**Abstract**

The term "pes anserinus tendinobursitis (PATB)" is generally used to describe the inflammatory condition of pes anserinus bursa (PAB). Ultrasound (US) is widely used as a diagnostic and therapeutic tool to improve the assessment and management of joints and soft tissues. We performed the study to prove the accuracy and efficacy of US-guided injections in patients with PATB by comparing blind interventions. Forty-seven patients were randomly assigned to an US-guided and a blind injection group. The patients in the US-guided group were given injections under sonographic visualization. Otherwise, in the blind group, injections were provided in the conventional technique without any sonographic guidance. After the management, the accuracy of the injections was assessed by identifying the injectate location using the US. Treatment efficacy was evaluated using the visual analog scale (VAS) of knee tenderness. The US-guided group showed that the injectates were located at the PAB accurately in all participants, whereas the blind group revealed that the materials were found to be at the bursa side only in 4 out of 22 patients. VAS scores of the US-guided group significantly improved compared to the blind group. In conclusion, US-guided PAB injections are more accurate and efficacious than blind approaches.

**Keywords:** pes anserinus tendinobursitis, bursa injection, ultrasound

## **1. Introduction**

The pes anserinus (PA), which means "Goose foot" in Latin, consists of the conjoined tendon of the sartorius, gracilis, and semitendinosus muscles. It inserts into the proximal anteromedial aspect of the tibia approximately 5 cm distal to the medial tibial joint line. Biomechanically, it provides secondary restraint against valgus forces of the knee joint [1–4]. The PA bursa (PAB) is located deep to the PA tendon and serves to reduce friction between three tendons and the deep structures including the tibia and the medial collateral ligament (MCL). Commonly, it does not communicate with the knee joint space [3].

The first description of the region in literature dates back to 1937. Moschcowitz described knee pain almost exclusively in women who complained of pain when going downstairs or upstairs, or had difficulty in getting up from a chair, or flexing their knees [5]. PA bursitis or tendinitis, or also called PA tendinobursitis (PATB), is usually used to describe the inflammatory condition of the PAB mainly caused by repetitive friction over the bursa or by direct trauma. It can be observed in patients with rheumatoid arthritis, osteoarthritis (OA), and diabetes mellitus. The risk increases in people who are obese or have valgus knee deformity [6–8]. PATB is clinically common in obese female OA patients. The distinction between PA bursitis and tendinitis is difficult because of the proximity of the structures. In addition, its pathology remains unknown and is still controversial. However, the treatment strategy is similar for those conditions [9].

The exact prevalence of PATB is unknown. It has been reported at a wide range of levels, between 2.5 and 70% [10]. Frequently, the incidence tended to be underestimated due to difficulty in diagnosis. In a retrospective review of 509 knee MRIs obtained on 488 patients with suspected "internal derangement" at an orthopedic outpatient clinic, a 2.5% prevalence of PATB was detected [11]. Sometimes, fluid collection in semimembranosus bursa, around the collateral ligament, or meniscal cyst can make the differential diagnosis difficult. Therefore, it was suggested that fluid collection in the PA bursa accompanied by clinical symptoms such as pain in the medial side of the knee was helpful for diagnosis. In a prospective study, a total of 170 knees of 85 patients with OA were assessed with the US, and the incidence of PA bursitis was 20% [12]. They presented that PA bursitis was more common in women and at advanced ages and was observed in one of every symptomatic OA patient.

The clinical diagnosis of PATB is based on symptoms, including pain in the medial aspect of the knee when going downstairs or upstairs, morning pain and rigidity for more than 1 h, sensitivity to compression on the tendon insertion area, and occasional local edema [11]. Resolving the pain after a local anesthetic injection may also be helpful for diagnosis [12]. MRI can be useful in the diagnosis of PATB when swelling, fluid collection associated with the inflammatory process are observed as like most of the soft tissue pathologies. The exam can be a good method to detect and differentiate cystic lesion within and around the knee [13]. However, results of the image often do not allow to identify structures that are responsible for the symptoms of PATB.

### **2. Significance of US-guided injections**

Many studies have researched the accuracy and efficacy of US-guided injections compared to blind (without a guide) techniques. Gilliland et al. [14] presented a systemic review about the efficacy of US-guided intra-articular and periarticular injection compared with anatomic standard injection using palpation/anatomic landmarks in the joints of the knee, shoulder, foot, ankle, wrist, and hand. They concluded that accuracy was improved with the use of US-guided injection and shortterm outcome improvements were found in the US-guided groups. Berkoff et al. [15] reviewed the clinical utility of US-guided intra-articular knee injections in comparison with palpation-guided anatomical injections. The study suggested that US guidance significantly improved the accuracy of injection in the target joint space. The accuracy induced the improvement of clinical outcomes and cost-effectiveness.

PAB injection is usually performed by a blind method in actual clinical settings because the structure locates close to the superficial layer relative to the shoulder or knee joint. Therefore, it has not been sufficiently studied in relation to the ultrasound (US) guidance. Finnoff et al. [10] compared the accuracy of US-guided and unguided PAB injections in 24 cadaveric lower extremities specimens. The accuracy rate was 92% in the US-guided group and 17% in the unguided group. In spite of the superficial location, most unguided PAB injections failed to place the injectate within the bursa, while US-guided injection showed a high degree of accuracy. Because it was a study using cadavers, therapeutic efficacy in clinical conditions

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

could not be identified. The exact pathology of PATB is still not completely known, which has been studied for more than 80 years. Furthermore, the injection location to prove its effect has not been sufficiently investigated.

This study was conducted with the aim of assessing the accuracy of US-guided PAB injections and evaluating the clinical outcomes of the efficacy of injection by comparing them to blind injections. The study also examined whether the location of injectate could suggest the main source of pain.
