Air Bubble Saline Arthrosonography in Imaging Rotator Cuff Tears

Air Bubble Saline Arthrosonography in Imaging Rotator Cuff Tears

By David Martin, MBBS, BMed Sc(Hons), FRACS, FAOrthA; Parminder J. S. Jeer, MBBS, FRCS, FRCS(Tr&Orth); Yegappan Kalairajah, MA, MPhil, MBBChir, FRCS; Mark Falworth, MBBS, FRCS(Eng), FRCS (Tr&Orth); Steven Zadow, MBBS(Hons), FRANZCR; Neil Simmons, MBBS, FRACR
ORTHOPEDICS 2008; 31:140

February 2008

Air bubble saline arthrosonography decreases user dependency and increases accuracy in the identification and characterization of rotator cuff tears.

The accurate identification and characterization of rotator cuff tears is important when planning surgical intervention and determining the prognosis in patients with rotator cuff pathology.^1,2 Imaging modalities used to investigate a suspected rotator cuff tear include plain radiography, magnetic resonance imaging (MRI), and ultrasonography scanning, all of which can be combined with arthrography.

Magnetic resonance imaging and ultrasonography scanning have been reported to be highly accurate in detecting rotator cuff tears.^3-10 Reports comparing ultrasonography scanning and MRI findings with arthrography and surgical findings suggest similar specificity but lower sensitivity of ultrasonography scanning in the detection of full and partial thickness tears.^11,12 These studies demonstrated the possibility of limited accuracy of ultrasonography scanning diagnosis when lower frequency transducers were used, along with high operator dependency.^11,12 However, compared with MRI, ultrasonography scanning is more readily available, more economical, and less time-consuming. Despite these advantages, ultrasonography scanning has not been widely accepted in the orthopedic community, particularly as an office tool in the investigation of rotator cuff pathology.^13,14

This article describes a new method of combining ultrasonography scanning with an air bubble and saline arthrogram to improve the ease of identification and characterization of rotator cuff tears.

Technique

Air bubble arthrosonogram improves the investigator’s ability to recognize and characterize rotator cuff tears. The technique involves shaking 15 mL of saline with 3 to 5 mL of air in a 20-mL syringe to generate numerous air bubbles. The ultrasonography scanning probe is positioned posteriorly over the infraspinatus tendon with the patient facing the monitor. The mixture is then injected into the glenohumeral joint using a 22-gauge, 50-mm–long needle, which is inserted beneath the probe using a standard posterior approach to the shoulder. After retracting the needle, the patient is encouraged to exercise the shoulder for 30 seconds to aid the distribution of the air bubbles and saline. If pain is a limiting factor when performing shoulder movements, the saline can be substituted with a local anesthetic. Standard ultrasonography scanning of the shoulder is then performed.

Improved visualization of the rotator cuff tear is possible due to the air bubble–tissue interface. In rotator cuff tears, the bubbles are seen escaping from the glenohumeral joint. The bubbles that adhere to the tear edge help to characterize the nature and extent of the tear. Partial tears are more easily identified, as the defect is more clearly visualized.

Figure 1: Left shoulder sta Standard ultrasonography scan along the long axis of the supraspinatus tendon. It is not clear from this image as to whether the previous cuff repair is intact. The bursa, humeral head, and trough from previous repair are seen (A). Left shoulder air bubble saline arthrogram demonstrating no significant differences compared with standard ultrasonography. With no fluid or bubbles in the bursa, the integrity of the previous supraspinatus tendon repair is confirmed. The humeral head and trough from previous repair are seen (B). Postgadolinium T1 fat saturated magnetic resonance image of the left shoulder demonstrating a thin and irregular supraspinatus tendon in the presence of a previous repair. No contrast has entered the bursa confirming an intact cuff repair, although there are irregularities on the articular surface of the supraspinatus. The metal artifact, humeral head, and corocoid process are seen (C). Abbreviations: A=metal artifact, B=bursa, CP=corocoid process, HH=humeral head, SS=supraspinatus tendon, and T=trough.

The resulting images of this technique, performed on the left and right shoulders of a 45-year-old man with previous cuff repairs, are presented in Figures 1 and 2. Four years after the cuff repairs, the patient reported discomfort and weakness in both shoulders. Standard ultrasonography scanning was performed (Figures 1A, 2A). Due to the difficulty in a definitive diagnosis, an air bubble saline arthrogram was performed in each case (Figures 1B, 2B). Magnetic resonance imaging was performed to confirm the ultrasonography findings (Figures 1C, 2C, 2D). An Acuson sequoia ultrasound machine with a 15- to 8-MHz–wide linear array (Acuson, Mountain View, California) was used to create these images.

Discussion

A diagnostic test is judged by its accuracy, sensitivity, and specificity. This modified technique improves upon conventional ultrasonography scanning in fulfilling these criteria.

This technique has been helpful in the diagnosis of rotator cuff pathology while also being simple, safe, and without complications. It has the advantages of arthrography without the possible complications linked to contrast media.¹⁵ Furthermore, it is quicker, more economical, and more accessible than MRI and sensitive enough to aid in the diagnosis of rotator cuff pathology. The ability to characterize tear size, thickness, and edge morphology is also improved on. It is particularly useful as an adjunct to ultrasonography scanning if there is a thickened subacromial bursa, which can make the diagnosis of a rotator cuff tear more difficult. The echogenic shadowing produced around the cuff tear is also helpful if a clear ultrasound image is not produced due to prior surgery, or if the anatomy is too distorted to confidently diagnose using standard ultrasound techniques. Air bubble saline arthrosonography can be used in these cases rather than MRI, which is more expensive and may not be as readily accessible.

Figure 2: Right shoulder standard ultrasonography scan along the long axis of the supraspinatus tendon at its anterior aspect. It is difficult to define the difference between the tendon and bursa, and the integrity of the previous cuff repair is not conclusive. The humeral head, cartilage, and trough from previous repair are seen (A). Right shoulder air bubble saline arthrogram demonstrating distension of the bursa and a more defined edge to the torn supraspinatus tendon. This confirms a full thickness tear of the previous repair. The humeral head, cartilage, and trough from previous repair are seen (B). Postgadolinium T1 fat saturated magnetic resonance image of the right shoulder demonstrating a more posterior aspect of the supraspinatus tendon which is irregular on its articular surface. Contrast in the bursal space suggests a torn cuff repair. The humeral head is seen (C). Postgadolinium T1 fat saturated magnetic resonance image of the right shoulder demonstrating contrast in the bursal space, confirming a full thickness tear of the supraspinatus tendon. The long head biceps, humeral head, and corocoid process are seen (D). Abbreviations: B=bursa, C=cartilage, CP=corocoid process, FTT=full thickness tear, HH=humeral head, LHB=long head biceps, SS=supraspinatus tendon, and T=trough.

Previous concerns with ultrasonography scanning were based on its operator and equipment dependency. This dependence should be reduced by the greater ease of interpretation of the ultrasonography images using the air bubble saline arthrosonogram technique. Furthermore, this technique should allow orthopedic surgeons performing office-based ultrasonography scanning greater diagnostic accuracy, thereby aiding in the management of rotator cuff disease.

We acknowledge that validation of the technique with a prospective study correlating ultrasonography scanning appearance with operative findings at surgery and MRI are needed.

References

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Authors

Drs Martin, Jeer, Kalairajah, and Falworth are from SPORTSMED SA; and Drs Zadow and Simmons are from Jones and Partners, Adelaide, Australia.

Drs Martin, Jeer, Kalairajah, Falworth, Zadow, and Simmons have no relevant financial relationships to disclose.

Correspondence should be addressed to: Mark Falworth, MBBS, FRCS(Eng), FRCS (Tr&Orth), SPORTSMED SA, 32 Payneham Rd, Stepney Adelaide, SA 5069, Australia.