3D workflow for Osteotomies

In my role as a biomedical engineer, I’ve had the opportunity to work closely with orthopedic surgeons on more than 350 corrective osteotomy cases. These cases have given me deep insight into how technology can enhance surgical precision and patient outcomes, especially through custom surgical guide design and 3D planning.

Here’s a look into how these surgeries were planned and executed using advanced biomedical tools.

Step 1: Receiving the CT Scan Data

Every case begins with CT imaging. DICOM files are provided by the hospital, which gives the raw anatomical data we need to begin.

Step 2: Segmentation

Using software like Mimics, 2D scan slices are converted into a detailed 3D model of the patient's bones. This segmentation process helps isolate the anatomy and allows the doctors to see the exact extent and angle of the deformity (Including the rotational aspect of the deformity).

Step 3: Planning the Surgery Virtually

• The segmented bones are aligned to a standing X-ray (Scanogram) to simulate a weight-bearing CT view. This alignment allows for more accurate biomechanical evaluation.

• Biomechanical angles are assessed, and the required correction is calculated.

• Osteotomy cuts are simulated on the 3D model, and the correction is digitally performed.

• Hardware components, including plates, screws, and implants, are virtually positioned on the corrected model.

• The plan is reviewed and finalized in collaboration with the operating surgeon.

This step is critical. It ensures that every angle and movement is pre-decided, helping the surgeon work with clarity in the OR.

Step 4: Designing the Custom Surgical Guide

Once the plan has been approved, a patient-specific surgical guide is designed. The correction process is reverse engineered by tracing back from the final outcome to determine the screw and implant positions in the pre-corrected state. Based on this, a guide is developed to fit precisely on the patient’s bone. The guide includes:

• Cutting slots for the osteotomy

• Drill holes for screw fixation

• Reference surfaces for proper anatomical alignment

Step 5: 3D Printing the Guide

After the design is finalized, the guide is exported as an STL file and prepared for additive manufacturing. Quality control and compliance with ISO 13485:2016 are maintained throughout.

Once printed, the guide is sterilized and dispatched to the hospital, ready for use during surgery.

Step 6: Surgery Day

With the pre-designed guide in hand, surgeons can perform highly precise bone cuts without needing to calculate angles mid-surgery. The guide simplifies the process, minimizes surgical time, reduces fluoroscopy exposure, and boosts confidence - all while improving patient outcomes.

These cases taught me how crucial collaboration, precision, and planning are in the world of medical innovation. Every case might be unique, but the goal remains the same: to make surgeries safer, faster, and more accurate.