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A novel technique to assess rotational deformities in lower extremities using CT-based motion analysis
Peyman Bakhshayesh1,2, Ugwunna Ihediwa3, Sukha Sandher3
1Karolinska Institutet Karolinska University Hospital, Stockholm, Sweden. peyman.bakhshayesh@ki.se.
Scientific Reports
|October 27, 2021
Summary
A new digital technique accurately measures rotational deformities in lower legs after intramedullary nailing. This method offers a less biased alternative to traditional assessments for orthopedic surgery.
Area of Science:
- Orthopedic Surgery
- Biomechanical Engineering
- Medical Imaging
Background:
- Rotational deformities after intramedullary nailing of the tibia occur in up to 20% of cases.
- Current measurement methods rely on manual calculations from clinical assessments, X-rays, or CT scans, introducing potential bias.
- Previous research established rigorous motion analysis and symmetry studies on various anatomical structures and implants.
Purpose of the Study:
- To introduce a novel, fully digital technique for measuring rotational deformities in the lower legs.
- To overcome the inherent biases associated with manual calculation in existing measurement techniques.
- To provide a more objective and reproducible method for assessing post-surgical rotational alignment.
Main Methods:
- Utilized Computed Tomography (CT) images from 10 pairs of human lower legs, following institutional approval.
- Reconstructed three-dimensional CT images bilaterally and employed CT-based motion analysis (CTMA).
- Merged mirrored images of the left leg with the right leg, calculating discrepancies in translation and rotation automatically.
Main Results:
- Observed greater variation in the sagittal plane's Center of Mass (COM) translation (95% CI -2.959 to -0.292).
- Identified rotational differences along the anteroposterior (Y) axis (95% CI 0.370 to 1.035), suggesting a tendency towards varus in the right lower legs.
- Found no statistically significant differences in rotational deformities in the coronal or axial planes.
Conclusions:
- The novel, fully digital CTMA technique demonstrates that adult lower legs are symmetrical in the axial and coronal planes.
- Sagittal plane differences were detected, warranting further investigation with larger sample sizes.
- This commercially available, digital technique offers a viable, less biased alternative for clinical assessment of rotational deformities post-orthopedic surgery.
