Common extensor tendon injury

Common extensor tendon injuries of the elbow include partial and complete tears or detachment of the common extensor tendon origin of the elbow and are commonly associated with lateral epicondylitis ^1-4.

Epidemiology

Common extensor tendon injuries are the most common acute tendon injuries of the elbow and are more frequent than injuries of the common flexor origin, distal biceps tendon injuries or triceps tendon injuries ¹.

Associations

Common extensor tendon injuries are associated with the following ^1-7:

• lateral epicondylitis (tennis elbow)

• corticosteroid injections

• lateral collateral complex ligament injuries, especially lateral ulnar collateral ligament ⁶

• posterolateral rotatory instability ⁷

Diagnosis

The diagnosis of common extensor tendon injuries can be made by the combination of clinical findings and imaging features on ultrasound or MRI ^1,3.

Clinical presentation

Patients often present with a history of lateral epicondylitis with typical symptoms such as lateral elbow pain, tenderness and swelling. They might have been treated with corticosteroid injections. On top of that, they might report an acute episode of sharp pain in the lateral elbow during work or training ¹. They might also complain of increased laxity.

Pathology

The pathological correlate is a fiber disruption of the common extensor tendon and occurs as an intrasubstance tear, partial-thickness or full-thickness tear and can affect one or more of the tendons forming the common extensor origin.

Etiology

Common extensor tendon injuries usually occur either as a result of an acute traumatic event such as an elbow dislocation or as the result of repetitive microtrauma such as lateral epicondylitis ^1-3. Previous corticosteroid injections have been described in association with those injuries ¹.

Classification

Common extensor tendon injuries of the elbow can be roughly classified as partial-thickness and full-thickness tears.

Partial-thickness tears have been further graded into the following by one study ³:

• high-grade tear (>50% thickness)

• low-grade tear (<50%) thickness)

• suspected tear (possible but not clearly evident)

Radiographic features

Ultrasound

Ultrasound might show ill-defined hypoechoic lesions within the extensor tendon with varying degrees of fiber disruption accompanied by interposed hematoma in the acute situation ^1,3.

It shows a high agreement to MRI concerning diagnosing high-grade tears even though the agreement of the lower grades especially the differentiation between low-grade tears and suspected tear is only moderate ³.

MRI

On MRI those injuries appear as focal defects of fluid signal intensity or fiber disruption within the common extensor tendon of varying degrees or even frank detachment ^2-4.

MRI can aid in the grading, the differentiation to lateral epicondylitis and the detection of associated injuries such as tears of the lateral collateral ligament complex ^2,3.

Radiology report

The radiological includes a description of the following:

• type (partial-thickness or full-thickness tear) and extent of the injury (tendons involved)

• associated injuries

  • lateral ulnar collateral ligament injury

  • radial collateral ligament injury

  • bony avulsions

Treatment and prognosis

Surgical treatment should be considered in larger common extensor tendon tears since they are less likely to respond to nonsurgical treatment and also if they are associated with injuries of the lateral collateral ligament complex of the elbow ⁸.

Differential diagnosis

Conditions that might mimic the clinical presentation or imaging appearance of common extensor tendon injuries of the elbow include lateral epicondylitis which is characterized by micro tears ⁹.