Citation, DOI & article data
Patella baja, also known as 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:
- tourniquet paralysis
- bony or ligamentous trauma:
- tibial tubercle transplant
- ACL repair
- total knee replacement: seen in 25% of patients 1
- achondroplasia: usually asymptomatic
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 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.
- 1. Weale AE, Murray DW, Newman JH et-al. The length of the patellar tendon after unicompartmental and total knee replacement. J Bone Joint Surg Br. 1999;81 (5): 790-5. J Bone Joint Surg Br (link) - Pubmed citation
- 2. In Y., S.-J. Kim and Y.-J. Kwon. “Patellar tendon lengthening for patella infera using the Ilizarov technique.” J Bone Joint Surg Br 89-B, no. 3 (March 1, 2007): 398-400. doi:10.1302/0301-620X.89B3.18586.
- 3. Upadhyay S, Raza HK, Srivastava P. Position of the patella in adults in central India: evaluation of the Insall-Salvati ratio. J Orthop Surg (Hong Kong). 2013;21 (1): 23-7. Pubmed citation