Dislocated Extensor Mechanism in a Child With Bilateral Absent Patella Without Other Congenital Abnormalities

CASE: A 10-year-old boy presented with bilateral absent patella and dislocation of the extensor mechanism in the left lower extremity. He underwent a lateral release and medial plication of the extensor mechanism with a Roux-Goldthwait procedure, followed by casting and bracing treatment. The patient fully recovered with a return to sports and improved active range of motion. CONCLUSION: Bilateral absent patella without other congenital anomalies is an exceedingly rare condition and can be accompanied by a dislocation of the extensor mechanism. Treatment should address functional limitations, including extensor mechanism dislocation, when present.