Upper limb injuries and deformities

Overview

A limb injury is easier to understand when you know what lies beside the damaged bone or joint. Fracture fragments can injure a nearby nerve or artery; a torn tendon removes a specific movement.

Deformity reflects both the original force and the pull of surviving muscles.

For each injury, ask four questions: what structure failed, which neighbour is at risk, which function is lost, and what sign follows?

This page explains those anatomical connections rather than providing a fracture-treatment protocol.

Shoulder girdle and humerus

A clavicle commonly fractures around the junction of its middle and lateral thirds. Sternocleidomastoid elevates the medial fragment; the weight of the limb depresses the lateral fragment, which may be drawn medially.

The subclavian vessels and brachial plexus lie below and behind the clavicle and are potentially vulnerable.

A direct fall onto the shoulder can separate the acromioclavicular joint. Disruption of the coracoclavicular ligament allows the scapula and attached limb to descend relative to the clavicle.

Posterior sternoclavicular displacement is particularly important because major vessels and other mediastinal structures lie behind the joint.

Anteroinferior shoulder dislocation often follows forced abduction and external rotation. The humeral head moves through the less reinforced inferior capsule.

Axillary nerve injury can produce deltoid weakness and altered sensation over the lateral shoulder.

Posterior dislocation may follow a seizure or electrical injury, when strong internal rotators overpower external rotators. The arm is typically held internally rotated with restricted external rotation.

The direction must be established rather than assumed from the injury label.

An association is a warning about what to examine, not a claim that every fracture at that site causes that nerve injury.

Elbow and forearm injury patterns

A supracondylar fracture in a child can displace the distal humeral fragment posteriorly. The proximal fragment can threaten the anterior neurovascular structures.

Swelling, evolving nerve findings and perfusion changes matter even when the initial appearance seems reassuring.

In elbow extension, the medial epicondyle, lateral epicondyle and olecranon normally lie in a line. In flexion they form a triangle.

A dislocation disturbs this relationship; a supracondylar fracture may preserve the relationship among the three distal landmarks.

Monteggia and Galeazzi injuries each combine a forearm fracture with disruption at the other bone's joint. This is why both ends of the forearm need assessment.

These names describe recognisable patterns. They do not replace description of the fracture location, displacement, joint involvement and neurovascular findings.

Scaphoid, carpus and metacarpals

A fall onto an outstretched hand may fracture the scaphoid waist. Tenderness in the anatomical snuffbox or over the palmar scaphoid tubercle raises suspicion. An initially normal radiograph does not exclude the injury.

Much of the scaphoid's blood enters distally and travels towards the proximal pole. A waist fracture can interrupt this supply, putting the proximal fragment at risk of non-union and avascular necrosis.

This is the key vascular explanation, rather than simply memorising that scaphoid fractures are troublesome.

In a lunate dislocation the lunate may move towards the palm and compress the median nerve in the carpal tunnel.

In a perilunate dislocation the surrounding carpus displaces while the lunate initially retains its relationship with the radius. Both require careful carpal alignment assessment.

A fracture of the hook of hamate may follow force through a racket or bat. The ulnar nerve and artery lie close to it in Guyon's canal, while flexor tendons also pass nearby.

Symptoms can therefore include ulnar nerve dysfunction as well as local pain.

A boxer's fracture usually affects the fifth metacarpal neck. Rotation matters: when the fingers flex, an injured digit may cross its neighbour even if the resting deformity looks small.

Malunion above the elbow can alter the carrying angle: cubitus varus turns the forearm medially, while cubitus valgus exaggerates lateral angulation. Valgus deformity can stretch the ulnar nerve over time.

Tendon and fascial deformities

A boutonnière posture may develop after the initial central-slip injury rather than appearing immediately. Active and passive examination help distinguish tendon failure from a fixed joint contracture.

Nerve-related postures

A proximal median lesion can produce the “hand of benediction” when the patient attempts to make a fist: index and middle finger flexion is impaired.

It is an attempted movement sign, not the usual resting posture of carpal tunnel syndrome.

Ulnar clawing is a resting imbalance with metacarpophalangeal hyperextension and interphalangeal flexion. It may be greater after a distal lesion because profundus remains functional.

These two signs should not be used interchangeably.

Clinical relevance

Compartment syndrome

How it happens: Swelling or bleeding raises pressure inside a closed fascial compartment and reduces tissue perfusion.

What you see: Severe pain, especially with passive muscle stretch, may precede weakness or sensory loss. Pulses can remain palpable despite threatened muscle circulation.

Volkmann's ischaemic contracture

How it happens: Forearm ischaemia causes muscle necrosis, followed by fibrosis and shortening of the flexors.

What you see: The wrist and fingers become fixed in flexion. This late contracture differs from an acute nerve palsy.

Rotator cuff rupture and biceps rupture

How it happens: A cuff tendon tears, or the long-head biceps tendon ruptures and releases its muscle attachment.

What you see: Cuff injury weakens its corresponding movement. Long-head rupture can create a distally bunched “Popeye” contour, while brachialis and the remaining biceps head preserve some elbow flexion.

Quick revision

• Surgical neck threatens axillary nerve; humeral shaft threatens radial nerve.
• Supracondylar displacement threatens brachial artery and median/AIN function.
• Monteggia combines ulna fracture with radial-head dislocation.
• Galeazzi combines radius fracture with distal radioulnar disruption.
• Scaphoid proximal pole is vulnerable after blood-supply interruption.
• Mallet loses distal extension; jersey finger loses distal flexion; normal pulses do not exclude compartment syndrome.

Sources: Snell's Clinical Anatomy by Regions, supplied Upper Limb chapter; UHS PGET Paper I MBBS Table of Specifications. Supplementary clinical testing and developmental context follow standard examination conventions and Duke Embryology where relevant. Picture links are visual study resources. Text and tables written independently for The House Job.

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