HUMERAL SHAFT FRACTURES

EPIDEMIOLOGY

It is a common injury, representing 3% to 5% of all fractures.

Incidence is 14.5 per 100,000 per year.

Two percent to 10% are open fractures.

Sixty percent involve middle third, 30% involve proximal third, and 10% involve distal third of the diaphysis.

Bimodal age distribution with a peak in the third decade is seen in men and peak in the seventh/eighth decade is seen in women.

ANATOMY

Humeral shaft extends from the pectoralis major insertion to the supracondylar ridge. Cross-sectional shape of humeral shaft changes from cylindric proximally to a narrower triangular shape distally.

Vascular supply to the humeral diaphysis arises from perforating branches of the brachial artery, with the main nutrient artery entering the medial humerus distal to the midshaft (Fig. 16.1).

Musculotendinous attachments of the humerus result in characteristic fracture displacements (Table 16.1).

Radial nerve can be identified 14 to 15 cm proximal to the lateral epicondyle or 20 to 21 cm proximal to the medial epicondyle.

MECHANISM OF INJURY

Direct (most common): Direct trauma to the arm from a blow or motor vehicle accident results in a transverse or comminuted fracture.

Indirect: A fall on an outstretched arm results in spiral or oblique fractures, especially in the elderly. Throwing injuries with extreme muscular contraction and arm wrestling have also been reported to cause humeral shaft fractures.

Fracture pattern depends on the type of force applied:

• Compressive: proximal or distal humerus fractures

• Bending: transverse fractures of the humeral shaft

• Torsional: spiral fractures of the humeral shaft

• Torsional and bending: oblique fracture, often accompanied by a butterfly fragment

   

  CLINICAL EVALUATION

Patients with humeral shaft fractures typically present with pain, swelling, deformity, and shortening of the affected arm.

A careful neurovascular examination is essential, with particular attention to radial nerve function. In cases of extreme swelling, serial neurovascular examinations are indicated with possible measurement of compartment pressures.

Physical examination frequently reveals gross motion with crepitus on gentle manipulation.

Soft tissue abrasions and minor lacerations must be differentiated from open fractures.

Intra-articular extension of open fractures may be determined by intra-articular injection of saline distant from the wound site and noting extravasation of fluid from the wound.

RADIOGRAPHIC EVALUATION

Anteroposterior (AP) and lateral radiographs of the humerus should be obtained, including the shoulder and elbow joints. To obtain views at 90 degrees from each other, the patient, NOT the arm, should be rotated (transthoracic lateral), as manipulation of the injured extremity will typically result in distal fragment rotation only.

Traction radiographs may aid in fracture definition in cases of severely displaced or comminuted fractures.

Computed tomography, bone scans, and magnetic resonance imaging are rarely indicated except in cases in which pathologic fracture is suspected.

CLASSIFICATION

Descriptive

Open versus closed

Location: proximal third, middle third, distal third

Displacement: nondisplaced, displaced

Direction and character: transverse, oblique, spiral, segmental, comminuted

Intrinsic condition of bone: normal, osteopenic, pathologic

Articular extension

Orthopaedic Trauma Association Classification

See Fracture and Dislocation Compendium at http://ota.org/compendium/index.htm.

TREATMENT

Goals are fracture union with acceptable humeral alignment and patient return to preinjury level of function.

Both patient and fracture characteristics, including patient age and functional level, presence of associated injuries, soft tissue status, and fracture pattern, need to be considered when selecting an appropriate treatment option.

Nonoperative

Most humeral shaft fractures (>90%) will heal with nonsurgical management.

Nonoperative treatment requirements are:

• An understanding by the treating physician of the postural and muscular forces to be controlled

• Close patient supervision and follow-up

• A cooperative and preferably upright and mobile patient

• An acceptable fracture reduction

• Intact/innervated arm musculature (e.g., intact brachial plexus)

Twenty degrees of anterior (sagittal) angulation, 30 degrees of varus (coronal) angulation, and up to 3 cm of bayonet apposition are acceptable and will not compromise function or appearance.

Hanging cast: Utilizes dependency traction by the weight of the cast and arm to affect fracture reduction.

• Indications include displaced midshaft humeral fractures with shortening, particularly spiral or oblique patterns. Transverse or short oblique fractures represent relative contraindications because of the potential for distraction and healing complications.

• The patient must remain upright or semiupright at all times with the cast in a dependent position for effectiveness.

• It may be exchanged for functional bracing following early callus formation.

• More than 95% union is reported.

Coaptation splint: Utilizes dependency traction and hydrostatic pressure to effect fracture reduction but with greater stabilization and less distraction than a hanging arm cast. The forearm is suspended in a collar and cuff.

• It is indicated for the acute treatment of humeral shaft fractures with minimal shortening and for short oblique or transverse fracture patterns that may displace with a hanging arm cast.

• Disadvantages include irritation of the patient’s axilla and the potential for splint slippage.

• It is frequently exchanged for functional bracing 1 to 2 weeks after injury.

Thoracobrachial immobilization (Velpeau dressing): This is used only in elderly patients or children who are unable to tolerate other methods of treatment and in whom comfort is the primary concern.

• It is indicated for minimally displaced or nondisplaced fractures that do not require reduction.

• Passive shoulder pendulum exercises may be performed within 1 to 2 weeks after injury.

• It may be exchanged for functional bracing 1 to 2 weeks after injury.

Shoulder spica cast: This has limited application, because operative management is typically performed for the same indications.

• It is indicated when the fracture pattern necessitates significant abduction and external rotation of the upper extremity.

• Disadvantages include difficulty of cast application, cast weight and bulkiness, skin irritation,

  patient discomfort, and inconvenient upper extremity position.

Functional bracing: This utilizes hydrostatic soft tissue compression to effect and maintain fracture alignment while allowing motion of adjacent joints.

• It is typically applied 1 to 2 weeks after injury, after the patient has been placed in a hanging arm cast or coaptation splint and pain/swelling has subsided.

• It consists of an anterior and posterior (or medial–lateral) shell held together with Velcro

  straps.

• Success depends on an upright patient and brace tightening daily, as well as functioning upper arm musculature.

• Contraindications include massive soft tissue injury, an unreliable patient, and an inability to

  obtain or maintain acceptable fracture reduction.

• A collar and cuff may be used to support the forearm, but sling application may result in varus angulation.

• The functional brace is worn for a minimum of 8 weeks after fracture or until radiographic

  evidence of union.

  Operative

Indications for operative treatment include:

• Multiple trauma

• Inadequate closed reduction or unacceptable malunion

• Pathologic fracture

• Associated vascular injury

• “Floating elbow”

• Segmental fracture

• Intra-articular fracture extension

• Bilateral humeral fractures

• Open fracture

• Neurologic loss following penetrating trauma

• Brachial plexus injury

• Radial nerve palsy after fracture manipulation (controversial)

• Nonunion

• Unfavorable body habitus such as morbid obesity or pendulous breasts (relative indication)

• Chronic shoulder or elbow stiffness as it results in increased motion through the fracture and increases the risk on nonunion (relative indication)

Surgical approaches to the humeral shaft include:

1. Anterolateral approach: preferred for proximal third humeral shaft fractures; radial nerve identified in the interval between the brachialis and brachioradialis and traced proximally. The brachialis muscle is split to afford access to the shaft. This can be extended proximally to the shoulder.

2. Anterior approach: muscular interval between the biceps and brachialis muscles

3. Posterior approach: provides excellent exposure to most of the humerus, including the elbow, but cannot be extended proximally to the shoulder; muscular interval is between the lateral and long heads of the triceps. The medial head is split. The radial nerve must be identified in the spiral groove usually at the midportion of the arm.

Patient Positioning

Supine on a radiolucent table

• Used for anterior or anterolateral approach

• Quick and easy setup

• Good for multiply injured patients with multiple extremity involvement

Beach chair

• Used for anterolateral approach

• Good when fracture extends into shoulder region, as it can be extended into deltopectoral approach

• Weight of arm may be used to help reduce fracture

Lateral

• Used for posterior approach

• Good when fracture extends into elbow region

Prone

• Used for posterior approach

• Good when fracture extends into elbow region

   

  Image Positioning

Image intensifier can be placed on same or opposite side of the injured extremity

Surgical Techniques

Open Reduction and Plate Fixation

Associated with the best functional results. It allows direct fracture reduction and stable fixation of the humeral shaft without violation of the rotator cuff.

Radiographs of the uninjured, contralateral humerus may be used for preoperative templating.

A 3.5- or 4.5-mm dynamic compression plate (large fragment) with fixation of six to eight cortices proximal and distal to the fracture is typically used (Fig. 16.2).

Lag screws should be utilized whenever possible.

One should preserve soft tissue attachments to butterfly fragments.

One should consider bridge plating if there is considerable fracture comminution. The plate is used to span the area of injury with avoidance of soft tissue dissection and devascularization at the fracture site. Fracture healing will proceed by callus formation, not primary bone healing.

Use of locked plates has grown in popularity, particularly in osteopenic or compromised bone.

Recent series reporting good results with use of percutaneous submuscular plating for stabilization of humeral shaft fractures.

Intramedullary Fixation

Indications include:

Segmental fractures in which plate placement would require considerable soft tissue dissection

Humerus fractures in extremely osteopenic bone

Pathologic humerus fractures

Interlocked nails

• Current humeral nails have proximal and distal interlocking capabilities and are able to provide rotational and axial fracture stability (Fig. 16.3).

• With antegrade nailing, the axillary nerve is at risk for injury during proximal locking screw

  insertion. Screws protruding beyond the medial cortex may potentially impinge on the axillary nerve during internal rotation. Anterior to posterior screws are avoided because of the potential for injury to the main trunk of the axillary nerve.

• Distal locking usually consists of screws in the AP plane. Distal locking screw can be inserted anterior to posterior or posterior to anterior via an open technique to minimize the risk of neurovascular injury. Lateral to medial screws risk injury to lateral antebrachial cutaneous nerve and the radial nerve.

   

   

   

Current antegrade nailing techniques try to avoid entry site placement at the rotator cuff insertion to

minimize postoperative shoulder problems.

The proximal aspect of the nail should be countersunk to prevent subacromial impingement.

External Fixation (Fig. 16.4)

Indications include:

• Infected nonunions

• Burn patients with fractures

• Open fractures with extensive soft tissue loss

Complications include pin tract infection, neurovascular injury, and nonunion.

Postoperative Rehabilitation

Range-of-motion exercises for the hand and wrist should be started immediately after surgery;

shoulder and elbow range of motion should be instituted as pain subsides.

COMPLICATIONS

Radial nerve injury occurs in up to 18% of cases.

• Most common with middle third fractures, although best known for its association with Holstein-Lewis–type distal third fracture, which may entrap or lacerate the nerve as it passes through the intermuscular septum.

• Most injuries are neurapraxias or axonotmesis; function should return within 3 to 4 months; laceration is more common in penetrating trauma.

• With secondary palsies that occur during fracture reduction, it has not been clearly established

  that surgery will improve the ultimate recovery rate compared with nonsurgical management.

• Delayed surgical exploration should be done after 3 to 4 months if there is no evidence of recovery by electromyography or nerve conduction velocity studies.

• Advantages of late over early nerve exploration:

  • Enough time will have passed for recovery from neurapraxia or neurotmesis.

  • Precise evaluation of a nerve lesion is possible.

  • The associated fracture may have united.

  • The results of secondary nerve repair are as good as those of primary repair.

Vascular injury: This is uncommon but may be associated with fractures of the humeral shaft lacerating or impaling the brachial artery or with penetrating trauma.

• The brachial artery has the greatest risk for injury in the proximal and distal third of the arm.

• It constitutes an orthopaedic emergency; arteriography is controversial because it may prolong time to definitive treatment for an ischemic limb.

• Arterial inflow should be established within 6 hours.

• At surgery, the vessel should be explored and repaired and the fracture stabilized.

• If limb viability is not in jeopardy, bone repair may precede vascular repair.

• External fixation should be considered an option.

• With prolonged ischemia, one should consider reperfusion injury and the potential need for fasciotomies.

Nonunion occurs in up to 15% of cases.

• Risk factors include fracture at the proximal or distal third of the humerus, transverse fracture pattern, fracture distraction, soft tissue interposition, and inadequate stabilization/immobilization.

• It may necessitate open reduction and internal fixation with bone grafting.

Malunion: This may be functionally inconsequential; arm musculature and shoulder, elbow, and trunk range of motion can compensate for angular, rotational, and shortening deformities.