Fig. 2

The distribution of screws in three clusters based on extraction torque by Twostep Cluster. By using Twostep Cluster, the distribution of extraction torque of pedicle screws showed two prominent peaks and one valley
The distribution of screws in three clusters based on extraction torque by Twostep Cluster. By using Twostep Cluster, the distribution of extraction torque of pedicle screws showed two prominent peaks and one valley