Convened under the auspicious of esteemed endorsers - ISTA

Friday, October 8, 2010, 16:30-17:20Session A16: Computer Navigation in THAComplex Acetabular Revision Using Computer-Aided Planning for Patient-Specific Implant and Guide.*Hendrik Delport - AZ Nikolaas - Sint Niklaas, BelgiumMichiel Mulier - Univeristy of Leuven - Leuven, BelgiumFrederik Gelaude - Mobelife - Leuven, BelgiumTim Clijmans - Mobelife - Leuven, Belgium*Email: hendrik.delport@telenet.beThe number of joint revision surgeries is rising, and the complexity of the cases is increasing. In58% of the revision cases, the acetabular component has to be revised. For these indications,literature decision schemes [Paprosky 2005] point at custom pre-shaped implants. Any standarddevice would prove either unfeasible during surgery or inadequate in the short term. Studiesshow that custom-made triflanged implants can be a durable solution with good clinical results.However, the number of cases reported is few confirming that the device is not in widespreaduse.Case ReportA patient, female 50 yrs old, diagnosed having a pseudotumor after Resurfacing Arthroplastyfor osteo-arthritis of the left hip joint. The revision also failed after 1 y and she developed apelvic discontinuity . X-ray and Ct scans were taken and sent to a specialized implantmanufacturer [Mobelife, Leuven, Belgium]. The novel process of patient-specific implantdesign comprises three highly automated steps.In the first step, advanced 3D image processing presented the bony structures and implantcomponents. Analysis showed that anterior column was missing, while the posterior column wasdegraded and fractured. The acetabular defect was diagnosed being Paprosky 3B. The formeracetabular component migrated in posterolateral direction resulting in luxation of the joint. Thereconstruction proposal showed the missing bone stock and anatomical joint location.In the second step, a triflanged custom acetabular metal backing implant was proposed. Thebone defect (35ml) is filled with a patient-specific porous structure which is rigidly connectedto a solid patient-specific plate. The proposed implant shape is determined taking into accountsurgical window and surrounding soft tissues. Cup orientation is anatomically analyzed forinclination and anteversion. A cemented liner fixation was preferred (Biomet Advantage48mm). Screw positions and lengths are pre-operatively planned depending on bone quality,and transferred into surgery using jig guiding technology (Materialise NV, Leuven, Belgium) .In the third step, the implant design was evaluated in a fully patient-specific manner indedicated engineering (FEA) software. Using the novel automated CT-based methodology,patient-specific bone quality and thickness, as well as individualised muscle attachments andmuscle and joint forces were included in the evaluation.Implants and jig were produced with Additive Manufacturing techniques under ISO 13485certification, using respectively Selective Laser Melting (SLM) techniques [Kruth 2005] inmedical grade Ti6Al4V material, and the Selective Laser Sintering technique using medicalgrade epoxy monomer. The parts were cleaned ultrasonically, and quality control wasperformed by optical scanning [Atos2 scanning device, GOM Intl. AG, Wilden, Switzerland].Sterilization is performed in the hospital.CONCLUSIONA unique combination of advanced 3D planning, patient-specific designed and evaluatedimplants and drill guides is presented. This paper illustrates, by means of a clinical case, thefile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]