Periodic Reporting for period 1 - SPINE (SPinal INnovation Europe; The development of a porous, titanium implant for the treatment of vertebral fractures)
Période du rapport: 2020-10-01 au 2021-09-30
Vertebral compression fracture (VCF) is one of the most common degenerative conditions affecting the spine. A VCF occurs when a vertebra in the spinal column fractures or collapses. It is often due to osteoporosis and low bone density in older patients, but it can also be caused by trauma, tumor or other bone diseases. Patients with mild compression fractures may not develop significant pain, at least not enough to warrant medical evaluation. However, severe fractures with a height loss of 40% or more in the vertebral body are usually painful. Patients with VCFs often experience severe back pain that may limit mobility and lead to disability (Gold, 1996), and subsequently increase mortality in an already vulnerable elderly population (Beall, 2020; Kado et al., 1999). Back pain due to VCFs may also result in decreased exercise tolerance and increased kyphosis development that may reduce abdominal movement, leading to respiratory and abdominal restrictions that may give rise to early satiety and weight loss. Sleep disorders may also occur. In addition, VCFs result in loss of overall body height and angulation deformity whereby the spinal column at the point of fracture becomes abnormally bent, usually forward. This often results in significant postural changes, which can lead to more pain due to muscle spasm, and other adverse compensatory adjustments. Patients can lose self-esteem (they may become fearful of further fractures, have a distorted body image and a perception of poor health) and develop mental disorders like depression, and as a result, self-care may become difficult.
Due to back pain and/or neurologic compromise VCF is a high impact disease with significant societal and economic costs (Wong et al., 2013)). The economic costs of osteoporotic fractures include direct costs of hospitalization and aftercare, and indirect costs attributable to the impact that the fracture has on daily life activities including working days. These costs impose a huge financial burden on health care and social services.
Due to back pain and/or neurologic compromise VCF is a high impact disease with significant societal and economic costs (Wong et al., 2013)). The economic costs of osteoporotic fractures include direct costs of hospitalization and aftercare, and indirect costs attributable to the impact that the fracture has on daily life activities including working days. These costs impose a huge financial burden on health care and social services.
The innovation project consisted in the development of a spinal implant and the associated surgical toolset (VCFix Spinal System) for treating VCF without use of cement. After optimizing the design of the device, a number of pre-clinical tests have been completed or planned to verify and validate the product, as preparation for Regulator submission processes. The specific work and achieved results are outlined in the sections below:
Final prototype of the VCFix implant
The design of the VCFix implant has been optimized and is currently characterized by an expandable structure made of titanium alloy with opening mechanism that allows for angular expansion of the implant, which is expected to restore both height and kyphotic angle of the treated vertebrae. Moreover, a pedicle screw-like fixation system has been incorporated, which allows to fixate the implant within the pedicles of the vertebra. This will prevent subsidence of the implant in the trabecular bone of the vertebra as well as increase the rotational stability of the device.
Development of customized VCFix surgical toolset
A dedicated surgical toolset kit has been created in order to easily access the vertebral body through a bilateral transpedicular approach, and to accurately control the insertion and expansion of the implant during surgery, minimizing chances of unsuccessful implantation. The developed toolset also includes suitable tools to perform posterior fixation surgeries.
Functionality testing
To assess the functionality of the VCFix Spinal System, when the implant is used both as stand-alone or with posterior fixation, a functionality testing protocol was established. Functionality tests of VCFix in stand-alone configuration have been finalized, whereas tests of VCFix combined with posterior fixation instrumentation are ongoing. Briefly, the protocol consists of the following steps: dissection of cadaveric human vertebrae; fracture generation in individual vertebral segments; performance of the proposed surgical procedure using the VCFix implant and toolset; mechanical testing of operated vertebrae to evaluate the implant performance upon physiological loading; micro-CT imaging to compare relevant anatomical parameters i.e. vertebral heights and kyphotic angle at each phase of the testing protocol; percentage of vertebral height decrease after loading; subsidence of the device after loading.
Finite Element Modeling (FEM)
A series of FEM simulations were performed to assess the relevant mechanical properties of the VCFix device. As there are no specific standards for vertebral compression fracture devices, simulations were implemented according to a number of existing ASTM standards applicable to either intervertebral body fusion device assemblies, spinal fixation systems components or metallic bone screws. Specifically, the ASTM standard F2077 (intervertebral body fusion devices) was used for simulating compression and compression - shear tests; the ASTM standard F2193 (spinal fixations) was used for the bending test simulation, while the ASTM standard F543 (metallic bone screws) was used for the simulation of both pull-out and torsion tests.
Final prototype of the VCFix implant
The design of the VCFix implant has been optimized and is currently characterized by an expandable structure made of titanium alloy with opening mechanism that allows for angular expansion of the implant, which is expected to restore both height and kyphotic angle of the treated vertebrae. Moreover, a pedicle screw-like fixation system has been incorporated, which allows to fixate the implant within the pedicles of the vertebra. This will prevent subsidence of the implant in the trabecular bone of the vertebra as well as increase the rotational stability of the device.
Development of customized VCFix surgical toolset
A dedicated surgical toolset kit has been created in order to easily access the vertebral body through a bilateral transpedicular approach, and to accurately control the insertion and expansion of the implant during surgery, minimizing chances of unsuccessful implantation. The developed toolset also includes suitable tools to perform posterior fixation surgeries.
Functionality testing
To assess the functionality of the VCFix Spinal System, when the implant is used both as stand-alone or with posterior fixation, a functionality testing protocol was established. Functionality tests of VCFix in stand-alone configuration have been finalized, whereas tests of VCFix combined with posterior fixation instrumentation are ongoing. Briefly, the protocol consists of the following steps: dissection of cadaveric human vertebrae; fracture generation in individual vertebral segments; performance of the proposed surgical procedure using the VCFix implant and toolset; mechanical testing of operated vertebrae to evaluate the implant performance upon physiological loading; micro-CT imaging to compare relevant anatomical parameters i.e. vertebral heights and kyphotic angle at each phase of the testing protocol; percentage of vertebral height decrease after loading; subsidence of the device after loading.
Finite Element Modeling (FEM)
A series of FEM simulations were performed to assess the relevant mechanical properties of the VCFix device. As there are no specific standards for vertebral compression fracture devices, simulations were implemented according to a number of existing ASTM standards applicable to either intervertebral body fusion device assemblies, spinal fixation systems components or metallic bone screws. Specifically, the ASTM standard F2077 (intervertebral body fusion devices) was used for simulating compression and compression - shear tests; the ASTM standard F2193 (spinal fixations) was used for the bending test simulation, while the ASTM standard F543 (metallic bone screws) was used for the simulation of both pull-out and torsion tests.
To date, the most common treatments for VCF are vertebroplasty and balloon kyphoplasty. These operations, which include reinforcement of the fractured vertebra with bone cement, provide ease of use, minimal invasiveness, high relief of pain in a short amount of time, and stability. However, despite all benefits, these operations have relatively high risk of serious adverse events for patients, of which many are associated to the use of cement.
Up to date, the obtained results are promising and show that VCFix has a performance at least comparable to gold standard treatments with greater stability upon application of physiological loading, but with no use of bone cement. In addition, the device is capable of angular expansion from endplate to endplate of the vertebral body, possibly preventing trabecular bone fracture and ensuring proper height restoration. To comply with the standard practice, VCFix can also be combined with instrumentation for posterior fixation if greater stability is deemed beneficial by the physician, generally providing the option of greater maintenance of the sagittal balance, greater vertebral height correction, and preventing secondary VCF. As a result, it is expected that serious complications are avoided, and that patients regain their initial functionality and experience none to minimum pain.
In summary, the development of VCFix is “in the best interest of patients” for the following reasons:
Faster and less complicated operation
The operation to implant the VCFix device is as follows: a pair of implants is inserted into the vertebra through a transpedicular approach in a minimally invasive surgery. The height of the implant is adjusted to allow intraoperative reduction of fracture and in situ correction of the vertebral height and the angle between the rostral and caudal bony plates of the vertebra. To date, VCFix is the only treatment for vertebral compression fractures that offers mechanical support to the fractured vertebral body and the spinal column without using PMMA bone cement. Since there is no cement injection step in the proposed procedure, the surgery takes less time and is likely to have fewer complications.
Up to date, the obtained results are promising and show that VCFix has a performance at least comparable to gold standard treatments with greater stability upon application of physiological loading, but with no use of bone cement. In addition, the device is capable of angular expansion from endplate to endplate of the vertebral body, possibly preventing trabecular bone fracture and ensuring proper height restoration. To comply with the standard practice, VCFix can also be combined with instrumentation for posterior fixation if greater stability is deemed beneficial by the physician, generally providing the option of greater maintenance of the sagittal balance, greater vertebral height correction, and preventing secondary VCF. As a result, it is expected that serious complications are avoided, and that patients regain their initial functionality and experience none to minimum pain.
In summary, the development of VCFix is “in the best interest of patients” for the following reasons:
Faster and less complicated operation
The operation to implant the VCFix device is as follows: a pair of implants is inserted into the vertebra through a transpedicular approach in a minimally invasive surgery. The height of the implant is adjusted to allow intraoperative reduction of fracture and in situ correction of the vertebral height and the angle between the rostral and caudal bony plates of the vertebra. To date, VCFix is the only treatment for vertebral compression fractures that offers mechanical support to the fractured vertebral body and the spinal column without using PMMA bone cement. Since there is no cement injection step in the proposed procedure, the surgery takes less time and is likely to have fewer complications.