Middle-Third Forearm Fractures 

Updated: May 31, 2019
Author: David A Forsh, MD; Chief Editor: Harris Gellman, MD 

Overview

Practice Essentials

The forearm plays an important role in flexion and extension of the elbow and wrist, as well as pronation and supination. Forearm fractures of the radius and ulna can be described according to their location, pattern, displacement, and associated soft-tissue injury. No single classification takes all of these variables into account, but in most instances, forearm fractures can be classified according to location (proximal third, midde third, or distal third). (See also Forearm Fractures, Distal-Third Forearm Fractures, and Forearm Fractures in Emergency Medicine, as well as Galeazzi Fracture and Monteggia Fracture.)

Unlike middle-third forearm fractures in infants and children, these fractrures in adults are unstable and result in significant dysfunction if treated inadequately. Nonanatomic alignment of the radial or the ulnar shaft can significantly impede forearm rotation. Therefore, nonunions and malunions of forearm fractures are functionally as well as cosmetically limiting.[1]

The independent but coordinated function of the wrist, forearm, and elbow is necessary to position and orient the hand in space. Injury to any of these components can result in significant functional deficit. Therefore, the main goal of treatment of middle-third forearm fractures is to restore anatomic length, alignment, and rotation in order to recover painless range of motion (ROM) of the elbow, forearm, and wrist. Adults with middle-third forearm fractures are typically treated surgically with open reduction and internal fixation  (ORIF).

For patient education resources, see the First Aid and Injuries Center, as well as Broken Arm.

Anatomy

The forearm has a complex anatomy. From an osseous standpoint, the forearm is made up of the radius, the ulna, and the interosseous membrane.

The radius is composed of the radial head, the radial neck, and the biceps tuberosity proximally. The radial shaft extends distal to the biceps tuberosity and is located on the lateral aspect of the forearm when it is supinated. The radial shaft has a radial bow that extends from the bicipital tuberosity to the ulnar aspect of the distal radius at the wrist. Distally, the radius articulates with the carpal bones in the wrist.

The ulna serves as the axis around which the radius rotates during pronation and supination. Proximally, the ulna is composed of the olecranon and the coronoid, which articulate with the distal humerus at the elbow. The ulnar shaft is located on the medial aspect of the forearm. Distally, the ulnar shaft broadens to form the ulnar head and the styloid process.

The space between the radius and the ulna is primarily occupied by the interosseous membrane, which separates the anterior and posterior compartments of the forearm.

Etiology

The majority of middle-third forearm fractures occur from high-energy trauma (eg, motor vehicle accidents [MVAs] or sports injuries). Direct injury to the forearm can result from gunshot injuries or from blunt trauma to the forearm. Indirect injury to the forearm can also occur from either bending or torsional forces.

Epidemiology

The average annual incidence of forearm shaft fractures has been reported to be 1.35 per 10,000 population, with a range of 0-4 per 10,000 population, depending on age and gender.[30]  Such fractures are relatively uncommon, compared with fractures of the humeral shaft, femur, and tibia. Forearm fractures predominantly occur in males, and the vast majority occur during the first four decades of life.[30] More than half of all forearm shaft fractures occur in males between the ages of 15 and 39 years.[30]  

 

Presentation

History

Middle-third forearm fractures may result from a lower-energy injury (eg, a ground-level fall or a fall onto an outstretched hand), from a direct blow, or from a higher-energy injury (eg, a fall from a height or a motor vehicle accident [MVA]). The mechanism of injury typically involves an axial load that is applied to the forearm through the hand.[32] The patient will complain of forearm pain and swelling, as well as visible deformity if there is displacement of the fracture. It is also important to assess for neurologic injury, as well as associated injuries in the ipsilateral extremity or elsewhere.

Physical Examination

On physical examination, the forearm will be swollen and may show gross deformity in cases where the fracture is displaced. There will be tenderness over the area of the fracture, and in cases without deformity, this should raise suspicion of a nondisplaced fracture. A careful inspection of the skin should be performed to rule out any open wounds. When open wounds are present, they most commonly occur on the ulnar side of the forearm.

In patients with middle-third forearm fractures, thorough neurologic and vascular examination of the ipsilateral extremity should be performed to evaluate for any peripheral nerve or vascular injuries, as well as associated injuries, particularly at the elbow and wrist. It is also important to evaluate for signs and symptoms of acute compartment syndrome in the forearm, especially after higher-energy injuries (though this can occur after lower-energy injuries as well).

 

Workup

Imaging Studies

Middle-third forearm fractures are routinely diagnosed with standard anteroposterior (AP) and lateral radiographs of the forearm. Radiographs must visualize the entirety of the forearm, including both the elbow and the wrist. (See the images below.) Dedicated radiographs of the elbow and wrist should also be performed to evaluate for associated injuries to these joints. This is particularly important for ruling out Galeazzi and Monteggia fracture-dislocations in the setting of isolated fractures of the radius or the ulna, respectively. In some instances, additional oblique views of the forearm may be helpful to better assess fracture pattern when there is overlap of the radius and ulna on the standard lateral view.

Anteroposterior radiograph of displaced midshaft b Anteroposterior radiograph of displaced midshaft both-bone forearm fracture in adolescent with transitional growth plate. This fracture should be treated as adult injury.
Anteroposterior radiograph of open middle-third fr Anteroposterior radiograph of open middle-third fracture of radius and ulna. Joints above and below fracture are visible.
Lateral radiograph of displaced midshaft both-bone Lateral radiograph of displaced midshaft both-bone forearm fracture in adolescent. Note that alignment in this view appears to be adequate; however, radius is short.
Lateral radiograph of open middle-third fracture o Lateral radiograph of open middle-third fracture of radius and ulna. Note proximity of bones to soft tissue.
Middle-third forearm fracture. Middle-third forearm fracture.
Middle-third forearm fracture. Middle-third forearm fracture.

On radiographs, the position of the bicipital tuberosity on the proximal radius can help in assessing the degree of pronation or supination of the proximal fracture fragment.

Computed tomography (CT) and magnetic resonance imaging (MRI) are rarely required for the assessment of acute forearm fractures. Advanced imaging is reserved for instances of middle-third forearm fractures involving pathologic lesions or unusually long fractures that extend into the wrist or elbow joint.[32]

 

Treatment

Approach Considerations

Middle-third forearm fractures are distinct from related injuries such as Galeazzi and Monteggia fractures, in that the wrist and elbow joints are not necessarily disrupted. Nevertheless, the interosseous space between the radius and the ulna can be thought of as an articulation that allows rotation of the radius around the ulna.

The main goal of treatment for middle-third forearm fractures is to restore anatomic length, alignment, and rotation in order to regain painless function and range of motion (ROM) of the forearm, elbow, and wrist. As with most fractures, treatment of middle-third forearm fractures should follow three basic principles:

  • Obtaining an adequate fracture reduction
  • Maintaining the reduction while preserving the biology
  • Allowing early ROM

In view of the unique geometric relation between the radius and the ulna that allows for forearm pronation and supination, there is little room for residual deformity, and anatomic reduction is required.[31]  

Provisional management of middle-third forearm fractures involves temporary stabilization with an above-elbow splint. Patients with open wounds should receive intravenous (IV) antibiotics and, if necessary, tetanus prophylaxis (depending on their immunization history). Provisional management of middle-third forearm fractures with open wounds should include irrigation and coverage of the wounds with a sterile dressing, followed by early surgical irrigation and debridement. 

In adults, true nondisplaced middle-third both-bone forearm fractures are rare. When they do occur, they can be treated nonoperatively in a long arm cast for 6-12 weeks with close monitoring for fracture displacement. Weekly radiographic follow-up is initially required to assess for interval fracture displacement that may necessitate conversion to surgical treatment. No studies to date have compared outcomes between nonsurgical and surgical treatment of nondisplaced both-bone forearm fractures.

Additionally, isolated nondisplaced ulnar-shaft fractures or minimally displaced fractures of the distal two thirds of the ulnar shaft with less than 50% displacement and less than 10º of angulation may be treated nonoperatively. 

Middle-third forearm fractures with even minimal displacement are prone to subsequent displacement, malunion, or nonunion.[31, 32] A cadaveric study of both-bone forearm fractures showed that 10º of angulation did not significantly affect forearm rotation, but an increase to 20º of angulation resulted in a significant and functionally important loss of forearm rotation.[33] In view of the significant degree of functional loss from minimal fracture displacement, middle-third both-bone forearm fractures are typically treated surgically with open reduction and internal fixation (ORIF).

Surgical Therapy

Operative treatment of middle-third forearm fractures is the rule rather than the exception. The purpose of surgical treatment is to achieve anatomic reduction and stable fixation and thereby allow early ROM. Careful management of soft tissues is also essential in order to minimize disruption of the blood supply to the bone and optimize bone healing.

ORIF with plates and screws is the most widely used method for the treatment of middle-third forearm fractures. Historically, intramedullary nailing of the forearm was performed with solid nails. However, anatomic reduction was difficult to achieve with these solid nails, and little rotational stability was provided. Accordingly, intramedullary nailing of forearm fractures was found to have less favorable results. However, there has been increased interest in intramedullary nailing using interlocking nails because this technique results in minimal soft-tissue disruption.

ORIF with plates and screws is considered the gold standard in the surgical treatment of middle-third forearm fractures.[34] Open reduction with exposure of the fracture allows the removal of any soft tissue that may be interposed in the fracture site, as well as direct visualization of anatomic fracture reduction. Fixation with plates and screws provides rigid stability that allows early ROM postoperatively.

The location of the fracture will determine the type of surgical approach that is needed to fix the radius. Typically, fractures of the distal half of the radius may be fixed through a volar Henry approach, whereas fractures of the proximal half of the radius may be treated through a dorsal Thompson approach. In contrast to the radius, the ulna is almost universally exposed through an ulnar approach between the extensor carpi ulnaris (ECU) and the flexor carpi ulnaris (FCU).

Once the fractures are adequately exposed, anatomic reduction is achieved, and fixation is performed with 3.5-mm compression plates and lag screws, if necessary. Plate positioning depends on the surgical approach and can be either volar or dorsal. Dorsal positioning of plates on the forearm is biomechanically superior, but volar placement of plates on the radius and ulna may allow better seating of the plates, as well as better soft-tissue coverage.[31, 32] (See the images below.)

Anteroposterior radiograph of completed open reduc Anteroposterior radiograph of completed open reduction and internal fixation (ORIF) of middle-third forearm fracture.
Anteroposterior radiograph of completed fixation o Anteroposterior radiograph of completed fixation of middle-third forearm fracture.
Lateral radiograph of completed open reduction and Lateral radiograph of completed open reduction and internal fixation (ORIF) of middle-third forearm fracture.

With respect to biomechanics, it is generally recommended that screws should engage at least six cortices on each side of the fracture. That is, fixation should include at least three bicortical screws on each side of the radial-shaft fracture and three bicortical screws on each side of the ulnar-shaft fracture in order to obtain stable fixation.

Healing rates for both-bone forearm fractures treated by means of open reduction with plate and screw fixation are excellent. A 1965 study by Sargent et al reported a 100% healing rate in a series of 29 patients with forearm-shaft fractures treated with open reduction and double plating.[35] Similarly, a 1975 study by Anderson et al, which included a larger cohort of 330 diaphyseal forearm fractures treated with compression plating, cited healing rates of 98% for radial-shaft fractures and 96% for ulnar shaft fractures.[36]  In 1989, Chapman et al reported a 98% healing rate for 129 forearm-shaft fractures treated with compression plates and screws.[42]

The excellent healing rates demonstrated in these early studies have consistently been reproduced in multiple subsequent studies.[37, 38, 39, 40, 41]

Intramedullary nailing of forearm-shaft fractures was first described over a century ago. Intramedullary fixation of both-bone forearm fractures has several theoretical advantages, including the following[51] :

  • Smaller incisions
  • No periosteal stripping
  • Lower risk of repeat fracture
  • Load-sharing in comminuted fractures

Historically, solid nails were used, and issues with nail entrapment, fracture distraction, rotational instability, and prolonged cast immobilization to maintain reduction were noted.[44] Currently available implants for intramedullary nailing of forearm-shaft fractures now allow locking of the nail to the bone segment adjacent to the nail's entry portal. Radial nails are inserted between the extensor tendons near Lister's tubercle, and ulnar nails are inserted through the posterior olecranon.

Despite the theoretical improvement in rotational stability when interlocking intramedullary nails arfe used, postoperative immobilization is still required until there is radiographic evidence of callus formation (commonly ~6 weeks).[45] Additionally, intramedullary nails do not provide compression and thus do not allow for primary bone healing. This may make it difficult or impossible to restore anatomic forearm geometry, including radial bow and rotational alignment. Therefore, the benefits of using a minimally invasive approach must be weighed against the risks of prolonged postoperative immobilization, as well as difficulties with achieving anatomic reduction and primary bone healing.

Hybrid fixation of both-bone forearm fractures using intramedullary nailing of the ulna in combination with ORIF of the radius has also been described, with reported outcomes comparable to those of ORIF of both the radius and the ulna.[37]

Studies examining outcomes following intramedullary nailing of forearm-shaft fractures have demonstrated good-to-excellent results. In a series of 38 forearm shaft fractures treated with interlocking intramedullary nails, Lee et al demonstrated good or excellent functional outcomes in 92% of patients.[46] In a larger series of 118 forearm fractures treated with interlocking intramedullary nailing, Visna et al reproted a 100% healing rate, with an average time to fracture union of 14 weeks.[47] Multiple other studies have found similarly high healing rates following intramedullary nail fixation of forearm-shaft fractures.[44, 48]

Postoperative Care

Patients who undergo operative fixation of forearm-shaft fractures are typically admitted overnight for close clinical monitoring for compartment syndrome. If pain is adequately controlled on postoperative day 1, patients may be discharged home with instructions to return to the emergency department (ED) if they begin experiencing signs or symptoms of compartment syndrome.

The operated arm should be elevated for 72 hours after surgery to reduce swelling and pain. No weightbearing is allowed on the operated arm after ORIF with plates and screws, but early ROM of the fingers, wrist, and elbow is encouraged to prevent stiffness. Early active pronation and supination have also been recommended and are typically initiated in the first to second postoperative week as the patient's comfort allows and as the need for soft-tissue rest permits. Functional outcomes after plate-and-screw fixation of both-bone forearm fractures have been shown to be significantly better with early ROM than with prolonged immobilization.[43]

Routine radiographs taken during follow-up are monitored to assess fracture healing radiographically. Once radiographic healing is visible (on average, 8-24 weeks after surgery), patients may gradually return to most activities. Athletic patients who participate in contact sports may require a brace may be required for as long as 6 months postoperatively.[32]

Complications

Complications of middle-third forearm fractures include infection, malnunion or nonunion, radioulnar synostosis, nerve palsy, re-fracture, and compartment syndrome.

The incidence of infection following operative treatment of foream shaft fractures has been reported to be between 0% and 3%.{ref 36-37} Signs and symptoms of infection include erythema, warmth, and swelling. While these signs are expected during the early postoperative period, increasing pain, fever, and purulent drainage should prompt suspicion for infection. When infection occurs, management can range from antibiotic treatment to hardware removal after fracture healing. Superficial infections can usually be treated with a 10-day course of oral antibiotics. In contrast, deep infections require multiple interventions including repeat operative irrigation and debridements, as well as possible hardware removal after fracture healing.

Malunion of middle-third forearm fractures may significantly limit forearm rotation. Furthermore, imbalance in forearm musculature due to malunion may potentially result in pain at the distal radioulnar joint and reduced grip strength.{ref 52} While large series by Anderson et al. and Chapman et al. did not specifically report on malunion rates, the overall excellent functional results suggests that symptomatic malunion is rare.{ref 36, ref 42} A cadaveric study has also suggested that malalignment of both-bone forearm fractures of up to 10 degrees does not cause significant functional limitations.{ref 33} When symptomatic malunion does occur, correction of the malaignment with osteotomies and revision plating may be performed after appropriate radiographic evaluation with standard radiographs, CT, and contralateral forearm radiographs.{ref 52}

Forearm fracture nonunions significantly delay functional recovery, which then leads to poor outcomes. {ref 36} Nonunion rates after open reduction with plate and screw fixation ranges from 0% to 10%.{ref 37, ref 38, ref 42} Nonunions are generally thought to be due to inadequate biomechanics (e.g., plate length, plate positioning, screw positioning) or inadequate biology (e.g., open fractures, fracture comminution, soft tissue injury, infection). Suspected nonunions of forearm shaft fractures should be closely monitored for 6 months in order to confirm that there is no radiographic progress in healing. Treatment for forearm fracture nonunions that are not infected typically involves revision open reduction and internal fixation, bone grafting, or a combination of both.

Radioulnar synostosis is a bony bridge between the radius and ulna. Postoperative radioulnar synostosis is rare with the use of a dual-incision approach, taking care to avoid placing bone graft in the interosseous space, and early range of motion.{ref 31} An estimated 1% to 6% of forearm fractures develop complete radioulnar synostosis.{ref 36, ref 49} In a series of 108 patients with forearm fractures, Hadden et al. found 6 patients with radioulnar synostosis, all of whom had a closed head injury.{ref 49} Similarly, Chapman et al. reported a single case of radioulnar synostosis in a patient with a closed head injury in a series of 88 forearm shaft fractures that were treated operatively.{ref 42} Risk factors for radioulnar synostosis are both-bone fractures that affect the radius and ulna at the same location on the forearm, significant fracture comminution, head injury, soft tissue trauma, and delayed surgery.{ref 31, ref 36, ref 53} 

Nerve injury may occur during operative treatment of forearm fractures. The most frequently injured nerve is the radial nerve or its terminal motor branch - the posterior interosseous nerve. When there is permanent nerve injury, treatment includes direct nerve repair and tendon transfers.

Hardware removal following plate and screw fixation of forearm fractures is not routinely recommended. Plate removal following surgical fixation of forearm shaft fractures occurs in less than 10% of cases.{ref 36} The subcutaneous location of ulnar plates make them more susceptible to persistent symptoms requiring implant removal. However, the benefits of plate removal should be weighed against several risks, including re-fracture, infection, and nerve injury. Re-fracture through either the original fracture site or through an empty screw hole has been reported to occur in as many as 18% of patients following implant removal.{ref 36} Hardware removal should be delayed until 12 to 18 months following surgery in order to decrease the risk of re-fracture.{ref 36} Additionally, the use of a splint or removeable brace for 4 to 6 weeks following implant removal has also been recommended.{ref 36} Lastly, it is important to note that re-fracture can also occur even without hardware removal. In these cases, re-fracture usually occurs through either the most proximal or the most distal screw hole.{ref 50}

The incidence of forearm compartment syndrome following open reduction and internal fixation of forearm fractures is 2%.{ref 39} Compartment syndrome can occur even after seemingly minor trauma. Overnight admission following surgical fixation of forearm fractures is therefore recommended to monitor for the development of this potentially devastating complication. Compartment syndrome is an orthopaedic emergency that requires emergent compartment release.