Efficacy of a novel iPod-based navigation system compared to traditional navigation system in total knee arthroplasty

Figures & data

Figure 1. Flowchart showing sequence of intraoperative registration and recording done for both systems during this study.

Table 1. Correlation between intraoperative parameters measured with both navigation systems.

	Ci^® system		DASH^® system
Parameters	Mean ± SD	Median (range)	Mean ± SD	Median (range)	Correlation coefficient (r)	p Value
Preoperative coronal deformity (degrees)	9.6 ± 8.9	10 (−15 to 25)	9.4 ± 8.8	9.2 (−14.5 to 27)	0.98	<0.001
Preoperative sagittal deformity (degrees)	5.9 ± 4.8	5 (−1.5 to 17)	6 ± 4.9	4.7 (−2 to 17)	0.86	<0.001
Tibial cut thickness (mm)	7.3 ± 1.4	7.5 (4 to 10.5)	8 ± 1.6	8 (4.5 to 10)	0.67	<0.001
Tibial cut coronal plane (degrees)	0.1 ± 0.5	0.0 (−1 to 1)	−0.1 ± 1.1	0.0 (−2.5 to 2)	0.32	0.05
Tibial slope (degrees)	3.2 ± 0.6	3.2 (1.5 to 4.5)	3.2 ± 0.9	3.5 (1 to 5)	0.29	0.08
Femoral cut thickness (mm)	9.4 ± 1.6	9.5 (6 to 13)	9.5 ± 1.7	9.5 (6 to 14)	0.71	<0.001
Femoral cut coronal plane (degrees)	0.1 ± 0.7	0.2 (−1 to 2)	0.1 ± 1	0.5 (−2.5 to 2.5)	0.62	<0.001
Femoral cut sagittal plane (degrees)	2.1 ± 1.4	1.7 (−1.5 to 5)	2.4 ± 1.5	2.5 (0 to 6.5)	0.88	<0.001
Femoral rotation (degrees)	2.0 ± 2.1	2 (−2 to 6.5)	0.4 ± −0.2	0.7 (−8 to 8)	0.29	0.08
Postoperative coronal alignment (degrees)	0.5 ± 0.8	0.5 (−1 to 2)	0.5 ± 1.2	0.5 (−3 to 3)	0.76	<0.001
Postoperative sagittal alignment (degrees)	4.1 ± 1.2	4.2 (1.5 to 6)	4.2 ± 1.2	4 (2 to 6.5)	0.91	<0.001
Postoperative knee flexion (degrees)	121.6 ± 8.6	121 (105 to 148)	121.8 ± 8.7	120.7 (105 to 150)	0.99	<0.001

SD – standard deviation, p-value <0.05 is significant.

For coronal deformity/alignment and coronal plane of tibial/femoral cut, positive value implies varus and negative value implies valgus.

For sagittal deformity/alignment and sagittal plane of tibial/femoral cut, positive value implies flexion and negative value implies extension.

For femoral rotation, positive value implies external rotation and negative value implies internal rotation of the femoral component.