**3.4 Injection material**

The injection material was a mixture of 20 mg of triamcinolone acetonide and 1 mL of 1% lidocaine. It was injected at the maximal tender point in the PAB area

### **Figure 2.**

*US-guided injection, the transducer was positioned in a longitudinal orientation relative to the anterior fibers of the medial collateral ligament, with an oblique transverse orientation relative to the pes anserinus.*

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

### **Figure 3.**

*US-guided injection, longitudinal ultrasound image of a needle (arrowhead) in the pes anserinus bursa (asterisk) between the medial collateral ligament (MCL) and the pes anserinus (PA) tendon.*

under US guidance and blind method each. After the PA injections, to identify the location of the material, sonographic scanning was performed in both groups.

### **3.5 Assessment**

After the management, the accuracy of the injections was assessed by identifying the injectate location using the US. The injectate location was evaluated by a second operator who was unaware of the previous procedure with more than 8 years of musculoskeletal US experience in diagnosis and management.

Treatment efficacy to the injection was assessed with a pain visual analog scale (VAS) of knee tenderness. The patients were asked to check the degree of pain intensity ranging from 0 (the absence of pain) to 10 (the worst pain ever). Because all the participants in this study had degenerative arthritis of the knees, it was important to distinguish between articular pain and bursal pain. If the patients described it as simply knee pain, the distinction could be confusing. Therefore, the VAS scores were measured while the constant force was applied to the tender point of PA by an examiner with a pressure algometer (FPK-5®Wagner Instruments, USA). This measurement was performed before 1 week and 4 weeks after the injection.

We did not provide any drugs which had the analgesic effect, including nonsteroidal anti-inflammatory drugs that could mask the pain symptoms of the participants. All patients were informed about discomforts after injection. To avoid possible tendon tear or rupture, the patients were advised to rest for at least 2–3 days with the application of ice 3 times every day. Also, they were taught not to do jumping, squatting, kneeling, and bending of the knee for 3 weeks. About 4 weeks after the procedures, complications that had occurred were assessed by individual interviews.

The data were analyzed by using Windows SPSS 18.0 software. To evaluate the outcome measurements before and after treatment in each group, the Wilcoxon signed-rank test was used. Statistical processing was conducted with the Mann-Whitney *U* test for comparison between the two groups. A statistical significance level was set at p < 0.05.
