Performance comparison between three-dimensionally printed patient-specific drill guides and the conventional free-hand technique for vertebral implant placement in the canine thoracolumbar spine: An ex-vivo study

Guevara, Francisco

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https://hdl.handle.net/2142/115890 Copy

Description

Title

Performance comparison between three-dimensionally printed patient-specific drill guides and the conventional free-hand technique for vertebral implant placement in the canine thoracolumbar spine: An ex-vivo study

Author(s)

Guevara, Francisco

Issue Date

2022-07-08

Director of Research (if dissertation) or Advisor (if thesis)

Foss, Kari D.

Committee Member(s)

• Hauge, Devon W.
• Moran, Clara E.
• Harper, Tisha A.

Department of Study

Vet Clinical Medicine

Discipline

VMS-Veterinary Clinical Medcne

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Dog
• 3D-printing
• Spine
• Surgery

Abstract

Surgical stabilization of the vertebral column is often indicated for dogs with severe myelopathic signs and/or refractory pain secondary to spinal instability. Among various spinal fixation techniques described in the veterinary literature, pin or screw and polymethyl methacrylate (PMMA) constructs are used most commonly. Although this technique is an accepted standard of care, it is technically challenging and can lead to life-threatening complications. Experimental studies in canine cadavers have reported rates of spinal canal breach ranging from 19% to 100%, during bicortical implant placement in the lumbar and cervical spine respectively. Several studies have investigated the application of 3D printed drill guides in the canine spine and have demonstrated the feasibility and safety of this technique. However, these studies focused on a specific region of the spine (cervical, thoracic, or lumbosacral). Additionally, in these studies, only 1-2 individuals performed placement of the implants with a small number of vertebrae evaluated. Further investigation into the utilization of 3D printing techniques over the entire canine spine and their use by surgeons with varying degrees of skillsets are warranted to continue to determine the application and safety. The objective of this study was to compare performance between 3D printed patient- specific drill guides (3DPG) and the conventional free-hand technique (FH) for vertebral implant placement in canine cadaveric thoracolumbar spines. We hypothesized that the use of computed tomography (CT) -based patient-specific vertebral drill guides would result in significantly more accurate placement of bicortical implants in the canine cadaveric spine compared to the conventional free-hand technique. Twenty-four medium-to-large-breed canine cadavers were utilized for this study. CT of each cadaveric spine was performed, and optimal implant trajectories were established for both the left and right sides of the T10 through L6 vertebra. CT data was then used to create patient- specific drill-guides for the vertebrae of interest. Each cadaver was randomly assigned to 1 of 6 veterinarians (two board-certified surgeons, two board-certified neurologists, one surgery resident, and one neurology resident) with varying levels of experience placing vertebral implants. For each cadaver, vertebrae were randomly assigned a surgical order and technique (3DPG or FH) for both right and left sides. Following implant placement, postoperative CT images were acquired, and performance of pin placement was assessed using a modified Zdichavsky classification by a single, blinded observed. A total of 480 implants were placed in 240 vertebrae. Three sites were excluded from analysis due to surgeon error; therefore, a total of 238 implants were placed using the FH technique and 239 implants were placed using 3DPG. When evaluating implant placement, 152/239 (63.6%) of implants were considered to be optimally placed using 3DPG compared to 115/248 (48.32%) with FH. Overall, pin placement using 3DPG was significantly more accurate (P<0.001) compared to the FH technique. This study demonstrates that the use of 3DPG is superior to that of utilizing a free-hand technique in regard to implant accuracy. While 63.6% of implants were scored a Grade I (optimal placement) using the 3DPG technique, 87% were a Grade I or IIa compared to only 69% as Grade I or IIa when placed via FH technique. While Grade I is considered optimal placement, clinically, Grade I or Grade IIa are considered acceptable. This study demonstrated that utilizing 3DPG led to better performance with placing implants in the canine thoracolumbar spine compared to the traditional FH technique and the 3DPG technique was able to be utilized by all surgeons with varying degrees of experience. Additional studies utilizing this technique in a clinical setting are warranted.

Graduation Semester

2022-08

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Francisco Guevara

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