Poss R
Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
Clin Orthop Relat Res. 1992 Jan(274):194-201.
The human skeleton loses bone mass with increasing age. A wide variety of evidence suggests that the skeleton compensates for this decreased bone mass by increasing the second moment of area in the midshaft of long bones. Strain is the mechanical transducer of bone's adaptation to its mechanical environment. In the absence of strain, bone resorption occurs. Contemporary femoral prostheses are stiffer than the cortical bone that serves as their host and, therefore, induce stress shielding and bone resorption that augments the naturally occurring loss of bone mass with age. With the expectation that total hip replacement can endure 15-25 years, one must be aware that a new limit to its longevity may be the biologic failure of the host bone. Particulate debris, stress shielding, and the natural consequences of aging are conspiring to make the proximal femur a diminishing site. The design strategy and materials of fabrication of future total hip prostheses should seek to maximize the preservation of bone.
人类骨骼会随着年龄增长而流失骨量。大量证据表明，骨骼通过增加长骨中轴的截面二次矩来补偿这种骨量减少。应变是骨骼适应其力学环境的力学传感器。在没有应变的情况下，会发生骨吸收。现代股骨假体比作为其宿主的皮质骨更硬，因此会导致应力遮挡和骨吸收，这加剧了随着年龄增长自然发生的骨量流失。鉴于全髋关节置换预期能使用15至25年，必须意识到其使用寿命的一个新限制可能是宿主骨的生物学失效。颗粒碎片、应力遮挡以及衰老的自然结果共同作用，使得股骨近端成为一个骨量不断减少的部位。未来全髋关节假体的设计策略和制造材料应致力于最大限度地保留骨量。
