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Results:We report cases of hip replacements performed using the subscribed navigation system inpatients with preoperative leg length discrepancy and abnormal hip morphology to emphasizethe value of navigation in such cases.Conclusion:The subscribed navigation system allows accurate positioning of the components during totalhip arthroplasty and enables the surgeon to control leg lengthening, offset and stability.Therefore, improved long term outcome can be expected. Longer clinical follow-up is requiredto confirm this assumption.Friday, October 8, 2010, 14:50-15:10Session B13: Imaging TechnologyAdjusting Leg Length Discrepancy in Hip Arthroplasty Using DigitalTemplating System*Mahmoud Hafez - October 6th - Cairo, Egypt*Email: mhafez@msn.comDigital templating was used in 50 patients who underwent THA using Merge Ortho software,Cedara. Clinical examination was performed first, to measure leg lengths and account for pelvicobliquity and flexion deformity. Good quality digital radiographs were obtained withanteroposterior and lateral views extending beyond the tip of the femoral component and thecement restrictor. A coin was placed on the ASIS to help in determining radiologicalmagnificationDigital radiographs were saved in DICOM format and imported to EndoMap software system.A 6-step technique was used for templating as follows:1. Radiographic assessment; looking at the quality of bone, amount of bone stock,dysplasia, osteophytes, and other abnormalities2. Correction of magnification; following the specific instructions of the software, bymeasuring the diameter of the coin on the digital radiograph.3. 3. Measuring leg length discrepancy; the software system automatically calculatedthe leg length discrepancy, even in the presence of pelvic obliquity (Figure1).4. 4. Templating acetabular component; the desired cup was selected from the implantlibrary after identifying important landmarks. The size and position was modified to fitthe acetabulum and to restore the center of rotation of the hip, considering minimal boneremoval and sufficient bone coverage laterally.5. Templating femoral component; the size and position of the desired stem was adjustedto fit the femoral canal, different offsets were compared to find the best match for thepatient's original offset.file:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]