Bone scintigraphy in patients with bipartite patella.

This study was performed to assess the diagnostic value of bone scintigraphy to differentiate symptomatic bipartite patella from asymptomatic bipartite patella. Thirty-seven bipartite patellae (15 symptomatic and 22 asymptomatic) were evaluated by bone scintigraphy. Bone scintigraphic activity in bipartite patella was classified into the following four groups. Group A: Eleven bipartite patellae (10 symptomatic and 1 asymptomatic) demonstrated physiological and marked uptake at the epiphysio-metaphysial junction of the distal femur in bone scintiscans. Therefore, high scintigraphic uptake in the bipartite patella was difficult to distinguish from such uptake due to overlap. Group B: Five bipartite patellae (4 symptomatic and 1 asymptomatic) demonstrated both physiologically high scintigraphic uptake at the epiphysio-metaphysial junction of the distal femur and high scintigraphic uptake in the bipartite patella. Group C: Seventeen bipartite patellae (1 symptomatic and 16 asymptomatic) demonstrated abnormally high scintigraphic uptake in the bipartite patella. Group D: Four asymptomatic bipartite patellae did not demonstrate an abnormally high scintigraphic uptake. After excluding Group A, the proportion of positive bone scans in bipartite patella was 84.6% (22 of 26 patellae). Similarly, after excluding Group A, the proportion of positive bone scans in symptomatic bipartite patella was 100% (5 of 5 patellae) and in asymptomatic bipartite patella 81.0% (17 of 21 patellae). Statistical analysis using Fisher's exact test showed no significant differences in the proportion of positive bone scans between both groups (P = 0.5457). In conclusion, abnormally high scintigraphic uptake is frequent findings in both symptomatic and asymptomatic bipartite patella, and bone scintigraphy is not useful to differentiate between them. Therefore, surgical treatment should not be considered based only on scintigraphic findings.