Congenital dislocation/subluxation of knee
Objectives- Describe synonyms or gradations of severity of congenital dislocation/subluxation of knee.
- Describe treatment for the least rigid form (physiologic genu recurvatum) of congenital hyperextension of the knee
- Describe the pathology of the more rigid forms of congenital dislocation/subluxation of the knee
- List other conditions commonly associated with congenital dislocation/subluxation of the knee
Discussion points
- Describe the exam of the newborn with hyperextended knees. What are the critical factors for prognosis?
- How can the fixed dislocation be treated? At what age should surgery be done, if indicated?
- If both knees and hips are dislocated, which joint is better treated first?
Discussion
Several terms are often used in describing congenital hyperextension of the knee, a descriptive term indicating recurvatum of the knees at birth. At least half of all babies presenting with this clinical appearance will have some passive flexion at birth and can be managed with casting and/or Pavlik harness to maintain knee flexion for a few weeks. Fixed subluxation/dislocation is more difficult and often accompanies fixed dislocation of the hips in the neonate. Treatment is difficult for congenital dislocation of the knee and/or hip associated with Larsen's syndrome or amyoplasia. Fibrosis of the quadriceps associated with this type of congenital dislocation of the knee is present from early embryonic life; it is these changes that separate the structural, difficult congenital knee dislocations from the more easily treatable postural deformations. Reduction of congenital dislocation of the knee should be accomplished in infancy. For dislocations associated with quadriceps fibrosis, surgical lengthening of the extensor mechanism is the first step, after which the knees can be flexed and reduced. Longterm outlook is variable but lack of complete flexion is common. When congenital dislocation of both hip and knee are present, the knee must be treated first. Cruciate deficiency does not accompany this disorder.
References
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May 16-19, 2012 in Denver, CO
