Biomechanical analyses on effects of stress deprivation on the mechanical properties of the frozen anterior cruciate ligament.

1.我们研制了一种液氮循环的螺旋形冷冻探针，用于犬前交叉韧带（ACL）的原位冷冻。为了了解冷冻探针的能力，我们冷冻了4只成年狗的头部。冷冻后行显微镜观察及细胞培养检测活细胞。结果：1.冷冻前交叉韧带中未发现活细胞，证明原位冷冻可杀死前交叉韧带的所有成纤维细胞.用自行设计的螺旋冷冻探针对28只成年比格犬的耳蜗进行了原位冷冻。所有成纤维细胞死亡后，用生理盐水解冻。通过穿透空心扩髓钻，用圆柱形骨块从胫骨上插入每个AOL的胫骨插入物。将狗分为两组。在第一组中，骨块在解剖学上复位（Sham组）。在第二组中，通过将骨块向近端方向移位3 mm（松弛组）来完全松弛AOL。日 关于我们 然后用界面螺钉将每个骨块牢固固定。比较了Sham组和Relax组原位冷冻骨力学性能和超微结构的变化.仅在12周时Relax组的AOL横截面积显著大于Sham组。Relax组各时间点的拉伸强度和切线模量均显著低于Sham组。两组在各个时期的破坏应变均无显著性差异.对4只狗的睾丸进行了超微结构分析。术后6周，Sham组成纤维细胞进入原位冷冻ACL的浅层，而Relax组卵圆核细胞进入中间间隙。12周时，Sham组细胞核呈梭形，Relax组细胞核呈椭圆形，但各组AOL实质内均可见成纤维细胞。少

1. We developed helical cryoprobe in which liquid nitrogen was circulated to perform in situ freezing of the canine anterior cruciate ligament (ACL). To know the ability of the cryoprobe we froze the ACLs of 4 adult dogs. After freezing, the ligaments were investigated with microscope and cell culture to detect living cell. No living cell was found in the frozen ACL.It was proved that the in situ freezing killed all fibroblasts of the AOL.2. The ACLs of the 28mature beagle dogs were frozen in situ with the specially designed helical oryoprobe. After all fibroblasts died, the ACLs were thawed out with physiological saline. The tibial insertion of each AOL was made tree from the tibia with a cylindrical bone block by penetrating a hollow reamer. The dogs were divided in two groups. At the first group, the bone block was reduced anatomically (Sham group). At the second group, the AOL was completely relaxed by translocating the bone block to the proximal direction by 3 mm (Relax group). Th … More en, the each bone block was firmly fixed with an interference screw. The differences of the in situ frozen ACLs between the Sham and the Relax groups were investigated about the changes of mechanical properties and ultrastructure.3. The cross sectional area of the AOL in Relax group was significantly greater than that in Sham group only at 12 weeks. The tensile strength and the tangent modulus in Relax group were significantly lower than that in Sham group at each period. There were no significant differences in the strain at failure between the two groups at each period.4. The ACLs of four dogs were analyzed ultrastructurally. At 6 weeks after surgery, fibroblasts entered into the superficial substance of the in situ frozen ACL in the Sham group, although cells with oval nucleus entered into the *tersubstancial space in the Relax group. At 12 weeks, the fibroblasts were found at all the substance of the AOL in each group, although the shape of the nucleus of entered cell was spindle in the Sham group and oval in the Relax group. Less