Broadband reflectance spectral markers for monitoring PCL elongation under an arthroscopy-like configuration

Posterior cruciate ligament (PCL) repair lacks real-time quantitative evaluation. This study explores broadband reflectance spectroscopy under arthroscopy-like geometry to assess ligament elongation. Porcine PCLs were loaded while spectra were recorded at probe angles of 0°, 30°, and 45°. Reflectance slope and 680/620 nm ratio increased with elongation and remained angle-resilient within 620-680 nm, thereby identifying elongation-sensitive yet probe-angle-tolerant spectral markers. Mie scattering analysis supported the geometry-dependent response. These results establish, to the best of our knowledge, a systematic spectral basis for potential quantitative feedback on PCL elongation in arthroscopy with minimal modification.