Identification of Key Parameters to Initiate the Shift Towards 3D, Dynamic and Mechanically-informed Decision Making in Adolescent Idiopathic Scoliosis
Identification of Key Parameters to Initiate the Shift Towards 3D, Dynamic and Mechanically-informed Decision Making in Adolescent Idiopathic Scoliosis
Adolescent Idiopathic Scoliosis (AIS) is a growth defect of the spine that primarily occurs
 in prepubertal children between the age of 10 to 14 years, affecting approximately 3% of
 these otherwise normal children. AIS has been associated with problems related to posture,
 load-related back pain, as well as aesthetic problems, e.g. the induced asymmetry of the
 shoulder. Therefore, early diagnosis followed by the appropriate treatment is vital to
 prevent further curve progression of AIS and minimize the health-related complications of
 these patients.

 The current treatment recommendation to stop curve progression for an immature patient with a
 scoliosis curve between 25 and 40 degrees is to wear a brace. If the curve in the skeletally
 immature patient is not responding to the brace treatment, dynamic scoliosis correction by
 vertebral body tethering can be considered when there is still some growth potential left.
 State-of-the-art guidelines for the selection of fusion levels are currently mainly based on
 two-dimensional (2D) static radiographic parameters (such as, the Cobb angle and Shoulder
 balance) and a qualitative assessment of 2D bending or traction radiographs. Several
 classification systems and algorithms that are based on the 2D static radiographic (X-ray)
 parameters exist to assist surgeons in determining the appropriate levels to be instrumented.
 Despite this wide range of classification systems and detailed guidelines available in the
 literature, spinal fusion does not always yield satisfying 2D radiographic clinical outcome,
 with revision rates ranging from 3.9% to 22%.

 Overall, the surgeon is presently not provided with 3D dynamic and mechanical information
 regarding the deformity of the AIS to guide the decision-making. Obtaining this vital 3D
 dynamic information regarding the curvature and mechanical behavior of the spine will allow
 the surgeon to make an evidence-based and well-informed decisions in the treatment of the AIS
 patient. Consequently, realizing these objectives has the potential to improve patient
 satisfaction, reduce the postoperative complications and accordingly reduce socio-economic
 costs associated with AIS treatment. Recent advances in the use of subject specific
 musculoskeletal models will form the basis to realize this shift from 2D to 3D dynamic in AIS
 care.
Adolescent Idiopathic Scoliosis (AIS) is a growth defect of the spine that primarily occurs
 in prepubertal children between the age of 10 to 14 years, affecting approximately 3% of
 these otherwise normal children. The spine, which is normally straight in a posterior view,
 forms one or two lateral curves with associated turns around its longitudinal axis, like a
 spiral staircase. AIS has been associated with problems related to posture, load-related back
 pain, as well as aesthetic problems, e.g. the induced asymmetry of the shoulder. Therefore,
 early diagnosis followed by the appropriate treatment is vital to prevent further curve
 progression of AIS and minimize the health-related complications of these patients.

 The current treatment recommendation to stop curve progression for an immature patient with a
 scoliosis curve between 25 and 40 degrees is to wear a brace. If the curve in the skeletally
 immature patient is not responding to the brace treatment, dynamic scoliosis correction by
 vertebral body tethering can be considered when there is still some growth potential left.
 This recent (2019) US Food and Drug Administration (FDA) approved device for tethering
 gradually corrects the scoliosis by slowing growth on the convex side of the curve. This
 technique is minimally invasive, preserves motion, and does not preclude spinal fusion
 surgery when unsuccessful, but at the moment long term results are lacking. When a curve
 reaches 50 degrees, it's clinically expected to further progress and further growth potential
 is low, a "scoliosis fusion" surgery is recommended. This type of surgery permanently
 attaches all vertebrae in the area to be corrected to each other by surgical instrumentation.
 In order to reach the desired surgical outcome, one of the main decisions to be made by the
 treating surgeon is the selection of the appropriate fusion levels (i.e. the upper and lower
 instrumented vertebra). State-of-the-art guidelines for the selection of fusion levels are
 currently mainly based on two-dimensional (2D) static radiographic parameters (such as, the
 Cobb angle and Shoulder balance) and a qualitative assessment of 2D bending or traction
 radiographs. Several classification systems and algorithms that are based on the 2D static
 radiographic (X-ray) parameters exist to assist surgeons in determining the appropriate
 levels to be instrumented. Despite this wide range of classification systems and detailed
 guidelines available in the literature, spinal fusion does not always yield satisfying 2D
 radiographic clinical outcome, with revision rates ranging from 3.9% to 22%. Besides an
 adequate correction of the spinal curve in all three planes, factors such as shoulder level,
 clinical rib and lumbar hump, as well as scar size, play a major role in the evaluation of
 treatment success. This contributes to the fact that spinal fusion in AIS patients is a
 costly procedure. Therefore, the potential limitations of the current state-of-the-art
 surgical decision making should be critically examined and improved where possible.

 There are three main limitations of the state-of-the-art classification systems highlighted
 in the literature. The first limitation is that classification systems use 2D static
 radiographic parameters to provide guidelines for a three-dimensional (3D) deformity of the
 spine. The second limiting factor is that the current classification systems do not include
 dynamic components. Even though, it has been shown that a 2D radiographic assessment is not
 representative of spinal balance during daily life activities. The third limitation is that
 the surgeon has only limited information on the mechanical behavior of the patient's spine.
 Mechanical information of the spine, such as the spine stiffness (i.e. a measure of the force
 required to deform a patient's spine), is critical for the selection of the appropriate
 fusion levels that, for example, would result in balanced shoulders.

 Overall, the above highlighted limitations indicate that the surgeon is presently not
 provided with 3D dynamic and mechanical information regarding the deformity of the AIS to
 guide the decision-making. Consequently, there is an immediate need to overcome this apparent
 gap in the decision-making in AIS by identifying the key parameters that provide the surgeon
 with vital 3D dynamic information regarding the deformity. Obtaining this vital 3D dynamic
 information regarding the curvature and mechanical behavior of the spine will allow the
 surgeon to make an evidence-based and well-informed decisions in the treatment of the AIS
 patient. Consequently, realizing these objectives has the potential to improve patient
 satisfaction, reduce the postoperative complications and accordingly reduce socio-economic
 costs associated with AIS treatment. Recent advances in the use of subject specific
 musculoskeletal models will form the basis to realize this shift from 2D to 3D dynamic in AIS
 care.
Inclusion Criteria:

 -  Patient diagnosed with Adolescent Idiopathic Scoliosis

 -  10-35 years old

 -  Patient is scheduled to be surgically treated at UZ Leuven

 -  Informed consent obtained: also from parent/guardian in case of minors

 Exclusion Criteria:

 -  Patient has undergone a fusion procedure before

 -  Patient has a severe underlying illness which might influence the outcome of the
 surgery

 -  Making it reasonable for the investigator to exclude the patient