Epidemiology
- Uncommon, as the patella is largely cartilaginous in young children
- Sleeve fracture occurs at about 8 to 12 years
Pathology
- Sleeve fracture is avulsion of a large cartilage sleeve with a small fleck of bone from the inferior pole
Clinical Features
- Pain and swelling after jumping or quadriceps contraction
- Palpable gap at the inferior pole
- Unable to perform a straight leg raise
Investigations
- Lateral radiograph shows patella alta and a small inferior bony fleck
- Radiographs underestimate the cartilage fragment
- MRI or ultrasound confirms the sleeve fracture
Differential Diagnosis
- Bipartite patella, usually superolateral and often bilateral
- Sinding-Larsen-Johansson disease
Management
- Undisplaced fractures with intact extensor mechanism treated in a cylinder cast
- Displaced fractures treated with tension band wire
- Sleeve fractures need open reduction and fixation, often with sutures
Complications
- Missed sleeve fracture leads to an elongated patella and extensor lag
- Patella alta
- Symptomatic hardware
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.