Non-invasive determination of structural changes in articular cartilage immediately after impact and rehydration provides insight into the response and recovery of the soft tissue, as well as provides a potential methodology for clinicians to quantify early degenerative changes.

In this study, we use polarisation-sensitive optical coherence tomography (PS-OCT) to examine subtle alterations of the optical properties in healthy and early-stage degenerate articular cartilage immediately after impact loading to identify structurally relevant metrics required for understanding the mechanical factors of osteoarthritic initiation and progression.

A custom-designed impact testing rig was used to deliver 0.9 J and 1.4 J impact energies to bovine articular cartilage. A total of 52 (n=26 healthy, n=26 mildly degenerate) cartilage-on-bone samples were imaged before, immediately after, and 3 h after impact. PS-OCT images were analyzed to assess changes relating to surface irregularity, optical attenuation, and birefringence. Mildly degenerate cartilage exhibits a significant change in birefringence following 1.4 J impact energies compared to healthy samples which is believed to be attributable to degenerate cartilage being unable to fully utilise the fluid phase to distribute and dampen the energy. After rehydration, the polarisation-sensitive images appear to ‘optically-recover’ reducing the reliability of birefringence as an absolute metric. Surface irregularity and optical attenuation encode diagnostically relevant information and may serve as markers to predict the mechanical response of articular cartilage.

PS-OCT with its ability to non-invasively image the sub-surface microstructural abnormalities of cartilage presents as an ideal modality for cartilage degeneration assessment and identification of mechanically vulnerable tissue.

冲击和补液后立即无创确定关节软骨的结构变化，不仅可以洞察软组织的反应和恢复情况，还可以为临床医生提供量化早期退行性变化的潜在方法。

在这项研究中，我们使用偏振敏感光学相干断层扫描（PS-OCT）检查撞击负荷后立即在健康和早期简并关节软骨中光学性质的细微变化，以识别理解结构力学因素所需的结构相关指标骨关节炎的发生和发展。

使用定制设计的冲击试验台向牛关节软骨提供0.9 J和1.4 J的冲击能量。在撞击前，撞击后和撞击后3小时对总共52个（n = 26健康，n = 26轻度退化）骨软骨样品成像。分析了PS-OCT图像，以评估与表面不规则性，光学衰减和双折射有关的变化。与健康样品相比，轻度简并软骨在1.4 J冲击能量后显示出双折射的显着变化，这被认为可归因于简并软骨无法充分利用液相来分配和衰减能量。再水化后，偏振敏感图像似乎“光学恢复”，从而降低了双折射作为绝对度量的可靠性。

PS-OCT具有无创成像软骨下表面微结构异常的能力，是软骨退化评估和鉴定机械脆弱组织的理想方式。