Braun Benjamin M, Ross Jeremy A, Swart Eric F
Orthopedics. 2023 Jan-Feb;46(1):35-38. doi: 10.3928/01477447-20221003-03. Epub 2022 Oct 6.
Distal femur fractures above a total knee arthroplasty (TKA) are challenging. These fractures can be fixed with a retrograde intramedullary nail (rIMN), but the design of the femoral component of the TKA influences the starting point for an rIMN. We performed a biomechanical study to evaluate how different TKA components influence the starting point for an rIMN and how that can lead to a deformity in the sagittal plane. We simulated a distal femur fracture with three different arthroplasty components. We used three different implants to simulate fracture reduction and measured the resultant sagittal plane deformity. Low and moderate femoral component ratio (FCR) design components were able to maintain fracture alignment within 5° of anatomic. High FCR component (more posterior starting point) sagittal plane deformities of up to 15° were observed with both the straight and medium Herzog bend nails, which was statistically significant (<.001). Use of a high Herzog bend nail decreased the deformity by an average of 6°, which was statistically significant (<.001). There is variability in how the TKA design affects the starting point and thus the sagittal plane alignment after fixation. This study helps quantify the effect of arthroplasty component design on fracture alignment. [. 2023;46(1):35-38.].
全膝关节置换术（TKA）以上的股骨远端骨折具有挑战性。这些骨折可用逆行髓内钉（rIMN）固定，但TKA股骨组件的设计会影响rIMN的起始点。我们进行了一项生物力学研究，以评估不同的TKA组件如何影响rIMN的起始点，以及这如何导致矢状面畸形。我们用三种不同的关节置换组件模拟股骨远端骨折。我们使用三种不同的植入物模拟骨折复位并测量由此产生的矢状面畸形。低和中等股骨组件比率（FCR）设计组件能够将骨折对线维持在解剖学角度5°以内。使用直型和中等赫尔佐格弯钉时，高FCR组件（起始点更靠后）的矢状面畸形高达15°，具有统计学意义（<.001）。使用高赫尔佐格弯钉可使畸形平均减少6°，具有统计学意义（<.001）。TKA设计对起始点以及固定后矢状面对线的影响存在差异。本研究有助于量化关节置换组件设计对骨折对线的影响。[. 2023;46(1):35 - 38.]
