Patient-specific instrumentation (PSI) is an advanced manufacturing technology that combines preoperative imaging, virtual surgical planning, and 3D printing to create custom surgical guides, jigs, and templates that fit precisely to an individual patient's anatomy. The workflow includes high-resolution preoperative imaging (CT scan with specific protocols for measurement accuracy), virtual surgical planning by surgeon or technician using specialized software (creating optimal implant position, cut planes, and trajectories), guide design and manufacturing (typically by additive manufacturing/3D printing of medical-grade biocompatible materials), and intraoperative use of these patient-matched guides for cuts, drill trajectories, or implant positioning.
Applications in orthopedics include: total knee arthroplasty (custom femoral and tibial cutting guides for distal femoral, anteroposterior femoral, proximal tibial cuts, and rotational reference) — most studied PSI application with mixed clinical results; total hip arthroplasty (less common, primarily for revision and complex deformity); complex fracture reconstruction (custom plate guides for malunion, deformity correction); periacetabular osteotomy and other corrective osteotomies; bone tumor resection (cutting guides ensuring oncologic margins while preserving function); spine surgery (pedicle screw trajectory guides, especially in deformity); shoulder arthroplasty (custom glenoid guides, particularly for severe deformity).
Advantages claimed for PSI include patient-specific anatomical fit, improved alignment accuracy (debated in TKA studies — meta-analyses show similar or marginal improvement compared to standard instrumentation), shorter surgical time (5-10 minutes savings), reduced number of instrument trays (sterilization cost savings), and possibly reduced blood loss in some studies; in complex cases (severe deformity, revision, oncologic), PSI provides definite advantages in addressing unique anatomic challenges. Disadvantages include higher cost (~$700-2000 per primary TKA case), 2-4 week lead time for design and manufacturing (may delay surgery), CT radiation exposure for planning, dependence on imaging accuracy and software/manufacturing precision, and inability to address intraoperative findings deviating from preoperative plan. Cost-effectiveness in primary TKA is debated; clinical benefit is clearer in complex deformity, revision, and tumor surgery.