## 3 Results
### Effect of Operation of Lower Extremity Edema on the Plantar Pressure Distribution
#### 3.1.1 Standing  
The results show that, in terms of MP value (Figure 5), 6 out of 12 detection points on the left and right feet show significant differences, namely the left foot point L4 (from 395 to 121) and the left foot point L5 (from 278 to 138), right foot point R1 (from 86 to 12), right foot point R4 (from 554 to 147), right foot point R5 (from 1139 to 135) and right foot point R6 (from 1069 to 140). When the data was further analyzed, it could be shown that both the left foot and the right foot had relatively large improvements in the midfoot and hindfoot areas.  
Figure 4: Experiments of standing, walking and riding a bicycle. (**a**) Standing. (**b**) Walking. (**c**) Riding a bicycle.  
What is more special is that the subject's right foot improved more significantly than the left foot. This is because the subject's body is tilted to the right due to the serious edema of the left foot. This can be seen from the fact that the thumb pressure on the right side of the patient is greater than that on the left side. As a result, the sole of the right foot was relatively high before the operation. Because of this, the degree of improvement in plantar pressure after surgery is relatively large. What is more commendable is that if you further compare the MP value of the subject after the operation, we can see that the pressure value of the corresponding point on the left and right feet of the subject after the operation is roughly the same. This result shows that the whole operation is quite successful in terms of the subject's standing movement.  
The following analysis is based on the maximum foot pressure PP. The maximum value represents the maximum value it may produce during the test. This value may be of little significance to people with normal soles. However, for a person with lower extremity edema, this value may cause irreversible damage. The results show that in terms of PP value, the left foot point L4 and point L6 and the right foot point R3 to R6 all show significant improvement (Figure 6). This value again confirms two things. The PP of the midfoot and hindfoot of the first subject is significantly improved due to surgery; the PP on the right of the second subject has a greater degree of improvement than the left.  
Finally, this study used the STD value (Figure 7) to analyze the patient's plantar pressure changes. This value indicates the change in the pressure of the patient within about 1-2 min of standing. In this study we interpret this change as the stability of the patient. The results showed that the STD value of L1 ranges from \(\pm\)12.88 to \(\pm\)1.51, L2 ranges from \(\pm\)14.03 to \(\pm\)0.91, L3 ranges from \(\pm\)41.59 to \(\pm\)7.75, L4 ranges from \(\pm\)75.44 to \(\pm\)5.54, L5 ranges from \(\pm\)50.89 to \(\pm\)3.49 and L6 ranges from +94.47 to \(\pm\)1.92. Obviously, the STD value of each point on the left foot has been significantly improved. Similarly, the STD value of each point on the right foot is also significantly reduced. Based on the above results, regardless of the MP, PP and STD values, postoperative foot pressure and  
Figure 5: Standing MP in the lymphedema patient’s foot before and after surgery. * \(p\)-value < 0.05 indicates that a significant difference exists.  
Figure 6: Standing PP in the lymphedema patient’s foot before and after surgery. * \(p\)-value < 0.05 indicates that a significant difference exists.  
body stability during standing were significantly improved, especially in the midfoot and hindfoot areas.