low lying patella
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.
Pathology
It is seen in a variety of clinical scenarios including :
- quadriceps dysfunction:
- poliomyelitis
- tourniquet paralysis
- bony or ligamentous trauma:
- fractures
- osteotomies
- tibial tubercle transplant
- ACL repair
- total knee replacement: seen in 25% of patients
- achondroplasia: usually asymptomatic
Radiographic features
A number of methods for determining patella height have been devised:
- Insall-Salvati ratio
- Blackburne-Peel ratio
- 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 a change in patellar morphology will clearly affect the ratio .
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.
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Assoziationen und Differentialdiagnosen zu Patella baja:
