骨性和软组织性髌骨脱位模型中滑车发育的实验研究

Experimental research on the trochlear dysplasia with bony and soft tissue model of patellar dislocation

目的通过股骨截骨术增大股骨前倾角和髌骨内外侧软组织失平衡手术制作髌骨脱位模型,观察股骨滑车局部形态和骨小梁结构的变化。方法取40只3个月龄的新西兰幼兔,分别对其右膝进行两种手术方式(每组20只):①截骨组,接受股骨旋转截骨术,股骨远端内旋来增大股骨前倾角;②软组织组,行髌骨内侧支持带松解和外侧支持带紧缩缝合术。所有左膝作为正常对照组。术后观察4个月至骨骼成熟,将股骨远端进行Micro-CT扫描,测量滑车形态:外侧髁、滑车沟和内侧髁的高度,滑车沟角,滑车的外侧和内侧关节面倾斜角等,并对骨小梁进行分析:骨体积分数、骨小梁厚度、骨小梁数量、骨小梁分离度和骨密度等。相关指标的结果进行组间比较。结果截骨组中1例发生髋关节脱位,而髌骨未发生脱位;3例在屈膝状态下出现完全性的髌骨脱位;16膝在膝关节被动伸直时,髌骨发生脱位。软组织组中15膝在屈膝状态下出现完全性的髌骨脱位,5膝未发生髌骨脱位。截骨组的股骨滑车在滑车入口处伴有局部的突起形成,称为"骨突",而滑车关节面比较光滑,未出现明显的软骨破裂等,而软组织组的股骨滑车未见"骨突"形成,滑车关节面出现软骨破裂、缺损等关节炎表现。与对照组相比,截骨组和软组织组的滑车均变浅和变宽,滑车沟高度和滑车沟角变大,但两组比较没有统计学差异。与对照组相比,截骨组骨小梁发生汇聚,内侧髁和外侧髁的骨小梁厚度增大,内侧髁骨小梁数量减少,而软组织组表现为骨质疏松,内侧髁和外侧髁的骨体积分数、骨小梁厚度、骨小梁数量和骨密度都减少,骨小梁分离度增大。与软组织组相比,截骨组内侧髁和外侧髁的骨体积分数、骨小梁厚度、骨小梁数量和骨密度都较大,骨小梁分离度较小,差异有统计学意义。结论通过股骨截骨术增大股骨前倾角和髌骨内外侧软组织失平衡手术可成功构建髌骨脱位的骨性和软组织型模型,并继发形成不同的滑车形态学改变和骨小梁结构变化。

Objective To establish a model of patellar dislocation by femoral osteotomy or surgical release of medial retinaculum in immature rabbits,and observe morphological and trabecular microarchitectural changes in the trochlea.Methods Forty rabbits at 3 months of age were included.All right knees underwent surgery,20 knees were treated with femoral osteotomy and internal rotation of distal femur to increase femoral anteversion angle(Osteotomy group,OS group),and another 20 knees were treated with surgical release of medial retinaculum and overlap suture of lateral retinaculum(Soft tissue group,ST group).All left knees were acting as internal controls.Micro-CT scans for distal femur were acquired after 4 months post surgery.the height of Medial,central,and lateral trochlear,sulcus angle,and lateral and medial trochlear slope were measured to describe the trochlear morphology,and bone volume fraction(BV/TV),trabecular thickness(Tb.Th),trabecular number(Tb.N),trabecular spacing(Tb.Sp),and bone mineral density(BMD)were calculated to evaluate the microarchitectural structure.All parameters were compared between groups.Results In OS group,one rabbit sustained a hip dislocation without patellar dislocation.Three knees developed complete patellar dislocation in daily flexion position,and the remaining 16 patellae were dislocated when the knee was placed in the maximal extension position.In ST group,15 knees were complete patellar dislocation in daily flexion position,and 5 knees were without dislocation.A local boss was formed proximal to the entrance of the groove and the articular cartilage was smooth,and no obvious osteoarthritis was observed in OS group.In ST group no boss was formed,while obvious cartilage degeneration and defect was seen.Compared to the control group,the central trochlear height and sulcus angle were greater in both groups,but without significant difference between the two groups.The Tb.Th was increased in both medial and lateral condyle,and Tb.N was decreased in medial condyle compared with its control knees in OS group.The BV/TV,Tb.Th,Tb.N and BMD were decreased and Tb.Sp was increased in both medial and lateral condyle compared with its control knees in ST group.Compared to the OS group,the BV/TV,Tb.Th,Tb.N and BMD were smaller and Tb.Sp was greater in both medial and lateral condyle in ST group,with significant differences.Conclusion The model of patellar dislocation could be successfully achieved by femoral rotational osteotomy to increase femoral anteversion or surgical release of medial retinaculum and overlap suture of lateral retinaculum,and subsequent morphological and trabecular microarchitectural changes in the trochlea are different.Different bony and soft tissue factors should be addressed for different patients with patellar dislocation in clinical practice.