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genu recurvatum

Genu recurvatum

Genu recurvatum also known as hyperextension of the knee or back knee, is defined as the backward curvature of the knee. In genu recurvatum, excessive extension occurs in the tibiofemoral joint. Genu recurvatum deformity is more common in women 1 and people with familial ligamentous laxity 2. Hyperextension of the knee may be mild, moderate or severe. A range of 0° to 5° of genu recurvatum has been suggested as normal 3. Studies that report normal values by sex are limited and provide a wide range with mean values between 0.2° and 5.8° in females and between –0.3° and 3.2° in males 4. As with many of the other alignment variables, the reasons for a sex difference in genu recurvatum are unknown 1. In-creased laxity of the anterior cruciate ligament (ACL) has been suggested to contribute to hyperextension at the knee 5, because the ACL is taut when the knee is in full extension 6. Greater anterior laxity of the knee, a motion largely restricted by the ACL, has been reported in females compared to males 7 and could potentially lead to greater genu recurvatum in females. In addition, general joint laxity has been shown to be greater in females than males, of which genu recurvatum of greater than 10° is one of the criteria 4. Another possible explanation for the sex difference found in genu recurvatum may be a relationship to the increased anterior pelvic tilt observed in females. An excessive anterior pelvic tilt has been suggested to create a flexion moment at the hip that is counteracted with an extension moment at the knee, resulting in hyperextension at the knee joint 8.

The most important factors of knee stability include:

  • Ligaments of the knee: The knee joint is stabilized by four main ligaments:
    • Anterior cruciate ligament (ACL). The ACL has an important role in stabilization of knee extension movement by preventing the knee from hyperextending.
    • Posterior cruciate ligament (PCL)
    • Medial collateral ligament (MCL)
    • Lateral collateral ligament (LCL)
  • Joint capsule or articular capsule (especially posterior knee capsule)
  • Quadriceps femoris muscle
  • Appropriate alignment of the femur and tibia (especially in knee extension position )

Genu recurvatum causes

The following factors may be involved in causing genu recurvatum:

  • Inherent laxity of the knee ligaments
  • Weakness of biceps femoris muscle
  • Instability of the knee joint due to ligaments and joint capsule injuries
  • Inappropriate alignment of the tibia and femur
  • Malunion of the bones around the knee
  • Weakness in the hip extensor muscles
  • Gastrocnemius muscle weakness (in standing position)
  • Upper motor neuron lesion (for example, hemiplegia as the result of a cerebrovascular accident)
  • Lower motor neuron lesion (for example, in post-polio syndrome)
  • Deficit in joint proprioception
  • Lower limb length discrepancy
  • Congenital genu recurvatum
  • Cerebral palsy
  • Muscular dystrophy
  • Limited dorsiflexion (plantar flexion contracture)
  • Popliteus muscle weakness
  • Connective tissue disorders. In these disorders, there are excessive joint mobility (joint hypermobility) problems. These disorders include:
    • Marfan syndrome
    • Loeys-Dietz syndrome
    • Ehlers-Danlos syndrome
    • Benign hypermobile joint syndrome
    • Osteogenesis imperfecta disease

Genu recurvatum treatment

Genu recurvatum treatment involves treating the underlying cause.

Treatment generally includes the following:

  • Sometimes pharmacologic therapy for initial disease treatment
  • Physical therapy
  • Occupational therapy
  • Use of appropriate assistive devices such as orthoses
  • Surgical treatment

Congenital genu recurvatum

Congenital genu recurvatum also called congenital dislocation of the knee, is an extremely rare condition observed at birth with an incidence rate of about 1 per 70,000 – 100,000 live births 9. Congenital genu recurvatum is defined as a pathological hyperextension of the knee greater than 30°, associated with marked restriction of flexion 9. Congenital genu recurvatum is more common in females 10. The degree of genu recurvatum is not in itself correlated with prognosis 11, but rather this depends on the presence or not of a dislocation of the knee 12.

Congenital genu recurvatum can be divided in two groups 13:

  1. Malformative congenital genu recurvatum involving anomalies of the elastic tissues. Malformative congenital genu recurvatum is mostly associated with Larsen syndrome, a recessive or autosomal disorder (locus 3p21.1‐p14.1) with high clinical variability. In this syndrome, congenital genu recurvatum tends to be bilateral and other structural abnormalities are generally present such as flat face with hypertelorism, accessory carpal bones and short terminal phalanges creating pseudoclubbing 14. The prenatal diagnosis of Larsen syndrome has been recently reported in a severely affected fetus 15. Other genetic disorders associated with congenital genu recurvatum such as partial trisomy 1q and monosomy 6p have been reported in the literature 16.
  2. Postural congenital genu recurvatum as a consequence of abnormal presentation or oligohydramnios. Oligohydramnios and/or footling presentation are mainly responsible for postural congenital genu recurvatum. Possible etiological factors for this condition include shortening of the quadriceps secondary to fibrosis of ischemic origin 17. Women undergoing amniocentesis at 11 + 5 to 14 + 6 weeks’ gestation have an increased risk of giving birth to a child with congenital foot deformity 18, and this increased risk may be limited to amniocenteses performed before the 13th week of gestation 19.

Congenital genu recurvatum can either be isolated, associated with among other malformations such as developmental dysplasia of the hip and clubfoot, or part of a syndrome such as the Larsen syndrome or it may occur in paralytic conditions such as meningomyelocele. Other conditions, especially when complete dislocation of the knee is observed, must be looked for even if they remain exceptional, and amniocentesis for fetal karyotyping should be performed to rule out Down and Turner syndromes 20.

Congenital genu recurvatum cause knee instability, pain and be associated with shortening of the limbs 21.

When congenital genu recurvatum is isolated, orthopedic treatment will usually lead to a good functional prognosis 9.

Figure 1. Congenital genu recurvatum

Footnote: Left knee joint genu recurvatum. Note the angulation of knee joint in comparison to right knee joint.

[Source 22 ]

Congenital genu recurvatum treatment

Treatment of isolated congenital genu recurvatum includes orthopedic physiotherapy and progressive reduction of the hyperextension by means of serial splinting, which allows early recovery of knee mobility. However, when congenital genu recurvatum is associated with dislocation of the knee, surgery is required which usually results in complete recovery of joint mobility 23.

References
  1. Sex differences in clinical measures of lower extremity alignment. J Orthop Sports Phys Ther. 2007 Jul;37(7):389-98. DOI:10.2519/jospt.2007.2487 https://www.jospt.org/doi/pdf/10.2519/jospt.2007.2487
  2. Benson, Michael; Fixsen, John; Macnicol, Malcolm (1 August 2009). Children’s Orthopaedics and Fractures. Springer. pp. 495–. ISBN 978-1-84882-610-6.
  3. Loudon JK, Jenkins W, Loudon KL. The relationship between static posture and ACL injury in female athletes. J Orthop Sports Phys Ther. 1996;24:91-97.
  4. Scerpella TA, Stayer TJ, Makhuli BZ. Ligamentous laxity and non-contact anterior cruciate ligament tears: a gender-based comparison. Orthopedics. 2005;28:656-660.
  5. Noyes FR, Dunworth LA, Andriacchi TP, Andrews M, Hewett TE. Knee hyperextension gait abnormalities in unstable knees. Recognition and preoperative gait retraining. Am J Sports Med. 1996;24:35-45.
  6. Norkin CC, Levangie PK. Joint Structure and Function: A Comprehensive Analysis. Philadelphia, PA: F.A. Davis Co; 1992.
  7. Shultz SJ, Sander TC, Kirk SE, Perrin DH. Sex differences in knee joint laxity change across the female menstrual cycle. J Sports Med Phys Fitness. 2005;45:594-603.
  8. Kendall FP, McCreary EK, Provance PG. Muscles Testing and Function. Philadelphia, PA: Lippincott Williams & Wilkins; 1993.
  9. Gorincour, G. , Chotel, F. , Rudigoz, R. C., Guibal‐Baggio, A. L., Berard, J. , Pracros, J. P. and Guibaud, L. (2003), Prenatal diagnosis of congenital genu recurvatum following amniocentesis complicated by leakage. Ultrasound Obstet Gynecol, 22: 643-645. doi:10.1002/uog.884
  10. Fernandez PF and Silva JR. Congenital dislocation of the knee. Int Orthop 1990; 14:17-19.
  11. Laurence M. Genu‐recurvatum congenitum. J Bone Joint Surg 1967; 49B: 121–134.
  12. Seringe R, Renaud I. Congenital dislocation of the knee in the newborn. Paper presented at the 49th Congress of Pediatric Surgery, Paris, France, 1992.
  13. Nie Bauer JJ, King DE. Congenital dislocation of the knee. J Bone Joint Surg 1960; 50A: 207–225.
  14. Harris R, Cullen CH. Autosomal dominant inheritance in Larsen syndrome. Clin Genet 1971; 2: 87–90.
  15. Becker R, Wegner RD, Kunze J, Runkel S, Vogel M, Entezami M. Clinical variability of Larsen syndrome. Clin Genet 2000; 57: 148–150.
  16. Pierquin G, Van Regemorter N, Hayez‐Delatte, Fourneau C, Foerster M, Damis E, Cremer‐Perlmutter N, Lapiere CM, Vamos E. Two unrelated children with partial trisomy 1q and monosomy 6p, presenting with the phenotype of Larsen syndrome. Hum Genet 1991; 87: 587–591.
  17. Ferris B, AichRoth P. The treatment of congenital knee dislocation. A review of nineteen knees. Clin Orthop 1987; 216: 135–140.
  18. Nikkila A, Valentin L, Thelin A, Jorgensen C. Early amniocentesis and congenital foot deformities. Fetal Diagn Ther 2002; 17: 129–132.
  19. Yoon C, Chernos J, Sibbald B, Lowry B, Connors G, Simrose R. Association between congenital foot anomalies and gestational age at amniocentesis. Prenat Diagn 2001; 21: 1137–1141.
  20. Johnson E, Audell R, Oppenheim W. Congenital dislocation of the knee. J Pediatr Orthop 1987; 7: 194–200.
  21. A. M. Pappas, P. Anas and H. M. Toczylowski Jr., “Asymmetrical Arrest of the Proximal Tibial Physis and Genu Recurvatum Deformity,” J Bone Joint Surg 1984;66:575-81
  22. Sharma, D., Yadav, J., Garg, E., & Bajaj, H. (2014). Congenital Genu Recurvatum. https://pdfs.semanticscholar.org/a1f4/ea08eeccf79ac84d5e1bf103c41b334a46a8.pdf
  23. Bensahel H, Dalonte A, Hjelmstedt A. Congenital dislocation of the knee. J Pediatr Orthop 1989; 9: 174–177.
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