Ultrasonography in diagnosis of distal biceps tendinosis: A case series

Abstract

Introduction:

Biceps tendinosis, a milder form on the spectrum of biceps tendinopathy, is unusual at the distal insertion site. Patients with distal biceps tendinosis may experience pain and dysfunction which could inhibit their activities of daily living. Diagnosis of distal biceps tendinosis may be facilitated with ultrasonography (US), whose accuracy is increasingly recognised, while providing many benefits over other modalities, like magnetic resonance imaging (MRI).

Case report:

We report two cases of distal biceps tendinosis diagnosed by US with clinical details, imaging findings and patient management. Two patients present with elbow pain after nontraumatic activities. US revealed a thickened distal biceps tendon with mild heterogeneous hypoechogenicity without fibre disruption or retraction in both cases and evidence of hyperemia on Doppler with surrounding bursal fluid in case 2.

Discussion:

Tendinosis has variable aetiologies, but US commonly cannot differentiate among these; therefore, patient’s clinical history is the major component in determining the underlying cause. Chronic progression of tendon pathology leads to partial and full thickness tears. Tendinosis has a characteristic US appearance. US has many benefits and clinicians may use this modality to assess possible pathological structures with ease, convenience and efficiency compared with using MRI.

Conclusion:

Distal biceps tendinosis may present with clinical symptoms of pain and decreased activities of daily living, and may progress to more severe forms of tendinopathy. Early diagnosis is beneficial for the treatment outcomes of this condition. US can visualise distal biceps tendinosis with reliability, providing an alternative diagnostic technique with many benefits compared with MRI.

Introduction

The long head of the biceps brachii originates at the scapular supraglenoid tubercle from the superior glenoid labrum posterior fibres and travels as the lateral muscle belly to become the deep component of the distal biceps tendon, which inserts at the proximal portion of the radial tuberosity.^1–5 The short head of the biceps brachii originates at the coracoid process and travels as the medial muscle belly to become the superficial component of the distal biceps tendon, which inserts at the apex and distal aspect of the radial tuberosity.^1,2,5 The entire distal biceps tendon is completely surrounded by a paratenon, composed of loose connective tissue.^4,6 The lacertus fibrosus (bicipital aponeurosis) is a continuation of the anterior middle fibres of the distal biceps myotendinous junction and travels in a medial direction distally to converge with the deep fascia overlying the common flexor muscle group.^2,4–7 One study describes the normative measurements for distal biceps tendon to be around 8.38 mm (1.87 SD) in width and 2.73 mm (0.69 SD) in thickness. ⁶

The biceps brachii, a muscular structure in the anterior compartment of the arm, functions as an arm and forearm flexor along with a forearm supinator.^1,2,6,7 Biceps injuries commonly occur at its proximal aspect near the glenoid region causing pain and restriction of motion, but distal biceps injuries can be just as debilitating.^1,3,8 A few conditions exist involving the distal biceps tendon such as tendinitis, tenosynovitis, tendinosis, partial tear, complete tear, bicipitoradial bursitis and enthesopathy.^1,4,8 The most common distal biceps injury is a complete rupture of the tendon and easily detected via ultrasonography (US).^1,4–7,9,10 Less commonly at the distal biceps, milder tendinopathic conditions may occur, such as distal biceps tendinosis, which may be visualised using US.^5,8,10 Tendinosis is a chronic condition resulting from a loss of the normal collagen structure with tendon thickening and is histologically described as collagen disorientation with myxoid, hyaline, fatty, fibrinoid, or calcific degeneration and associated tendon thickening.^10,11 There is variable symptomology associated with tendinosis therefore the true prevalence in the population is unknown and has not been studied in great detail. ⁸ The gold standard for imaging distal biceps tendon injuries currently is magnetic resonance imaging (MRI). ⁴

US provides high sensitivity for full thickness distal biceps tendon tears and good sensitivity for differentiating between full and partial thickness distal biceps tendon tears.^4,9 Other benefits of using US, in contrast to MRI, include widely available access, cost-effectiveness, time-efficiency, ease of contralateral comparison and dynamic assessment.^3,4,7,9,11 Furthermore, US appearance of tendinosis, as heterogeneous hypoechogenic tendon thickening with loss of normal fibrillar echotexture and no fibre disruptions, is consistent regardless of the tendon imaged.^5,10,11 Another US finding that may be present with tendinosis is signal on power Doppler, representing neovascularity. ¹¹ There is limited research presenting US evaluation for distal biceps tendinosis.^4,9 This article presents two cases in which US findings assisted in the diagnosis of distal biceps tendinosis.

Case reports

Case 1

A 44-year-old Caucasian male patient presented to a chiropractic clinic with right anterior elbow and shoulder pain. The elbow pain was localised near the distal biceps insertion, described as constant and sharp, rating 7/10 on the visual analogue scale and provocative with supination. The patient stated the pain originated from playing racquetball but denied trauma. The patient had a purported 2-year history of arthritis which was treated with Methotrexate and adalimumab (Humira). When the patient was seen in the office, he was gradually decreasing the Methotrexate and taking two doses a month of adalimumab (Humira).

Per inspection, no ecchymosis nor oedema were noted around the areas of elbow and shoulder pain. Palpation revealed tenderness over the anterior aspect of the right elbow at the distal biceps tendon. In addition, localised tenderness was noted over the anterior aspect of the right shoulder. All active ranges of motion for the right elbow were full, similar when compared with the contralateral side, although supination provoked pain. Resisted range of motion was provocative against supination of the right wrist. In addition, examination of the right shoulder revealed full active ranges of motion, but pain provocation with shoulder abduction approximately between 90° and 110° and with Speed’s test.

The patient was treated with Graston technique performed along the biceps muscle and anterior deltoid for 8 to 12 minutes. Manual therapy was performed in the cervical, thoracic, right elbow and right wrist regions. In addition, therapeutic ultrasound was performed at the distal biceps tendon and anterior shoulder for 4 minutes each using a frequency of 1.5 MHz. The patient was instructed to perform at-home exercises every other day consisting of three sets of 8–12 reps of eccentric biceps curls with light resistance within pain tolerance. Three sets of 8–12 reps of pronation and supination twists using a dumbbell as light resistance were also prescribed. After a trial of care consisting of two visits per week for 3 weeks, the patient experienced limited benefit. He rated the anterior right elbow pain as 5/10 on the visual analogue scale. He reported provocation with increased movement and applied pressure but palliation with chiropractic treatment and rest.

The patient was referred for US to further assess his right elbow and shoulder to rule-in subacromial bursitis and biceps strain. The US examination was performed using a GE LOGIQ E9 XDclear unit with a GE ML6-15 Matrix Linear probe using a frequency of 10 MHz. Power Doppler was used to evaluate hyperemia using a frequency of 6.3 MHz and pulse repetitive frequency of 0.6 MHz. The distal biceps tendon was imaged using a medial approach. US displayed a thickened distal biceps tendon with hypoechogenicity at the insertion to the radial tuberosity and no evidence of hyperemia (increased blood flow), indicating distal biceps tendinosis (Figure 1(a) and (b)). Also visualised on US were focally thickened subacromial/subdeltoid bursa and narrowed acromioclavicular joint with associated osteophytosis, consistent with subacromial/subdeltoid bursitis and acromioclavicular joint arthrosis, respectively.

Figure 1.

Ultrasonography of the right distal biceps tendon via medial approach (a) through the pronator muscle (PM). Distal biceps tendon (arrow) is enlarged with hypoechoic signal, without evidence of fibre disruption, attaching to the radial tuberosity (RT). Power Doppler image (b) showing no evidence of hyperemia in the distal biceps tendon. Colour flow present is located within the brachial artery.

Following the US examination, the patient was referred to an orthopaedist who performed platelet-rich plasma (PRP) injections around the anterior right elbow and shoulder. The patient was instructed to cease racquetball for 6 weeks. After 6 weeks, the patient-reported resolution of shoulder pain and moderately improved elbow pain. At his last follow-up, he stated that his elbow was significantly improved and experienced only mild exacerbation with extended play.

Case 2

A 39-year-old Caucasian male presented to a chiropractic clinic with localised left anterolateral elbow pain described as general aching with sharp pain of 2 weeks in duration. The patient stated the pain began immediately after hyperextending his left elbow while pushing his grandson in a cart. The patient described the pain as a 4/10 on the visual analogue scale and noted provocation with elbow flexion with resistance, complete elbow extension and hand supination. The patient self-administered treatment included ice packs and massage to the distal lateral aspect of the biceps, which was palliative. The patient denied previous injury or chronic complaints related to his left elbow. No chronic illnesses or hospitalisations were reported.

Per inspection, no ecchymosis nor oedema were noted around the elbow. Palpation revealed tenderness and increased temperature, in comparison with the contralateral side. Tenderness was localised over the anterolateral aspect of the left elbow at the insertion of the biceps tendon on the radial tuberosity. In addition, localised tenderness was noted over the lateral humeral epicondyle and common extensor musculature. Clinical assessment revealed pain with resisted flexion of forearm at 90° and a positive distal biceps provocation test (increased pain with elbow flexion against resistance in forearm pronated position compared with forearm supinated position). The patient also complained of pain with resisted wrist extension at the left humerus lateral epicondyle region.

The patient’s treatment plan consisted of two visits per week which included class 4 laser therapy, K-tape, light soft tissue therapy and manual therapy to the elbow. Recommendations for at home stretches and exercises, continued cryotherapy and avoidance of heavy lifting with the left arm were provided. Following a trial of care consisting of four visits, the patient was referred for US to rule out distal biceps tendon tear and bicipitoradial bursitis. The US examination was performed using a GE LOGIQ E9 XDclear unit with a GE ML6-15 Matrix Linear probe using a frequency of 10 MHz. Power Doppler was used to evaluate hyperemia using a frequency of 6.3 MHz and pulse repetitive frequency of 0.5 MHz. The distal biceps tendon was imaged using a medial approach. US visualised a thickened distal biceps tendon with mild heterogeneous hypoechogenicity, evidence of hyperemia on Doppler and surrounding bursal fluid (Figure 2(a) and (b)). These findings indicated a diagnosis of distal biceps tendinosis with bicipitoradial bursitis. Also visualised on US were hypoechogenic regions with hydroxyapatite deposition at the undersurface of the common extensor tendon and associated hyperemia on Doppler, which indicated common extensor tendinopathy.

Figure 2.

Ultrasonography of the left distal biceps tendon via medial approach (a) through the pronator muscle (PM). Distal biceps tendon (arrow) is enlarged with heterogeneous hypoechoic signal, without evidence of fibre disruption, attaching to the radial tuberosity (RT). Presence of homogeneous hypoechoic signal subadjacent to the distal biceps tendon indicating fluid within the bicipitoradial bursa (double asterisk). Power Doppler image (b) showing evidence of hyperemia (arrowhead).

The patient continued with care and showed a positive response to treatment even though he was non-compliant with his treatment plan and home care exercises. The patient stated his pain and discomfort reduced from 4/10 to 0.5/10 on the visual analogue scale and noticed improvement in his abilities to perform normal daily activities. The patient self-discharged from care before reaching maximum medical improvement.

Discussion

We present two uncommon cases of distal biceps tendinosis with US findings. The visualisation of the distal biceps tendon can be challenging based on arm anatomy, oblique course to its insertion and deepness of the structure. ⁵ In addition, tendinopathy of the biceps is uncommon distally and occasionally presents as tendinosis. Diagnosis of distal biceps tendinosis may be acquired with US, whose accuracy is increasingly recognised, while providing many benefits over other modalities, like MRI.

Tendinopathy is a large spectrum of diagnoses that ranges from tendinosis to complete tears.^1,4,8 On the milder side of the spectrum, tendinosis can be caused by mechanical (overuse), degenerative (age/vascularity), or inflammatory factors. ¹¹ A combination of these variables are often present. US commonly cannot differentiate among the aetiologies; therefore, the patient’s clinical history is the major component in determining the underlying cause. ¹¹ As normal tendons degenerate, fibres become disoriented and the healing response leads to mucoid degeneration and neo-vascularisation, indicating tendinosis. ¹¹ This can be visualised histologically as collagen disorientation with myxoid, hyaline, fatty, fibrinoid, or calcific degeneration and associated tendon thickening. ¹¹ Chronic progression of tendon pathology leads to partial and full thickness tears.^11,12 Although the true prevalence in the population is unknown and has not been studied in great detail, it is likely the occurrence of tendinosis may be more common than the literature suggests. ⁸ This highlights the importance of early diagnosis of tendinosis before progression to severe tendinopathy. This is particularly relevant when patients present with pain, decreased range of motion, or difficulties with activities of daily living.

US is a useful modality for the assessment of the distal biceps tendon. ⁵ There are different approaches for visualising the distal biceps tendon named based on where the ultrasound probe is placed on the elbow. ⁵ The anterior approach places the probe along the long-axis of a fully extended arm with a heavier pressure along the distal aspect of the probe (heel toe manoeuvre) to visualise the distal biceps tendon located lateral to the brachial artery. ⁵ The medial approach places the probe in parallel long-axis of a supinated and 90° flexed elbow through the pronator muscle (pronator window) to visualise the distal biceps tendon to the insertion located deep to the brachial artery. ⁵ The lateral approach places the probe along the parallel long-axis of a pronated and 90° flexed elbow through the extensor muscles and supinator muscle to visualise the distal biceps tendon. ⁵ The dorsal approach places the probe short-axis to the radius with the elbow in flexion and pronation (cobra position) through the supinator muscle to visualise the distal biceps tendon to the insertion obliquely. ⁵ The protocols used by the authors are mainly the medial and dorsal approach since there is better visualisation of the distal biceps tendon directly inserting to the radial tuberosity.

There are definitive US characteristics defining the normal appearance of tendons in both longitudinal (long-axis) and transverse (short-axis) planes. ¹¹ Longitudinal imaging of tendons show a regular, uniform structure with internal fascicular pattern as multiple, parallel echogenic lines (Figure 3). ¹¹ Transverse imaging of tendons show a regular, uniform circular or ovoid structure with internal pattern of multiple echogenic dots or lines. ¹¹ One study describes the normative measurements for distal biceps tendon to be around 8.38 mm (1.87 SD) in width and 2.73 mm (0.69 SD) in thickness. ⁶

Figure 3.

Normal distal biceps tendon for comparison in another patient. Medial approach to biceps tendon through the pronator muscle (PM) and brachial artery (BA). Parallel tendon borders with normal fibrillar echotexture and uniform echogenicity attaching to the radial tuberosity (RT).

In contrast, tendinosis appears on US as heterogeneous hypoechogenic tendon thickening with no fibre disruptions, these finding are stereotypical in tendons.^5,10 An additional finding for an abnormal tendon includes power Doppler signal indicating hyperemia and/or neo-vascularisation. ¹¹ In case 1, US was performed using a medial approach through the pronator window to visualise the right distal biceps tendon inserting to the radial tuberosity. The distal biceps demonstrated tendon thickening and heterogeneous hypoechogenic fibrillar pattern. Power Doppler was performed for evaluation of hyperemia/neo-vascularisation, and no evidence of signal was visualised within the pathological distal biceps tendon. In case 2, US was performed using a medial approach through the pronator window to visualise the left distal biceps tendon inserting to the radial tuberosity. The distal biceps demonstrated mild heterogeneous hypoechoic signal with tendon thickening. There was homogeneous hypoechoic signal surrounding the distal biceps tendon indicating bicipitoradial bursitis. Power Doppler was performed for evaluation of hyperemia/neo-vascularisation and signal was visualised within the pathological distal biceps tendon. In both patient cases, there was no evidence of biceps tendon fibre disruption or retraction. The lack of internal fibre disruption helps differentiate between tendinosis and partial tear on the spectrum of biceps tendinopathy. ⁵

US is increasingly utilised in the outpatient clinical setting as a result of its availability, time-efficiency, cost-effectiveness, ease of comparing bilateral structures, capacity for dynamic imaging and sensitivity for visualising pathological tissue.^1,4,7 Clinicians may assess possible pathological structures with ease, convenience and efficiency compared with MRI. The current gold standard for visualising the distal biceps tendinosis is MRI. ⁴ Abnormal findings include high signal intensity within the tendon on gradient echo or T1 sequences along with enlargement and contrast enhancement.^4,11,12 These MRI findings are similar to US imaging characteristics for distal biceps tendinosis, therefore a similar classification system can be utilised. ⁴ The MRI classification system describes major injuries (complete tears, high-grade partial tears) needing surgical intervention and minor injuries (low-grade partial tears, tendinosis) treated using conservative measures. ⁴ With surgical intervention as confirmation, US has shown high sensitivity (98%) for major injuries while inconclusive for minor injuries. ⁴ Further research is needed to confirm the true sensitivity and specificity of US for minor distal biceps injuries, such as tendinosis. Hopefully, additional research will be promising.

Conclusion

Distal biceps tendinosis lies on the mild end of the tendinopathy spectrum, presenting with clinical symptoms of pain and decreased activities of daily living, and may progress to more severe forms of tendinopathy. Early diagnosis is beneficial for the treatment outcomes of this condition. This case series describes US features of tendinosis at the distal biceps, an uncommon location for presentation. US characteristics of tendinosis are increased tendon thickness, heterogeneous hypoechoic changes to internal tendon pattern, no visible internal fibre disruption and possible signal on power Doppler imaging. US is a useful modality as an alternative for MRI for imaging of tendon structures, but will need more research to fully validate the effectiveness of the modality for imaging milder tendinopathies, such as tendinosis.