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Congenital Dislocation of the Patella

What is congenital dislocation of the patella?

Congenital dislocation of the patella is a rare condition where the kneecap (or patella) is out of place at the knee joint. This is usually discovered at birth. The patella is positioned to the side of the knee instead of the front of the knee. This is different from adolescents or older children who may have episodes where their kneecap moves out of place with sports or activities because of laxity (looseness) or injury. Congenital dislocation of the patella may be seen in association with other lower extremity deformities where the knee is stuck in a bent position (flexion contracture) and with lower leg and/or foot deformities. It may be associated with Down syndrome, nail-patella syndrome, Larsen syndrome, Rubinstein-Taybi syndrome, arthrogryposis, Ellis-van Creveld syndrome and diastrophic dysplasia.

The muscles on top of the thigh, (quadriceps muscles) may be tight or shortened. The child may be delayed in walking or present with a knock-knee appearance. The kneecap may be small and can be felt or seen over the outer aspect of the knee. It is not located on the front part of the knee as normal because of bony deformity and/or tight tissues/muscles that pull the patella over to the side.

The groove or area where the patella travels up and down over the front of the knee with motion is called the trochlea; this may be shallow or under-developed. Special imaging such as an MRI or ultrasound may need to be performed to identify the patella and its location about the knee and for possible planning for intervention. Children with congenital dislocation of the patella typically cannot straighten their knee actively, though passively they can get their knees straight.

How is congenital dislocation of the patella treated?

Patients with congenital dislocation of the patella may fall frequently and have abnormal gaits. Surgical treatment may be considered or necessary if there is difficulty with mobility and/or function secondary to congenital dislocation of the patella. This is called a realignment or centralization procedure of the patella. This may consist of lengthening the tissues/muscles on the top and outside aspect of the thigh (lateral release and/or V-Y quadricepsplasty). In some cases, it is necessary to also shorten the thigh bone (femoral shortening osteotomy). If surgery is recommended in bilateral cases, we typically do one side, allow it to fully heal, and then do the second side. Physical therapy rehabilitation is needed to achieve maximum outcomes. Successful treatment restores a more normal mechanical alignment and, in turn, better ambulation and function.

What are the risks of surgical treatment?

Surgical intervention has the potential for improved alignment, walking, mobility and function, but carries some risks. Complications from surgery can occur such as blood loss, infection at the operative site, injuries of nerve and blood vessels, loss of motion in the joints, difficulty healing, blood clots, problems with hardware used for fixation, recurrence of patellar instability or deformity and need for other procedures to help with healing and correction.

Why come to the International Center for Limb Lengthening for treatment of congenital dislocation of the patella?

Limb Lengthening and deformity correction are complex processes. Your doctor at the International Center for Limb Lengthening will take the time to make sure you understand all of your options and then will customize your treatment to meet your specific needs. Our patients benefit from our team-centered approach with world-renowned surgeons and specialized physician assistants, nurses and physical therapists. We help patients with congenital dislocation of the patella achieve their best possible result.

Doctors Who Treat Congenital Dislocation of the Patella