Upper limb bones and fractures
Upper limb bones, joints and fractures: structures at risk for FCPS
Upper limb bones, joint types and fractures for FCPS Part 1, with the nerve or vessel each fracture puts at risk. Every injury question links a mechanism, a deformity and the structure lying against the bone, from clavicle to metacarpals.
Joint types you must classify
| Class | Type | Upper limb example | Other classic example |
|---|---|---|---|
| Fibrous | Syndesmosis (bones held by an interosseous ligament or membrane) | Middle radioulnar union (interosseous membrane) | Inferior tibiofibular joint; high ankle sprain injures it |
| Fibrous | Suture, gomphosis | None | Skull sutures; tooth in its socket |
| Cartilaginous | Primary (hyaline, synchondrosis) | Growth plates | First sternocostal joint |
| Cartilaginous | Secondary (fibrocartilage, symphysis) | None | Pubic symphysis, intervertebral discs |
| Synovial | Saddle | Sternoclavicular, first carpometacarpal (allows opposition) | Calcaneocuboid |
| Synovial | Plane | Acromioclavicular, intercarpal | Facet joints |
| Synovial | Ball and socket | Glenohumeral | Hip |
| Synovial | Hinge | Elbow (humeroulnar), interphalangeal | Ankle |
| Synovial | Pivot | Proximal and distal radioulnar | Atlantoaxial (median) |
| Synovial | Condyloid/ellipsoid | Wrist (radiocarpal), metacarpophalangeal | Atlanto-occipital |
Clavicle
- The first bone to ossify (membranous, fifth week) and the last to complete fusion (medial epiphysis about 25 years).
- Absent or small in cleidocranial dysplasia (RUNX2 mutation), with open fontanelles and dental abnormalities.
- Commonest fracture site: the middle third. The medial fragment is pulled up by sternocleidomastoid; the lateral fragment is pulled down by the weight of the arm and medially by pectoralis major. The subclavian vessels and brachial plexus lie behind but are rarely hurt.
- The coracoclavicular ligament (conoid and trapezoid) is the main stabiliser of the AC joint. In AC separation, with the lateral end of the clavicle riding up over the acromion, the AC capsule tears first and the coracoclavicular ligament in severe grades.
Scapula
- Coracoid: pectoralis minor, short head of biceps, coracobrachialis. Acromion and spine: deltoid and trapezius. Medial border: levator scapulae, rhomboids, serratus anterior. Supraglenoid tubercle: long head of biceps; infraglenoid tubercle: long head of triceps.
- Fractures need high-energy trauma, so look for rib, lung and thoracic injuries.
Shoulder dislocation
- The glenoid is shallow and the inferior capsule has no rotator cuff support; a fall on an abducted, externally rotated arm levers the head out anteroinferiorly (over 95% are anterior).
- The inferior glenohumeral ligament (its anterior band) and the anteroinferior labrum are the structures torn; detachment of the labrum is the Bankart lesion, the commonest reason a young athlete keeps dislocating with less and less force. The Hill–Sachs lesion is a dent in the posterolateral head.
- Nerve at risk: axillary nerve (numb regimental badge, weak deltoid). In patients over 40, persistent weakness is more often a rotator cuff tear.
- Posterior dislocation follows seizures or electric shock; arm locked in medial rotation, "light bulb" head on the AP film; often missed.
Humerus: what lies against each part
| Fracture site | Structure at risk | Clinical result |
|---|---|---|
| Anatomical neck (rare, elderly) | Blood supply of the head | Avascular necrosis |
| Surgical neck | Axillary nerve, posterior circumflex humeral artery | Weak abduction, numb regimental badge |
| Midshaft (spiral groove) | Radial nerve, profunda brachii | Wrist and finger drop; triceps spared because its branches arise in the axilla, above the groove |
| Distal third (spiral) | Radial nerve tethered at the lateral intermuscular septum | Nerve caught between fragments |
| Supracondylar (child) | Brachial artery, median and anterior interosseous nerves | Pulseless hand, Volkmann contracture, no "OK" sign |
| Medial epicondyle | Ulnar nerve, ulnar collateral artery | Numb little finger; a blow to a child's elbow with displacement and a numb little finger means the ulnar nerve |
| Lateral condyle (child) | Growth disturbance | Late cubitus valgus and tardy ulnar palsy |
Radius and ulna
| Injury | Bone broken | Joint dislocated | Note |
|---|---|---|---|
| Monteggia | Proximal ulna | Radial head (proximal radioulnar joint) | Posterior interosseous nerve at risk |
| Galeazzi | Distal radial shaft | Distal radioulnar joint | Ulnar head prominent at the wrist |
| Colles | Distal radius | None; distal fragment displaced dorsally | "Dinner fork"; osteoporotic women |
| Smith | Distal radius | Distal fragment displaced volarly | Fall on flexed wrist |
| Radial head | Radial head | None | Fall on outstretched hand; elbow effusion |
- A forearm bone cannot break and shorten without the other bone breaking or a radioulnar joint dislocating, because the two form a ring. So always X-ray the elbow and wrist.
- The interosseous membrane fibres run downwards and medially from radius to ulna, transmitting force from the hand (which articulates with the radius) to the ulna and humerus.
- Both Monteggia and Galeazzi injuries need open reduction and fixation in adults.
Carpus and hand
- Proximal row lateral to medial: scaphoid, lunate (the middle bone), triquetrum, pisiform. Distal row: trapezium, trapezoid, capitate, hamate. Capitate is the largest carpal bone.
- Scaphoid: commonest carpal fracture; snuffbox tenderness; first X-ray can be normal; blood enters distally, so the proximal pole undergoes avascular necrosis.
- Lunate: commonest carpal dislocation, into the carpal tunnel (median nerve); Kienböck disease is avascular necrosis of the lunate.
- Hook of hamate fracture (golf, racquet sports): ulnar nerve in Guyon's canal.
- Boxer's fracture: neck of the fifth metacarpal. Bennett fracture: intra-articular fracture-dislocation of the base of the first metacarpal, unstable because abductor pollicis longus pulls the shaft proximally. Rolando fracture is the comminuted version.
Remember Every fracture question is three facts: the mechanism, the deformity, and the structure lying against the bone.
Children and healing
- Greenstick and buckle (torus) fractures occur because children's bone is soft and has a thick periosteum.
- Growth plate injuries are graded by Salter–Harris: type I through the plate, type II through the plate and metaphysis (commonest), III through the plate and epiphysis, IV across all three, V crush. Types III to V risk growth arrest.
- Healing stages: haematoma, inflammation, soft callus, hard callus, remodelling.
- Complications: compartment syndrome, nerve and vessel injury, malunion (cubitus varus after supracondylar fracture), non-union (scaphoid), avascular necrosis, complex regional pain syndrome, myositis ossificans around the elbow.
Exam trap Monteggia breaks the ulna and dislocates the radial head; Galeazzi breaks the radius and dislocates the distal radioulnar joint.
Exam trap A normal first X-ray does not exclude a scaphoid fracture; treat clinically and re-image.
How FCPS asks about this
- Midshaft humeral fracture with wrist drop but intact elbow extension: radial nerve in the spiral groove; triceps branches arise higher.
- Surgical neck fracture: axillary nerve and posterior circumflex humeral artery.
- Recurrent anterior dislocation in a young man: Bankart lesion; head escapes anteroinferiorly where the capsule lacks cuff support.
- Lateral clavicle riding over the acromion: AC separation; coracoclavicular ligament torn in severe cases. Commonest clavicle fracture site: middle third.
- Inferior tibiofibular joint type: syndesmosis; the first carpometacarpal joint is a saddle joint.
- Monteggia versus Galeazzi: ulna plus radial head; radius plus distal radioulnar joint.
- Middle bone of the proximal carpal row that dislocates: lunate, compressing the median nerve.
Test yourself on this topic
5 of the 12 questions in our bank on this topic. Choose an answer to see why every option is right or wrong.
An elderly woman falls on her outstretched hand. The wrist has a 'dinner fork' deformity, and X-ray shows a distal radius fracture within 2.5 cm of the wrist. Which displacement is typical?
Answer: Dorsal displacement (Colles)
A Colles fracture is a distal radius fracture from a fall on the outstretched hand, typical of postmenopausal osteoporotic women: the distal fragment is displaced and angulated dorsally (and radially) with impaction, producing the dinner-fork deformity. A Smith fracture (reverse Colles), from a fall on the flexed wrist, has volar displacement (garden spade deformity). Complications: malunion, median nerve compression, delayed rupture of extensor pollicis longus, complex regional pain syndrome and stiffness. A fragility fracture should prompt osteoporosis assessment. Monteggia is an ulnar shaft fracture with radial head dislocation; Galeazzi a radial shaft fracture with distal radioulnar dislocation.
Distal radius fractures
- Colles: dorsal displacement, dinner fork; elderly, osteoporosis
- Smith: volar displacement (reverse Colles)
- Complications: malunion, median nerve, EPL rupture, CRPS
- Check for osteoporosis
Remember Colles goes to the back; Smith slips to the front.
Why the other options are wrong
- Volar displacement (Smith) Smith fracture.
- Ulna with radial head dislocation Monteggia.
- Scaphoid waist fracture Snuffbox tenderness; different injury.
- Radius with DRUJ dislocation Galeazzi.
A 19-year-old wrestler has had three anterior shoulder dislocations in a year, each with less force. Which of the following best explains the recurrence?
Answer: Detached anteroinferior labrum (Bankart)
In an anterior dislocation the humeral head is forced forwards and downwards, stripping the anteroinferior labrum together with the attached inferior glenohumeral ligament from the glenoid rim (Bankart lesion). This removes the labral bumper and the main anterior restraint in abduction and external rotation, so the shoulder redislocates with less and less force. Young, active patients have the highest recurrence rates. Cuff tears are more typical after dislocation in patients over about 40.
Bankart lesion
- Anteroinferior labrum and IGHL torn off the rim
- Loss of the main anterior restraint
- Young athletes: high recurrence
- Hill–Sachs: the matching head defect
Remember Recurrent anterior dislocation in the young: Bankart lesion.
Exam trap Over 40, persistent weakness after dislocation is more often a cuff tear than an axillary nerve palsy.
Why the other options are wrong
- Rupture of the long head of biceps Gives a distal bulge in the arm, not instability.
- Supraspinatus tendon tear More typical after dislocation in older patients.
- Axillary nerve palsy Causes deltoid weakness and numbness, not recurrence.
- Tear of the coracoclavicular ligament An acromioclavicular injury, not glenohumeral.
Two years after a supracondylar fracture, a 9-year-old girl has a 'gunstock' elbow angled towards the midline. Which of the following explains this?
Answer: Malunion: distal fragment tilted medially
Cubitus varus (gunstock deformity) is the commonest late complication of a supracondylar fracture. It results from malunion, with the distal fragment tilted into varus and internally rotated, rather than from damage to the growth plate, which is why it does not correct with growth. Function is usually good and the problem is mainly cosmetic; corrective osteotomy can be done. Nonunion of a lateral condyle fracture produces the opposite, cubitus valgus, which can later stretch the ulnar nerve. Ischaemic contracture affects the forearm and fingers, not the carrying angle.
Cubitus varus
- Late result of supracondylar fracture
- Due to malunion, not growth arrest
- Does not remodel with growth
- Mainly cosmetic
Remember Gunstock elbow: malunited supracondylar fracture.
Exam trap Children's fractures remodel well in the plane of joint movement, but not angulation in the coronal plane or rotation.
Why the other options are wrong
- Arrest of the distal humeral growth plate Growth arrest is not the cause, which is why the deformity persists unchanged.
- Nonunion of a lateral condyle fracture Gives cubitus valgus, the opposite deformity.
- Fibrosis of ischaemic forearm flexors Volkmann contracture causes finger and wrist flexion deformity.
- Chronic dislocation of the radial head Does not change the carrying angle in this way.
A 30-year-old labourer falls while gripping a beam overhead. He arrives holding his arm fully abducted above his head, cannot lower it, and the humeral head can be felt in the axilla. What is the diagnosis?
Answer: Inferior dislocation (luxatio erecta)
Luxatio erecta is an inferior dislocation of the shoulder caused by forced hyperabduction, which levers the humeral neck against the acromion and drives the head out through the inferior capsule. The arm is locked in abduction above the head, with the head lying below the glenoid and the shaft pointing upwards. Because the head sits in the axilla, the axillary nerve and axillary artery are at particular risk and must be checked before and after reduction. Rotator cuff tears and greater tuberosity fractures are common.
Luxatio erecta
- Forced hyperabduction
- Arm locked overhead
- Head below the glenoid
- Check axillary nerve and artery
Remember Arm stuck above the head: inferior dislocation.
Exam trap Neurovascular injury is common in luxatio erecta, so document pulses and sensation before attempting reduction.
Why the other options are wrong
- Anterior subcoracoid dislocation The arm is held slightly abducted and externally rotated, not locked above the head.
- Posterior dislocation The arm is held adducted and internally rotated, typically after a seizure.
- Acromioclavicular dislocation The clavicle rides up at the acromioclavicular joint; the glenohumeral joint is normal.
- Fracture of the surgical neck The arm hangs at the side; it is not locked overhead.
The inferior tibiofibular joint, where the bones are held together by a strong interosseous ligament, is an example of which joint type?
Answer: Syndesmosis
A syndesmosis is a fibrous joint in which bones are united by a ligament or interosseous membrane, allowing slight movement. Examples are the inferior tibiofibular joint and the interosseous membranes of the forearm and leg. A suture is a fibrous joint between skull bones, and a gomphosis anchors a tooth in its socket. Synchondroses are primary cartilaginous joints (epiphyseal plates), and symphyses are secondary cartilaginous joints in the midline (pubic symphysis, intervertebral discs).
Joint types
- Fibrous: suture, gomphosis, syndesmosis
- Syndesmosis: inferior tibiofibular, interosseous membranes
- Primary cartilaginous: synchondrosis
- Secondary cartilaginous: symphysis (midline)
Remember Bones tied by a ligament: syndesmosis.
Exam trap High ankle sprains injure this syndesmosis.
Why the other options are wrong
- Symphysis A symphysis is fibrocartilaginous and midline.
- Synchondrosis A synchondrosis is hyaline cartilage, such as a growth plate.
- Gomphosis A gomphosis is a tooth in its socket.
- Suture Sutures join skull bones.
Where this sits in the CPSP syllabus
- Paper 1: Upper limb, Upper limb bones, joints and fractures
- Surgery & Allied, Paper 2: Upper limb, Upper limb bones, joints and fractures