Lateral Epicondylitis (Tennis Elbow)

Etiology

Tennis elbow is often an overuse injury primarily due to repetitive strain from tasks and activities that involve loaded and repeated gripping and/or wrist extension. It historically occurs in tennis players but can result from any sports that require repetitive wrist extension, radial deviation, and/or forearm supination. It is also seen in athletes who play squash and badminton, and other sports or activities that require similar movements. This condition is often precipitated by poor mechanics and technique or improper equipment in the athletic patient population.[3]

Epidemiology

Tennis elbow is the most common cause of elbow symptoms in patients presenting with elbow pain in general.  The condition tends to affect men and women equally. The annual incidence is one to three percent in the United States. Despite the condition being commonly referred to as tennis elbow, tennis players make up only 10% of the patient population. Half of all tennis players develop pain around the elbow, of which 75% represent true tennis elbow. It is more common in individuals older than 40 years of age. Smoking, obesity, repetitive movement for at least two hours daily, and vigorous activity (managing physical loads over 20 kg) are risk factors in the general population for developing this condition. The natural course of the condition is favorable, with spontaneous recovery within one to two years in 80% to 90% percent of the patients.[4][5][6]

Pathophysiology

This condition is primarily a degenerative overuse process of the extensor carpi radialis brevis and the common extensor tendon. Aside from degenerative changes, the histological findings include granulation tissue, micro-rupture, an abundance of fibroblasts, vascular hyperplasia, unstructured collagen, and a notable lack of traditional inflammatory cells (macrophages, lymphocytes, neutrophils) within the tissue. The term has been previously described as angiofibroblastic dysplasia based on multiple histologic studies describing its microscopic appearance and characteristics.[7][8] Ultrasound evaluation often reveals calcifications, intra-substance tears, marked irregularity of the lateral epicondyle, and thickening and heterogeneity of the common extensor tendon.[9]

Histopathology

Multiple studies reporting the histologic appearance of pathologic ECRB specimens characterize any combination of the following characteristics:[8]

• Hypertrophic or abundant fibroblasts
• Collagen disorganization
• Vascular hyperplasia
• Lack of inflammatory cells

History and Physical

Patients will typically report pain with an insidious onset, but upon further questioning, they will often relate an overuse history without a specific inciting traumatic event. The pain commonly occurs one to three days after an unaccustomed activity that involves repeated wrist extension.

The history may reveal new equipment use or an atypical workout circumstance such as an abnormally intense or prolonged workout in an athlete. This condition can also be precipitated by an acute injury or strain, such as lifting a heavy object or performing a hard backhand swing in tennis. This acute injury can lead to a more chronic process (i.e., acute-on-chronic overuse injury). The pain is usually over the lateral elbow that worsens with activity and improves with rest. The pain can vary from being mild, for example, with aggravating activities like tennis or the repeated use of a hand tool, or it can be such severe pain that simple activities like picking up and holding a coffee cup or a coffee cup sign will act as a trigger for the pain.

On examination, the point of maximal tenderness is usually over the lateral epicondyle, occasionally in a focal, distal location about 1 cm to 2 cm from the lateral epicondyle itself. The palpation of the entire tendon may have some degree and discomfort, and the connecting muscle may exhibit significant tightness. The patient’s pain will increase or be reproduced with resisted wrist extension, especially when the elbow is extended and the forearm is pronated. Resisted extension of the middle finger while the elbow is extended is particularly painful secondary to increased stress placed on the tendon, further supporting the diagnosis. Notably, there should be an absence of radicular symptoms or numbness/tingling. These symptoms suggest an alternative process such as radial nerve entrapment, although these conditions can coexist.[10]

Evaluation

Lateral epicondylitis is a clinical diagnosis, and imaging is often not necessary. A provider may consider obtaining an elbow radiographic series (anteroposterior and lateral) if other injuries or conditions are suspected by history and/or physical exam. Other conditions warranting potential imaging workup include evaluating concomitant degenerative joint changes, fractures, tumors, or bursitis. If the patient is not responding to nonoperative management modalities, the provider may consider ordering an MRI or ultrasound to evaluate for tears, stress fractures, or osteochondral defects.[11]

Treatment / Management

Nonoperative Management

First-line management for the treatment of lateral epicondylitis includes rest from offending activity as guided by the level of pain. Ice after activity and oral/topical NSAIDs can be used to help with pain control. Forearm counterforce straps are prescribed to relieve tension at the lateral epicondyle. These should be worn during activity. The role of counterforce straps is relatively controversial as some patients may report pain over the area of maximal tenderness secondary to direct mechanical compression on the area itself. Brace use in the form of a cock-up wrist splint can be prescribed to take the stress off of the wrist extensors.[10]

Occupational or physical therapy focusing on forearm stretching and strengthening and progression to eccentric muscle strengthening of the common extensor tendon has also shown to be helpful. If the pain does not respond to conservative measures, consider more advanced or invasive techniques such as topical nitrates, botulinum toxin, autologous platelet-rich plasma, and dextrose prolotherapy.

Surgical Management

Surgery should be considered as a last resort in the management of lateral epicondylitis. Prolonged nonoperative management (i.e., 6- to 12-months) should be attempted before considering surgical management.  Specific surgical techniques utilized vary throughout the literature. Most surgeons prefer varying degrees of ECRB debridement and/or release of the tendinous origin at the lateral epicondyle. In the setting of the surgeon electing to forego an actual ECRB detachment, a generous debridement should be performed at the ECRB origin with confirmation of debridement of the pathologic tissue and stimulation of a healthy, bleeding, bony bed of tissue at the lateral epicondyle to help stimulate healing potential.[12][13](A1)

Differential Diagnosis

The differential diagnosis for lateral epicondylitis includes but is not limited to any of the following conditions:[14]

• Elbow bursitis
• Cervical radiculopathy
• Posterolateral elbow plica
• Posterolateral rotatory instability (PLRI)
• Radial nerve entrapment
• Radial tunnel syndrome
  • palpation 3 to 4 cm distal and anterior to the lateral epicondyle
  • pain with resisted third-finger extension
  • pain with resisted forearm supination
• Occult fracture(s)
• Capitellar osteochondritis dissecans
• Triceps tendinitis
• Radiocapitellar osteoarthritis
• Shingles

Prognosis

The prognosis for lateral epicondylitis is generally good. Most patients will have pain relief within 12 months of conservative treatment (ice, rest, and anti-inflammatory medications). For patients who do not improve with initial treatment, various physical and occupational therapies can be helpful. Patients who fail to follow through on their therapy plan frequently have a recurrence of symptoms.

Complications

Complications of lateral epicondylitis can include recurrence of the injury when normal activity is resumed, rupture of the tendons with repeated steroid injections, and failure to improve conservative treatment.

Postoperative complications can include the following:

• Failing to address concomitant pathology 
  • Patients report inferior outcomes and lack of improvement if the primary cause of symptoms is not addressed; patients should be educated regarding the risks and benefits of surgery; the former include but are not limited to infection, blood loss, neurovascular injury, continued pain, stiffness, or continued or worsening overall dysfunction. 
  • Radial nerve entrapment can be missed or not addressed clinically in up to 5% of patients being managed for lateral epicondylitis.
• Iatrogenic LUCL injury
  • Occurs iatrogenically with increased risk if the surgical dissection extends beyond the radial head equator 
  • Postoperative iatrogenic posterolateral rotatory instability (PLRI) can develop if the extension or LUCL compromise is significant.
• Iatrogenic neurovascular injury
  • Radial nerve injury
• Heterotopic ossification
  • Decrease risk via copious saline irrigation following decortication and debridement
• Infection