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Introduction
  • Attenuation or rupture of the ulnar collateral ligament of the elbow leads to valgus instability
  • Epidemiology
    • demographics
      • 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 present with a "pop" associated with pain and difficulty throwing
  • 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
      • paresthesias down ulnar arm into ring and small fingers
  • Physical examination
    • inspection
      • tenderness along elbow 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
        • flex elbow to 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
        • may show loose bodies
    • optional views
      • oblique views to evaluate the olecranon
      • gravity or manual stress radiographs  
        • may show medial joint-line opening >3 mm (diagnostic)
    • findings
      • assess for a posteromedial osteophyte (due to valgus extension overload)
  • MRI
    • views
      • UCL pathology 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
Differential
 
 
Varus Posteromedial Rotatory Instability (VPMRI)
Valgus Posterolateral Rotatory Instabiliy (VPLRI) 
Radial head
No radial head fracture
Radial head fracture
Coronoid fracture
>15% (anteromedial facet)
<15% (tip fracture)
MCL
Posterior band of MCL ruptured, anterior band intact
Anterior band of MCL ruptured
LCL
LCL complex (includes LUCL) avulsion
LCL complex (includes LUCL) avulsion
Physical exam
Valgus stress, moving valgus, milking maneuver Varus stress, chair rise, lateral pivot shift 
 
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 ulnar nerve symptoms, subluxating ulnar nerve and patients with ulnar nerve motor weakness
    • reconstruction
      • most techniques performed using autograft (palmaris longus, gracilis); allograft is also used
      • 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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