Congenital Radial Ulnar Synostosis

Introduction

In normal development the radius and ulna divide from distal to proximal
- therefore the synostosis is usually in proximal half
Epidemiology
- bilateral in 60%
Genetics
- familial cases with autosomal dominant inheritance has been reported
- patients frequently have duplication in sex-chromosome

Presentation

Physical exam
- children often present at 3-5 years of age
  - no pronation or supination
  - fixed in varying degree of pronation (50% of patients have > 50° of pronation)

Imaging

Radiographs
- recommended view
  - ap and lateral of forearm and elbow
- findings
  - can see proximal synostosis
  - radius is heavy and bowed

Studies

Chromosome analysis
- to identify duplication in sex chromosomes

Treatment

Nonoperative
- observation
  - indications
    - usually preferred treatment, especially if deformity is unilateral
Operative
- osteotomy with fusion
  - indications
    - indicated to obtain functional degree of pronation
      - if unilateral set in pronation of 10-20°
      - if condition is bilateral than fix dominant arm in pronation (30-45°) and other in supination (20-35°)
  - technique
    - use percutaneous pins to aid fusion
    - perform at ~ 5 years of age
    - cannot recreate proximal radial-ulnar joint as it will reossify and recur

TAG

(OBQ08.140) The parents of a 2-year-old girl are concerned that their daughter has difficulty feeding herself from a bottle. They have noticed that she rotates her elbow in front of her body when trying to bring the bottle to her mouth. Physical exam demonstrates 10 degrees of elbow hyperextension and 160 degrees of flexion. The forearm does not actively or passively rotate. A radiograph is provided in figure A. Which of the following would be an indication for a future surgical intervention? Topic

Review Topic

FIGURES: A

1. Forearm fixed in 45 degrees of pronation
2. Forearm fixed in 30 degrees of supination
3. Patient younger than 3 years of age
4. An affected older sibling
5. Bilateral involvement

PREFERRED RESPONSE ▶

DISCUSSION: Radiograph demonstrates proximal radioulnar synostosis. This rare congenital deformity is most frequently a pronation deformity, but is not frequently a functionally limiting deformity. Observation is the treatment of choice in most cases. Surgical osteotomy and fusion is beneficial for bilateral involvement with the objective of achieving one arm fixed in modest pronation and the other fixed in modest supination to facilitate competence in activities of daily living and hygeine. Surgical excision and reconstruction has not demonstrated successful outcomes.

REFERENCES:

1. Waters, PM. Lovell and Winter’s Pediatric Orthopedics. Lippincott, Williams, and Wilkins. 2005: pp 937-939

Question Authors:

John Badylak MD,

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Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Waters, PM. Lovell and Winter’s Pediatric Orthopedics. Lippincott, Williams, and Wilkins. 2005: pp 937-939

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