➢ Most elbow injuries occur as a result of the stresses incurred during the acceleration phase of throwing.
➢ During overhead throwing, a large valgus force on the elbow created by humeral torque is countered by rapid elbow extension, creating substantial tensile stress along the medial compartment, shear stress in the posterior compartment, and compressive stress in the lateral compartment.
➢ Repetitive valgus loading resulting from overhead throwing in skeletally immature patients can lead to fragmentation or avulsion of the medial epicondylar apophysis.
➢ Injury to the flexor pronator mass can be traumatic or attritional, but before it is assumed that the injury involves the flexor pronator mass and will respond to conservative measures, injury to the ulnar collateral ligament must be ruled out.
Overhead throwing athletes place a substantial amount of stress on the elbow during the throwing cycle. In athletes such as baseball players, repetition leads to attritional damage to the elbow. While injury to the medial ulnar collateral ligament is the most publicized, and perhaps most important, of these conditions, a collection of other disorders commonly afflict this population. These injuries include (1) ulnar neuritis, (2) flexor pronator injury, (3) medial epicondylar apophysitis or avulsion, (4) valgus extension overload syndrome with posterior impingement, (5) olecranon stress fractures, and (6) osteochondritis dissecans of the capitellum1.
The purpose of the present review article is to describe the biomechanics of the throwing motion and the diagnosis and treatment of elbow injuries common to a thrower other than injuries to the ulnar collateral ligament.
The osseous anatomy of the proximal part of the ulna and the olecranon fossa provides primary stability at <20° and >120° of flexion. The radial head provides secondary restraint to valgus stress at 30°. The primary coronal stability during the functional arc of an overhead athlete (20° to 120°) emanates from the soft-tissue restraints2-4.
The soft-tissue structures that provide the static valgus elbow stability that is vital to overhead throwing include the anterior joint capsule, the ulnar collateral ligament complex, and the radial collateral ligament complex. The ulnar collateral ligament is composed of three bundles: anterior, transverse oblique, and posterior.
The dynamic elbow stabilizers consist of the muscles in the flexor pronator mass that originate off the medial epicondyle, which functionally stabilize the elbow against valgus stress during active motion5. These muscles include the flexor carpi radialis, flexor carpi ulnaris, flexor digitorum profundus, flexor digitorum superficialis, flexor pollicis longus, and pronator teres.
Last, the ulnar nerve borders the medial aspect of the elbow joint, emanating from the arcade of Struthers and passing into the posterior compartment of the arm through the medial intermuscular septum (Fig. 1). It curves around the medial epicondyle superficial to the ulnar insertions of the posterior and oblique bundles of the ulnar collateral ligament and nearly parallel to the anterior bundle at the level of the ulnohumeral joint.
Biomechanics of Throwing
The throwing motion of a baseball pitcher, which is the most heavily investigated model, serves as the basis for understanding biomechanics. The baseball pitch is divided into six stages of coordinated upper extremity, trunk, and lower extremity movements (Fig. 2)6-9.
Most elbow injuries occur as a result of the stresses incurred during the acceleration phase, during which valgus torque reaches as high as 64 Nm10. Nearly 300 N of shear force is experienced by the medial aspect of the elbow10. Concomitantly, compressive forces at the radiocapitellar joint reach 500 N10.
Pathophysiology of Elbow Injuries
During overhead throwing, a large valgus force on the elbow that is created by humeral torque is countered by rapid elbow extension, creating substantial tensile stress along the medial compartment, shear stress in the posterior compartment, and compressive stress in the lateral compartment (Fig. 3)10,11. This spectrum of pathophysiology is known as valgus extension overload syndrome12. Repetitive, near-failure tensile stresses create microtrauma and attenuation of the ulnar collateral ligament, leading to progressive valgus instability. As the ulnar collateral ligament becomes incompetent, the osseous constraints of the posteromedial aspect of the elbow become important stabilizers during throwing. Continued shear stress and impingement in the posterior compartment lead to olecranon tip osteophytes, loose bodies, and articular damage to the posteromedial aspect of the trochlea in the continuum of valgus extension overload syndrome. Subtle laxity in the ulnar collateral ligament also leads to stretching of and pathological changes in the other medial structures, including the flexor pronator mass and the ulnar nerve.
History and Physical Examination
Asking the athlete specifically about the chief complaint may help to delineate between clinically important processes (i.e., valgus instability) and less important processes (i.e., flexion contracture). Complaints may include pain, decreased motion, mechanical symptoms (clicking, locking, popping, etc.), instability, paresthesias, and throwing-specific symptoms.
Physical examination starts with inspection of skin for prior incisions, muscle mass for atrophy, and the position of the arm at rest. Resting elbow flexion of approximately 70° allows the greatest intracapsular volume and may be an indication of effusion13. Flexion of up to 20° may be secondary to an extension block resulting from posteromedial olecranon osteophytes.
Tenderness of osseous landmarks may indicate acute fracture, stress fracture, or tendinitis. In the skeletally immature athlete, tenderness may indicate injury to the apophysis or physis. Lateral olecranon tenderness may indicate a stress fracture, whereas proximal-medial olecranon tenderness may be related to impingement. Last, palpation of the radial head during an arc of passive supination and pronation can help to identify osteochondral defects, joint incongruency, and injury to the annular ligament.
Tenderness over the insertions of the various tendons around the elbow can indicate microtrauma or inflammation. The origin of the flexor pronator mass lies just anterior to the medial epicondyle when the elbow is at 90° of flexion. Having the patient actively flex the wrist will tension the common origin and will help to identify the tendinous mass, accentuate any pain, and differentiate the flexor pronator mass from ulnar collateral ligament abnormality.
Posterior and distal to the medial epicondyle lies the cubital tunnel, which encloses the palpable ulnar nerve. Percussion of the nerve resulting in radiating symptoms into the ulnar aspect of the hand and the ulnar two digits (Tinel sign) may indicate ulnar nerve pathology, but the sensitivity and specificity of this test have been reported to be as low as 44% and 68%, respectively14. Meanwhile, a combination of the elbow flexion test and direct pressure over the ulnar nerve was found to have 91% sensitivity15. Ulnar nerve subluxation should be assessed with pressure over the nerve through the range of elbow motion, with care being taken to differentiate ulnar nerve subluxation from snapping of the medial head of the triceps16,17.
Last, with the patient in the seated position and the forearm supinated, the elbow is slightly flexed. With one hand on the posterior aspect of the distal part of the humerus and the other hand on the volar aspect of the forearm, the elbow is rapidly extended while a valgus stress is applied (Fig. 4)12. Pain on this valgus extension overload test indicates impingement of the posteromedial tip of the olecranon on the medial wall of the olecranon fossa.
Standard anteroposterior, lateral, and oblique radiographs of the elbow are made. Radiographs may demonstrate calcification, olecranon fossa osteophytes, sclerotic osteochondritis dissecans lesions, and/or loose bodies.
Computed tomography (CT) can help identify stress fractures (Fig. 5), but it is not sensitive for detecting stress injuries in their early stages and may not be indicated for skeletally immature patients given the risk of radiation exposure compared with the potential information obtained18.
Magnetic resonance imaging (MRI) is the imaging modality of choice for the evaluation of the elbow in throwing athletes and can detect early stress changes as well as muscle and tendon changes, ulnar collateral ligament tears, loose bodies, osteochondral injuries, olecranon osteophytes, and neurovascular changes19.
The ulnar nerve is susceptible to several mechanical factors in throwing athletes, including compression, traction, and irritation of the nerve (Fig. 1 and Fig. 6). Additional sites of compression include hypertrophic muscles in throwers, such as the anconeus epitrochlearis and the medial head of the triceps20,21.
Athletes with chronic valgus instability may experience traction neurapraxia22. Moreover, athletes with medial epicondylitis are also susceptible to the development of ulnar nerve symptoms22-24. Osteophytes resulting from valgus extension overload and friction resulting from ulnar nerve subluxation can serve as underlying etiologies as well25.
Pechan and Julis found the pressure in the nerve within the cubital tunnel to be three times the resting level when the elbow was flexed and the wrist was extended26. Continuation of the throwing motion with further elbow flexion and shoulder abduction causes the intraneural pressure to rise to six times the resting level. This increased pressure is attributed to nerve stretch, tightening of the cubital tunnel, and compression27. Repetitive motions can induce chronic changes to the ulnar nerve and surrounding soft tissues, potentially leading to nerve fibrosis and ischemia.
The elbow flexion test with the elbow maintained in maximum flexion and the wrist maintained in extension for one minute should be conducted. Monofilament testing can detect early sensory changes.
Electrodiagnostic testing may be useful for diagnosing ulnar neuropathy; however, changes may not be seen until disease has advanced.
Nonoperative treatment typically begins with activity restriction, anti-inflammatory drugs, cryotherapy, and physical therapy. Ulnar subluxation or dislocation may require a brief period of immobilization in a posterior splint at 90° to prevent excessive flexion and tension on the nerve.
The indications for operative treatment include the failure of nonoperative treatment, persistent ulnar nerve subluxation, traction neurapraxia, and concomitant medial elbow problems that require surgery27. The options for surgical treatment include in situ decompression of the ulnar nerve, medial epicondylectomy, and anterior transposition of the nerve (submuscular, intramuscular, or subcutaneous). While in situ decompression addresses external compression, it fails to address irritation resulting from traction, particularly in the setting of valgus instability, and fails to stabilize a subluxating or dislocating nerve. Potential complications of medial epicondylectomy include valgus instability resulting from iatrogenic injury to the anterior aspect of the ulnar collateral ligament, nerve instability, tenderness, and weakness resulting from disruption of the flexor pronator mass28-32.
Anterior transposition of the ulnar nerve is the mainstay of surgical treatment of ulnar neuritis. Subcutaneous transposition has the advantage of less surgical morbidity to the flexor pronator mass and may be recommended for patients undergoing concomitant ulnar collateral ligament reconstruction33-35. The disadvantages of the subcutaneous technique include the risk of direct trauma and the potential for the development of instability and/or the recurrence of symptoms resulting from new compression under the subcutaneous fasciodermal sling23,36,37. Anterior submuscular transposition deep to the flexor mass involves greater surgical dissection in the medial soft tissues and a lengthier postoperative rehabilitation course but provides thorough decompression of the nerve while protecting it from direct and indirect trauma.
Rettig and Ebben performed twenty-one anterior subcutaneous transposition procedures in twenty athletes after the failure of nonoperative treatment of cubital tunnel syndrome34. All athletes returned to play at an average of 12.6 weeks. Eaton et al. reported relief of symptoms in thirteen of fourteen patients, seven of whom were baseball pitchers who returned to sport38. The authors recommended subcutaneous transposition in light of faster postoperative recovery and rehabilitation. However, some authors have criticized this technique because of the potential for persistent symptoms. Del Pizzo et al. reported their findings in a study of nineteen baseball players who underwent anterior submuscular ulnar nerve transposition for the treatment of recalcitrant ulnar neuritis17. Nine (60%) of the fifteen athletes who were evaluated at three to fifty-eight months postoperatively were able to return to play.
Flexor Pronator Injury
An acute complete rupture of the common flexor pronator origin is relatively uncommon; rather, overhead throwing athletes may have development of mild muscular overuse, chronic tendinitis, or acute partial muscle tears (Fig. 7)39. Repetitive contraction of the flexor pronator muscles causes medial elbow pain during the acceleration phase of throwing as well as with wrist flexion during ball release8.
The main differential diagnosis includes injury to the ulnar collateral ligament. Tenderness anterior to the midline of the medial epicondyle is consistent with flexor pronator injury, whereas posterior tenderness may be the result of ulnar collateral ligament injury. Nevertheless, clinical differentiation between these two entities can be difficult, and MRI will aid in diagnosis. Combined ulnar collateral ligament and flexor pronator injuries are not uncommon. Osbahr et al. found that an age of more than thirty years was a risk factor for the development of a combined injury and carried a poor prognosis when compared with isolated ulnar collateral ligament injuries40. Patients with combined injuries had a 12.5% rate of return to play after surgical reconstruction of the ulnar collateral ligament.
Overuse tendinitis and partial tears of the flexor pronator muscle mass (both attritional and traumatic) can be treated with active rest, ice, anti-inflammatory medications, physical therapy (including eccentric exercises, laser therapy, and extracorporeal shockwave therapy), and gradual return to throwing41-43. Active rest involves reestablishing a nonpainful range of motion during a period of rest from throwing until symptoms subside. Corticosteroids are generally avoided given the proximity of the ulnar collateral ligament. To our knowledge, no data are available on the efficacy of platelet-rich plasma injections for the treatment of flexor pronator injury in overhead throwing athletes. Complete ruptures of the flexor pronator origin require prolonged rest and rehabilitation. Splinting of the wrist in the neutral position may alleviate acute pain during the first seven to ten days after injury. Rehabilitation, with an emphasis on range of motion followed by resistance training, is necessary before interval throwing is initiated. If pain or weakness recurs with throwing, then operative repair may be necessary.
Overhead throwers are also vulnerable to pronator syndrome, a rare condition that is due to compression of the median nerve resulting from hypertrophy of the pronator teres secondary to repetitive activity44-46. Athletes complain of vague, fatigue-like pain over the proximal part of the volar aspect of forearm that is exacerbated by resisted forearm pronation and wrist flexion.
Medial Epicondyle Avulsion or Apophysitis
Bennett coined the term Little League elbow to describe the medial-sided stress injuries that can occur in skeletally immature throwing athletes47. Medial epicondyle avulsion injury and apophysitis are the most common injuries and are quite prevalent in youth baseball. Hang et al. found that 180 (52%) of 343 skeletally immature Little League players in Taiwan reported medial elbow pain or soreness at some point during the course of a season48. Apophysitis is associated with the combination of repetitive forces on the medial aspect of the elbow and inadequate intervals of rest49-51.
In cases of medial epicondylar apophysitis, radiographs may show a subtle widening of the physeal plate, and comparison radiographs of the uninvolved limb are vital. MRI typically shows more findings than radiographs; however, MRI findings do not necessarily have clinical correlation52. Treatment of apophysitis begins with prevention53. Adams evaluated eighty Little League pitchers in California who were between nine and fourteen years of age54. Radiographs of the elbow revealed medial epicondylar apophyseal fragmentation in thirty-nine (49%) of the eighty elbows. Adams recommended changes in the Little League system, including placing limitations on the season length and number of innings pitched, preventing the use of the curve ball, and dividing Little League into more age-specific competitive levels.
Initial treatment consists of extended rest and cryotherapy until symptoms resolve, followed by a gradual return to throwing. Harada et al. found that athletes who were noncompliant with pitching restrictions and who returned to rigorous activity before bone union was seen on radiographs had substantial delays in bone union at both six months and one year compared with athletes who waited to resume rigorous throwing until after complete bone union had been achieved55.
Treatment for epicondylar avulsions remains controversial56,57. For complete avulsion of the medial epicondyle, most authors56-59 recommend open reduction and internal fixation if the fragment is displaced by ≥5 mm. Nonoperative measures are sufficient for the treatment of stable minimally displaced fractures. These injuries can be treated with splint immobilization for five to seven days, followed by early motion57-59. Lawrence et al. recommended nonoperative management for young athletes with low-energy avulsion of the medial epicondyle, a stable elbow, and minimal fracture displacement (mean, 5.3 ± 2.0 mm)60. Those authors also noted that open reduction and internal fixation can be successful for athletes who have sustained more substantial trauma, those with elbow laxity or instability, and those with substantial fracture fragment displacement (mean, 7.1 ± 2.9 mm) after a fracture of the medial epicondyle.
Valgus Extension Overload Syndrome with Posterior Impingement
Valgus extension overload syndrome can occur in association with an attenuated ulnar collateral ligament, a physiologically lax elbow, or repetitive valgus stress resulting from throwing. The athlete most commonly complains of posteromedial elbow pain during the extension (late acceleration) or follow-through phase of throwing61. During these phases, the elbow subluxates and force increases in the lateral and posterior compartments2,5,7,8,62,63. Continued compressive and rotatory forces in the lateral compartment lead to synovitis and osteochondrosis of the radiocapitellar joint2,12. Posterior and posteromedial olecranon osteophytes that form as a result of impingement may fracture and contribute to loose bodies along with osteochondral fragments from the radiocapitellar joint. These throwers also may have a flexion contracture and a tendency to throw high from an early release point. Cohen et al. found a typical pattern of valgus extension overload syndrome on MRI64. In that study, all nine throwing athletes had pathological changes at the articular surfaces of the posterior aspect of the trochlea and the anteromedial aspect of the olecranon.
Initial treatment should consist of active rest with cryotherapy, iontophoresis, and anti-inflammatory drugs. As symptoms subside and motion returns to baseline, rehabilitation should include dynamic stabilization and strengthening exercises, with an emphasis on eccentric strengthening of the elbow flexors to control rapid extension of the elbow.
The indications for operative treatment include the failure of nonoperative treatment of impingement-related pain as well as the presence of loose bodies within the joint. The treatment of choice in these instances is arthroscopic debridement and removal of loose bodies12,47,65. Ulnar collateral ligament reconstruction may be needed if concomitant valgus instability is present.
Reddy et al. reported on 187 arthroscopic procedures in 172 patients66. The most common diagnosis was posterior impingement (51%), followed by loose bodies (31%) and degenerative joint disease (22%). Forty-seven (85%) of the fifty-five professional athletes returned to the previous level of competition. There were three transient complications, one of which was related to the ulnar nerve. Fideler et al. reported excellent results in a study of 113 professional baseball players who underwent arthroscopic treatment of posterior impingement and loose bodies; 74% of the athletes returned to the preoperative level of sports67. However, excellent results have not been universally reported. Andrews and Timmerman evaluated fifty-six professional baseball players who underwent arthroscopic excision of olecranon osteophytes68. Twenty-three (68%) of the thirty-four patients who were available for follow-up after a minimum of twenty-four months returned to play at least one season. However, fourteen (41%) required reoperation, including repeat debridement of olecranon osteophytes (six) and ulnar collateral ligament reconstruction (five). The authors cautioned against excessive olecranon excision. Resection of >3 mm of the posteromedial aspect of the olecranon jeopardizes the function of the anterior bundle of the ulnar collateral ligament as it exposes a potentially attenuated ulnar collateral ligament to higher stresses69,70. Thus, it is recommended that only the osteophytes and no native olecranon should be removed.
Olecranon Stress Fracture
Proximal olecranon stress fractures occur as a result of the repetitive microtrauma, excessive tensile stress from the triceps tendon, and posterior impingement of the olecranon against the olecranon fossa associated with competitive overhead throwing71. Typically, there is no pain at rest, and there is a gradual onset rather than a single event. Schickendantz et al. stated that pain with percussion of the proximal part of the ulna may indicate a stress fracture72. Stress fractures of the proximal part of the olecranon should be differentiated from avulsion fractures of the tip of the olecranon and from a persistent olecranon apophysis, which may be treated differently. Short tau inversion recovery (STIR) MRI shows areas of high signal intensity in the posteromedial aspect of the olecranon, consistent with bone edema and hyperemia in patients with more acute stress reactions72.
Initial treatment includes rest, immobilization, and cessation of throwing. Specifically, any valgus stress should be avoided for a minimum of six weeks. Full extension also should be avoided, with the application of a splint or orthosis that is set to approximately 20° of extension, for the first four weeks. At four weeks, full range of motion is allowed, and progressive resistance exercises of the elbow are initiated. Sport-specific rehabilitation is initiated at six weeks, and an interval throwing program typically starts at around eight weeks. Nuber and Diment successfully treated two olecranon stress fractures in competitive pitchers with splinting and cessation of throwing73. Both players had radiographic union and returned to pitching. Schickendantz et al. also successfully treated stress-related changes in seven professional athletes with use of the nonoperative measures outlined above72.
Complete olecranon stress fractures in the competitive thrower often require surgical fixation. We are aware of only one report on the surgical fixation of proximal olecranon stress fractures in baseball players74. In that study, Paci et al. performed percutaneous fixation for the treatment of proximal ulnar stress fractures in twenty-five baseball players. All eighteen fractures that were available for follow-up went on to union, with seventeen (94%) of the eighteen athletes being able to return to the preinjury level of play.
Osteochondritis Dissecans of the Capitellum
Repetitive compressive trauma, in addition to ischemia and genetics, has been implicated in the development of osteochondritis dissecans of the capitellum (Fig. 8). However, the exact etiology remains unclear. A wide spectrum of injuries—including subchondral changes, secondary osteochondrosis of the radial head, and loose bodies—can result. Morrey described a three-stage classification system for pathological progression, with stage I indicating no evidence of subchondral displacement or fracture, stage II indicating evidence of subchondral detachment or articular cartilage fracture, and stage III indicating detached osteochondral fragments, resulting in intra-articular loose bodies75. Treatment depends on the severity and stability of the osteochondral lesion. Athletes may have swelling or effusion, tenderness over the lateral aspect of the elbow, and crepitance with motion76.
Mihata et al. performed a biomechanical cadaveric study and found that osteochondritis dissecans of the radiocapitellar joint increases elbow valgus laxity and contact pressure without increasing ulnar collateral ligament strain77. They also found that contact pressures were greater in association with a lateral defect as compared with an equally sized central defect.
Nonoperative treatment should be reserved for early (Morrey stage-I) lesions and consists of a minimum six-week period of rest from throwing and valgus stress78. After pain resolves, a strengthening program is initiated, with transition to an interval throwing program. Mihara et al. reported on thirty-nine baseball players with a mean age of 12.8 years who had nonoperative treatment of osteochondritis dissecans lesions of the capitellum79. After a mean duration of follow-up of 14.4 months, twenty-five of thirty early lesions had healed, compared with one of nine advanced lesions. Sixteen of the seventeen lesions in patients with open physes healed, compared with only eleven of twenty-two lesions in patients with closed physes. Takahara et al. reported on twenty-four patients with a mean age of 13.3 years (range, eleven to sixteen years) who received six months of nonoperative treatment of capitellar osteochondritis dissecans78. After an average duration of follow-up of 5.2 years, twenty (83%) of the twenty-four patients had a fair or poor result, and there was no notable difference in outcome between young and old patients or between early and advanced lesions.
Operative intervention is limited to patients who do not respond to nonoperative treatment, those with mechanical symptoms, and those with advanced (stage-II or III) disease resulting in the development of unstable fragments within the joint. Bauer et al. reported the long-term outcomes for thirty-one patients with a mean age of twenty years80. Twenty-two of these patients had loose-body excision and one had radial head excision, and most patients (twenty of thirty-one) appeared to have advanced lesions. After an average duration of follow-up of twenty-three years, 40% of the patients had recurrence of symptoms and loss of elbow extension, with >60% of examined radiocapitellar joints demonstrating degenerative joint disease. In an initial study, Takahara et al. reported on thirty-nine patients with an average age of 17.6 years who were managed with open fragment excision81. After an average duration of follow-up of 14.7 years, 26% of the patients reported good results, and 49% had returned to full sports participation. Takahara et al. followed their initial study with another study in which sixteen patients were added to the original cohort82. The authors reported that better results in terms of pain and radiographic findings were seen in patients with lesions measuring <50% of the capitellar articular width.
Arthroscopic debridement and abrasion chondroplasty has demonstrated promising results in terms of pain relief and objective improvements in elbow range of motion in numerous short and intermediate-term follow-up studies76,83-86. Byrd and Jones examined ten patients ranging in age from eleven to sixteen years, seven of whom had advanced disease84. After an average duration of follow-up of four years, all seven advanced lesions had healed, but only four of the ten patients had returned to sport and two patients demonstrated degenerative radiographic findings. The authors found no correlation between the grade of the lesion and postoperative outcomes or return to sport. Ruch et al. reported on twelve patients ranging in age from eleven to seventeen years who were followed for a mean of 3.2 years after arthroscopic debridement of unstable elbow lesions (mean size, 2.5 cm)87. Improved extension was seen postoperatively, mechanical symptoms resolved in eleven patients, and eleven patients were highly satisfied. However, only three patients returned to sport.
Arthroscopic debridement, drilling, and microfracture also have been performed for the treatment of osteochondritis dissecans, but we are unaware of any data specific to overhead throwing athletes. Fragment fixation has been attempted through a variety of techniques and implants, with reliable results reported in small case series82,88-91.
Lateral closing-wedge osteotomy has been employed to unload the radiocapitellar joint. As the lesion is not directly addressed, this technically challenging procedure is reserved for early lesions that are stable. Kiyoshige et al. evaluated seven baseball players ranging in age from eleven to eighteen years who underwent a lateral closing-wedge osteotomy92. After seven to twelve years of follow-up, six (86%) of the seven patients had complete relief of pain with return to sport.
Osteochondral autograft transplantation is another technique for the treatment of advanced osteochondritis dissecans lesions of the capitellum. Early results have demonstrated reasonable outcomes after osteochondral autograft transplantation, but long-term follow-up of throwing athletes is needed before definitive conclusions can be drawn93,94.
Overhead throwing activities expose the elbow to tremendous valgus stress, making the athlete vulnerable to myriad injuries. The mechanism of valgus extension overload combined with the repetition of this motion in athletes can lead to many pathologic conditions in the elbow. Understanding the anatomy and function of the elbow as well as the biomechanical relationship between the two remains vital to appropriate management.
Source of Funding: No external funds were received in support of this study.
Investigation performed at the Department of Orthopaedic Surgery, The Cleveland Clinic Foundation, Cleveland Clinic Sports Health Center, Garfield Heights, Ohio
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
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