Published in:
01-08-2017 | Knee
Radiographic measurement of the posterior femoral offset is not precise
Authors:
Jean-Yves Jenny, Sophie Honecker, Yves Chammai
Published in:
Knee Surgery, Sports Traumatology, Arthroscopy
|
Issue 8/2017
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Abstract
Purpose
The posterior femoral offset may significantly impact the final flexion range after total knee arthroplasty (TKA). The purpose of the present study was to compare a conventional, radiologic-based technique with an intra-operative, surgical navigation-based technique for the measurement of posterior femoral offset. The tested hypothesis was that the two measurement techniques produce different results both before and after TKA.
Methods
One-hundred consecutive cases referred for end-stage knee osteoarthritis have been studied. Posterior femoral offsets, measured pre- and post-TKA from radiographs, as well as those measured from a navigation system intra-operatively, were analysed. The pre-TKA measured offsets, post-TKA measured offsets and the changes (pre- vs. post-TKA) in the offsets were statistically compared between the radiologic and the navigated measurement techniques at a 0.05 level of significance.
Results
The mean paired difference between pre-TKA radiologic and navigated measurement was 4 ± 4 mm (p < 0.001). There was a significant and moderate positive correlation with a good coherence between the two measurements. The mean paired difference between post-TKA radiologic and navigated measurement was 6 ± 5 mm (p < 0.001). There was a significant and moderate positive correlation but a poor coherence between the two measurements.
Conclusions
The conventional radiologic technique for the measurement of the posterior femoral offset cannot be reliably used either for pre-TKA planning of the posterior femoral resection and antero-posterior sizing of the femoral component, or for post-TKA quality control of the reconstruction of the posterior femoral offset.
Level of evidence
Level IV.