Abstract
BackgroundCodman’s paradox reveals a misunderstanding of geometry in orthopedic practice. Physicians often encounter situations that cannot be understood intuitively during orthopedic interventions such as corrective osteotomy. Occasionally, unexpected angular or rotational deformity occurs during surgery.This study aimed to draw the attention of orthopedic surgeons toward the concepts of orientation and rotation and demonstrate the potential for unexpected deformity after orthopedic interventions. This study focused on three situations: shoulder arthrodesis, femoral varization derotational osteotomy, and femoral derotation osteotomy.MethodsFirst, a shoulder model was generated to calculate unexpected rotational deformity to demonstrate Codman’s paradox. Second, femoral varization derotational osteotomy was simulated using a cylinder model. Third, a reconstructed femoral model was used to calculate unexpected angular or rotational deformity during femoral derotation osteotomy.ResultsUnexpected external rotation was found after forward elevation and abduction of the shoulder joint. In the varization and derotation model, closed-wedge osteotomy and additional derotation resulted in an unexpected extension and valgus deformity, namely, under-correction of coxa valga. After femoral derotational osteotomy, varization and extension of the distal fragment occurred, although the extension was negligible.ConclusionsSurgeons should be aware of unexpected angular deformity after surgical procedure involving bony areas. The degree of deformity differs depending on the context of the surgical procedure. However, this study reveals that notable deformities can be expected during orthopedic procedures such as femoral varization derotational osteotomy.
Highlights
Codman’s paradox reveals a misunderstanding of geometry in orthopedic practice
After surgery, the surgeon found that internal rotation of the shoulder was less than 40 degrees because unexpected external rotation of the shoulder can occur during sequential movement of the arm
In the shoulder model, unexpected external rotation of the arm occurred after two-plane motion
Summary
Codman’s paradox reveals a misunderstanding of geometry in orthopedic practice. Physicians often encounter situations that cannot be understood intuitively during orthopedic interventions such as corrective osteotomy. This study aimed to draw the attention of orthopedic surgeons toward the concepts of orientation and rotation and demonstrate the potential for unexpected deformity after orthopedic interventions. In the anatomic position of the shoulder joint, the palm is positioned anteriorly. If the arm is forward elevated to 360 degrees, the palm will face anteriorly. During arthrodesis of the shoulder for severe arthritis of the shoulder joint, a surgeon set the patient’s shoulder position to 30 degrees flexion, 20 degrees abduction, and 40 degrees internal rotation sequentially from the neutral position. After surgery, the surgeon found that internal rotation of the shoulder was less than 40 degrees because unexpected external rotation of the shoulder can occur during sequential movement of the arm
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