The role of patient-specific instruments in orthopedics

Key takeaways

Patient-specific surgical instruments (PSIs) are single-use instruments customized to an individual patient's anatomy. They mark a significant advancement in approach to personalized treatment in Orthopedics. 

3D imaging techniques like CTs, MRIs, or X-ray scans and 3D printing technology can create these customized guides that can fit each patient perfectly. Orthopedic surgeons use these instruments intraoperatively to accurately place incisions, position implants, or perform other surgical tasks according to a surgeon approved preoperative plan. 

Potential benefits of patient-specific surgical instruments

Patient-specific surgical instruments offer many potential benefits. PSIs can help with: 

  • Better adherence to the preoperative plan
  • Improved surgical accuracy by better implant positioning
  • More precise bone correction 
  • Reducing operating times
  • Decreased blood loss 
  • Reducing instruments required for surgery

Additionally, PSIs can potentially enable junior surgeons to train in advanced techniques and perform more complex procedures.

Orthopedic Applications

Knee replacement surgery

Patient-specific surgical instruments can solve key challenges in total knee arthroplasty (TKA). PSIs aid in achieving precise implant positioning, especially in complex cases. During surgery, these guides are used to determine the resection angles made to the femur and tibia.

For example, Enhatch recently assisted in the launch of a patient-specific surgical instrument to solve a unique challenge in total knee arthroplasty (TKA). This instrument achieves all five femoral resections using a single instrument.

Hip replacement surgery

Patient-specific surgical instruments can help with the ideal positioning of acetabular and femoral components in total hip arthroplasty. They can help with accurate:

  • Bone cutting and reaming
  • Implant fixation
  • Guidewire insertion
Tumor resection and Osteotomy

Patient-specific surgical instruments have emerged as valuable tools in orthopedic oncology. This is particularly true for tumor resection and osteotomy procedures. For example, tumor resection requires precise planning in challenging areas like the sacrum and pelvis. Here, patient-specific instruments offer significant advantages.

PSIs also facilitate more accurate osteotomies. They ensure the removal of tumors with negative margins while preserving healthy bone stock. This precision is crucial for achieving successful limb-sparing surgeries. In such surgeries, the goal is to preserve the affected limb while effectively treating the tumor.

Spine surgeries

Pedicle screw placement in spinal surgery is a great use case for patient-specific surgical instruments. While image-guided and robotic systems can improve accuracy, there is a risk of increased radiation exposure. Using patient-specific surgical instruments can help increase accuracy, reduce costs, and improve patient safety.

Ankle replacements

In total ankle replacement solutions, 3D-printed tibia and talar (ankle bone) resection instruments are examples of applications of patient-specific surgical instruments. They ensure that the implants are placed accurately per the surgeon approved preoperative plan.

Enhatch’s preoperative planning portal was used to launch and manage patient-specific ankle solutions.

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Manufacturing patient-specific surgical guides

Materials Used

PSIs are typically manufactured using sterilizable, biocompatible materials resistant to deformation. These materials offer a range of properties suitable for different types of patient-specific surgical instruments. The choice of material depends on factors such as 

  • The specific surgical application
  • Desired mechanical properties
  • Biocompatibility requirements
  • Cost considerations

Nylon PA12 (Polyamide) is an example of a durable thermoplastic with balanced mechanical properties and fine-feature surface resolution suitable for additive manufacture of precision surgical instruments. It is known for its excellent strength, heat resistance, and biocompatibility. 

Radel PPSU (Polyphenylsulfone) is an example of a high-performance thermoplastic suitable for making surgical guides.

Process Overview
Medical Imaging

The process begins with the acquisition of medical imaging data (such as CT scans, MRI scans or X-rays) of the patient's anatomy. 

3D Modeling

The medical imaging data is processed, and specialized software is used to create a 3D anatomic model of the patient's anatomy. This model accurately represents the specific structures relevant to the surgical procedure.

Virtual Surgical Planning (VSP) and Design

Surgeons and engineers then work together to design the patient-specific surgical instruments. These instruments are customized to precisely fit the patient's anatomy. 

Next, surgeons can evaluate different approaches through virtual surgical simulations. They can assess potential risks and optimize the surgical plan.

3D Printing (Additive Manufacturing)

Once designed, 3D printing is used to manufacture the surgical instruments.

Quality Control and Testing 

After manufacturing, the surgical instruments undergo rigorous quality control and testing. This is to ensure they meet the required standards of accuracy and functionality.

Packaging and Sterilization

Once the surgical instruments pass quality control, they are carefully packaged and sterilized. The surgical instruments can also be provided non-sterile, requiring sterilization to occur at the point-of-care through an autoclave cycle.


The finalized, sterilized surgical instruments are delivered to the surgical team prior to the scheduled procedure.

The importance of preoperative planning

Preoperative planning or Virtual Surgical Planning (VSP) is critical to create patient-specific surgical instruments. An effective preoperative planning software solution is essential as:

  • Cases need to be initiated and managed on the system with all relevant details
  • Medical imaging data needs to be uploaded and reviewed easily
  • Multiple stakeholders (surgeon, engineer, sales rep, etc) need to collaborate seamlessly
  • Relevant reports have  viewed and approved easily

Integrating Artificial Intelligence (AI) has also proved to be a game changer. AI platforms can rapidly create detailed 3D anatomical models from CTs, MRIs, and even X-rays. AI can significantly accelerate segmentation with semi-automatic detection of bony landmarks and implant placement.

For example, recently, Enharch announced the U.S. Food and Drug Administration's (FDA) 510(k) clearance of a patient-specific instrumentation system for total knee arthroplasty. This system is redefining total knee arthroplasty with its AI-driven approach. AI algorithms can convert patient X-rays or CT images into detailed 3D anatomical models. The models can then be used to create highly personalized surgical guides more efficiently.

With Enhatch’s preoperative planning portal, you can plan and manage all your patient-specific cases in one place.

An FDA-approved surgical planning solution for patient-specific solutions.
A cloud-based platform to use from any laptop or tablet—no downloads or lengthy installations required.
Executive dashboard to manage all patient-specific cases from one place, and much more.
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Patient-specific surgical instruments represent a significant advancement in personalized orthopedic treatment. These single-use instruments are tailored to individual patient anatomies. 

These guides can potentially improve surgical accuracy and streamline surgical procedures. Ongoing advancements in material science and preoperative planning solutions can further increase the impact of these personalized guides in the future.


Patient‐specific cutting guides for total knee arthroplasty, retrieved from the NIH website:  Visit Page

Patient-Specific Surgical Guide for Total Hip Arthroplasty, retrieved from the Pubmed website:  Visit Page

Current Concepts in the Resection of Bone Tumors Using a Patient-Specific Three-Dimensional Printed Cutting Guide, retrieved from the MDPI website:  Visit Page

Patient-specific 3D-printed surgical guides for pedicle screw insertion: comparison of different guide design approaches, retrieved from the future medicine website:  Visit Page