Radial Head Fractures and Dislocations

The elbow joint consists of three bones and three joints. The bones are as follows:

• Distal humerus
• Proximal ulna
• Proximal radius

The joints are as follows:

• Ulnotrochlear joint - This joint, which is between the olecranon process of the ulna and the medial condyle of the humerus, is a constrained joint that allows only flexion and extension
• Radiocapitellar joint - This joint, which is between the radial head and the lateral condyle of the humerus, is less constrained and allows both flexion and extension and forearm rotation
• Radioulnar joint - This joint, which is between the radial head and the proximal ulna, is minimally constrained and allows forearm rotation

The joints are controlled by the ligamentous anatomy of the elbow. The elbow joint (ulnotrochlear joint) is constrained by the medial collateral ligament, which has well-defined anterior, posterior, and transverse bundles. The elbow is also constrained by the lateral collateral ligament, which is poorly defined, and the radial collateral, lateral ulnohumeral, and accessory collateral ligaments provide stability. The radioulnar joint is constrained by the annular ligament.

The neurovascular structures of the elbow are easily damaged in fractures and dislocations of the elbow. The physician needs to be especially aware of the ulnar nerve proximally because it passes behind the medial epicondyle and the posterior interosseous nerve, wraps around the radial neck, and is most likely to be damaged with radial head fractures or dislocations or during surgery to correct these injuries. The median nerve and the brachial artery are in danger in the front of the elbow.

Because the radial head is intra-articular, anatomic reduction of bone fragments is necessary to minimize the risks of lateral posttraumatic arthritis from mechanical grinding. The intra-articular position also means that soft-tissue attachments to the most proximal portion of the bone are limited, and thus, fractured fragments frequently lose their blood supply, resulting in avascular necrosis and potential nonunion. Luckily, the radial head mostly acts as a spacer preventing proximal migration of the radius; as long as it maintains its structural support, the patient may do well even if the bone dies.

Except for congenital radial head dislocations, which by definition are not acquired, radial head fractures and dislocations are the result of trauma, usually from a fall on the outstretched arm with the force of impact transmitted up the hand through the wrist and forearm to the radial head, which is forced into the capitellum.

Recognizing a congenital radial head dislocation (see the image below), in which the radial head is larger and rounder than expected, is important because operative treatment to reduce a congenital radial head dislocation is not indicated.

The radial head is fractured in about 20% of cases of elbow trauma. About 33% of elbow fractures and dislocations include injury to the radial head, the radial neck, or both.

For radial head and neck fractures and dislocations, the prognosis is generally good when the following are achieved[7] :

• Mechanical stability with anatomic reduction and stable internal fixation
• Optimal biology of healing with anatomic reduction, indirect techniques, and maintenance of soft-tissue attachments

A study by Duckworth et al reported excellent long-term results with nonoperative management of isolated stable fractures of the radial head or neck.[8]

A patient with radial head fracture-dislocations usually presents with a history of a fall on the outstretched hand. Blunt or penetrating trauma rarely causes radial head injury. The wrist, especially the distal radioulnar joint, may be damaged simultaneously, and the presence of wrist pain, grinding, or swelling should be determined.

The presence of bleeding, even with small puncture wounds, should alert the examiner to the possibility of open injury. Neurovascular symptoms of numbness, tingling, or loss of sensation should be identified to rule out nerve or vascular injury. The presence of severe pain should alert the examiner to the possibility of compartment syndrome.

Patients with radial head fractures and dislocations present with localized swelling, tenderness, and decreased motion. The physician must carefully examine any wounds to make sure that no open fractures are present. Evaluating wounds over the subcutaneous border of the ulna is especially important in fracture-dislocations for ensuring that open fractures are not missed. The examiner should palpate the elbow, especially the radial head, feeling for deformity, and should also examine the wrist, especially feeling for stability of the distal radioulnar joint.

Because all three major nerves of the forearm are in danger with elbow fractures and dislocations, the examiner should also carefully assess neurovascular function for all of the nerves of the forearm and hand. Radial nerve function is especially important to assess with displaced fractures through the neck of the radius. The motor (posterior interosseous) branch provides extension for the fingers and wrist (see Anatomy).

The examiner must also assess the firmness of all compartments, check for pain with passive stretch, and measure compartment pressures if in doubt to avoid missing compartment syndromes. Elbow stability needs to be assessed even with seemingly nondisplaced radial neck fractures. The elbow is tested with valgus stress at 30° of flexion to determine the competency of the medial collateral ligament.

Most radial head injuries can be assessed adequately with standard plain radiography of the elbow. Normal radiographic examination findings demonstrate that the radial head is aligned with the capitellum on all views. A dislocation of the radial head can be easily missed if all radiographs are not carefully examined for this relation. For the normal elbow, a line drawn through the radial head and shaft should always line up with the capitellum, and with a supinated lateral view, lines drawn tangential to the head anteriorly and posteriorly should enclose the capitellum.

With a radial head dislocation, these radiographic findings are disrupted. The images below are examples of an injury that appears to be a simple ulna fracture when only the anteroposterior (AP) view is evaluated but that clearly has a dislocated radial head on the lateral view. As with any fracture assessment, two views perpendicular to each other are always required.

In rare circumstances, computed tomography (CT) of the elbow is useful to define fracture patterns.

Most radial head fractures and dislocations are well defined by the findings on clinical examination and imaging studies. If a high index of suspicion exists for an occult fracture, the joint can be aspirated. Fat globules in the fluid imply a fracture. If suspicious wounds are present and an open fracture or dislocation is suspected, the joint can be injected. If fluid comes out of the wound, then the wound is communicating with the joint.

The goal of treatment of radial head fractures and dislocations, as with all orthopedic injuries, is a successful functional outcome. A successful outcome correlates directly with accuracy of anatomic reduction, restoration of mechanical stability that allows early motion, and attention to the soft tissues. Treatment can be closed, with immediate early motion to prevent stiffness in stable fractures, or it may be open, with surgical reconstruction depending on the fracture type. Specific surgical indications are discussed below (see Surgical Therapy).

No contraindications for treatment exist. Contraindications for surgical treatment are discussed below as indications for nonoperative treatment (see Medical Therapy).

The treatment of radial head fractures and dislocations is relatively uncontroversial. Less prominent implants are being devised to decrease problems from hardware. Fixed-angle locking screw plates are gaining a role, especially when interfragmentary compression cannot be adequately achieved.

Whereas internal fixation that fixes the whole head is currently the treatment of choice, partial internal fixation (where the head cannot be fully reconstructed) may have worse results than excision or replacement in terms of elbow function but better results in terms of distal radioulnar function. The specific indications for replacement or excision versus internal fixation continue to be studied.

Radial head replacement designs, such as bipolar designs and radial head and capitellar replacements are currently available, but there have been limited studies concerning results with these designs.[9]

Treatment options for radial head fractures or dislocations include the following:

• Closed reduction with casting or early motion
• Open reduction with internal fixation (ORIF), replacement, or resection

Closed reduction and casting often has associated high rates of stiffness, and closed reduction and early motion may still have high rates of nonunion and malunion in comminuted or unstable fractures, resulting in generally poor functional results. Open treatment (involving internal fixation, replacement, or excision, depending on the fracture) is associated with better long-term function.

The condition of the soft tissues is as important as the condition of the bone in determining the eventual functional outcome (see the image below). Schatzker's general observation concerning fracture care is especially relevant for elbow injuries: "Long term disability following a fracture is almost never the result of damage to the bone. It is the result of damage to the soft tissues and stiffness of neighboring joints."[10]

An isolated radial head dislocation is almost always treated with closed reduction and early motion (see the image below). If closed reduction cannot be achieved, open reduction is indicated. Congenital radial head dislocations do not require treatment.

Nonsurgical treatment of isolated radial head fractures is indicated if minimal displacement, minimal angulation, and minimal head involvement are noted (see the image below). Early motion with a functional brace is encouraged to minimize elbow stiffness. Adequate follow-up is essential to be sure late displacement is not missed. (If displacement occurs, operative intervention is usually indicated.)

For isolated radial head fractures, the Mason classification guides treatment.[2, 4, 9, 11] This classification may be summarized as follows:

• Type I (undisplaced) - This type generally is treated nonoperatively
• Type II (single fragment displaced) - This type may be treated nonoperatively if the displacement is minimal; the rule of threes is followed, according to which nonsurgical treatment can be considered if the fracture involves less than one third of the articular surface, if there is less than 30° of angulation, and if displacement is less than 3 mm
• Type III (comminuted) - This type usually requires operative intervention but may occasionally be treated closed with early motion if the radial head is not reconstructible; if a mechanical block to motion is present, then nonsurgical treatment cannot be used ^{[2, 4, 9, 11]}

Fracture-dislocations of the radial head can rarely be treated with closed reduction and splinting, but better results are expected in most cases with operative stabilization and early motion.

Patients whose medical condition is too unstable to allow safe surgery when surgery would otherwise be indicated can also be treated with splinting followed by early motion, but the prognosis is guarded for achieving optimal function.

Joint aspiration to relieve pressure has been employed as an initial treatment measure, but its efficacy is unclear.[12]

Indications for surgery

Surgical treatment is indicated for all unstable radial head (and neck) fractures and dislocations. As described above, the rule of threes can be used for determining the need for surgical intervention: Surgery is required if the fracture involves more than 33% of the articular surface, is angulated more than 30°, or is displaced more than 3 mm. A mechanical block to motion always requires open treatment to remove the blocking bone or osteochondral fragment or fragments.

Open fractures are also surgical emergencies. They require surgical irrigation and debridement in an operating room with appropriate antibiotics even if the wound is small. At the same time, immediate stabilization of the bone injury is also performed.

Monteggia fracture-dislocations are a special variety of radial head injury. They are commonly classifed into four types (see Table 1 below).

Table 1. Classification of Monteggia fracture-dislocations (Open Table in a new window)

Classically, Monteggia fractures are ulna fractures in the proximal one third with associated radial head dislocation (see the images below). Instead of the radial head dislocation, the radial head or neck may be fractured as an equivalent injury. The injury pattern is similar to both-bone forearm fractures. Monteggia fracture-dislocations are included here because of the importance of not missing either injury. The isolated injuries (radial head dislocation by itself or ulna [nightstick] fracture by itself) are often treated by closed treatment with good results, but the combined injury can almost never be treated by closed methods if good results are expected. Appropriate treatment requires diagnosing both (see Workup, Imaging Studies).

Floating elbow injuries are another special case that can include radial head injury. Floating elbow injuries include associated ipsilateral forearm and humerus fractures. They are severe high-energy injuries. The best outcome almost always requires fixation at both levels. Standard fixation methods for the individual fractures are used (see the image below). Surgical treatment options include ORIF with plates and screws, excision of fragments, or radial head replacement.

Surgical treatment of so-called terrible triad injuries of the elbow (elbow dislocations with concomitant fractures of the radial head and the coronoid process) is controversial. Replacement appears to have advantages over repair in this setting, but further study is desirable.[13, 14]

Operative details

Adequate preoperative planning is essential. If replacement is a possibility on the basis of imaging studies demonstrating excessive comminution with distal radioulnar joint instability, then the surgeon needs to be sure that an adequate stock of radial head replacement implants is available. Similarly, a wide range of minifragment plates and screws should be available to accomplish fixation.

The radial head is approached posteriorly. The surgeon must be aware of the posterior interosseous nerve, which winds around the neck of the radius and lies directly on the bone. During the approach (and throughout the procedure), the surgeon should attempt to use indirect reduction techniques, preserving soft-tissue attachments. Periosteal stripping must be minimized. Narrow retractors are used, and the surgeon must avoid penetrating the interosseous membrane to avoid the complication of synostosis, which can cause severe limitation of motion that is difficult or impossible to treat (see Complications).

For isolated radial head dislocations, reduction of the head is usually stable, and no specific repair is necessary. If it is unstable, the annular ligament is repaired (if instability is still present, the surgeon should look for a missed forearm fracture).

Once the fracture is opened, the final decision is made regarding whether to carry out fixation, replacement, or excision. When possible, the best results are obtained with anatomic reduction and fixation. As with any surgical fracture treatment, if fixation is chosen, the first step is reduction of the bone fragments. The surgeon reduces and provisionally fixes the intra-articular fragments first, then attaches the construct to the shaft. In some cases, the radial head is removed and assembled on the back table, but if possible, fixing the fracture in place is preferable to preserve the blood supply provided through the remaining soft-tissue attachments.

Fixation options include minifragment plates and screws and Herbert screws.[15] Usually, 2.7-mm implants are used with interfragmentary lag screw fixation of individual fragments. Bone graft is included if the bone is significantly comminuted or if bone loss is preventing stable fixation. If more than 33% of the cortical circumference is lost, interfragmentary compression becomes impossible. Examples of radial head fracture fixation in an adult are presented in the series of five images below.

Children require anatomic reduction with the same indications as adults, but additionally, the surgeon must be aware of potential growth plate injury and late deformity. Treatment of a radial head fracture in a child is illustrated in the two images below.

If repair is not possible, excision of comminuted radial head fragments can be considered. The surgeon must test for valgus instability and, if necessary, repair the medial collateral ligament to restore stability if excision is chosen. If instability persists, replacement with a radial head spacer is the appropriate treatment instead of excision alone (see the images below). The surgeon must also be aware of the Essex-Lopresti lesion (ipsilateral injury to the distal radioulnar joint) and repair or fixate the distal radioulnar joint as necessary.

When radial head excision is chosen, the surgeon must not excise distal to the annular ligament, because this results in an unstable proximal radioulnar joint (see the images below).

If comminution extends distal to the annular ligament, then replacement with a spacer should be strongly considered (see the image below). Silicone was the standard material for the spacers, but manufacturers subsequently moved to titanium. The silicone implants were easier to place because of their flexibility, but concerns over silicone synovitis, late fragmentation, and loosening led to the development of the metal implants.[9, 16]

For Monteggia fracture-dislocations, best treatment includes ORIF of the ulna diaphyseal fracture. The ulna fracture is approached and reduced first. The radial head dislocation then usually reduces indirectly and is stable. (More than 90% of radial head dislocations are stable after fixation of the ulna.) If it is stable, then the radial head dislocation is treated closed. An irreducible radial head usually occurs because the diaphyseal ulna fracture has been poorly reduced, and this should be reassessed carefully, both radiographically and clinically. If it is unstable or irreducible (and the ulna is anatomic), then open reduction of the joint is required. The annular ligament is repaired during the open reduction.

Failure of the radial head to reduce with the ulna reduction is usually due to interposed annular ligament or, rarely, to interposed radial nerve. The image below shows a patient who presented after an unsuccessful attempt at open reduction of both components of the injury. If the radial head or neck is fractured and stable, then the choice of open versus closed treatment can be made as if the radial head injury were isolated, using the indications for open surgery as described above.

If the radial head or neck is fractured and unstable, it is approached and dealt with by means of an open surgical approach as described above (see the images below).

Elbow fracture-dislocations are usually due to more violent trauma and are usually unstable after reduction. ORIF is required. All efforts should be made to salvage the radial head because it is a secondary stabilizer of the elbow. The goal is stable fixation for early motion.

The wound can usually be closed, or skin grafts may be used for open wounds within 3-5 days.

Early complications of radial head or neck fractures or dislocations include the following:

• Compartment syndrome
• Neurovascular injury
• Infection

Late complications include the following:

• Nonunion
• Hardware failure
• Malunion
• Infection
• Synostosis
• Persistent pain

Compartment syndrome after isolated radial head fracture is unlikely but could occur with Monteggia fractures, floating elbow injuries, and associated crush injuries to the forearm. Compartment syndromes usually occur in high-energy trauma but can occur with prolonged low-energy injuries and gunshot injuries. Predisposing factors include vascular injury, coagulopathy, and limb compression. Prevent iatrogenic compartment syndrome during surgery by obtaining good hemostasis and by not closing the fascia at surgery.

Early diagnosis is necessary. The treating physician needs to have a high index of suspicion, remembering the standard signs and symptoms of increased compartment pressure: pain on passive stretch, palpable firmness or tightness of the compartment, altered sensation or paresthesias, pain out of proportion to that expected, pallor, pulselessness, and less than 30 mm Hg difference between compartment pressure and diastolic pressure. All affected compartments should be released.

Neurovascular injury after radial head fracture or dislocation is not common but occurs more often if the fracture is open. Iatrogenic injury is more frequent. The surgeon needs to remember the location of the posterior interosseous nerve as it travels along the neck of the radius. If no recovery occurs, the nerve usually is explored at 3 months.

Infection after radial head fracture can occur either early or late. Treatment requires irrigation and debridement and appropriate antibiotics (usually administered intravenously). If the fracture is healed or the hardware is loose, the hardware should be removed. If the fracture has not healed and the hardware is stable, the hardware is maintained.

Persistent pain after radial head fracture may be due to the hardware, intra-articular cartilage injury and posttraumatic arthritis, adhesions, malalignment, or associated nerve or muscle injuries. Hardware removal may be helpful, but potential complications, including iatrogenic nerve injury when dissecting through scar, may outweigh the benefits. Persistent pain may be due to nonunion. The images below show a patient who had persistent painful clicking after his radial head fixation, which resolved after hardware removal.

Nonunion and resultant hardware failure after radial head fracture are usually due to poor biomechanics. Poor biology is the result of poor initial fracture characteristics and damage to the soft tissue envelope. An open injury or an extensive surgical reconstruction with periosteal stripping predisposes to slow healing. Poor surgical technique with overaggressive iatrogenic damage to soft tissues is a contributing factor. Poor mechanics occurs when the surgeon is unable to obtain a stable construct. (This occurs with too few screws or failure to obtain interfragmentary compression.)

Treatment of nonunion requires restoration of normal biomechanics with stable internal fixation or radial head excision or replacement, depending on the fracture and wrist and elbow stability.

One study postoperatively evaluated 13 patients who had undergone radial head resection. Using physical examination findings, the Disabilities of the Arm, Shoulder, and Hand [DASH] questionnaire, Mayo Elbow Performance Score [MEPS], and the pain Visual Analog Scales [VAS] questionnaire, the results found that 72 months after surgery, the proximal radial stump had significant migration both medially and posteriorly compared with the opposite side. Radial head resection often leads to posterior and medial drift of the proximal radial stump, resulting in nonanatomic alignment with the capitellum; proximal radius resection length of greater than 2 cm was associated with larger amounts of drifting.[17]

Stiffness is common after elbow injuries, especially if they have been immobilized. Motion is difficult to recover even with extensive physical therapy, dynamic bracing, manipulation, or open release of adhesions. Avoiding the problem by early motion is preferable to trying to deal with it after contracture has already occurred.

Synostosis after radial head fracture or dislocation can be a disabling complication because it limits motion, especially rotation of the forearm. Risks include closed head injury, surgical delay longer than 2 weeks, and penetration of the interosseous membrane by bone graft or screws, bone fragments, or surgical instruments.

Treatment by resection with an interposition spacer restores motion in about 50% of patients. Generally, the surgeon should wait at least a year or until the bone is metabolically inactive on bone scanning. Surgery should generally be completed before 3 years. The first image below shows an example of a patient who developed synostosis. The second image below shows the synostosis. The synostosis was resected, and an interposition fat spacer was used with early motion. Significantly increased motion was obtained and maintained, as seen in the third image below.

Rehabilitation with range-of-motion exercises is begun as soon as the wound is healed, depending on the type of fracture and stability of fixation. The typical time to union is 6-8 weeks. Casting with the elbow in 90° of flexion is rarely needed to maintain the radial head reduction, but if the radial head is unstable, the surgeon needs to search for other causes, such as interposed annular ligament or osteochondral fragment or poorly reduced fracture.