Objective The aim of this study was to clarify the histological effects of tibial plateau levelling osteotomy on cranial cruciate ligament degeneration induced by excessive tibial plateau angle.

Study Design Five female Beagles were used to bilaterally create excessive tibial plateau angle models surgically. A second tibial plateau levelling osteotomy was performed 11 months after the first surgery on the right stifle (tibial plateau levelling osteotomy group), and a sham operation that did not change the tibial plateau angle was performed on the left stifle (excessive tibial plateau angle group). At 6 months after the second surgery, the dogs were euthanatized. The cranial cruciate ligament was stained with haematoxylin–eosin to assess the cell density, Alcian-Blue to assess proteoglycans and Elastica-Eosin to assess elastic fibres, and immunohistochemically stained to assess type I (COL1) and type II collagen and SRY-type HMG box 9 (SOX9) expression.

Results In each group, the cranial cruciate ligament degeneration, especially on the tibial side, including the presence of Alcian-Blue- and Elastica-Eosin-positive regions, decreased in COL1-positive regions, and enhancement of SOX9 expression was observed. Besides, compared with the tibial plateau levelling osteotomy group, the excessive tibial plateau angle group showed increases in Alcian-Blue- and Elastica-Eosin-positive regions and a decrease in the COL1-positive regions.

Conclusion The results suggested that excessive tibial plateau angle-induced cranial cruciate ligament degeneration can be suppressed by reducing the biomechanical load on the cranial cruciate ligament by performing tibial plateau levelling osteotomy.

目的 本研究旨在阐明胫骨平台平整截骨术对胫骨平台角度过大致颅交叉韧带退变的组织学影响。

研究设计 五只雌性小猎犬被用于通过手术双侧创建过度的胫骨平台角度模型。右侧膝关节第一次手术后11个月进行第二次胫骨平台平整截骨（胫骨平台平整截骨组），左侧膝关节进行不改变胫骨平台角度的假手术（胫骨平台角度过度组） ）。在第二次手术后 6 个月，对狗实施安乐死。颅交叉韧带用苏木精-伊红染色以评估细胞密度，Alcian-Blue 以评估蛋白聚糖和 Elastica-Eosin 以评估弹性纤维，免疫组织化学染色以评估 I 型 (COL1) 和 II 型胶原蛋白和 SRY 型 HMG框 9 (SOX9) 表达式。

结果 在各组中，COL1阳性区域的颅交叉韧带退化，尤其是胫骨侧，包括Alcian-Blue-和Elastica-Eosin阳性区域的存在减少，并且观察到SOX9表达增强。此外，与胫骨平台平整截骨组相比，胫骨平台角度过大组Alcian-Blue-和Elastica-Eosin阳性区域增加，COL1阳性区域减少。

结论 提示胫骨平台矫直截骨术降低颅交叉韧带的生物力学负荷可抑制胫骨平台过度角引起的颅交叉韧带退变。