Orthopaedic Surgery - Humeral Shaft Fracture

Basics

A humeral shaft fracture is a fracture involving the diaphysis of the humerus, extending between the proximal and distal metaphyseal regions.

These fractures occur across all age groups and may result from low-energy or high-energy mechanisms depending on the patient.

Classification

Humeral shaft fractures can be described according to the AO classification, anatomic location, fracture pattern, soft-tissue status, and underlying bone quality.

Anatomic Location

Fractures may involve the:

Proximal one-third, middle one-third, or distal one-third of the humeral shaft.

Fracture Pattern

Common configurations include:

Transverse, oblique, spiral, comminuted, and segmental fractures.

Open Versus Closed

The skin and soft tissues should be examined carefully to determine whether the fracture is:

Closed or open.

An open fracture communicates with the external environment and requires urgent antibiotic administration, tetanus assessment, and operative debridement.

Pathologic Fracture

A fracture occurring through abnormal bone may represent an underlying:

Tumor, metastatic lesion, metabolic bone disease, or other pathologic process.

Holstein–Lewis Fracture

A spiral fracture involving the distal one-third of the humeral shaft is traditionally called a Holstein–Lewis fracture.

This pattern is clinically important because the radial nerve lies close to the distal humerus and may be injured or entrapped.

Epidemiology

Humeral shaft fractures are relatively uncommon.

Historical estimates place the annual incidence at approximately 0–2 per 10,000 people, with no major overall sex difference.

Distribution

Midshaft fractures account for approximately 40% of humeral fractures in some series.

Age Distribution

The incidence demonstrates a bimodal pattern.

A first peak occurs in younger adults, often related to high-energy trauma.

A second peak occurs in older adults, particularly women in approximately the seventh decade of life, where osteoporosis and low-energy falls become more important.

Pediatric Population

Humeral fractures represent an important proportion of pediatric fractures and have historically accounted for approximately 17% of fracture-related admissions in children in some series.

Risk Factors

Important risk factors include:

Osteoporosis in older adults, high-energy trauma in younger patients, falls from height, motor vehicle collisions, and sports involving strong torsional forces.

Sports

Rotational stresses generated during activities such as:

Wrestling, baseball, softball throwing, and similar sports

may occasionally produce spiral humeral shaft fractures.

Etiology

Most humeral shaft fractures are caused by a direct blow or substantial force applied to the upper extremity.

Direct Trauma

Direct impact commonly produces a transverse or comminuted fracture.

Twisting Injury

Torsional loading can produce spiral or oblique fracture patterns.

Violent Muscle Contraction

Rarely, forceful muscular contraction may generate enough torsional stress to fracture the humerus.

This has been described during throwing activities.

Pathologic Bone

Patients with abnormal or weakened bone may sustain a fracture after relatively minor trauma.

Associated Conditions

Because substantial trauma may be involved, the entire upper extremity should be examined for additional injuries.

Associated injuries may include fractures or soft-tissue damage involving the:

Shoulder, clavicle, elbow, forearm, wrist, or hand.

Neurovascular Injury

A careful neurovascular examination is essential.

The radial nerve deserves particular attention because of its close relationship to the humeral shaft.

Diagnosis

Signs and Symptoms

Typical findings include:

Pain, swelling, bruising, deformity, abnormal motion, and occasionally crepitus.

Patients usually support the injured arm with the opposite hand and avoid movement because of pain.

Physical Examination

Skin Integrity

The skin should be examined carefully for:

Open wounds, punctures, abrasions, tenting, threatened skin, or severe soft-tissue injury.

Any wound near the fracture should be assumed to represent a possible open fracture until proven otherwise.

Examination of Adjacent Joints

The shoulder and elbow should be assessed.

The clavicle, forearm, wrist, and hand should also be examined for associated trauma.

Neurologic Examination

Motor and sensory function of the:

Radial, median, and ulnar nerves

should be documented before and after any reduction or immobilization.

Radial Nerve Examination

The radial nerve is the nerve most commonly injured.

Motor testing should include:

Wrist extension, finger MCP extension, and thumb extension.

Sensory examination should include the dorsal first web space.

Median Nerve Examination

Median nerve function can be assessed through:

Thumb opposition, thumb IP flexion, index finger flexion, and sensation over the palmar radial digits.

Ulnar Nerve Examination

Ulnar nerve testing includes:

Finger abduction and adduction and sensation over the little finger.

Vascular Examination

The radial pulse should be palpated.

Capillary refill, skin temperature, and color should also be documented.

Any evidence of vascular compromise requires urgent evaluation.

Laboratory Tests

No laboratory test is diagnostic of an isolated humeral shaft fracture.

Laboratory studies are obtained when indicated by:

Trauma severity, suspected pathologic fracture, operative planning, or associated medical conditions.

Imaging

Plain Radiographs

Standard imaging includes:

AP and lateral views of the entire humerus.

The shoulder and elbow joints should be included to ensure that associated injuries are not missed.

Additional Imaging

CT or MRI is not routinely required for a straightforward shaft fracture.

Advanced imaging may be useful when evaluating:

Complex fracture extension, pathologic lesions, occult articular involvement, or associated soft-tissue abnormalities.

Differential Diagnosis

Important alternatives include:

Pathologic fracture through abnormal bone, muscular contusion, muscle strain or tear, and other upper-arm soft-tissue injuries.

Treatment

Most closed humeral shaft fractures can be treated successfully without surgery.

The humerus tolerates a moderate degree of shortening and angular deformity because shoulder and elbow motion compensate well.

Acceptable Alignment

Historical nonoperative guidelines have accepted approximately:

Up to 20–30° of angulation, up to 2–3 cm of shortening, and approximately 15° of rotational deformity, depending on fracture location and patient factors.

Greater deformity may require reduction or operative stabilization.

Initial Immobilization

Acute fractures are commonly immobilized initially with a coaptation or U-shaped splint.

U-Splint

The splint extends from the axilla, around the elbow, and upward along the lateral aspect of the arm toward the shoulder.

Its purpose is to provide circumferential support while allowing swelling.

Posterior Splint

A posterior slab may be added for additional stability.

The arm is then supported in a sling.

Functional Fracture Brace

After approximately 1–2 weeks, once swelling has decreased and pain is improving, many fractures can be transitioned to a functional humeral fracture brace.

Duration

Bracing is continued until there is adequate:

Clinical stability, absence of significant fracture-site pain, and radiographic evidence of healing.

This commonly requires at least 6–8 weeks, with some fractures taking longer.

Union Rate

Traditional functional bracing has produced union rates of approximately 90% in many series, although the risk varies with fracture pattern and patient characteristics.

Indications for Operative Treatment

Surgery may be considered for:

Open fractures, vascular injury, significant associated articular injury, ipsilateral forearm fracture, segmental fracture, multiple extremity injuries, inability to obtain or maintain acceptable alignment, certain pathologic fractures, and selected nerve injuries.

Floating Elbow

An ipsilateral humeral shaft and forearm fracture creates a floating elbow and often requires operative stabilization.

Secondary Radial Nerve Palsy

A radial nerve palsy that develops after manipulation or reduction raises concern for entrapment or iatrogenic injury and may warrant surgical exploration depending on the clinical situation.

Activity

The injured arm is supported in a sling initially.

The sling should be used for comfort rather than prolonged rigid immobilization once safe motion is permitted.

Nursing and Acute Care

Ice can be applied for approximately 15–20 minutes at a time during the acute phase to reduce pain and swelling.

The skin, particularly in the axilla beneath the splint or brace, should be kept clean and dry.

Fracture Motion

Patients may occasionally feel minor movement or clicking at the fracture site during the early healing period.

This can occur before callus formation but should be reassessed if associated with increasing pain, deformity, or loss of alignment.

Physical Therapy

Formal physical therapy is usually unnecessary during the earliest phase.

Once pain begins to settle, typically after approximately 1–2 weeks, gentle motion of the:

Shoulder, elbow, wrist, and hand

should begin as permitted.

Goals

Early controlled motion helps prevent:

Shoulder stiffness, elbow stiffness, muscle atrophy, and loss of hand function.

Medication

Analgesia is tailored to pain severity.

Short-term opioid medication may occasionally be required for severe acute pain.

Acetaminophen and other appropriate analgesics may also be used.

Surgery

Operative stabilization can be achieved by:

Plate-and-screw fixation, intramedullary nailing, or, rarely, external fixation.

Plate Fixation

Open reduction and internal fixation may use:

A 4.5-mm dynamic compression plate, locking compression plate, or other appropriate plate construct.

Plate fixation provides direct control of alignment and permits radial nerve exploration when necessary.

Intramedullary Nailing

An intramedullary nail may be inserted through either an antegrade or retrograde approach, depending on fracture anatomy and surgeon preference.

Antegrade Nailing

Antegrade insertion passes through the proximal humerus near the shoulder.

It may be associated with postoperative shoulder pain or rotator cuff irritation if the entry site or implant prominence affects the cuff.

Retrograde Nailing

Retrograde insertion avoids the proximal rotator cuff but has its own technical limitations and potential complications.

External Fixation

External fixation is rarely required but may be useful in situations involving:

Severe soft-tissue injury, major contamination, vascular reconstruction, damage-control orthopaedics, or selected open fractures.

Follow-Up

Prognosis

Most isolated closed humeral shaft fractures heal successfully.

Nonoperative treatment historically produces union in approximately 90% of cases.

Radial Nerve Injury

Radial nerve palsy is one of the most important complications.

It occurs in approximately 10–12% of humeral shaft fractures in historical series.

Timing

Radial nerve dysfunction may occur:

At the time of injury, during manipulation, or during operative treatment.

Primary Radial Nerve Palsy

A radial nerve palsy present at initial presentation in a closed fracture is commonly a neurapraxia or axonotmesis and often recovers spontaneously.

Observation is appropriate in many cases if there are no additional indications for exploration.

Secondary Radial Nerve Palsy

New radial nerve palsy developing after reduction or fixation raises greater concern for nerve entrapment, laceration, or implant-related injury and warrants prompt reassessment.

Recovery

Approximately 70% or more of radial nerve injuries associated with humeral shaft fractures are neurapraxic or otherwise recover without nerve repair.

Clinical recovery may take weeks to months.

Nonunion

Failure of the fracture to unite may occur, particularly with:

Marked distraction, transverse fracture patterns, proximal-third fractures, smoking, open injury, poor biology, or inadequate stability.

Historical literature suggested higher nonunion rates with certain intramedullary techniques, although outcomes depend heavily on modern implant design and patient selection.

Malunion

Mild angular deformity is often well tolerated because of the broad compensatory motion available at the shoulder and elbow.

More severe rotational or angular deformity may produce functional or cosmetic problems.

Shoulder Pain

Shoulder discomfort may develop after humeral shaft fracture because of:

Prolonged immobilization, altered mechanics, adhesive stiffness, or antegrade nail entry through the rotator cuff.

Elbow Stiffness

Elbow stiffness may result from prolonged immobilization and is minimized by beginning controlled motion as soon as fracture stability permits.

Patient Monitoring

Serial clinical and radiographic follow-up is necessary to confirm progressive healing.

Radiographic Follow-Up

Radiographs are commonly obtained every 4–6 weeks during early healing.

They should demonstrate:

Maintenance of acceptable alignment, increasing callus formation, and progressive union.

Range of Motion

Shoulder and elbow motion should be assessed at each follow-up visit.

If stiffness develops, the rehabilitation program should be adjusted.

Neurovascular Monitoring

Radial nerve function should be followed carefully, documenting recovery of:

Wrist extension, finger extension, thumb extension, and dorsal hand sensation.

Failure of neurologic recovery over an appropriate interval may warrant electrodiagnostic testing or further specialist evaluation.