Comparison of histological grading to Fourier transform infrared imaging analysis of cartilage repair tissue

Repair of cartilage after injury is challenging, and evaluation of progression of repair could be helpful towards clinical management. Histology is the traditional method used to assess cartilage repair, but requires a biopsy. Here, we assess whether histological information obtained from cartilage repair tissue in an animal model can be correlated to FTIR parameters obtained from the same tissue. A strong relation between the two would support the use of FTIR fiber optic assessment as a clinical tool. Correlations were found between histological tissue score and FTIR imaging parameters of collagen quantity and collagen integrity (p=0.051 and 0.042, respectively). Infrared fiber optic probe spectra obtained from the repair tissue were evaluated for use as predictors of repair or normal tissue, and histological tissue score as well. Repair tissue was correctly distinguished from normal tissue in 47 out of 69 tissues. A partial least squares (PLS) model was also generated where spectra were used to predict histology score (out of a possible best score of 24) with a root mean square error (RMSE) of calibration of 1.70, and an RMSE of validation of 3.59. Together, these data show the potential for an FTIR-based determination of cartilage repair tissue quality.