Previous studies using nonlinear microscopy have demonstrated that osteoarthritis (OA) is characterized by the gradual replacement of Type II collagen with Type I collagen. The objective of this study was to develop a prototype nonlinear laser scanning microendoscope capable of resolving the structural differences of collagen in various orthopaedically relevant cartilaginous surfaces. The current prototype developed a miniaturized femtosecond laser scanning instrument, mounted on an articulated positioning system, capable of both conventional arthroscopy and second-harmonic laser-scanning microscopy. Its optical system includes a multi-resolution optical system using a gradient index objective lens and a customized multi-purpose fiber optic sheath to maximize the collection of backscattered photons or provide joint capsule illumination. The stability and suitability of the prototype arthroscope to approach and image cartilage were evaluated through preliminary testing on fresh, minimally processed, and partially intact porcine knee joints. Image quality was sufficient to distinguish between hyaline cartilage and fibrocartilage through unique Type I and Type II collagen-specific characteristics. Imaging the meniscus revealed that the system was able to visualize differences in the collagen arrangement between the superficial and lamellar layers. Such detailed in vivo imaging of the cartilage surfaces could obviate the need to perform biopsies for ex vivo histological analysis in the future, and provide an alternative to conventional external imaging to characterize and diagnose progressive and degenerative cartilage diseases such as OA. Moreover, this system is readily customizable and may provide a suitable and modular platform for developing additional tools utilizing femtosecond lasers for tissue cutting within the familiar confines of two or three portal arthroscopy techniques.

中文翻译：

---

使用原型非线性显微内窥镜对半月板和关节软骨进行二次谐波显微术的临床前转换

先前使用非线性显微镜的研究表明，骨关节炎 (OA) 的特征是 II 型胶原蛋白逐渐被 I 型胶原蛋白替代。本研究的目的是开发一种原型非线性激光扫描显微内窥镜，能够解决各种骨科相关软骨表面胶原蛋白的结构差异。目前的原型开发了一种微型飞秒激光扫描仪，安装在铰接式定位系统上，能够进行传统关节镜检查和二次谐波激光扫描显微镜检查。其光学系统包括一个多分辨率光学系统，使用梯度指数物镜和定制的多用途光纤鞘，以最大限度地收集反向散射光子或提供关节囊照明。通过对新鲜、最少加工和部分完整的猪膝关节的初步测试，评估了原型关节镜接近和成像软骨的稳定性和适用性。通过独特的 I 型和 II 型胶原特异性特征，图像质量足以区分透明软骨和纤维软骨。半月板成像显示该系统能够可视化表层和层状层之间胶原排列的差异。软骨表面的这种详细的体内成像可以避免将来进行活组织检查以进行离体组织学分析，并提供传统外部成像的替代方法，以表征和诊断进行性和退行性软骨疾病，如 OA。而且，