Relationship between the shape of tibial spurs on X-ray and meniscal changes on MRI in early osteoarthritis of the knee.

OBJECTIVE

The purpose of this study was to evaluate the relationship between the shape of tibial spurs on plain X-rays and the meniscal changes on magnetic resonance imaging (MRI) in early osteoarthritis of the knee.

MATERIALS AND METHODS

Sixty-three patients (age range, 40 to 59 years; average, 51.8) underwent X-ray and MRI examinations of their knees. Ligament injuries caused by trauma and Kellgren Radiographic Grades III and IV on X-ray were excluded. The shapes of the medial and lateral tibial spurs on X-ray were classified into four types: (a) normal type; (b) horizontal type, in which the spur protruded horizontally; (c) upward type, in which the spur protruded upward; and (d) downward type, in which the spur protruded downward. The femorotibial angle (FTA) on the X-rays was also measured. The medial and lateral meniscal displacement rates on MRI were measured by the proportion by which the meniscal lesion protruded from the edge of the tibial joint surface to the overall meniscal width. The medial and lateral meniscal signal changes on MRI were classified into three types: (a) normal type; (b) intrameniscal type, which showed a high signal within the meniscus; and (c) tear type, which showed a high signal extending to the tibial joint surface. The relationships between the shape of the medial and lateral tibial spur classification on X-ray, the medial and lateral meniscal displacement rates on MRI, the medial and lateral meniscal signal changes on MRI and the FTA were evaluated statistically.

RESULTS

Statistically significant correlations were observed between the medial tibial spur classification on X-ray, the medial meniscal displacement rate on MRI and the medial meniscal signal change classification on MRI. In the downward type of medial tibial spur, the medial meniscal displacement rate (50.46+/-17.95%) and the percentage (8 out of 8 cases; 100%) involving the tear type of medial meniscus were greater than the other types. Statistical significance was not observed among the lateral tibial spur classification on X-ray, the lateral meniscal displacement rate on MRI and the lateral meniscal signal change classification on MRI. However, in the horizontal type of lateral tibial spur, the percentage (7 out of 10 cases; 70%) involving the tear type of lateral meniscus was greater than the other types. Correlations tended to be observed between the medial meniscal displacement rate on MRI and the FTA.

CONCLUSIONS

In this study, there was a relationship between the shape of the tibial spur on X-ray and the meniscal changes on MRI in early osteoarthritis of the knee. The shape of the medial tibial spur on X-ray can be a useful indicator for predicting the progression of osteoarthritis of the knee. A downward type of medial tibial spur classification on X-ray may be a risk factor for developing severe osteoarthritis of the knee.