Little League Elbow Syndrome

Background

Little league elbow (LLE) syndrome is a valgus overload or overstress injury to the medial elbow that occurs as a result of repetitive throwing motions. Over the past several decades, the number of organized sports for children has grown significantly, with millions of children participating in organized athletics each year. This increase in participation has been paralleled by an increase in sports-related injuries in the pediatric population.[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]

Increased single-sport participation with year-round training, higher intensities at young ages, and longer competitive seasons are contributing factors to the increased injury rates seen in pediatric athletes. Conditioning and training errors also contribute significantly to the risk and frequency of injury. Although briefly discussed below, injuries to the lateral, posterior, and anterior elbow are separate entities and should not be confused with the medial injuries referred to as little league elbow syndrome.

During the throwing motion, valgus stress is placed on the elbow. This valgus stress results in tension on the medial structures (ie, medial epicondyle, medial epicondylar apophysis, medial collateral ligament complex) and compression of the lateral structures (ie, radial head, capitellum). Repeated stress results in overuse injury when tissue breakdown exceeds tissue repair. Recurrent microtrauma of the elbow joint can lead to little league elbow, a syndrome that encompasses (1) delayed or accelerated growth of the medial epicondyle (medial epicondylar apophysitis), (2) traction apophysitis (medial epicondylar fragmentation), and (3) medial epicondylitis.[1, 8, 12, 13, 14, 15]

Medial epicondylar apophysitis and stress fractures through the medial epicondylar epiphyses caused by repetitive valgus stress generally manifest with progressive medial pain, decreased throwing effectiveness, and decreased throwing distance.

Other causes of medial elbow pain include avulsion fractures of the medial epicondyle and ulnar collateral ligament (UCL) sprains or tears. Although a fracture is usually an acute traumatic event, a preceding history of medial elbow pain is common and is thought to be a risk factor for progression to acute fracture. Therefore, any thrower who is experiencing medial elbow pain should refrain from pitching until he or she has had a thorough evaluation.[1, 3, 5, 8, 16]

A medial epicondyle fracture manifests as point tenderness and swelling over the medial epicondyle, often with an elbow flexion contracture greater than 15°. Repetitive medial stress can also cause attenuation and microstretching of the UCL complex, causing mild instability over time.[1]

UCL injuries can manifest as acute ligament tears following a single valgus stress or as overuse sprains following repetitive valgus overloads. The clinical presentation is similar to little league elbow; however, the typical age range of the athlete is the older teenager who is skeletally mature. Suspected UCL injuries should be referred for further evaluation by a sports medicine specialist. Athletes with UCL injuries should not be allowed to pitch until they have been evaluated.

Although uncommon in children, neurologic injuries such as C8-T1 radiculopathy and ulnar neuritis can manifest as medial elbow pain and should be included in the differential diagnosis (see Differentials and Other Problems to Be Considered).

Lateral compression of the elbow most frequently results in injuries to the capitellum and radial head. Osteochondrosis of the capitellum (known as Panner disease) generally occurs in children aged 7-12 years and manifests as dull, achy, activity-related lateral elbow pain. Swelling, clicking, and decreased range of motion are uncommon associated symptoms. Panner disease tends to be a benign self-limited condition that does well over time and is treated with complete rest from inciting activities such as throwing and weight bearing on the elbow. Osteochondral injuries can also be observed in the radial head.

Osteochondritis dissecans (OCD) of the capitellum occurs in adolescents aged 13-17 years. This is a localized injury to subchondral bone that results from repetitive lateral compression of the elbow during overhead motions. These patients report a general dull elbow pain that worsens with activity, often have a flexion contracture of 15° or greater, and may have mechanical symptoms of clicking or popping. Loose body formation, residual capitellum deformity, and elbow degenerative joint disease are potential sequelae. Different treatment options are used based on the age and skeletal maturity of the patient and the type of lesion present.

Osteochondritis dissecans lesions can be separated into type I, which has no displacement and no articular cartilage fracture; type II, which has evidence of articular cartilage fracture or partial displacement; and type III, which is completely displaced with loose bodies in the joint.

Posterior elbow injuries also occur as a result of throwing. During the follow-through stage of throwing, extension overload and valgus stress can result in injury of the olecranon. These athletes present with posterior elbow pain, clicking, and possible loss of elbow extension. Loose bodies and olecranon nonunion can occur in younger athletes. Older athletes may experience olecranon fractures or secondary osteophyte formation. These injuries are sometimes treated surgically.[1, 3, 4, 5, 6, 7, 9, 10, 11, 17]

For excellent patient education resources, visit eMedicineHealth's First Aid and Injuries Center. Also, see eMedicineHealth's patient education article Repetitive Motion Injuries.

NextEpidemiologyFrequencyUnited States

Annually, an estimated 4.8 million children aged 5-14 years participate in baseball and softball. The incidence of all baseball-related overuse injuries is 2-8% per year. The incidence of overuse injuries in the 9- to 12-year-old range for baseball is 20-40%, and in the adolescent age group is 30-50%. The true incidence of sports-related injuries is unknown because a large number of athletes never seek medical care. Early recognition of little league elbow syndrome is important, because it leads to better outcomes and decreases the risk of persistent functional disabilities in the athletes.

International

No data are available for the annual incidence of little league elbow syndrome in the international community.

PreviousNextFunctional Anatomy

Evaluation of the young adolescent elbow presents some anatomic challenges to the healthcare provider in that the elbow consists of numerous ossification centers and cartilaginous physes. Becoming familiar with the chronologic order of appearance and ossification of these growth centers is important. Consider the mnemonic CRITOE (ie, capitellum, radius, internal epicondyle, trochlea, olecranon, external epicondyle).

Each of the ossification centers appears at a relatively predictable time starting around age 1-2 years, with 2-year intervals between the next center's appearance. Closure of each of the apophyses occurs from age 14 to 16 years, with the medial epicondyle specifically closing at approximately age 15 years. The elbow likely reaches full skeletal maturity by the late teen years, at which time injuries to the UCL are far more common. Until then, the young thrower is at risk for little league elbow syndrome.[1, 4, 12, 16, 18]

The static stabilizers around the elbow include the bony articulations, the joint capsule, and the various ligament bundles. The medial (ulnar) collateral ligamentous complex consists of the anterior oblique bundle, posterior oblique bundle, and transverse ligament. These structures are the primary medial support of the elbow during valgus stress. The lateral (radial) ligamentous complex, composed of the lateral collateral, lateral ulnar collateral, and accessory lateral collateral ligaments, provides support during varus stress.

The dynamic stabilizers primarily include the muscles that cross the elbow joint, such as the triceps, biceps, and brachioradialis. The flexor-pronator group stabilizes against valgus stress, and the extensor-supinator group stabilizes against varus stress.

Elbow biomechanics include flexion/extension range of motion and pronation/supination. Slight hyperextension 5-15° through flexion of approximately 150° is within normal limits. Baseball pitchers with years of throwing experience often have relative 5-10° flexion contractures on their dominant side; however, in the young thrower, a flexion contracture can be a sign of injury. Pronation of 75° and supination of 85° is normal. Varus-valgus laxity of 3-4° is normal.

PreviousNextSport-Specific Biomechanics

One should be familiar with the stages of throwing to understand the complexities of the biomechanical forces that contribute to the young thrower's risk of injury, such as in little league elbow syndrome. The pitching or throwing motion can be divided into 6 stages. Medial elbow injuries are the most common type seen in throwers and occur most commonly in the cocking and acceleration phases of throwing, owing to the presence of maximum valgus extension or distraction forces.[1, 12, 13, 14, 15]

Windup begins with the pitcher balancing his weight over his rear leg, with the elbow flexed and the forward leg flexed at least 90°. Stride starts with the lead leg beginning to descend toward the plate, and the 2 arms separate. The elbow moves from extension into flexion of 80-100°. Cocking occurs when the humerus is in extreme abduction and external rotation and the elbow is flexed. The lead foots contacts the ground, the pelvis and trunk rotate, and elbow torque transfers valgus force across the elbow joint. During this phase, medial tension and lateral compression forces are applied to the elbow. Acceleration is the shortest pitching phase, lasting from maximal external shoulder rotation to ball release. In this phase, the trunk rotates as the elbow extends. Maximum elbow angular velocity is comparable during fastballs, sliders, and curveballs, but it less during the change-up pitch. Velocity comes from rotation of the trunk, shoulder, and hips. Varus torque forces during this phase act to resist the valgus extension "overload" phenomenon and can contribute to posterior elbow (olecranon) impingement. Deceleration is initiated at ball release and ends when the shoulder has reached full internal rotation. The body must decelerate the arm and dissipate forces in the elbow and shoulder. Follow-through is the final phase of the baseball pitch and ends with the pitcher reaching a balanced fielding position with full-trunk rotation and the body weight fully transferred from the rear leg to the forward leg. During follow-through, the elbow flexes into a relaxed position and crosses the body. PreviousProceed to Clinical Presentation , Little League Elbow Syndrome

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Medial Condylar Fracture of the Elbow

Background

Medial condylar fractures of the elbow, demonstrated in the images below, are rare in adults and children; prompt recognition of these sometimes elusive injuries is imperative so that complications can be averted.

Milch classification of condylar fractures. NextEpidemiologyFrequencyUnited States

Trauma to the elbow has a high potential for complications and residual functional disability. Luckily, fractures of the humeral condyles are uncommon in adults. Medial condylar fractures are less common than fractures of the lateral condyle. Together, these injuries account for approximately 5% of all distal humerus fractures in adults.

During adolescence, the distal humerus is the second most common site of physeal injury (second only to the distal radius). Supracondylar fractures account for approximately two thirds of distal humeral injuries in children. In children with elbow fractures, isolated medial condyle fractures are uncommon and account for approximately 1-2% of all distal humerus fractures. In children, medial condyle fractures occur at a peak age of 8-12 years.

Fracture of the medial epicondyle of the elbow, as seen in the image below, is common and occurs in approximately 10% of pediatric elbow fractures. Most of these injuries occur in males aged 10-14 years.

Medial epicondylar fracture PreviousNextFunctional Anatomy

The elbow joint is composed of the bony articulation between the humerus, ulna, and radius. The distal end of the humerus can be divided into the medial and lateral condyles. The articular portion of the medial condyle is the trochlea, and the articular portion of the lateral condyle is the capitulum. The epicondyle is considered part of the nonarticular portion of the condyle. The dividing point for the distal humerus, separating the medial and lateral condyles, is the capitulotrochlear sulcus.

Distinguishing between the articular and nonarticular surface of the condyles is important in the diagnosis and management of condylar fractures. By definition, fractures that involve only the intra-articular surface have no muscular attachments and can only be repositioned by pressure of the opposing articular surface or by open reduction and internal fixation. Fractures that extend beyond the joint capsule have attached muscle and ligaments. The position of the fracture fragment is often influenced by its muscular attachment.

The stability of the elbow is enhanced by its surrounding ligamentous structures. The medial collateral ligament and the lateral collateral ligament (ie, ulnar collateral ligament, radial collateral ligament) provide further stability of the elbow. The radiocapitellar joint is supported by the radial collateral and annular ligaments.

Collectively, the forearm musculature originates from the bony epicondyle prominences. The wrist flexors originate from the medial epicondyle, and the wrist extensors originate from the lateral epicondyle. Because the forearm musculature traverses the elbow joint, some inherent stability to the joint is conferred by muscular contraction.

The structures of the upper arm and elbow are located in either the anterior or posterior compartments. The anterior compartment contains the biceps brachii, brachialis, and coracobrachialis muscles. The anterior compartment also contains the brachial artery, median nerve, musculocutaneous nerve, and ulnar nerve. The ulnar nerve passes behind the medial condyle as it enters the forearm. Because of its location and relatively tight tethering to the epicondyle, the ulnar nerve can be injured when the medial humeral condyle is fractured. The posterior compartment contains the triceps brachii muscle and the radial nerve.

The bony anatomy of the elbow in the pediatric population deserves special mention. Many of the challenges encountered in diagnosing elbow fractures in pediatric patients involve proper knowledge of the ossification centers of the elbow. In general, ossification of the growth centers begins at an earlier age in girls than in boys. Although variation exists, ossification of the growth centers of the elbow occurs at the following times:

Capitellum - 11 monthsMedial epicondyle - 4-6 yearsRadial head - 5-6 yearsOlecranon - 6-8 yearsTrochlea - 9-10 yearsLateral epicondyle - 10-12 yearsPreviousNextSport Specific Biomechanics

By definition, the elbow is a true hinge joint that is very stable to all motions except varus and valgus stress. The articulation of the trochlea of the humerus and the olecranon of the ulna defines the plane of flexion and extension at the elbow. The elbow also allows for pronation and supination at the radiocapitellar articulation. The radiocapitellar joint does provide some stability against valgus stress by acting as a buttress to prevent medial elbow opening. Stability is further enhanced by the strength of the ulnar collateral ligament, the principal stabilizing ligament of the elbow that resists valgus stress.

The radial-collateral ligament protects the joint from posterolateral rotary instability and is usually injured during elbow dislocation. The wrist extensor tendons that originate on the lateral intermuscular septum of the arm and the lateral epicondyle provide the elbow with stabilization against varus stress.

PreviousProceed to Clinical Presentation , Medial Condylar Fracture of the Elbow

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Elbow Dislocation

Background

Elbow dislocation is the most common dislocation in children; in adults, it is the second most common dislocation after that of the shoulder.[1, 2, 3, 4, 5] The elbow is amazingly stable, relying more on bony anatomy configuration for stability rather than ligaments. Considerable force is necessary to dislocate the elbow; sports activities account for up to 50% of elbow dislocations, and this type of injury is more commonly seen in adolescent and young adult populations (see the image below).

Posterior and lateral dislocation of the left elbow in a soccer goalie. A small avulsion fracture of the olecranon is present.

Posterior elbow dislocations comprise over 90% of elbow injuries. Early recognition of this injury is required due to the need for early reduction, given a higher likelihood for poor function and possible neurovascular compromise with delays in reduction.[1, 2, 3, 4, 6, 7] Associated fractures are not infrequent with elbow dislocations, given the force that is required to dislocate the elbow.

Anterior dislocations are seen much less commonly than posterior dislocations. Divergent dislocations, which result in the ulna and radius dislocating in opposite directions, are even more rare. In the pediatric population, radial head subluxation is the main cause of elbow dislocations.

For excellent patient education resources, visit eMedicineHealth's First Aid and Injuries Center. Also, see eMedicineHealth's patient education articles Elbow Dislocation and Broken Elbow.

NextEpidemiologyFrequencyUnited States

The rate of elbow dislocation is 6-13 cases per 100,000 people, and this injury occurs more frequently in males than in females. Of all elbow dislocations, 10-50% are sports related. More than 90% of elbow dislocations are posterior dislocations.

PreviousNextFunctional Anatomy

The elbow is primarily a flexion-extension hinge joint, which also allows for pronation and supination. Normal range of motion (ROM) at the elbow should be extension to 0° and flexion to 150°.[1, 2]

The humerus and ulna form a very stable unit, which is generally resistant to disruption unless considerable force is applied. This inherent stability also reduces the likelihood of redislocation. The primary bony stabilizers are the coronoid and radial head.

The medial collateral ligament (MCL) and lateral collateral ligament (LCL) comprise the ligamentous stability of the elbow and act as a back-up system to the elbow's natural bony stability. The MCL consists of 3 bands, the anterior oblique, posterior oblique, and the transverse. The anterior band provides most of the resistance to valgus stress. The LCL has 2 bands, the ulnar collateral and radial collateral.

The 2 main compartments of the elbow are the anterior and posterior compartments. The anterior compartment contains the brachial artery and the ulnar and median nerves. This compartment is more commonly affected by dislocations and is the reason for clinical concern regarding brachial artery disruption and median or ulnar nerve entrapment.[1, 2, 4, 8]

The ulnar nerve passes posteriorly to the medial epicondyle of the humerus, and then it travels deep in the forearm before becoming more superficial again at the wrist. The close proximity of the ulnar nerve to the medial epicondyle allows for the increased likelihood of entrapment when a dislocation occurs. The median nerve is also frequently affected and travels intimately with the brachial artery, which predisposes to simultaneous injury for both the artery and nerve. The posterior compartment contains the radial nerve and triceps brachii muscle.

Anatomically, the mechanism for elbow dislocations is believed to occur as a continuum of damaged/torn structures, beginning laterally with the ulnar portion of the LCL, followed by complete LCL disruption, then damage to the anterior and posterior compartments. The posterior MCL can then become damaged, leaving the anterior portion intact. Further force can allow the elbow to pivot about the anterior bundle of the MCL, potentially damaging it. The LCL, therefore, is considered to be the initial weak link in elbow dislocations.

In the pediatric population, the clinician should be aware of the 6 ossification centers of the elbow joint as well as the annular ligament. The capitellum, radial head, internal (medial) epicondyle, trochlea, olecranon, and external (lateral) epicondyle (CRITOE) is the order in which the ossification centers appear. These centers may often be mistaken for fractures on x-rays. NOTE: A general rule of thumb for the time of appearance of the ossification centers is "1-3-5-7-9-11," which are the ages in years, corresponding to the CRITOE pneumonic.

In cases in which there is radial head subluxation, the radial head slips under the annular ligament and becomes trapped.

PreviousNextSport-Specific Biomechanics

Biomechanically, no single sport definitively increases the risk of elbow dislocations; however, sports that increase the likelihood of a person falling onto an outstretched hand (ie, FOOSH injury) (eg, gymnastics, rollerblading, cycling) may theoretically increase the risk of elbow dislocation.

PreviousProceed to Clinical Presentation , Elbow Dislocation

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Little League Elbow Syndrome

Background

Little league elbow (LLE) syndrome is a valgus overload or overstress injury to the medial elbow that occurs as a result of repetitive throwing motions. Over the past several decades, the number of organized sports for children has grown significantly, with millions of children participating in organized athletics each year. This increase in participation has been paralleled by an increase in sports-related injuries in the pediatric population.[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]

Increased single-sport participation with year-round training, higher intensities at young ages, and longer competitive seasons are contributing factors to the increased injury rates seen in pediatric athletes. Conditioning and training errors also contribute significantly to the risk and frequency of injury. Although briefly discussed below, injuries to the lateral, posterior, and anterior elbow are separate entities and should not be confused with the medial injuries referred to as little league elbow syndrome.

During the throwing motion, valgus stress is placed on the elbow. This valgus stress results in tension on the medial structures (ie, medial epicondyle, medial epicondylar apophysis, medial collateral ligament complex) and compression of the lateral structures (ie, radial head, capitellum). Repeated stress results in overuse injury when tissue breakdown exceeds tissue repair. Recurrent microtrauma of the elbow joint can lead to little league elbow, a syndrome that encompasses (1) delayed or accelerated growth of the medial epicondyle (medial epicondylar apophysitis), (2) traction apophysitis (medial epicondylar fragmentation), and (3) medial epicondylitis.[1, 8, 12, 13, 14, 15]

Medial epicondylar apophysitis and stress fractures through the medial epicondylar epiphyses caused by repetitive valgus stress generally manifest with progressive medial pain, decreased throwing effectiveness, and decreased throwing distance.

Other causes of medial elbow pain include avulsion fractures of the medial epicondyle and ulnar collateral ligament (UCL) sprains or tears. Although a fracture is usually an acute traumatic event, a preceding history of medial elbow pain is common and is thought to be a risk factor for progression to acute fracture. Therefore, any thrower who is experiencing medial elbow pain should refrain from pitching until he or she has had a thorough evaluation.[1, 3, 5, 8, 16]

A medial epicondyle fracture manifests as point tenderness and swelling over the medial epicondyle, often with an elbow flexion contracture greater than 15°. Repetitive medial stress can also cause attenuation and microstretching of the UCL complex, causing mild instability over time.[1]

UCL injuries can manifest as acute ligament tears following a single valgus stress or as overuse sprains following repetitive valgus overloads. The clinical presentation is similar to little league elbow; however, the typical age range of the athlete is the older teenager who is skeletally mature. Suspected UCL injuries should be referred for further evaluation by a sports medicine specialist. Athletes with UCL injuries should not be allowed to pitch until they have been evaluated.

Although uncommon in children, neurologic injuries such as C8-T1 radiculopathy and ulnar neuritis can manifest as medial elbow pain and should be included in the differential diagnosis (see Differentials and Other Problems to Be Considered).

Lateral compression of the elbow most frequently results in injuries to the capitellum and radial head. Osteochondrosis of the capitellum (known as Panner disease) generally occurs in children aged 7-12 years and manifests as dull, achy, activity-related lateral elbow pain. Swelling, clicking, and decreased range of motion are uncommon associated symptoms. Panner disease tends to be a benign self-limited condition that does well over time and is treated with complete rest from inciting activities such as throwing and weight bearing on the elbow. Osteochondral injuries can also be observed in the radial head.

Osteochondritis dissecans (OCD) of the capitellum occurs in adolescents aged 13-17 years. This is a localized injury to subchondral bone that results from repetitive lateral compression of the elbow during overhead motions. These patients report a general dull elbow pain that worsens with activity, often have a flexion contracture of 15° or greater, and may have mechanical symptoms of clicking or popping. Loose body formation, residual capitellum deformity, and elbow degenerative joint disease are potential sequelae. Different treatment options are used based on the age and skeletal maturity of the patient and the type of lesion present.

Osteochondritis dissecans lesions can be separated into type I, which has no displacement and no articular cartilage fracture; type II, which has evidence of articular cartilage fracture or partial displacement; and type III, which is completely displaced with loose bodies in the joint.

Posterior elbow injuries also occur as a result of throwing. During the follow-through stage of throwing, extension overload and valgus stress can result in injury of the olecranon. These athletes present with posterior elbow pain, clicking, and possible loss of elbow extension. Loose bodies and olecranon nonunion can occur in younger athletes. Older athletes may experience olecranon fractures or secondary osteophyte formation. These injuries are sometimes treated surgically.[1, 3, 4, 5, 6, 7, 9, 10, 11, 17]

For excellent patient education resources, visit eMedicineHealth's First Aid and Injuries Center. Also, see eMedicineHealth's patient education article Repetitive Motion Injuries.

NextEpidemiologyFrequencyUnited States

Annually, an estimated 4.8 million children aged 5-14 years participate in baseball and softball. The incidence of all baseball-related overuse injuries is 2-8% per year. The incidence of overuse injuries in the 9- to 12-year-old range for baseball is 20-40%, and in the adolescent age group is 30-50%. The true incidence of sports-related injuries is unknown because a large number of athletes never seek medical care. Early recognition of little league elbow syndrome is important, because it leads to better outcomes and decreases the risk of persistent functional disabilities in the athletes.

International

No data are available for the annual incidence of little league elbow syndrome in the international community.

PreviousNextFunctional Anatomy

Evaluation of the young adolescent elbow presents some anatomic challenges to the healthcare provider in that the elbow consists of numerous ossification centers and cartilaginous physes. Becoming familiar with the chronologic order of appearance and ossification of these growth centers is important. Consider the mnemonic CRITOE (ie, capitellum, radius, internal epicondyle, trochlea, olecranon, external epicondyle).

Each of the ossification centers appears at a relatively predictable time starting around age 1-2 years, with 2-year intervals between the next center's appearance. Closure of each of the apophyses occurs from age 14 to 16 years, with the medial epicondyle specifically closing at approximately age 15 years. The elbow likely reaches full skeletal maturity by the late teen years, at which time injuries to the UCL are far more common. Until then, the young thrower is at risk for little league elbow syndrome.[1, 4, 12, 16, 18]

The static stabilizers around the elbow include the bony articulations, the joint capsule, and the various ligament bundles. The medial (ulnar) collateral ligamentous complex consists of the anterior oblique bundle, posterior oblique bundle, and transverse ligament. These structures are the primary medial support of the elbow during valgus stress. The lateral (radial) ligamentous complex, composed of the lateral collateral, lateral ulnar collateral, and accessory lateral collateral ligaments, provides support during varus stress.

The dynamic stabilizers primarily include the muscles that cross the elbow joint, such as the triceps, biceps, and brachioradialis. The flexor-pronator group stabilizes against valgus stress, and the extensor-supinator group stabilizes against varus stress.

Elbow biomechanics include flexion/extension range of motion and pronation/supination. Slight hyperextension 5-15° through flexion of approximately 150° is within normal limits. Baseball pitchers with years of throwing experience often have relative 5-10° flexion contractures on their dominant side; however, in the young thrower, a flexion contracture can be a sign of injury. Pronation of 75° and supination of 85° is normal. Varus-valgus laxity of 3-4° is normal.

PreviousNextSport-Specific Biomechanics

One should be familiar with the stages of throwing to understand the complexities of the biomechanical forces that contribute to the young thrower's risk of injury, such as in little league elbow syndrome. The pitching or throwing motion can be divided into 6 stages. Medial elbow injuries are the most common type seen in throwers and occur most commonly in the cocking and acceleration phases of throwing, owing to the presence of maximum valgus extension or distraction forces.[1, 12, 13, 14, 15]

Windup begins with the pitcher balancing his weight over his rear leg, with the elbow flexed and the forward leg flexed at least 90°. Stride starts with the lead leg beginning to descend toward the plate, and the 2 arms separate. The elbow moves from extension into flexion of 80-100°. Cocking occurs when the humerus is in extreme abduction and external rotation and the elbow is flexed. The lead foots contacts the ground, the pelvis and trunk rotate, and elbow torque transfers valgus force across the elbow joint. During this phase, medial tension and lateral compression forces are applied to the elbow. Acceleration is the shortest pitching phase, lasting from maximal external shoulder rotation to ball release. In this phase, the trunk rotates as the elbow extends. Maximum elbow angular velocity is comparable during fastballs, sliders, and curveballs, but it less during the change-up pitch. Velocity comes from rotation of the trunk, shoulder, and hips. Varus torque forces during this phase act to resist the valgus extension "overload" phenomenon and can contribute to posterior elbow (olecranon) impingement. Deceleration is initiated at ball release and ends when the shoulder has reached full internal rotation. The body must decelerate the arm and dissipate forces in the elbow and shoulder. Follow-through is the final phase of the baseball pitch and ends with the pitcher reaching a balanced fielding position with full-trunk rotation and the body weight fully transferred from the rear leg to the forward leg. During follow-through, the elbow flexes into a relaxed position and crosses the body. PreviousProceed to Clinical Presentation , Little League Elbow Syndrome

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Elbow and Forearm Overuse Injuries

Background

Overuse injuries of the elbow and forearm are very common in athletes.[1, 2] Any sport that subjects an athlete to repetitive elbow flexion-extension or wrist motion can cause these syndromes. A simple way to approach these syndromes is to divide them into the different pathologies. Athletes can have tendinopathies of the triceps or biceps tendons.

Although lateral epicondylitis and medial epicondylitis are both overuse injuries, they are covered individually in other articles within this journal. Pronator syndrome is covered as a distinct entity of median nerve entrapment. Radial nerve injury is also in another article.[3] This article includes injuries to the elbow capsule and olecranon area.

Overuse injuries to the forearm and elbow are very common in throwing and racquet sports.[4, 5, 6, 7, 8, 9, 10] Any activity that entails repetitive flexion-extension of the elbow or pronation-supination of the wrist can lead to overuse injuries. As the number of recreational athletes increases, the incidence of these injuries increases.[11] The physician must obtain a very comprehensive history when dealing with these injuries because a subtle finding often can determine the proper diagnosis.[7, 8, 10, 12, 13] Obtaining a vocational history is also very important because many skilled laborers or assembly line workers perform the same offending motion at work.

For excellent patient education resources, visit eMedicineHealth's First Aid and Injuries Center. Also, see eMedicineHealth's patient education articles Repetitive Motion Injuries, Sprains and Strains, and Tennis Elbow.

Related Medscape Reference topics:

Biceps Tendinopathy

Little League Elbow Syndrome

Nerve Entrapment Syndromes

Related Medscape resources:

Resource Center Exercise and Sports Medicine

Resource Center Trauma

NextEpidemiologyFrequencyUnited States

The frequency of elbow and forearm overuse injuries is difficult to determine because of the multiple comorbid states and diagnoses that are possible (see Differentials and Other Problems to Be Considered). Some of these are covered in this article.

PreviousNextFunctional Anatomy

The elbow is a complex joint that consists of 3 true joints that function as 1 joint.[1, 2] The humeroulnar joint is a modified hinge joint and allows flexion and extension. The humeroradial joint functions not only as a hinge joint to allow flexion and extension, but also as a pivot joint that allows rotation of the radial head on the capitellum. The proximal radioulnar joint allows supination and pronation to occur. The combined motion of these joints allows a range of motion from 5-150º of flexion-extension and 75º of pronation to 80º of supination. Remember that the olecranon process of the ulna sits in the humeral olecranon fossa in 20º or less of flexion.

The ligamentous structures can be divided into the lateral and medial structures.[1, 2] These ligaments are better described as thickenings of the capsule, rather than true ligaments. Of the 3 medial structures, the anterior medial collateral ligament (AMCL) is the most important, providing approximately 70% of the valgus stability of the elbow. On the lateral side, the lateral ulnar collateral ligament (LUCL) is the strongest of the 4 branches, providing varus support.

The annular ligament maintains the radial head position in the radial notch of the humerus. Dynamic stability is provided by 4 muscle groups that transverse the elbow. The biceps brachii, brachioradialis, and brachialis muscles are the major flexors of the elbow joint. The triceps and anconeus muscles achieve extension. The supinator and biceps brachii muscles provide supination. Pronation is achieved through the pronator quadratus, pronator teres, and flexor carpi radialis muscles.

Understanding where the 3 major nerves cross the elbow is also very important. Overuse injuries or direct trauma can affect these nerves. The median nerve crosses the joint medially between the 2 heads of the pronator muscle and consists of fibers from the C5-T1 spinal nerves. The ulnar nerve travels posterior to the medial epicondyle in the cubital tunnel, down the posterior medial side of the forearm and crosses the wrist in the Guyon canal. This nerve is composed of fibers from C8 and T1 spinal nerves.[14] The radial nerve crosses the elbow laterally and branches into the superficial (sensory) and posterior interosseous nerve, which is purely motor in innervation. This branch goes deep through the arcade of Frohse, which is a common site of entrapment. The radial nerve is made up of branches from the C5-C7 spinal nerves.

PreviousNextSport-Specific Biomechanics

Repetitive elbow flexion can cause biceps tendinosis or anterior capsule strain. Activity that involves forceful elbow extension can cause triceps tendinosis or posterior impingement syndrome. In addition, any activity that causes increased valgus stress on the elbow can also cause ulnar nerve injury, posterior impingement syndrome, or olecranon stress fractures. These injuries are common in throwing sports and overhead racquet sports. Sports that require a great deal of wrist flexion-extension or pronation-supination can lead to pronator syndrome or radial tunnel syndrome. Posterolateral rotatory instability is seen only after a posterior elbow dislocation.

Related Medscape Reference topics:

Biceps Tendinopathy

Imaging of Elbow Fractures and Dislocations in Adults

Little League Elbow Syndrome

Nerve Entrapment Syndromes

Ulnar Nerve Entrapment

Related Medscape resources:

Resource Center Exercise and Sports Medicine

Resource Center Trauma

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Elbow Dislocation

Background

Elbow dislocation is the most common dislocation in children; in adults, it is the second most common dislocation after that of the shoulder.[1, 2, 3, 4, 5] The elbow is amazingly stable, relying more on bony anatomy configuration for stability rather than ligaments. Considerable force is necessary to dislocate the elbow; sports activities account for up to 50% of elbow dislocations, and this type of injury is more commonly seen in adolescent and young adult populations (see the image below).

Posterior and lateral dislocation of the left elbow in a soccer goalie. A small avulsion fracture of the olecranon is present.

Posterior elbow dislocations comprise over 90% of elbow injuries. Early recognition of this injury is required due to the need for early reduction, given a higher likelihood for poor function and possible neurovascular compromise with delays in reduction.[1, 2, 3, 4, 6, 7] Associated fractures are not infrequent with elbow dislocations, given the force that is required to dislocate the elbow.

Anterior dislocations are seen much less commonly than posterior dislocations. Divergent dislocations, which result in the ulna and radius dislocating in opposite directions, are even more rare. In the pediatric population, radial head subluxation is the main cause of elbow dislocations.

For excellent patient education resources, visit eMedicineHealth's First Aid and Injuries Center. Also, see eMedicineHealth's patient education articles Elbow Dislocation and Broken Elbow.

NextEpidemiologyFrequencyUnited States

The rate of elbow dislocation is 6-13 cases per 100,000 people, and this injury occurs more frequently in males than in females. Of all elbow dislocations, 10-50% are sports related. More than 90% of elbow dislocations are posterior dislocations.

PreviousNextFunctional Anatomy

The elbow is primarily a flexion-extension hinge joint, which also allows for pronation and supination. Normal range of motion (ROM) at the elbow should be extension to 0° and flexion to 150°.[1, 2]

The humerus and ulna form a very stable unit, which is generally resistant to disruption unless considerable force is applied. This inherent stability also reduces the likelihood of redislocation. The primary bony stabilizers are the coronoid and radial head.

The medial collateral ligament (MCL) and lateral collateral ligament (LCL) comprise the ligamentous stability of the elbow and act as a back-up system to the elbow's natural bony stability. The MCL consists of 3 bands, the anterior oblique, posterior oblique, and the transverse. The anterior band provides most of the resistance to valgus stress. The LCL has 2 bands, the ulnar collateral and radial collateral.

The 2 main compartments of the elbow are the anterior and posterior compartments. The anterior compartment contains the brachial artery and the ulnar and median nerves. This compartment is more commonly affected by dislocations and is the reason for clinical concern regarding brachial artery disruption and median or ulnar nerve entrapment.[1, 2, 4, 8]

The ulnar nerve passes posteriorly to the medial epicondyle of the humerus, and then it travels deep in the forearm before becoming more superficial again at the wrist. The close proximity of the ulnar nerve to the medial epicondyle allows for the increased likelihood of entrapment when a dislocation occurs. The median nerve is also frequently affected and travels intimately with the brachial artery, which predisposes to simultaneous injury for both the artery and nerve. The posterior compartment contains the radial nerve and triceps brachii muscle.

Anatomically, the mechanism for elbow dislocations is believed to occur as a continuum of damaged/torn structures, beginning laterally with the ulnar portion of the LCL, followed by complete LCL disruption, then damage to the anterior and posterior compartments. The posterior MCL can then become damaged, leaving the anterior portion intact. Further force can allow the elbow to pivot about the anterior bundle of the MCL, potentially damaging it. The LCL, therefore, is considered to be the initial weak link in elbow dislocations.

In the pediatric population, the clinician should be aware of the 6 ossification centers of the elbow joint as well as the annular ligament. The capitellum, radial head, internal (medial) epicondyle, trochlea, olecranon, and external (lateral) epicondyle (CRITOE) is the order in which the ossification centers appear. These centers may often be mistaken for fractures on x-rays. NOTE: A general rule of thumb for the time of appearance of the ossification centers is "1-3-5-7-9-11," which are the ages in years, corresponding to the CRITOE pneumonic.

In cases in which there is radial head subluxation, the radial head slips under the annular ligament and becomes trapped.

PreviousNextSport-Specific Biomechanics

Biomechanically, no single sport definitively increases the risk of elbow dislocations; however, sports that increase the likelihood of a person falling onto an outstretched hand (ie, FOOSH injury) (eg, gymnastics, rollerblading, cycling) may theoretically increase the risk of elbow dislocation.

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