Preoperative Surgical Planning in 3D

From Medical Imaging to Personalized Surgery

Preoperative surgical planning in three dimensions (3D) is a relatively recent but transformative development in modern medicine. Instead of relying solely on two dimensional (2D) medical images and intraoperative decision making, surgeons can now plan complex procedures in advance, based on an accurate, patient-specific 3D representation of anatomy.

This approach fundamentally changes how surgery is prepared, communicated, and executed.

What Is 3D Preoperative Surgical Planning?

3D preoperative planning is a structured process in which the surgeon, together with a multidisciplinary support team, prepares the surgical procedure before entering the operating room.

Using CT or MRI data, the patient’s anatomy is reconstructed into a digital three-dimensional model. Together, the surgeon, radiologist, and medical designer define:

• Surgical access paths

• Entry angles and trajectories

• Cutting planes and drilling directions

• Distances, depths, and safety margins

• Implant positioning and fixation strategies

The result is a clear, shared surgical plan tailored to the specific anatomy of the individual patient.

Why this matters: Planning surgical steps in advance reduces uncertainty, improves accuracy, and allows the surgical team to focus on execution rather than improvisation.

The Role of Preoperative Simulation

The primary goal of preoperative simulation is to allow the surgeon to prepare as thoroughly as possible for the upcoming procedure.

By working with a 3D digital model, or a physical anatomical replica, the surgical team can:

• Understand exactly what will be encountered during surgery

• Anticipate technical challenges before they occur

• Reduce stress and cognitive load in the operating room

• Improve communication within the surgical team

• In some cases, explain the procedure more clearly to the patient

Simulation turns surgery from a reactive process into a controlled, well rehearsed intervention.

How Preoperative Planning Is Performed

There are two main complementary approaches:

1. Digital Planning (VR / AR / 3D Software)

Using advanced 3D planning tools, the medical designer prepares a digital environment where the surgeon can:

• Inspect anatomy from any angle

• Create cross-sectional views

• Hide or isolate specific structures

• Simulate cuts, resections, or implant placement

• Explore multiple surgical strategies before choosing the optimal one

  
  

Virtual and augmented reality systems further enhance spatial understanding, especially in anatomically complex regions.

2. Physical Anatomical Models

Patient-specific anatomical models can be 3D printed using rigid, flexible, transparent, or tissue-mimicking materials.

These models allow surgeons to:

• Cut, drill, or saw manually

• Practice freehand techniques

• Use patient-specific surgical guides

• Test tools and implants physically

  
  

Why physical models matter:Hands-on interaction provides tactile feedback and spatial intuition that even the best screens cannot fully replace.

The Medical Designer: A New Clinical Role

A medical designer (also referred to as a medical device engineer or surgical planner) is a specialist who bridges medicine, engineering, and digital design.

This role requires:

• Advanced 3D digital skills

• Deep anatomical knowledge

• Familiarity with surgical procedures and workflows

• Close collaboration with surgeons

  
  

Medical designers work with specialized software to perform segmentation, the process of converting 2D medical imaging data (DICOM from CT or MRI) into accurate 3D anatomical models.

They then support:

• Digital surgical planning

• Design of patient-specific instruments

• Preparation of anatomical models

• Coordination of 3D printing and post-processing

Digital Surgical Planning: Step by Step

A typical workflow includes:

1. Receiving patient CT or MRI DICOM files

2. Meeting with the surgeon to define surgical goals

3. Clinical analysis (anamnesis): understanding the pathology and objectives

4. Defining surgical approach, tools, and implants

5. Segmentation: converting 2D images into a 3D digital model

6. Joint surgical planning with the surgeon

7. Designing patient-specific instruments (PSI)

8. 3D printing of anatomical models and guides

Once goals are defined, patient-specific tools are digitally designed to match both the anatomy and the surgeon’s exact plan.

Patient-Specific Instruments (PSI)

Patient-Specific Instruments (PSI) are custom surgical guides designed for a single patient and a single procedure.

These may include:

• Cutting guides that define exact resection planes

• Drill guides for precise screw or pin placement

• Marking guides for outlining surgical contours

After surgeon approval, these tools are 3D printed using biocompatible materials, cleaned, sterilized, and delivered to the operating room.

Why PSI matters:They reduce variability, improve precision, and shorten operative time.

Custom Implants and Reconstruction

In some cases, the planning process also includes designing custom implants.

These implants may be manufactured from:

• Titanium (for strength and long-term fixation)

• PEEK (a biocompatible thermoplastic polymer)

Custom implants allow reconstruction that follows the patient’s anatomy precisely—often replacing generic, off-the-shelf solutions.

Clinical Fields Using 3D Preoperative Planning

3D planning and patient-specific tools are used across many medical disciplines, including:

• Orthopedics: deformity correction, fracture reconstruction, scoliosis

• Orthopedic oncology: tumor resection with bone preservation

• Hand surgery: correction of malunited fractures

• Maxillofacial surgery: orthognathic surgery, facial asymmetry, tumor resection, gender-affirming surgery

• ENT and neck surgery: airway and tumor planning

• Neurosurgery: cranial reconstruction and surgical rehearsal

• Cardiothoracic surgery: anatomical models and custom tools

• Cardiology: understanding complex cardiac anatomy

• Vascular surgery: aneurysms and vascular pathologies

• General surgery: liver, kidney, and pancreatic tumors

• Gynecology and obstetrics: anatomical modeling and fetal visualization

Common Software Tools

Segmentation

• 3D Slicer

• Materialise Mimics

• 3D Systems D2P

Digital Planning and Design

• Materialise 3-matic

• Blender

• Autodesk Meshmixer

• Geomagic Freeform

• Rhinoceros 3D

Final Thoughts

Preoperative surgical planning in 3D is not just a technological upgrade, it is a shift in mindset.

By combining medical imaging, digital design, and physical modeling, surgery becomes more predictable, more precise, and more personalized.

The future of surgery is planned, long before the first incision.

Note: An earlier version of this topic was originally authored by me as a Hebrew Wikipedia entry. This article expands and updates that work based on years of hands-on clinical and medical design experience.