TRIGEN INTERTAN vs Stryker Gamma3 summary

Transcription

1 TRIGEN INTERTAN vs Stryker Gamma3 summary Initial stiffness of INTERTAN construct almost 4% greater than Gamma3 INTERTAN femoral head rotation and varus collapse initially up to 84% lower than Gamma3 After 14, cycles, interfragmentary movement on average 33% less on INTERTAN when compared to Gamma3 Implant toggle/medial translation in proximal femur significantly lower in INTERTAN vs Gamma3 providing higher survival rate Average failure load was over 2N higher on INTERTAN than Gamma3

2 Intro Problems in hip fractures Insufficient stabilization Micromotion Shear forces at fracture site Delayed healing/failure Complication rates in proximal femur fractures as high as 16% in highly unstable fractures Malalignment and malrotation of femur Delayed healing causing implant failure Micromotion caused by Collapse of proximal fragment Movement between fracture fragments Lack of interfragmentary compression Instability of device medial translation of the construct due to nail toggle in proximal femur Conclusions Trapezoidal shape Integrated screws Integrated screws Reduced varus collapse of femoral head Reduced rotation of femoral head and neck Reduced movement between fracture fragments Interfragmentary compression in a linear fashion Trapezoidal shape Reduced toggling of the nail in the proximal femur Enhanced nail stability helping to prevent medial translation and implant failure

3 Mechanical testing 1 angle adduction/1 angle extension out-of-plane configuration used to simulate the resulting hip force at heel strike during gait Cyclical fatigue testing performed under increasing axial load until failure Each Femora specimen cut using proximal femoral osteotomies to replicate AO/OTA Type 31A2.2 unstable pertrochanteric fracture Results Mean value of the failure load for the TRIGEN INTERTAN device was 164 ± 56N compared to 143 ± 6N for Gamma3 In 9 out of 1 comparisons, the TRIGEN INTERTAN device survived on average 51, ± 4, additional cycles more than Gamma3

4 Results: Femoral head rotation Absolute value of rotation of the femoral head around the axis of the lag screw measured every 2, cycles 7 6 INTERTAN Gamma3 5 Rotation [degrees] , 4, 6, 8, 1, 12, 14, Cycles Highlights Rotation of femoral head higher for Gamma3 (1.7 ± 1.5º angle) compared to the TRIGEN INTERTAN device (.3 ±.3º angle) for up to 12, cycles Less femoral head rotation around the lag screw may result in less chance for leg length discrepancy due to femoral neck shortening and potentially better healing rates

5 Results: Varus collapse Varus collapse of the femoral head in the frontal plane, measured every 2, cycles. -.5 INTERTAN Gamma3-1. Varus collapse [degrees] , 4, 6, 8, 1, 12, 14, Cycles Highlights Baseline varus collapse of the femoral head was higher for Gamma3 (1.1 ±.5º) compared to the TRIGEN INTERTAN device (.3 ±.2º angle) for up to 12, cycles Less varus collapse may result in a more normal gait for the patient making it easier to ambulate and return to pre-fracture status quicker

6 Results: Implant stiffness Stiffness of the bone implant construct measured every 2, cycles INTERTAN Gamma3 1 Stiffness [N/mm] , 4, 6, 8, 1, 12, 14, Cycles Highlights Initial stiffness of the TRIGEN INTERTAN device was 38% higher compared to Gamma3 for up to 12, cycles Stiffer construct may result in quicker healing and return to pre-fracture status quicker

7 Results: Cycles to failure/survivability Rate of survival for the single lag screw (Gamma3 ) and the interlocking lag screw (INTERTAN ) constructs in relation to number of cycles (n = 1 per group). 25, INTERTAN Gamma3 2, 15, 1, 5, Cycles Survivability Highlights The first failure in the Gamma3 group failed at 142,248 cycles compared to the first failure in the INTERTAN group failed at 191,885 cycles Survivability of Gamma3 construct (193, ± 35, cycles) was significantly reduced relative to INTERTAN construct (235, ± 38, cycles) Stronger nail in fatigue means it can withstand a potentially higher load for a longer period of time allowing a longer time for the bone to heal

8 Reference Hoffmann S, Paetzold R, Stephan D, Püschel K, Buehren V, Augat P. Biomechanical evaluation of interlocking lag screw design in intramedullary nailing of unstable pertrochanteric fractures. J Orthop Trauma. 213 Sep;27(9): Smith & Nephew, Inc Goodlett Farms Parkway Cordova, TN 3816 USA Telephone: Information: Orders and Inquiries: Trademark of Smith & Nephew. Certain marks Reg. US Pat. & TM Off. All Trademarks acknowledged. 213 Smith & Nephew, Inc. All rights reserved. 938 v1 11/13