Lehmann Wolfgang, Rupprecht Martin, Hellmers Nils, Sellenschloh Kai, Briem Daniel, Püschel Klaus, Amling Michael, Morlock Michael, Rueger Johannes Maria
Department of Trauma, Hand, and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg 20246, Germany.
J Trauma. 2010 Jun;68(6):1459-63. doi: 10.1097/TA.0b013e3181bb8d89.
Because of an increasing life expectancy of patients and the rising number of joint replacements, peri- and interprosthetic femoral fractures are a common occurrence in most trauma centers. This study was designed to answer two primary questions. First, whether the fracture risk increases with two intramedullary implants in one femur; and second, whether a compression plate osteosynthesis is sufficient for stabilizing an interprosthetic fracture.
Twenty-four human cadaveric femurs were harvested and four groups were matched based on the basis of bone density using a peripher quantitative computer tomography (pQCT). All groups-(I) hip prosthesis with a cemented femoral stem; (II) hip prosthesis and retrograde femoral nail; (III) hip prosthesis, retrograde femoral nail, and lateral compression plate; (IV) all three implants with an additional simulated interprosthetic fracture-were biomechanically tested in a four-point bending in lateral-medial direction.
The second group with two intramedullary implants exhibited 20% lower fracture strength in comparison with group 1 with proximal femoral stem only. The stabilization of an interprosthetic fracture with a lateral compression plate (group IV) resulted in a fracture strength similar to femur with prosthesis only.
Two intramedullary implants reduce the fracture strength significantly. If an interprosthetic fracture occurs, sufficient stability can be achieved by a lateral compression plate. Because two intramedullary implants in the femur may decrease the fracture strength, the treatment of supracondylar femoral fractures with a retrograde nail in cases with preexisting ipsilateral hip prosthesis should be reconsidered.
由于患者预期寿命的增加以及关节置换数量的上升，股骨假体周围和假体间骨折在大多数创伤中心都很常见。本研究旨在回答两个主要问题。第一，一根股骨内植入两枚髓内固定装置是否会增加骨折风险；第二，加压钢板接骨术是否足以稳定假体间骨折。
采集24具人尸体的股骨，并使用外周定量计算机断层扫描（pQCT）根据骨密度将其分为四组进行匹配。所有组——（I）带骨水泥型股骨柄的髋关节假体；（II）髋关节假体和逆行股骨钉；（III）髋关节假体、逆行股骨钉和外侧加压钢板；（IV）所有三种植入物外加模拟的假体间骨折——均在内外侧方向的四点弯曲试验中进行生物力学测试。
与仅植入近端股骨柄假体的第一组相比，植入两枚髓内固定装置的第二组骨折强度降低了20%。使用外侧加压钢板稳定假体间骨折（第四组）后的骨折强度与仅植入假体的股骨相似。
两枚髓内固定装置会显著降低骨折强度。如果发生假体间骨折，外侧加压钢板可实现足够的稳定性。由于股骨内植入两枚髓内固定装置可能会降低骨折强度，对于同侧已有髋关节假体的病例，使用逆行髓内钉治疗股骨髁上骨折应重新考虑。
