Objectives:Three dimensional (3D) printing technology has many current and future applications in orthopaedics. The objectives of this article are to review published literature regarding applications of 3D technology in orthopaedic surgery with a focus on knee surgery.Methods:A narrative review of the applications of 3D printing technology in orthopaedic practice was achieved by a search of computerised databases, internet and reviewing references of identified publications.Results:There is current widespread use of 3D printing technology in orthopaedics. 3D technology can be used in education, preoperative planning and custom manufacturing. Custom manufacturing applications include surgical guides, prosthetics and implants. Many future applications exist including biological applications. 3D printed models of anatomy have assisted in the education of patients, students, trainees and surgeons. 3D printed models also assist with surgical planning of complex injuries or unusual anatomy. 3D printed surgical guides may simplify surgery, make surgery precise and reduce operative time. Computer models based on MRI or CT scans are utilised to plan surgery and placement of implants. Complex osteotomies can be performed using 3D printed surgical guides. This can be particularly useful around the knee. A 3D printed guide allows pre osteotomy drill holes for the plate fixation and provides an osteotomy guide to allow precise osteotomy. 3D printed surgical guides for knee replacement are widely available. 3D printing has allowed the emergence of custom implants. Custom implants that are patient specific have been particularly used for complex revision arthroplasty or for very difficult cases with altered anatomy. Future applications are likely to include biological 3D printing of cartilage and bone scaffolds.Conclusion:3D printing in orthopaedic surgery has and will continue to change orthopaedic practice. Its role is to provide safe, reproducible, reliable models with reduced operative time and improves patient outcomes compared to traditional surgical techniques. Long term follow up of the techniques is still required.