Ultrasound imaging has become a valuable tool in guiding injections for musculoskeletal disorders due to its ability to provide high-resolution images of soft tissues without subjecting patients to radiation exposure [1]. However, profi ciency in injection skills requires extensive practice, which can be a challenge when the practice is usually conducted on patients considering the risks of collateral neurovascular injuries. To address this, perfecting injection techniques on cadavers is an ideal solution. The Taiwan Pain Society has collaborated with the Tzu Chi medical center and the Tzu Chi University to conduct ultrasound-guided cadaveric injection education workshops. Donors selflessly offered the bodies to the Tzu Chi University Silent Mentor Program and were preserved in whole with deep freezing for storage at –30°C. The bodies were thawed starting 6 days before the program for a 4-day combination of different workshops. The present pain management workshop that we reported was on the fi rst and second days of this series of workshops. Herein, we reported in a brief communications to format the essential factors for conducting a successful cadaveric injection workshop (Table 1).

Firstly, fundamental knowledge of the sonoanatomy of the intended area is necessary before trainees practice injection on cadavers (Figure 1). In case of deep freezing preserved cadavers, one has to be aware that certain structures such as muscles might have been destroyed in the process of freezing and thawing. This makes it challenging to identify the structure precisely. In this regard, the position of the target in relation to adjacent structures serves as the crucial guidance. A didactic course [2] that elaborates on sonoanatomy and demonstrates scanning techniques on live models can signifi cantly improve the effi cacy of identifying the correct target when trainees practice on cadavers.

Secondly, the basic concept of ultrasound-guided injection should be clearly explained before handson cadaveric injection. Terminology such as short-axis and long-axis should be clarifi ed and exemplifi ed. Trainees can try fi rst to master the skills of in-plane and out-of-plane on low-cost phantoms. Tutors of the cadaveric course are suggested to focus on demonstrating the best needle entry path and red fl ag structures, such as the vertebral artery during C7 nerve root injection [3].

Thirdly, unlike most of the musculoskeletal ultrasound training courses that focus on delineating sonoanatomy, tutors are advised to prepare a list of structures for practicing the injection. The selection of structures can be based on their clinical relevance and risk of collateral neurovascular injuries. For example, ultrasound-guided subdeltoid bursa injection can effectively manage rotator cuff tendinopathy [4], a common cause of shoulder pain. Therefore, identifying the subdeltoid bursa with ultrasound and then proceeding with injections should be prioritized while tutors explain the injection techniques over the shoulder joint. Conversely, when complex regional pain syndrome is not prevalent, conservative treatment usually results in limited relief. In this case, ultrasound-guided satellite ganglion injection might provide better symptom relief. One should be careful to identify neurovascular structures, such as the vagus nerve, common carotid artery, and vertebral artery to prevent collateral damage. Tutors should guide the trainee to practice planning the injection needle path to prevent injury to the aforementioned neurovascular structures.

Fourthly, to inject the cadavers on the surgery table is a greater challenge than real patients. For instance, administering an injection to the distal attachment of the anterior cruciate ligament requires the knee to be flexed at least 90° [5], which requires a tutor to assign other trainees to assist in stabilizing the flexed knee. Similarly, performing a suprascapular nerve block over the suprascapular fossa is typically done with the patient seated, which is not possible with a soft cadaver preserved with deep freezing [4]. Instead, one can position the cadaver in prone position as this provides better visualization of the floor of the suprascapular fossa when doing the ultrasonography with a posterior approach.

Fifthly, when trainees practice the injection of deep tissues, tutors should be mindful of any unmelted icicles due to insufficient thawing, which can be mistaken for a bony cortex (Figure 2). In such situation, the tutor should guide the trainee to identify adjacent nonfrozen structures to determine the correct location of the target. For instance, when trainees inject the piriformis muscle [6], icicles might be present on top of the greater sciatic notch to obstruct the visualization of the muscle. In this case, the inferior sacroiliac joint can be used as a reference point to predict the location of the piriformis muscle. Warm saline can then be injected into the estimated site of the piriformis muscle to melt the icicles before trainees practice the injection.

Sixthly, in the process of practicing injections on donated body, it is crucial to approach the task with respect and professionalism. How we perform during these training exercises reflects our approach on real patients. A careless attitude towards the donated body may suggest a lack of professionalism in our approach in treating real patients and may inadvertently increase the risk of collateral neurovascular injury. By treating the selflessly offered body with the same level of carefulness and attention as real patients, we advance our skills and improve our ability to identify optimal needle entry paths and select the best injectable distribution method. One should be thankful to the selfless offering of the body donors. They are the silent teachers of the workshop. Their altruism and generosity has established a virtuous cycle in the skill development and maturation of pain physicians [7]. This ultimately enables us to confidently alleviate the pain in our patients to the best of our abilities.

Figure 1. Demonstrating the Sonoanatomy of the Region Intended for Injection

An image of the workshop with a tutor elaborating on the sonoanatomy of the region intended for injection.

Figure 2. Pointing to the Phenomenon of Icicles Influencing the Injection

An image of the workshop showing that the tutor is pointing to the phenomenon of icicles (arrow) blocking the visualization of the target structure.

The authors wish to thank the faculty and staff of the Department of Anatomy, the Medical Simulation Center (MSC), and the secretariat of Tzu Chi University (TCU); Tzu Chi volunteers; and dharma masters of the Jing Si Abode for their assistance and support in running the silent mentor program (SMP).

Each author certifies that he or she has no commercial associations.