Goodman S, Toksvig-Larsen S, Aspenberg P
Department of Orthopaedic Surgery, University Hospital, Lund, Sweden.
J Biomed Mater Res. 1993 Feb;27(2):247-53. doi: 10.1002/jbm.820270215.
The micromotion chamber consists of a titanium outer cylinder and a central core, which are pierced by a transverse 1-mm canal for tissue ingrowth. Six weeks after implantation in the proximal tibia in mature rabbits, the outer cylinder is osseointegrated; the central core can then be moved in relation to the fixed outer cylinder. Thus, the tissue growing through the pore, from the cylinder into the core, can be subjected to motion of a predetermined amplitude and frequency. In this study we investigate the influence of pore cross-sectional shape on tissue ingrowth in the canal. In six animals, the outer cylinder was pierced by a square 1-mm hole that was congruent with the square hole in the core; in five animals, the hole in the cylinder was round. The cross-sectional area of the square hole in the cylinder was about 21% greater than in a round hole. In all cases, the channel in the inner core was 1 x 1 x 5-mm quadrate. All chambers underwent 20 cycles/day of micromotion for a 3-week period. The amplitude of the micromotion was 0.5 mm. Chambers containing cylinders with a round hole demonstrated less bone ingrowth as compared to cylinders with a square hole. This observation may be due to several factors including the greater cross-sectional area of the square versus the round hole in the cylinder and the enhanced congruity provided by the square outer and inner holes, versus a round outer and square inner hole.
微动腔由一个钛制外圆柱体和一个中心芯组成，它们被一个用于组织向内生长的1毫米横向通道贯穿。在成年兔胫骨近端植入六周后，外圆柱体实现骨整合；然后中心芯可以相对于固定的外圆柱体移动。因此，通过孔隙从圆柱体生长到芯中的组织可以受到预定振幅和频率的运动。在本研究中，我们调查了孔隙横截面形状对通道内组织向内生长的影响。在六只动物中，外圆柱体被一个与芯中的方孔全等的1毫米方孔贯穿；在五只动物中，圆柱体上的孔是圆形的。圆柱体中方孔的横截面积比圆孔大约21%。在所有情况下，内芯中的通道都是1×1×5毫米的方形。所有的腔在3周时间内每天进行20次微动循环。微动的振幅为0.5毫米。与带有方孔的圆柱体相比，带有圆孔的圆柱体的骨向内生长较少。这一观察结果可能归因于几个因素，包括圆柱体中方孔相对于圆孔更大的横截面积，以及方孔的外孔和内孔比圆孔的外孔和方孔内孔提供的更高的一致性。
