Floating Elbow


Background

Floating elbow is an injury pattern involving a fracture of the humerus and a fracture of the radius and/or the ulna in the same extremity. This injury may be associated with an elbow dislocation in patients who sustain high-energy injuries (see the image below). The location of the fracture may dictate the treatment options. Regardless of where the fracture occurs, if the elbow remains dissociated from the hand and shoulder, the fracture is deemed to be floating.

Lateral radiograph of concomitant ipsilateral midsLateral radiograph of concomitant ipsilateral midshaft humerus and olecranon fractures.

The term floating elbow was first introduced by Stanitski and Micheli to describe an injury pattern in children involving concomitant fractures of the forearm axis and supracondylar humerus in the same extremity. [1 This description has been extended to adult patients who sustain ipsilateral fractures of the humerus and forearm. [2]

The spectrum of injury can vary greatly, depending on the force dissipated by the extremity and its position in space at the time of the incident. The nature of treatment of these injuries is dictated somewhat by the condition of the soft tissues and neurovascular bundle in the affected extremity and by other pending medical and surgical issues. As the orthopedic community has grown to understand how to best treat the isolated humerus and forearm fracture, this knowledge has been used to improve the outcome of these combined complex upper-extremity injuries. [345]

Anatomy

Osteology

The landmarks for the humerus include the greater and lesser tuberosities, the deltoid tubercle, and the epicondyles distally. Proximally, the surgical and anatomic neck can define the humerus. The shaft of the humerus has two distinct grooves: proximally between the two tuberosities for the biceps tendon and posteriorly in the midportion for the radial nerve.

As the shaft flares distally, the humerus broadens out into its medial and lateral epicondyles. These two epicondyles act as columns and support the trochlea of the distal humerus. The lateral column includes the epicondyle and ends in the radial articulation of the capitellum. The spool-like trochlea is suspended between the two epicondyles and lies in 4-8° of valgus and internal rotation with respect to the humeral shaft. The rotational axis of the capitellum lies 12-15 mm anterior to the anterior humeral line, in line with the axis of rotation of the trochlea. [67]

A thin shell of bone separates the coronoid and olecranon fossae just proximal to the trochlea. The olecranon is the flared proximal portion of the ulna. It articulates with the trochlea at its semilunar notch. The ulnar contribution to the proximal radioulnar joint lies just lateral to the coronoid process, the radial notch. The proximal radius is composed of a concave disk-shaped radial head and a short narrow neck.

The ulnohumeral articulation is characterized as a hinge/ginglymus joint with 1º of freedom (flexion/extension). Its stability is enhanced by the congruence of the articular surfaces, as well as by the medial collateral and lateral ulnar collateral ligaments. The radiohumeral articulation functions as a pivot, allowing flexion, extension, and rotation. It is stabilized by the lateral collateral ligament and the annular ligament.

The forearm is composed of the radius and ulna. Just distal to the radial head, the bicipital tuberosity lies on the anteromedial surface of the radial neck. The radius has a bow with an anterolateral convexity. This configuration must be restored to allow normal rotation about the forearm axis. The distal radius flares at the metaphysis to form a broad articulation with the scaphoid and lunate, with the radial styloid at the lateral margin of the distal articular surface. The Lister tubercle is palpable on the dorsal surface of the distal radius and is palpable between the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), and extensor pollicis tendons.

The ulna is triangular. It narrows and terminates in the distal ulnar head and styloid.

Musculature

The brachial musculature can be divided into flexor and extensor compartments. The flexor muscles include the biceps, brachialis, and coracobrachialis. The extensor compartment consists of the triceps with its medial, lateral, and long heads. The medial epicondyle acts as the origin of the forearm flexor muscles: the flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), flexor digitorum superficialis (FDS), and palmaris longus (when present). The lateral epicondyle provides the origin for the extensor muscles (ECRL, ECRB, extensor carpi ulnaris [ECU], and extensor digiti minimi [EDM]) and the supinator and anconeus muscles.

The forearm is divided into the following three compartments:

  • Volar compartment - Pronator teres and quadratus, FCR and FCU, FDS and flexor digitorum profundus (FDP), and flexor pollicis longus [FPL] (with FDP and FPL considered by some to be a separate deep compartment)
  • Mobile wad - ECRL, ECRB, and brachioradialis
  • Dorsal compartment - Extensor digitorum, EDM, ECU, abductor pollicis longus (APL), extensor pollicis brevis (EPB), extensor pollicis longus (EPL), and extensor indicis

Vascular

The axillary artery becomes the brachial artery as it passes underneath the pectoralis minor tendon. It then runs medially with the median nerve underneath the biceps brachii muscle. The profunda brachii branches at the junction of the proximal third and midthird of the humerus to run posteriorly with the radial nerve to supply the posterior compartment. The brachial artery runs down the arm, lying deep to the bicipital aponeurosis, anterior to the brachialis, and medial to the biceps tendon.

The brachial artery, as well as the profunda, gives off a rich anastomotic network of vessels around the elbow as it moves toward the fossa. Here, it bifurcates into the radial and ulnar arteries. The radial artery crosses deep to the aponeurosis and superficial to the pronator teres and then continues deep to the brachioradialis between the artery and the FCR to the wrist. The radial recurrent is a branch from the radial artery that lies anterior to the lateral humeral condyle to anastomose with the radial collateral branch from the profunda brachii artery.

The ulnar artery passes deep to the pronator teres and lies between the FDS and FDP proximally. Distally, it lies on the FDS between the FDP and the FCU. It gives off anterior and posterior recurrent arteries that surround the lateral epicondyle. The common interosseous artery branches from the ulnar artery in the proximal forearm; it immediately branches to form anterior and posterior interosseous arteries. The anterior component passes through the interosseous membrane near the wrist again to join its posterior component.

Nerves

The musculocutaneous nerve comes from the lateral cord of the brachial plexus. It pierces the coracobrachialis 5-8 cm distal to the tip of the coracoid and branches to supply this muscle, the biceps brachii, and the brachialis. The continuation of this nerve distally serves sensory function as the lateral antebrachial cutaneous nerve.

The radial nerve comes from the posterior cord of the plexus. It enters the posterior compartment through the triangular space between the long head of the triceps and the humerus. It spirals around the humerus from medial to lateral while supplying the triceps muscle. It then pierces the intermuscular septum and emerges between the brachialis and brachioradialis, passing anterior to the lateral epicondyle.

After supplying the anconeus and mobile wad, the radial nerve branches beneath the proximal part of brachioradialis into its two terminal branches, the superficial radial nerve and the posterior interosseous nerve (PIN). The PIN passes under the supinator and eventually lies immediately dorsal to the interosseous membrane. It supplies the remainder of the extensor muscles in the forearm. The superficial radial nerve runs deep to the brachioradialis in the forearm and provides cutaneous sensation to the dorsum of the hand after exiting the forearm between the ECRL and the brachioradialis.

The median nerve arises from the medial and lateral cords of the brachial plexus. It accompanies the brachial artery along the upper extremity. It does not supply any muscles or sensation in the brachium but does provide some fibers to the elbow joint. It passes through the antecubital fossa anterior to the medial epicondyle and deep to the bicipital aponeurosis, lying medial to the brachial artery in most of the population.

The median nerve exits the fossa medial to the brachial artery and continues into the forearm, splitting the two heads of the pronator teres. It runs between the FDS and the FDP, supplying all of the superficial flexors of the forearm except the FCU. The anterior interosseous nerve is given off as the median nerve splits the pronator teres. It supplies the deep flexors of the forearm except for the ulnar half of the FDP, specifically the FPL and pronator anadratus.

The ulnar nerve is the continuation of the medial cord of the plexus and stays medial to the brachial artery. This courses posterior to the medial epicondyle in its own groove. It provides no motor function in the brachium but does supply some fibers to the elbow joint. It enters the forearm between the two heads of the FCU, running distally between the FCU and the FDP. It innervates the FCU and the ulnar half of the FDP before entering the hand through the Guyon canal.

Etiology

The likely mechanism of injury in children who sustain an injury to the distal forearm axis and supracondylar humerus is a fall on the outstretched arm with the forearm pronated and the wrist hyperextended. [891011Direct trauma and other positions of the arm and forearm in space after falls also can cause similar constellations of injuries. In adult patients, the usual mechanism is direct high-velocity trauma (eg, from sideswipe injuries, crush-type injuries, or falls from extreme heights). [212]

Epidemiology

Fractures of the humerus associated with fractures of the forearm are rare, both in adults and in children. Most of these injuries in adults are the result of high-energy injuries. [13The literature has only a handful of reports describing the injury and results of treatment. In children, the incidence is better known, cited at 2-13% for concomitant fractures of the forearm axis and supracondylar humerus. [89101114]

Prognosis

The functional outcomes of these injuries vary in children and adult patients. Pediatric injuries historically have had better results than those of their adult counterparts, largely because of children's ability to remodel skeletal deformity with time.

In Stanitski's series of six patients, [1 all had an excellent outcome with respect to range of motion and carrying angle. Papavasiliou reviewed 24 cases and found similar results using the same treatment principles. [10 Templeton studied eight subjects with similar clinical presentation and found that seven had good or excellent results and one had a poor result (cubitus varus with limited but functional supination/pronation). [11]

Yokoyama et al reviewed a series of floating elbow injuries in adults. [2 Surgical management varied from case to case, but each fracture was managed with some type of operative intervention. All patients underwent standardized elbow evaluations, and a review of pertinent complications was included. They had 67% good or excellent results; the final elbow score did not correlate with timing of operation, concomitant neurovascular injury, or open fracture. Nonunions were present in four cases. All of these were fractures treated with unlocked intramedullary fixation.

Pierce and Hodorski reviewed 21 cases and found that only had 28% good results, with residual neurologic dysfunction in more than 50% of their patients. Lange reported on their experience with seven patients, with three good, one fair, and three poor results. [15 As advances in fracture fixation and understanding of the basic science of fracture healing have improved with time, so have the results of these devastating injuries.

In 2013, Ditsios et al [16described a prognostic classification for adults with the floating elbow injury. This classification system focuses on the presence or absence of intra-articular elbow involvement associated with the fracture pattern (see the image below), as follows: 

  • Group/type I - Humeral shaft fracture + radius and/or ulna shaft fracture 
  • Group/type IIa - Humeral shaft fracture + intra-articular radial head and/or olecranon fracture 
  • Group/type IIb - Intra-articular distal humerus fracture + radius and/or ulna shaft fracture 
  • Group/type III - Intra-articular distal humerus fracture + intra-articular radial head and/or olecranon fracture 
Ditsios floating elbow prognostic classification.Ditsios floating elbow prognostic classification.

They observed statistically poorer functional outcomes in fractures with intra-articular involvement, whether of the proximal forearm, the distal humerus, or both. Additionally, concomitant neurologic injury [1716 and nonoperative management [218have been found to predict statistically worse functional outcomes in multiple studies.


History

Patients with a floating elbow report pain and have an obvious deformity in the affected extremity. In both adults and children, the occurrence of neurovascular deficit is in the range of 25-45%. Other soft-tissue and associated injuries (eg, open fractures, closed head injuries [CHIs], and thoracoabdominal trauma) depend on the mechanism of injury and the severity of the pathology.

Physical Examination

A thorough physical examination is the benchmark of the initial patient evaluation. Careful documentation of the neurovascular status of the injured limb is crucial. Patients with a persistent pulseless extremity despite fracture reduction should undergo arteriography to rule out vascular injury if a delay in operative intervention is anticipated. Evaluation of soft-tissue viability is important in patients who sustain crush injuries and open fractures. The development of compartment syndrome should be diligently determined and appropriately treated. [19 All fractures should be reduced and splinted as appropriate.


Imaging Studies

The minimum radiographic workup for a patient with an injured extremity should include radiographs in the anteroposterior (AP) and lateral planes. (See the image below.) Traction on the affected extremity helps define the fracture lines. When standard radiographs do not provide enough information, oblique radiographs should be obtained.

Lateral radiograph of concomitant ipsilateral midsLateral radiograph of concomitant ipsilateral midshaft humerus and olecranon fractures.

Patients with a persistent pulseless extremity despite fracture reduction should undergo arteriography to rule out vascular injury if a delay in operative intervention is anticipated.



Approach Considerations

Indications for treatment of isolated humerus and forearm fractures vary greatly with patient age, location of the fracture, and injury to the soft-tissue envelope. [2021However, the rules change when these fractures occur concomitantly in the same extremity. Reports are few in adults, but available data suggest that patients with multiple fractures in the same upper extremity fare better with anatomic reduction and some type of definitive fixation both for humerus and for forearm fractures.

In children, reduction with percutaneous pinning is the standard of care for the supracondylar humerus fracture component, and management of the forearm component has been shown to be managed successfully either with closed or percutaneous techniques with similar results. Appropriate soft-tissue management is crucial to aid in fracture healing and may dictate the type of fixation used. [22231524182526]

Relatively few contraindications exist for fixation of fractures involved with this injury. Patients who sustain severe irreparable vascular compromise may need to undergo emergency amputation to facilitate patient resuscitation. Patients who are critically ill may require a delay in fixation to allow for recovery from the systemic inflammatory response that accompanies these injuries, but open reduction and internal fixation (ORIF) should still be undertaken when appropriate.

As methods of fracture care improve, especially in patients with multiple fractures, outcomes of these complex injuries should mirror those efforts. A wide multicenter review of these complex injuries would be helpful in further guiding the understanding of the pathology and treatment options in the floating elbow.

Nonoperative Therapy

Management of these complex injuries has evolved with the understanding of isolated upper-extremity fracture stabilization. Although the goals of therapy are the same, treatment guidelines for children and adults differ slightly. Regardless of age, initial management should include provisional immobilization of the fractures and appropriate debridement of open fracture wounds (see the image below). Administer intravenous (IV) antibiotics to patients with open fractures.

Initial management of Monteggia injury consisted oInitial management of Monteggia injury consisted of debridement and irrigation of extensively contaminated ulna fracture and application of external fixator for stability and reduction of radial head dislocation. Humeral fracture was splinted.

The vascular status of the limb must be assessed carefully. If a disruption is present or suspected, surgical consultation and coordination of management needs for the combined injury should take place.

Surgical Therapy

Neurologic deficit is a point of controversy, especially in those with a midshaft or distal-shaft humerus fracture. In deciding whether to explore a nerve that presents with a deficit, a number of factors should be taken into consideration, including the mechanism of injury, the location and characteristics of the fracture or fractures, the approach to surgical intervention, and the time when the deficit was discovered (before or after reduction).

The type of fracture management and soft-tissue coverage should be determined on a case-by-case basis. Some surgeons may elect to span the fractures with an external fixator until other patient care issues can be resolved. Others may elect to stage the procedures or fix both fracture complexes at once. All of these options are acceptable as long as the primary fracture principles are respected.

As noted, treatment guidelines for children [27 differ slightly from those for adults. Studies by Moed et al [24and Grace et al [22have shown that immediate internal fixation of both bone forearm fractures in adults with early range of motion (ROM) provides the patient with a stable construct that allows for accelerated rehabilitation and return to function.

Operative treatment of isolated humerus fractures in adults has its role in some instances, but for the most part, these injuries do well when treated in a closed manner with functional bracing. The combination of these injuries in the same extremity should be treated as a unit and not as separate entities. Rogers et al [18reviewed their series of floating elbows and found a high rate of humeral nonunion with closed treatment of the humeral fracture. Lange et al [15reviewed their experience with this injury and found that only patients who underwent operative management of the humeral fracture obtained a satisfactory result.

Operative management of the humeral component should consist of either rigid plate fixation (see the image below) or locked intramedullary nailing of the fracture. [28These techniques allow stable fixation of the fracture site and provide the best chance for union. Rigid fixation of these injuries allows for early ROM of all joints in the affected extremity. This facilitates rehabilitation of concomitant injuries.

Definitive management of fractures was performed wDefinitive management of fractures was performed with plate fixation.

In children, supracondylar humerus fractures should be treated with closed (or open, if necessary) reduction and percutaneous pinning. Little controversy exists about this component of the floating elbow. This option has provided the patient with the best opportunity for union of the distal humerus fracture without significant deformity. In children, acceptable results have been achieved with closed reduction of the forearm fracture, with or without percutaneous pinning.

The treating surgeon should base the treatment decision on the stability of the fracture reduction and the likelihood of achieving union without angulation. The opportunity for skeletal remodeling also factors into this decision, as well as the type of fixation required. Rehabilitation should be tailored to the individual injury pattern, with advancement of activity as fracture union progresses and muscle function returns. [2917]

Complications

Complications of treatment for floating elbow mirror those of treatment for other complex fractures. Significant neurovascular injury may accompany these injuries, ranging from simple isolated nerve palsy to complex brachial plexus lesions with axillary or brachial artery injury or disruption. [3016The cumulative incidence of some type of associated neurovascular injury in children and adults is 25-45%. Loss of ROM in the elbow and forearm axis is not uncommon, even with anatomic restoration of all fractures.

Infection is a notable complication, especially in those who sustain open fractures and require debridement and immediate internal fixation. It may be wise to delay definitive fixation until the soft tissues are in a condition in which appropriate skeletal management can be defined. Malunion and nonunion can result from a number of factors, including persistent infection, inadequate fixation, poor soft-tissue envelope, and poor technique.

Attention to proper surgical methods and an understanding of the severity of the injury assist the treating surgeon in minimizing these occurrences.


0 comments:

Post a Comment