Spinal Implants

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Spinal Implants

• Andrew Kohm
• Kyphon Inc.

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Anatomy
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Anatomy
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Anatomy
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Spinal Injury or Deformity

• Birth Defects
• Disease
• Trauma
• Aging

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Clinical Diagnosis

• Patient description
• Amount of pain?
• Type of pain?
• Location?
• During which activities?
• When did the pain start?

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Clinical Diagnosis

• Radiograph

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Clinical Diagnosis

• MRI

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Clinical Diagnosis

• CT

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Clinical Diagnosis

• CT

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Clinical Diagnosis

• CT

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Clinical Diagnosis

• Bone Scan

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Clinical Diagnosis

• Discogram

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Clinical Diagnosis

• FAD

Functional Anesthetic Discography
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Intervertebral Disc Herniation
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Disc Repair
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Non-repairable Disc

• Fusion
• Replacement
• Whole disc
• Nucleus

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Disc Replacement

• Problems
• Materials
• Properties
• Fatigue
• Migration
• Surgical Procedure

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Disc Replacement
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Fusions
Bonegraft Artificial Materials
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Spinal Fusion
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Fusion
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Stabilizing Implants
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Stabilizing Implants
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Stabilizing Implants
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Fusion Radiograph
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Stabilization Radiograph
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Fusion Radiograph
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Fusion Failures

• Does not fuse
• Pedicle screw loosening
• Pedicle screw breaks
• Rod bends
• Rod breaks
• Pedicle breaks
• Vertebral body breaks

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Deformity Correction
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Deformity Correction
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Computer Guided Surgery
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Vertebral Body Replacement
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Osteoporotic Fracture
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Compression Fracture
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Vertebroplasty
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Kyphoplasty
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Post Op
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Cement Fill
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Vertebroplasty vs. Kyphoplasty
Advantages
Lower cost
Height restoration Reduction of adjacent
fractures Safe cement fill
Disadvantages
Uncontained cement fill No height restoration
Higher cost Must be a new fracture
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Burst Fracture
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Burst Fracture
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Spinal Biomechanics
F2400 N M 20 NM
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Spinal Biomechanics
Range of Motion
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Spinal Biomechanics
Disc
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Instant Axis of Rotation
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Functional Spinal Units
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Effect of Testing Parameters
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Spine Tester
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Pedicle Screw System
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Testing
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Compression Plate
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Screw Pullout Resistance

• Fs SAs (SLpDmajor)TSF
• Fs Predicted shear failure force (N)
• S Material ultimate shear stress (MPa)
• As Thread shear area (mm2)
• L Length of thread engagement in material
• Dmajor Major diameter (mm)
• TSF Thread Shape Factor (Dimensionless)
• (0.5 0.5735 d/p)
• d thread depth (mm) (Dmajor Dminor) / 2
• p thread pitch

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Pedicle Screw Fixation
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Screw Angle Effect
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Screw Orientation
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Non Fixed Moment Arm
Fixed Moment Arm
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Biomechanical Testing
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Cadaver Testing
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Testing Problems

• Forces to apply?
• Direction of the forces?
• No supporting ligaments or muscles
• No self-repair
• Limited testing life

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Thank you Contact Information Andrew
Kohm akohm_at_kyphon.com 408.548.6542