Introduction and Aims: Autologous chondrocyte implantation (ACI) is emerging as a leading technique for the treatment of articular cartilage defects. However, there exists some debate regarding which ACI technique is best able to regenerate hyaline cartilage. To this end, the development of a non-invasive technique enabling the examination of microstructure after ACI is essential.

Method: In this study, we have developed a novel 2D Laser Scanning Confocal Arthroscope (LSCA) in the assessment of articular cartilage and examined the microstructure of knee articular cartilage from rabbits and patients with total knee arthroplasty. The LSCA system consists of the LSA handheld probe, a Launch and Detection Unit (LDU) with a built in 488nm–514nm Krypton Argon Laser and Master Control unit (MCU). Human and rabbit knee articular cartilage stained with Fluoroscein (5g/L) and Acriflavine (0.5g/L) were used to examine the microstructure of cartilage by LSCA.

Results: By LSCA we have generated optical histology images of normal human and rabbit articular cartilage from the femoral condyle. Optical histology of normal articular cartilage tissue reveals typically smooth surface texture with relatively homogenous sub-surface distribution of viable chondrocyte cells. The general orientation of collagen fibres is occasionally visible in surface images. Optical histology of arthritic cartilage of humans showed clusters of round-shaped chondrocytes mixed with spindle-shaped cells. Surface cracking typically indicative of tissue damage is also evident by LSCA observation. Examination of rabbit knee six weeks after ACI showed high density of chondrocytes and homogeneous matrix on the site of the defect.

Conclusion: In short, we have shown the efficacy of LSCA in the non-destructive assessment of articular cartilage in vivo. Further study is required to evaluate the clinical significance of optical histology of LSCA.