Patellar sleeve fractures (also commonly, patellar sleeve avulsion fracture) represent chondral or osteochondral avulsion injury commonly at the inferior pole of the patella (including cartilage from the articular surface, as well as periosteum and cartilage over the dorsal surface).
Very rarely it can involve the upper pole 5.
This is an important diagnosis as the displaced bone-forming tissue will continue to grow and ossify, enlarging and possibly duplicating the patella.
Patellar sleeve fractures occur in the pediatric population between 8 and 16 years of age, with a peak incidence at 12.7 years, predominantly boys (3:1). Adolescents are more susceptible due to rapid growth, increased sports activity, and relative patella instability.
Unlike Sinding-Larsen-Johansson disease, these injuries are acute and result from sudden and forceful contraction of quadriceps muscle (indirect mechanism). Acute focal pain and tenderness occur at the time of the injury, and a palpable gap may be present.
Lateral knee x-rays demonstrate swelling at the lower pole of the patella and some degree of patella alta. If a small bony fragment has been avulsed with the cartilage, then this too may be seen. A joint effusion may not be present.
Ultrasound may be helpful in the absence of a radiographically visible fracture fragment. A disruption of the cartilage may be seen, and the degree of separation estimated. Ancillary findings of soft tissue edema, fluid, and hyperemia may be helpful.
MRI is critical if the diagnosis is suspected as the degree of chondral injury cannot be assessed on plain radiography, and coexistent extensor mechanism injury may be present.
Treatment and prognosis
Surgical treatment is recommended when there is significant displacement (>2 mm) of the displaced osteo/chondral fragment.
- 1. Dupuis CS, Westra SJ, Makris J et-al. Injuries and conditions of the extensor mechanism of the pediatric knee. Radiographics. 29 (3): 877-86. doi:10.1148/rg.293085163 - Pubmed citation
- 2. Hunt DM, Somashekar N. A review of sleeve fractures of the patella in children. (2005) The Knee. 12 (1): 3-7. doi:10.1016/j.knee.2004.08.002 - Pubmed
- 3. D G Bates, M T Hresko, D Jaramillo. Patellar sleeve fracture: demonstration with MR imaging. (1994) Radiology. 193 (3): 825-7. doi:10.1148/radiology.193.3.7972832 - Pubmed
- 4. Xie L, Xu H, Zhang L, Xu R, Guo Y. Sleeve fracture of the adult patella: Case report and review of the literature. (2017) Medicine. 96 (32): e7096. doi:10.1097/MD.0000000000007096 - Pubmed
- 5. Li Y, Yu H, Huang B, Zhang W, Wang Y, Liu X. Upper pole sleeve fracture of the patella secondary to patellar dislocation: A case report. (2019) Medicine. 98 (24): e16011. doi:10.1097/MD.0000000000016011 - Pubmed
Related Radiopaedia articles
The knee is a complex synovial joint that can be affected by a range of pathologies:
- bone and cartilage
- distal femoral condyle fracture
- tibial plateau fracture (classification)
- patella fracture
avulsion fractures of the knee
- Segond fracture
- reverse Segond fracture
- anterior cruciate ligament avulsion fracture
- posterior cruciate ligament avulsion fracture
- arcuate complex avulsion fracture (arcuate sign)
- biceps femoris avulsion fracture
- iliotibial band avulsion fracture
- semimembranosus tendon avulsion fracture
- Stieda fracture (MCL avulsion fracture)
- patella fracture
- chronic avulsion injuries
- chondromalacia patellae
- osteoarthritis of the knee
- osteochondral defects
- osteochondritis dissecans of the knee
- pattern of bone contusion in knee injuries
- knee fractures
- anterior cruciate ligament tear
- anterior cruciate ligament ganglion cyst
- anterior cruciate ligament mucoid degeneration
- posterior cruciate ligament tear
- medial collateral ligament tear
- lateral collateral ligament tear
- medial patellofemoral ligament tear
- posterolateral corner injury
- posteromedial corner injury
- meniscal lesions
- meniscal tear
- meniscal/parameniscal cyst
- meniscal flounce
- meniscal fraying
- meniscocapsular separation
- bursosynovial lesions
- fat pad
- popliteal fossa