A digital method of measuring cartilage defects under an arthroscope.

Measurements of cartilage defect size under an arthroscope are essential for prognosis and treatment decisions. A new method called arthroscopic measurement by computer graphics (ACG) was developed to accurately calculate the size of the cartilage under an arthroscope. This study aimed to validate the accuracy and utility of this method. In this controlled laboratory study, the ACG method was validated by measuring the sizes of three cartilage defects in a knee joint of a pig, using the following techniques: traditional arthroscopic measurement by ruler (TAR), ACG, incised measurement by computer graphics (ICG), and incised measurement by ruler (IR, control, gold standard). Measurements were conducted by two blinded trained observers. Intra- and inter-observer variabilities were determined by calculating the intra-class correlation coefficient (ICC). Consistency among TAR, ACG, ICG and IR was analyzed using the command "Concord" in Stata. For arthroscopic measurements using ACG and ICG, the overall ICC intra- and inter-observer values were 0.99 and 0.98, respectively, which showed excellent reproductivity. The concord value showed consistency of various approaches relative to the gold standard method. The average concord value for TAR was 0.813, and the average concord value for ACG and ICG was 0.886 and 0.917, respectively. ACG utilizes computer graphics for measuring the size of cartilage defects of any size under an arthroscope, without reconditioning the injured cartilage. ACG showed excellent intra- and inter-observer reproducibility and satisfactory accuracy. This method would make it possible to more accurately match the graft with the defect, thereby facilitating cartilage repair. AJTR