Patient-Specific Implants in Orthopaedics
DNB Orthopaedics • May 2024 • Paper IV • 10 Marks
Introduction
Conventional orthopaedic implants are manufactured in a limited range of standard sizes and shapes. Although modularity permits adaptation to most patients, there are situations in which abnormal anatomy, severe bone loss, deformity, previous surgery or tumour resection cannot be adequately reconstructed using an off-the-shelf implant.
Advances in CT-based three-dimensional modelling, computer-aided design (CAD), computer-aided manufacturing (CAM), additive manufacturing and 3D printing have made it possible to manufacture implants specifically for the anatomy and reconstructive requirements of an individual patient.
Patient-specific implant (PSI) = an implant designed and manufactured for the anatomy and surgical requirements of a particular patient using patient-specific imaging data.
Important Terminology
| Term | Meaning |
|---|---|
| Patient-specific implant | Implant individually designed to fit or reconstruct the anatomy of one particular patient. |
| Patient-specific instrument | Custom cutting, drilling, resection or positioning guide used during surgery; it is not necessarily implanted. |
| 3D-printed anatomical model | Physical replica of the patient's anatomy used for planning, simulation or implant contouring. |
| Additive manufacturing | Layer-by-layer fabrication of an object from a digital 3D model. |
Exam pearl: Do not use “patient-specific implant”, “patient-specific instrumentation” and “3D-printed model” interchangeably. They are related technologies but…