DIAGNOSIS

THE CLINICAL APPLICATIONS OF MUSCULOSKELETAL

ULTRASOUND IN PRIMARY CARE

In part one of this article, published in the July issue of sportEX medicine, we provided an overview of the training, equipment, resources and support networks normally required to set up and sustain an introductory musculoskeletal ultrasound practice (MSKUS) - and importantly, one that will stand up to clinical governance. This next article is divided into two parts, one of which is published in this issue and one which will appear in the January 2008 issue The articles cover the most common, practical clinical applications that are associated with MSKUS. Detailed discussion of individual areas and techniques is beyond the scope of this article but can be found in textbooks (1-4) and one or two useful journal seminars (5,6).

By Dr Duncan Robertson MBChB, MRCGP, MSc(SEM), PGCMskUltsnd, FFSEM(UK)

INTRODUCTION Clinical MSKUS can usefully be broken down into three main groups: 1. Diagnostic 2. Interventional 3. Biofeedback

Often the first two of these will occur together in the same clinic (an example of the increasing popularity of the ‘one-stop- shop’ approach to combining imaging with treatment, see figure 1). In cutting-edge physical therapy clinics, all three applications may be employed together.

FIGURE 1: AN EXAMPLE OF THE USE OF MSKUS IN A ‘ONE-STOP-SHOP’ TYPE CLINIC

FIGURE 1. AN EXAMPLE OF THE USE OF MSKUS IN A ‘ONE- STOP-SHOP’ TYPE CLINIC

1a UArt UN PIS 1b

An example of how MSKUS can support a ‘one-stop-shop’ approach where appropriate. Here we see in figure 1a (cross-section) and 1b (longitudinal), a ganglion cyst (pink outline) in Guyon’s canal causing entrapment symptoms in the ulnar nerve (UN) at the wrist.

The pisi-

form bone (PIS) is an impor- tant landmark.

Image 1c NT 1c

captures a moment near the end of an ultrasound-guided injection of steroid into the cyst – the end of the needle (NT) can be clearly seen in the ganglion. Echogenic injection

material has replaced the dark low-echo signal of the ganglion, as seen in 1b. The patient had avoided referral for possible surgery, did not require further investigations in this case, and was reviewed some 4 weeks later, when an all his symptoms had resolved. He was warned of the risk of recurrence.

www.sportex.net

As emphasised in part one, MSKUS is skill that can only be learned properly by repeated practical ‘hands-on’ courses and follow-up clinical sessions with experienced tutors and mentors. Normal anatomy of some regions can be learned fairly readily; much more challenging is the correct interpretation of abnormal findings, especially subtle lesions.

It is well known that even in the best hands, no one is perfect at diagnostic MSKUS imaging. MSKUS is dependent on the combined effect of operator skill plus the imaging power of the scanner itself; hence everyone, whether advanced expert or novice, has to work on their own levels of false positives and false negatives. In this respect however, because of their invariably wider knowledge of the anatomy and biomechanics of sports injuries, the MSKUS ‘sonographer-clinician’ can have a slight advantage over purely ‘diagnostic MSK sonographers’ (usually radiologists or specialist hospital-based sonographers). Nevertheless, I take care to stress the ‘can’ in the above sentence, as there is always the danger of inexperienced MSK sonographers trying too hard to ‘make the scan fit the clinical evaluation’, and thus possibly misinterpreting a true negative scan, changing it into a false positive. Double reporting (7) and long term mentoring help to reduce the influence of such outcomes.

1. DIAGNOSTIC MSKUS The use of MSKUS is increasingly being accessed by the whole spectrum of other non-radiologist musculoskeletal practitioners including specialist GPs (GPwSI), sports physicians, physiothera- pists, chiropractors and osteopaths. The areas of the body exam- ined will very much depend on the clinician’s own interest - and in some cases (such as say a shoulder surgeon or a podiatrist), the use of office MSKUS might be exclusive to one joint or region. This article will concentrate on shoulder, knee/leg and foot/ankle. Other areas are briefly covered under ‘advanced MSKUS’.

Although the groin, hip and nerves are generally considered ‘advanced’ in terms of MSKUS, it is difficult to simply categorise specific anatomical zones according to their ‘scan difficulty factor’. For example, in the shoulder region, it is much easier to identify a healthy biceps tendon than it is to pick-up a suprascapular ganglion compressing the suprascapular nerve in the spinoglenoid notch on an ultrasound scan; if the latter is

21