Joint Space Width, but not Osteophyte Thickness, is a Reliable Indicator of Degeneration of Lateral Knee Joint Cartilage.

In this histologically controlled in vitro study, we evaluated the validity of plain radiography for the assessment of lateral knee joint cartilage degeneration (25 specimens). We examined the correlation between histological grade and radiography findings along with patient demographics. Our study indicated that the Mankin score had a significant inverse correlation with middle joint space width (JSW ; r=-0.19,P=0.02), but not with inner and outer JSW (inner : r=-0.11,P=0.10, outer : r=-0.14,P=0.06) under a non-weight bearing condition. The Mankin score had a significant inverse correlation with middle and outer JSW (middle : r=-0.17,P=0.04, outer : r=-0.14,P=0.04), but not with inner JSW (inner : r=-0.15,P=0.06) under valgus stress. There was no significant correlation between the Mankin score and osteophyte thickness (r=0.004,P=0.76). We also examined the correlation with patient demographics. We found that only the preoperative femorotibial angle had a significant inverse correlation with the Mankin score. These results indicate that JSW, but not osteophyte thickness, is reliable for evaluating lateral femoral cartilage degeneration.