MUSCULOSKELETAL ULTRASOUND

clinically suspected, it seems only sensible that this level of examination is best done using high spec hospital equipment in the hands of an experienced MSK sonographer, usually a consultant radiologist.

Because there are different levels of skill and experience required to competently examine different structures within the same anatom- ical region it is beyond the scope of this article to give more than a broad brush of the clinical applications of MSKUS. There is however one particularly excellent instructional MSKUS DVD produced by the American Institute of Ultrasound in medicine (AIUM); although the DVD is expensive I would highly recommend it, and if you subscribe to the AIUM for a year, it is half-price ($450). Especially useful are the split-screen live video demonstra- tions and commentaries that can be referred to again and again.

Certainly one absolute pre-requisite for competent MSKUS is a good clear knowledge of peripheral and functional musculoskele- tal anatomy; this acts as the clinician’s ‘road map’ when scanning. When joints are moved around, especially the shoulder, it is easy to lose sight of which structure you are scanning, and in what plane. Pathological changes with tendon tears and fluid can add to the confusion. In addition, care must be taken to ensure that a seemingly cystic structure is not a blood vessel.

Shoulder and upper limb This is typically the first major joint that practitioners interested in performing MSKUS will be encouraged to master. The shoulder joint has several structures accessible to ultrasound and can

FIGURE 2: ULTRASOUND OF THE ROTATOR INTERVAL

When scanning the shoulder, one particularly important view is to scan across the rotator interval (red arrow) where the biceps tendon (BT) passes through the cleft between the supraspinatus tendon (SSP) and the subscapularis tendon (SBPT). Deltoid muscle (DEL) should lie superficial to all these structures. The ultrasound probe/cable position (used to create the scan image on the right) is denoted by blue schematics in the left diagram.

SSP BT SBPT DEL

account for around 70% of all MSKUS scans in hospital radiologi- cal departments (AIUM disc). The examination is also traditional- ly taught in a standard sequence, mainly to get into good scan- ning habits and become acquainted with normal anatomy; this also reduces the risk of missing pathology (see Box 1).

The biceps tendon is an important landmark; if the scanner ever becomes ‘lost’, the biceps tendon is a great reference point. When looked at transversely it normally sits in the bicipital groove, with the transverse ligament securing it in the bicipital groove as it heads

BOX 1: A COMMON PROTOCOL FOR MSKUS OF THE SHOULDER JOINT (MANIPULATION AND MOVEMENT OF THE ARM/SHOULDER DURING THE EXAMINATION ARE HIGHLIGHTED IN ITALICS)

Shoulder neutral and palm upward 1. Transverse (TS) and longitudinal (LS) biceps tendon. 2. Check transverse ligament and that biceps is stable in its groove by scanning in TS as shoulder is move in and out of external rotation

Patient externally rotates shoulder 3. TS of subscapularis 4. LS subscapularis. 5. Dynamic internal/external rotation to look for any sub- scapularis bursa or impingement. Internally rotate shoulder (‘hand in the pocket’ position). If you over-internally rotate with the hand too far up the back, you can loose sight of the front edge of supraspinatus. 6. TS supraspinatus tendon. Get medial to see critical zone, rotator cuff interval and the biceps tendon nudging against anterior edge of supraspinatus. Image the contour of the tendon and a look for smoothness/even-ness of insertion as you slide the probe along in transverse section. Look for sagging, flattening and unevenness of its insertion. Remember the probe follows the curved contour of the shoulder to avoid anisotropy. If the supraspinatus is com- pletely torn, all you may see is the deltoid muscle sitting directly on the humeral head (figure 2b)

7. Swing the probe 90 degrees and examine in LS. Look for tendinopathy or calcification - possibly add in power

22 doppler for neovascularisation

Move hand across chest so shoulder is in adduction/flexion to see teres minor and infraspinatus 8. LS view first 9. TS infraspinatus 10. Look at the posterior gleno-humeral joint for effusion, cyst or labral lesion

11. Examine the acromio-clavicular joint for effusion, osteo- phytes, instability or ganglion both with arm by side and across chest

12. Supraspinatus Impingement Test in dynamic abduction. With the arm by the side, seek coraco-acromial ligament in LS and spin the probe 80-90 degrees and abduct the arm gently +/- 30-40 degrees to see the anterior portion of the supraspinatus sliding under the coraco-acromial ‘tunnel’.

Adding some internal rotation can further uncover impingement of a thickened area of tendon as the subdeltoid bursa can be seen to be ‘squeezed’. 13. Examine the spinoglenoid notch for possible ganglion compressing the suprascapular nerve.

14. Depending on the clinical picture, soft tissues, pectoralis major, sterno-clavicular joint and sterno-costal joints can also be usefully examined with MSKUS.

sportEX medicine 2007;34(Oct):20-26