SCOLI Co-Director Dr. D. Kojo Hamilton shares critical insights on avoiding iatrogenic cervical deformities and optimizing patient outcomes through comprehensive surgical planning at the Seattle Science Foundation.
Presentation Overview
Dr. D. Kojo Hamilton, Co-Director of the Spine Computational Outcomes Learning Institute (SCOLI) and Professor of Neurological Surgery at the University of Pittsburgh, delivered an educational presentation at the Seattle Science Foundation focusing on avoiding iatrogenic cervical deformities—conditions inadvertently created during surgical intervention.
The talk emphasized the importance of understanding cervical spine biomechanics, comprehensive preoperative planning, and recognizing when surgical intervention may create more problems than it solves.
Key Topics Covered
Dr. Hamilton defined cervical deformity as any abnormality in the alignment, shape, or formation of the cervical vertebral column, with etiologies including:
- Degenerative disease
- Neuromuscular disorders
- Congenital conditions
- Iatrogenic causes (post-laminectomy syndrome, post-fusion syndrome)
Biomechanical Considerations
The cervical spine presents unique biomechanical challenges:
- Six degrees of freedom: Flexion, extension, lateral bending, rotation, and anterior-posterior translation
- Load distribution: Posterior elements carry approximately two-thirds of axial load versus one-third for the intervertebral disc and body
- Kyphotic cascade: Loss of lordosis shifts the center of mass, increasing bending moments and axial load anteriorly, leading to progressive worsening
Impact on Quality of Life
Cervical deformity carries a disease burden comparable to chronic emphysema and near-blindness, significantly affecting patient quality of life through:
- Neck pain and neurological deficits
- Myeloradiculopathy syndromes
- Dysphagia (swallowing difficulties)
- Respiratory complications
- Lower back pain due to compensatory mechanisms
Critical Measurements and Assessment
Modern Cervical Spine Evaluation
Dr. Hamilton emphasized that the cervical spine cannot be evaluated as a standalone region. Key measurements include:
- C2-C7 SVA (Sagittal Vertical Axis): Measures anterior-posterior shift of cervical alignment
- T1 Slope: A critical parameter for determining required cervical lordosis
- Chin-Brow Vertical Angle: Affects how patients perceive their environment and maintain horizontal gaze
The T1 Slope Relationship
The relationship between T1 slope and required cervical lordosis is fundamental:
- Smaller T1 slope requires smaller cervical lordosis to maintain horizontal gaze
- Larger T1 slope requires greater lordosis
- Thoracic kyphosis directly impacts cervical compensation requirements
Classification Systems
Dr. Hamilton advocated for the Ames ISSG classification system, which categorizes deformities by:
Primary Deformity Descriptor:
- C: Cervical (primary sagittal deformity with apex in cervical spine)
- CT: Cervicothoracic
- T: Thoracic primary sagittal deformity
- Coronal deformities (most challenging to treat)
- Craniovertebral junction deformities
Modifiers:
- Cervical SVA (less than 4 cm threshold)
- Horizontal gaze positioning
- Cervical lordosis minus T1 slope (goal: less than 15 degrees)
- Myelopathy presence
- Thoracolumbar Schwab classification integration
Surgical Considerations
Patient Selection and Optimization
Before any deformity surgery, comprehensive assessment is essential:
- Physiological age and frailty assessment
- Bone density evaluation (opportunistic CT, DEXA scan)
- Flexibility versus rigidity of deformity (dynamic imaging)
- General health status and surgical invasiveness scale
- Nutritional optimization (pre-albumin levels)
Surgical Approaches
Dr. Hamilton outlined approach selection based on deformity characteristics:
Flexible Deformities:
- Anterior cervical corpectomy and discectomy fusion (ACDF)
- Limited to flexible cases without rigid posterior elements
- Best for focal kyphosis with mid-cervical apex
Rigid Deformities:
- Posterior column osteotomies (PCO)
- Pedicle subtraction osteotomies (PSO)
- Combined anterior release with posterior instrumentation
- Required for cervicothoracic junction deformities and chin-on-chest presentations
Specific Technique Considerations
- Posterior column releases: Three-level interlaminar decompression protecting neurovascular elements
- Complete visualization: Essential before cantilevering to avoid postoperative radiculopathy
- Nerve root decompression: Critical when performing closed-wedge osteotomies
- CSF leak management: Small durotomies should be addressed immediately to maintain buoyancy and assess adequate decompression
Critical Safety Principles
The Danger of “Negative Persistence”
Dr. Hamilton strongly emphasized avoiding “negative persistence”—continuing surgery when goals are not being met or complications arise:
“If you plan on staging a big cervical deformity, any deformity, any surgery, and they don’t align with your goals… restaging the minor inconvenience of closing and coming back versus persisting… What matters is what you’re doing right there.”
Pause Events:
- Uncontrolled CSF leak requiring 4+ hours to repair
- Excruciating blood loss (2+ liters before completing deformity correction)
- Major vessel injury
- Tracheoesophageal injury
- Inadequate surgical team or support staff
Preoperative Planning Essentials
- Team preparation: No cervical deformity is emergent—use the 3+ weeks of scheduling to prepare the entire team
- Co-pilot identification: Know who can assist with complex cases
- Avoid overlapping surgeries: Not appropriate for major deformity cases
- Patient substrate optimization: Address smoking, bone quality, nutrition well before surgery
Special Considerations: Dropped Head Syndrome
For patients with chin-on-chest deformity:
- Differential diagnosis: Rule out neuromuscular disorders, vitamin deficiency, isolated neck extensor myopathy
- Swallowing assessment: Pre-operative evaluation essential
- Feeding tube consideration: Discuss PEG/G-tube placement for emaciated patients or those with significant dysphagia
- Staging: Often requires anterior release followed by posterior osteotomies
- Nutritional optimization: May require 1 month of pre-operative feeding optimization
Complications and Outcomes
Realistic Complication Rates
- 2-3% mortality rate
- Major medical complications
- Neurological deficits
- Dysphagia and hoarseness (common)
- Hardware failure
Successful Outcomes
When properly executed with appropriate patient selection and alignment goals:
- Significant improvement in quality of life
- Restoration of horizontal gaze
- Reduction in compensatory pain mechanisms
- Improved patient self-perception and social function
Key Takeaways
Prevention is Paramount:
Many iatrogenic cervical deformities are preventable through:
- Thorough preoperative assessment (anatomical, biomechanical, physiological)
- Understanding whole-spine alignment principles
- Avoiding unnecessary laminectomies in at-risk patients
- Recognition of neuromuscular disorders
Comprehensive Planning:
- Obtain standing radiographs and full-spine imaging (EOS) before simple ACDF procedures
- Understand how current surgery may affect future alignment
- Optimize patient substrate before surgery
- Prepare entire surgical team well in advance
Know Your Limits:
- Partner with experienced surgeons for complex cases
- Don’t hesitate to stage procedures
- Abandon negative persistence
- Ensure adequate support staff and resources
Educational Resources
Dr. Hamilton’s previous presentations on cervical deformity are available on SSFTV:
- 2023 presentation
- 2024 presentation
- Case examples and surgical techniques
About the Speaker
D. Kojo Hamilton, M.D.
- Co-Director, Spine Computational Outcomes Learning Institute (SCOLI)
- Professor of Neurological Surgery, University of Pittsburgh
- Residency Program Director, Department of Neurological Surgery
- Director and Chief of Spine, UPMC
- Board Certified in Neurological Surgery
- Fellow, American Association of Neurological Surgeons
- Member, Scoliosis Research Society
Dr. Hamilton specializes in complex spine surgery, including scoliosis, adult spinal deformity, trauma, and revision spine surgery. His research focuses on advancing spine education through technology-driven approaches and biomechanical understanding.
About Seattle Science Foundation
The Seattle Science Foundation is a non-profit organization dedicated to advancing the quality of patient care through education, research, innovation, and technology. Through their international communication platform, they bring together medical and scientific communities from around the world, providing cutting-edge continuing medical education and fostering groundbreaking advancements in medicine.
Presentation Date: October 6, 2025
Location: Seattle Science Foundation, Seattle, WA
Video: Available on SSFTV YouTube Channel
