Dr Simon Locke
On March 8th this year, eight members of the Ultrasound Peer Review group participated in an ultrasound guided injection course using unembalmed cadavers at the University of Tasmania’s clinical school overseen by visiting Doctor Tom Clarke (USA).
Doctor Tom Clarke, founder of MSKUS, is an internationally-recognised musculoskeletal ultrasound practitioner and registered vascular technologist with over 35 years of clinical experience including 20 years of musculoskeletal ultrasound experience, and over 15 years of teaching experience across North America, South America, Europe, and the Asia-Pacific. Dr Clark also holds adjunct professorship positions in the departments of Sports Medicine (Rutgers), Pain Management (Robert Wood Johnson Medical School), and Radiology (Logan University and National University.
Anaesthetists have previously described the educational benefits of unembalmed cadaver injection courses as part of training reviews. Hocking and Mcintyre (2011) reported 98% of course respondents found the training beneficial with comparable imaging and tissue properties to real life. At a 3/12 follow-up, 84% of the attendees considered they had sufficient training and improved confidence to introduce ultrasound into their clinical practice. 87% commenced ultrasound procedures routinely as a consequence of the course.
The workshop was held at the University of Tasmania clinical school in Hobart. It was held in the surgical simulation laboratory over 3 days. David Humphries and the clinical school staff capably organised the course.
The workshop was a remarkable experience. A number of the participants previously attended Tom's courses both in diagnostic ultrasound as well as injection techniques. Most felt uneasy when observing a skilled technician. However, as a learning experience in improving technical skills, it is to be recommended, valued and repeated particularly for the opportunity to practice various injection techniques without risk to a living subject.
The course started with a lesson in injection process. All of us are involved in sport, where posture is an important component of technique. This also applies to injections, generally, necessitating a linear relationship between clinician, patient/target and ultrasound machine. Tom demonstrated how eye dominance adversely affects needle deviation from the target line and target. He demonstrated the necessary steps needed to recognise and dealt with this problem. Eventually the impact of eye dominance decreases. The next step was optimising the various postures adopted during injections. This was a very salient lesson at the beginning of the course.
We revisited normal joint injections; ankles, shoulders, hips and knees. With shoulders, there was a slight change in well-published techniques that improved entry into the glenohumeral joint and minimised cartilage or labral contact. As before, when performed under expert supervision, this proved to be a relatively easy exercise and was repeated a number of times by the participants. Manipulation of the transducer allowed access to the joint and improved as the course progressed. The key to successful ultrasound guided injections is maintaining a close relationship between the transducer and the needle tip. Use of bevel up and down manipulation allowed differences between entry and injection. Simple manipulation or indeed changing the transducer allowed this relationship to be maintained whilst changing the angle of attack of the needle. We used the cosine of the angle and the relationship to the hypotenuse (depth of target) to determine needle length. This simple manipulation of principles allowed the point of entry to be chosen away from the transducer and optimises needle image. We routinely used 70 mm 22G needles.
We revised various topics after each session and before the next session.
Apart from regulation ultrasound guided injections, we were exposed to anatomy demonstrations that assisted injecting technique. We explored various peripheral nerve injections. For example, neuropathic pain post TKA occurs in about 10-20% of cases and can be caused by saphenous and obturator nerve entrapment which can be visualised and blocked at various sites. During one session, different ultrasound settings were explored to optimise the image of the nerve. Generally, the setting changes included frequency, depth, focus and gain.
Buttock pain is common in the clinical practice of many sport and exercise physicians. We visualised SIJs, superior gluteal nerve, obturator's internis, posterior cutaneous nerve of the thigh and its relationship to the ischial tuberosity. These demonstrations provided evidence for the use of ultrasound in clinical practice. Whilst some of the previously mentioned structures are common causes of buttock pain, some are not as common but with simple techniques can be visualised. However, like all skills, practice is important.
The problem at the end of the course was dealing with the volume of information and how to incorporate this into clinical practice. People will take different aspects of the course home with them. Hopefully, during our next meeting at the PRG, we will be able to share these thoughts and revisit the experience so that more useful techniques can be used in our practice.
Personally, the greatest impact was the role of posture, eye dominance and preparation in improving injection technique. This is something that can be repeated in all injections. Patient position is also critical and by raising and lowering the bed improved outcomes can be expected.