Toledo, Toledo, OH 43606, USA. Electronic address: Vijay.Goel@utoledo.edu. 2. Department of Bioengineering and Orthopaedics Surgery, Engineering Center for Orthopaedic Research Excellence (ECORE), Colleges of Engineering and Medicine, University of Toledo, Toledo, OH 43606, USA. 3. Department of Orthopaedics, All India Institute of Medical Sciences (AIIMS), Ansari Nagar East, Gautam Nagar, New Delhi, DL 110029, India.
Abstract
BACKGROUND: Growth rods allow regular distraction of the spine to compensate for growth. Traditionally such distractions are performed every 6 months via open surgery. However with the advent of minimally invasive techniques like magnetically controlled growing rods, the distractions can be performed non-surgically. This also implies that the interval of distraction could be changed or customized based on individual patient's need. HYPOTHESIS: In this study we have hypothesized that the distraction at shorter intervals reduces the stresses on the rods which in turn reduces the chance of rod failure. OBJECTIVE: A finite element model of a juvenile spine was instrumented with growth rods and distractions were applied at different frequencies (2 months, 3 months, 6 months, and 12 months) for a period of two years to study the effects of frequency of distraction on maximum von Mises stresses on the rods for different loading conditions were studied. RESULTS: The stresses on the rods were highest for 12-month distraction (2 distractions in 2 years) and lowest for 2-months distraction (12 distractions in 2 years). CONCLUSION: It was found that the shorter intervals of distraction led to reduction of stresses on the rod for same spinal height gain in two years. Published by Elsevier Inc.
BACKGROUND: Growth rods allow regular distraction of the spine to compensate for growth. Traditionally such distractions are performed every 6 months via open surgery. However with the advent of minimally invasive techniques like magnetically controlled growing rods, the distractions can be performed non-surgically. This also implies that the interval of distraction could be changed or customized based on individual patient's need. HYPOTHESIS: In this study we have hypothesized that the distraction at shorter intervals reduces the stresses on the rods which in turn reduces the chance of rod failure. OBJECTIVE: A finite element model of a juvenile spine was instrumented with growth rods and distractions were applied at different frequencies (2 months, 3 months, 6 months, and 12 months) for a period of two years to study the effects of frequency of distraction on maximum von Mises stresses on the rods for different loading conditions were studied. RESULTS: The stresses on the rods were highest for 12-month distraction (2 distractions in 2 years) and lowest for 2-months distraction (12 distractions in 2 years). CONCLUSION: It was found that the shorter intervals of distraction led to reduction of stresses on the rod for same spinal height gain in two years. Published by Elsevier Inc.
Entities:
Keywords:
Distraction frequency; Finite element study; Interval of distraction; Juvenile scoliosis; Magnetic growth rods
Authors: Pooria Hosseini; Jeff B Pawelek; Stacie Nguyen; George H Thompson; Suken A Shah; John M Flynn; John P Dormans; Behrooz A Akbarnia; Growing Spine Study Group Journal: Eur Spine J Date: 2016-10-19 Impact factor: 3.134