查看更多>>摘要：目的 探索胫骨平台Hoffa骨折畸形愈合后膝关节内力学传导的变化，确定胫骨平台应力与畸形愈合之间的关系。 方法 取28具福尔马林防腐处理的膝关节标本，男性与女性各半，年龄为（51.4±9.5）岁。膝关节结构完整，屈伸活动无异常，X线检查排除骨质疏松、结核及可能影响骨质的疾病。膝关节标本分为1个对照组（正常完整胫骨）（n=4）与6个胫骨平台Hoffa骨折畸形愈合模型组，每组男女各半：3个垂直畸形愈合组（即V1组、V2组、V3组，分别为垂直向下移位1、2、3 mm，n=4）和3个分离畸形愈合组（即S3组、S5组、S7组，分别为分离移位3、5、7 mm，n=4）。在膝关节被动屈曲0°、30°、60°、90°、120°下施加600 N垂直载荷，利用压敏片分别测量膝关节内、外侧间室的应力大小。 结果 在600 N的垂直载荷下，当膝关节呈中立位（即屈曲0°）时，不同畸形愈合模型的胫骨平台内、外侧应力值与对照组差异均无统计学意义（P>0.05）。当膝关节屈曲角度增大到30°时，V3组和S7组的胫骨内侧平台应力均显著大于正常胫骨内侧平台应力，差异均有统计学意义（P<0.05）。膝关节屈曲角度为60°时，V3、S5、S7组内侧平台应力均显著大于对照组，且与对照组的差异较膝关节屈曲30°时增大，差异均有统计学意义（P<0.05）。膝关节屈曲角度为90°时，V2、V3、S5和S7组内侧平台应力显著大于对照组，差异有统计学意义（P<0.05）；而V3的胫骨外侧平台应力显著小于对照组，差异有统计学意义（P<0.05）。当膝关节屈曲角度进一步增大达到120°时，所有畸形愈合模型组内、外侧平台应力值与正常胫骨差异均有统计学意义（P<0.05），且相较于90°的差异值明显增高，差异均有统计学意义（P<0.05）。在600 N的垂直载荷下，对照组与所有畸形愈合组膝关节未弯曲（即0°）的情况下内、外侧平台的应力差异无统计学意义（P>0.05）。当膝关节屈曲角度的增大到30°时，对照组内、外侧平台的应力差异无统计学意义（P>0.05），但V3组和S7组内、外侧平台应力差异均有统计学意义（P<0.05）。当膝关节屈曲角度达到60°、90°、120°时，所有组内、外侧胫骨平台的应力比较差异均有统计学意义（P<0.05）。 结论 胫骨平台Hoffa骨折发生畸形愈合后膝关节应力峰值与畸形愈合程度、膝关节屈曲角度相关。轻度畸形愈合与正常膝关节的力学性能差异不大，但较大移位（垂直移位>2 mm，分离移位≥5 mm）会增加膝关节应力峰值，增加膝关节炎的风险。当畸形愈合程度确定时，膝关节屈曲角度增加会增大胫骨内外侧平台应力峰值的差异，增加膝关节炎的发生几率。 Objective To determine the relationship between tibial plateau stresses and malunion by exploring the changes in mechanical conduction in the knee joint after malunion of Hoffa fracture of the tibial plateau. Methods This study selected 28 knee joint specimens treated with formalin for preservation, half of which were from male and half from female individuals with an age of (51.4±9.5) years. Their structures were intact, and flexion-extension activities normal. X-ray examinations excluded osteoporosis, tuberculosis, and diseases that could have potentially affected bone quality. The knee specimens were divided into a control group (intact tibia) (n=4) and 6 groups of tibial plateau Hoffa fracture malunion model: 3 vertical malunion groups (groups V1, V2, and V3, with a vertical displacement of 1, 2, and 3 mm, respectively, n=4) and 3 separation malunion groups (groups S3, S5, and S7, with a separation displacement of 3, 5, and 7 mm, respectively), with half males and half females in each group. After a 600N vertical load was applied at passive knee flexions at 0°, 30°, 60°, 90°, and 120°, the stress levels in the medial and lateral compartments of the knee joint were measured using pressure-sensitive films. Results Under a vertical load of 600 N, when the knee joint was in a neutral position (flexion of 0°), the differences in the medial and lateral tibial plateau stress values were not statistically significant between the malunion models groups and the control group (P>0.05). When the knee flexion increased to 30°, the medial tibial plateau stress in the V3 and S7 groups was significantly greater than that in the control group (P<0.05). At a knee flexion of 60°, the medial plateau stress was significantly greater in the V3, S5 and S7 groups than that in the control group, and the differences were significantly greater than the comparisons at a knee flexion of 30° (allP<0.05). When the knee flexion was 90°, the medial plateau stress in the V2, V3, S5 and S7 groups was significantly greater than that in the control group (P<0.05), but the lateral tibial plateau stress in the V3 group was significantly smaller than that in the control group (P<0.05). When the knee flexion was further increased to 120°, the differences in the medial and lateral plateau stress values were statistically significant between all the malunion groups and the control group (P<0.05), and the differences significantly greater than the comparisons at a knee flexion of 90° (allP<0.05). Under a vertical load of 600 N, the differences in the stresses on the medial and lateral plateaus were not statistically significant between the control group and all the malunion groups at a knee flexion of 0° (P>0.05). When the knee flexion increased to 30°, the difference between the medial and lateral stresses was not statistically significant in the control group (P>0.05), but was statistically significant in the V3 and S7 groups (P<0.05). When the knee flexion reached 60°, 90°, and 120°, the differences between the medial and lateral tibial plateau stresses in all the groups were statistically significant (P<0.05). Conclusions The peak knee stresses after malunion of Hoffa fracture of the tibial plateau correlate with the severity of malunion and knee flexion angles. The mechanical properties are not significantly different between a mild malunion knee and a normal knee, but a significant displacement (vertical displacement >2 mm and separation displacement ≥5 mm) may increase the peak knee stresses to increase the risk of knee osteoarthritis. When the severity of malunion is certain, an increase in knee flexion angle increases the difference in the peak stress between the medial and lateral tibial plateaus, thus increasing the risk of knee osteoarthritis.
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