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Medial Collateral Ligament of the Elbow

- Anatomy:
    - humeral origin of MCL lies posterior to axis of elbow flexion, creating cam effect;
           - hence, anterior fibers are stressed in extension & posterior fibers are stressed in flexion; 
    - anterior oblique, posterior oblique ligament, & small transverse ligament are 3 major portions of the elbow MCL;
           - anterior oblique ligament:
                   - primary stabilizer of elbow for functional ROM from 20-120 deg;
                   - significant portion of anterior band inserts near coronoid process and that significant MCL instability may
                           result from low coronoid process frx;
           - posterior oblique ligament:
                  - weak fan-shaped thickening of capsule, which is absent in primates;
                  - it arises at the posterior aspect of the medial epicondyle and inserts over the olecranon;
                  - it forms the floor of the cubital tunnel;
                  - this functions as a secondary stabilizer only at 30 deg of flexion; 
    - references:
           - Experimental elbow instability after transection of the medial collateral ligament
           - Biomechanics of elbow instability: the role of the medial collateral ligament.
           - Valgus stability of the elbow. A definition of primary and secondary constraints.
           - Biomechanical study of ligaments around the elbow joint.
           - Valgus stability of the elbow.
           - The Medial Collateral Ligament of the Elbow Is Not Isometric: an in vitro biomechanical study. 
           - Effect of the Posterior Bundle of the Medial Collateral Ligament on Elbow Stability 

 - Function: 
    - primary medial stabilizer of the flexed elbow joint;
    - in full extension MCL provides about 30 % of stability versus about 54% in 90 deg flexion (some estimate that ligament provides over 70%);
    - in contrast the radial head is an important secondary stabilizer in extension as well as flexion (provides 30-33% of stability);
    - 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 elbow, and may produce subluxation or dislocation;
    - MCL laxity most often results from repetitive valgus loading such as throwing
    - Role of MCL in Flexion Contracture of the Elbow: (see Flexion Contracture of the Elbow)
           - Release of the medial collateral ligament to improve flexion in post-traumatic elbow stiffness.
           - The medial approach for operative release of post-traumatic contracture of the elbow.

- Radiographs:
    - w/ MCL tear, look for abnormally wide joint space on the medial side;

- MRI:
    - w/ MCL tear, MRI (T2) images will show focal discontinuity of the ligament and joint fluid extravasation; 
    - MRI arthrography is the imaging study of choice for evaluation of medial collateral ligament injuries.
    - references: 
           -  Noncontrast MR imaging and MR arthrography of the ulnar collateral ligament of the elbow: prospective evaluation of two-dimensional pulse sequences for detection of complete tears.
           - Anterior bundle of ulnar collateral ligament: evaluation of anatomic relationships by using MR imaging, MR arthrography, and gross anatomic and histologic analysis.
           - Medial epicondylitis and cubital tunnel syndrome in the throwing athlete
           - Nonoperative Treatment of Ulnar Collateral Ligament Injuries in Throwing Athletes    

- Chronic MCL Laxity: 
    - power point slide show
    - often occurs from chronic repetive throwing which stresses the elbow in mid-flexion;
            - in about 30 deg of flexion, neither the radial head nor the anterior joint capsule provide significant resistance to valgus stress, which leaves
                     the MCL vulnerable to overload;
    - posteromedial olecranon impingement occurs which results in inflammation, chondral injury, and eventual osteophytes and loose body formation;
            - this condition is demonstrated by posteromedial elbow tenderness as a valgus force is applied against the fully extended elbow;
    - osteochondrosis of medial epicondyle
            - in children the medial epicondylar physis is weaker than the MCL complex and chronic injury to this apophysis results
                      growth disturbances and overgrowth;
    - diff dx: medial epicondylitis
    - in the report by Rettig AC et al (2001), the authors evaluated 31 throwing athletes with ulnar collateral ligament injuries (from 1994 to 1997);
          - the authors sought to determine what percentage of athletes could return to their sport without surgical intervention;
          - nonop treatment included a minimum of 3 months’ rest w/ rehab exercises, allowed 42% of the athletes (N = 13) to return to
                   their previous level of competition;
          - those who returned to sports did so at an average of 24.5 weeks after diagnosis;
    - surgical repair:
            - w/ proximal tears, consider reattachment thru drill holes in medial epicondyle;
            - w/ intra-substance tears consider augmentation w/ palmaris longus;
            - references:
                   -  Traumatic Valgus Instability of the Elbow: Pathoanatomy and Results of Direct Repair          



Clinical Follow-up of Professional Baseball Players Undergoing Ulnar Collateral Ligament Reconstruction Using the New Kerlan-Jobe Orthopaedic Clinic Overhead Athlete Shoulder and Elbow Score (KJOC Score)


Textbook: Operative Treatment of Elbow Injuries: 

Surgical management of chronic medial elbow instability.

Reconstruction of the ulnar collateral ligament in athletes.

Medial instability of the elbow in throwing athletes: Treatment by repair or reconstruction of the ulnar collateral ligament

Evidence of Subclinical Medial Collateral Ligament Injury and Posteromedial Impingement in Professional Baseball Players.

Elbow Medial Ulnar Collateral Ligament Insufficiency Alters Posteromedial Olecranon Contact.

A biomechanical comparison of four reconstruction techniques for the medial collateral ligament-deficient elbow.

The Modified Docking Procedure for Elbow Ulnar Collateral Ligament Reconstruction. 2-Year Follow-up in Elite Throwers.

Biomechanical Evaluation of 2 Techniques for Ulnar Collateral Ligament Reconstruction of the Elbow.

Medial Ulnar Collateral Ligament Reconstruction of the Elbow in Throwing Athletes.

Traumatic Valgus Instability of the Elbow: Pathoanatomy and Results of Direct Repair

Outcome of Ulnar Collateral Ligament Reconstruction of the Elbow in 1281 Athletes. Results in 743 Athletes With Minimum 2-Year Follow-up