Tri-County Orthopaedics

In this issue...

May 18, 2005

Ligament Injuries of the Elbow

The following article was published by Dr. Andrew Willis in the American Association of Orthopaedic Surgeons (AAOS) Residents’ E-Letter in February 2004

Andrew A. Willis, M.D.
Tri-County Orthopaedic & Sports Medicine
160 East Hanover Ave, Morristown, N.J. 07962
Tel: (973) 538-2334 / Fax: (973) 538-4081
www.tri-countyortho.com

Medial Collateral Ligament Injuries of the Elbow

The medial collateral ligament complex is an important soft tissue restraint to valgus stress at the elbow joint. The ligament occupies the central two thirds of the anteroinferior surface of the medial epicondyle, just posterior to the axis of the elbow, and consists of three anatomic components: the anterior bundle, the posterior bundle, and the transverse oblique bundle. The anterior bundle is a well defined structure that takes origin from the inferior aspect of the medial epicondyle and inserts about the sublime tubercle of the ulna. It is the strongest and stiffest portion of the MCL with an average load to failure of 260 N. The anterior bundle can be further subdivided into two functionally separate anterior and posterior bands, which tighten in a reciprocal fashion during flexion and extension. The deep middle fibers of the anterior bundle are isometric and are easily identifiable between the anterior and posterior bands. The fan-shaped posterior bundle is a weaker and less distinct thickening of the posterior capsule that originates on the posterior portion of the medial epicondyle and forms the floor of the cubital tunnel on its way to inserting on the ulna, proximal and posterior to the sublime tubercle. The transverse bundle is comprised of fibers running along the medial joint capsule from the tip of the olecranon to the medial ulna, just distal to the coronoid. It is variably present and contributes little to elbow stability as it does not cross the elbow joint.

Biomechanically, the anterior bundle is the most important portion of the MCL, contributing 55% to 70% to valgus stability. A recent cutting study has demonstrated that the anterior band is the primary restraint to valgus stress from 30 to 90 degrees of flexion, and becomes a secondary restraint with further flexion. The posterior band is a secondary restraint at lesser degrees of flexion, but becomes functionally more important between 60 degrees and full flexion. The posterior bundle plays a minor role in valgus stability acting as a secondary restraint at 30 degrees of elbow flexion. Bony anatomy, particularly the olecranon/olecranon fossa articulation, provides primary stability at less than 20 degrees of elbow flexion or greater than 120 degrees of flexion.

Injury to the medial collateral ligament is most commonly the result of acute or chronic trauma, but can also be iatrogenic, secondary to excessive medial epicondylectomy for cubital tunnel syndrome. Acute MCL ruptures that occur with elbow dislocation generally heal well and seldom result in functional impairment, most likely due to the limited valgus stress imposed on the elbow during normal activities of daily living. The vast majority of MCL injuries that present with symptomatic valgus instability are associated with chronic overuse in the overhead or throwing athlete. Baseball players and in particular pitchers, are the athletes most commonly affected. Athletes that participate in sports that require similar overhead motion such as football, volleyball, tennis, or javelin can likewise be affected. Throwing places repetitious high valgus stress on the medial aspect of the elbow. The late cocking and early acceleration phases produce concentrated force on the medial elbow, in a position stabilized nearly exclusively by the anterior band of the MCL. These forces may exceed the tensile strength of the ligament, producing microscopic tears. Repetitive microtrauma may eventually lead to ligament attenuation or failure. Large valgus loads with rapid elbow extension in an elbow with medial ligamentous insufficiency can lead to degenerative or traumatic arthritis, with formation of osteophytes and loose bodies posteriorly and medially. This phenomenon has been termed “valgus extension overload syndrome.”

Evaluation of elbow MCL injuries is based on a careful history and physical examination. Patients with acute ruptures of this ligament usually present with a history of a “pop” followed by pain and swelling on the medial aspect of the elbow. Those with chronic valgus insufficiency typically present complaining of a history of pain and tenderness over the medial aspect of the elbow that is aggravated during and after throwing activities. Frequently, the thrower will recall a prodromal period of seemingly innocuous medial pain during the acceleration phase (85%) or deceleration phase (25%) of throwing that is followed by a sudden episode of acute pain that may or may not be associated with a popping sensation. Subsequently, these patients are unable to throw more than 50% to 75% of their normal level. Secondary ulnar nerve symptoms may be present in up to 40% of these patients due to ulnar nerve compression by inflammation within the cubital tunnel or to traction on the nerve from repeated valgus loading.

Valgus instability of the elbow can be assessed on physical examination using several different maneuvers. The manual valgus stress test is performed with the patient seated and the hand and wrist held securely between the examiner’s forearm and trunk. The patient’s elbow is flexed beyond 25 degrees to unlock the olecranon from its fossa and the MCL is palpated while simultaneously applying a valgus stress. A positive test is characterized by local pain, tenderness, and end-point laxity. The milking maneuver is a sensitive test for damage to the MCL and is helpful in diagnosing ligament tears in continuity. This test is performed by pulling on the patients thumb with the patient’s forearm supinated, shoulder extended, and the elbow flexed to 90 degrees. A positive test is characterized by localized medial elbow pain and a subjective feeling of apprehension and instability as a result of the valgus force generated on the flexed elbow. The moving valgus stress test is performed by applying a valgus stress to the elbow in the flexed position and then quickly extending the elbow. A positive test produces medial pain typically between 120 degrees to 70 degrees of flexion as a result of shear stress on the MCL. The valgus extension overload test is used to detect the presence of characteristic degenerative or traumatic arthritic changes that can result from chronic valgus stress to an elbow with medial instability. The examiner stabilizes the humerus with one hand and with the opposite hand, pronates the forearm, and applies a valgus force while quickly maximally extending the elbow. A positive test result reproduces pain posteromedially around the olecranon as a result of osteophyte impingement.

Imaging modalities can be useful adjuvants to the physical examination. Standard radiographs may identify ossification within the MCL, loose bodies in the posterior compartment, olecranon and condylar hypertrophy, or osteochondrotic lesions of the capitellum. Valgus stress radiographs may show excessive medial joint line opening compared with the contralateral elbow. Currently, MRI or CT arthrogram is the imaging modalities of choice for evaluating the MCL. While these tests have been shown to have 100% sensitivity for diagnosing complete ruptures of the MCL in some studies, poorer results have been reported for the detection of partial tears.

Treatment options for patients with an MCL injury include rehabilitation, repair, and reconstruction with free tendon graft. Rest and nonoperative treatment, including nonsteriodal anti-inflammatory medications, alternating ice and heat, and other physical therapy modalities applied in the early symptomatic period, may arrest the progression of instability and allow return to full function, especially in the low-demand noncompetitive or nonthrowing athlete. Therapy should be directed at strengthening the scapular stabilizers and the rotator muscle groups of the ipsilateral shoulder as well as the medial sided flexor-pronator muscles of the forearm. MCL deficient patients who are involved in high-performance throwing sports, however, do not respond well to nonoperative management with only 42% of patients being able to return to their preinjury level of throwing. Surgical intervention is most commonly indicated in the overhead throwing athlete with a complete tear of the anterior bundle of the MCL who wishes to return to competitive throwing sports or in cases of partial ligament tears in which high-demand throwing athletes have failed a comprehensive rehabilitation program. Occasionally, operative management is indicated in nonthrowing athletes or heavy laborers who remain symptomatic despite nonoperative management.

Direct repair of the MCL is reserved for the rarely encountered acute ligamentous avulsions from the humeral origin or coronoid insertion related to a defined traumatic event. Reconstruction of the MCL has demonstrated superior results in the throwing athlete compared with primary repair for ruptures that occur in association with an attenuated ligament. Jobe and associates in 1986 were the first to describe a reconstructive technique for MCL injuries in which the anterior band of the MCL was reconstructed by placing a free-tendon graft in a figure-eight fashion in bone tunnels in the ulna and medial epicondyle of the humerus and suturing the graft to itself. A submuscular ulnar nerve transposition was routinely performed, yet a high incidence of postsurgical ulnar neuritis was reported. Several modifications have since been described. Azar and Andrews elevate but do not detach the flexor-pronator mass and perform a subcutaneous ulnar nerve transposition. Thompson, Jobe, and Yocum now perform a muscle splitting approach to the MCL without routine ulnar nerve transposition. Rohrbough and Altchek perform a muscle splitting approach through the safe zone in the flexor-pronator mass with a single humeral tunnel and Krackow stitch tendon fixation over a bone bridge called the “docking procedure.” They do not routinely transpose the ulnar nerve. Commonly used tendon grafts include palmaris longus, plantaris, and hamstring tendon autografts.

Recently, arthroscopy has been introduced as a useful adjunct in the assessment and treatment of MCL injury. Visualizing pathologic joint opening of the medial aspect of the ulnohumeral joint while a valgus stress is applied can be helpful in confirming MCL injury. Arthroscopy can also be useful in addressing concomitant pathology associated with chronic symptomatic valgus instability such as intra-articular loose bodies or poster medial osteophyte impingement lesions.

Properly performed reconstruction of the MCL has proven to be a reliable and safe procedure. The primary outcomes measure for MCL reconstruction has been the return, or failure to return, to the player’s previous level of competition. Based on the literature, a competitive thrower can generally expect a 70% to 90% chance of returning to their previous level of competition.