Background: 

Simple elbow dislocation occurs at an incidence of 2.9 to 5.21 dislocations per 100,000 person-years, with as many as 62% of these patients experiencing long-term elbow joint contracture, stiffness, and/or pain. Poor outcomes and the need for secondary surgical intervention can often be prevented nonoperatively with early or immediate active mobilization and physical therapy. However, immobilization or limited mobilization may be necessary following trauma, and it is unknown how different periods of immobilization affect pathological changes in elbow joint tissue and how these changes relate to range of motion (ROM). The purpose of this study was to investigate the effects of varying the initiation of free mobilization on elbow ROM and histological features in an animal model of elbow posttraumatic joint contracture.

Methods: 

Traumatic elbow dislocation was surgically induced unilaterally in rats. Injured forelimbs were immobilized in bandages for 3, 7, 14, or 21 days; free mobilization was then allowed until 42 days after injury. Post-mortem joint ROM testing and histological analysis were performed. One-way analysis of variance was used to compare ROM data between control and injured groups, and Pearson correlations were performed between ROM parameters and histological outcomes.

Results: 

Longer immobilization periods resulted in greater ROM reductions. The anterior and posterior capsule showed increases in cellularity, fibroblasts, adhesions, fibrosis, and thickness, whereas the measured outcomes in cartilage were mostly unaffected. All measured histological characteristics of the capsule were negatively correlated with ROM, indicating that higher degrees of pathology corresponded with less ROM.

Conclusions: 

Longer immobilization periods resulted in greater ROM reductions, which correlated with worse histological outcomes in the capsule in an animal model of posttraumatic elbow contracture. The subtle differences in the timing of ROM and capsule tissue changes revealed in the present study provide new insight into the distinct timelines of biomechanical changes as well as regional tissue pathology.

Clinical Relevance: 

This study showed that beginning active mobilization 3 days after injury minimized posttraumatic joint contracture, thereby supporting an immediate-motion clinical treatment strategy (when possible). Furthermore, uninjured but pathologically altered periarticular tissues near the injury location may contribute to more severe contracture during longer immobilization periods as the disease state progresses.

中文翻译：

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肘关节脱位后的早期关节使用限制了创伤后关节挛缩的运动范围损失和组织病理学

背景： 

单纯性肘关节脱位的发生率为每 10 万人年 2.9 至 5.21 例，其中多达 62% 的患者经历长期肘关节挛缩、僵硬和/或疼痛。通过早期或立即主动活动和物理治疗，通常可以通过非手术方式预防不良结果和二次手术干预的需要。然而，创伤后可能需要固定或有限活动，并且尚不清楚不同时期的固定如何影响肘关节组织的病理变化以及这些变化与运动范围（ROM）有何关系。本研究的目的是调查肘部创伤后关节挛缩动物模型中不同的自由活动起始时间对肘关节活动度和组织学特征的影响。

方法： 

通过手术在大鼠中单侧诱发外伤性肘关节脱位。受伤的前肢用绷带固定3、7、14或21天；然后允许自由活动直至受伤后 42 天。进行了尸检联合ROM测试和组织学分析。使用单因素方差分析来比较对照组和受伤组之间的 ROM 数据，并在 ROM 参数和组织学结果之间进行 Pearson 相关性分析。

结果： 

较长的固定时间会导致活动度减少更多。前囊和后囊显示细胞结构、成纤维细胞、粘连、纤维化和厚度增加，而软骨的测量结果大多不受影响。所有测量到的被膜组织学特征均与 ROM 呈负相关，表明病理程度越高，ROM 越少。

结论： 

较长的固定时间会导致关节活动度降低幅度更大，这与创伤后肘部挛缩动物模型中关节囊的组织学结果较差相关。本研究揭示的 ROM 和囊组织变化时间的细微差异为生物力学变化和区域组织病理学的不同时间线提供了新的见解。

临床相关性： 

这项研究表明，受伤后 3 天开始主动活动可以最大限度地减少创伤后关节挛缩，从而支持立即行动的临床治疗策略（如果可能）。此外，随着疾病状态的进展，受伤位置附近未受伤但发生病理改变的关节周围组织可能会在较长的固定时间内导致更严重的挛缩。