Elbow Collateral Ligaments 

Elbow collateral ligament insufficiency is commonly seen in sports participants involved in overarm-throwing sports such as cricket, baseball, and tennis. Trauma and postdislocation injuries are other common causes of collateral ligament injury, which can occur on either side of the joint. An understanding of the normal anatomy is required for diagnosis and successful surgical reconstruction.^{[1, 2, 3, 4, 5, 6, 7, 8, 9]}

The elbow is one of the most congruous joints in the body. It consists of 3 articulations between the humerus, ulna, and radius within a capsule. The medial elbow collateral ligament resists valgus force and supports the ulnohumeral joint. The lateral ligament prevents rotational instability between the distal humerus and the proximal radius and ulna. See the image below.

Jobe et al first described double-strand reconstruction of the ulnar collateral ligament with use of a free tendon graft that was secured to the medial epicondyle and the proximal aspect of the ulna in a figure-eight fashion (see image below).^[3]

Several complications are associated with this procedure, such as detachment of the flexor-pronator muscle group, extensive drilling of the medial epicondyle, and transposition of the ulnar nerve. Studies have focused on techniques of ulnar collateral ligament reconstruction that minimize the potential for complications, particularly those related to the medial epicondyle and the ulnar nerve.^{[4, 5, 7, 8, 10, 11, 12, 13, 14, 15, 16]}

Medial elbow instability and posterolateral rotatory instability in overhead-throwing athletes are increasingly popular topics. The diagnosis and treatment have been the focus of much basic-science and clinical research. Methods to accurately diagnose elbow instability continue to evolve. Patient history, physical examination, and magnetic resonance imaging, as well as arthroscopic techniques for diagnosis and treatment, continue to play a vital role in differentiating between nonoperative and operative candidates.^{[17, 18, 19, 20, 21, 6, 22, 23]}

Frequency

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%), ulnar collateral ligament 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 unknown, because a large number of athletes never seek medical care and the statistical data are not available from various countries.^[1]

Two most common causes of elbow instability are sports (commonly chronic onset) and trauma (acute in occurrence, such as 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, medial collateral ligament complex) and compression of the lateral structures (ie, radial head, capitellum). Repeated MCL (medial collateral ligament) 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.

Sports and associated injuries

• Golf: Medial epicondylitis of trailing arm and lateral epicondylitis of 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: Ulnar collateral ligament strain and ulnar neuritis
• Canoeing and kayaking: Distal bicipital tendinitis
• Archery: Lateral epicondylitis of bow arm
• Rock climbing: Distal bicipital and brachialis tendinitis
• Football: Valgus stress with throwing a pass

Ulnar collateral ligament (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 medial collateral ligament (MCL) stress occurs when the elbow remains flexed between 60 and 75 º 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.

Common pathway of posterolateral instability

• Extension overload - Medial ulnar collateral ligament 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 (1) delayed or accelerated growth of the medial epicondyle (medial epicondylar apophysitis), (2) traction apophysitis (medial epicondylar fragmentation), and (3) medial epicondylitis.

Stages of posterior dislocation of the elbow joint: dislocation begins on the lateral side of the elbow and progresses to the medial side in 3 stages:

• Stage 1: Lateral collateral (mainly ulnar part) is partially or completely disrupted. 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: All of the soft tissues around, and including, the posterior part of the MCL are disrupted, leaving the important anterior band, which provides stability if the forearm is kept in pronation, to prevent posterolateral rotatory subluxation.
• Stage 3b: Entire MCL is disrupted, which makes the elbow unstable following reduction.
• Stage 3c: Entire distal aspect of the humerus is stripped of soft tissue, which makes the elbow unstable, even in 90 º flexion.

• Posterolateral rotatory instability: Patients often remember a distinct traumatic event, most often a posterior dislocation. The athlete has a sense of instability and reports a snapping sensation, which causes pain when throwing.
• Olecranon impingement syndrome: Patients often complain of posterior elbow pain with locking or snapping when throwing. Pain is the worst when the elbow is extended. Throwers often complain of loss of velocity and control.
• Anterior capsule strain: Patients present with anterior elbow pain, which often is aggravated by repetitive hyperextension and is not affected by elbow flexion.
• Medial collateral ligament sprain: Referred pain down the arm into the little finger and ring finger mimicking the symptoms of cubital tunnel syndrome (a more common reason for this condition is ligament laxity in the sixth and seventh cervical vertebrae or in the ulnar collateral ligament, not a pinched nerve).
• Medial collateral insufficiency: Manifests as medial elbow pain with laxity to valgus stress.
• Medial epicondylar apophysitis: 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°.
• Although uncommon in children, neurologic injuries such as C8-T1 radiculopathy and ulnar neuritis can manifest as medial elbow pain and should be included in the differential diagnosis.

Surgical reconstruction is indicated in patients with the following:

• 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; in overhead-throwing athletes.
• A preoperative standard noncontrast magnetic resonance image demonstrating medial ulnar collateral ligament injury.
• Clinically apparent medial ulnar collateral ligament insufficiency.
• Unstable reduction following traumatic fracture dislocation of elbow joint.

Elbow anatomy and biomechanics

Constraints to elbow instability

There are 3 primary static constraints:

• Ulnohumeral joint
• MCL (medial collateral): consists of 3 parts:

  • Anterior bundle: tight in extension and loose in flexion-restraint to valgus rotation^[24]
  • Posterior bundle: tight in flexion and loose in extension
  • Transverse bundle: variable presence
• LCL (lateral collateral ligament; especially the ulnar part of LCL)

Lateral collateral ligament (LCL) complex (large amount of variation)

• Radial collateral ligament (RCL)
• Lateral ulnar collateral ligament (LUCL)
• Accessory lateral collateral ligament (ALCL)
• Annular ligament (AL)

There are 4 secondary restraints

• Radial head, capsule (anterior capsule prevents hyperextension of elbow)
• Common flexor and extensor origins
• The flexor-pronator group stabilizes against valgus stress, and the extensor-supinator group stabilizes against varus stress
• Dynamic stabilizers are the muscles that cross the joint and provide compressive forces at the articulation.

  • Anconeus - triceps
  • Brachialis

Both the collateral ligaments (medial collateral and lateral collateral) are strong fan-shaped thickenings of the fibrous joint capsule. These ligaments prevent excessive abduction and adduction of the elbow joint. The annular ligament wraps around the radial head and holds it tight against the ulna.

Medial collateral ligament (MCL)

• Humeral origin of MCL lies posterior to axis of elbow flexion, creating cam effect; hence, anterior fibers are stressed in extension, and posterior fibers are stressed in flexion.
• Anterior oblique, posterior oblique, and small transverse ligaments are the 3 major portions of the MCL .
• The anterior oblique ligament is the primary stabilizer of the elbow for functional range of motion (ROM) from 20-120º. It arises from the anteroinferior surface of the medial epicondyle and inserts at the sublimis tubercle, adjacent to the joint surface. As a significant portion of the anterior band inserts near the coronoid process, MCL instability may result from low coronoid process fracture.
• Subportions of the anterior oblique bundle: Anterior band is the primary restraint to valgus rotation at 30, 60, and 90º of flexion and is a coprimary restraint at 120º; this band is more likely to be injured with the elbow in extension. Posterior band is the coprimary restraint at 120º; this band is more likely to be injured in flexion (but injury to this band usually occurs along with injury to the anterior band).
• Posterior oblique ligament: This 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.
• Transverse ligament: This 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.
• MCL is the primary medial stabilizer of the flexed elbow joint. In full extension, the MCL 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 and annular ligaments

• Anatomically, the lateral collateral ligament consists of a ligamentous expansion proceeding down from the lateral epicondyle to the ulna (major expansion, which inserts into supinator crest of the ulna) and also sends expansions down to the annular ligament and the radius.
• The lateral collateral ligament has a greater role with increased flexion of the elbow. Lateral ulnar collateral ligament deficiency leads to posterolateral rotatory instability. Additional deficiency of the radial collateral ligament results in dislocation of the elbow.
• The ECU (extensor carpi ulnaris) tendon and the supinator tendon merge with the LCL and resist posterolateral instability.

Following are the relative contraindications for the surgery:

• Medical contraindication to surgery
• Noncompliant patient
• The elbow joint is stable following closed reduction through a functional (30-130°) range of motion, with minimally displaced fractures following fracture dislocations of the elbow