This image is of an extreme case of patella baja (one of our knee forum patients!) where the tissues below the patella repeatedly became 'stuck down', eventually requiring radical surgery of cutting the patellar tendon, mobilising the knee until it was quiet, and then grafting the tendon.
Who gets patella baja?
Some people are born with an atypically low patella, but more often it is a complication of injury or surgery. An abnormally low patella (also called patella infera) is a common complication of total knee replacement. It can also occur after quadriceps muscle weakness, opening-wedge tibial osteotomy, fractures of the tibia, and arthrofibrosis inside the knee.
Consequences of patella baja
If patella baja is not adequately managed it can lead to decreased range of motion (ROM), inability to fully straighten the knee, impingement with anterior knee pain and possibly rupture of the patellar tendon.
Patella baja and total knee arthroplasty (TKA): etiology, diagnosis, and management. Chonko DJ, Lombardi AV Jr. and Berend KR. Surg Technol Int. 2004;12:231-8.
Complete excision of the infrapatellar fat pad is associated with patellar tendon shortening after primary total knee arthroplasty. Gwyn R, Kotwal RS, Holt MD, Davies AP. Eur J Orthop Surg Traumatol. 2016 Jul;26(5):545-9.
Changes in patella tendon length over 5 years after different types of knee arthroplasty. Davies GS, et al. Knee Surg Sports Traumatol Arthrosc. 2016 Sep;24(9):3029-35.
Patellar tendon lengthening for patella infera using the Ilizarov technique. In Y, Kim SJ, Kwon YJ. J Bone Joint Surg Br. 2007 Mar;89(3):398-400.
Kindle eBook - Authors: Frank Noyes & Sue Barber-Westin
Knee Arthrofibrosis: Everything You Need to Know to Recognize, Treat, and Prevent Loss of Knee Motion After Injury or Surgery