eMedicine Specialties > Orthopedic Surgery > Knee

Blount Disease: Workup

Author: Matthew J DeOrio, MD, Staff Physician, Department of Orthopedic Surgery, Mayo Clinic of Rochester
Coauthor(s): James K DeOrio, MD, Director of Foot and Ankle Fellowship Program, Assistant Professor of Orthopedic Surgery, Orthopedic Surgery, St Lukes Hospital, Jacksonville, Florida
Contributor Information and Disclosures

Updated: Nov 18, 2008

Workup

Laboratory Studies

  • Lab studies have not been shown to aid in the diagnosis of Blount disease. The diagnosis of both forms of Blount disease is based on history, physical examination, and, most important, radiographs of the knee.

Imaging Studies



Anteroposterior radiograph of the knee demonstrat...

Anteroposterior radiograph of the knee demonstrating the medial plateau depression and prominent metaphyseal beaking (Langenskiöld stage II-III) typical of infantile genu varum regardless of age of presentation.

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Anteroposterior radiograph of the knee demonstrat...

Anteroposterior radiograph of the knee demonstrating the medial plateau depression and prominent metaphyseal beaking (Langenskiöld stage II-III) typical of infantile genu varum regardless of age of presentation.


Anteroposterior radiograph representing important...

Anteroposterior radiograph representing important angles for staging typical for the adolescent form. Obvious varus deformity in the proximal tibia with no sloping or bar formation is present (bars do not occur in the adolescent form). A: Tibiofemoral angle. B: Metaphyseal-diaphyseal angle. C: Metaphyseal-epiphyseal angle.

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Anteroposterior radiograph representing important...

Anteroposterior radiograph representing important angles for staging typical for the adolescent form. Obvious varus deformity in the proximal tibia with no sloping or bar formation is present (bars do not occur in the adolescent form). A: Tibiofemoral angle. B: Metaphyseal-diaphyseal angle. C: Metaphyseal-epiphyseal angle.

  • Radiographs of the knee are critical in assessing and staging the severity of the deformity. An anteroposterior standing radiograph of both lower extremities and a lateral radiograph of the involved extremity are used (see the top image above).
    • Fragmentation with a protuberant step deformity and beaking of the proximal medial tibial metaphysis are the major features of the infantile group. The lateral cortical wall of the upper tibial metaphysis is nearly straight.
    • Differentiating between severe physiologic bowing and infantile-type Blount disease is difficult in early childhood. Thus, corrective intervention is not recommended when the patient is younger than 2 years.
    • Early changes of infantile Blount disease can be assessed by measuring the metaphyseal-diaphyseal angle of the proximal tibia; that is, the angle formed by the intersection of a line through the transverse plane of the proximal tibial metaphysis with a line perpendicular to the long axis of the tibial diaphysis (see the lower image above).
    • The severity of the varus deformity is based on the tibiofemoral angle as measured on standing anteroposterior radiographs that include the ankle, knee, and most of the femur; the metaphyseal-diaphyseal angle; and the metaphyseal-epiphyseal angle, that is, the angle formed by the intersection of a line through the transverse plane of the proximal tibia epiphysis with a line through the transverse plane of the metaphysis (see the lower image above).

Histologic Findings

In the infantile form, bone changes include delayed ossification of the medial epiphysis and metaphysis of the proximal tibia.6 In all stages of the disease, histologic specimens from the zone of resting cartilage in the medial part of the proximal tibial physis have well-defined pathologic changes, as described in Pathophysiology. These consist of (1) islands of densely packed cells exhibiting more hypertrophy than expected on the basis of their position in the growth plate, (2) islands of fibrocartilage that are nearly acellular, and (3) abnormal groups of capillary vessels. No avascular necrosis of bone or inflammation has been demonstrated.5,13,18,21

Staging

Langenskiöld classified infantile tibia vara into 6 progressive stages, based on the degree of metaphyseal-epiphyseal changes observed on the radiograph. Severity of disease is based on the Langenskiöld stage and the age of the child.17,21,22

Anteroposterior radiograph representing important...

Anteroposterior radiograph representing important angles for staging typical for the adolescent form. Obvious varus deformity in the proximal tibia with no sloping or bar formation is present (bars do not occur in the adolescent form). A: Tibiofemoral angle. B: Metaphyseal-diaphyseal angle. C: Metaphyseal-epiphyseal angle.

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Anteroposterior radiograph representing important...

Anteroposterior radiograph representing important angles for staging typical for the adolescent form. Obvious varus deformity in the proximal tibia with no sloping or bar formation is present (bars do not occur in the adolescent form). A: Tibiofemoral angle. B: Metaphyseal-diaphyseal angle. C: Metaphyseal-epiphyseal angle.


More on Blount Disease

Overview: Blount Disease
Workup: Blount Disease
Treatment: Blount Disease
Follow-up: Blount Disease
Multimedia: Blount Disease
References
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References

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  2. Andrade N, Johnston CE. Medial epiphysiolysis in severe infantile tibia vara. J Pediatr Orthop. Sep-Oct 2006;26(5):652-8. [Medline].

  3. Wilson NA, Scherl SA, Cramer KE. Complications of high tibial osteotomy with external fixation in adolescent Blount's disease. Orthopedics. Oct 2007;30(10):848-52. [Medline].

  4. Accadbled F, Laville JM, Harper L. One-step treatment for evolved Blount's disease: four cases and review of the literature. J Pediatr Orthop. Nov-Dec 2003;23(6):747-52. [Medline].

  5. Blount WP. Tibia vara, osteochondrosis deformans tibiae. J Bone Joint Surg. 1937;19:1.

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  7. Wenger DR, Mickelson M, Maynard JA. The evolution and histopathology of adolescent tibia vara. J Pediatr Orthop. Jan 1984;4(1):78-88. [Medline].

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  11. Sevastikoglou JA, Eriksson I. Familial infantile osteochondrosis deformans tibiae. Idiopathic tibia vara. A case report. Acta Orthop Scand. 1967;38(1):81-7. [Medline].

  12. Davids JR, Huskamp M, Bagley AM. A dynamic biomechanical analysis of the etiology of adolescent tibia vara. J Pediatr Orthop. Jul-Aug 1996;16(4):461-8. [Medline].

  13. Golding JS, McNeil-Smith JD. Observations on the etiology of tibia vara. J Bone Joint Surg. 1963;45B:320.

  14. Grover JP, Vanderby R, Leiferman EM, Wilsman NJ, Noonan KJ. Mechanical behavior of the lamb growth plate in response to asymmetrical loading: a model for Blount disease. J Pediatr Orthop. Jul-Aug 2007;27(5):485-92. [Medline].

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  16. Arkin AA, Katz JF. The effects of pressure on epiphyseal growth: the mechanism of plasticity of growing bone. J Bone Joint Surgery Am. 1956;38:1056-76.

  17. Langenskiöld A. Tibia vara. Osteochondrosis deformans tibiae. A survey of 23 cases. Acta Chir Scand. 1952;103:1.

  18. Tachdjian MO, ed. The foot and leg: tibia vara. In: Pediatric Orthopedics. Vol 4. Philadelphia:. WB Saunders Co;1990:2835-50.

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  23. Lavelle WF, Shovlin J, Drvaric DM. Reliability of the metaphyseal-diaphyseal angle in tibia vara as measured on digital images by pediatric orthopaedic surgeons. J Pediatr Orthop. Sep 2008;28(6):695-8. [Medline].

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  28. Birch JG, Buech MF, Roach JW. Lateral tibia epiphysiodesis for adolescent Blount's disease. Orthop Trans. 1992;16:14.

  29. Coogan PG, Fox JA, Fitch RD. Treatment of adolescent Blount disease with the circular external fixation device and distraction osteogenesis. J Pediatr Orthop. Jul-Aug 1996;16(4):450-4. [Medline].

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  31. Stanitski DF, Dahl M, Louie K, Grayhack J. Management of late-onset tibia vara in the obese patient by using circular external fixation. J Pediatr Orthop. Sep-Oct 1997;17(5):691-4. [Medline].

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  33. Feldman DS, Madan SS, Ruchelsman DE, Sala DA, Lehman WB. Accuracy of correction of tibia vara: acute versus gradual correction. J Pediatr Orthop. Nov-Dec 2006;26(6):794-8. [Medline].

  34. Schoenecker PL, Johnston R, Rich MM, Capelli AM. Elevation of the medical plateau of the tibia in the treatment of Blount disease. J Bone Joint Surg Am. Mar 1992;74(3):351-8. [Medline].

  35. Ganel A, Heim M, Farine I. Asymmetric epiphyseal distraction in treatment of Blount's disease. Orthop Rev. Apr 1986;15(4):237-40. [Medline].

  36. Golding JS. Tibia vara. J Bone Joint Surg. 1962;44B:216.

  37. Pirpiris M, Jackson KR, Farng E, Bowen RE, Otsuka NY. Body mass index and Blount disease. J Pediatr Orthop. Sep-Oct 2006;26(5):659-63. [Medline].

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Further Reading

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Keywords

Blount's disease, Blount disease, osteochondrosis deformans tibiae, tibia vara, idiopathic tibia vara, infantile tibia vara, juvenile tibia vara, adolescent tibia vara, knee pain

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Contributor Information and Disclosures

Author

Matthew J DeOrio, MD, Staff Physician, Department of Orthopedic Surgery, Mayo Clinic of Rochester
Matthew J DeOrio, MD is a member of the following medical societies: American Medical Association and Florida Medical Association
Disclosure: Nothing to disclose.

Coauthor(s)

James K DeOrio, MD, Director of Foot and Ankle Fellowship Program, Assistant Professor of Orthopedic Surgery, Orthopedic Surgery, St Lukes Hospital, Jacksonville, Florida
James K DeOrio, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Foot and Ankle Society, Florida Medical Association, and German Society of Neurology
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Thomas M DeBerardino, MD, Associate Professor of Orthopaedic Surgery, University of Connecticut Health Center
Thomas M DeBerardino, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Association, and American Orthopaedic Society for Sports Medicine
Disclosure: Arthrex, Inc. Grant/research funds Other; Arthrex, Inc. Honoraria Speaking and teaching; Genzyme Biosurgery. Inc. Grant/research funds Other; Musculoskeletal Transplant Foundation Grant/research funds Other; Histogenics Grant/research funds None; Arthrex, Inc. Consulting fee Speaking and teaching

CME Editor

Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital
Dinesh Patel, MD, FACS is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Association of Physicians of Indian Origin, American College of International Physicians, and American College of Surgeons
Disclosure: Nothing to disclose.

Chief Editor

Carlos J Lavernia, MD, FAAOS, Adjunct Clinical Professor, Department of Orthopedic Surgery, University of Miami School of Medicine; Medical Director, Orthopedic Institute at Mercy Hospital
Carlos J Lavernia, MD, FAAOS is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Association of Hip and Knee Surgeons, Arthritis Foundation, Biomedical Engineering Society, Florida Orthopaedic Society, and Orthopaedic Research Society
Disclosure: Zimmer Stock Implant Designer

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