Subluxation of the Patella
Subluxation or dislocation of the patella is a rare phenomenon seen in two distinct settings in the pediatric age group. The first is congenital dislocation of the patella, often accompanying frank dislocation of the knee. Drennan gives an overview of this rare anomaly, which occurs in about 1 in 1000 births (or 1% of the frequency of hip dysplasia). It commonly is associated with neuromuscular syndromes such as myelodyplasia and arthrogryposis, or genetic syndromes, including Down, Larsen, Ehler-Danlos, and Turner syndromes. Isolated congenital dislocation of the patella is found most commonly in patients who have the nail-patella syndrome, an autosomal dominant disorder that involves hypoplastic nails and patellae.
