Distal Triceps Tendon Injuries

Distal triceps ruptures are uncommon, usually caused by a fall on an outstretched hand or a direct blow. Factors linked to injury include eccentric loading of a contracting triceps, anabolic steroid use, weightlifting, and traumatic laceration. Risk factors include local steroid injection, hyperparathyroidism, and olecranon bursitis. Initial diagnosis can be complicated by pain and swelling, and a palpable defect is not always present. Plain radiographs can be helpful. MRI confirms the diagnosis and directs treatment. Incomplete tears can be treated nonsurgically; complete tears are best managed surgically. Good to excellent restoration of function has been shown with surgical repair.

Key points

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Distal triceps ruptures are uncommon injuries, usually caused by a fall on an outstretched hand or a direct blow.
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Eccentric loading of a contracting triceps has been associated with injury as well, particularly in professional athletes.
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Other common factors linked to injury are anabolic steroid use, weightlifting, and traumatic laceration.
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Some local and systemic risk factors include local steroid injection, hyperparathyroidism, and olecranon bursitis.
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The initial diagnosis can be complicated by pain and swelling, and a palpable defect is not always present.

Introduction

In contrast with distal biceps tendon injuries, distal triceps tendon injuries are relatively rare. Anzel and colleagues reviewed more than 1000 cases of tendon injuries and found triceps tendon injuries to be the least common, accounting for less than 1% of the cases. The triceps muscle is the primary and most important elbow extensor and is critical for normal upper extremity function.

Triceps tendon injuries are most commonly the result of a discrete injury and typically appreciated by the patient. There are several known risk factors for this injury. The tendon tear can be partial or complete. Complete tears are optimally treated with surgical repair, with the best results obtained with acute repair. Significant injuries may present with relative preservation of strength, sometimes resulting in a delay in diagnosis.

Anatomy

The triceps muscle is a pennate muscle with 3 heads: long, lateral, and medial. It is the only muscle located in the posterior compartment of the arm and is innervated by the radial nerve. The long head takes origin from the infraglenoid tubercle of the scapula as well as the inferior glenohumeral joint capsule. The lateral head originates from the posterior humerus lateral to the teres minor insertion, extending distally from the superior aspect of the spiral groove and the lateral intermuscular septum. The medial head originates from the posterior humerus distal to the spiral groove and medial intermuscular septum.

The insertion of the triceps tendon consists of a central tendon insertion onto the olecranon process as well as a lateral triceps extension ( Fig. 1 ). The lateral tendon expansion is continuous with the anconeus fascia and has a mean width of 16.8 mm. The total width of the triceps tendon is approximately 4 cm. The mean thickness of the central tendon insertion is 6.8 mm. The medial triceps tendon has a distinct, rolled medial edge and an insertion consistently confluent with the central tendon. The mean insertional width and length of the tendon proper are 20.9 mm and 13.4 mm, respectively. The mean distance from the olecranon tip to the tendon is 14.8 mm. The tendon width, thickness, and insertional dimensions correlate with the olecranon width. One study demonstrated a mean area of the footprint insertion of 466 mm ² , whereas a second study used a 3-dimensional modeling process to calculate the insertion area as 646 mm ² . ^, A more recent study from Barco and colleagues found 3 distinct insertional areas of the triceps tendon on the olecranon. These were the posterior capsular insertion, the deep muscular portion, and the superficial tendinous portion of the triceps with areas of 1.5, 1.2, and 2.8 cm, respectively ( Fig. 2 ). The deep muscular head corresponded to the medial head of the triceps and the tendinous portion corresponded to the long and lateral heads and correlated with the height of the specimen. The triceps inserted at a mean of 1.1 cm from the tip of the olecranon.

Risks factors

Triceps tendon injuries are most common in athletes. They have been found to be especially common in football players. They are most common in men and have found to be associated with anabolic steroid use. Local corticosteroid injection has also been linked an increased risk of triceps tendon rupture. ^, Other factors that may play a role in triceps tendon injury include hyperparathyroidism, renal osteodystrophy, hypocalcemic tetany, Marfan syndrome, osteogenesis imperfecta, rheumatoid arthritis, type 1 diabetes mellitus, and olecranon bursitis. ^, In a systematic review of 262 patients, the most common medical comorbidity was renal disease, being present in 10% of the patients with triceps tendon ruptures. Other common comorbidities included anabolic steroid use (7%) and local steroid injection (5%).

Mechanism of injury

Triceps tendon injuries usually occur as the result of a forceful eccentric contraction. Examples include weightlifting as well as the use of the arms by football lineman to push opponents. Direct blunt trauma to the posterior aspect of the arm is a less common mechanism. Rarely, a laceration to the posterior arm can cause a rupture of the tendon. A recent study showed triceps tendon tears occurring with the following frequency owing to different mechanisms: direct elbow trauma (44.9%), extension/lifting exercises (20.3%), overuse (17.4%), and hyperflexion or hyperextension (17.4%). An additional study showed similar results with the most common mechanisms of injury being fall (56.5%) and weightlifting (19%). The injury usually involves avulsion of the tendon from the bone but can occur at the muscle tendon junction.

Clinical evaluation

An accurate history is critical in diagnosing a triceps tendon rupture. The patient most commonly reports a discrete injury to the elbow, oftentimes with an associated sensation of tearing or a pop. They often complain of a loss of elbow extension strength. On physical examination, ecchymosis and swelling are often present over the posterior aspect of the arm in the case of an acute injury. A palpable divot may be present adjacent to the olecranon in the case of a retracted tear. Range of motion is typically full, although potentially limited by pain. Strength testing typically yields some degree of weakness with resisted elbow extension. In the case of a complete central tendon rupture with a preserved lateral triceps expansion, strength may be deceptively good. As a result, an accurate diagnosis by clinical examination only may be challenging. In fact, van Riet and colleagues, showed that approximately 50% of acute triceps tendon ruptures were missed on the initial examination. Viegas described a test similar to the Thompson test used for the diagnosis of Achilles tendon ruptures. In this variation, the patient is placed prone with the affected arm hanging over the edge of the examination table. The triceps muscle belly is squeezed and if the tendon is intact, the elbow should extend slightly. If the elbow fails to extend, the test is positive for a triceps tendon rupture.

Diagnostic imaging

In the case of a suspected triceps tendon rupture, plain radiographs should be obtained. In many patients, these images are normal. In the setting of preexisting tendinopathy, there are often enthesophytes present at the tip of the olecranon. These structures can fracture with a triceps tendon rupture. The flake sign is the presence of an avulsion fracture from the olecranon process and is felt to be pathognomonic of a triceps rupture ( Fig. 3 ). A recent systematic review showed presence of bony avulsion in 61% of patients with triceps tendon rupture.

Advanced imaging is usually obtained to confirm the presence of a triceps tendon rupture. For most practitioners, MRI is the modality of choice. Ultrasound examination can also be used to evaluate the integrity of the tendon. Both MRI and ultrasound examination are capable of distinguishing between partial and complete tendon injuries. ^, ^, A triceps tendon rupture is best visualized on sagittal images ( Fig. 4 ). A complete tear will be evident on T2-weighted images with high signal seen between the tendon and the olecranon. Chronic partial tears show an area of increased signal on T1-weighted or proton density images. Acute partial tears also show increased signal on T2-weighted images. Partial tears can involve the deep or superficial layers and are more common at the medial aspect of the tendon. ^, A recent study did find that MRI may overestimate the presence of full-thickness tears. Of the 3 surgically confirmed complete tears, MRI correctly reported a complete tear in all patients. Of the 6 partial tears confirmed at surgery, MRI correctly identified 4 tears. In 2 cases, MRI described a complete tear, but only a partial tear was noted at surgery.

Nonsurgical Treatment

The management of distal triceps tears is generally guided by tear location and functional extension strength of the extremity. Assessment of functional extension strength is important because complete anatomic ruptures do not necessarily cause full loss of function. If intact, the lateral triceps expansion or anconeus may compensate adequately for the loss of triceps function. The patient with complete anatomic rupture but with some function remaining should be identified and treated according to goals set specifically for that patient. Treatment decisions should be based on the patient’s medical and functional status on an individualized level. In general, any tear of less than 50% can be treated nonsurgically with satisfactory results. Tears of greater than 50% are treated nonsurgically in the sedentary person; however, in the active person, surgical intervention may be appropriate. ^, Complete tears are generally managed surgically. ^, ^,

Partial tears at the muscle belly, musculotendinous junction, and tendon insertion with insignificant loss of extension strength can be managed nonsurgically. Tears of the triceps occurring within the muscle or musculotendinous junction are thought to have good healing potential and are generally treated conservatively. Muscle belly tears tend to heal with scar tissue rather than with newly regenerated muscle. Outcomes are relatively similar with these tears regardless of treatment. Thus, even complete tears within the muscle belly can typically be managed nonsurgically.

Good results have been reported with nonsurgical management, with published studies indicating a return to preinjury level of function. ^, ^, Mair and colleagues reported that of 10 professional football players with partial tears, 6 healed with nonsurgical treatment and experienced no residual pain or weakness. Three players were treated with bracing for the remainder of the season, after which they received surgical treatment to correct residual pain and weakness. One player sustained a complete rupture on return to play despite bracing.

Nonsurgical management routinely includes a brief period of splint immobilization (3–4 weeks) at 30° of flexion. This period is followed by progressive elbow flexion mobilization. Progression of elbow motion is allowed as tolerated after 4 weeks. ^, ^, ^, ^, ^,

Surgical Treatment

Almost all complete triceps tendon injuries should be managed with surgical repair. ^, The exceptions include very low demand patients or those not medically fit for surgery. Partial tendon injuries that are high grade (involving >50% of the tendon), associated with tendon retraction and extension weakness, or that have failed conservative treatment also benefit from surgical repair by decreasing pain and improving strength. These indications are particularly applicable in active individuals and athletes.

Early primary repair is appropriate for acute, complete triceps tear at the tendinous insertion with significant loss of triceps strength. Ideally, repair should be performed within 2 to 3 weeks, although primary repair has been described as late as 8 months after injury. A 2003 study showed that repair is most successful when performed in the first 3 weeks, with all patients regaining four-fifths manual strength, but a mean of 10° of terminal extension was lost.

A variety of surgical techniques have been described for triceps tendon repair. There is no clear superior technique in terms of clinical outcomes, but each has theoretic advantages. All techniques focus on reattachment of the torn central tendon to the olecranon. In addition, any disruption of the lateral triceps expansion should be addressed because this strategy helps to augment the primary repair.

One of the historically popular repair techniques involves the use of the Bunnell or Krackow whipstitch technique, which includes placement of nonabsorbable sutures through the tendon. The sutures are then passed through transosseous drill holes in the olecranon and are tied over a bone bridge ( Figs. 5 and 6 ). ^, The transosseous drill hole technique can also be used in skeletally immature patients. Alternatively, the triceps may be reattached with the use of suture anchors placed within the olecranon in a single or double row configuration. ^, ^, ^, With both of these techniques, side-to-side sutures are recommended to reinforce the edges of the repair. Other repair techniques found in the literature include direct tendon repair to a periosteal flap raised from the olecranon. ^,