The accuracy and precision of radiostereometric analysis in monitoring tibial plateau fractures

Figures & data

Figure 1. Lateral view (panel a) and anterior view (panel b) of the tibia showing marker placement in the reference segment. ★ segment A, ▪ segment B, ♦ segment C, ▴ segment D, × segment E, ○ segment F.

Figure 2. Medial (a) and lateral (b) views of fracture fragment demonstrating marker placement on the fracture fragment. The solid circle represents the fracture segment markers visible after reduction and fixation.

Figure 3. Synbone model of a lateral tibial plateau fracture attached to a translation and rotation stage.

Figure 4. Radiographs of the application of RSA in vivo. Focus 1 (panel a) and focus 2 (panel b).

Table 1. Translation accuracy

Tibial segment			x-axis (lateral)				Translation accuracy y-axis (distal)				z-axis (posterior)
A	B	C	D	E	F	G	D	E	F	G	D	E	F	G
Fracture fragment: 9 markers, condition number 76
A	9	79	0.017	0.012	± 0.007	0.022	–0.004	–0.005	± 0.006	0.012	0.025	0.027	± 0.007	0.029
B	9	68	–0.036	-0.036	± 0.015	0.047	0.036	0.044	± 0.008	0.040	–0.016	–0.013	± 0.018	0.038
C	9	51	–0.001	–0.003	± 0.008	0.015	–0.005	–0.006	± 0.008	0.016	0.090	0.096	± 0.013	0.094
D	9	107	–0.005	0.000	± 0.015	0.030	0.024	0.031	± 0.010	0.032	–0.044	–0.050	± 0.027	0.070
E	9	71	0.004	0.005	± 0.012	0.025	0.004	0.010	± 0.010	0.020	–0.048	–0.050	± 0.019	0.062
F	9	40	–0.003	–0.002	± 0.009	0.019	0.012	0.006	± 0.018	0.038	–0.003	0.002	± 0.007	0.014
Fracture fragment: 6 markers, condition number 94
A	6	96	0.014	0.009	± 0.007	0.020	0.010	0.010	± 0.005	0.014	0.023	0.023	± 0.007	0.027
B	6	103	–0.028	–0.032	± 0.017	0.044	0.086	0.090	± 0.011	0.089	–0.009	–0.001	± 0.019	0.040
C	6	66	0.007	0.007	± 0.008	0.017	0.015	0.012	± 0.016	0.035	0.081	0.082	± 0.014	0.085
D	6	130	–0.005	0.014	± 0.019	0.039	0.025	0.029	± 0.010	0.032	–0.011	–0.008	± 0.033	0.068
E	6	121	0.028	0.029	± 0.013	0.039	–0.009	–0.006	± 0.009	0.019	–0.009	–0.011	± 0.017	0.044
F	6	50	–0.007	–0.002	± 0.010	0.021	0.005	–0.001	± 0.018	0.037	–0.005	–0.004	± 0.007	0.015
Fracture fragment: 3 markers, condition number 141
A	3	148	0.019	0.015	± 0.007	0.024	0.001	–0.001	± 0.006	0.011	0.022	0.024	± 0.007	0.026
B	3	134	–0.107	–0.139	± 0.034	0.127	0.094	0.088	± 0.015	0.099	0.006	0.013	± 0.032	0.066
C	3	133	0.011	0.010	± 0.008	0.018	–0.005	–0.006	± 0.008	0.016	0.060	0.061	± 0.032	0.072
D	3	180	0.002	–0.002	± 0.045	0.091	0.085	0.083	± 0.013	0.088	0.097	0.100	± 0.016	0.102
E	3	169	0.022	0.022	± 0.016	0.039	–0.010	–0.009	± 0.011	0.025	0.019	0.025	± 0.035	0.075
F	3	127	–0.046	–0.050	± 0.012	0.052	–0.021	–0.027	± 0.016	0.038	0.008	0.015	± 0.013	0.027

A Reference

B Number of markers

C Condition number

D Mean

E Median

F 95% confidence interval

G Root mean square error

Table 2. Translation precision

Tibial segment			x-axis (lateral)			Translation precision y-axis (distal)			z-axis (posterior)
A	B	C	D	E	F	D	E	F	D	E	F
Fracture fragment: 9 markers, condition number 76
A	9	79	0.003	0.003	± 0.012	0.097	0.099	± 0.007	–0.051	–0.049	± 0.024
B	9	68	–0.068	–0.069	± 0.016	0.095	0.095	± 0.009	0.002	0.018	± 0.026
C	9	51	–0.027	–0.033	± 0.012	0.087	0.088	± 0.015	–0.076	–0.071	± 0.043
D	9	107	–0.068	–0.083	± 0.035	0.101	0.104	± 0.011	0.016	0.020	± 0.083
E	9	71	–0.058	–0.061	± 0.018	0.081	0.079	± 0.021	–0.060	–0.054	± 0.031
F	9	40	–0.043	–0.039	± 0.009	0.107	0.106	± 0.006	–0.007	–0.011	± 0.024
Fracture fragment: 6 markers, condition number 94
A	6	96	0.011	0.011	± 0.011	0.102	0.107	± 0.008	–0.050	–0.045	± 0.022
B	6	103	–0.073	–0.071	± 0.021	0.098	0.091	± 0.018	0.007	0.010	± 0.024
C	6	66	–0.022	–0.023	± 0.011	0.069	0.075	± 0.021	–0.098	–0.094	± 0.041
D	6	130	–0.077	–0.079	± 0.032	0.091	0.094	± 0.012	0.004	0.007	± 0.085
E	6	121	–0.043	–0.040	± 0.023	0.079	0.084	± 0.021	–0.092	–0.072	± 0.074
F	6	50	–0.033	–0.029	± 0.016	0.116	0.116	± 0.004	–0.019	–0.017	± 0.012
Fracture fragment: 3 markers, condition number 141
A	3	148	0.003	0.000	± 0.012	0.107	0.109	± 0.015	–0.059	–0.056	± 0.027
B	3	134	–0.106	–0.106	± 0.019	0.107	0.100	± 0.021	0.043	0.053	± 0.037
C	3	133	–0.030	–0.025	± 0.014	0.058	0.057	± 0.025	–0.111	–0.128	± 0.052
D	3	180	–0.109	–0.117	± 0.032	0.097	0.096	± 0.021	0.047	0.044	± 0.054
E	3	169	–0.051	–0.060	± 0.033	0.081	0.078	± 0.036	–0.073	–0.071	± 0.069
F	3	127	–0.038	–0.029	± 0.021	0.130	0.131	± 0.005	–0.012	0.001	± 0.028

A–F: See Table 1

Table 3. Rotation accuracy

			Rotation accuracy
Tibial segment			x-axis (negative)				x-axis (positive)
A	B	C	D	E	F	G	D	E	F	G
Fracture fragment: 9 markers, condition number 76
A	9	79	–0.11	–0.12	± 0.039	0.125	–0.04	–0.04	± 0.040	0.066
B	9	68	–0.13	–0.14	± 0.040	0.137	–0.06	–0.06	± 0.049	0.086
C	9	51	–0.07	–0.08	± 0.036	0.087	0.00	–0.01	± 0.043	0.058
D	9	107	–0.05	–0.06	± 0.035	0.071	–0.01	–0.03	± 0.041	0.055
E	9	71	–0.05	–0.05	± 0.043	0.076	–0.01	–0.03	± 0.037	0.050
F	9	40	–0.13	–0.13	± 0.037	0.138	–0.07	–0.06	± 0.041	0.092
Fracture fragment: 6 markers, condition number 94
A	6	96	–0.11	–0.13	± 0.045	0.129	–0.12	–0.11	± 0.034	0.126
B	6	103	–0.13	–0.13	± 0.045	0.145	–0.12	–0.10	± 0.071	0.149
C	6	66	–0.07	–0.08	± 0.045	0.095	0.03	0.02	± 0.037	0.059
D	6	130	–0.01	–0.02	± 0.037	0.050	0.01	0.02	± 0.040	0.055
E	6	121	0.01	–0.00	± 0.041	0.055	–0.02	–0.02	± 0.038	0.052
F	6	50	–0.11	–0.10	± 0.038	0.118	–0.11	–0.10	± 0.037	0.123
Fracture fragment: 3 markers, condition number 141
A	3	148	–0.10	–0.11	± 0.039	0.109	–0.10	–0.11	± 0.040	0.113
B	3	134	–0.16	–0.14	± 0.061	0.180	–0.09	–0.09	± 0.076	0.139
C	3	133	–0.05	–0.03	± 0.052	0.084	0.04	0.06	± 0.039	0.065
D	3	180	–0.10	–0.11	± 0.037	0.111	0.06	0.06	± 0.046	0.083
E	3	169	–0.04	–0.02	± 0.045	0.072	0.01	–0.02	± 0.057	0.077
F	3	127	–0.14	–0.13	± 0.062	0.164	–0.07	–0.08	± 0.040	0.085

A–G: See Table 1

Table 4. Rotation precision

						Rotation precision
Tibial segment			x-axis			y-axis			z-axis
A	B	C	D	E	F	D	E	F	D	E	F
Fracture fragment: 9 markers, condition number 76
A	9	79	–0.16	–0.16	± 0.018	–0.08	–0.08	± 0.047	–0.04	–0.03	± 0.019
B	9	68	–0.12	–0.11	± 0.040	0.10	0.09	± 0.033	–0.04	–0.03	± 0.020
C	9	51	–0.13	–0.11	± 0.032	0.00	0.00	± 0.029	–0.03	–0.03	± 0.029
D	9	107	–0.11	–0.11	± 0.020	0.12	0.13	± 0.085	–0.04	–0.04	± 0.016
E	9	71	–0.11	–0.11	± 0.029	0.02	0.02	± 0.046	–0.02	–0.01	± 0.013
F	9	40	–0.12	–0.13	± 0.028	0.09	0.09	± 0.013	–0.05	–0.06	± 0.017
Fracture fragment: 6 markers, condition number 94
A	6	98	–0.11	–0.12	± 0.022	–0.09	–0.09	± 0.034	–0.03	–0.02	± 0.024
B	6	103	–0.10	–0.12	± 0.065	0.13	0.14	± 0.050	–0.03	–0.03	± 0.024
C	6	66	–0.11	–0.11	± 0.033	–0.02	–0.02	± 0.036	0.01	0.01	± 0.032
D	6	130	–0.11	–0.11	± 0.025	0.17	0.19	± 0.095	–0.03	–0.02	± 0.023
E	6	121	–0.10	–0.10	± 0.028	0.00	0.00	± 0.064	–0.01	–0.01	± 0.020
F	6	50	–0.09	–0.10	± 0.024	0.07	0.08	± 0.016	–0.06	–0.06	± 0.019
Fracture fragment: 3 markers, condition number 141
A	3	148	–0.11	–0.12	± 0.031	–0.05	–0.02	± 0.040	–0.05	–0.06	± 0.051
B	3	134	–0.09	–0.11	± 0.084	0.20	0.17	± 0.060	–0.06	–0.07	± 0.063
C	3	133	–0.16	–0.15	± 0.044	–0.01	0.00	± 0.043	–0.02	–0.04	± 0.050
D	3	180	–0.08	–0.08	± 0.021	0.17	0.21	± 0.111	–0.03	–0.02	± 0.051
E	3	169	–0.09	–0.12	± 0.046	–0.00	0.01	± 0.058	–0.03	–0.03	± 0.074
F	3	127	–0.10	–0.09	± 0.033	0.10	0.10	± 0.065	–0.13	-0.13	± 0.045

A–F: See Table 1