Patella sleeve fractures occur most commonly in children aged 8-12. This injury involves an avulsion of cartilage (and sometimes a small piece of bone) from the inferior pole of the patella. These fractures may be missed on plain radiographs if there is no obvious bony injury. Radiographs will typically show an effusion, patella alta, and possibly a bony avulsion. In uncertain cases, an MRI is useful to define the extent of injury. Treatment for displaced sleeve fractures involves open reduction and fixation of the injury to restore the extensor mechanism. The article by Zionts reviews the diagnosis and management of fractures about the distal femur, proximal tibia, and patella in children.
Zionts LE: Fractures around the knee in children. J Am Acad Orthop Surg 2002;10:345- 355
PMID:12374485 (Link to Abstract)
Sponseller PD, Stanitski CL: Fractures and dislocations about the knee, in Beaty JH, Kasser JR: Rockwood and Wilkins’ Fractures in Children, ed 5. Philadelphia, PA, Lippincott Williams & Wilkins, 2001, pp 1029-1033