Measurement of bone mineral density is possible with standard radiographs: A study involving total knee replacement

Figures & data

Figure 1. Definition of ROI-1 and ROI-2 in radiographs and DXA scans.

Figure 2. ROIs and density measurement by the optical method.

Table 1.  Mean of density in the three ROIs at 12 and 24 months, and relationship regarding gender of patients

Technique Follow-up (months)	Sex	Mean	SD	P-value^a
DXA
12	Men	0.96	0.11	0.002
	Women	0.84	0.075
24	Men	0.93	0.096	0.001
	Women	0.81	0.069
Radiographs
12	Men	147	15	0.005
	Women	128	9.22
24	Men	137	14	0.01
	Women	123	12

^aMann-Whitney U-test

Table 2.  Density obtained in the three ROIs, and average at 12 and 24 months

Technique	12 months		24 months		P-value^a
ROI	Mean	SD	Mean	SD
DXA
1	0.88	0.12	0.85	0.12	0.003
2	0.78	0.14	0.77	0.12	0.04
3	0.97	0.09	0.92	0.09	< 0.001
M2	0.83	0.12	0.81	0.11	< 0.001
M3	0.88	0.10	0.84	0.09	< 0.001
Radiographs
1	136	17	127	18	< 0.001
2	114	20	112	22	< 0.001
3	152	14	143	14	< 0.001
M2	125	16	120	17	< 0.001
M3	134	14	127	14	< 0.001

^aWilcoxon test

Figure 3. Bland and Altman plots for M2 and M3 at 12 and 24 months.Average of DXA (g/cm²) and optical density (gray-scale value) is shown on the horizontal axis.DXA (g/cm²) – optical density (gray-scale value) is shown on the vertical axis.