Elbow Collateral Ligament Insufficiency

Anatomic constraints on elbow instability

There are three primary static constraints on elbow instability, as follows:

• Ulnohumeral joint
• MCL - This ligament comprises three bundles: the anterior bundle, which is tight in extension and loose in flexion-restraint to valgus rotation ^[24] ; the posterior bundle, which is tight in flexion and loose in extension; and the transverse bundle, which has a variable presence
• LCL, especially its ulnar part - The LCL complex (which is characterized by a large amount of variation) includes the radial collateral ligament (RCL), the lateral UCL (LUCL), the accessory lateral collateral ligament (ALCL), and the anular ligament (AL)

There are four secondary restraints on elbow instability, as follows:

• Radial head and capsule - The anterior capsule prevents hyperextension of the elbow
• Common flexor and extensor origins
• Flexor-pronator and extensor-supinator groups (stabilizing against valgus and varus stress, respectively)
• Dynamic stabilizers - These are the muscles that cross the joint and provide compressive forces at the articulation (anconeus-triceps, brachialis)

Both the MCL and the LCL are strong fan-shaped thickenings of the fibrous joint capsule. These ligaments prevent excessive abduction and adduction of the elbow joint. The AL wraps around the radial head and holds it tight against the ulna.

Medial collateral ligament

The humeral origin of the MCL lies posterior to the axis of elbow flexion, creating a cam effect; hence, anterior fibers are stressed in extension, and posterior fibers are stressed in flexion. The MCL has the following three major portions (see the image below):

• Anterior oblique ligament
• Posterior oblique ligament
• Transverse ligament

The anterior oblique ligament is the primary stabilizer of the elbow for functional range of motion (ROM) from 20º to 120º. It arises from the anteroinferior surface of the medial epicondyle and inserts at the sublimis tubercle, adjacent to the joint surface. The anterior bundle inserts at an average distance of 18.4 mm dorsal to the coronoid tip; thus, the attachment would be disrupted only in Regan and Morrey type III fractures of the coronoid.[25]

The anterior oblique bundle has two subportions, anterior and posterior. The anterior band is the primary restraint to valgus rotation at 30º, 60º, and 90º of flexion and is a coprimary restraint at 120º; it is more likely to be injured with the elbow in extension. The posterior band is the coprimary restraint at 120º; it is more likely to be injured in flexion (though injury to this band usually occurs along with injury to the anterior band).

The posterior oblique ligament is a weak fan-shaped thickening of the joint capsule, which arises at the posterior aspect of the medial epicondyle and inserts over the olecranon; it forms the floor of the cubital tunnel and functions as a secondary stabilizer only at 30º of flexion.

The transverse ligament is a constant anatomic structure that is intra-articularly visible within the lower part of the medial joint capsule; it strengthens the articular joint capsule and contributes to elbow stability.

The MCL is the primary medial stabilizer of the flexed elbow joint. In full extension, it provides about 30% of stability, versus about 54-70% in 90º flexion. The radial head is an important secondary stabilizer in extension, as well as in flexion. After excision of the radial head alone, there is a 30-33% loss in valgus stability of the elbow, which does not significantly improve even after replacement with a silicone rubber radial head.

Resection of the anterior band of the MCL will result in gross instability, except in full elbow extension. Resection of both the MCL and the radial head results in gross instability of the elbow and may produce subluxation or dislocation of the elbow. The anterior bundle of the MCL is tested with the elbow in 90º of flexion.

Lateral collateral ligament and anular ligament

Anatomically, the LCL consists of a ligamentous expansion proceeding down from the lateral epicondyle to the ulna (a major expansion, which inserts into supinator crest of the ulna) and also sends expansions down to the AL and the radius.

The LCL has a greater role with increased flexion of the elbow. LUCL deficiency leads to posterolateral rotatory instability. Additional deficiency of the RCL results in dislocation of the elbow.

The ECU (extensor carpi ulnaris) tendon and the supinator tendon merge with the LCL and resist posterolateral instability.

UCL injuries can manifest as acute ligament tears following a single valgus stress or as overuse sprains following repetitive valgus overloads. Repetitive medial stress can also cause attenuation and microstretching of the UCL complex, causing instability over time.

Maximal MCL stress occurs when the elbow remains flexed between 60º and 75º and the wrist begins to cock in preparation for the throw in the late cocking phase of throwing, as well as in the acceleration phase, when maximal humeral external rotation occurs.

The common pathway of posterolateral instability includes the following:

• Extension overload - Medial UCL insufficiency alters contact area and pressure between the posteromedial trochlea and olecranon and helps explain the development of posteromedial osteophytes
• Triceps muscle strain
• Avulsion fracture tip of olecranon
• Olecranon hypertrophy
• Loose bodies in the olecranon fossa
• Tears of brachialis and anterior capsule
• Fixed flexion contracture
• Posterolateral instability

Recurrent microtrauma of the skeletally immature elbow joint in children can lead to Little Leaguer's elbow, a syndrome that encompasses the following:

• Delayed or accelerated growth of the medial epicondyle (medial epicondylar apophysitis)
• Traction apophysitis (medial epicondylar fragmentation)
• Medial epicondylitis

With posterior dislocation of the elbow joint, dislocation begins on the lateral side of the elbow and progresses to the medial side in three stages, as follows:

• Stage 1 - Partial or complete disruption of the LCL (mainly its ulnar part); this results in posterolateral rotatory subluxation, which can reduce spontaneously
• Stage 2 - Incomplete posterolateral dislocation, in which the concave medial edge of the ulna rests on the trochlea
• Stage 3a - Disruption of all of the soft tissues around, and including, the posterior part of the MCL, leaving the important anterior band, which provides stability if the forearm is kept in pronation, to prevent posterolateral rotatory subluxation
• Stage 3b - Disruption of the entire MCL, which makes the elbow unstable after reduction
• Stage 3c - Stripping of soft tissue from the entire distal aspect of the humerus, which makes the elbow unstable, even in 90º flexion

The two most common causes of elbow instability are sports (commonly chronic) and trauma (acute onset, as with ligamentous injuries in elbow dislocation).

During the throwing motion, high loads of valgus stress on the elbow joint results in tension on the medial structures (ie, medial epicondyle, medial epicondylar apophysis, and MCL complex) and compression of the lateral structures (ie, radial head and capitellum). Repeated MCL stress due to medial tension overload may result in MCL strain or rupture. This chronic injury may lead to development of ulnar traction spurs, deposition of calcium, and medial ligament instability.

Injuries associated with specific sports include the following:

• Golf - Medial epicondylitis of the trailing arm and lateral epicondylitis of the leading arm
• Racquet sports - Lateral epicondylitis with backhand
• Bowling - Medial epicondylitis
• Baseball and volleyball - Valgus stress of medial structures and compression of lateral structures
• Weight training - UCL strain and ulnar neuritis
• Canoeing and kayaking - Distal bicipital tendinitis
• Archery - Lateral epicondylitis of the bow arm
• Rock climbing - Distal bicipital and brachialis tendinitis
• Football - Valgus stress with throwing a pass

In a study of 72 professional baseball players who underwent arthroscopic or open elbow surgery, the most common causes of elbow symptoms were posteromedial olecranon osteophyte (65%), UCL injury (25%), and ulnar neuritis (15%). In the United States, the estimated incidence of all baseball-related overuse injuries is 2-8% per year (20-50% of these injuries occur in adolescents and school-age children).

The true worldwide incidence of sports-related injuries is not known, because a large number of athletes never seek medical care and because the statistical data are unavailable from a number of countries.[3]

In one study, the patients with posteromedial olecranon osteophytes had the highest rate of reoperation due to persisting symptoms, and patients who underwent only UCL reconstruction had a higher rate of return to play.[6] At an average of 3.3 years after UCL reconstruction with use of the docking technique, 92% of patients had an excellent result and had returned to, or exceeded, their previous level of play. The docking technique may offer better results than Jobe's original procedure while minimizing the associated risks.

Watson et al conducted a systematic review comparing clinical outcomes of the Jobe, modified Jobe, docking, modified docking, Endobutton, and interference screw techniques for UCL reconstruction in elite overhead athletes.[26]  The review included 21 studies that reported on 1368 patients. The investigators concluded that UCL reconstruction utilizing the docking technique results in a significantly higher rate of return to play and a lower complication rate in comparison with the Jobe and modified Jobe techniques.

Erickson et al, in a study aimed at determining whether clinical outcomes and rates of return to sport after UCL reconstruction differed according to graft choice, surgical technique, or other variables, found that both docking and double-docking reconstruction yielded excellent clinical outcomes, with no significant differences between the techniques.[27] Graft type also did not significantly affect outcome scores. The incidence of complications was lower with the double-docking technique than with the docking technique.

Patients with posterolateral rotatory instability often remember a distinct traumatic event, most frequently a posterior dislocation. The athlete has a sense of instability and reports a snapping sensation that causes pain during throwing.

Patients with olecranon impingement syndrome often complain of posterior elbow pain with locking or snapping when throwing. The pain is worst when the elbow is extended. Throwers often complain of loss of velocity and control.

Patients with an anterior capsule strain present with anterior elbow pain, which often is aggravated by repetitive hyperextension and is not affected by elbow flexion.

Patients with a medial collateral ligament (MCL) sprain experience referred pain down the arm into the little finger and ring finger, which mimics the symptoms of cubital tunnel syndrome. A more common reason for this condition is ligament laxity in C6 and C7 or in the ulnar collateral ligament (UCL), not a pinched nerve.

MCL insufficiency manifests as medial elbow pain with laxity to valgus stress.

Medial epicondylar apophysitis is caused by repetitive valgus stress and generally manifests as progressive medial pain, decreased throwing effectiveness, and decreased throwing distance.

Medial epicondyle fracture manifests as point tenderness and swelling over the medial epicondyle, often with an elbow flexion contracture greater than 15°.

Neurologic injuries such as C8-T1 radiculopathy and ulnar neuritis, though uncommon in children, can manifest as medial elbow pain and should be included in the differential diagnosis.

A number of clinical diagnostic procedures are helpful in establishing elbow instability and collateral ligament injury.

In the valgus stress test, the elbow is flexed to 20-30º, and abduction or valgus force is then applied at the distal forearm.[13]

The “milking maneuver” is performed with the arm at 70°, with the valgus force applied by supporting the elbow and tractioning the thumb.

With the moving valgus stress test (the most sensitive of these procedures), pronation, valgus of the forearm, and internal rotation of the shoulder cause pain at 70-120° flexion arc (see the image below).

In the lateral compression test, the examiner applies valgus stress while going from flexion to extension and back. This is repeated in the radioulnar joint in various degrees of pronation and supination. One hand is just above the elbow joint, and the other is placed on the wrist.

In the varus stress test, the elbow is flexed to 20-30º, and the patient's arm is then stabilized with one of the examiner's hands placed at the medial distal humerus (elbow) and the other above the patient's lateral distal radius (wrist). An adduction or varus force is applied at the distal forearm by the examiner to test the radial collateral ligament (RCL).

In the pivot shift test, the patient lies supine with the arm overhead. The elbow is supinated, and a valgus force and axial force are applied to the elbow. The patient may complain of pain or apprehension. Then, starting in extension, the elbow is flexed with a reduction “clunk” occurring, typically at 40-70° of flexion.

The white blood cell count (WBC), the erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) activity should be assessed to rule out any active inflammation.

Radiography

Standard radiographs of the elbow include the anteroposterior (AP) view and the true lateral view. Special views include the following:

• Axial projections to evaluate the olecranon fossa
• Oblique views to assess the radial head
• Stress views to evaluate joint stability (>5 mm abnormally wide joint space on the medial side, with the elbow flexed to 30° in a medial collateral ligament [MCL] tear)

Ultrasonography

Ultrasound examination commonly shows the following:

• Widening of the medial joint space
• Lateral shift of the proximal part of the ulna
• Deformity of the contour of the ulnar collateral ligament (UCL)
• Osteophyte formation on the distal-medial corner of the trochlea

Magnetic resonance imaging, with or without arthrography

Magnetic resonance imaging (MRI) can be helpful in identifying soft-tissue masses, articular cartilage anatomy, ligament ruptures, and chondral defects.[28]

With MCL tears, T2-weighted MRI will show focal discontinuity of the ligament and joint fluid extravasation.

High-resolution MRI of the elbow, using a microscopy surface coil with a 1.5-Tesla (1.5T) clinical machine, is a promising method for accurately characterizing the normal anatomy of the elbow and depicting its lesions in detail (eg, partial MCL injury or a small avulsion of the medial epicondyle).

MCL abnormalities such as thickening, signal heterogeneity, or discontinuity consistent with posteromedial impingement can be seen in asymptomatic throwers' elbows. These baseline findings must be considered when MRI is being used in making treatment decisions. MCL thickening and posteromedial subchondral sclerosis are more consistent findings of posteromedial impingement seen in throwers' elbows.

Other imaging studies

Computed tomography (CT) is useful for delineating complex osseous anatomy. CT arthrography may be useful for defining capsular defects (extracapsular contrast extravasation) and loose bodies. Bone scanning is sensitive but not specific for differentiating between stress fractures, healing fractures, infections, and tumors.

Although other studies can be helpful in confirming a diagnosis (eg, a positive manual pivot shift test result), they are somewhat insensitive. Thus, clinical judgment should prevail in making treatment decisions.

Electromyography (EMG) and nerve conduction studies are used to evaluate suspected nerve compression syndromes.

 

Surgical reconstruction is indicated in the following patients:

• Overhead-throwing athletes with acute complete medial collateral ligament (MCL) ruptures or chronic instability for more than 6 months, with medial elbow pain that prevents throwing and is refractory to conservative treatment
• Patients in whom preoperative standard noncontrast magnetic resonance imaging (MRI) demonstrates medial ulnar collateral ligament (UCL) injury
• Patients with clinically apparent medial UCL (MUCL) insufficiency
• Unstable reduction after traumatic fracture dislocation of the elbow joint

Relative contraindications for surgical treatment include the following:

• Medical contraindication for surgery
• Patient noncompliance
• An elbow joint that is stable after closed reduction through a functional (30-130°) range of motion (ROM), with minimally displaced fractures following fracture dislocations of the elbow

Most symptomatic conditions of the overhead athlete can initially be treated conservatively. Any thrower who is experiencing medial elbow pain should refrain from pitching until he or she has had a thorough evaluation; a past history of medial elbow pain is a risk factor for fracture of the medial epicondyle. Nonsteroidal anti-inflammatory drugs (NSAIDs) may help relieve the pain and control the inflammatory reaction.

There is no evidence that the results of surgical repair of the ligaments are any better than those of nonsurgical treatment in patients with medial or both lateral and medial laxity of the elbow following nonfracture dislocations.

Platelet-rich plasma

Several studies have shown that platelet-rich plasma (PRP) injection can be a valuable component of nonoperative management in throwing athletes with elbow collateral ligament injuries.

Dines et al retrospectively evaluated the effect of PRP injections in 44 baseball players with partial UCL tears (mean age, 17.3 years; range, 16-28), of whom 16 had a single injection, six had two, and 22 had three.[29] At follow-up (mean, 11 months after injection), 15 of the 44 patients (34%) had an excellent outcome, 17 had a good outcome, two had a fair outcome, and 10 had a poor outcome. Mean time from injection to return to throwing was 5 weeks; mean time to return to competition was 12 weeks (range, 5-24 weeks). There were no injection-related complications.

Deal et al reported a case series of 25 throwing athletes with partial MUCL tears who were treated with two leukocyte-rich PRP injections, bracing, physical therapy, and a structured return-to-throwing protocol.[30]  Of the 25 patients, 23 were diagnosed with primary grade 2 MUCL injuries, and 22 of the 23 (96%) demonstrated stability of the MUCL after treatment and returned to play at the same or higher level of competition without further intervention. Two of the 25 had undergone prior surgery; they remained unstable and symptomatic after this regimen, did not have complete reconstitution of the ligament on subsequent MRI, and required surgical reconstruction of the MUCL.

Postreduction assessment of stability

After reduction of a dislocated elbow, the elbow will generally be stable in 90º or more of flexion. If instability occurs in 30º of flexion, the forearm should be placed in maximum pronation, which maximizes the stress on the MCL and reduces the posterolateral subluxation. If there is increased stability in pronation, the elbow should be placed in a cast brace with the elbow in pronation.

In cases where conservative treatment is unsuccessful, surgical intervention is indicated.[3, 5, 6, 8, 9, 19, 20, 21, 22, 23, 31]

Choice of operative approach

Direct MCL repair is commonly used in acute ligamentous avulsions from the humeral origin (most commonly) or the sublime tubercle. Graft reconstruction is commonly performed with autologous grafts (palmaris longus, plantaris, 3.5-mm medial strip of Achilles, or hamstrings) and occasionally with allografts. The palmaris longus tendon, the most frequently used graft for elbow ligament reconstruction, is similar in strength to the anterior bundle of the MCL (AMCL): 357 N vs average failure load of 260 N.

No difference has been observed between single-strand and double-strand repair techniques. (See the images below.)

MCL reconstruction is carried out by several means. The strengths achievable with four commonly practiced methods relate to the strength of an intact ligament as follows:

• Intact ligaments are three times stronger than docking reconstructions
• Docking reconstructions and Endobutton reconstructions are equally strong
• Endobutton reconstructions are stronger than interference screw reconstructions
• Interference screw reconstructions are stronger than figure-eight reconstructions

However, the use of bioabsorbable interference screw fixation has resulted in less valgus angle widening in response to early cyclic valgus load than the use of the docking technique. Hence, the optimal fixation method for a single-strand MCL reconstruction may require improved interference screws or a modified Endobutton procedure.

Lateral collateral ligament (LCL) repair and reconstruction for posterolateral rotatory instability of the elbow using a tendon graft seem to provide better results than direct ligament repair, and the results do not seem to deteriorate with time. In primary cases such as traumatic fracture dislocation of the elbow, it usually is not necessary to employ tendon grafts or to perform ligament augmentations. On the grounds that the anconeus is a potential posterolateral stabilizer of the elbow in posterolateral elbow instability, an anconeus-sparing minimally invasive approach has been suggetsed as a means of restoring posterolateral stability.[32]

In posteromedial olecranon impingement, valgus angulation and varus-valgus laxity increase proportionately with the amount of olecranon resection. At 90° of elbow flexion and 3 N-m of applied torque, olecranon resections of 0, 4, and 8 mm produced varus-valgus laxity of 14°, 15°, and 18°, respectively. Hence, resections of the medial part of the olecranon for the treatment of posteromedial olecranon impingement in the throwing athlete should be limited to the osteophytes alone.

In general terms, surgery is indicated if one is unable to get stability of the LCL even with a hinged brace. If there is avulsion from the bone (usually off the humerus), repair is indicated.

If repair is impossible, reconstruction is indicated.

Preparation for surgery

Isometric fibers do not exist within the AMCL; however, nearly isometric areas are located on the lateral aspect of the attachment site of the AMCL on the medial epicondyle, near the anatomic axis of rotation. Hence, it has been postulated that these nearly isometric areas would be the ideal location for graft attachment during reconstruction of the AMCL.[33]

A tear of the deep layer of the UCL can result in symptomatic instability that is difficult to diagnose with conventional preoperative testing. These throwing-athletic patients present with persistent medial elbow pain, tenderness over the anterior bundle of the UCL, and pain with valgus stressing of the elbow.

MRI may be normal, and a computed tomography (CT) arthrogram may be negative for extracapsular contrast extravasation. A consistent finding in these patients could be a leak of contrast around the edge of the humerus or ulna, though the contrast is contained within the joint. On open medial elbow surgery, the UCL appears intact externally; but when the anterior bundle is incised, there would be a detachment of the undersurface of the ligament at the ulna or the humerus.

Operative details

UCL reconstruction is the current gold standard for managing UCL insufficiency; reconstruction techniques that have been described include the original and modified Jobe techniques as well as various docking techniques.[34]

The docking technique for UCL reconstruction involves a muscle-splitting approach to the ligament that spares the flexor origin. It also involves the use of one hole in the medial epicondyle rather than three, avoids the need to transpose the ulnar nerve, and simplifies the method of graft-tensioning prior to fixation.[6]

A systematic review and meta-analysis (four studies; 92 elbows) by Erickson et al suggested that UCL repair could be an acceptable alternative to UCL reconstruction for treatment of UCL tears.[35] In this study, repair, as compared with reconstruction, yielded similar return-to-sport rates and clinical outcomes and a shorter time to return to sport. Khalil et al described an approach to primary repair of proximal ulnar collateral ligament ruptures in pediatric overhead athletes.[36]  

In traumatic fracture dislocation of the elbow, detachment of the LCL complex from the humerus is repaired with nonabsorbable sutures placed either through drill-holes in the bone or with suture anchors. The most important suture is the stitch placed in the center of rotation of the elbow laterally, located at the center of the capitellar circumference in the lateral condyle. Midsubstance tears of the LCL are occasionally seen and are repaired with No. 1 or 2 nonabsorbable sutures.

A split anconeus fascia transfer to reconstruct the LCL complex comprises a strip of anconeus fascia detached from its origin and split in line with its fibers down to its ulnar insertion. The superior segment is passed under the anular ligament (AL) to reconstruct the proper radial collateral ligament (RCL), while the inferior segment is used to reconstruct the lateral UCL (LUCL). A docking technique is used to secure the fascia to the isometric point on the lateral epicondyle. (See the images below.)

Thus, a local graft can be used for anatomic reconstruction without the associated morbidity of tendon harvest, especially when instability arises during surgery.

Before definitive closure, the elbow is examined for stability. The goal is concentric reduction with no observed posterior or posterolateral subluxation or dislocation through an arc of flexion.

Postoperative care includes the following:

• Lateral-side injuries - Treat/immobilize in pronation
• Medial-side injuries - Treat/immobilize in supination
• Combined injuries - Treat/immobilize in neutral rotation

Potential complications of surgical treatment include the following:

• Detachment of the origin of the flexor-pronator muscle group
• Requirement for transposition of the ulnar nerve owing to ulnar nerve symptoms
• Fracture of the medial epicondyle secondary to multiple drill holes
• Inadequate graft-tensioning during fixation of the graft
• Transient radial-nerve palsy after intra-articular injection of local anesthetic
• Decreased ROM with a variable degree of flexion contracture and loss of flexion

After MCL reconstruction, which is secured in supination, immobilize the elbow for 1 week, then start active ROM (AROM) for the shoulder, elbow, and wrist in a supination brace. After 6 weeks, begin resistance strengthening. Valgus stress should be avoided for 3 months.