# Effects of Achilles Tendon Moment Arm Length on Insertional Achilles Tendonopathy
## 3 Results  
The average height of subjects in the healthy group was \(163\pm 7.4\) cm, with average body weight and BMI of \(64.5\pm 12.1\) kg and \(24.3\pm 4.8\) kg/m\({}^{2}\), respectively. The average height of subjects in the IAT groups was \(163.6\pm 13.3\) cm, with average body weight and BMI of \(73.5\pm 11.0\) kg and \(27.7\pm 4.5\) kg/m\({}^{2}\), respectively. Thus, there was no significant difference between the groups for these items (Table 1).  
The AOFAS scale and VAS improved in all cases (AOFAS scale: Preoperative averaged 71.7, postoperative averaged 92.3; VAS: Preoperative averaged 5.0, postoperative averaged 0.83).  
MRI assessment after surgery for IAT revealed Achilles tendon insertion running from the proximal knotless anchor insert to the distal knotless anchor insert via the suture bridge technique in all cases (Figure 6). Also, MRI findings showed the disappearance of abnormal signals in the Achilles tendon in all cases.  
There was no significant difference in the \(\alpha\) angle between the control and IAT groups. The ratio of MA length/foot length was \(0.30\pm 0.9\times 10^{-3}\), in the control group, \(0.31\pm 1.0\times 10^{-2}\), in the IAT group preoperatively, and \(0.27\pm 0.2\times 10^{-1}\) in the IAT group postoperatively, showing significant differences between these groups (\(p<0.05\)). The force applied to the Achilles tendon was \(148.5\pm 24.9\) kg in the control group, \(166.2\pm 23.0\) kg in the IAT group preoperatively, and \(200.8\pm 25.4\) kg in the IAT group postoperatively. Despite no significant difference in the force between the control and preoperative IAT groups, a significantly higher force to the Achilles tendon was observed in the IAT group postoperatively, compared to the other groups (\(p<0.05\)) (Figure 7).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **IAT** & **Control** & \(p\)**Value** \\ \hline n & 10 feet (8 people) & 15 feet (15 people) & \\ Sex & Male: 4 Female: 4 & Male: 8 Female: 7 & \\ Age, y & \(55.5\pm 14.4\) & \(37.4\pm 16.2\) & \\ Height, cm & \(164\pm 13.3\) & \(163\pm 7.44\) & \(>\)0.05 \\ Body weight, kg & \(73.5\pm 11.0\) & \(64.5\pm 12.1\) & \(>\)0.05 \\ BMI, kg/m\({}^{2}\) & \(27.7\pm 4.58\) & \(24.3\pm 4.83\) & \(>\)0.05 \\ \hline \hline \end{tabular} Abbreviations: IAT, insertional Achilles tendinopathy. BMI, body mass index. Values are given as mean \(\pm\) standard deviation (SD).  
\end{table}
Table 1: Patient Characteristics.  
Figure 6: The MRI images of T2-weighted images of the same patient. \(\leftrightarrow\): Length of Achilles tendon insertion. (**A**): Pre-operation of the Achilles tendon insertion. (**B**): Post-operation of the Achilles tendon insertion. We can see the postoperative Achilles tendon insertion presence from the proximal knotless anchor insert to the distal knotless anchor insert.  
Figure 7: Radiographic Measurement. **(A)**: Comparison of the \(\alpha\) angle between the control and pre-operative IAT groups. **(B)**: Comparison of the ratio of MA length/foot length between the control group, the preoperative IAT group, and the postoperative IAT group, showing significant differences between these groups (\(p<0.05\)). **(C)**: Comparison of the force applied to the Achilles tendon between the control group, the preoperative IAT group, and the postoperative IAT group, showing that a significantly higher force to the Achilles tendon was observed in the IAT group postoperatively, compared to the other groups (\(p<0.05\)). Values are given as mean \(\pm\) SD.