Sugiyama H, Whiteside L A, Engh C A, Otani T
Biomechanical Research Laboratory, St Louis, MO 63141.
Orthopedics. 1994 Jul;17(7):583-8. doi: 10.3928/0147-7447-19940701-06.
Micromotion of a bone-ingrown anatomic medullary locking (AML) femoral component was evaluated in a specimen retrieved from a 66-year-old man who died 4 years following total hip replacement. Radiographic signs suggested bone ingrowth into the proximal porous coating, but a radiolucent line surrounded by a sclerotic line was present around the distal stem. Both torsional and axial loading to physiologic levels elicited minimal micromotion at the proximal bone-prosthesis interfaces. However, medial-lateral micromotion at the distal tip was found to be as high as 44 microns with axial load. An AML femoral component of similar design was inserted into the opposite normal femur using the cementless press-fit technique originally used for the implanted specimen. Micromotion proximally was much greater in the freshly implanted systems in response to both torsional and axial loading than in the bone ingrown specimen. However, distal medial-lateral micromotion was much greater for the bone-ingrown stem. These findings show that bone ingrowth provides rigid fixation of the implant to bone; however, flexibility of the femur causes increased micromotion of the femur around the smooth distal stem despite initial tight distal fit.
对一例解剖型骨长入髓内锁定（AML）股骨假体的微动情况进行了评估，该假体取自一名66岁男性，其在全髋关节置换术后4年死亡。影像学征象提示近端多孔涂层有骨长入，但远端柄周围存在一条被硬化线包绕的透亮线。对假体施加至生理水平的扭转和轴向负荷时，近端骨-假体界面处产生的微动极小。然而，轴向负荷作用下，远端尖端处的内外侧微动高达44微米。采用最初用于植入标本的非骨水泥压配技术，将一个设计类似的AML股骨假体植入对侧正常股骨。与骨长入标本相比，新植入系统在扭转和轴向负荷作用下近端的微动要大得多。然而，骨长入柄的远端内外侧微动要大得多。这些研究结果表明，骨长入可使植入物牢固地固定于骨；然而，尽管远端最初配合紧密，但股骨的柔韧性会导致股骨在光滑的远端柄周围产生更大的微动。
