The Rule of 57: Orthopaedic Trigonometry Made Easy.
expert_opinion · Level V
Where this comes from
- Record sourced from PubMed, PMID 30939568.
- Also identified by DOI 10.5435/JAAOS-D-18-00677.
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Abstract
The Rule of 57 is an easy method for planning osteotomies and calculating translations when correcting spine and limb deformities. The rule is based on the mathematical principle that a circle with a radius of 57 mm has a circumference of 360 mm where each 1° of the circle subtends an arc of 1 mm in length. Thus a 1 mm opening or closing wedge osteotomy with a width of 57 mm would result in 1° of angular correction. This basic geometric shape can be extrapolated in many ways to determine proper alignment for preoperative planning, performing osteotomies, understanding guided growth, and executing a variety of deformity corrections.
Medical subject headings
- Bone Malalignment
- Orthopedic Procedures
- Osteotomy