Patella baja

Patella baja (or patella infera) is an abnormally low lying patella, which is associated with restricted range of motion, crepitations, and retropatellar pain. If longstanding, extensor dysfunction may ensue with significant morbidity.  It is seen in a variety of clinical scenarios including 1:

  • quadriceps dysfunction:
    • poliomyelitis
    • tourniquet paralysis
  • bony or ligamentous trauma:
    • fractures
    • osteotomies
    • tibial tubercle transplant
    • ACL repair
    • total knee replacement: seen in 25% of patients 1

Radiographic features

A number of methods for determining patella height have been devised:

  • Insall-Salvati ratio: according to the relative height of the patella and length of the patellar tendon. It is assessed on lateral radiographs or sagittal cross-sectional imaging. 
  • Blackburne-Peel ratio: ratio of vertical distance between tibial plateau and patellar articular surface and length of the patellar articular surface.
  • Norman, Egund and Ekelund method
  • Caton-Linclau method
  • Blumensaat technique

It is important in the setting of previous surgery to ensure that the patella has not been resected, as change in patellar morphology will clearly affect the ratio 1.

Treatment and prognosis

Traumatic/post-surgical patella baja is frequently symptomatic and requires early surgical correction as conservative measures are rarely successful. Treatment requires either a tibial tuberosity osteotomy and re-implantation proximally or patellar tendon lengthening.

Knee pathology

The knee is a complex synovial joint that can be affected by a range of pathologies:

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Article information

rID: 7498
Section: Gamuts
Tag: knee
Synonyms or Alternate Spellings:
  • Patella infera
  • Low lying patella

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Cases and figures

  • Fig 1: normal patella: sag T2 FS
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  • Case 1: with concurrent lateral tilt
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  • Low riding of the...
    Case 2
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