| Variable | Condition | Union | Nonunion | SE | ||
| Count | Percentage | Count | Percentage | |||
| Age | Aged less than 55 years | 12 | 100 | 0 | 0 | P = 0.16 |
| 56 - 65 | 2 | 100 | 0 | 0 | ||
| 66 - 75 | 10 | 71.4 | 4 | 28.6% | ||
| 76 - 85 | 16 | 80 | 4 | 20% | ||
| More than 85 years | 8 | 100 | 0 | 0 | ||
| Gender | Male | 28 | 96.6 | 1 | 3.4% | P = 0.023 |
| Female | 20 | 74.1 | 7 | 25.9% | ||
| AO/OTA | A1 | 13 | 86.7 | 2 | 13.3% | P = 0.99 |
| A2 | 23 | 85.2 | 4 | 14.8% | ||
| A3 | 12 | 85.7 | 2 | 14.3% | ||
| Dorr | A | 15 | 100 | 0 | 0 | P = 0.11 |
| B | 18 | 85.7 | 3 | 14.3% | ||
| C | 15 | 75 | 5 | 25% | ||