An accelerometer-based navigation did not improve the femoral component positioning compared to a modified conventional technique of pre-operatively planned placement of intramedullary rod in total knee arthroplasty
Tsukeoka, T., Tsuneizumi, Y. & Yoshino, K.Knee
Introduction
Although the most commonly used method of femoral component alignment in total knee arthroplasty (TKA) is intramedullary (IM) guides, this method demonstrated a limited degree of accuracy. Because of the femoral anterior bowing, the tip of the guide rod will impinge on the anterior cortex if a long rod is inserted. We hypothesized that the pre-operative planned insertion depth of the rod could increase the accuracy of the femoral component positioning in conventional TKA (modified conventional technique). Accelerometer-based, portable navigation device has been postulated to have better accuracy than conventional TKA in component positioning. The purpose of this study was to compare the post-operative femoral component alignment of TKA using the modified conventional technique with the accelerometer-based navigation.
Materials and methods
Fifty-five knees underwent TKA using the modified conventional technique and femoral component positioning was compared with 55 knees performed using the accelerometer-based navigation device. The femoral component alignment was evaluated with a CT-based three-dimensional software.
Results
The mean absolute deviation from targeted alignment in the sagittal plane was significantly less in the modified conventional cohort than in the accelerometer-based navigation cohort (1.1° vs 2.6°, P < 0.001). In the modified conventional cohort, 96.4% had an alignment within 3° of a targeted angle in the coronal plane (vs 89.1% with the accelerometer-based navigation, P = 0.14), and 96.4% in the sagittal plane (vs 74.5% with the accelerometer-based navigation, P < 0.001).
Conclusion
The modified conventional technique is a simple and equal to or more accurate method than the accelerometer-based navigation in positioning the femoral component in TKA at a mid-volume hospital.
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