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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Humeral-shaft fracture and radial-nerve injury

Musculoskeletal medicine and orthopaedics · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
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Open, vascular or progressive nerve injury

Most closed primary radial palsies recover, but open wounds, arterial compromise, penetrating trauma or a new deficit after manipulation can indicate laceration or entrapment needing urgent action.

Action: Perform ABCDE after high energy, cover open wounds and give intravenous prophylaxis within one hour, document pulses and named radial, median and ulnar functions, align and splint, and seek immediate orthopaedic, vascular or nerve input for tissue threat.

Overview

Stabilise humeral-shaft fracture, document radial and wider neurovascular function accurately, distinguish primary from new iatrogenic palsy, and select functional bracing, fixation or nerve exploration safely.

Describe fracture level, pattern, comminution, displacement, open status and pathological features. Radial palsy may be present at injury, appear after manipulation or develop after surgery; timing changes concern. Document nerve functions before analgesia and every intervention so the distinction is credible. Motor testing is more informative than asking only about numbness: assess wrist, finger and thumb extension and note whether wrist extension deviates radially.

Most closed fractures can unite with functional bracing, but treatment must preserve shoulder and elbow motion and monitor alignment. Primary closed radial palsy often represents neurapraxia and recovers with observation. New or worsening deficit, open injury or vascular damage requires immediate specialist review. Persistent absent recovery prompts electrodiagnostic and imaging decisions at defined intervals. Pathological fracture requires tumour-aware planning before an unconsidered nail or plate contaminates tissue planes.

Practice

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Musculoskeletal medicine and orthopaedicsOriginal SBA

Primary radial palsy

A closed midshaft humeral fracture has wrist and finger extension weakness documented before any manipulation, with normal perfusion. What is the usual initial nerve-management principle?

Choose one answer, then submit
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • AO Surgery Reference humeral-shaft fractures
  • BOAST peripheral nerve injury
  • BOAST open fractures
  • NICE NG38 fractures non-complex assessment and management

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom

Initial splintage controls pain and gross deformity while swelling settles. Functional bracing then applies circumferential support while leaving shoulder and elbow free, using gravity and muscle activity to align the shaft. Review skin, brace fit and radiographs early because obesity, large breasts, very proximal or distal fracture, comminution and inability to follow adjustments can reduce control. Acceptable angulation is a clinical and specialist judgement; rotational deformity and persistent distraction are poorly tolerated and cannot be assessed from one projection alone.

Map radial recovery sequentially. Brachioradialis and wrist extensors may recover before finger and thumb extension, while Tinel progression can support regeneration. Provide a cock-up wrist splint and maintain full passive finger and thumb range to prevent contracture and preserve grasp. If no clinical recovery appears at the expected interval, the specialist team may use ultrasound, MRI neurography or electrodiagnostic studies to locate continuity and plan exploration, graft or tendon transfer. Testing too early can be non-diagnostic and should follow the nerve pathway.

Operative fixation is selected for open fracture, arterial repair, polytrauma mobilisation, segmental or bilateral injury, pathological bone, failure of acceptable closed alignment or established nonunion. Plate fixation permits direct control of rotation and nerve inspection where indicated; intramedullary nailing offers another load-sharing option but can affect shoulder function. Exploration is especially considered when the nerve is exposed by the wound, lacerated, associated with vascular injury, or becomes newly deficient after intervention. The operative note should state nerve appearance and relationship to implants.

Recovery surveillance extends beyond union. Compare shoulder elevation, elbow extension, forearm rotation and hand opening; a united shaft with stiff neighbouring joints remains a poor outcome. Persistent pain or movement raises nonunion concern and requires mechanical, infection and metabolic assessment. After fragility or atypical fracture, investigate bone health, medicine exposure and the opposite femur or humerus when symptoms suggest a systemic process. In pregnancy or renal disease, adjust analgesia, imaging and thromboprophylaxis while maintaining the same limb-safety priorities.

Nonunion assessment separates mechanics from biology. Review original pattern, gap, implant stability, smoking, infection risk, nutrition, diabetes and medication exposure. Obtain orthogonal radiographs and, when needed, CT to define bridging. Infection work-up uses symptoms, wound history and appropriate blood and deep tissue sampling rather than superficial swabs alone. Revision may require compression, bone graft and different fixation, but treating infection and host factors is equally important. The patient needs realistic advice about work restriction and the staged nature of revision rather than endless brace continuation.

Radial palsy safety-netting is practical. Return urgently for new loss of wrist or finger extension, spreading numbness, severe brace pain or hand colour change. During observation, inspect the splint and skin and maintain supple MCP, PIP, DIP and thumb joints. Recovery is charted by muscle grade and distribution, not merely whether tingling is present. If tendon transfer becomes necessary after failed nerve recovery, preserved passive motion and strong donor muscles determine function, which is why early therapy remains valuable even before the final nerve outcome is known.

Key points

  • Inspect the whole arm for wounds, deformity and skin pressure and examine shoulder and elbow because associated joint injury changes care.
  • Before and after splintage, test wrist extension, finger MCP extension, thumb extension, dorsal first-web sensation, median and ulnar functions, pulses and refill.
  • Obtain AP and lateral radiographs of the full humerus including shoulder and elbow; pathological features may require staging before definitive fixation.
  • A closed primary radial palsy is commonly observed with fracture treatment and serial recovery assessment rather than explored automatically.
  • Open fracture, vascular injury, penetrating laceration, irreducible entrapment or a new post-manipulation palsy lowers the threshold for urgent exploration.
  • Many closed suitable fractures use initial splintage followed by a functional brace, with early shoulder and elbow movement and alignment review.
  • Operative fixation is considered for open, vascular, pathological, polytrauma, segmental, failed closed or functionally unacceptable patterns.
  • Provide a wrist-extension splint and hand therapy for radial palsy to preserve grasp, joint position and passive range during nerve recovery.

Aetiology

01

Direct bending trauma

A direct blow or collision bends the humeral shaft, producing transverse or comminuted fracture with variable soft-tissue and radial-nerve injury.

02

Torsional fall

A fall onto the arm applies rotation, commonly creating a spiral pattern through the middle or distal third.

03

Pathological fracture

Minimal force with preceding pain or abnormal bone can indicate metastasis, myeloma or another lesion requiring planned biopsy and fixation strategy.

Pathophysiology

  1. 1
    Radial-nerve proximity

    The nerve travels in the spiral groove and crosses the lateral intermuscular septum, making it vulnerable in middle and distal shaft injury.

  2. 2
    Motor interruption

    Radial dysfunction weakens wrist, finger and thumb extension, producing wrist drop and impaired hand opening despite preserved finger flexion.

  3. 3
    Sensory change

    The autonomous sensory territory is the dorsal first web space, although overlap means motor testing is essential for reliable documentation.

  4. 4
    Fracture healing

    Relative stability in a functional brace permits callus while gravity and muscle tone restore alignment; distraction, infection and smoking impair union.

Clinical features and red flags

Shaft fractureRed flag

Arm pain, swelling, shortening, angulation and crepitus follow direct or torsional trauma.

Radial palsyRed flag

Wrist, finger and thumb extension weakness with dorsal first-web sensory change produces wrist drop.

Primary neurapraxia

Radial weakness present before treatment in a closed fracture often reflects stretch or contusion and may recover.

Secondary palsyRed flag

A new deficit after manipulation, brace fitting or fixation raises concern for compression, entrapment or iatrogenic injury.

Arterial injuryRed flag

Pulse loss, coolness, delayed refill or expanding swelling requires immediate limb-saving coordination.

Red flags requiring action

  • A cool hand, absent pulse, expanding arm haematoma or recurrent bleeding requires immediate realignment and combined vascular and orthopaedic assessment.
  • A wound near the shaft, penetrating mechanism or exposed bone triggers the open long-bone pathway and early antibiotic prophylaxis.
  • A radial deficit first appearing after reduction, splintage or fixation requires urgent reassessment for entrapment, compression or iatrogenic injury.

Investigations

  1. 01
    Full-length AP and lateral humeral radiographsFirst step
    Why
    Define fracture and include both shoulder and elbow joints.
    Interpretation and limitations
    Assess length, angulation, rotation, comminution and abnormal bone; correlate alignment with function.
  2. 02
    Serial named nerve examination
    Why
    Establish injury timing and monitor radial, median and ulnar motor and sensory function.
    Interpretation and limitations
    Write individual movements and territories rather than a global normal label.
  3. 03
    CT angiography when arterial injury is suspected
    Why
    Locate vessel damage in a stable enough patient after urgent realignment.
    Interpretation and limitations
    Hard signs and persistent ischaemia can require direct operative treatment without imaging delay.
  4. 04
    Electrodiagnostic testing for delayed recovery
    Why
    Assess reinnervation and lesion severity when clinical recovery does not appear as expected.
    Interpretation and limitations
    Timing is specialist directed because very early testing may not define axonal loss fully.

Differential diagnosis

01

Posterior interosseous palsy

Finger and thumb extension are weak but wrist extension may remain through extensor carpi radialis longus, and cutaneous sensation is spared.

02

Brachial-plexus injury

Weakness and sensory loss across radial, median and ulnar territories suggests broader traction injury rather than isolated spiral-groove dysfunction.

03

Cervical radiculopathy

Neck pain, reflex change and a myotomal pattern can mimic radial weakness but does not explain the acute shaft deformity.

04

Compartment or vascular injury

Escalating pain, swelling, coolness, delayed refill or deteriorating function may reflect acute ischaemia rather than an isolated radial neurapraxia.

Management

01First assessmentAlign and map nerve functionFirst stepA humeral-shaft fracture is suspected after trauma.+
  1. 1Use ABCDE for high energy, expose wounds and inspect shoulder, arm and elbow.
  2. 2Give analgesia and document pulses and radial, median and ulnar motor and sensory findings.
  3. 3Obtain full-length films, align and splint and repeat the identical examination.
02Closed suitable fractureBrace and preserve adjacent motionThe fracture is closed and acceptably aligned without vascular or tissue threat.+
  1. 1Transition from initial splint to functional brace according to swelling and fracture review.
  2. 2Encourage hand, wrist, elbow and shoulder movement within the stability plan and support radial palsy with a wrist splint.

Complications

01

Radial-nerve palsy

Neurapraxia commonly recovers, while laceration, entrapment or failure of reinnervation can leave persistent wrist and finger extension loss.

02

Nonunion

Transverse pattern, distraction, smoking, infection or instability can produce persistent pain and movement requiring revision strategy.

03

Malunion

Some angulation is functionally tolerated, but substantial rotational error or shortening impairs shoulder and elbow mechanics and visible arm alignment.

04

Shoulder and elbow stiffness

Pain and prolonged immobilisation restrict both neighbouring joints, making early hand, wrist and joint rehabilitation important.

Monitoring and follow-up

  • Repeat wrist, finger and thumb extension and dorsal first-web sensation after every intervention.
  • Check brace skin pressure, swelling and distal perfusion as oedema changes.
  • Measure shoulder and elbow motion and provide hand therapy during nerve recovery.
  • Use serial radiographs and tenderness to assess alignment and union.
  • Escalate new palsy, absent recovery, persistent fracture movement or infection signs through the named specialist pathway.

Special situations

Timing classifies the palsy

A deficit present before treatment has a different risk profile from weakness first detected after reduction or surgery.

First web space is autonomous

This dorsal sensory area is useful, but preserved sensation never substitutes for wrist and finger motor testing.

Brace works dynamically

Functional support allows gravity and muscle activity to align the shaft while avoiding complete shoulder and elbow immobilisation.

Wrist support preserves hand use

Holding the wrist extended lets finger flexors generate grasp while denervated extensors recover.

Common pitfalls

  1. 01

    Recording only hand sensation and missing radial motor weakness before manipulation.

  2. 02

    Exploring every closed primary palsy automatically without considering its high spontaneous recovery rate.

  3. 03

    Reassuring a new post-reduction palsy as routine without urgent reassessment.

  4. 04

    Taking a cropped shaft film that excludes the shoulder or elbow.

  5. 05

    Immobilising the whole upper limb until union and creating avoidable joint stiffness.

3
EscalationReview alignment, skin, union and nerve recovery at defined intervals and escalate loss of position or nonunion.
03Urgent operative patternFix bone and address nerve or vesselOpen injury, vascular compromise, new palsy, pathological bone or unstable pattern is present.+
  1. 1Start open-fracture or vascular protocols immediately and avoid serial referral delay.
  2. 2Plan fixation with direct nerve inspection when indication and mechanism support exploration.
  3. 3Document operative nerve continuity, postoperative function and a specific recovery or reconstruction follow-up plan.
Key medicines and prescribing safety2 treatments · regimens, roles and cautions+
Provides baseline analgesia supporting splint tolerance and movement.

Paracetamol for adult arm-fracture pain

For an adult, prescribe 500 mg to 1 g orally as required, with a minimum 4-hour interval and a maximum of four administrations in one day.

Reduce the limit in low body weight or hepatic risk and count all combination products.

Reduces infection risk before operative wound excision and fixation.

Intravenous prophylaxis for an open humerus

Give the locally approved intravenous open-fracture agent and dose as soon as possible and within 1 hour, adjusted for allergy, renal function and contamination.

Do not delay for imaging or cultures, and do not use continued antibiotics to compensate for inadequate excision.