Congenital Dislocations: Knee and Patella

Abstract

Congenital dislocation of the knee is a rare condition. It is apparent at birth, and infants usually present with a dramatic hyperextension deformity. Treatment with serial casting should begin as soon as possible in infancy. In knees with more severe quadriceps contractures that prevent effective gradual flexion, a femoral nerve block or botulinum toxin can be a helpful adjunct. A trial of nonsurgical management is appropriate until 12 months of age. Surgical management, including lengthening of the quadriceps mechanism via either V-Y quadricepsplasty or a relative lengthening via an acute femoral shortening (2-3 cm), is indicated in patients who do not respond to casting. Mini-open and percutaneous quadricepsplasty also have been described with good short-term results. Congenital patellar dislocation is a laterally displaced, hypoplastic patella with severe trochlear dysplasia or an absent trochlea. This condition is often present at birth, but a diagnosis may not be made until years later. If the child has progressive functional decline or developmental milestones are not achieved, surgical treatment should be considered. Extensive lateral release with release of the iliotibial band and occasionally the biceps femoris should be performed. If this release does not allow for centralization of the patella and extensor mechanism, then a V-Y quadricepsplasty or acute femoral shortening should be performed. After centralization, medial imbrication is necessary to maintain reduction.

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