Blackburne-Peel ratio
The Blackburne-Peel ratio is an alternative to Insall-Salvati ratio and is used to assess patellar height including patella alta and baja.
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Usage
The Blackburne-Peel ratio has higher interobserver reliability compared to the Insall-Salvati ratio and can also be used when the tibial tuberosity is abnormal (e.g. Osgood-Schlatter disease, osteotomy) as it does not rely on this landmark 3,4.
Measurement
A lateral radiograph of the knee with 30° of flexion is obtained, and a horizontal line at the level of the tibial plateau is drawn. Perpendicular to this line (i.e. vertically) two measurements are made:
- A: along the patellar articular surface
- B: distance between the horizontal line and the inferior aspect of the patellar articular surface
B/A is a measure of patellar height
Interpretation
- patella baja: <0.5
- normal: 0.8
- patella alta: >1.0
Related Radiopaedia articles
Knee pathology
The knee is a complex synovial joint that can be affected by a range of pathologies:
- bone and cartilage
-
knee fractures
- distal femoral condyle fracture
- tibial plateau fracture (classification)
- patella fracture
-
avulsion fractures of the knee
- arcuate complex avulsion fracture (arcuate sign)
- anterior cruciate ligament avulsion fracture
- biceps femoris avulsion fracture
- iliotibial band avulsion fracture
- patella fracture
- posterior cruciate ligament avulsion fracture
- reverse Segond fracture
- Segond fracture
- semimembranosus tendon avulsion fracture
- Stieda fracturechronic avulsion injuries
- dislocation
- chondromalacia patellae
- osteoarthritis of the knee
- osteochondral defects
- osteochondritis dissecans of the knee
- patterns of bone bruise in knee injury
-
knee fractures
- ligaments
- 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
- tendons
- meniscal lesions
- bursosynovial lesions
- fat pad
- popliteal fossa
- fascia
- alignment
- knee
- patellofemoral
- gamut