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Poster: 31Clinical and Laboratory Validation of a Novel Technique of Patient SpecificTemplating (Cutting Guides) for Total Knee ReplacementAbstract*Mahmoud Hafez - October 6th - Cairo, Egypt*Email: mhafez@msn.comA new technique using computer assisted preoperative planning to produce patient specifictemplates for total knee arthroplasty was previously reported. This technique replacedconventional instrumentation including medullary guides and has significantly reducedoperative time and the need for surgical assistants in TKA. The femoral and tibial templates actas cutting blocks that match the surface geometry of the distal femur and proximal tibial.However, errors in bone cutting and alignment may occur as a result of incorrect positioning ofthese templates. The purpose of this study was to test the accuracy and reliability of positioningthe femoral and tibial templates by 5 observers. Each observer performed the experiment 5times using femoral and tibial templates that were produced for a plastic knee model based onCT scan data. A navigation system measured alignment and bone cutting level for all referencecuts (tibial, posterior femoral and distal femoral). The mean alignment error was 0.67º(maximum 2.5º). The mean error for bone cutting was 0.32 mm (maximum 1 mm). Thepositioning of the templates was reliable, as there was no significant intraobserver andinterobserver variation. This study showed a satisfactory level of accuracy and reliability of thistechnique. It appears that patient specific templating technique has several advantages overconventional instrumentation and is a simple and practical alternative to navigation and robotictechniques for TKA.Key words: Reliability, accuracy, computer-assisted TKA, patient-specific, templates, rapidprototyping, surface matchingINTRODUCTIONThe current techniques for total knee arthroplasty (TKA) rely on conventional instrumentationthat consists of numerous pieces of jigs and fixtures. These are cumbersome, as they require setup, assembly, dismantling and cleaning, which are time consuming. Alignment guides perforatemedullary canals, leading to a higher risk of bleeding 3 , infection 25 , fat embolism 18 , andfractures. 5 Reusable instruments carry a theoretical risk of contamination and may overloadhospital sterilization services.file:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]