Abstract
We report two cases of screw failure with no traumatic episode after vastus lateralis release and screw placement for treatment of painful bipartite patella. Case 1 was a 26-year-old man with left painful bipartite patella categorized into Saupe III and treated with vastus lateralis release and screw placement to attach the accessory bone. After three months, the screw failed with no traumatic episode. Case 2 was a 14-year old man with bilateral painful bipartite patella categorized into Saupe III and treated with vastus lateralis release and screw placement to attach the accessory bones. After two or six months, the screw on the left or right side failed with no traumatic episode, respectively. We speculate that the screws may have failed due to the following reasons; first, releasing the vastus lateralis loosened an accessory bone tethered by vastus lateralis, then, the accessory bone was attached with a cancellous screw to the main portion of the patella. Afterwards, it was gradually driven forward by the peak of the femoral lateral condyle based on the configuration of the patella-femoral joint. Eventually, the screw placed in the accessory bone failed.
