Injection therapy around the distal biceps tendon can be performed in patients with a partial biceps tendon tear, bicipitoradial bursitis or distal biceps tendinopathy. Injection therapy with platelet-rich plasma or glucocorticoids around the distal biceps tendon and in the bicipitoradial bursa is challenging because of the lack of clearly palpable landmarks; complex distal biceps anatomy; and proximity of the brachial artery, median nerve, and posterior interosseous nerve [1-7]. The bicipitoradial bursa is located between the distal biceps tendon and the anterior part of the proximal radius. The bicipitoradial bursa surrounds the biceps tendon in supination. In pronation, the radial tuberosity compresses the bicipitoradial bursa between the biceps tendon and the radial cortex [5-9].

There are different injection techniques with different approaches available for infiltration around the biceps tendon [1]. Some perform the injection manually without ultrasound guidance; others use ultrasound guidance to determine the location of the tip of the needle. The preferred location of injection is in the bicipitoradial bursa. Establishing accuracy of manually injections would improve the clinical results of injection therapy.

The primary aim of this study was to determine the accuracy of manually performed injections of the biceps tendon without radiological guidance by upper extremity surgeons. We hypothesized that manually performed injections are inaccurate and that the majority of injections (>50%) would not be located in the bicipitoradial bursa or near the biceps tendon.

This prospective study was performed during an arthroscopy and arthroplasty cadaveric course of the elbow at the University Medical Centre in Utrecht, The Netherlands. No Institutional Review Board approval is needed for cadaveric studies performed at our institution. These specimens were derived from bodies that entered the Department of Anatomy through a donation program. Written consent was obtained from these persons during life that allowed for the use of their entire bodies for educational and research purposes.

Each participant performed one perforation per infiltration and all injected 2 mL of acrylic dye in both techniques. A total of 19 injections (10 [53%] using the anterior infiltration technique and 9 [47%] using the lateral infiltration technique) were performed in 10 cadaveric elbows. Of the 19 performed infiltrations, 15 injections (79%) were located during dissection in or near the biceps tendon. The dye was not located near the biceps tendon in the remaining four injections (21%). Of these four injections, three were anteriorly injected (75%) and one was laterally injected (25%). Three out of the 15 injections (20%) were located (totally or partially) on the radius near the bicipitoradial bursa. Of these injections, one was given anterior (33%) and two lateral (67%). The remaining 12 injections (80%) were located (totally or partially) in or near the biceps tendon. We found “a lot” of dye in 13 (87%) of these injections. We found “a little” dye in the other two (13%), one of which was injected anteriorly (50%) and one laterally (50%) (Tables 1 and 2).

We hypothesized that manually performed injections of the biceps tendon without ultrasound guidance would be inaccurate and that the majority of the injections would not be located in the bicipitoradial bursa or near the biceps tendon. The most important finding of this study was that manually performed injections of the biceps tendon lack accuracy. Only three of the nineteen injections were located (totally or partially) near the bicipitoradial bursa.

Our study had some limitations. First, infiltration around the distal biceps tendon and in the bicipitoradial bursa is challenging because of the lack of clearly palpable anatomical landmarks. Location of these anatomical landmarks is even more difficult in cadaveric arms. When infiltrating a living patient, the patient can locate the pain. This may facilitate accurate infiltration. The biomechanical properties of tissue are different in cadavers as compared to living subjects. However, the fresh frozen cadavers used in this study accurately resembled living tissue [10]. Second, during the study we mainly focused on the location of the dye. We did not assess the structures passed by the needle; therefore, the needle may have caused neurovascular injuries. Leaving the needle in place and dissecting the pathway might have helped assess this. Third, the acrylic dye had to set for 5–10 minutes, but some participants started their dissection too early due to other course activities. This may explain the smaller amounts of dye found. Fourth, bias may have been introduced by having the participants dissect and assess their own injected elbows. Fifth, the sample size of the cadavers and participants in our study was small and did not allow for stratification based on experience or skill. However, a larger sample size would probably not change our conclusions. Further, none of the participants had previously performed an infiltration of the distal biceps tendon without radiological guidance. Most colleagues ask a radiologist to perform these infiltrations using ultrasound guidance in daily practice.

Previous studies have shown that infiltration in the bicipitoradial bursa with ultrasound guidance is difficult. There are several viable options described for infiltration with ultrasound guidance. Sellon et al. [1] found a high success rate for sonographically guided peritendinous and intratendinous infiltration of the distal biceps tendon through multiple approaches. All of their peritendinous injections were successful, and 94% of their intratendinous injections were successful. Mautner et al. [4] demonstrated with their case study that an ultrasound-guided, posterior, in-plane approach for distal biceps tendon infiltration was safe and effective. Chang et al. [11] demonstrated that an ultrasound-guided infiltration of the bicipitoradial bursa for bicipitoradial bursitis was safe and successful. In comparison, for the infiltration of the shoulder girdle, Aly et al. [12] found an improved accuracy for ultrasound-guided injections compared to landmark-guided injections.

In daily practice we recommend infiltration of the bicipitoradial bursa using ultrasound guidance. This technique allows for a more accurate injection and more optimal treatment of a partial biceps tendon tear, bicipitoradial bursitis or tendinopathy. Further studies on infiltrations of the distal biceps tendon in living human subjects are needed. These should focus on the clinical efficacy and accuracy of ultrasound-guided and manually performed injections. Infiltration of the bicipitoradial bursa without ultrasound guidance lacks accuracy. For more accurate treatment of a partial biceps tendon tear, bicipitoradial bursitis or tendinopathy, we recommend infiltration of the bicipitoradial bursa using ultrasound guidance. Further studies on infiltrations of the distal biceps tendon in human subjects, particularly a study that directly compares manual versus ultrasound-guided infiltrations, will be useful.