Table 2.
Summary of wear measurements
| Device type | Number of retrievals | Backside wear | Through-thickness wear | |||
|---|---|---|---|---|---|---|
| Depth (mm) | Rate (mm/year) | Volumetric rate (mm3/year) | Depth (mm) | Rate (mm/year) | ||
| Sigma® RP | ||||||
| Curved (CR) | 27 | 0.08 ± 0.08 | 0.06 ± 0.26 | |||
| PS | 67 | 0.08 ± 0.10 | 0.03 ± 0.05 | |||
| Total RPs | 94 | NA | NA | NA | 0.08 ± 0.09 | 0.04 ± 0.15 |
| Sigma® fixed bearing Ti trays | ||||||
| Posterior lipped (CR) | 19 | 0.10 ± 0.11 | 0.02 ± 0.02 | 31 ± 38 | 0.48 ± 0.33 | 0.08 ± 0.04 |
| Curved (CR) | 85 | 0.24 ± 0.26 | 0.03 ± 0.03 | 65 ± 78 | 0.65 ± 0.61 | 0.08 ± 0.08 |
| PS | 77 | 0.17 ± 0.27 | 0.02 ± 0.03 | 42 ± 53 | 0.68 ± 0.76 | 0.10 ± 0.08 |
| Total Ti tray | 181 | 0.20 ± 0.23 | 0.02 ± 0.03 | 51 ± 66 | 0.65 ± 0.66 | 0.09 ± 0.08 |
| Sigma® fixed bearing CoCr trays | ||||||
| Posterior lipped (CR) | 4 | 0.02 ± 0.02 | 0.01 ± 0.01 | 22 ± 26 | −0.003 ± 0.04 | −0.008 ± 0.03 |
| Curved (CR) | 12 | 0.03 ± 0.03 | 0.02 ± 0.02 | 38 ± 44 | −0.02 ± 0.04 | −0.02 ± 0.03 |
| PS | 21 | 0.005 ± 0.04 | −0.003 ± 0.03 | −9 ± 42 | 0.003 ± 0.04 | −0.01 ± 0.05 |
| Total CoCr tray | 37 | 0.01 ± 0.23 | 0.006 ± 0.02 | 10 ± 46 | −0.005 ± 0.04 | −0.01 ± 0.04 |
| Total fixed bearings | 218 | 0.17 ± 0.24 | 0.02 ± 0.03 | 44 ± 65 | 0.52 ± 0.65 | 0.07 ± 0.08 |
Values are expressed as mean ± SD; RP = rotating platform; CR = cruciate retaining; PS = posterior stabilized; Ti = titanium; CoCr = cobalt-chrome; NA = not applicable.