The validity of in vivo ultrasonographic grading of osteoarthritic femoral condylar cartilage: a comparison with in vitro ultrasonographic and histologic gradings.

OBJECTIVES

To establish an ultrasonographic (US) grading for semiquantitative evaluation of the femoral condylar cartilage of knee osteoarthritis (OA), in vivo, and compare the in vivo US grading with the in vitro US and histologic gradings.

DESIGN

Ninety-five patients going to receive total knee arthroplasty because of OA of the knee were recruited. US examination was performed in vivo in the day before operation using a grading system including parameters of margin sharpness, clarity and thickness. Specimens of the medial and lateral distal femoral condyles taken during the operation were graded with in vitro US and histologic evaluation. The correlation between the in vivo US and in vitro US as well as between the in vivo US and histologic gradings was analyzed.

RESULTS

In 172 femoral condyles (including medial and lateral ones), the distribution of grading ranged from Grade 1 to 6 in in vivo US and from Grade 1 to 4 in histologic examination. The in vivo US grading was significantly correlated to in vitro US grading over anterior and middle areas (p<0.001, Rho=0.35 and 0.45, respectively) and histologic grading over these two areas (p<0.001, Rho=0.40 and 0.36, respectively). When the cases with maximal angle of knee flexion less than 120 degree were excluded, the correlation was better.

CONCLUSIONS

The significant correlation between in vivo US and histologic gradings might permit semi-quantitative in vivo US assessment of osteoarthritic femoral condylar cartilage.