Tx and Followup:
Tripartite patella is a normal variant of patella which include bipartite or other multi-partite patella. Radiographs of these show smooth cortical surfaces and characteristic location on the superolateral margin of the patella. Flake-like ossification centers also appear on the anterior and occasionally on the inferior surface of the patella. The fragment margins are sclerotic and round and not as sharply defined as in fracture â€“ failing to fit perfectly. It is bilateral in approximately 80% of cases.
On the other hand, patellar fractures occur with direct and indirect trauma, such as explosive quadriceps contraction. These fractures are often difficult to demonstrate and are best visualized on lateral and sunrise views. Fifty to 80 percent of patellar fractures are transverse, although they may be longitudinal when associated with a direct force. In patellar fracture, fragments have nonsclerotic, sharp margins and would fit perfectly together. The smaller segment or segments are usually located along the upper outer quadrant of the patella. These may be mistaken for fractures. In approximately 80% of the cases, the anomaly is bilateral. Flake-like ossification centers also appear on the anterior and occasionally on the inferior surface of the patella. Hematoma around quadriceps tendon and/or patellar ligament also is suggestive of fracture.