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Approach to the child with knock-knees

Author
Scott B Rosenfeld, MD
Section Editors
William Phillips, MD
Teresa K Duryea, MD
Deputy Editor
Mary M Torchia, MD

INTRODUCTION

Knock-knees (genu valgum) is an angular deformity at the knee where the apex of the deformity points toward the midline (figure 1). Bow-legs (genu varum) is an angular deformity at the knee where the apex of the deformity points away from the midline.

Bow-legs and knock-knees are among the most common musculoskeletal anatomic variations encountered by pediatric primary care providers and a common reason for referral to a pediatric orthopedic surgeon. However, most children with knock-knees or bow-legs have variations of normal lower-extremity development and can be monitored by the primary care provider.

An understanding of the normal physiologic development of the lower extremity is essential in differentiating physiologic from pathologic alignment. Pathologic causes of knock-knees include posttraumatic (eg, Cozen fracture), rickets (eg, renal osteodystrophy), skeletal dysplasias, mucopolysaccharidosis, and neoplasms. Unlike physiologic knock-knees, these conditions generally do not improve over time and may require treatment with bracing or surgery.

This topic will provide an overview of normal physiologic alignment of the lower extremity, physiologic and pathologic causes of knock-knees, and an approach to the child with knock knees. Bow-legs are discussed separately. (See "Approach to the child with bow-legs".)

NORMAL PHYSIOLOGIC ALIGNMENT

An understanding of normal physiologic development of the lower extremity is essential to differentiation of physiologic from pathologic deformities. Lower-extremity alignment goes through a predictable progression from varus (bow-legs) to valgus (knock-knees) over the first seven years of life (figure 2 and figure 3) [1]. There is a wide range of normal values [1,2].

                 

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Literature review current through: Nov 2016. | This topic last updated: Tue Jun 02 00:00:00 GMT+00:00 2015.
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References
Top
  1. Salenius P, Vankka E. The development of the tibiofemoral angle in children. J Bone Joint Surg Am 1975; 57:259.
  2. Shoenecker PL, Rich MM. The Lower Extremity. In: Lovell and Winter's Pediatric Orthopaedics, 6th ed, Morrissy RT, Weinstein SL (Eds), Lippincott Williams & Wilkins, Philadelphia 2006. p.1158.
  3. White GR, Mencio GA. Genu Valgum in Children: Diagnostic and Therapeutic Alternatives. J Am Acad Orthop Surg 1995; 3:275.
  4. Kling TF Jr. Angular deformities of the lower limbs in children. Orthop Clin North Am 1987; 18:513.
  5. Greene WB. Genu varum and genu valgum in children: differential diagnosis and guidelines for evaluation. Compr Ther 1996; 22:22.
  6. The knee and leg. In: Clinical Pediatric Orthopedics The Art of Diagnosis and Principles of Management, Tachdjian MO (Ed), Appleton & Lange, Stamford, CT 1997. p.87.
  7. Sass P, Hassan G. Lower extremity abnormalities in children. Am Fam Physician 2003; 68:461.
  8. Scherl SA. Common lower extremity problems in children. Pediatr Rev 2004; 25:52.
  9. Bruce RW Jr. Torsional and angular deformities. Pediatr Clin North Am 1996; 43:867.
  10. Ogden JA, Ogden DA, Pugh L, et al. Tibia valga after proximal metaphyseal fractures in childhood: a normal biologic response. J Pediatr Orthop 1995; 15:489.
  11. Cozen L. Knock-knee deformity in children. Congenital and acquired. Clin Orthop Relat Res 1990; :191.
  12. Jackson DW, Cozen L. Genu valgum as a complication of proximal tibial metaphyseal fractures in children. J Bone Joint Surg Am 1971; 53:1571.
  13. Barrett IR, Papadimitriou DG. Skeletal disorders in children with renal failure. J Pediatr Orthop 1996; 16:264.
  14. Odunusi E, Peters C, Krivit W, Ogilvie J. Genu valgum deformity in Hurler syndrome after hematopoietic stem cell transplantation: correction by surgical intervention. J Pediatr Orthop 1999; 19:270.
  15. Herring JA. Skeletal Dysplasias. In: Tachjidan's Pediatric Orthopaedics, 4th ed, Saunders, Philadelphia 2008.
  16. Heath CH, Staheli LT. Normal limits of knee angle in white children--genu varum and genu valgum. J Pediatr Orthop 1993; 13:259.
  17. Stieber JR, Dormans JP. Manifestations of hereditary multiple exostoses. J Am Acad Orthop Surg 2005; 13:110.
  18. Greene WB. Genu varum and genu valgum in children. Instr Course Lect 1994; 43:151.
  19. Driano AN, Staheli L, Staheli LT. Psychosocial development and corrective shoewear use in childhood. J Pediatr Orthop 1998; 18:346.
  20. Stevens PM, Maguire M, Dales MD, Robins AJ. Physeal stapling for idiopathic genu valgum. J Pediatr Orthop 1999; 19:645.
  21. Tuten HR, Keeler KA, Gabos PG, et al. Posttraumatic tibia valga in children. A long-term follow-up note. J Bone Joint Surg Am 1999; 81:799.
  22. Stevens PM, Pease F. Hemiepiphysiodesis for posttraumatic tibial valgus. J Pediatr Orthop 2006; 26:385.
  23. Goldman V, Green DW. Advances in growth plate modulation for lower extremity malalignment (knock knees and bow legs). Curr Opin Pediatr 2010; 22:47.