We report on a 20-year-old female patient with a fracture of the patella after she fell on"black ice" 2 months after medial patellofemoral ligament (MPFL) reconstruction for patellar instability. For reconstruction of the MPFL, a single hamstring tendon graft was passed through the medial intermuscular septum and was fixed to the superomedial pole of the patella. The fracture was reduced by wire cerclage. Intraoperatively it was shown that the fracture line went through the patellar drill hole. No complications occurred during the further postoperative period. The literature contains only a few case reports describing fractures of the patella after MPFL reconstruction without any specific trauma. In this case, an interruption in blood supply with resulting avascular necrosis was suspected as a causal factor.