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Thursday, October 7, 2010, 14:20-15:00Session B6: Computer Navigation in TKR 2Comparing Femoral Component Rotation Using a Force Sensing DeviceVersus Conventional Methods With Anatomic LandmarksIntroduction*Stefan Kreuzer - Memorial Bone and Joint Research Foundation - Houston, USAKevin Leffers - Memorial Bone and Joint Research Foundation - Houston, USA*Email: skreuzer@mbjc.netTotal knee arthroplasty is traditionally performed using bone anatomy to dictate femoralimplant rotation and soft tissue release to balance any resulting deficiencies. A force sensingdevice has been developed that reverses this conventional order. It measures the forces in themedial and lateral compartments and dictates the femoral rotation cuts when these are equal.The purpose of this study was to compare the traditional methods of femoral rotation (TEA, APaxis, and posterior referenced) to this novel approach using computer navigation with the forcesensor to determine a balanced flexion gap.MethodsThis was a prospective cohort study of 50 consecutive primary TKA’s. Inclusion criteria werediagnosis of OA and primary TKA. Exclusion criteria were inability to use force sensingdevice. The cohort consisted of 29 females and 19 males with an average age of 70.8 years(50.2-90.3) and BMI of 32.0 (19.8 – 56.1). Intra-operative data was collected using computernavigation. Post operative CT scans were obtained on 31 of the 50 knees to assess femoralimplant rotation to the patients’ true TEA. CT measurements were made by two differentobservers. Simple descriptive statistics and t-tests were used for analysis.ResultsThe novel approach, which is assumed to be a well-balanced/symmetric flexion gap, had anaverage rotation within 1.8 degrees to the TEA as evidenced by the CT measurements. Thenavigation data showed that the posterior referenced, TEA, and AP method would have resultedin an asymmetric flexion gap (greater than 3° from CT observed TEA) in 52%, 52%, and 44%respectively as opposed to the novel approach at 23%.ConclusionThis study showed that this novel device when accompanied with computer navigation canresult in a balanced flexion gap and femoral implant rotation within 3° of the TEA 77% of thetime.Saturday, October 9, 2010, 16:00-16:50Session A23: Knee Mechanicsfile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]