Custom-Made Titanium 3-Dimensional Printed Interbody Cages for Treatment of Osteoporotic Fracture–Related Spinal Deformity

doi:10.1016/j.wneu.2017.11.160

World Neurosurgery

Volume 111, March 2018, Pages 1-5

https://doi.org/10.1016/j.wneu.2017.11.160 Get rights and content

Background

Advances in minimally invasive interbody fusion have greatly enhanced surgeons' capability to correct adult spinal deformity with reduced morbidity. However, the feasibility of such approaches is limited in patients with previous osteoporotic fractures as the resultant vertebral deformity renders the end plate geometry incongruous with conventional interbody implants. Current 3-dimensional (3D) printing technology offers a novel solution by fabricating custom-made implants tailored to individual anatomy. We present the results of a patient with osteoporotic lumbar fractures treated by such technology.

Case Description

A 74-year-old woman, with previous osteoporotic fractures at L2 and L3 resulting in concave deformity of the end plates, presented with intractable radiculopathy secondary to lateral recess and foraminal stenosis (L2-3 and L3-4). A minimally invasive lateral lumbar interbody fusion at L2-3 and L3-4 was considered favorable, but due to the associated vertebral collapse, off-the-shelf implants were not compatible with patient anatomy. In silico simulation based on preoperative computed tomography (CT) imaging was thus conducted to design customized cages to cater for the depressed recipient end plates and vertebral loss. The design was converted to implantable titanium cages through 3D additive manufacturing. At surgery, a tight fit between the implants and the targeted disk space was achieved. Postoperative CT scan confirmed excellent implant–end plate matching and restoration of lost disk space. The patient began to ambulate from postoperative day 1 and at 6-month follow-up resolution of radicular symptoms and CT evidence of interbody fusion were recorded.

Conclusions

3D-printed custom-made interbody cages can help overcome the difficulties in deformity correction secondary to osteoporotic fractures.

Introduction

Interbody fusion is the workhorse for treatment of degenerative disease of the lumbar spine. It provides a powerful means to correct deformity and achieve nerve root decompression through restoration of lost disk space with implantation of interbody cages. In recent years the benefits of such approach have been enhanced by minimally invasive lateral techniques allowing placement of cages that can span the entire vertebral end plates. Such laterally inserted cages have distinctively large footprints and bilateral contact with the dense apophyseal rings of the end plates. They provide increased rigidity and improvement in end plate–implant contact and help distribute load over a broader area,¹ thus reducing the risk of graft subsidence, particularly in osteoporotic patients.2, 3

However, a major challenge for applying interbody fusion for treatment of osteoporotic patients is the prevalence of preexisting vertebral collapse and end plate deformity at the target segments. Such vertebral deformation can often lead to significant mismatch between the contour of the cage and the disk space, thus compromising the resultant end plate–implant contact and stability. This is particularly problematic for laterally inserted cages as the loss in conformity is more acute for cages that are designed to cover a large expanse of the end plate than for those that make contact with only a small portion of it. Conceivably, such incongruity can significantly limit the application of lateral lumbar interbody fusion (LLIF) despite its conceptual benefits for this target population.

In recent years breakthrough in fabricating prosthesis with a 3D printer has drastically reduced the logistics of manufacturing custom-made implants—by depositing materials in layers to produce a 3D object according to a digital print file, 3D printing can effectively create an object in any shape or form and offers an ideal solution for accommodating the geometric complexity of individual prosthetic requirement that would otherwise be incompatible for conventional, off-the-shelf products.⁴ Specifically, for patients with previous osteoporotic fractures, the technology can help circumvent the obstacles of implant mismatch by fashioning 3D-printed interbody cages optimally shaped to the desired segmental contour and footprints that match accurately the recipient end plates.

To date there have been few case reports describing the application of 3D printing technology for treatment of vertebral tumor and anomaly.5, 6, 7, 8, 9, 10 To our knowledge no report has yet existed on its application in lumbar interbody fusion for degenerative disease or trauma. We therefore presented in this report the clinical details and results of applying such technology in a patient with previous osteoporotic fractures in which custom-made 3D-printed cages were successfully applied to address the associated spinal deformity. This study was carried out with local human research ethics committee approval.

Section snippets

Case Description

A 74-year-old female presented with intractable right L2 and L3 radicular pain secondary to degenerative scoliosis. She had previous osteoporotic compression fractures at L2 and L3 (Figure 1) resulting in longstanding type III concave collapse.¹¹ She had previously undergone an L4-5 interbody fusion for degenerative spondylolisthesis. Her past medical history included rheumatoid arthritis and peripheral neuropathy managed with long-term corticosteroid and methotrexate. Physical examination

Discussion

Patients with significant spinal deformity and previous osteoporotic fractures present a unique challenge to spine surgeons. While conventional vertebral column resection and reconstruction provide an ultimate solution to address vertebral deformity and malalignment, the magnitude of such endeavors poses a major surgical burden to the frail elderly osteoporotic patients.13, 14 In recent years, advances in interbody fusion techniques have provided a viable alternative to address adult spinal

Conclusions

The present report demonstrates for the first time the success and potential of applying 3D printing technology in LLIF—3D-printed cages provided a novel solution for addressing adult spinal deformity and osteoporotic vertebral collapse with favorable radiographic and clinical outcome. Our results support wider application of such technology.

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: Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Case ReportCustom-Made Titanium 3-Dimensional Printed Interbody Cages for Treatment of Osteoporotic Fracture–Related Spinal Deformity

Background

Case Description

Conclusions

Introduction

Section snippets

Case Description

Discussion

Conclusions

Surgery

Biomechanics of lateral lumbar interbody fusion constructs with lateral and posterior plate fixation: laboratory investigation

J Neurosurg Spine

Radiographic and clinical evaluation of cage subsidence after stand-alone lateral interbody fusion

J Neurosurg Spine

Biomechanics of lateral interbody spacers: going wider for going stiffer

Sci World J

Medical applications for 3D printing: current and projected uses

P T

The utility of 3D printing for surgical planning and patient-specific implant design for complex spinal pathologies: case report

J Neurosurg Spine

Multi-level 3D printing implant for reconstructing cervical spine with metastatic papillary thyroid carcinoma

Spine (Phila Pa 1976)

Sacral Reconstruction with a 3D-printed implant after hemisacrectomy in a patient with sacral osteosarcoma: 1-year follow-up result

Yonsei Med J

Reconstruction of the thoracic spine using a personalized 3D-printed vertebral body in an adolescent with a T9 primary bone tumour: case report

World Neurosurg

Reconstruction of the upper cervical spine using a personalized 3D-printed vertebral body in an adolescent with ewing sarcoma

Spine (Phila Pa 1976)

Case Report
Custom-Made Titanium 3-Dimensional Printed Interbody Cages for Treatment of Osteoporotic Fracture–Related Spinal Deformity