Moroni A, Toksvig-Larsen S, Maltarello M C, Orienti L, Stea S, Giannini S
Department of Orthopaedic Surgery, Bologna University, Rizzoli Orthopaedic Institute, Italy.
J Bone Joint Surg Am. 1998 Apr;80(4):547-54. doi: 10.2106/00004623-199804000-00011.
Three types of surfaces for external fixation pins were compared. One hundred and eight stainless-steel tapered 5/6-millimeter pins were divided into three groups: thirty-six pins remained uncoated (Group A), thirty-six were plasma-sprayed with hydroxyapatite (Group B), and thirty-six were plasma-sprayed with titanium (Group C). The pins were implanted in the left tibia of eighteen sheep, with each sheep receiving six pins from the same group. A unilateral fixator then was assembled on the pins. The medial aspect of the mid-part of the tibial diaphysis was exposed, and a five-millimeter-long cylinder of bone was removed so that load would be borne by the bone-pin interfaces. Six weeks after the procedure, radiographs demonstrated rarefaction of twenty-nine pin tracks in Group A, fifteen in Group B, and thirty in Group C (p = 0.021 for Group A compared with Group B and p = 0.016 for Group B compared with Group C). The mean final insertion torque (and standard deviation) was 4360+/-1050 newton-millimeters in Group A, 3420+/-676 newton-millimeters in Group B, and 3740+/-643 newton-millimeters in Group C. With the numbers available, no significant differences could be detected among these values. The mean extraction torque was 253+/-175 newton-millimeters in Group A, 3360+/-1260 newton-millimeters in Group B, and 1720+/-1030 newton-millimeters in Group C (p = 0.002 for Group A compared with Group B, p = 0.017 for Group A compared with Group C, and p = 0.03 for Group B compared with Group C). The extraction torque was significantly lower than the corresponding insertion torque in both Group A (p < 0.001) and Group C (p = 0.003); no significant difference could be found, with the numbers available, in Group B (hydroxyapatite-coated pins). At sixty times magnification, direct contact was seen along a mean of 16+/-9 per cent of the bone-pin interface in Group A, 30+/-12 per cent of the interface in Group B, and 28+/-15 per cent of the interface in Group C (p = 0.042 for Group A compared with Group C). However, at 10,000 times magnification, direct bone-pin contact was found only in Group B.
对三种用于外固定针的表面进行了比较。108根5/6毫米的不锈钢锥形针被分为三组：36根保持未涂层状态（A组），36根用羟基磷灰石进行等离子喷涂（B组），36根用钛进行等离子喷涂（C组）。将这些针植入18只绵羊的左胫骨，每只绵羊接受同一组的6根针。然后在这些针上组装一个单侧固定器。暴露胫骨骨干中部的内侧部分，并去除一段5毫米长的骨圆柱体，以便让骨 - 针界面承受负荷。术后六周，X线片显示A组29个针道出现骨质稀疏，B组15个，C组30个（A组与B组相比p = 0.021，B组与C组相比p = 0.016）。A组的平均最终插入扭矩（及标准差）为4360±1050牛顿 - 毫米，B组为3420±676牛顿 - 毫米，C组为3740±643牛顿 - 毫米。就现有数据而言，这些值之间未检测到显著差异。A组的平均拔出扭矩为253±175牛顿 - 毫米，B组为3360±1260牛顿 - 毫米，C组为1720±1030牛顿 - 毫米（A组与B组相比p = 0.002，A组与C组相比p = 0.017，B组与C组相比p = 0.03）。A组（p < 0.001）和C组（p = 0.003）的拔出扭矩均显著低于相应的插入扭矩；就现有数据而言，B组（羟基磷灰石涂层针）未发现显著差异。在60倍放大倍数下，A组骨 - 针界面平均有16±9%可见直接接触，B组为30±12%，C组为28±15%（A组与C组相比p = 0.042）。然而，在10000倍放大倍数下，仅在B组发现骨 - 针直接接触。
