Mintzer C M, Robertson D D, Rackemann S, Ewald F C, Scott R D, Spector M
Orthopedic Research Laboratory, Brigham and Women's Hospital, Boston, MA 02115.
Clin Orthop Relat Res. 1990 Nov(260):135-43.
Bone loss in the distal anterior femur in asymptomatic total knee arthroplasty (TKA) patients has been noted roentgenographically and during revision surgery. A retrospective roentgenographic review of 147 TKA cases was carried out to document bone loss. The influence that the mode of fixation (porous coated and cemented) and the implant design have on bone loss was examined. The time of onset and the progression of bone loss were studied. Bone loss occurred in the distal anterior femur in the majority of cases reviewed (68%). The prevalence of bone loss was independent of the mode of fixation and the implant design. By qualitative observation, roentgenographically detectable bone loss occurred within the first postoperative year and did not progress further. Previously three-dimensional finite element analysis demonstrated that the replacement of the bearing surface of the femur with a stiff metallic implant reduces the stress in the distal anterior femur by at least one order of magnitude. It is therefore speculated that the observed bone loss results from stress shielding. The apparent lack of progression may reflect the development of a new remodeling equilibrium under the altered stress conditions. The bone loss in the distal anterior femur described has not been implicated as a source of failure. However, since the bone strength in the femoral region is compromised as it becomes osteopenic, bone failure may occur with longer periods of cyclic loading. Furthermore, as a result of bone loss, revision arthroplasty may be more difficult.
在无症状的全膝关节置换术（TKA）患者中，通过X线检查和翻修手术已发现股骨远端前部存在骨质流失。对147例TKA病例进行了回顾性X线检查，以记录骨质流失情况。研究了固定方式（多孔涂层和骨水泥固定）和植入物设计对骨质流失的影响。对骨质流失的起始时间和进展情况进行了研究。在所审查的大多数病例（68%）中，股骨远端前部出现了骨质流失。骨质流失的发生率与固定方式和植入物设计无关。通过定性观察，X线可检测到的骨质流失发生在术后第一年，且未进一步进展。此前的三维有限元分析表明，用刚性金属植入物替换股骨的承重表面可使股骨远端前部的应力降低至少一个数量级。因此推测，观察到的骨质流失是应力遮挡所致。明显缺乏进展可能反映了在改变的应力条件下新的重塑平衡的发展。所述股骨远端前部的骨质流失尚未被认为是失败的原因。然而，由于股骨区域的骨强度在骨质减少时会受到损害，长期的周期性负荷可能会导致骨衰竭。此外，由于骨质流失，翻修关节成形术可能会更加困难。
