MIRA University of Twente
Department of Biomechanical Engineering

Scoliosis Correction Systems

Staff members involved in Scoliosis:

Ir. Edsko Hekman

Dr. ir. Jasper Homminga

Prof. dr. ir. Bart Verkerke

PhD Students

Ir. Gerdine Meijer

Ir. Martijn Wessels


The goals of the SCOLIOSIS project are; firstly, to design correction methods for scoliotic spines, and secondly to understand what causes and progresses scoliosis.

This involves the design of new methods for the correction of scoliotic spine, as well as computational and in vitro analyses on spines.


Scoliosis is a three-dimensional deformity of the spinal column, which occurs mostly in girls during adolescence. Although certain risk factors for the occurrence and progression of scoliosis are known, the underlying cause is still unknown.

Seen from the back the spine has a C- or S-shape instead of being straight. This lateral deviation of the spine is accompanied by an axial rotation of the vertebrae. If the scoliosis is progressive, it may be life-threatening without treatment, since vital organs as the lungs and the heart become oppressed. In mild cases the curvature is treated using bracing while severe cases are treated using implanted metal rods.

Adolescent female with a scoliotic spine: external appearance and x-ray image

Within the group we have a long history of scoliosis-related design.

In cooperation with the University Medical Center Groningen, Gert Nijenbanning developed a bracing system that corrects scoliosis using force control. This brace, the TriaC, was patented and has been further developed by Baat Engineering (a spin-off company of the University of Twente) and is currently commercially available through Somas (in the Netherlands) and Boston Brace Inc. (in the US). Preliminary results of the brace in nine patients show that the brace reduces the scoliotic curve, while providing increased comfort as compared to conventional bracing. Clinical tests in a number of clinics in Europe and in the USA are taking place at this moment.

For more severe scoliotic curves we have, again in cooperation with the University Medical Center Groningen, developed an implantable scoliosis correction system that uses a rod made of Memory Metal. This system utilizes the superelastic behavior of the rod to achieve additional correction during a certain period after implantation. Due to the square cross-section of the rod, bending as well as derotation of the deformed spine can be achieved. Eventually, fusion of the vertebrae will occur. DuPuy Spine has obtained the patent rights to the device, and this year a number of these systems have been successfully implanted in patients by Veldhuizen (UMCG).

The TriaC brace

Memory metal scoliosis correction rod.

Disadvantage of all present correction rods is that the surgical treatment results in a rigid spine, because the rod is rigid and the vertebrae will fuse, meaning that the young patients will have a stiffened back for the rest of their life. Moreover, it is not possible to have early surgery when the deformity is still less severe, because surgery has to be postponed until growth has more or less stopped. Another disadvantage of existing correction rods is that they are form-controlled, i.e. they impose a shape to the spine. Due to the inevitable elasticity of the correction devices, a complete correction cannot be achieved.

Examples of scoliosis correction rods.
From left to right the systems of Luque, Harrington, Cotrel-Dubousset and Zielke

With our current research we wish to realize a non-fusion scoliosis correction device, a device that corrects scoliosis completely, but prevents fusion.

This device will realize a complete correction, because it is based on force-control, so a constant force is applied on the spine. Due to the visco-elastic and growth properties of the spine the correction forces can stay small while still a complete correction can be obtained. By applying bending forces to the spine and rotational forces to the vertebrae this device is able to correct both the lateral deviation and the axial rotation.

The device will correct the spinal deformity without increasing the rigidity of the spine to the point where it would cause vertebral fusion, so the flexibility of the spine stays intact. The device will allow growth, so it can be applied in an early stage, when the deformity is less severe.

To optimize the design of the non-fusion scoliosis correction device we will develop a numerical simulation model of the mechanical behavior of the spine with the scoliosis correction device.

The Nonfusion Scoliosis Correction project has been funded by the Dutch Technology Foundation (STW)

More recently, the group has started to again investigate the underlying causes for scoliosis. The group of Castelein at the UMC Utrecht has developed a theory about the importance of posteriorly directed shear forces in the initiation of scoliosis. Together with the UMC Utrecht we will setup a longitudinal study to test this hypothesis using our current and future spinal models.



start Spineguide project: Gerdine Meijer

testing of non-fusion correction devises in a porcine model

start of patent procedure


analysis of normal and scoliotic spines using complete spine models

in vitro testing of fixation and correction devises

start cooperation with UMC Utrecht into etiology of scoliosis

pilot test of non-fusion implants in a porcine model


development of complete spine models

design of fixation devices, correction devices, and instruments


development of detailed spinal models

design of correction devises


start non-fusion project: Gerdine Meijer & Martijn Wessels

Getting involved

Are you a master or bachelor student and would you like to do a research project on scoliosis, please send an email to Jasper Homminga (j.homminga@utwente.nl) or Edsko Hekman (e.e.g.hekman@utwente.nl). We are always on the look-out for good students to help us analyze and solve the problems of the scoliotic spine.

Selected publications

Meijer GJ, Homminga J, Veldhuizen AG, Verkerke GJ. Influence of interpersonal geometrical variation on spinal motion segment stiffness: implications for patient-specific modeling. Spine 36:E929-935, 2011.

Meijer GJ, Homminga J, Hekman EE, Veldhuizen AG, Verkerke GJ. The effect of three-dimensional geometrical changes during adolescent growth on the biomechanics of a spinal motion segment. J Biomech. 43:1590-1597, 2010.

Busscher I, Ploegmakers JJW, Verkerke GJ, Veldhuizen AG. Comparative anatomical dimensions of the complete human and porcine spine. European Spine Journal 19, 1104-1114, 2010.

Busscher I, van der Veen AJ, van Dieën JH, Kingma I, Verkerke GJ, Veldhuizen AG. In vitro biomechanical characteristics of the spine: a comparison between human and porcine spinal segments. Spine 35: E35-42, 2010.

Busscher I, van Dieën JH, Kingma I, van der VeenAJ, Verkerke GJ, Veldhuizen AG. Biomechanical characteristics of different regions of the human spine: an in vitro study on multilevel spinal segments. Spine 34: 2858-2864, 2009.

Busscher I, van Dieën JH, van der Veen AJ, Kingma I, Meijer GJM, Verkerke GJ, Veldhuizen AG. The effects of creep and recovery on the in vitro biomechanical characteristics of human multi-level thoracolumbar spinal segments. Clinical Biomechanics 26: 438-444, 2011.



Biomedical Engineering, University Medical Centre Groningen

Orthopedic Biomechanics, Eindhoven University of Technology

Faculty of Human Movement Science, Vrije Universiteit Amsterdam

Faculty of Orthopaedics, University Medical Centre Utrecht

Faculty of Orthopaedics, Maastricht University Medical Centre



Baat Medical

DePuy Spine

ESI group