Distal Radius — Colles/Smith/Barton

Distal radius fractures are the most common fractures seen in the emergency department, accounting for approximately 17% of all fractures. They affect two distinct populations: young adults sustaining high-energy trauma, and elderly patients (predominantly post-menopausal women) sustaining low-energy falls — the latter representing an osteoporotic fragility fracture. The eponymous fractures — Colles`, Smith`s, and Barton`s — describe specific fracture patterns based on the mechanism and displacement, each with distinct clinical and radiological features and management implications.

• Epidemiology: bimodal age distribution — young adults (high energy) and elderly women (osteoporotic low-energy fall); approximately 500,000 distal radius fractures per year in the USA; one of the sentinel fragility fractures (a distal radius fracture in a woman over 50 should prompt DEXA and osteoporosis treatment — it predicts a 1.5–3× increased risk of subsequent hip fracture)
• Anatomy of the distal radius: the distal articular surface of the radius has three key parameters — (1) radial inclination: the angle of the radial articular surface in the coronal plane, normally 22–23° (tilted ulnarward); (2) palmar tilt (volar tilt): the angle of the articular surface in the sagittal plane, normally 11–12° (tilted volarly); (3) radial height (radial length): the longitudinal distance between the tip of the radial styloid and the level of the ulnar head, normally 11–12 mm; these three parameters define radiological reduction goals; loss of these parameters correlates with functional outcome
• The DRUJ (distal radio-ulnar joint): the DRUJ is destabilised in many distal radius fractures (particularly those with ulnar styloid fractures at the base, TFCC tears, or significant radial shortening); DRUJ instability leads to forearm rotation restriction and ulnar-sided wrist pain; assessment of DRUJ stability after fracture reduction is essential

• Frykman classification: an 8-type classification based on (1) extra-articular vs intra-articular involvement of the radiocarpal joint and DRUJ; (2) presence or absence of associated ulnar styloid fracture; Types I–IV are without ulnar styloid fracture; Types V–VIII are the same patterns with concurrent ulnar styloid fracture; higher Frykman types are associated with greater instability and worse prognosis; Type VIII (intra-articular radiocarpal + DRUJ involvement + ulnar styloid fracture) is the most complex; the Frykman classification is commonly used in the UK and in exams
• AO/OTA classification: A (extra-articular), B (partial articular), C (complete articular — the most clinically relevant distinction); C3 fractures (complete articular, multifragmentary — highly comminuted intra-articular fractures) are the most challenging to manage and most commonly require surgical fixation; used in research and for surgical planning

• Acceptable radiological parameters post-reduction (British Orthopaedic Association/BSSH guidelines): radial shortening <3 mm (ulnar variance ≤ neutral); dorsal tilt <10° (ideally restore volar tilt); radial inclination >15°; intra-articular step or gap <2 mm; these are the thresholds beyond which surgical fixation is considered; loss of radial height (>3 mm shortening) is associated with DRUJ instability and poor functional outcomes
• Radiographic measurements: (1) radial inclination — angle between a line perpendicular to the radial shaft and a line along the radial articular surface on AP view; normal 22–23°; (2) volar tilt — angle of the articular surface on lateral view relative to the radial shaft axis; normal 11–12° volar; (3) radial height — distance from radial styloid tip to the ulnar head level on AP view; normal 11–12 mm; (4) ulnar variance — the relative lengths of the radius and ulna at the DRUJ; neutral (equal) is normal; positive ulnar variance (ulna longer than radius) results from radial shortening and leads to ulnar impaction syndrome

• Acute management: analgesia; haematoma block (local anaesthetic injected into the fracture haematoma) or Bier`s block (IV regional anaesthesia); manipulation under anaesthesia (MUA) to restore acceptable alignment; application of a below-elbow plaster backslab (not a full cast — allows for swelling); elevation; check X-rays post-manipulation
• Conservative management: stable, adequately reduced fractures in elderly low-demand patients; immobilisation in a below-elbow cast for 5–6 weeks; close radiological follow-up at 1 week (fractures frequently re-displace within the first week); if the fracture re-displaces beyond acceptable parameters on the 1-week X-ray, re-manipulation or surgical fixation is required; re-manipulation after 2 weeks is rarely effective (early callus formation prevents adequate reduction)
• Volar locking plate (VLP) ORIF: the most common surgical fixation method; a low-profile titanium plate is applied to the volar surface of the distal radius through a flexor carpi radialis (FCR) approach; locking screws purchase the subchondral bone of the distal radius from the volar side, providing stable fixation of dorsal comminution; advantages — allows early mobilisation, excellent maintenance of reduction, suitable for intra-articular fractures; the `watershed line` is the distal ridge of the pronator fossa on the volar radius — the plate must not protrude distal to the watershed line or flexor tendon irritation/rupture (FPL most commonly) will result
• Surgical indications: failure to achieve or maintain acceptable reduction; unstable fracture patterns (intra-articular displacement >2 mm, dorsal comminution, high-energy mechanism, patient age <60 with high functional demands); Smith`s fracture; Barton`s fracture-dislocation; open fracture; associated carpal injury; neurovascular compromise
• Bridging external fixator: used for highly comminuted fractures where internal fixation is not possible; uses ligamentotaxis (distraction across the fracture through the carpal ligaments) to restore length; largely superseded by VLP for most fractures in centres with expertise but still useful for grossly contaminated open fractures or as a temporary measure

• Carpal tunnel syndrome: median nerve compression from haematoma, swelling, or displaced fracture fragments; presents with acute paraesthesia in the median nerve distribution after distal radius fracture; requires urgent carpal tunnel decompression if acute CTS develops; CTS is the most common acute neurological complication of distal radius fractures
• Malunion: the most common complication; dorsal malunion causes loss of grip strength, wrist stiffness, and mid-carpal instability; significant malunion (dorsal tilt >20°, radial shortening >5 mm, intra-articular step >2 mm) may require corrective osteotomy (opening wedge radial osteotomy)
• DRUJ instability: results from radial shortening and TFCC disruption; causes forearm rotation restriction and ulnar-sided pain; managed with TFCC repair or DRUJ stabilisation if persistent after fracture healing
• Flexor tendon rupture (FPL): complication of volar locking plate prominence distal to the watershed line; the FPL tendon ruptures over the proud plate; prevented by meticulous plate positioning; treated with tendon transfer (EIP to FPL) or tenodesis
• Extensor pollicis longus (EPL) rupture: occurs in undisplaced or minimally displaced distal radius fractures (not severe fractures); the EPL ruptures within its groove at Lister`s tubercle due to friction as it passes over the prominent tubercle or due to disruption of its mesotenon from the fracture haematoma; presents with inability to extend the thumb IP joint several weeks after the fracture; treated with EIP-to-EPL tendon transfer
• CRPS Type I (Sudeck`s atrophy): disproportionate pain, stiffness, autonomic changes; more common in elderly women; management — pain management, physiotherapy, sympathetic nerve blocks; prevention — adequate analgesia, early mobilisation

• Colles`: FOOSH extended wrist; dorsal displacement; `dinner fork` deformity; most common distal radius fracture (~90%); Smith`s: FOOSH flexed wrist; volar displacement; `garden spade` deformity; frequently needs VLP
• Barton`s: intra-articular fracture-dislocation; shear mechanism; carpus subluxes with the fracture fragment; inherently unstable; requires ORIF
• Acceptable reduction: radial shortening <3 mm; dorsal tilt <10°; radial inclination >15°; intra-articular step/gap <2 mm; check at 1 week — frequent re-displacement
• Normal radiological parameters: volar tilt 11–12°; radial inclination 22–23°; radial height 11–12 mm; positive ulnar variance = radial shortening = DRUJ instability + ulnar impaction
• VLP ORIF: FCR approach; locking screws through volar plate fix dorsal comminution; `watershed line` = distal limit of plate — plate DISTAL to watershed = FPL rupture risk; most common surgical technique
• Frykman classification: Types I–VIII; extra-articular to intra-articular DRUJ; with/without ulnar styloid fracture; higher number = more complex; Type VIII = worst
• EPL rupture: undisplaced fractures; friction at Lister`s tubercle; weeks after injury; EIP-to-EPL transfer treatment
• Acute CTS: most common acute neurological complication; urgent decompression if acute paraesthesias in median nerve distribution post-fracture
• Distal radius fracture = fragility fracture sentinel: in women >50, mandates DEXA + osteoporosis treatment; predicts 1.5–3× increased hip fracture risk
• DRUJ: assess stability after every distal radius fracture reduction; base of ulnar styloid fracture + TFCC tear = DRUJ instability; forearm rotation restriction + ulnar pain = DRUJ problem