Design and validation of an automated dual-arm instrumented intravaginal dynamometer.

AIMS: (1) To present the design of a novel intravaginal dynamometer (IVD) capable of measuring vaginal closure force on both the anterior and posterior arms, (2) to use bench testing to validate the force, speed of arm opening, and positional accuracy of load measurement along the IVD arms, and (3) to present in vivo force measurements made with this device, comparing forces measured by the anterior and posterior arms. METHODS: IVD load measurements were validated against an Instron® Universal Tester, arm opening speeds were validated using video analysis, and position-load accuracy was validated against calibration weights. In vivo IVD data were acquired from female volunteers during passive opening and pelvic floor muscle contraction tasks. Anterior and posterior IVD arm force outcomes were compared. RESULTS: Forces measured by the IVD and Instron® exhibited a strong linear relationship with excellent model fit. The speed control system was valid when tested under physiological loading conditions, however smaller antero-posterior opening diameters (25 and 30 mm) exhibited some error. The loading position along the IVD arms had no effect on force outcomes. In vivo data exhibited differences between force outcomes measured at the anterior and posterior aspects of the vagina during active contraction and passive elongation of the pelvic floor muscles. CONCLUSIONS: This IVD design demonstrates valid load measurement and speed control during bench testing. Active and passive forces measured are consistent with the literature. With dual instrumented arms, this device allows for further investigation into the source of measured vaginal closure forces.

Pre-Clinical Translation of Second Harmonic Microscopy of Meniscal and Articular Cartilage Using a Prototype Nonlinear Microendoscope.

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.