Introduction
  • Attenuation or rupture of the ulnar collateral ligament of the elbow leading to valgus instability
  • Epidemiology
    • demographic
      • overhead athletes who place significant valgus stress on their elbows (baseball pitchers)
      • relatively uncommon in skeletally immature throwing athletes 
        • little leaguers elbow
          • is the more common cause of medial elbow pain with decreased throwing effectiveness and distance 
  • Pathophysiology
    • mechanism
      • acute trauma
        • often associated with a dislocation
      • overuse injury
        • biomechanical forces
          • microtrauma from repetitive valgus stress leads to rupture of the anterior band of the medial UCL
          • baseball pitchers place significant valgus stress on the elbow in the late cocking and early acceleration phase of throwing   
          • elbow valgus load increases with poor throwing mechanics and decreases with trunk-scapular kinesis, forearm pronation, dynamic flexor-pronator stabilization
          • valgus load is highest in the acceleration phase
      • iatrogenic
        • excessive olecranon resection places the MCL at risk
  • Associated conditions
    • traction-related ulnar neuritis
    • olecranon (posteromedial) impingement
    • elbow arthritis
Anatomy 
  • Medial collateral ligament (MCL)
    • MCL is also called ulnar collateral ligament (UCL)
    • MCL divided into three components
      • anterior oblique
        • strongest and most significant stabilizer to valgus stress  
        • courses from medial epicondyle to the sublime tubercle
        • nearly isometric
        • anterior and posterior bands give reciprocal function throughout elbow range of motion
          • posterior band is tight in flexion and anterior band is tight in extension
      • posterior oblique
        • demonstrates the greatest change in tension from flexion to extension 
        • tighter in flexion
      • transverse ligament
        • no contribution to stability
Presentation
  • History
    • acutely injuries may result in a "pop" and then sudden drop in velocity
  • Symptoms
    • decreased throwing performance
      • loss of velocity
      • loss of control (accuracy)
    • pain
      • medial or posterior elbow pain during late cocking and acceleration phases of throwing
      • many throwers also have posteromedial pain due to valgus extension overload felt during the deceleration phase
    • ulnar nerve symptoms
  • Physical exam
    • inspection
      • medial tenderness at or near MCL origin
        • posteromedial tenderness may be due to valgus extension overload
      • evaluate the integrity of the flexor-pronator mass
      • evaluate for cubital tunnel symptoms
    • provocative tests
      • valgus stress test
        • place elbow at 20 to 30 degrees (unlocks the olecranon), externally rotate the humerus, and apply valgus stress
        • 50% sensitive
      • milking maneuver
        • create a valgus stress by pulling on the patient's thumb with the forearm supinated and elbow flexed at 90 degrees
        • positive test is a subjective apprehension, instability, or pain at the MCL origin
      • moving valgus stress test post
        • place elbow in same position as the "milking maneuver" and apply a valgus stress while the elbow is ranged through the full arc of flexion and extension
        • positive test is a subjective apprehension, instability, or pain at the MCL origin between 70 and 120 degrees
        • 100% sensitive and 75% specific 
Imaging
  • Radiographs
    • recommended views
      • AP and lateral of the elbow
        • static x-rays are often normal
    • optional views
      • oblique views to evaluate the olecranon
      • gravity stress
        • may show medial joint-line opening >3 mm (diagnostic)
    • findings
      • assess for a posteromedial osteophyte (due to valgus extension overload)
  • MRI
    • views
      • best seen on coronal T2-image
    • findings
      • conventional MRI may identify a thickened ligament (chronic injury), calcifications, and tears
    • MR-arthrogram diagnostic 
      • can diagnosis full-thickness and partial undersurface tears
      • look for capsular "T-sign" with contrast extravasation
  • Dynamic ultrasound
    • can evaluate laxity with valgus stress dynamically
    • operator dependent
Treatment
  • Nonoperative 
    • rest and physical therapy
      • indications
        • first line treatment in most cases  
      • technique
        • 6 weeks of rest from throwing
        • initial physical therapy for flexor-pronator strengthening and improving throwing mechanics (after 6 weeks and symptoms have resolved)
        • progressive throwing program
      • outcomes
        • 42% return to preinjury level of sporting activity at an average of 24 weeks
  • Operative
    • MCL anterior band ligament reconstruction (Tommy John Surgery) 
      • indications
        • high-level throwers that want to continue competitive sports
        • failed nonoperative management in patients willing to undergo extensive rehabilitation
      • technique (see below)
        • reconstruction is favored over direct repair
      • outcomes
        • 90% return to preinjury levels of throwing
        • humeral docking associated with better patient outcomes and lower complication rate compared to figure-of-8 fixation 
        • humeral docking and cortical button techniques are biomechanically stronger than figure-of-8 and interference screw fixation
        • none of the reconstructive methods are stronger than native ligament
        • humeral docking with interference screw fixation of the ulnar side showed strength of 95% of the native MCL
Surgical Techniques
  • MCL anterior band ligament reconstruction
    • approach
      • muscle-splitting approach (decreases morbidity to flexor-pronator mass)
      • in-situ ulnar nerve decompression
        • transposition reserved for patients with preoperative symptoms, subluxating ulnar nerve and patients with ulnar nerve motor weakness
    • reconstruction
      • most techniques performed using autograft (palmaris longus, gracilis)
      • modified Jobe technique
        • figure-of-eight reconstruction (palmaris longus tendon commonly used)
        • graft passed through two tunnels in medial epicondyle of humerus and single tunnel in ulnar sublime tubercle
        • graft sutured to itself in figure-of-8 configuration
      • docking technique  
        • graft limbs are tensioned through single humeral docking tunnel
        • suture limbs passed through two bone punctures and sutured over bony bridge on medial epicondyle
      • hybrid interference-screw technique
        • interference-screw fixation into the ulna
        • docking fixation on the humerus
      • Cortical suspensory fixation, ex. "Endo-button" (Smith & Nephew) reconstruction
        • stabilize the graft with an endobutton through the ulna
    • postoperative care
      • early
        • early active wrist, elbow, and shoulder range of motion
        • strengthening exercises beginning four to six weeks post-op
      • mid-term
        • initiate a progressive throwing program at four months
        • avoid valgus stress until 4 months post-op
      • return to competitive throwing at 9-12 months post-op
Complications
  • Ulnar nerve injury
  • Medial antebrachial cutaneous (MABC) nerve injury
    • nerve is present at distal aspect of the incision
  • Fracture of ulna or medial epicondyle
  • Elbow stiffness
  • Inability to regain preinjury level throwing ability
 

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Questions (7)

(OBQ12.86) A 19-year-old male complained of right elbow pain 4 months ago after pitching in a collegiate baseball game. He underwent a period of rest and forearm strengthening and now has recurrence of pain during a throwing interval program. A MRI is shown in Figure A. What is the next most appropriate step in management? Review Topic

QID:4446
FIGURES:
1

Open ECRB tendon release and removal of the diseased tendon with repair of the tendon remnant

3%

(106/3442)

2

Arthroscopic debridement of lesion and osteotochondral autograft transplant from ipsilateral knee

2%

(73/3442)

3

Excision of the diseased tendon and reattachment of the origin of the flexor-pronator muscle group to the medial epicondyle

6%

(223/3442)

4

Open reconstruction of the ligament using ipsilateral palmaris longus tendon

83%

(2869/3442)

5

Diagnostic elbow arthroscopy, removal of posteromedial olecranon osteophytes and d├ębridement of chondromalacia

4%

(148/3442)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

Open reconstruction of the medial (ulnar) collateral ligament using ipsilateral palmaris longus tendon is indicated in medial collateral ligament injuries in high level overhand throwing athletes with symptoms recalcitrant to conservative management.

Conservative treatment of medial (ulnar) collateral ligament injuries in over-hand throwing athletes includes a period of rest from throwing followed by a flexor-pronator mass strengthening regimen. Next, the patient participates in a progressive throwing interval program.

Rettig et al. performed a Level 4 review of 31 throwing athletes with ulnar collateral ligament injuries that were treated in a nonoperatively with a minimum of 3 months rest. They found that 42% of the athletes were able to return to sport after an average of 6 months of rest, forearm strengthening, and throwing interval program.

Davidson et al. present data from a cadaveric dissection study of 11 elbows. They found that the flexor carpi ulnaris (FCU) muscle and flexor digitorum superficialis (FDS)muscle, provide medial elbow support to the medial (ulnar) collateral ligament.

Figure A is a T2 coronal MRI of the right elbow that demonstrates a ruptured medial (ulnar) collateral ligament off of the ulna.

Incorrect Answers:
Answer 1: This would be a reasonable method of management for recalcitrant ECRB tendonitis.
Answer 2: This would be a reasonable method of management for an osteochondral defect.
Answer 3: This would be a reasonable method of management for recalcitrant flexor-pronator tendonitis.
Answer 5: This would be a reasonable method of management for valgus extension overload syndrome.


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(OBQ10.212) A 22-year-old collegiate pitcher sustains a medial collateral ligament (MCL) rupture of his throwing elbow requiring surgical reconstruction. Anatomic restoration of the MCL is desired to maximize function. Which of the following best describes the kinematics of the native MCL? Review Topic

QID:3305
1

Anterior bundle becomes tight in flexion and lax in extension

18%

(444/2503)

2

The posterior bundle demonstrates the greatest change in tension from flexion to extension

56%

(1391/2503)

3

Posterior bundle becomes lax in flexion and tight in extension

7%

(174/2503)

4

Posterior bundle is isometric

4%

(101/2503)

5

The posterior bundle is isometric, but the anterior is not

15%

(380/2503)

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

The MCL (also known as the medial ulnar collateral) is an important static stabilizer of the medial elbow that can become attenuated and rupture in throwing athletes leading to pain, valgus instability, and loss of throwing velocity.

Morrey et al dissected 10 cadaver elbows to pinpoint the origin and insertion of both the medial and lateral stabilizing ligaments of the elbow. Most pertinent to this question, the anterior bundle of the MCL was found to be isometric throughout the flexion/extension arc of motion. The posterior bundle of the MCL became elongated with elbow flexion. It demonstrated the greatest change in length from extension to flexion of all the elbow ligaments.

Moritomo et al performed an in-vivo kinematic study to determine the isometric point of the lateral elbow ligaments. The radial collateral ligament was determined to be isometric through flexion and extension. The lateral ulnar collateral ligament was found to be lax in extension and tight in flexion.

In a separate study, Moritomo et al reviewed 9 patients who underwent excision of heterotopic ossification that included resection of the posterior oblique ligament of the medial collateral ligament. Range of motion was improved and no patient demonstrated instability at 4 year follow-up.

Elbow anatomy diagrams demonstrating this ligament are provided in Illustrations A and B.

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(OBQ10.216) A 25-year-old professional baseball pitcher complains of medial elbow pain during the early acceleration phase of throwing. He has lost 10 mph on his fastball. Radiographs of the elbow are provided in Figure A. EMG studies demonstrate no entrapment of the ulnar nerve. Which of the following physical exam maneuvers will most strongly confirm the correct diagnosis? Review Topic

QID:3309
FIGURES:
1

Evaluating for pain with resisted wrist flexion

4%

(80/2200)

2

Testing for Froment's sign

1%

(19/2200)

3

Evaluating for pain with Hawkins impingement test

1%

(12/2200)

4

Evaluating for pain with moving valgus stress test

90%

(1979/2200)

5

Performing the lateral pivot shift test

4%

(96/2200)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

The clinical presentation is classic for rupture of the UCL of the elbow, and the moving valgus stress test is a sensitive and specific test for diagnosis.

The moving valgus stress test is performed by applying a valgus load to the fully flexed elbow, and then quickly extending the elbow. Reproduction of pain is a positive finding for UCL rupture.

O'Driscoll et al evaluated 21 patients with MRI's suggestive of partial UCL tear. All patients underwent the moving valgus stress test prior to diagnostic surgery. Seventeen of the 21 patients demonstrated rupture of the UCL intra-operatively. The moving valgus stress test demonstrated a sensitivity of 100% (17/17) and specificity of 75%(3/4).

Azar et al reviewed 91 throwers who underwent surgical treatment of elbow UCL ruptures. Subcutaneous nerve transposition was performed in all patients although only 9 had concomitant symptoms of ulnar nerve entrapment. Eighty percent returned to their prior level of throwing by one year following surgery.

Figure A shows a normal xray. Illustration A demonstrates an example of the moving valgus stress test. Illustration V is a video showing a moving valgus stress test.

Incorrect Answers:
Answer 1: Pain with resisted wrist flexion suggests medial epicondylitis.
Answer 2: Froment's sign is present with ulnar neuropathy.
Answer 3: Hawkin's test evaluates the shoulder for impingement.
Anawer 5: The lateral pivot shift test evaluates for posterolateral rotatory instability.

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Question COMMENTS (3)

(OBQ09.105) All of the following protect the elbow from valgus loads during the throwing cycle EXCEPT? Review Topic

QID:2918
1

Flexor-pronator muscle contraction

6%

(17/282)

2

Reduced fastball velocity

7%

(21/282)

3

Increased glenohumeral internal rotation torque

54%

(152/282)

4

Forearm pronation

12%

(35/282)

5

Scapular protraction/retraction

20%

(55/282)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

During a thrower's kinetic chain, increased shoulder internal rotation torque contributes to increased valgus elbow loads. Marshall et al described the importance of proximal to distal control of the upper extremity in producing angular and racket velocity and theorized that longitudinal rotations should be considered during injury prevention programs. Davis et al demonstrated that correct pitching mechanics offered the most efficient throwing velocity for a given shoulder internal rotation torque and elbow valgus load. Thus scapular dynamic control, correct pitching mechanics, pronation of the forearm with dynamic flexor-pronator muscle contraction protects the elbow from valgus loads.


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(OBQ08.242) Which of the following is the primary stabilizer to resist valgus stress in mid-flexion of the elbow? Review Topic

QID:628
1

Ulno-humeral articulation

3%

(17/511)

2

Radio-capitellar articulation

4%

(22/511)

3

Anterior oblique ligament of the medial ulnar collateral ligament

74%

(378/511)

4

Posterior oblique ligament of the medial ulnar collateral ligament

18%

(90/511)

5

Flexor-pronator muscle mass

1%

(3/511)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

The anterior oblique ligament (formerly known as the anterior bundle) provides the major contribution to valgus stability. The terminology has changed over the past decade as the anatomy is now better understood.

Hariri and Safran have a recent review which describes the anatomy and present terminology well. The UCL is a complex consisting of the anterior oblique ligament (AOL), the posterior oblique ligament (POL), and the transverse ligament. (see Illustration A) The anterior oblique ligament is composed of an anterior band and posterior band that tighten in a reciprocal fashion as the elbow is flexed and extended. In the presence of valgus overload, the anterior band is most vulnerable in elbow extension, whereas the posterior band is more vulnerable in elbow flexion. The olecranon is an important stabilizer of the elbow in extension; at 25 degrees flexion the olecranon is unlocked from its fossa and the ulnar collateral ligament becomes the most important stabilizer. The radial head is an important secondary stabilizer in extension as well as flexion. The transverse band plays no role in joint stability because it originates and inserts on the same bone.

A large source of confusion is the fact that what is now known as the "AOL" is also formerly referred to as the anterior bundle (or even just anterior band which you will encounter on older questions/texts), see Illustration B.

ILLUSTRATIONS:

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Question COMMENTS (5)

(OBQ08.247) The greatest stress on the medial ulnar collateral ligament of the elbow occurs during which phase of throwing? Review Topic

QID:633
1

Wind-up

1%

(5/435)

2

Early cocking

9%

(38/435)

3

Late cocking

81%

(351/435)

4

Ball release

8%

(33/435)

5

Follow through

2%

(7/435)

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PREFERRED RESPONSE 3

The late cocking and early acceleration phase of the overhead throw causes the greatest amount of valgus stress to the elbow. During this phase, the forearm lags behind the upper arm and generates valgus stress while the elbow is primarily dependent on the anterior band of the UCL for stability. The windup phase is benign for the elbow. In early cocking, the rotator cuff and deltoid are active, not the elbow. Ball release is the culmination of cocking and acceleration, but the maximal joint forces have already occurred across the UCL due to the rapid combination of valgus and extension during late cocking and early acceleration. In deceleration, the elbow flexors are most active to prevent hyperextension.


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Question COMMENTS (0)

(OBQ07.119) During which phase of the overhead throwing cycle is a baseball pitcher most likely to rupture the medial ulnar collateral ligament complex of the elbow? Review Topic

QID:780
1

Follow-through

5%

(16/343)

2

Ball release

5%

(16/343)

3

Early acceleration

76%

(261/343)

4

Early cocking

13%

(44/343)

5

Wind-up

2%

(6/343)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

The medial UCL is subjected to near-failure tensile stresses during the late cocking/early acceleration phase of throwing.

The medial ulnar collateral ligament, or medial collateral ligament of the elbow, is composed of three bundles: an anterior bundle, a posterior bundle, and a variable transverse oblique bundle. The anterior bundle of the ulnar collateral ligament is the primary restraint to valgus force of the elbow from 30 to 120 degrees of flexion. Biomechanical testing has shown that valgus forces as high as 64 N.m at the elbow during late cocking and early acceleration phases of throwing with compressive forces of 500 N at the lateral radiocapitellar articulation as the elbow moves from 110 to 20 degrees of flexion and velocities as high as 3000 deg/sec.

The Cain et al. paper is a current concepts review of elbow injuries in throwers from the group with the world's largest experience in treating these injuries.


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