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Updated: Mar 19, 2026
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Three-Dimensional Preoperative Virtual Planning in Derotational Proximal Femoral Osteotomy
Published on: February 17, 2023
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Electromagnetic bone segment tracking to control femoral derotation osteotomy-A saw bone study
Andreas Geisbüsch1, Christoph Auer1, Hartmut Dickhaus2
1Department of Orthopaedic and Trauma Surgery, University Hospital Heidelberg, Schlierbacher Landstraße 200a, Heidelberg 69117, Baden-Württemberg, Germany.
Summary
A new electromagnetic tracking system significantly improves the accuracy of femoral derotation surgery in children, reducing measurement errors common with traditional goniometers and enhancing patient safety.
Area of Science:
- Pediatric Orthopaedics
- Surgical Navigation Systems
- Gait Abnormalities Correction
Background:
- Femoral derotation osteotomy is a standard surgical procedure for correcting rotational gait abnormalities in children, particularly those with cerebral palsy.
- Current surgical outcomes show significant variability, with reported over- or under-correction, suggesting intraoperative measurement inaccuracies or loss of correction.
- Conventional methods like goniometry are prone to observer bias and lack precision, leading to suboptimal surgical results.
Purpose of the Study:
- To investigate the sources of error in femoral derotation procedures.
- To evaluate the accuracy and utility of a novel instrumented measurement system using electromagnetic tracking.
- To enhance the precision of rotational correction during pediatric orthopaedic surgery.
Main Methods:
- A supracondylar derotation osteotomy was performed on 21 artificial femur sawbones.
- Rotational correction was measured intraoperatively using both the new electromagnetic tracking system and conventional goniometry by nine raters.
- Accuracy of both systems was validated against reference measurements obtained from computed tomography scans.
Main Results:
- The electromagnetic tracking system demonstrated high accuracy, with measurements differing only by 0.1° ± 1.6° from the reference.
- Conventional goniometry exhibited substantial inter-rater variability (range: 10.8° ± 6.9°), indicating significant observer bias.
- The tracking system reliably detected unintentional changes in correction angle during osteosynthesis fixation (mean absolute change: 4.0° ± 3.2°).
Conclusions:
- Conventional methods for measuring femoral derotation are susceptible to significant observer bias.
- The newly developed instrumented tracking system provides accuracy better than ±2°, offering a substantial improvement over traditional techniques.
- This tracking system represents a significant advancement towards more reliable and safer femoral rotational correction in pediatric orthopaedic surgery.
