Forearm fractures are very common in young active adults. These fractures generally include at least one or both of the forearm bones namely radius or ulna.
Forearm has two bones radius and ulna. They articulate at elbow and wrist with each other and other bones to form part of elbow and wrist joints. Forearm fracture involves fracture of shaft of ulna or radius or both bones. On most of the occasions, both bone fracture together. In case of single bone fractures, the proximal or distal joint might be injured.
It is uncommon for a single bone to be injured without any associated injury to other bone or either joint.
The forearm is a complex anatomic structure and very important part of upper extremity.
Malunion [shortening and angulation] can cause many problems of function of upper limb.
Therefore, precise reduction for anatomical restoration and secure fixation is very necessary in forearm fractures.
Relevant Anatomy of Forearm Bones
The radius and ulna are two bones of the forearm and come into contact with each other only at the ends. They connect proximally at elbow joint and distally at radioulnar joint.
Ulna bone is relatively straight bone. It articulates with the distal humerus at the elbow, and runs virtually subcutaneously distally to the ulnar styloid at the wrist.
The other bone, the radius is bowed. Its articulation with capitellum of humerus angles at least 13° opposite to the bow.
Radial bow and interosseous space must be preserved for normal motion of forearm.
Mechanism of Injury of Forearm Fractures
Forearm fracture can be caused by various mechanisms. The most common is motor vehicle injury especially automobile and motorbike injuries. Most of these vehicular accidents result in some type of direct blow to the forearm.
Direct trauma by an object such as stick etc also can cause the fracture of these bones.
Gunshot wounds can cause forearm fracture. Such injuries are commonly associated with nerve or soft tissue deficits and frequently have significant bone loss.
Another cause is pathological forearm fracture and in such cases a previous underlying pathology is responsible for the injury. This injury can result from trivial trauma, a force which normally would not cause break in the normal bone.
Forearm fracture can occur as a result from fall too as in fall from heights.
Clinical Presentation of Forearm Fractures
In adults, it is very rare for these fractures to be undisplaced. As radius and ulna are strong bones, an injury of sufficient force is required to break them which would cause displacement.
After forearm fracture, the patient usually presents with history of significant trauma which results in pain, swelling, deformity and loss of associated function of the forearm. Often the displacement is significant enough to make a clinical diagnosis. Level of the deformity or level of tenderness in case of undisplaced fractures tells about the level of the fracture.
Presence of wound is likely to make the fracture open. Therefore any wound especially near the fracture site should be examined for communication with fracture hematoma. A careful neurologic evaluation of the motor and sensory functions of the radial, median, and ulnar nerves should be done. Amount Distal pulses should be palpated to check for vascular status of the forearm.
Swelling of the forearm should assessed to rule out compartment syndrome. A simple clinical test to diagnose a compartment syndrome is passive stretch of the fingers. If pain in the forearm is present when the fingers are passively extended, a compartment syndrome is probably present.
If the patient is noncooperative or unconscious, compartment pressures should be measured to rule out the possibility of compartment syndrome.
A simple anteroposterior and lateral radiograph of the forearm would help to diagnose the fracture pattern and the level of forearm fracture. Wrist and elbow joints should be included in the radiographs to rule out any associated injury.
The configuration of midshaft fractures of the radius and ulna varies depending on the mechanism of injury and the degree of violence involved.
Low-energy fractures tend to be transverse or short oblique, whereas high-energy injuries are comminuted or segmented and are often associated with extensive soft tissue injuries.
A line drawn through the radial shaft, neck, and head should pass through the center of the capitellum on any radiographic view of the elbow. This simple test can determine any associated elbow injury.
In case of doubtful wrist and elbow injuries computed axial tomography can be undertaken to look for subtle injuries. It is better to involve the normal part of the opposite limb for comparison.
Treatment of Forearm Fractures
Forearm fracture can be treated with various options. These vary from cast immobilization, plate fixation, intramedullary nailing to external fixation with each of them having an appropriate indication.
The basic principle behind the treatment is accurate anatomic reduction, rigid fixation, and early mobilization of the soft tissues.
Majority of displaced fractures of the shafts of the radius and ulna are treated by operative method. Closed treatment of forearm fracture should be undertaken only if there is a specific contraindication to operative treatment. Nondisplaced fractures of the shafts of both the radius and the ulna are very rare in adults.
Simple cast immobilization is used in undisplaced fracture of both bones of the forearm in adults. However this entity is very rare in adults.
Following cast application, x-rays should be done at weekly interval. It is very common for these fractures to become displaced later, therefore they should be watched. In case the displacement occurs, it should be treated as displaced fracture.
Displaced fractures of forearm do not yield satisfactory results with closed treatment and should be operated whenever possible.
Operative treatment allows for accurate fracture reduction and secure fixation.
To achieve excellent results, anatomical reduction and stable fixation are required. Restoration of normal bone length will prevent subluxation of either the proximal or distal radioulnar joint and will reestablish length to the muscles. Restoration of rotational alignment is essential for normal pronation–supination function of the forearm.
Open reduction and internal Fixation using plate fixation is the standard treatment for closed, displaced fractures of forearm. These fractures of both bones of the adult should be fixed as soon as feasible preferably within the first 24 to 48 hours of injury because the fractures lying in liquid hematoma are easier to reduce and fix.
But these fractures should be fixed any time irrespective of the delay for whatsoever reason.
Most of the fractures of both bones of forearm i.e. radius and ulna are treated by operative methods as non operative methods are not very successful especially in displaced fractures.
For closed fractures of these bones, the surgery is either fixation with plate and screws or intramedullary nailing.
Stainless steel, limited-contact, dynamic compression plate is the treatment of choice for displaced fractures of the radius and ulna and provide very good results.
The preferred plate is the eight-hole dynamic compression plate with 3.5-mm cortical screws.
Though plate and screw combination takes care of most of fracture configurations, there are some situations like open fractures, segmental fractures, failed plating and multiple injuries where nailing might be preferred.
Disadvantage of the plating is extensive soft tissue dissection and periosteal stripping. Advantage is ability of the surgeon to reduce and fix fractures in anatomical position.
Fixation with intramedullary nails is a poor implant as compared to plating and should be reserved for selected indications. Anatomical reduction is of paramount importance in these fractures and that is difficult to achieve with nails.
External fixators are used in case of open injuries or massive soft tissue loss.
Open forearm fractures require emergency treatment. The treatment needs to be individualized depending upon patient profile and wound.
Complications of Forearm Fracture
The complications associated with forearm fracture can be due to injury per se, failure to get right treatment or complication of treatment as such. Many complications are general complications associated with any fracture and few are specific to these fractures.
Here is a list of most common complications of these fractures.
- Nerve Injury
- Vascular Injury
- Compartment Syndrome
- Posttraumatic Radioulnar Synostosis
- Muscle and Tendon Entrapment and Adherence
- Soft Tissue Contracture
- Subluxation/dislocation of the distal radioulnar joint in Galeazzi fracture
- Radial head instability in Monteggia fracture dislocation
Special Forearm Injuries
Galeazzi Fracture is the fracture of radius bone associated with injury to distal radio ulnar joint. A fracture of the similar pattern involving ulna and proximal radio ulnar joint is called Monteggia Fracture. Galeazzi fracture is three times more common than Monteggia fracture.
Galeazzi fracture usually occurs due to either direct blows on the dorsolateral side of the wrist or fall on the hand. The most probable mechanism of injury in Galeazzi fracture is a fall on the outstretched hand combined with marked pronation of the forearm.
The xrays help to determine the level of the fracture, configuration of the fracture and associated distal radioulnar joint injury.
The injury to the radioulnar joint may be purely ligamentous, or the ulnar styloid may be avulsed. Except for undisplaced fractures, most fractures involving radius [and sparing ulna] have associated distal radioulnar joint pathology or damage to the interosseous membrane.
Treatment of Galeazzi Fracture
Though rare, undisplaced fracture of the shaft of the radius can be managed with above elbow cast immobilization. Patient should be followed up with x-rays every week to not for the displacement of the fracture. If it gets displaced it should be treated as displaced fracture.
Displaced fractures do not yield good results with closed reduction and plaster cast application. Open reduction and internal fixation using plate and screws is the preferred treatment. Distal radioulnar joint should be assessed after the fixation and if required can be given a temporary stabilization by K-wire.
Implant of choice for Galeazzi fracture is limited contact dynamic compression plate and 3.5 mm screws.
Using dorsal or volar approach, the radius fragments are exposed and reduced. The fracture is fixed with implant of suitable size usually 6 or 7 hole plates may be 5 holes in case one fragment is very small.
If the joint is reducible but unstable, then the position of maximum stability should be found and limb should be splinted in that position. The splint is continued for 4 weeks after the injury and the mobilization of the limb should begin. Night splinting in the stable position should continued until 3 months after injury.
If no stable position can be found, the distal radioulnar joint should be stabilized with a radioulnar pin for 3 weeks. Alternatively a screw can be used if greater stabilization is needed. The problem with screw is difficult removal.
Very rarely the joint may not be reducible at all. This usually happens in case of malreduction of the radius or soft tissue interposition within the joint.
If the reduction is anatomic and joint is not reducible, open reduction of the distal radioulnar joint is required.
Fracture of the ulna with associated dislocation of the radial head is termed as Monteggia fracture after the surgeon who described the injury in early 19th century.
These injuries are more common in children and exact incidence in adults is unknown.
Monteggia fracture most commonly occurs due to fall on outstretched hand.
The patient usually present with pain and swelling of the elbow and of upper third of forearm. Often the dislocated radial head can be palpated.
The affected limb should be carefully examined for any neurological deficit and vascular deficit. Radial nerve injuries are commonly associated with Monteggia fracture.
Any associated injury should be noted
In a Monteggia fracture, true anteroposterior and lateral x-rays of the elbow must be included in any upper extremity injury that involves a displaced fracture of the ulna.
Alignment of the radial head can be found by a simple test.
A line drawn down the shaft of the radius through the radial head should bisect the capitellum regardless of the position of the forearm.
If it does not, the radial head is subluxated or dislocated.
Classification of Monteggia Fracture
Classification of Monteggia fractures were given by Bado. Initially Bado described four types of this lesion.
|Type I Monteggia Fracture
Fracture of the ulnar diaphysis at any level with anterior angulation at the fracture site and an associated anterior dislocation of the radial head.
| Type II Monteggia Fracture
Fracture of the ulnar diaphysis with posterior angulation at the fracture site and a posterolateral dislocation of the radial head.
|Type III Monteggia Fracture
Fracture of the ulnar metaphysis with a lateral or anterolateral dislocation of the radial head.
|Type IV Monteggia Fracture
Fracture of the proximal third of the radius and ulna at the same level with an anterior dislocation of the radial head.
After Bado, four different subgroups of the posterior Monteggia fracture [type II] were suggested by Jupiter et al. These subgroupings were based on the location of the ulnar fracture.
The ulnar fracture involves the distal olecranon and coronoid process.
The ulnar fracture is at the metaphyseal and diaphyseal juncture, distal to the coronoid.
The ulnar fracture is diaphyseal.
The ulnar fracture extends along the proximal third to half of the ulna.
Bado type I is the most common type of Monteggia fracture(59%), followed by type III (26%), type II (5%), and type IV (1%). .
Treatment of Monteggia Fracture
Adult Monteggia fracture rarely yields to closed reduction. Most of the time operative treatment is needed. The goal is to fix ulna in anatomical position and reduce radial head. Ulna is usually fixed by a 3.5-mm limited-contact dynamic compression plate .
Monteggia fracture should be operated as soon as feasible. After stabilization of the ulna, the elbow is passively ranged to assess the stability of the radial head. An image intensifier can help assess radial head stability. After the surgery wound is closed in layers without closure of fascia.
If there is a radial or posterior interosseous nerve palsy that has occurred with injury, the course of action depends on reduction of radial head. if the reduction of radial head occurs easily, exploration of the radial or posterior interosseous is not indicated.
The kind of injury is usually a neuropraxia, and function returns within 6 to 12 weeks after injury in the most of the cases.
If the nerve does not recover within the expected period, exploration and repair of the nerve is indicated.
Extensive comminution of the ulna can present problems with regaining anatomic length of the ulna. If the radial head is reduced and is stable, this often facilitates reconstruction of the length of ulna so that it can be plated to its normal anatomic length.
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