INTRODUCTION

Lateral epicondylitis (tennis elbow) is an overuse injury that arises from activities or tasks that involve repetitive gripping or wrist extension, forearm supination, or radial deviation.^[1] Lateral epicondylitis is one of the most common upper extremity disorders, affecting up to 3% of adults in the United States (US).^[2,3] According to national insurance claims data, the incidence of lateral epicondylitis remained steady between 2007 and 2014 in the US, as did the rate of surgical intervention to treat this disorder.^[4] Total annual healthcare costs associated with lateral epicondylitis, however, increased significantly during the same time period (P = .006), suggesting a growing burden on the US healthcare system.^[4]

Lateral epicondylitis is diagnosed more frequently in people older than 40 years and occurs in men and women equally.^[4] Any activity (eg, forced wrist extension involved in the backhand stroke in tennis) involving the repeated use of the extensor carpi radialis brevis (ECRB) muscle, or other supinator or wrist extensor muscles, can cause lateral epicondylitis.^[1,5] Originally described as an inflammatory condition, lateral epicondylitis is now more widely recognized as a degenerative process, in part because of the lack of inflammatory cells present on histologic examination.^[5] The complete pathophysiology of lateral epicondylitis remains poorly understood but is believed to originate with microtrauma caused by repetitive mechanical stress, leading to chronic degenerative tendinopathy.^[6] This brief publication includes a review of initial approaches for diagnosing and managing lateral epicondylitis, with a focus on the typical imaging methods used during diagnosis and the value of this imaging in the routine care of patients.

INITIAL DIAGNOSTIC AND MANAGEMENT APPROACHES

The diagnosis of lateral epicondylitis is typically based on clinical history and physical examination. Characteristic features include a history of lateral elbow pain that worsens with use, focal tenderness over the bony prominence of the lateral epicondyle, and pain with resisted wrist extension.^[1] At present, no consensus exists regarding optimal management.^[1] The primary goals of treatment are to control pain, preserve function, and facilitate healing.^[2] Initial management involves a “watch-and-wait” strategy that includes a combination of:

• Rest. Resting from the aggravating activity, modifying the activity, and avoiding overuse are the cornerstones of care.^[7] The combined use of RICE (rest, ice, compression, elevation) can provide pain relief, particularly during early management.^[7]
• Bracing. Wrist splints can prevent overuse during activities of daily living.^[7] Counterforce braces such as forearm straps and sleeve orthoses can reduce tension in the forearm extensor muscles, thereby relieving pain and improving grip strength.^[8]

• Nonsteroidal anti-inflammatory drugs (NSAIDs). Given that the pathophysiology of lateral epicondylitis is largely degenerative rather than inflammatory, NSAIDs are not expected to have a disease-modifying effect. Instead, oral and topical NSAIDs are used for their analgesic properties. Evidence supports the use of topical NSAIDs, in particular, for up to 4 weeks of pain relief.^[9]
• Physical therapy. Options range from stretching and strengthening exercises to extracorporeal shock wave therapy and therapeutic ultrasonography.^[7,10]

Local corticosteroid injections are also used to alleviate acute symptoms.^[7] However, some studies have challenged their utility, suggesting that these injections provide short-term relief but worsen long-term outcomes; these findings may have contributed to a decrease in their use.^[11-13] Indeed, the annual rate of corticosteroid injections used to treat lateral epicondylitis fell from 23.3% in 2010 to 18.8% in 2017.^[13]

Most cases of lateral epicondylitis are self-limiting; in fact, 80% of cases resolve within 6 months, and 90% of patients recover within 1 year.^[14] Patients with persistent or severe symptoms that do not resolve with nonoperative treatment can be considered for surgery.^[5] Several surgical approaches are used to treat this condition, most of which involve debriding the abnormal fibrotic tissue of the ECRB.^[1] Each year, approximately 2% of patients with lateral epicondylitis undergo surgery.^[4]

ROLE OF IMAGING IN DIAGNOSIS AND TREATMENT PLANNING

Ultrasonography, radiography, and magnetic resonance imaging (MRI) have been explored as potential tools to enhance the diagnostic evaluation of lateral epicondylitis and thereby guide treatment decisions.^[15-17] However, their role in patient management has been unclear.

Ultrasonography

Ultrasonography is a widely available, inexpensive, and reliable option for visualizing soft-tissue involvement when a diagnosis of lateral epicondylitis is unclear.^[2,17] In particular, the absence of grayscale ultrasonography changes and neovascularity, as assessed by color Doppler, is helpful in ruling out lateral epicondylitis.^[18] Given the wide degree of anatomic variability in the ECRB tendon in affected patients, ultrasonography is also used to support the accuracy of needle positioning in patients receiving corticosteroid injections.^[19]

Beyond these uses, however, ultrasonography appears to play a limited role in patient management.^[20] For instance, in a study of 60 patients with chronic lateral epicondylitis, the 3 ultrasonography measurements assessed—tendon thickness, color Doppler activity, and presence or absence of bone spur—had no correlation with pain, disability, Patient-Rated Tennis Elbow Evaluation score, or disease duration, which are important considerations for individualized treatment planning.^[20]

Radiography

Radiography is less costly than other imaging modalities at most institutions and reveals the distinctive abnormalities associated with lateral epicondylitis, such as calcification at the lateral epicondyle. In one study of 245 patients with lateral epicondylitis, 115 (47%) were found to have lateral epicondyle calcifications using standard digital radiography.^[15] Imaging also revealed 113 additional radiographic findings in 85 patients (35%), most commonly olecranon enthesophytes (21%), medial epicondylar enthesophytes (13%), and coronoid osteophytes (9%).

Of note, patients had similar clinical features regardless of the presence or absence of calcifications or size of the calcified lesions (Table 1).^[15] These clinical features included pain levels, assessed by the visual analog scale (VAS); symptom duration; functional impairment, determined by the Disabilities of the Arm, Shoulder, and Hand (QuickDASH) outcome measure; and history of steroid injection. Moreover, radiographic findings did not influence the treatment plan for any patient, suggesting that this imaging modality does not have a role in patient evaluation or treatment decision making. All patients were managed with a mix of activity modification, bracing, NSAIDs, physical therapy, and steroid injections, and no patients underwent surgery.^[15]

Table 1. Characteristics of Patients With and Without Radiographic Calcifications^a

^aData derived from Shillito M, Soong M, Martin N. Radiographic and clinical analysis of lateral epicondylitis. J Hand Surg Am. 2017;42(6):436-442.
^bVAS scores range from 0 (no pain) to 10 (severe pain).
^c QuickDASH scores range from 0 (no disability) to 100 (severe disability).

MRI

MRI helps differentiate the morphologic changes of lateral epicondylitis, with similar diagnostic specificity to but greater sensitivity than ultrasonography.^[21] In clinical trials, MRI has been used to evaluate responses to treatments for lateral epicondylitis. For example, in a trial of 30 patients randomly assigned to undergo corticosteroid injection or immobilization, MRI detected persistent degenerative changes at the 6-week follow-up visit in 66% of patients who had achieved clinical remission.^[22] MRI findings may also correlate with clinical symptoms: in a recent study of 51 patients with lateral epicondylitis, MRI findings were significantly associated with the pain VAS scores reported by patients (P = .03).^[23]

For the routine care of lateral epicondylitis, the role of MRI in patient evaluation and treatment decision making has been less clear. Broadly, an imaging study should provide data to make a diagnosis or direct treatment. However, lateral epicondylitis is a clinical diagnosis and, to date, MRI has not been useful in directing treatment modalities.^[24] In fact, using MRI increases healthcare costs and does not affect diagnosis or surgical/nonsurgical management.^[24] Substantial cost savings would occur if MRI were not used in the routine management of this condition.

Findings from a recent observational study of 44,471 patients enrolled in a national insurance claims database show the complex relationship between MRI use and treatment choices.^[16] The study included records from patients who were diagnosed with lateral epicondylitis between 2008 and 2016 and examined national and regional patterns in MRI use and rates of surgical treatment, corticosteroid injections, and physical/occupational therapy.^[16]

In total, only 998 (2.2%) of the 44,471 patients included in the study underwent MRI. Longitudinal trends, however, showed a steady increase in MRI use.^[16] Nationwide, the annual rate of MRI use for lateral epicondylitis increased by 65% between 2008 and 2016. MRI use was more common in the South, where patients were 36% more likely to undergo MRI than patients in the Midwest (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.16-1.59; P < .001). Although regional variations exist, they cannot be necessarily explained by a single factor. Moreover, despite the lengthy and self-limiting natural history of lateral epicondylitis, many clinicians chose to use MRI early in the disease course. In fact, nearly one-third of MRI scans occurred within 90 days of the initial diagnosis.^[16]

This study also found that MRI use was associated with the increased use of surgical and nonsurgical interventions (Table 2).^[16] Among patients who underwent MRI, 20.3% received surgical treatment, compared with 2.1% of patients who did not undergo MRI. This represents an 11-fold increase in the likelihood of surgical treatment after MRI (OR, 11.0; 95% CI, 9.3-13.0; P < .0001). In addition, patients who underwent MRI were nearly twice as likely to receive a steroid injection (OR, 1.90; 95% CI, 1.65-2.20; P < .0001) and twice as likely to receive physical/occupational therapy (OR, 2.03; 95% CI, 1.70-2.41; P < .0001).^[16]

MRI use was also associated with increased healthcare costs in this study. The average total reimbursement for lateral epicondylitis treatment was $1,824 for patients who underwent MRI and $103 for patients who did not undergo MRI (P < .0001).^[16]

Table 2. Treatment and Reimbursement for Lateral Epicondylitis by MRI Status^a

NA = not available; PT/OT = physical or occupational therapy.
^aData derived from Fogel N, Zhuang T, Shapiro LM, et al. Utilization of MRI in diagnosis and treatment of tennis elbow in the United States. Presented at: American Academy of Orthopaedic Surgeons (AAOS) Annual Meeting; August 31-September 4, 2021; San Diego, CA. Abstract 144.

CONCLUSION

To date, evidence does not support the use of imaging to guide treatment decisions in the routine care of lateral epicondylitis. Ultrasonography appears useful only in supporting a differential diagnosis when clinical diagnosis is challenging and in improving the accuracy of needle positioning for corticosteroid injections. Radiographic images do not provide any additional insight, beyond what can be determined clinically, to inform diagnosis or treatment decisions. The increasing use of MRI, particularly in the acute setting, appears to contribute to the possible overuse of surgical treatment while increasing healthcare expenses. Decreasing the use of unnecessary imaging can help decrease costs without adversely affecting evidence-based care for patients with lateral epicondylitis.