**4. Results**

Forty-seven patients diagnosed with PATB and knee OA were finally recruited. The US-guided injection group included 25 patients with a mean age of 65.36 ± 7.12 years (two men and 23 women). The blind injection group included 22 patients with a mean age of 63.40 ± 6.20 years (two men and 20 women). There were no significant differences in general characteristics including knee OA K-L grade, and baseline VAS scores between the two groups (**Table 1**).

In the US-guided injection group, changes of the VAS for PA tenderness showed that pain reduced significantly from 6.82 ± 1.45 at baseline to 2.28 ± 1.08 1 week after the injection and 3.27 ± 0.94 4 weeks after the injection (p < 0.05) (**Table 2**). In the blind injection group, changes of the VAS also revealed that pain reduced statistically from 6.45 ± 1.12 at baseline to 3.95 ± 1.23 1 week after the injection and 4.60 ± 0.95 4 weeks after the injection (p < 0.05) (**Table 2**).

**Table 3** shows the comparison between the two groups in changes of the VAS score for PA tenderness. The US-guided injection group showed that pain reduced significantly greater than the blind group with regard to ΔVAS scores at 1 week after injection (4.54 ± 0.98 vs. 2.50 ± 1.03) and 4 weeks after injection (3.55 ± 1.14 vs. 1.85 ± 0.84).

After the PAB injections, the injectates were found to be accurate in the PAB, between the PA tendon and the tibia or the MCL, in all 25 subjects in the US-guided injection group (**Figure 4**). On the other hand, in the blind injection group the materials were found to be located in the PAB in only four of 22 subjects, deep to the MCL in two, and superficial to the PA tendon in 16 patients (**Figure 5**). Most injectates were administered outside the PA bursa.


*Values are presented as mean ± standard deviation.*

*US = ultrasound; OA = osteoarthritis; K-L grade = Kellgren-Lawrence grade; VAS = visual analog scale; PA = pes anserinus.*

### **Table 1.**

*Baseline characteristics of both groups.*


*Values are presented as mean ± standard deviation.*

*VAS = visual analog scale; PA = pes anserinus; US = ultrasound.*

### **Table 2.**

*Changes of VAS of PA tenderness comparing baseline.*

*<sup>\*</sup>p < 0.05 by Wilcoxon signed-rank test.*

*Accuracy and Efficacy of Ultrasound-Guided Pes Anserinus Bursa Injection DOI: http://dx.doi.org/10.5772/intechopen.100344*

Intra-tendon injection was not performed on any of the participants in either group. Complications were not reported after the intervention in both groups.


*Values are presented as mean ± standard deviation. VAS = visual analog scale; US = ultrasound. \*p < 0.05 by Mann-Whitney U test.*

### **Table 3.**

*Changes of VAS of PA tenderness between two groups.*

### **Figure 4.**

*Ultrasound image of the injectate location after injection; intra-pes anserinus bursa area.*

### **Figure 5.**

*Ultrasound image of the injectate location after injection; extra-pes anserinus bursa area, the injection was superficial to the tendon.*
