Official reprint from UpToDate®
www.uptodate.com ©2016 UpToDate®

Approach to the child with bow-legs

Scott B Rosenfeld, MD
Section Editors
William Phillips, MD
Jan E Drutz, MD
Deputy Editor
Mary M Torchia, MD


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

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 bow-legs or knock-knees have variations of normal lower-extremity development that 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 bow-legs include Blount disease, nutritional rickets and other metabolic bone diseases, skeletal dysplasia, infection, trauma, and neoplasia. Unlike physiologic bowing, 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 bowing, and an approach to the child with bow-legs. Knock-knees are discussed separately. (See "Approach to the child with knock-knees".)


An understanding of normal development of the lower extremity is essential to differentiation of physiologic from pathologic deformities.


Subscribers log in here

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information or to purchase a personal subscription, click below on the option that best describes you:
Literature review current through: Sep 2016. | This topic last updated: May 11, 2016.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2016 UpToDate, Inc.
  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. Stans AA. Osteomyelitis and septic arthritis. In: Lovell and Winter's Pediatric Orthopaedics, 6th ed, Morrissy RT, Weinstein SL (Eds), Lippincott Williams & Wilkins, Philadelphia 2006.
  4. Cheema JI, Grissom LE, Harcke HT. Radiographic characteristics of lower-extremity bowing in children. Radiographics 2003; 23:871.
  5. Kling TF Jr. Angular deformities of the lower limbs in children. Orthop Clin North Am 1987; 18:513.
  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. Greene WB. Genu varum and genu valgum in children: differential diagnosis and guidelines for evaluation. Compr Ther 1996; 22:22.
  8. Scherl SA. Common lower extremity problems in children. Pediatr Rev 2004; 25:52.
  9. Blount WP. Tibia vara: Osteochondrosis deformans tibiae. J Bone Joint Surg 1937; 19:1.
  10. Bradway JK, Klassen RA, Peterson HA. Blount disease: a review of the English literature. J Pediatr Orthop 1987; 7:472.
  11. Feldman MD, Schoenecker PL. Use of the metaphyseal-diaphyseal angle in the evaluation of bowed legs. J Bone Joint Surg Am 1993; 75:1602.
  12. Bowen RE, Dorey FJ, Moseley CF. Relative tibial and femoral varus as a predictor of progression of varus deformities of the lower limbs in young children. J Pediatr Orthop 2002; 22:105.
  13. Zionts LE, Shean CJ. Brace treatment of early infantile tibia vara. J Pediatr Orthop 1998; 18:102.
  14. Loder RT, Johnston CE 2nd. Infantile tibia vara. J Pediatr Orthop 1987; 7:639.
  15. Bruce RW Jr. Torsional and angular deformities. Pediatr Clin North Am 1996; 43:867.
  16. Loeffler RD Jr, Sherman FC. The effect of treatment on growth and deformity in hypophosphatemic vitamin D-resistant rickets. Clin Orthop Relat Res 1982; :4.
  17. Shirley ED, Ain MC. Achondroplasia: manifestations and treatment. J Am Acad Orthop Surg 2009; 17:231.
  18. Sass P, Hassan G. Lower extremity abnormalities in children. Am Fam Physician 2003; 68:461.
  19. Herring JA. Skeletal Dysplasias. In: Tachjidan's Pediatric Orthopaedics, 4th ed, Saunders, Philadelphia 2008.
  20. Heath CH, Staheli LT. Normal limits of knee angle in white children--genu varum and genu valgum. J Pediatr Orthop 1993; 13:259.
  21. Levine AM, Drennan JC. Physiological bowing and tibia vara. The metaphyseal-diaphyseal angle in the measurement of bowleg deformities. J Bone Joint Surg Am 1982; 64:1158.
  22. McCarthy JJ, Betz RR, Kim A, et al. Early radiographic differentiation of infantile tibia vara from physiologic bowing using the femoral-tibial ratio. J Pediatr Orthop 2001; 21:545.
  23. Greene WB. Genu varum and genu valgum in children. Instr Course Lect 1994; 43:151.
  24. Driano AN, Staheli L, Staheli LT. Psychosocial development and corrective shoewear use in childhood. J Pediatr Orthop 1998; 18:346.
  25. Goldman V, Green DW. Advances in growth plate modulation for lower extremity malalignment (knock knees and bow legs). Curr Opin Pediatr 2010; 22:47.