Patella baja

Last revised by Dr Tee Yu Jin on 06 Apr 2020

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

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

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

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.

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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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  • Case 2
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