- The research in Montreal first focused upon the etiology and pathogenesis of Idiopathic Scoliosis. This started in the early 1990’s at the Ste-Justine’s Children’s Hospital in Montreal, Canada.- More than 65 researchers, led by Professor Charles H. Rivard and Dr. Christine Coillard, were involved in this research, which hadthe financial support of public and private Canadian institutions.- Dr Coillard and the team of researchers at Ste Justine Hospital knew that in order to treat Idiopathic scoliosis effectively an understanding of how and why idiopathic scoliosis progressed was critical. - Whilst a full understanding of the etiopathogenesis of Idiopathic Scoliosis may still be many years away, this research provided the group with the relevant information to better manage the scoliosis progression with conservative treatment.
This diagram summarizes the etiopathogenic concept of idiopathic Scoliosis described by Dr. Coillard. Each of the seven boxes represents an event that is critical to the onset or progression of Idiopathic Scoliosis. Each of these events will be described in detail along the presentation.The sequence of events starts with the initiating factor, which according to Dr Coillard’s etiopathogenic concept is a genetic temporary fault. This temporary fault affects the vertebral growth modulation.
- Whilst the specific location of the genetic fault is not known, there is strong evidence to suggest that it lies within the genes controlling the morphogenesis, including the Hox genes which are involved in the development of the vertebral segments.- This genetic fault causes Growth Modulation of the vertebra by provoking a temporary delay of ossification of either the right or left posterolateral segment of the vertebra compared to the posterolateral segment of the opposite side of the vertebra. -This unsynchronized osseous growth creates the 3-dimensional initial vertebral deformity, which is the next event in the sequence.- This is the scoliosis initiating factor however hormonal maturation, growth velocity and mechanical factors associated with gravity and deformity can also play a significant role in the progression of scoliosis.
- The reason why such a 3-dimensional asymmetry can occur can be explained by looking at the anatomy of the vertebra. The growth of a vertebra occurs from the vertebral growth plates.- The right and left neuro-central cartilages are the growth plates that separate the anterior part of the vertebral body from the right and left postero-lateral segments of the vertebra. They are responsible for the 3-dimensional development of part of the vertebral body, transverse process, articular process and laminae.- According to Dr. Coillard’s concept the unsynchronised growth of these neuro-central cartilages provoke the initial 3-dimensional localised vertebral deformity observed in scoliosis.
Localized 3D vertebral deformity-The initial vertebral deformity is localised in one specific segment of the spine. It is specifically confined to one vertebra plus half of the vertebra above and half of the vertebra below. - The bony deformation is 3-dimensional showing lateral wedging, anterior to posterior wedging and rotational deformity of the vertebral body, spinous processes and transverse processes. These deformities can be seen on CT scans but are not easily seen on conventional X-rays until the deformity is extreme.
- In this slide the localised 3-dimensional vertebral deformity found in the 3 planes can be seen:There is Lateral wedging in the coronal plane seen here by a greater distance between the ribs in the picture on the left compared to the picture on the right.Anterior/posterior wedging in the sagittal plane seen here by a wider posterior vertebral body in the picture on the left compared to the picture on the right.Rotational deformity in the horizontal plane seen here by the arc from the spinal process to the vertebral body in the picture on the left compared to the picture on the right.- These features of the vertebral deformation match perfectly with the 3 dimensional patterns seen in scoliotic spinal deformity.
- The lateral wedging can be seen in the coronal plane when looking at a PA x-ray. - It is evidenced by rib deformity. Since the bone defect is located in the postero-lateral part of the vertebra, where the heads of two ribs articulations, a loss of the height in this region will result in a decreased distance between the ribs in the concave side, visible on the frontal x-ray. - The rib deformity is associated to differences in the rib vertebral angle in the thoracic region.- The rib deformity is the consequence of the vertebral body deformation and a major bony deformation is considered a bad prognosis factor which may also indicate high progression risk.
- The anterior/posterior wedging is found in the sagittal plane.- It results in modification of the sagittal spinal profile typically seen in idiopathic scoliosis provoking reduction of the lateral curves: HypokyphosisHypolordosis Flat back
- The rotational deformity is found in the horizontal plane.- The vertebra presenting the rotational deformity prescribes an arc from the spinous process through the vertebral body. This provides evidence that it is not a mechanical rotation but a real bone deformation.- The rotation in the rest of the spine characteristically seen in scoliosis is a disorientation as a result of this primary rotational deformity.- This means that the reduction of the rotation in scoliosis is related to the correction of the localised rotational deformity.- The changes in kyphosis and lordosis curves in the sagittal plane and the vertebral rotation give an indication as to the degree of bone deformity and therefore the risk of progression. - These factors may not initially be related to the frontal Cobb angle magnitude but provide evidence of high progression risk in an immature spine.
- Another important concept to be highlighted is that the initial localised 3-dimensional vertebral deformity follows a pattern being specifically confined to one vertebra, plus the half of the vertebra above and plus half of the vertebra below.- The vertebral deformity is localised at or around the apex of the primary structural curve.
- The bone deformity is confined to 3 vertebral levels.- As a consequence of this deformation the rest of the vertebrae are disorientated but they are not deformed.
- Once the localised 3 dimensional vertebral deformity is significant enough it provokes the destabilisation of the whole spine.
- The destabilisation of the spine is the consequence of the 3-dimensional vertebral deformity and may result in 1 or more curves.- The primary structural curve is always the one containing the deformed vertebrae and has the greatest potential to progress.- The secondary compensatory curve is a result of the vertebral disorganization produced by the localised vertebral deformity and has a limited potential to progress.- Note that the first curve in early development is not necessarily the primary structural curve. - The secondary compensatory curve can be the first curve to appear however it will never contain the deformed vertebrae.
- The curves developed as a consequence of the 3-dimensional destabilisation of the spine provokes changes in the patient’s posture.
- The postural disorganization is closely related to the type of curve and always follows the same pattern. - This fact permits to get an indirect 3-diemnsional evaluation of the scoliosis curve since the postural evaluation can be evaluated in the 3 planes of the space.- In addition, the pronounced postural disorganization contributes to the aggravation of the curve which makes treating the postural disorganization essential as a fundamental part of the scoliosis conservative management.
- The destabilisation of the spine and the subsequent postural disorganisation will provoke the dysfunction of the neuro-muscular-skeletal system contributing and resulting in scoliosis.- Once a curve is over 20º Cobb angle, mechanical factors and resulting dysfunction of the neuromuscular system together with hormonal regulation of growth velocity can play a very significant role in rapidly progressing scoliotic curves.
- The postural disorganisation affects the orientation of the whole skeleton including the shoulder girdle, the rib cage, the pelvis girdle and the lower limbs, affecting the gait as well.- The pelvis orientation in the 3 planes of the space must be carefully evaluated since it is affected by the destabilisation of the spine. The pelvis may be tilted, rotated or in anteversion or retroversion as a consequence of the spinal disorientation.
- The normal functioning of the muscular system is also affected by the spinal disorientation and the postural disorganization.- The muscles attached to the disoriented spine have their length; strength and direction altered. - Muscles are shorter on the concave side of the curve and longer on the convex side of the curve.- As a result of this, muscles can not actively work to correct the progressing deformity.
- When the movements are abnormal, the sensory information supplied by the ligaments, muscles and joint capsules to the Sensory Cortex in the brain is abnormal. This in turn supplies abnormal information to the Motor Control Centers which will send out abnormal responses back to the spinal muscular system, reinforcing the postural disturbance. This establishes one of the vicious circles in scoliosis that must be broken to succeed with conservative treatment.-Scoliosis patients never feel crooked despite the fact that they have abnormal posture and movement. This is because ascoliosis develops gradually and the motor control centers have time to adapt to the information received from the peripheral receptors and they accept that information as valid.- It is essential to change the information received by the peripheral receptors so that the motor control centres can produce different responses in order to correct the patient’s postural disorganization. -The new movement strategy created will be integrated over time providing sustainable long term improvement of curves and permanent stable changes to patient’s posture.
Once the scoliosis is established, it progresses while ever growth potential remains. This is not due to the genetic fault affecting the vertebral growth because this is only temporary occurring at the start of the scoliosis and so no longer exists. - The reason for this is that the vertebra growth modulation is affected by the asymmetric biomechanical growth plate loading as it is explained by the vicious circle described by Dr. Ian Stokes, shown on the left upper corner of the slide.
- Dr. Stokes’ vicious cycle describes that once the scoliosis is established the asymmetrical loading of the vertebral growth plates due to the biomechanical forces action results in an asymmetrical vertebral growth, which increases the vertebral wedging increasing the spinal curvature. An increased spinal curvature will lead to further asymmetrical loading, and so the Cycle will continue.
The asymmetrical vertebral growth due to the asymmetrical loading of the growth plates is explained by the Hueter-Volkmann principle.This principle establish that compressive forces tend to inhibit skeletal growth, while distractive forces tend to accelerate growth.Scoliosis deformity hold pressure on the curve concavity which do not allow vertebrae to growth properly.Heuter-Volkman principle has been traditionally used to support the corrective action of rigid brace treatment. However, it has been demonstrated that distraction forces alone are not enough to stimulate bone growth and therefore to get a true bone deformation correction.Dynamic loads, altering compression and decompression are required for bone growth stimulation.
The fundamental research have proven that the bone growth is stimulated by the alternation of compression and decompression. It has been also been proven that the pure distraction does not stimulate the bone growth. This research supports the principle that dynamic loading of the spine is essential for vertebral growth stimulation for a true scoliosis correction.
- An understanding of the aetiology of idiopathic scoliosis identifies that to succeed with the conservative treatment of scoliosis it is necessary to have an impact on the vertebral growth modulation by allowing the vertebral side which is deficient in growth to catch up with the side that is growing normally.- Therefore the curve opening needs to be focused at the level of the initial localised 3-dimensional vertebral deformity. - The vertebral growth plate dynamic loading is essential to get a true correction. The continuous and sustained action of the distractive and compressive forces on the vertebral growth plates obtained by the action of the Corrective Movement stimulates the vertebral growth at the level of the localised 3-dimensional vertebral deformity. - It has been recognised with research that static opening merely stops progression and does not facilitate true correction.