Role of 3D Printing in Surgical Planning

3D printing, or additive manufacturing, has become a crucial technology in surgical planning, allowing for the creation of precise, patient-specific models, guides, and implants. Different 3D printing technologies, each using various materials, offer unique advantages that can be tailored to specific surgical needs. Understanding these technologies and materials is key to optimizing your Virtual Surgical Planning (VSP) process.

Stereolithography (SLA)

Stereolithography (SLA) is widely used in the medical field for producing detailed and smooth anatomical models and surgical guides. SLA printers, like the Formlabs Form 4B, use a laser to cure liquid resin layer by layer.

Materials:

• Standard Resins: These are general-purpose resins that provide good detail and surface finish but are not biocompatible.

• Biocompatible Resins: Specifically formulated for medical use, these resins can be sterilized and used in the operating room. Examples include Surgical Guide Resin, which is designed for making accurate surgical guides.

• Elastic and Flexible Resins: These materials are used when a degree of flexibility is needed, such as in creating soft tissue models. The precision and material compatibility of SLA make it ideal for creating surgical guides that must fit the patient's anatomy perfectly.

Fused Deposition Modeling (FDM)

Fused Deposition Modeling (FDM) involves extruding thermoplastic filament through a heated nozzle, which is then deposited layer by layer. FDM is cost-effective and easy to use, though it typically produces lower resolution prints compared to SLA.

Materials:

• PLA (Polylactic Acid): A biodegradable thermoplastic often used for educational models or prototypes.

• ABS (Acrylonitrile Butadiene Styrene): A durable plastic commonly used for mechanical parts and functional prototypes. PETG- (Polyethylene Terephthalate Glycol): A tough, chemical-resistant plastic that combines some of the advantages of PLA and ABS. FDM is typically used for creating preliminary models or practice runs rather than final surgical guides.

Selective Laser Sintering (SLS)

Selective Laser Sintering (SLS) uses a laser to fuse powdered material, such as nylon or metal, into solid parts. SLS is known for its ability to produce strong, durable models without needing support structures.

Materials:

• Nylon: A strong, flexible plastic often used for durable models and complex geometries.

• Alumide (Nylon mixed with Aluminum powder): Provides a metallic appearance and increased strength for functional prototypes.

• Medical-Grade Nylon: Biocompatible materials that can be used for implants or long-term in vivo applications. SLS is particularly useful when strength and durability are required, such as in custom implants or robust surgical models.

Digital Light Processing (DLP)

Digital Light Processing (DLP) is similar to SLA but uses a digital light projector screen to cure an entire layer at once, making it faster than SLA for certain applications.

Materials:

• Standard and Biocompatible Resins: Similar to those used in SLA, offering options for high detail and medical use.

• Ceramic-Filled Resins: Used for creating parts with ceramic-like properties, useful in specialized applications. DLP is favored for quick production of detailed models, particularly when speed is crucial.

How 3D Printing Factors into Surgical Planning

The choice of 3D printing technology and materials in surgical planning depends on the specific requirements of the case. For detailed and accurate surgical guides, SLA printing with biocompatible resin is often the best choice due to its precision and material suitability for medical applications. If the goal is to produce a quick prototype or educational model, FDM printing with PLA or ABS might be more appropriate due to its cost-effectiveness and ease of use.

Understanding the strengths, limitations, and material options of each 3D printing technology allows you to make informed decisions tailored to your specific surgical needs. While this course will primarily focus on SLA printing due to its relevance in creating surgical guides, we encourage you to explore other 3D printing methods and materials as your experience and requirements grow.