Table 3.
Radiological results classified by the presence of a (reversed) Z-effect.
| Variables | Z-effect* (n = 7) | No Z-effect (n = 73) | p |
|---|---|---|---|
| AO classification [n (%)] | |||
| A1.1 – A1.3 | 2 (29) | 14 (19) | 0.5 |
| A2.1 – A2.3 | 4 (57) | 32 (44) | 0.5 |
| A3.1 – A3.3 | 1 (14) | 27 (37) | 0.2 |
| Superior screw TAD (mm) | 21 (IQR 17) | 26 (IQR 17) | 0.5 |
| Superior screw TADmax (mm) | 26 (IQR 41) | 28 (IQR 15) | 0.9 |
| Superior screw TADdiff (mm) | 6 (IQR 7) | 3 (IQR 5) | 0.2 |
| Inferior screw TAD (mm) | 24 (IQR 14) | 25 (IQR 15) | 0.6 |
| Inferior screw TADmax (mm) | 26 (SD 41) | 28 (SD 15) | 0.4 |
| Inferior screw TADdiff (mm) | 13 (SD 66) | 3 (SD 5) | 0.001 |
| Quality fracture reduction (score 0–2) | 2.0 (IQR 1.0) | 2.0 (IQR 1.0) | 0.8 |
| Angle inferior lag screw (Ax, °) | 9 (SD 8) | 7 (SD 9) | 0.7 |
| Collodiaphyseal angle (AP, °) | 131 (SD 8) | 133 (SD 8) | 0.6 |
| Correct placement inferior lag screw in femoral heada [n (%)] | 4 (57) | 46 (63) | 0.3 |
Note: Data are presented as mean when normally distributed and as median when non-normally distributed.
SD = Standard deviation; IQR = Interquartile range; ASA score = American Society of Anesthesiologists score. TADdiff = Tip Apex Distance difference of TADmax (maximal measured TAD distance over time) minus the TAD (first post-operative measured TAD). AP = anteroposterior view, Ax = axial view.
a
Correct placement established as inferior or centrally placement of the lag screw on the anteroposterior radiograph and central placement on the axial radiographs.
∗
Z-effect or reversed Z-effect.