Sports Medicine: The Elbow
Christine B. Chung, M.D. Professor of Radiology Musculoskeletal Division UCSD and VA Healthcare System
Elbow vis-à-vis Sports Injury • Anatomy • Basic Mechanism of Injury • Manifestation of Injury in Adult Versus Pediatric Population • Ligament Injury and Chronic Repetitive Microtrauma in the Athlete
Osseous and Articular Anatomy
Pseudodefect of the Capitulum • Result of a groove between the capitulum and the lateral epicondyle of humerus
Pseudodefect of the Capitulum
Osseous and Articular Anatomy
Humeroradial
Humeroulnar
Prox Radioulnar
Normal Distribution of Contrast
Ligament Anatomy
Ulnar Collateral Ligament Complex Anterior bundle Posterior bundle Transverse bundle
Lateral Collateral Ligament Complex Radial Collateral Lateral Ulnar Collateral Annular Accessory Posterior Annular
Ulnar Collateral Ligament Complex
Ulnar Collateral Ligament Anterior Bundle
Distal UCL Attachment • Flush against the sublime tubercle • Within 1 mm of the sublime tubercle • Within 3 mm of the sublime tubercle
Ulnar Collateral Ligament Anterior Bundle
Ulnar Collateral Ligament Posterior Bundle
Anconeus
Anconeus Epitrochlearis
• Accessory muscle above level of joint on posteromedial aspect of humerus
Pediatric Cubital Tunnel Syndrome Anconeus Epitrochlearis
Boero, et al., J Shoulder Elbow Surg 18: e21-e23, 2009
Lateral Ulnar Annular Radial Collateral Collateral Accessory Annular
Around radial head Lateral epicondyle Lateral epicondyle to ulna to to ulna annular ligament Annular ligament to ulna
Radial Collateral Ligament Complex
Radial Collateral Ligament Complex
Ulnar Collateral Band Radial Collateral Complex
Ulnar Collateral Band Radial Collateral Complex
Annular Ligament
Annular Ligament Injury
Annular Ligament Injury
Annular Ligament Rupture 13 Year Old Overhead Thrower Normal Annular Ligament
Lateral Synovial Fringe • Synovial fold • Mimics IAB • Often clinically silent • Aggravated by pronation and extension
Synovial Folds and Plica
Elbow Plica Syndrome: Pediatric Patient
Meyers, et al., Pediatr Radiol May 2012, E Pub Ahead of Print
Elbow Plica Syndrome: Pediatric Patient Posterolateral Plica
Meyers, et al., Pediatr Radiol May 2012, E Pub Ahead of Print
Elbow Stability
Ulnohumeral Articulation
• Likened to a fortress
Radiohumeral Articulation
CFT AMCL
CET LUCL
y Outer wall = Primary stabilizers y Inner wall = Secondary stabilizers
Elbow Stability • Lateral instability • Medial instability • Dislocation y Simple • Soft tissue injury alone (PLRI Classification)
y Complex • Soft tissue injury in conjunction with fracture
Mechanism of Failure Material Property of Tissue
13 year old pitcher
14 year old pitcher 15 year old pitcher
Lateral Instability
Medial Instability
Valgus Instability
UCL Injury T-Sign • Initially described in small series of overhead throwers with both MRI and CT arthrography • Leakage of contrast around humerus and more commonly ulna with no gross extracapsular extravasation Mirowitz and London, Radiology, 185: 573576, 1992
Timmerman and Andrews, Am J Sports Med, 22: 33-36, 1994
UCL Injury T-Sign Ligament and Periosteal Stripping 14 year old
Ulnar Collateral Ligament STIR
Post-MRA
• MR arthrography sensitive (86%), specific (100%) and accurate (86%) for detection of undersurface UCL tears Schwartz, et al., Radiology 197: 297-299, 1995
Ulnar Collateral Ligament Tear 16 year old pitcher • Typically seen in late adolescent and teen-aged pitchers after medial epicondyle has fused • Full-thickness mid substance tears most common y Full-thickness and partialthickness tears of humeral and ulnar attachments may occur
• Radiographs typically normal • MRI shows redundancy, irregularity, and thickening of ligament with surrounding edema
Image Courtesy of Rick Kijowski
Valgus Extension Overload • Acceleration phase y y y y
Triceps contracts Elbow extends Object thrown Force of extension absorbed by capsule/ biceps/ brachialis
Valgus Extension Overload • With existing valgus instability, elbow slightly subluxed in valgus position as flexion occurs
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Valgus Extension Overload
Repetitive Tensile Force – Adult Hypertrophy Sublime Tubercle
Valgus Extension Overload Repetitive Tensile Force – Pediatric Little Leaguer Elbow – 13 year old
• Chronic repetitive valgus stress from recurrent contraction of flexorpronator muscle group y In children, main stabilizer to valgus stress is flexor-pronator muscle group y Failure at the weakest link - unfused apophyseal plate
• Medial epicondylar physeal widening and edema may progress to avulsion of apophysis into the joint
Valgus Extension Overload Repetitive Tensile Force UCL – Pediatric 10 year old pitcher with pain
Valgus Extension Overload Repetitive Tensile Force – Pediatric 14 year old pitcher with pain
Valgus Extension Overload Repetitive Tensile Force UCL – Pediatric 15 year old pitcher pain 6 months
Valgus Extension Overload Repetitive Tensile Force UCL – Pediatric 16 year old pitcher, Felt pop
Valgus Extension Overload • Results in impaction radiocapitellar joint with subsequent osteochondral lesion
Valgus Extension Overload Lateral Compression – Adult Osteochondral Lesion
Valgus Extension Overload Lateral Compression – Pediatric Osteochondritis Dissecans
Valgus Extension Overload Posterior and Posteromedial Bone Lesion – Adult
• Posteromedial Osteophyte
• Olecranon Stress Fracture
Valgus Extension Overload Posterior Extension Overload – Pediatric
Throwing Arm
Non-Throwing Arm
• Olecranon stress change with sclerosis, irregularity and widening of the physis Images Courtesy of Rick Kijowski
Valgus Extension Overload
• Ulnar Nerve Injury
• Common Flexor Tendon Injury
Elbow vis-à-vis Sports Injury • Anatomy • Basic Mechanism of Injury • Manifestation of Injury in Adult Versus Pediatric Population • Ligament Injury and Chronic Repetitive Microtrauma in the Athlete
