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Correction of leg length discrepancy and measuring length of neck resection; the height ofthe femoral stem was adjusted to correct any leg length discrepancy by placing the center of thehead above the center of the cup by the same length of discrepancy. Then the level of the neckresection was marked at the level of the stem collar and the femoral neck cut was measured bya digital ruler from the tip of the lesser trochanter to the mark of neck resection. In case of leglength discrepancy, the height of the femoral neck cut was adjusted accordingly to compensatefor the leg length discrepancy. For example, if the affected leg is 20 mm short, place the centreof the head 20 mm above the centre of the cup.Intraoperatively, the surgeon performed the femoral neck osteotomy at the level determined bypreoperative templating. Postoperatively, the leg length was measured and compared to thepreoperative leg length. Preoperatively, the leg length discrepancy ranged from 5 to 30 mm. Inall cases, the leg was short on the side of THR (ipsilateral). Leg length discrepancy was adjustedin all THR cases. Postoperatively, the accuracy of the correction was found to be within 5millimeters i.e. less than 5mm of shortening or lengthening). Intraoperatively, the level offemoral neck cut ranged from 1 to 44 mm.Digital templating is useful in adjusting leg length discrepancy. In addition, there were otherbenefits such as predication of femoral and acetabular implant sizes, restoration of normal hipcentre, and optimization of femoral offset.Thursday, October 7, 2010, 13:30-14:10Session B5: Computer Navigation in TKR 1Correction of Complex Femoral or Tibial Shaft Deformities During TotalKnee Arthroplasty Using Computer Assisted Techniques*Mahmoud Hafez - October 6th - Cairo, Egypt*Email: mhafez@msn.comIntroductionThere is a controversy with regard to the treatment of osteoarthritis (OA) of the knee in patientswith considerable deformities of the femoral or tibial shafts. Some surgeons prefer to correct thedeformity while performing TKA at the level of the knee joint. However, this techniquerequires accurate planning and execution of the planned cuts. In addition, the use ofintramedullary guides in such cases may not be possible or desirable and may lead tocomplications. There is a strong indication for using navigation in such cases.MethodsThe navigation technique was used in both laboratory and clinical setting, First, we comparedbetween navigational and conventional techniques in performing TKA in 24 plastic kneespecimens (Sawbones, Sweden) that have osteoarthritic changes and complex tibial or femoraldeformities. A demo kit for conventional instrumentation of posterior stabilised TKA (Scorpio,Stryker) was used for 12 cases and an image-free navigation system (Stryker) was used for acorresponding 12 cases. There were 4 different deformities; severe mid-shaft tibial varus, severedistal third femoral valgus, complex deformity distal femur and deformity following a revisionTKA. The surgical procedures were performed by 3 arthroplasty surgeons, each surgeonoperated on 8 knee specimens (4 knees in each arm of the study with 4 different deformities).file:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]