Medial epicondyle fractures are relatively common injuries in children and adolescents accounting for up to 20% of fractures about the elbow.1 The injury may occur as a result of a fall onto an outstretched upper extremity with the elbow in extension and the wrist and fingers in hyperextension.2 This injury mechanism is commonly associated with an elbow dislocation and thus additional capsular injury.3,4 Another common mechanism occurs as the result of an avulsion type injury through pull of the forearm flexors or the medial ulnar collateral ligament (UCL). This is most common in the overhead athlete.
According to Little League, approximately 2.4 million children around the world participate in baseball each year.5 Baseball players and other overhead athletes place significant valgus stress on the elbow during overhead activities.6–8 Because the medial epicondyle contains many of the structures that resist this valgus stress, bony union of the medial epicondyle at its normal anatomic site is likely important for maintaining proper elbow biomechanics and thus sports performance in these athletes. The goal of this paper is to review the anatomic and biomechanical implications of a medial epicondyle fracture in an overhead athlete and discuss evaluation and treatment options for these injuries in this specific patient population.
The medial epicondyle is the third of 6 main ossification centers about the elbow to appear, usually developing at approximately 4 to 6 years of age. However, it is usually the last ossification center about the elbow to fuse and an open apophysis can often be present at the medial epicondyle until around 14 to 15 years of age. Because the apophyseal cartilage is relatively weaker than the tendons or ligaments that attach to it, an open medial epicondyle apophysis may predispose this area to injury. The medial epicondyle lies slightly posterior to the mid-sagittal plane of the distal humerus and serves as the anatomic origin of the flexor-pronator mass, which provides dynamic stability to valgus stress of the elbow.2,9,10 It also serves as the proximal attachment site of the UCL, which serves as the primary static stabilizer to valgus stress.11 The UCL is comprised of 3 components or bundles: the anterior oblique, posterior oblique, and transverse ligaments. The anterior oblique bundle resists most of the valgus stress throughout both flexion and extension. The anterior bands of the anterior oblique bundle are more taught during extension whereas the posterior bands are more taught during flexion (Fig. 1). The posterior oblique bundle is fan shaped and attaches more proximally on the olecranon and is taught only in flexion. The posterior oblique bundle contributes minimally to valgus stability of the elbow. The transverse ligament does not contribute significantly to valgus stability of the elbow.7,8,12 Finally, the ulnar nerve lies posterior to the medial epicondyle as it courses distally toward the flexor carpi ulnaris muscle belly.
For normal daily activities there are little functional consequences to mild variations in valgus laxity at the elbow. However, during overhead activities, especially throwing, tremendous rotational torque is transmitted to the elbow and minor variations in stability can have significant effects on sports performance and long-term elbow function. In the adult elbow, it has been estimated that the force transmitted to the elbow should tear the medial UCL with every pitch thrown >80 miles/h.13,14 Dynamic stabilization of the adult elbow through the flexor-pronator musculature likely plays a significant role in shielding the medial UCL from this stress. Activation of these muscles is also necessary to continue to transmit the force out to the fingers and ultimately the ball. In the skeletally immature overhead athlete, all of the static force restrained by the medial UCL and the dynamic force applied by the flexor-pronator musculature is transmitted through the open medial epicondyle apophysis.
During the throwing motion, most of the valgus torque resisted at the elbow is from late cocking through the acceleration phase when the elbow is in a flexed position. Because displacement of a medial epicondyle fracture changes the position of the medial UCL relative to the axis of rotation of the elbow, if a medial epicondyle heals in an anteriorly displaced position, the medial UCL will be loose in flexion and tight in extension (Fig. 1). Valgus laxity during throwing significantly affects sports performance. Laxity in flexion places additional stress on the secondary restraints, such as the radiocapitellar or the posteromedial ulnotrochlear articulations and can lead to additional long-term damage in the elbow. Depending on the degree of distalization that accompanies the anterior displacement, tightness in flexion may ultimately block range of motion by limiting full extension (Fig. 1).
In patients with a suspected medial epicondyle fracture, a careful history and physical exam should be performed. Details following an acute injury should include the timing and mechanism of injury, the location of symptoms, history of prior treatment, and the presence of any associated injuries. Associated symptoms such as joint instability, reduced range of motion, or neurological symptoms (particularly in the ulnar nerve distribution) should also be assessed. High-energy traumatic medial epicondyle injuries with an associated elbow dislocation represent a different constellation of associated injuries compared with a pure avulsion type injury from throwing. Elbow stability should be assessed during reduction of traumatic injuries. For avulsion type injuries, the history should include details about the patient’s workout regimen, changes in performance level, and timing of symptoms during performance. Pain at the medial elbow during the late cocking or acceleration phase of throwing is common in overhead athletes with valgus instability or medial epicondylitis. Ulnar nerve symptoms are also common in athletes with valgus instability due to traction of the ulnar nerve or friction along the medial epicondyle and cubital tunnel.7,15
Examination after an acute elbow injury should include a thorough skin examination taking note of swelling, ecchymosis, joint effusion, skin breaks, or gross deformity. Palpation of the elbow should note specific location of pain about the bony landmarks. Palpation should include the flexor-pronator mass, ulnar nerve, and UCL in patients with medial elbow pain. A careful neurovascular exam should be performed and any deficits noted in the distal extremity, especially when there is concern for fracture or dislocation.
Radiographic exam should initially consist of plain radiography. In skeletally immature patients, the medial epicondyle ossification center is often spherical or oval shaped. Fragmentation or multicentric ossification may be a normal variant and contralateral elbow films (especially bilateral external oblique radiographs) may be useful for comparison.9 The valgus gravity stress view of the elbow may be useful in assessing fracture displacement and elbow joint stability but is rarely tolerated in the setting of an acute injury.8,12 This view may show widening of the medial joint space or further displacement of the medial epicondyle. Once the diagnosis has been established, additional radiographs or other studies may then be obtained to further define the injury pattern. These are discussed in more detail in subsequent sections.
Controversy exists regarding the optimal treatment of medial epicondyle fractures in children. There is general consensus that nondisplaced fractures can be treated nonoperatively with a short period of immobilization followed by early range of motion to prevent stiffness.2 In addition, there is usually consensus that an incarcerated fragment within the elbow joint or an open fracture requires operative intervention.2 However, the evaluation and treatment of nonincarcerated but displaced medial epicondyle fractures in children is the topic of significant debate. There is literature to support both nonoperative and operative treatment of this injury but there is a lack of high-quality comparative studies to definitively conclude one treatment’s superiority over the other.16–28
Controversies in Radiographic Evaluation
In cases where the optimal treatment is not clear, fracture displacement is often used for decision-making. However, defining displacement is, in and of itself, a point of debate. Pappas et al29 showed that the interobserver reliability of measuring medial epicondyle fracture displacement is low. In this study, 5 raters measured medial epicondyle fracture displacement on AP, lateral, and oblique elbow radiographs. The authors showed that the raters disagreed an average of 54%, 87%, and 64% of the time on AP, lateral, and oblique radiographs, respectively. The authors cautioned against making treatment decisions based solely on the amount of fracture displacement on standard radiographs. Edmonds30 also showed that the displacement of medial epicondyle fractures is poorly estimated with plain radiography. In this study, the displacement measured on plain radiographs significantly underestimated the amount of both medial and anterior displacement seen on 3-dimensional computerized tomography scan.30 Gottschalk et al31 showed that a 45-degree internal oblique radiograph is better at estimating displacement of medial epicondyle fractures. The authors also showed, however, that this view still underestimates the amount of true displacement. Souder et al32 evaluated a novel method of assessing medial epicondyle fracture displacement with plain radiography. In a cadaveric study, the authors described a distal humerus axial view for assessing fracture displacement. They showed that measuring displacement with this technique more closely estimated the true amount of displacement (average 1.5 mm of error for fractures <10 mm displaced and average 0.8 mm of error for fractures >10 mm displaced). In addition, the authors showed that the intraclass correlation coefficient when measuring displacement was higher for axial radiographs compared with both AP and internal oblique radiographs. The advantage of the axial view is that it may estimate the amount of anterior displacement. However, the axial view has not been validated in clinical studies so its usefulness in clinical practice remains unclear.
Because the medial epicondyle serves as the origin of the flexor-pronator mass, fracture displacement usually occurs in line with the pull of this deforming force. Using a validated computer simulation model based on the biomechanics of the elbow and involved musculature, Edmonds et al33 confirmed that the most likely direction of displacement of medial epicondyle fractures is indeed anterior. The authors also showed that there is a potential for strength loss with displaced medial epicondyle fractures. In their model, anterior displacement resulted in muscle shortening and decreases in strength with each millimeter of displacement (maximum strength decrease of 39% with 20 mm of displacement). This may have important clinical implications in overhead athletes who require optimal forearm flexor strength to help dynamically stabilize the medial elbow.34,35 In addition, anterior displacement shortens the effective length of the medial UCL and may lead to static valgus instability at the elbow with high-level overhead activities.
With this in mind, some have advocated a lower threshold for operative management in the upper extremity of overhead athletes with the goal of restoring the native anatomy of the UCL complex and flexor-pronator mass to prevent elbow instability and weakness in these patients with high functional demands.24,36 There are few clinical studies, however, showing superiority of either operative or nonoperative treatment for these injuries.
Controversies in Treatment of the Overhead Athlete
Osbahr et al37 reviewed their experience treating acute medial epicondyle fractures sustained during overhead throwing in youth baseball players. The authors treated these patients with a standardized treatment algorithm: nonoperative treatment for fractures displaced ≤5 mm and without valgus instability; nonoperative versus operative treatment based on patient/surgeon preference for fractures displaced 5 to 10 mm; and operative treatment for fractures displaced >10 mm. A total of 8 patients were included in their study (5 treated nonoperatively and 3 treated operatively). All patients were able to return to play at an average of 7.6 months. The authors state that players may be successfully managed and return to play in less than a year when treated utilizing the above treatment algorithm.
Lawrence et al18 reviewed their experience with 20 child or adolescent athletes who sustained a medial epicondyle fracture and were treated either operatively (14 patients) or nonoperatively (6 patients). There were a total of 14 overhead athletes (7 baseball pitchers) in this series and all the patients were able to return to their sport at the next appropriate level regardless of the type of treatment. All the patients were either mostly or completely satisfied with their method of treatment.
Kamath et al28 systematically reviewed operative versus nonoperative treatment of medial epicondyle fractures in children. The authors showed a 9.33 times greater odds of radiographic union with operative treatment compared with nonoperative treatment although there was no significant difference between operative and nonoperative treatment in terms of pain or ulnar nerve symptoms at final follow-up. This study was limited by the heterogeneity of the reviewed literature in terms of operative indications, outcomes evaluations, and cataloging of complications. Despite its limitations, the authors advocate for strong consideration of operative management of these injuries especially in the “high demand” patient to achieve bony union.
To date, there is no clear advantage of operative over nonoperative treatment for displaced medial epicondyle fractures and the literature is rife with retrospective studies showing advantages and disadvantages to both types of treatment. Historically, advocates for nonoperative treatment of these injuries report relatively good function and low rates of symptomatic nonunion with the potential for late operative treatment in those who remain symptomatic.16,17,19–21,38,39 However, with the rise of youth sports participation, there is an increasing concern for optimal treatment of these injuries, especially in the overhead athlete.13,40,41 As such, there is a need for higher quality, prospectively collected data, with a standardized method of preoperative and postoperative evaluation, to determine the optimal treatment of these injuries in this patient population.
AUTHORS’ PREFERRED TREATMENT
A number of factors must be taken into consideration when recommending treatment for medial epicondyle fractures. Figure 2 describes the treatment algorithm used by the authors to aid in decision-making in these cases. Ultimately though, in the absence of absolute surgical indications, we advocate shared decision making with the patient and his/her family when considering treatment for these injuries.
Nonoperative treatment is considered for nondisplaced or minimally displaced fractures without signs or a history of gross instability and injuries occurring from a low-energy mechanism (ie, fall from a standing height or a pop experienced during overhead activity). Nonoperative treatment consists of a period of elbow immobilization in a long arm cast at 70 to 90 degrees of elbow flexion and neutral forearm rotation for 2 to 4 weeks. Patients are then transitioned to a removable posterior splint and encouraged to perform gentle passive elbow flexion and extension range-of-motion exercises out of the splint 3 to 5 times per day. Patients are evaluated every 2 to 4 weeks and active range-of-motion exercises are initiated once there is no tenderness to palpation of the medial epicondyle. Patients are usually transitioned to a hinged elbow brace about 6 to 8 weeks after injury to allow full motion but protect against valgus stress at the elbow. Physical therapy is initiated at 6 to 8 weeks from the initiation of treatment if full range of motion has not been attained. Forearm flexor strengthening is limited until bony union has been identified.
Operative treatment consists of open reduction and internal fixation (ORIF) and is generally recommended for those who have a history of elbow dislocation (Fig. 3), valgus instability/laxity, or for those who suffered an injury from a high-energy mechanism (ie, fall from a height, trampoline injury, motor vehicle crash, high-speed sports collision). Elbow laxity can be assessed following closed reduction under sedation if performed. Stress radiographs can also be obtained at this time if there is any question about elbow stability (Fig. 4). However, these maneuvers are rarely tolerated in the acute injury setting in the awake patient so clinical decisions are usually made based on the history of a high-energy mechanism or a known elbow dislocation. Displacement is initially assessed on the plain radiographs used to establish the diagnosis, including AP, lateral, internal, and external oblique views. If there is any question about the surgical indications at this point, an axial view is next attempted to help determine the degree of anterior displacement. Three-dimensional imaging with computerized tomography or magnetic resonance imaging is then considered for any fracture where the injury or the degree of fracture displacement remains in question.
To help relate the degree of displacement to the size of the elbow, assessment of anterior displacement is usually done as a fraction of the position of the medial epicondyle relative to the fracture bed. Fractures displaced <25% can usually be successfully treated without surgical fixation. Fractures that are displaced >75% are usually indicated for surgical fixation. For fractures in the intermediate range, 25% to 75% displaced, ORIF is generally recommended for “high demand” patients (upper extremity or overhead athlete). For the nonoverhead athlete with an intermediately displaced fracture without an associated instability event during the injury, consideration can be given for nonoperative management.
When performing ORIF, the authors utilize a technique similar to that described by Glotzbecker et al42 in which the patient is placed in the prone or sloppy lateral position (Fig. 5). This position offers distinct advantages over supine positioning when treating medial epicondyle fractures. To access the medial side of the elbow in the supine position, the surgeon must externally rotate the patient’s shoulder. This puts a valgus and external rotation force on the elbow, which will tend to displace the medial epicondyle fracture further and make accurate reduction more difficult. With the patient in the lateral or prone position, the shoulder and elbow are internally rotated. This places a varus and internal rotation moment across the elbow, which helps the joint stay reduced and aids in fracture reduction. It also promotes forearm pronation and wrist flexion, which relax the flexor/pronator mass and increase mobility of the medial epicondyle fragment (Fig. 6). Once reduced, the fracture is usually stabilized with a 4.5 mm cannulated screw with or without a washer (depending on the amount of fracture comminution). A nonabsorbable suture can also be used to capture the tendinous portion of the flexor-pronator mass. This suture can then be tied around the screw to provide further stability and backup fixation during fracture healing. The periosteum is repaired to help with rotational control. In older patients approaching skeletal maturity, before reduction, the medial epicondyle fracture bed as well as the undersurface of the medial epicondyle is denuded of any residual apophyseal cartilage. This will facilitate postoperative evaluation of radiographic union. Postoperatively, patients are immobilized at 70 to 90 degrees of elbow flexion and neutral forearm rotation for about 10 to 14 days. Once the surgical wound is stable, a protected range-of-motion protocol is initiated which is similar to those treated nonoperatively. Patients are transitioned to a hinged elbow brace at about 6 to 8 weeks postoperatively to allow full range of motion but protect the elbow from varus and valgus stress. Forearm strengthening can be initiated once good bony healing has been seen on radiographs. Patients are allowed to gradually return to sport once they are pain free, have full elbow/forearm strength and range of motion, and have evidence of radiographic union. Overhead athletes can work on the rest of the kinetic chain while recovering from their elbow injury.
The evaluation and treatment of medial epicondyle fractures in children and adolescents remains challenging. With the rise in youth sports participation, the ideal treatment of these injuries is especially important in this high demand patient population. There continues to be room for improvement in how these injuries are evaluated, particularly with regards to radiographic evaluation. Assessment of anterior displacement may be the key to understanding the biomechanical implications in a throwing athlete. Future investigation evaluating patient outcomes after appropriately designed comparative studies will be important to determine the optimal treatment strategy.
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Keywords:Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
medial epicondyle; overhead athlete; thrower treatment