Perren S M, Fernandez Dell'Oca A, Lenz M, Windolf M
Institute for Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, Queensland, 4059, Australia.
Acta Chir Orthop Traumatol Cech. 2011;78(3):190-9.
Periprosthetic fractures are increasingly frequent. The fracture may be located over the shaft of the prosthesis, at its tip or below. The treatment of explosion fractures is difficult because the shaft blocks the application of implants, like screws, which need to penetrate the medullary cavity. The cerclage, as a simple periosteal loop, made of wire or more recently cable, does not only avoid the medullary cavity. Its centripetal mode of action is well suited for reducing and maintaining radially displaced fractures. Furthermore, the cerclage lends itself well for minimally invasive internal fixation. New insight challenges the disrepute of which the cerclage technology suffered for decades. The outcome of cerclage fixation benefits from an improved understanding of its technology, mechano-biology and periosteal blood supply. Preconceived and generally accepted opinions like "strangulation of blood supply" need to be re-examined. Recent mechanical evaluations demonstrate that the wire application may be improved but cable is superior in hand- ling, maintenance of tension and strength. Beside the classical concepts of absolute and relative stability a defined stability condition needs consideration. It is typical for cerclage. Called "loose-lock stability" it specifies the situation where a loosened implant allows first unimpeded displacement changing abruptly into a locked fixation preventing further dislocation.
假体周围骨折越来越常见。骨折可能位于假体柄部、尖端或其下方。爆裂性骨折的治疗很困难，因为假体柄会阻碍诸如螺钉等需要穿透髓腔的植入物的应用。环扎术，作为一种简单的骨膜环，由钢丝或最近的缆线制成，不仅避开了髓腔。其向心作用方式非常适合于复位和维持径向移位的骨折。此外，环扎术非常适合微创内固定。新的见解对环扎技术几十年来所遭受的恶名提出了挑战。环扎固定的效果得益于对其技术、机械生物学和骨膜血供的更好理解。诸如“血供绞窄”等先入为主且被普遍接受的观点需要重新审视。最近的力学评估表明，钢丝的应用可能会有所改进，但缆线在操作、张力维持和强度方面更具优势。除了绝对稳定性和相对稳定性的经典概念外，还需要考虑一种特定的稳定性条件。这是环扎术的典型特征。称为“松锁稳定性”，它指的是植入物松动时首先允许无阻碍移位，然后突然转变为锁定固定以防止进一步脱位的情况。
