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Published on: July 2, 2021
Agreement between radiological and computer navigation measurement of lower limb alignment
Julian Dexel1, Stephan Kirschner, Klaus-Peter Günther
1Department of Orthopaedic Surgery, University Hospital Carl Gustav Carus, Technical University of Dresden, Fetscherstr. 74, 01307, Dresden, Germany, julian.dexel@uniklinikum-dresden.de.
Summary
Accurate long-leg standing radiographs (LLRs) are crucial for knee surgery planning. Even with neutral rotation, differences between LLRs and navigation data exist, suggesting both methods remain valuable for assessing limb alignment.
Area of Science:
- Orthopedic Surgery
- Medical Imaging
- Biomechanical Engineering
Background:
- Accurate limb alignment is vital for successful reconstructive knee surgery.
- Preoperative planning and intraoperative execution rely on precise alignment measurements.
- Computer-assisted navigation systems offer potential for enhanced accuracy in total knee arthroplasty (TKA).
Purpose of the Study:
- To compare limb alignment measurements from long-leg standing radiographs (LLRs) with intraoperative data from a navigation system.
- To evaluate the impact of radiographic quality on the agreement between LLRs and navigation measurements.
- To determine the reliability of LLRs in the context of computer-assisted TKA.
Main Methods:
- Analysis of 135 consecutive patients undergoing computer-assisted TKA.
- Classification of long-leg radiograph (LLR) technical quality (good, acceptable, poor) based on leg rotation.
- Assessment of the difference between radiographic and navigation measurements of leg alignment.
Main Results:
- Preoperative LLRs were rated good in 56.3% and acceptable in 37.0%.
- The median difference between radiographic and navigation measurements increased with poorer LLR quality (good: 1.5°, acceptable: 2.5°, poor: 4.5°).
- For good quality preoperative LLRs, the median difference was 1.7°, decreasing to 1.2° postoperatively.
Conclusions:
- Low differences in lower limb alignment measurements are observed when LLRs are obtained with neutral rotation.
- Significant differences can still occur even with ideal radiographic conditions, and the more accurate measurement remains uncertain.
- Long-leg standing radiographs should continue to be used alongside navigation systems in knee surgery.