Isolated Radius Fractures

An isolated radius fracture is a fracture of the radial shaft without involvement of the distal radioulnar joint (DRUJ) or the proximal radioulnar joint (PRUJ). It is less common than the both-bone forearm fracture, and it is a diagnosis made only after two look-alikes have been excluded: the Galeazzi injury (distal third of the radius with DRUJ disruption) and the Monteggia injury (proximal ulna with the radial head dislocated).

Mechanism. A direct blow or high-energy trauma. A direct defensive blow is the mechanism of the nightstick fracture, but that name belongs to the isolated fracture of the ulnar shaft (see the differential below), not to the radius.

Who. It is common in young active men after trauma and occurs occasionally in elderly patients after falls. High-energy injuries such as motor vehicle accidents have a high association with compartment syndrome.

A load-sharing ring. The radius and ulna form a ring, joined by the proximal and distal radioulnar joints and the interosseous membrane (IOM). The radius transmits 80% of the axial load from the wrist. If the IOM is disrupted (Essex-Lopresti), the radius migrates proximally, causing ulnocarpal impaction and elbow dysfunction.

The interosseous membrane. Its central band is the primary longitudinal stabiliser of the forearm. The fibres run obliquely from the radius proximally to the ulna distally, transferring load from the radius (wrist) to the ulna (elbow), and a fracture of the radius disrupts that transfer.

The radial bow. The radius rotates around the straight ulna like a bucket handle, pronation and supination turning about an axis that passes through the radial head and the ulnar head. The radius has a lateral bow with its apex at the level of the pronator teres insertion, and the maximum bow is typically 15 mm from the straight line connecting the tuberosity to the styloid.

Why the bow matters. Lose the bow and you lose the sweep: the radius impinges on the ulna and pronation and supination are lost. Any angulation acts as a cam that blocks rotation, and 10 degrees of angulation can block 50% of it. This is why anatomic reduction is critical.

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Deforming forces. Biceps (a supinator) and pronator teres (a pronator) pull the fragments into a deformity that depends on the level of the fracture; pronator teres pronates and flexes the middle fragment, and pronator quadratus pronates the distal one. In the proximal third the forearm is plated in supination to match the proximal fragment; the table gives the position for each level.

Blood supply. The nutrient artery enters the radius in the proximal third from the anterior interosseous artery. Fractures distal to it may heal more slowly, their supply arriving by retrograde flow.

Shape and plating surfaces. The shaft is triangular in cross-section, with anterior, posterior and interosseous borders. The volar surface is flat and ideal for plating, and LCDCP plates sit well on it; the dorsal surface is convex and covered by the extensor muscles, so a plate there is prominent. The safe zone for implants is the flat volar surface in the distal two-thirds and the dorsal surface in the proximal third.

Nerves at risk. The anterior interosseous nerve has a section of its own below. The others:

• Superficial radial nerve - lies under brachioradialis, at risk in the Henry approach
• Posterior interosseous nerve (PIN) - pierces supinator, at risk in any proximal exposure, Henry or Thompson
• Median nerve - medial to FCR, at risk in the Henry approach

AO/OTA. The forearm bones are coded 22, and the pattern guides fixation: a type A fracture can achieve absolute stability with compression plating, while a type C fracture requires bridge plating.

• 22-A - simple (transverse or oblique): A1 ulna alone, A2 radius alone (this topic), A3 both bones
• 22-B - wedge (butterfly fragment)
• 22-C - multifragmentary (comminuted)

By level. Location determines the deforming forces (see Anatomy) and the surgical approach, and is clinically useful for preoperative planning:

• Proximal third - supination deformity; the hardest to access, with the PIN at risk, and requires careful nerve protection during exposure
• Middle third - neutral deformity at the apex of the bow; the most common location for an isolated radius fracture
• Distal third - pronation deformity and the Galeazzi risk; always assess DRUJ stability

History. Establish the mechanism, a direct blow or a fall on the outstretched hand, and look for a defensive wound.

Examination. Note angulation and rotational deformity, then the soft tissues: open wounds, tented skin, a tight compartment. Forearm compartment syndrome is a surgical emergency, announced by pain on passive finger extension (Volkmann's ischaemia). Each nerve has its own motor test:

• PIN - thumbs up (EPL) and finger extension (EDC); wrist extension is preserved (ECRL)
• AIN - the OK sign (FPL and FDP); AIN palsy is common with proximal-third fractures
• Ulnar nerve - crossing the fingers (interossei)

The hidden Galeazzi. If the radius is shortened by more than 5 mm, the DRUJ must be injured: an "isolated" radius fracture with significant shortening is a Galeazzi. The table sets out how each mimic declares itself.

Soft-tissue grading. The Tscherne classification grades the soft-tissue injury:

• Grade 0 - minimal soft-tissue damage
• Grade 1 - superficial abrasion or contusion
• Grade 2 - deep contaminated abrasion with local skin or muscle contusion
• Grade 3 - extensive skin contusion or crushing, muscle destruction, compartment syndrome

Radiographs. Image the whole forearm and the joints at both ends:

• Forearm AP and lateral - elbow and wrist on one film if possible, or separate films
• Wrist AP and lateral - ulnar variance (shortening) and DRUJ widening
• Elbow AP and lateral - the radial head (Monteggia)

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CT is not routine for a simple shaft fracture. It is protocolled as 1 mm slices with 3D reconstructions, and is indicated for:

• Articular extension (an intra-articular fracture)
• Suspected pathological fracture (a lytic lesion)
• Planning complex comminution (butterfly fragments)
• End-segment fractures, very proximal or very distal, to check for joint involvement

MRI is indicated when DRUJ instability is suspected but the radiographs are equivocal. It is sensitive for central or peripheral tears of the triangular fibrocartilage complex (TFCC), and FSE or STIR sequences can visualise the central band of the IOM.

Ultrasound is useful for assessing the continuity of the PIN when a palsy is present, and can assess the integrity of the IOM dynamically.

The decision. Three things decide treatment: displacement, fracture pattern and associated injuries. Galeazzi and Monteggia patterns are always ruled out before the fracture is treated as isolated. The goal is anatomic reduction with stable fixation, to allow early motion and prevent complications.

Displacement. An undisplaced fracture (less than 2 mm) may be managed in a cast with weekly monitoring; a fracture displaced more than 2 mm requires surgical fixation. As working limits, angulation greater than 5 degrees is unacceptable and 50% contact is the minimum for stability, though how much a load-sharing radius can tolerate is debated (see Controversies).

Special circumstances. Four situations change the plan:

• Open fractures - immediate antibiotics and I&D, with immediate plating if the wound is clean
• Segmental fractures - consider a staged approach (see the section on segmental fractures and bone loss)
• Bone loss - a staged Masquelet technique may be required
• Pathological fractures - biopsy first, then fix; oncologic principles take precedence

The DRUJ. Distal-third fractures are the group in which the joint matters. In Rettig and Raskin's Galeazzi series, fractures within 7.5 cm of the midarticular surface of the distal radius had residual DRUJ instability after anatomic radial fixation in 12 of 22 (55%), against 1 of 18 (6%) for fractures more than 7.5 cm away. Measure the distance on the preoperative film, and test the joint after fixation whatever the answer, one last time before leaving theatre (DOI).

Who is treated in a cast. Non-operative management is rarely appropriate for an adult isolated radius fracture. The indication is an isolated, undisplaced (less than 2 mm), rotationally neutral fracture, which is very rare in adults and better suited to paediatric patients. In an adult it should only be considered in a very low-demand elderly patient with minimal displacement; most adult isolated radius fractures will displace and require surgical fixation.

The cast. A long arm cast, with the forearm rotated to suit the level of the fracture (see the deforming-forces table in Anatomy). Radiograph weekly for 4 weeks to watch for displacement.

The risk of displacement. Displacement is a real risk even when the fracture is undisplaced at first, and no cited series quantifies it. The protection is the weekly radiograph and a low threshold to convert to ORIF if any displacement occurs, not a quoted percentage.

Choosing the approach. Proximal-third fractures can be approached dorsally (Thompson) or volarly (Henry), and both require protection of the PIN. For middle- and distal-third fractures the volar Henry approach is preferred.

Volar Approach (Henry)Dorsal Approach (Thompson)Fixation Principles

The workhorse. The Henry approach is safe for the whole radius. The incision follows a line from the biceps tendon to the radial styloid, and the superficial interval lies between brachioradialis (radial nerve) and FCR (median nerve).

Deep dissection, proximally. Step by step:

1. Find the radial recurrent vessels, the leash of Henry: a fan of arteries and veins crossing the field from medial to lateral just distal to the elbow. Ligate or cauterise them individually.
2. Once the leash is divided, the supinator muscle fibres can be seen wrapping around the proximal radius.
3. Supinate the forearm fully. The PIN runs within supinator, and supination moves it laterally, away from the incision.
4. Incise the supinator insertion on the anterior aspect of the radius, down to bone.
5. Elevate the muscle laterally without vigorous retraction; the PIN is protected within the muscle belly.
6. This exposes the proximal third of the radius.

Mnemonic

SPINPIN Protection

S

Supinate

Fully supinate the forearm to move PIN laterally.

P

Protect

PIN runs within Supinator muscle belly.

I

Incise

Incise Supinator on anterior radius surface only.

N

No retraction

Gentle elevation, no vigorous retraction.

Hook:SPIN the forearm to protect the PIN - supination saves the nerve!

When the exposure is tight. Distally, partially releasing the brachioradialis tendon allows much greater retraction. Proximally, the radius cannot be seen without full supination; if supination is blocked, look for an interposed fragment or incomplete soft-tissue release.

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When to use it. The Thompson approach is useful for very proximal fractures where the Henry approach may be limited, and is reserved for cases in which proximal exposure is critical and Henry cannot provide adequate visualisation. The incision runs on a line from the lateral epicondyle to Lister's tubercle, following the interval between the extensor compartments.

The interval and the nerve. The internervous plane lies between ECRB (radial nerve) and EDC (PIN). The PIN is found emerging from the distal border of supinator and must be identified and protected.

Its limits. The exposure is limited to the proximal third of the radius, and the plate goes on dorsally, where thin skin makes soft-tissue cover harder. The disadvantages that follow:

• Less soft-tissue coverage
• Risk of extensor tendon irritation
• More difficult to extend distally

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The implant. A 3.5 mm plate is standard: LCDCP or LCP. Compression plating is preferred for simple transverse fractures, and locking is reserved for osteoporotic bone or comminution (bridge mode). A 7- or 8-hole plate is typical, longer for comminuted fractures. Stainless steel (316L) or titanium (Ti-6Al-4V) may be used; stainless steel is stiffer and cheaper.

Contour the plate to the bone. The radius is not straight: it has a proximal bend and a distal bow. Pre-contoured plates are available, but manual contouring is often needed to match the bow. The volar surface is the tension side for the distal radius, but a straight plate on a curved bone will straighten it as the screws are tightened, and the bow is lost.

Compression. For simple transverse or short oblique fractures, over-bend the plate to compress the far cortex (eccentric compression); this achieves primary bone healing without callus. An oblique fracture takes an interfragmentary lag screw, through or outside the plate, perpendicular to the fracture line.

Screws. A minimum of 3 bicortical screws (6 cortices) each side of the fracture, more in osteoporotic bone or comminution. From the Synthes LCP small fragment set:

• 3.5 mm cortical screws (gold) - for compression or lagging; 2.5 mm drill bit
• 3.5 mm locking screws (green) - for osteopenic bone or bridge plating; 2.8 mm drill bit

Screw length and torque. Do not over-torque screws in the forearm: the bone is hard but narrow. Intra-articular screws in the DRUJ or PRUJ are disastrous, and shaft screws that are too long will irritate the dorsal tendons (EPL). Measure twice.

Reduction manoeuvres. Four tools for the deep wound:

• Toggle - insert a screw into one fragment, leave it loose, and use the plate as a lever to toggle the reduction
• Traction - by an assistant; finger traps are unnecessary for a shaft fracture, and manual traction is fine
• Rotation - match the fragments; the interosseous border should be a sharp line, and if it is dull or jagged the reduction is rotated
• Clamps - pointed reduction clamps (Weber) are useful but hard to place deeply; verbal reduction (traction, rotate) is safer than aggressive clamping in a deep wound

Preserve the biology. Strip only the periosteum that lies under the plate, and keep the soft-tissue attachments elsewhere to maintain the blood supply.

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Compartment syndrome. The forearm is the second most common site for compartment syndrome after the leg. Bleeding into the volar (flexor) or dorsal (extensor) compartments raises the pressure, and the volar compartment is the most critical because it contains the median and ulnar nerves and the flexor muscles. Perfusion pressure is diastolic blood pressure minus compartment pressure; below 30 mmHg, muscle ischaemia begins.

The six Ps. Not all of them are worth the same:

• Pain out of proportion to the injury, breaking through analgesia
• Pain on passive stretch - the earliest and most sensitive sign; extending the fingers stretches the flexors
• Paraesthesia - a late sign
• Paralysis - a late sign (ischaemia)
• Pulselessness - a very late sign (arterial shutoff)
• Pallor - unreliable

Fasciotomy. Treatment is urgent fasciotomy. The volar release is a Henry approach extended from elbow to wrist, S-shaped across the crease, releasing the lacertus fibrosus, the carpal tunnel and the volar fascia; the dorsal release is a straight dorsal incision. Its sequel is Volkmann's ischaemic contracture: a clawed hand, sensory loss and a useless limb.

Radioulnar synostosis. A bone bridge between radius and ulna causes total loss of rotation. The risk factors are a single incision for both bones, a breach of the interosseous membrane, head injury and bone graft. Prevent it with separate incisions and by not dissecting deep into the IOM.

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Refracture and plate removal. Refracture after plate removal is the reason not to remove a forearm plate routinely: the forearm is a load-sharing bone, and removing the plate leaves stress risers. Be careful with the figure quoted, though. The paediatric series in the evidence below describes refracture with the implant still in place, clustered at the plate ends, not after removal, and no study cited here measures the risk of removal itself. Remove only symptomatic hardware, after solid union and not before 18-24 months, and counsel that the risk is real but unquantified.

Nerve palsy. PIN palsy (loss of finger extension) is usually a neuropraxia from retraction. Observe for 3 months, with an EMG at 6 weeks if there is no recovery, and consider tendon transfers (Jones transfer) if the palsy is permanent. The AIN is covered in its own section below.

Nonunion. Uncommon after compression plating: the Anderson series in the evidence below united 97.9% of radii. The risk rises with infection, inadequate fixation, bone loss and smoking. An atrophic nonunion requires bone graft and compression.

Elbow instability. This is a missed Monteggia lesion. Always check the elbow.

Implant irritation. Dorsal plates often irritate the extensor tendons (EPL, EDC), and volar plates can irritate FPL, so check the screw lengths. Removal is indicated if the plate is symptomatic after union.

Complex regional pain syndrome. Characterised by allodynia, swelling and colour changes. Prevention rests on vitamin C, early motion and pain control.

Weeks 0-2: the wound. A posterior slab or removable splint, and elevation, which is critical to reduce swelling and compartment pressure. Active finger motion starts immediately to prevent tendon adhesions and oedema; typing is allowed straight away because the fingers are free.

Weeks 2-6: motion. Sutures come out at 10-14 days. Active elbow flexion and extension begin, and so do supination and pronation, which are often the hardest to regain; practise rotation with the elbow at 90 degrees, which isolates the forearm, and at 0 degrees. No heavy lifting: a cup of coffee only.

Weeks 6-12: strength. Radiographs look for signs of union (callus, bridging), and progressive resistance exercises begin if union is evident. Light duties resume at 6-8 weeks, and driving at about 6 weeks, once out of the splint and able to grip and turn the wheel comfortably.

Months 3-6: return. Manual labour at 3-4 months. Push-ups, an axial load, are not allowed until 3 months. Contact sport is allowed when cortical bridging is seen on 3 of 4 cortices, at 3-6 months depending on the level of contact.

Rotation. Lost pronation is tolerated better than lost supination: shoulder abduction can compensate for pronation, but nothing compensates well for supination.

Oedema and stiffness. Persistent oedema leads to fibrosis of the IOM and stiffness, so early oedema management should be aggressive. If stiffness persists at 6 weeks, dynamic splinting may be required, such as a turnbuckle splint for supination.

The rest of the programme. Four further measures:

• Scar - the Henry scar can be sensitive; desensitisation massage starts at 3 weeks
• Contrast baths - heat and cold to maximise vascular flow and reduce swelling
• Functional tasks - turning doorknobs, using screwdrivers, pouring water
• Proprioception - a gyroscope ball or wobble board for wrist stability late in rehabilitation

Union. Compression plating achieves a union rate greater than 95% with absolute stability, and bridge plating of comminuted fractures gives comparable rates of 90-95%.

Function. Most patients lose 10-20 degrees of rotation compared with the normal side, but the functional loss is minimal. Grip strength usually returns to 90% of normal by 6-12 months, and satisfaction with surgical treatment is high.

The long term. Arthritis is a rare late complication, usually related to malunion or joint injury, and persistent stiffness is uncommon with proper rehabilitation. Good outcomes are associated with anatomic reduction, restoration of the radial bow, stable fixation allowing early motion and the absence of complications; poor outcomes with malunion, nonunion, compartment syndrome and nerve injury.

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Anatomy. The AIN is the largest motor branch of the median nerve. It arises in the proximal forearm, approximately 5-8 cm distal to the lateral epicondyle, as the median nerve passes between the two heads of pronator teres, then runs distally on the volar surface of the interosseous membrane between FPL laterally and FDP medially, ending in pronator quadratus. It supplies FPL, FDP to the index (and often the middle) finger, and pronator quadratus, and carries no cutaneous sensation, only deep proprioceptive and joint fibres.

Why it is at risk. Proximal-third radial shaft fractures and the deep volar (Henry) dissection put the AIN at risk from the fracture fragment, haematoma or retraction. Because it lies on the interosseous membrane against the radius, it is vulnerable where the exposure is most proximal.

The abnormal pinch. Without thumb interphalangeal flexion (FPL) and index distal interphalangeal flexion (FDP), the patient cannot form a round tip-to-tip "O"; the pinch collapses into a flat pulp-to-pulp, "square" or "triangle" pinch, which is the pinch-grip or OK-sign test. Pronator quadratus weakness is unmasked by resisted pronation with the elbow fully flexed, which eliminates pronator teres. Sensation is entirely normal, and that is what distinguishes the lesion from a high median nerve palsy.

Management. Most post-traumatic and postoperative AIN palsies are neuropraxia from traction or retraction and recover spontaneously, usually within about 3-6 months, so observe with serial examination. The steps:

• First exclude a mechanical cause of a failed OK sign: FPL or FDP tendon rupture (check the tenodesis effect and look for a laceration at the wrist) and attritional tendon injury from prominent volar hardware
• If there is no recovery, obtain nerve conduction studies and EMG at about 6-12 weeks
• Explore only if the nerve is entrapped by a fragment or implant, or may have been divided

Spontaneous, non-traumatic AIN neuropathy carries the eponym Kiloh-Nevin syndrome.

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Why these fractures behave badly. Segmental patterns, two fracture lines isolating an intercalary segment, and any cortical or critical-sized defect follow a high-energy mechanism, with periosteal stripping and a devascularised middle segment. They carry the highest rates of compartment syndrome, delayed union and nonunion. In Nappo et al's high-energy open forearm series, segmental bone loss carried a relative risk of nonunion of 6.2 and deep infection a relative risk of 9.9, the two dominant nonunion drivers.

Fixation. Length and rotation are hard to judge when a segment is missing, so template against the contralateral normal radius and reproduce the magnitude and location of the radial bow (Schemitsch). Use a long bridge plate spanning both fracture levels (relative stability), and deliberately preserve the soft-tissue attachments of the intercalary segment rather than stripping it bare.

Managing the defect. A staged decision that depends on size:

• Small contained defects - stable fixation plus primary autogenous cancellous graft (iliac crest) usually unites
• Larger segmental defects (greater than a few centimetres) - the induced-membrane (Masquelet) technique: stage one places an antibiotic cement spacer to form a vascular biomembrane and hold length and alignment; stage two, at about 6-8 weeks, removes the spacer and packs cancellous autograft into the preserved membrane
• Very large or infected defects - a vascularised graft (free fibula) provides living bone that hypertrophies and tolerates a poor bed
• Deep infection - debride and stage, and do not graft into contaminated tissue, reflecting the relative risk of 9.9 for infection-associated nonunion

Global Epidemiology:

• Isolated radial shaft fractures are uncommon relative to both-bone forearm and distal radius fractures, occurring in a bimodal distribution: high-energy trauma in young men (road traffic and sporting injuries) and lower-energy falls in older adults.
• High-energy mechanisms carry a disproportionate burden of compartment syndrome, open injury, and associated DRUJ disruption (the "occult Galeazzi").

Side-by-Side Guideline Principles:

Plate or intramedullary nail. Anatomic plating is the established standard for the adult radial shaft, but newer locked forearm nails claim comparable union with less soft-tissue stripping. High-quality comparative data on restoring the radial bow with nails remain limited, so plating stays the default for displaced shaft fractures.

MIPO for the radius. Minimally invasive plating preserves fracture biology and gives comparable early outcomes in small series, but reproducing the radial bow blind risks malrotation. Reserve it for surgeons experienced with the technique and for simpler patterns.

Routine implant removal. No consensus supports prophylactic plate removal, and most removals are unnecessary.

The borderline DRUJ. When the DRUJ is reduced but only "soft" intraoperatively, the choice between cast immobilisation in supination, K-wire transfixation and TFCC repair is unsettled. Meta-analysis shows persistent instability is rare whichever is chosen, favouring the least invasive stable option.

Non-operative thresholds in adults. The displacement and angulation a load-sharing radius can tolerate without functional rotation loss is debated. Most surgeons fix anything that is displaced, rotated or shortened, given the cam effect of even small malalignment.

Bone grafting comminuted fractures. Primary grafting is generally unnecessary if length, alignment and stability are restored, but the role of biologic augmentation in segmental loss (Masquelet, early grafting or vascularised graft) is still individualised.