UTILIZATION OF SONOGRAPHY AND A STRESS DEVICE IN THE ASSESSMENT OF PARTIAL TEARS OF THE ULNAR COLLATERAL LIGAMENT IN THROWERS

Abstract

The non-invasive assessment of medial elbow pain in throwers can be challenging. Valgus stress transmitted to the elbow during the late cocking and acceleration phases of the throwing motion can result in injury to the medial ligamentous structures of the elbow, bony surfaces, and common tendon of the forearm flexors. The utilization of musculoskeletal (MSK) ultrasound in combination with the Telos Stress Device (TSD) (Austin & Associates Fallston, MD) can be an alternate quick assessment when radiography is not be available.

INTRODUCTION

The non-invasive assessment of medial elbow pain in throwers can be challenging. Valgus stress transmitted to the elbow during the late cocking and acceleration phases of the throwing motion can result in injury to the medial ligamentous structures of the elbow, bony structures, and other soft tissues including the common flexor tendon and ulnar nerve.^1,2

Baseball players and other overhead throwing athletes can experience vague pain as well as clinically undetectable joint laxity along the medial aspect of the elbow. As the injury progresses, a tear of the ulnar collateral ligament (UCL) will manifest itself as reduced velocity control evident during pitching or throwing.³

Physical examination frequently includes palpation, valgus stress testing, and grip strength testing. When positive, these examinations may be suggestive of but not definitive of a UCL tear. Incomplete tears are often tender upon palpation, but may not demonstrate significant distraction or gapping on valgus stress testing. Stress radiography, Magnetic Resonance Imaging (MRI) and Computer Tomography Arthrography (CTA) remain the gold standard imaging tools for evaluating medial elbow pain and instability.⁴ Timmerman et al, prospectively studied twenty-five baseball players with medial elbow pain and found that each of these diagnostic tools were accurate in identifying both complete and partial undersurface UCL tears.⁴

Musculoskeletal (MSK) ultrasound imaging has emerged as an additional diagnostic tool than can be used to assess medial elbow pain and laxity in baseball players.^6–10 Sasaki et al (2002) was one of the first groups to utilize this form of imaging when they assessed medial elbow instability in baseball players aged 19 to 24 years.⁶ The authors were able to detect significant medial elbow joint gapping of the throwing arm, as well as structural changes to the visualized tissue. These authors' technique involved a gravity valgus stress applied when the elbow was placed at 90 degrees of flexion.

The anterior bundle of the UCL is the major dynamic restraint resisting valgus stress of the elbow during the throwing motion. The anterior bundle of the UCL is commonly injured in throwers⁷ and diagnosis of UCL tears is often difficult, requiring several imaging modalities to assist in confirming the diagnosis. Nazarian et al (2003) used dynamic MSK to reveal abnormalities of the anterior band of the UCL in asymptomatic major league baseball players.⁷ They found that dynamic MSK ultrasound provided a rapid option for evaluating the UCL in professional baseball pitchers. In pitching arms, the anterior band is thicker and more likely to have hypoechoic foci and/or calcifications, and demonstrates more laxity with valgus stress. Harada et al⁸ assessed one hundred and fifty youth baseball players and found that ultrasonography proved effective in detecting medial epicondylar fragmentation, ulnar collateral injuries, and osteochondritis dissecans of the capitellum among young players before they became symptomatic.

DESCRIPTION OF THE DEVICE

Authors have utilized a stress radiography device in order to objectively evaluate medial collateral ligament laxity in throwing athletes. Rijke et al.⁵ concluded that stress radiography of the UCL with the use of the Telos GA–II E Stress Device (TSD) (Austin & Associates Fallston, MD) enabled accurate diagnosis of large tears and elucidated the distinction between these tears and small tears. Ellenbecker et al¹ utilized stress radiography performed using the TSD to examine the elbow of forty uninjured professional baseball pitchers. They used the TSD to determine differences in medial ligament laxity between the players' dominant and non-dominant arms. In both these studies employing the TSD, stress radiography proved a non-invasive technique to assess medial elbow joint laxity.^1,5 The TSD, when used in conjunction with ultrasound imaging, has been found valuable for quick assessment of medial elbow pain in the throwing athlete.⁸

The TSD is used to apply objectively quantifiable stress examinations of the ankle, knee, elbow, and shoulder. This device allows the operator to provide a defined amount of pressure or force to the joint during testing by observing the force on an illuminated LED readout.

MSK ultrasound provides real time soft tissue images using reflected sound waves. This device is both non-invasive and negates the need for ionizing radiation as is required during plain radiography. A 10-12 MHz linear array transducer is most commonly used. The combination of the TSD and MSK ultrasound offers a potential tool for evaluation of the UCL in the clinic.⁹

DESCRIPITION OF THE TELOS –ULTRASOUND PROCOTOL

The patient is seated perpendicular to the device. The arm is placed in the device with the elbow flexed to 25°. The upper arm is placed in external □rotation at approximalely 65° of abduction.

The patient's wrist is supinated and secured between two roller bars. The fingers and thumb grasp the third roller bar The ulnar aspect of the distal forearm is locked against one of the upright counter bearing bars.

A counter force is applied to the radial side of elbow by a screw- threaded device with a diode digital light-measuring device that illuminates the reading of the applied pressure. Before adding stress, an initial sonogram is taken to provide a baseline. The screw shaft device is then used to apply a valgus force. Sequential sonograms are then taken at 10 and 15 kilo-pascal units of force (measured by the diode digital light-measuring device).

The ultrasound transducer is placed longitudinally to forearm and proximally over medial epicondyle. Note that the transducer is parallel with the forearm. This provides proper coronal imaging over medial elbow demonstrating the anterior band of the UCL, common forearm flexors tendon, medial epicondyle (ME), trochlea (T), and ulna (U).

The location of the common flexor tendon origin is identifiable on the medial epicondyle. Distal and deep to the common flexor tendon origin, is the triangular shape of the UCL that can be viewed; (ME) the medial epicondyle; (T) the trochlea; and (U) the ulna.

Constant and progressively graded forces applied to the medial structures allows for examination of regions of UCL partial disruption that may otherwise have been overlooked. The arrow demonstrates a small hypoechoic area in the proximal ligament while the arrowheads illustrate mild widening of the elbow joint compatible with ligamentous injury.

Measurements can be taken at the ulnohumeral joint to assess amount of joint space widening within the joint. Comparison studies of both elbows must be taken. Studies using the TSD during stress radiographs have reported findings of gap joint opening greater that 0.2mm to be suggestive of a partial tear.⁵

DISCUSSION

The superficial location of the UCL of the elbow makes this structure well suited for ultrasound evaluation. Ultrasonography can be used to assess both the integrity of the ligament and the widening of the medial joint space when valgus force is applied.^6–9

The key to a successful exam is a well-positioned transducer on a comfortably seated patient. According to Nazarian et al.⁷, the medial epicondyle and the coronoid process serve as excellent bony acoustic landmarks that enable MSK ultrasound the capability of viewing the UCL. Careful attention must be paid to establish the proper angle for transducer placement. The transducer should be perpendicular to the ligament in order to avoid anisotropy. Anisotropy is defined as a variance in the echogenicity of the scan as a result of a transducer being placed greater or lesser than 90 degrees perpendicular to the structure being examined, thereby producing an artifact.¹⁰

CONCLUSION

Due to rapidly evolving technology, MSK ultrasound as well as the stress device can allow direct visualization of soft tissue structures without exposing an athlete to undue radiation, thus making it an effective and safe assessment tool. When used at the elbow coupled with the TSD, sonographic changes such as excessive asymmetric joint widening, ligamentous thickening, hypoechoic defects, and ligament calcification can be described and correlated with clinical and physical findings. In the current era of medical reform, cost containment is an issue when choosing diagnostic tools. In studies of the medicare population, the projected cost savings of substituting musculoskeletal ultrasound for MRI would be more than $6.9 billion in the period between 2006–2020.¹¹ Large cost savings could help influence physicians and insurance providers regarding the benefit of using this diagnostic imaging option over MRI. The limitations of MSK ultrasound imaging are minor; and they include operator dependency and a learning curve. Those who use MSK ultrasound must be properly trained to achieve valid and reliable test results. Certification training in the use of musculoskeletal ultrasound as a diagnostic tool is currently lacking, but courses are being developed to provide health care providers with the opportunity to learn proper assessment techniques and earn valid certifications.

Figure 1.

Terason Ultrasound Unit (Teratech Corporation, Burlington, MA).

Figure 2.

The elbow is flexed to 25° and the upper arm is held in external rotation approximalely 65° of abduction. The wrist is in a supinated position.

Figure 3.

A counter force is applied to the radial side of elbow by a screw-threaded device with diode digital light measuring device.

Figure 4.

Telos Stress Device Procedure:

1. At 0 stress an initial sonogram is taken to provide a baseline

2. The screw shaft device applies a valgus stress.

3. Sequential sonograms are then taken 10 and 15 kilo-pascals of stress (as read on the diode digital light-measuring device).

Figure 5.

Ultrasound 12 MHZ frequency transducer is placed in a longitudinal plane on the medial side of the elbow. Note that the transducer is parallel with the forearm.

Figure 6.

Ultrasound image of medial elbow without imposed stress. Note the origin of the common flexor tendon (F), the epicondyle (E), the trochlea (T), and ulna (U) with the UCL identifiable between the two arrows.

Figure 7.

Example of a diagnostic ultrasound image of the medial elbow at 9 mpa of force. The arrowheads demonstrate small hypoechoic areas that correlate to a tear within the anterior band of the UCL. Arrow is pointing to the anterior band of UCL. Common flexor tendon (F), medial epicondyle (me) are identified.

Figure 8.

Example ultrasonographic measurement of the ulnohumeral joint to assess amount of opening within the joint under valgus loading.

Figure 9.

Radiograph demonstrating Telos Stress Device placement and valgus stress being applied to the elbow.