A shape completion model for corrective osteotomy of distal radius malunion

Area of Science:

• Orthopedic surgery
• Medical imaging
• Computer-aided design

Background:

• Distal radius malunion often requires 3D planning for osteotomies.
• The contralateral radius is a common template, but unsuitable in ~10% of cases.
• A shape completion model offers an alternative by generating a healthy radius model.

Purpose of the Study:

• To develop and clinically evaluate a shape completion model for reconstructing healthy radius models.
• To provide a viable alternative for 3D planning when the contralateral radius is unavailable.

Main Methods:

• A statistical shape model (SSM) was trained on 80 CT scans of healthy radii.
• The SSM was used to create a shape completion model predicting the distal 12% from the proximal 88%.
• Model performance was tested on 10 reserved CT scans.

Main Results:

• The shape completion model generated clinically viable 3D radius reconstructions.
• Mean rotational errors were low: radial inclination (2.6°), volar tilt (3.6°), and axial rotation (2.6°).
• Mean translational errors were also minimal: dorsal shift (0.7 mm), radial shift (0.8 mm), and lengthening (1.7 mm).

Conclusions:

• The developed shape completion model is viable for 3D planning in cases lacking a healthy contralateral radius.
• Clinical application in patients with a healthy contralateral radius is not yet recommended due to error margins.
• Length mismatch, the most significant error, can be corrected during 3D planning using the ulna as a reference.