Study Guide

Congenital Knee Dislocation

Key Points:

Description:

Congenital knee dislocation (CKD) is a rare condition that involves hyperextension of the knee joint with varying degrees of anterior tibia displacement diagnosed at birth.  The most common classification used defines simple hyperextension (Grade 1), anterior tibial subluxation reducible with flexion (Grade 2), and true anterior tibial dislocation (Grade 3). (Curtis, 1969; Neibauer, 1960)

Epidemiology:

CKD incidence has been reported at 1 in 100,000 live births, or, to better conceptualize its rarity, 1% of the incidence of congenital hip dislocation. (Drennan, 1993; Jacobsen, 1985)

Clinical Findings:

Congenitally dislocated knees have hyperextension contractures with transverse anterior skin folds due to a shortened, sometimes fibrotic quadriceps, tight anterior capsule, and hypoplastic suprapatellar bursa. (Curtis, 1969; Neibauer, 1960; Baldwin, 1926; Ooishi, 1993)   The tibia may have rotatory or valgus deformity, the hamstrings may displace anteriorly and act as extensors, and there may be general laxity from cruciate pathology or displaced collateral ligaments. (Neibauer, 1960; Jacobsen, 1985; Laurence, 1967) Deformity and knee hyperextension can be so severe that the infant’s resting position is with the feet adjacent to the head.  Breech presentation in seen in up to 30%, clubfoot in up to 47%, and hip dislocations in up to 50%. (Curtis, 1969; Neibauer, 1960; Johnson, 1987; Ko, 1999)  CKD has also been commonly associated with arthrogryposis, myelodysplasia, or syndromes such as Larsen, Ehlers-Danlos, or Beals syndrome.  Absence of these syndromes and associated deformities, initial range of motion, and time to treatment are the best prognostic indicators. (Curtis, 1969; Laurence, 1967; Johnson, 1987; Shah 2009)

Imaging Studies:

Prenatal ultrasound may identify CKD. (Monteagudo, 2006) There have been rare cases of intrauterine diagnosis from maternal abdominal radiographs. (Lage, 1986; Elchalal, 1993) The diagnosis of CKD is primarily clinical and radiographs are used as a confirmatory study.  Radiographs confirm contact between the femoral and tibial epiphysis in Grade 1 and 2 CKD, whereas in Grade 3 CKD the epiphyses are not in contact and the tibia is anterior to the femur. There may be a role for arthrography in knees that fail conservative treatment to better understand the pathologic anatomy prior to surgical intervention, but some dispute its usefulness in guiding management. (Curtis, 1969; Ooishi, 1993; Ko, 1999; Haga, 1997)

Treatment:

Most Grade 1 and 2 CKD can be treated non-operatively, with serial casting with or without supplemental skin traction. (Curtis, 1969; Neibauer, 1960; Johnson, 1987; Ko, 1999) Treatment is best when applied as soon as possible, with some advocating initiating treatment less than 20 hours after birth. (Ko, 1999) Once 90 degrees of knee flexion has been achieved, a splint or Pavlik harness can be utilized to maintain correction until the tendency for recurrence has passed. In the presence of a more severe quadriceps contracture, a botulinum toxin injection may assist with progressive stretching and knee flexion. (Kaissi, 2011)   

If casting fails, surgery has traditionally consisted of quadriceps lengthening; hamstring, IT band, and capsular release; possible ACL advancement. (Curtis, 1969; Neibauer, 1960; Ooishi, 1993; Johnson, 1987; Ko, 1999) Recent studies, pointing to long term quadriceps insufficiency with this approach, advocate instead for femoral shortening osteotomy to produce relative lengthening of the quadriceps mechanism. (Johnston, 2011; Sud, 2009; Oetgen, 2010) Posterolateral and posteromedial capsulorraphies after excision of redundant posterior capsule may reduce laxity of the knee and the tendency for subluxation.  Anterior cruciate reconstruction can be considered if there is excessive anterior laxity at the time of open reduction.

Minimally invasive treatment of CKD has been reported with mini-open and percutaneous quadricepsplasty. (Abdelaziz, 2011; Shah, 2009)

Treatment of CKD prior to treating concomitant hip or foot pathology has been a common practice guideline, but at least one recent study endorses simultaneous treatment of hip and knee dislocation using dual open reductions and femoral shortening osteotomy. (Ooishi, 1993; Johnston, 2011)  Clubfoot casting may also be carried out simultaneously with casting for CKD. (Shah 2009)

Complications:

In general, CKD treated both operatively and non-operatively have favorable functional results. (Oetgen, 2010) Closed reduction attempts without first applying traction to clear the tibia distally from the femur has led to epiphyseal deformity. (Laurence, 1967) Residual hyperextension may persist in those casted, and laxity or valgus deformity is found in some post-operatively. (Laurence, 1967; Curtis, 1969) Quadriceps insufficiency has been associated with open reduction and quadriceps lengthening. (Oetgen, 2010)

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References:

  1. Abdelaziz TH, Samir S: Congenital dislocation of the knee: A protocol for management based on degree of knee flexion. J Child Orthop 2011; 5(2):143-149.
  2. Baldwin CH.  Congenital dislocation of the knee joint.  J Bone Joint Surg Am.  1926 Oct; 8(4): 822-823.
  3. Curtis BH, Fisher RL.  Congenital hyperextension with anterior subluxation of the knee.  J Bone Joint Surg Am.  1969 Mar; 51(2): 255-269.
  4. Drennan JC. Congenital dislocation of the knee and patella. Instr Course Lect. 1993; 42:517–524.
  5. Elchalal U, et al.  Antenatal diagnosis of congenital dislocation of the knee: a case report.  Am J Perinatal.  1993 May; 10(3): 194-6.
  6. Ferris B, Aichroth P.  The treatment of congenital knee dislocation: a review of nineteen knees.  Clin Orth Rel Res.  1987 Mar; 216:135-140.
  7. Haga N, et al.  Congenital dislocation of the knee reduced spontaneously or with minimal treatment.  J Pediatr Orthop.  1997 Jan; 17(1): 59-62.
  8. Jacobsen K, Vopalecky F.  Congenital dislocation of the knee.  Acta Orthop Scand.  1985 Feb; 56(1): 1-7.
  9. Johnson E, Audell R, Oppenheim WL.  Congenital dislocation of the knee.  J Pediatr Orthop.  1987 May-Apr; 7(2): 194-200.
  10. Johnston CE.  Simultaneous open reduction of ipsilateral congenital dislocation of the hip and knee assisted by femoral diaphyseal shortening.  J Pediatr Orthop.  2011 Oct; 31(7): 732-40.
  11. Kaissi AA, Ganger R, Klaushofer K, Grill F: The management of knee dislocation in a child with Larsen syndrome. Clinics (Sao Paulo) 2011; 66(7):1295-1299.
  12. Ko JY, Shih CH, Wenger DR.  Congenital dislocation of the knee.  J Pediatr Orthop.  1999 March; 19(2): 252-259.
  13. Lage J, et al.  Intrauterine diagnosis of dislocation of the knee.  J Pediatr Orthop.  1986 Jan-Feb; 6(1): 110-1.
  14. Laurence M.  Genu recurvatum congenitum.  J Bone Joint Surg Br.  1967 Feb; 49(1): 121-34.
  15. Monteagudo A, Kudla MM, Essig M, Santos R, Timor-Tritsch IE: Real-time and 3-dimensional sonographic diagnosis of postural congenital genu recurvatum. J Ultrasound Med 2006; 25(8):1079-1083.
  16. Neibauer JJ, King DE.  Congenital dislocation of the knee.  J Bone Joint Surg Am.  1960 Mar; 42-A: 207-25.
  17. Oetgen ME, et al.  Functional results after surgical treatment for congenital knee dislocation.  J Pediatr Orthop.  2010 April; 30(3): 216-223.
  18. Ooishi T, et al.  Congenital dislocation of the knee.  Its pathologic features and treatment.  Clin Orthop Relat Res.  1993 Feb; (287): 187-92.
  19. Shah NR, Limpaphayom N, Dobbs MB: A minimally invasive treatment protocol for the congenital dislocation of the knee. J Pediatr Orthop 2009; 29(7):720-725.
  20. Sud A, et al.  Functional outcome following quadriceps tendon lengthening in congenital dislocation of the knee, with special reference to extensor weakness.  Strategies Trauma Limb Reconstr.  2009 Dec; 4(3): 123-7.

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Jennifer Bauer MD
Jeff Martus MD