Forearm Shaft Fracture (Adult)
High-yield overview
Diaphyseal Radius and Ulna Fractures - The 'Forearm Joint'. ORIF with 3.5mm compression plates remains the gold standard treatment for displaced adult injuries.
1-2%Adult Fractures
95%+ORIF Union Rate
2-9%Synostosis Risk
AO/OTA 22
22A
PatternSimple (Spiral, oblique, or transverse patterns)
TreatmentORIF Plating
22B
PatternWedge (Intact or fragmentary wedge fractures)
TreatmentORIF Plating
22C
PatternComplex (Multifragmentary, segmental, or complex patterns)
TreatmentORIF Plating
Critical Must-Knows
- Restoration of the radial bow is critical for rotation; loss of bow creates a mechanical block.
- The 6-cortex rule (minimum 3 screws per fragment) is the mechanical requirement for stable fixation.
- Always exclude Monteggia (ulna + radial head) and Galeazzi (radius + DRUJ) injuries by imaging elbow/wrist.
- Volar compartments are at highest risk for compartment syndrome; check pain on passive stretch.
Clinical Pearls
- "The PIN is at highest risk in proximal Henry approaches; protect by fully supinating the forearm.
- "Synostosis risk increases from 2% to 11% if a single incision is used for both bones.
- "Isolated ulnar fractures ('Nightstick') with under 50% displacement and under 10° angulation can be treated in a brace.
Clinical Imaging
Imaging Gallery
Critical Exam Concepts
The Forearm Joint
Functionally, the forearm is a single articular unit. The radius rotates around the fixed ulna. Anatomic reduction is mandatory in adults to restore pronation/supination.
Restore Radial Bow
Restoring the lateral radial bow is critical. A straight radius blocks rotation. Fixation requires 3.5mm compression plates manually contoured to the bow.
The 6-Cortex Rule
For definitive fixation, a minimum of 6 cortices (3 screws) on each side of the fracture is required to prevent instability and nonunion.
At a Glance
Quick Decision Matrix: Management
| Injury | Criteria | Management |
|---|---|---|
| Undisplaced Isolated Ulna | under 50% disp, under 10° ang | Functional Brace |
| Both-Bone Fracture | Displaced | ORIF (DCP/LCP) |
| Monteggia/Galeazzi | Fracture + Joint Dislocation | Emergency ORIF + Joint Stability |
Mnemonic
SP-PDeforming Forces
| S | Supinated Proximal fragment (Biceps/Supinator) if proximal to PT |
| P | Pronated Distal fragment (PT + PQ) if proximal to PT |
| P | Pronated Distal fragment (PQ only) if distal to PT |
| S | Supinated Proximal fragment (Biceps/Supinator) if proximal to PT |
| P | Pronated Distal fragment (PT + PQ) if proximal to PT |
| P | Pronated Distal fragment (PQ only) if distal to PT |
Hook:Supinators are up top, Pronators are down low. Muscle pull based on fracture level relative to Pronator Teres (PT).
Mnemonic
MU-RNerve Review
| M | Median AIN checks: OK sign / FPL |
| U | Ulnar Interossei / Sensation |
| R | Radial PIN checks: Finger extension |
| M | Median AIN checks: OK sign / FPL |
| U | Ulnar Interossei / Sensation |
| R | Radial PIN checks: Finger extension |
Hook:Median, Ulnar, Radial cross the forearm. Key nerves at risk in forearm trauma.
Mnemonic
GRU-MGaleazzi vs Monteggia
| G | Galeazzi Radius fracture + DRUJ |
| R | Radio-distal Joint involved |
| U | Ulna Ulna fracture + Radial head dislocation |
| M | Monteggia Monteggia-Ulna association |
| G | Galeazzi Radius fracture + DRUJ | U | Ulna Ulna fracture + Radial head dislocation |
| R | Radio-distal Joint involved | M | Monteggia Monteggia-Ulna association |
Hook:Galeazzi-Radius-Ulna-Monteggia. Differentiating complex forearm patterns.
Overview and Epidemiology
Adult forearm shaft fractures are significant injuries because the forearm behaves as a functional joint allowing an average rotation of 180°. Unlike many other long bone fractures, non-operative management of displaced adult forearm fractures leads to poor functional outcomes, loss of rotation, and high nonunion rates.
Key Statistics:
- Incidence: Approximately 1-2% of all adult fractures.
- Demographics: Bimodal distribution. Young males (15-30) related to high-velocity trauma; older females (greater than 65) related to low-energy osteoporotic falls.
- Location: Most commonly involve both bones (60%); isolated ulna (25%) and isolated radius (15%) are less frequent.
Mechanism of Injury:
- High-Energy: MVA, motorcycle accidents, falls from height. Leads to comminution and significant soft tissue compromise.
- Low-Energy: Ground-level falls in the elderly.
- Direct Blow: The "Nightstick" fracture occurs when an individual raises their arm to protect against a strike (classic defensive injury).
Anatomy/Biomechanics
The forearm consists of the radius and ulna, which are connected by the Interosseous Membrane (IOM). Functionally, it is a ring structure; a fracture with displacement in one bone almost always implies a second fracture or a dislocation of either the proximal (PRUJ) or distal (DRUJ) radioulnar joint.
1. The Interosseous Membrane (IOM):
- Structure: Complex ligamentous structure with 5 parts.
- Central Band: The strongest portion, providing 70% of the longitudinal stiffness.
- Function: Transfers load from the radius to the ulna and maintains the relationship between the two bones during rotation.
2. The Radial Bow:
- The radius is not straight but has a lateral convex curvature; the apex lies at the junction of the proximal and middle thirds (pronator teres insertion).
- Axis of rotation: A line from the centre of the radial head proximally to the ulnar fovea distally; the radius rotates around the fixed ulna while the IOM maintains tension throughout the arc.
- Clinical Significance: Loss of the bow (straightening the radius) produces a mechanical block to rotation and significant loss of supination/pronation. Schemitsch and Richards (1992) showed that restoration of the magnitude and location of the radial bow to within approximately 5% of the contralateral limb correlates directly with the recovered rotational arc and grip strength.
3. Muscle Deforming Forces:
- Supinators: Biceps brachii (proximal insertion on radial tuberosity) and Supinator muscle (proximal).
- Pronators: Pronator teres (middle) and Pronator quadratus (distal).
- Fracture proximal to PT insertion: Proximal fragment is supinated; distal fragment is pronated.
- Fracture distal to PT insertion: Proximal fragment stays neutral (counterbalanced); distal fragment remains pronated by PQ.
Pathophysiology of Bone Healing
Fracture healing in the forearm requires a delicate balance between mechanical stability and molecular signaling. In the context of ORIF with compression plating, the goal is absolute stability, leading to primary (direct) bone healing.
1. Molecular Signaling Phase:
- Immediate release of pro-inflammatory cytokines:
TNF-alpha,IL-1beta,IL-6, andIL-10. - Activation of the MAPK (Mitogen-Activated Protein Kinase) and NF-kappaB pathways in osteoblast precursors.
- Recruitment of mesenchymal stem cells (MSCs) via
SDF-1andCXCR4gradients.
2. Primary Bone Healing (Absolute Stability):
- Occurs when fracture gaps are under 0.1mm and strain is under 2%.
- No external callus is formed.
- Cutting Cones: Osteoclasts (formed via
RANKL/OPGsignaling) tunnel across the fracture site, followed by osteoblasts depositing new lamellar bone. - Key growth factors:
BMP-2,BMP-4,BMP-7, andTGF-beta1.
3. Secondary Bone Healing (Relative Stability/Gaps):
- Occurs if bridging or IM nailing is used.
- Inflammation: Hematoma formation and fibrin clot.
- Soft Callus: Chondrocytes produce Type II collagen; regulated by
Sox9. - Hard Callus: Endochondral ossification; Type X collagen and
VEGFfor angiogenesis. - Remodeling: Conversion of woven bone to lamellar bone over months/years.
Classification Systems
AO/OTA Region 22 (Forearm):
- 22A: Simple Fracture
- 22A1: Simple ulna, radius intact
- 22A2: Simple radius, ulna intact
- 22A3: Simple both bones
- 22B: Wedge Fracture
- 22B1: Wedge ulna, radius intact
- 22B2: Wedge radius, ulna intact
- 22B3: Wedge both bones
- 22C: Complex Fracture
- 22C1: Complex ulna, radius intact
- 22C2: Complex radius, ulna intact
- 22C3: Complex both bones
The AO system provides a standardized language for describing fracture morphology and complexity.
Clinical Assessment
A thorough clinical assessment is mandatory to exclude limb-threatening complications, particularly compartment syndrome.
Clinical Presentation:
- Obvious deformity, swelling, and localized tenderness.
- Patient often supports the injured limb in a neutral position.
- Significant pain with any attempt at passive or active rotation.
Physical Exam Pearls:
- Skin Integrity: High incidence of open fractures in the forearm (ulna is subcutaneous). Check for small "poke-through" wounds.
- Neurovascular Status:
- AIN (Median N): Check "OK sign" (FPL/FDP index).
- PIN (Radial N): Check finger extension at MP joints (EIP/EDC).
- Ulnar N: Check interossei strength and sensation in the 5th digit.
- Joint Stability: Always palpate the elbow (PRUJ) and the wrist (DRUJ). Tenderness at these joints suggests a Galeazzi or Monteggia pattern.
- Compartment Check: Palpate for tenseness. The most sensitive sign is pain on passive stretch of the fingers (extension for volar compartment).
Investigations
1. Plain Radiographs:
- Views: AP and Lateral of the entire forearm.
- Requirement: Must include the elbow AND the wrist joints on the same film or separate orthogonal views of the joints.
- Check for "Parallelism": On a true lateral, the radius and ulna should appear parallel. Crossing or overlap suggests malrotation or dislocation.
2. Specific Signs of Dislocation:
- Monteggia: The radiocapitellar line must intersect the center of the capitellum in all views.
- Galeazzi: Look for signs of DRUJ instability:
- Ulnar styloid fracture at its base.
- Widening of the DRUJ on AP view (greater than 2mm).
- Dorsal/Volar displacement of the ulna relative to the radius on the lateral view.
- Radial shortening greater than 5mm relative to the distal ulna.
3. CT Scanning:
- Rarely indicated for simple shaft fractures.
- Useful for complex intra-articular extension (elbow/wrist) or planning for nonunion surgery.
4. MRI:
- Reserved for suspected IOM injury (Essex-Lopresti suspected) or assessing occult tendon/joint injury.
Management Algorithm
+-----------------------------------------------------------+
| Adult Forearm Shaft Fracture Assessment |
| (Clinical Exam + AP/Lat Elbow & Wrist) |
+-----------------------------------------------------------+
|
+-------------+-------------+
| |
[Isolated Ulna Shaft] [Radius or Both Bones]
| |
+-------+-------+ +-------+-------+
| | | |
[Stable/Simple] [Unstable] [ORIF GOLD STANDARD]
(under 50% disp, (greater than (3.5mm Comp Plates)
under 10° ang) 50% disp) |
| | +-------+-------+
[FUNCTIONAL [ORIF 3.5mm] | |
BRACE] | [Henry Volar] [Thompson/Ulna]
| | (Radius) (Radius/Ulna)
[Weekly X-ray] [6-Cortex] | |
(x 3 weeks) [Rule] [PIN Safety] [Internervous]
| | [Supination] [Planes]
+-------+-------+ | |
| +-------+-------+
| |
+-------------+-------------+
|
[Post-operative Protocol]
[0-2w: Splint + Elevation]
[2-6w: Early AROM No-Load]
[6-12w: Advancing Load ]
[12w+: Return to Activity]
Timing of Surgery
In closed injuries without compartment syndrome, surgery can be delayed until soft tissues are favorable. However, open fractures require urgent debridement and stabilization. In both-bone fractures, if one bone is simple and one is complex, fix the simple fracture first to restore length, then fix the complex one.
Surgical Technique
Radius:
- Proximal/Middle Third: Henry Approach (volar). Internervous plane between Brachioradialis (Radial N) and PT/FCR (Median N). Caution: PIN as it wraps around the radius in the supinator.
- Distal Third: Henry Approach is standard.
- Dorsal (Thompson) Approach: Internervous plane between ECRB (Radial N) and ED (PIN). Best for proximal/middle third radial neck or dorsal pathology.
Ulna:
- Subcutaneous Approach: Direct incision over the subcutaneous border of the ulna. Internervous plane between FCU (Ulnar N) and ECU (PIN).
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PIN Safety (Henry Approach)
When performing a proximal Henry approach, the PIN is at risk. It should be protected by supinating the forearm during dissection; this moves the PIN laterally away from the radial neck and protects it within the supinator muscle fibers.
The 10-Step Forearm ORIF
- Positioning: Supine on a hand table with a tourniquet.
- Approach: Standard Henry or Thompson (Radius) and Subcutaneous (Ulna).
- Reduction: Direct reduction with pointed reduction forceps. Restore radial bow apex.
- Provisional Fixation: K-wires or forceps.
- Plate Selection: 3.5mm LCDCP or LCP (contoured).
- Lag Screwing: If oblique/spiral pattern exists.
- Compression: Apply across the transverse component.
- Screw Placement: Achieve 6 cortices minimum per fragment.
- Irrigation/Closure: Hemostasis, layered closure.
- Assessment: Confirm full pronation/supination arc under GA.
Complications
1. Compartment Syndrome:
- Incidence: 1-10% (highest in high-energy or crush injuries).
- Three compartments at risk: Volar (FPL/FDP - most commonly affected), Dorsal (extensors), and the Mobile Wad (BR, ECRL, ECRB - often overlooked).
- Earliest sign: pain out of proportion, then pain on passive finger extension (stretches the volar flexors); the median nerve is affected first.
- Management: Emergency dual-incision (volar + dorsal) fasciotomy releasing all three compartments.
2. Nerve Injuries:
- PIN Palsy: Most common with proximal radius surgery; the dorsal (Thompson) approach carries a documented postoperative PIN palsy rate of approximately 18% even when the nerve is identified and protected (Perretta and Tejwani, 2016). Usually a transient neurapraxia.
- Median/Ulnar Nerve: Higher risk in distal third fractures or penetrating trauma.
- Across pooled compression-plating series, postoperative nerve injury is the single most common adverse event (approximately 7%; Vasara et al., 2024).
3. Infection:
- Risk: under 2-3% in closed fractures; significantly higher in Gustilo III open fractures (deep infection approximately 2-4% even with immediate fixation of open injuries; Moed et al., 1986).
- Management: I&D, retention of hardware if stable, suppressive antibiotics.
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Postoperative Care and Rehabilitation
Phase I: Protection (0-2 Weeks):
- Splint or heavy dressing in neutral rotation.
- Elevation and finger ROM to minimize edema.
- Neurovascular checks in postoperative clinic.
Phase II: Functional Range of Motion (2-6 Weeks):
- Suture removal.
- Active and active-assisted ROM (flexion/extension/pronation/supination).
- Lifting restricted to "cup of tea" weight.
Phase III: Strengthening (6-12 Weeks):
- Progressive resistance once early bridging callus is visible.
- Weight-bearing status progressed based on radiology.
Outcomes and Prognosis
Adult forearm ORIF consistently achieves high union and good function.
- Union Rate: Over 95% with modern 3.5mm compression plating in closed injuries.
- Range of Motion: Most patients recover a functional rotational arc when the radial bow and length are anatomically restored; a good result (over 80% of normal rotation) tracks with restoration of the bow (Schemitsch & Richards, 1992).
- Patient Scores: Pooled DASH scores average around 12.5, i.e. good function with a minor residual disability in some patients (Vasara et al., 2024). Subjective weakness can persist despite an objectively good arc.
Evidence Base
Anderson et al. (1975) - Landmark
Anderson LD, Sisk D, Tooms RE, Park WI • J Bone Joint Surg Am (1975)
Retrospective Case Series
Key Findings:
- Radius union 97.9%, ulna union 96.3%
- Established rigid compression plating as definitive treatment
- Underpins the modern 6-cortex / 3.5mm plating principle
Finding: Classic series of 244 patients with 330 acute diaphyseal radius and ulna fractures treated with ASIF compression plates and followed up to 9 years.
Clinical Implication: Established ORIF with rigid compression plating as the definitive standard for displaced adult forearm fractures.
Schemitsch & Richards (1992) - Landmark
Schemitsch EH, Richards RR • J Bone Joint Surg Am (1992)
Clinical Cohort Study
Key Findings:
- Restoring the normal radial bow correlated with a good result (over 80% of normal rotation, p less than 0.05)
- Recovery of grip strength linked to restoring the location of the bow (p less than 0.005)
- 84% achieved an excellent/good/acceptable result
Finding: 55 adults with plated both-bone forearm fractures, followed a mean of 6 years, quantifying how the magnitude and location of the radial bow drive function.
Clinical Implication: Manual contouring of the plate to reproduce the normal magnitude and location of the radial bow is mandatory for optimal rotation and grip.
Chapman et al. (1989)
Chapman MW, Gordon JE, Zissimos AG • J Bone Joint Surg Am (1989)
Retrospective Case Series
Key Findings:
- 98% union rate; 92% excellent or satisfactory function
- Infection rate 2.3%
- No refractures after removal of a 3.5mm plate (vs refracture after 4.5mm) - basis for choosing 3.5mm implants
Finding: 87 patients with 129 diaphyseal radius/ulna fractures fixed with AO dynamic compression plates, including primary fixation of open fractures.
Clinical Implication: Confirms rigid 3.5mm plate fixation gives high union with low complications and minimises refracture after hardware removal.
Vasara et al. (2024) - Systematic Review
Vasara H, Stenroos A, Aspinen S, Kosola J, Anttila T, Nordback PH • JB JS Open Access (2024)
Systematic Review
Key Findings:
- Overall adverse-event rate 24%; major (reoperation/persistent) 14%
- Most common AEs: nerve injury 7% and nonunion 5%
- Mean DASH 12.5 (range 0-61) - good function with minor residual disability
Finding: Systematic review of 15 studies (944 adults) of both-bone forearm fractures treated by compression plating, pooling adverse events and long-term outcomes.
Clinical Implication: Modern plating yields good function but counsel patients on a real adverse-event burden, dominated by nerve injury and nonunion.
Bergeron et al. (2012) - Review
Bergeron SG, Desy NM, Bernstein M, Harvey EJ • J Am Acad Orthop Surg (2012)
Narrative Review
Key Findings:
- Risk relates to injury severity and surgical management (e.g. single shared exposure)
- Patients present with complete loss of active and passive rotation
- Early resection at 6-12 months is safe once radiographs show bony maturation; low recurrence after primary excision
Finding: JAAOS review of post-traumatic radioulnar synostosis: risk factors, presentation, timing of excision and outcomes.
Clinical Implication: Synostosis is excised once mature (6-12 months); routine adjuvant prophylaxis is not mandatory after primary excision.
Nappo et al. (2019)
Nappo KE, Hoyt BW, Balazs GC, Nanos GP, Ipsen DF, Tintle SM, Polfer EM • Clin Orthop Relat Res (2019)
Retrospective Cohort
Key Findings:
- Final union 96% (primary 85%); nonunion linked to bone loss and infection
- Heterotopic ossification in 55%, radioulnar synostosis in 19%
- Synostosis (not HO alone) was the main driver of lost pronation-supination arc
Finding: 73 high-energy open forearm fractures in military combatants assessing union, heterotopic ossification and synostosis.
Clinical Implication: In high-energy open injuries union is achievable, but synostosis - not heterotopic bone per se - is what destroys rotation.
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ORIF vs IM Nailing (Adult Forearm)
| Metric | ORIF Plating | IM Nailing |
|---|---|---|
| Union Rate | 95-98% | 80-90% |
| Infection Risk | Low (under 2%) | Very Low |
| Rotational Control | Excellent | Poor |
Exam Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
CLINICAL SCENARIOStandard
Scenario 1: Both-Bone Forearm Fracture - ORIF Principles
CLINICAL PROMPT
"A 30-year-old male labourer presents to the emergency department after a fall from height, landing on his outstretched dominant right forearm. X-rays show displaced mid-shaft fractures of both the radius and ulna at the middle third level. The fractures are transverse with minimal comminution. Neurovascular examination is intact, the skin is closed, and there are no signs of compartment syndrome. How do you manage this patient?"
PRACTICAL APPROACH
This is a displaced **both-bone forearm fracture** in an active adult. The forearm functions as a **single articular unit** (the radius rotates around the fixed ulna during pronation and supination), so anatomic reduction is essential to restore full rotational range of motion. The standard treatment is **open reduction and internal fixation (ORIF) with compression plating**. My management approach would be: First, initial **assessment and resuscitation** following ATLS principles, ensuring this is an isolated injury. **Neurovascular examination** is critical - document median, radial, and ulnar nerve function, as well as radial and ulnar pulses. Assess for compartment syndrome (pain out of proportion, pain on passive stretch, paresthesias, tense compartments) - this is a surgical emergency. **Imaging**: Full-length forearm X-rays including **AP and lateral views of the wrist AND elbow joints** to exclude associated injuries. Always check for **Monteggia injury** (ulna fracture with radial head dislocation - check radiocapitellar line on lateral elbow X-ray) and **Galeazzi injury** (radius fracture with distal radioulnar joint disruption - check DRUJ on lateral wrist X-ray, palpate ulnar styloid). **Timing**: Ideally operate within 24-48 hours, though this is not an emergency unless neurovascular compromise or compartment syndrome develops. **Surgical plan**: The procedure is **ORIF of both bones with 3.5mm compression plates** (DCP or LCP). Critical principle: Use **separate incisions** to reduce risk of radioulnar synostosis (2-9% complication). For the **radius**, I would use the **volar (Henry) approach** for middle/distal fractures - the interval is between brachioradialis (radial nerve) and flexor carpi radialis (median nerve), separating the mobile wad from the flexor wad. For proximal radius fractures, the **dorsal (Thompson) approach** may be needed - interval between ECRB and EDC, but watch for posterior interosseous nerve (PIN) which is at risk within the supinator muscle. For the **ulna**, use the subcutaneous border approach - interval between FCU and ECU. **Fixation technique**: Apply **3.5mm LC-DCP or locking plates** with a minimum of **6 cortices (3 screws) on each side** of the fracture per Anderson's 1975 landmark study. Achieve compression at the fracture site using either lag screws through the plate or compression plate technique. **Critical step for the radius**: Restore the **radial bow** (the natural lateral curvature of the radius). The Schemitsch and Richards study (JBJS 1992) showed strong correlation between restoration of radial bow and functional outcome - failure to restore the bow leads to loss of rotation. Use pre-contoured plates or manually contour the plate to match the normal curve, with maximum bow at the junction of proximal and middle thirds. **Sequence**: I typically fix the simpler fracture first to restore length, then use that as a reference for the second bone. Post-operatively, with rigid fixation achieved, **no cast is required**. Start **early active range of motion** to prevent stiffness. Lifting restrictions apply until clinical and radiological union (typically 12-16 weeks). **Hardware removal**: Leave plates in permanently unless they become symptomatic. There is a **3-10% risk of refracture** after plate removal, so if removal is necessary, wait at least 18 months and counsel the patient about this risk.
KEY CLINICAL POINTS
Forearm = joint (radius rotates around ulna) requiring anatomic reduction for full pronation/supination 180° arc
ORIF with 3.5mm compression plates, minimum 6 cortices (3 screws) each side of fracture (Anderson 1975)
Separate incisions mandatory: Henry volar approach for radius, subcutaneous for ulna (prevents synostosis 2-9%)
Restore radial bow critical for rotation (Schemitsch & Richards 1992) - maximum bow at junction proximal/middle thirds
Exclude Monteggia (ulna fracture + radial head dislocation) and Galeazzi (radius fracture + DRUJ disruption) - always image elbow AND wrist
COMMON PITFALLS
Single incision for both bones (significantly increases synostosis risk from 2% to 9%)
Applying straight plate to radius without restoring radial bow (loss of rotation)
Using IM nails in adults (high malunion/nonunion rate, poor rotational control - avoid except specific indications)
Inadequate fixation with fewer than 6 cortices per fragment (increases nonunion risk)
FURTHER QUESTIONS
"Why use 3.5mm plates specifically rather than 2.7mm or 4.5mm plates?"
"Describe the anatomy of the Henry approach in detail including intervals and structures at risk"
"What is the mechanism and management of radio-ulnar synostosis?"
CLINICAL SCENARIOChallenging
Scenario 2: Nightstick Fracture and Compartment Syndrome Recognition
CLINICAL PROMPT
"A 45-year-old man presents after an assault where he raised his forearm to block a blow from a baseball bat. X-rays show an isolated ulnar shaft fracture at the middle third with 60% displacement and 15 degrees of angulation. There is no radial fracture. He is complaining of severe pain in the forearm that seems out of proportion to the injury, and pain is worse with passive finger extension. The forearm feels tense on palpation. What are your immediate concerns and how do you proceed?"
PRACTICAL APPROACH
This patient has sustained a **nightstick fracture** - an isolated ulna shaft fracture from direct blow, classically a defensive injury when blocking a strike. However, I am immediately concerned about **impending compartment syndrome** based on several red flags: pain out of proportion to injury, pain with passive finger extension (stretching the volar compartment), and tense forearm on palpation. This is a surgical emergency that takes priority over the fracture fixation. The forearm has **three compartments** at risk: **volar** (most commonly affected, containing FDP and FPL), **dorsal** (extensors), and **mobile wad** (brachioradialis, ECRL, ECRB). Let me address both issues systematically. First, regarding **compartment syndrome assessment**: The clinical diagnosis is based on the **five Ps** but relying on late signs (paralysis, pulselessness, pallor) is catastrophic - these indicate irreversible damage. The **earliest and most reliable sign is pain out of proportion**, followed by **pain on passive stretch** of the affected compartment. For the volar compartment, passive extension of the fingers stretches FDP/FPL and causes severe pain. Paresthesias in the median nerve distribution may occur (first nerve affected). If I have **high clinical suspicion**, I would proceed directly to **fasciotomy** without delay. Compartment pressure measurement can be used if diagnosis is equivocal - absolute pressure greater than 30mmHg or delta pressure (diastolic BP minus compartment pressure) less than 30mmHg are concerning, but clinical diagnosis supersedes numbers. **Immediate management** if compartment syndrome confirmed or highly suspected: Emergency **forearm fasciotomy** via **two-incision technique** - volar (Henry approach releasing volar compartment and mobile wad) and dorsal (releasing dorsal compartment). All three compartments must be released. Time is critical - irreversible muscle necrosis occurs after 6-8 hours. Leave wounds open, plan delayed closure or skin grafting at 48-72 hours. Now, regarding the **nightstick fracture management**: Once compartment syndrome is addressed, I need to decide on fracture treatment. Management depends on displacement and stability. For **isolated ulna fractures**: If less than 50% displacement AND less than 10 degrees angulation, **non-operative management** with functional bracing is acceptable - the intact radius provides some stability. However, this patient has **60% displacement and 15 degrees angulation**, which exceeds these thresholds and indicates **operative treatment is required**. Before proceeding, I must exclude **associated injuries**. An 'isolated' ulna fracture should raise suspicion for **Monteggia injury** - proximal ulna fracture with radial head dislocation. I would carefully review the X-rays to ensure full-length forearm views including elbow and wrist joints. On the **lateral elbow view**, draw the **radiocapitellar line** (line through the center of the radial neck should bisect the capitellum in all views) - if this is disrupted, there is radial head dislocation requiring urgent reduction. For the nightstick fracture fixation (after compartment release if needed), the approach is **subcutaneous ulnar border approach** with **3.5mm compression plate** (LC-DCP or LCP). Apply minimum 6 cortices each side. Compression technique if fracture pattern allows. If I had to perform compartment fasciotomy, I would **delay definitive fixation** until soft tissues improve (external fixator or temporary splint), then do delayed ORIF at 5-7 days once swelling subsides and wounds are closing. Post-operatively, monitor closely for complications including infection (especially if fasciotomy performed), nonunion (2-5% with compression plating), and refracture if plate removed.
KEY CLINICAL POINTS
Nightstick fracture = isolated ulna from direct blow, less than 50% displacement and less than 10° angulation can be treated non-operatively with functional brace
Compartment syndrome: Pain out of proportion + pain on passive stretch most reliable early signs, don't wait for 5 Ps (late)
Forearm has 3 compartments (volar most common, dorsal, mobile wad) - emergency fasciotomy via volar and dorsal incisions releases all
Always exclude Monteggia injury with isolated ulna fracture: Check radiocapitellar line on lateral elbow X-ray (line through radial neck bisects capitellum)
60% displacement or greater than 10° angulation requires ORIF with 3.5mm compression plate via subcutaneous ulnar border approach
COMMON PITFALLS
Waiting for late signs of compartment syndrome (5 Ps) before fasciotomy - irreversible damage already occurred
Relying on compartment pressure measurements over clinical diagnosis (false reassurance, delays surgery)
Missing Monteggia injury - not imaging elbow joint with 'isolated' ulna fracture
Performing definitive ORIF immediately in presence of compartment syndrome (delay fixation after fasciotomy, stage surgery)
FURTHER QUESTIONS
"What are the compartments of the forearm and their contents?"
"How do you perform a forearm fasciotomy - describe the incisions and anatomy?"
"What is the time window for irreversible muscle damage in compartment syndrome?"
CLINICAL SCENARIOCritical
Scenario 3: Radio-Ulnar Synostosis - Devastating Complication
CLINICAL PROMPT
"You are asked to see a 35-year-old man in clinic who underwent ORIF of both-bone forearm fractures 9 months ago at another hospital. He is very frustrated because despite the fractures healing well on X-ray, he has essentially no pronation or supination - his forearm is fixed in approximately 30 degrees of pronation. He works as an electrician and cannot perform his job. X-rays show healed radius and ulna fractures with well-positioned plates, but there is a 4cm bridge of heterotopic bone connecting the radius and ulna in the middle third of the forearm. What has happened and how do you manage this complication?"
PRACTICAL APPROACH
This patient has developed **radio-ulnar synostosis** (cross-union or heterotopic ossification bridging the radius and ulna), which is one of the most devastating complications of forearm fracture fixation because it eliminates pronation and supination by converting the forearm from a mobile unit into a fixed bone bridge. This complication occurs in **2-9% of both-bone forearm fractures**, with incidence at the higher end when risk factors are present. Let me analyze what went wrong and outline management. **Pathophysiology and risk factors**: Synostosis occurs when heterotopic bone formation bridges the interosseous space between radius and ulna, eliminating the mobile articulation. The likely **risk factors** in this case include: **single-incision approach** (highest risk factor - using one incision to expose both bones drastically increases synostosis risk from approximately 2% to 9%), **high-energy trauma**, **severe soft tissue injury**, **head injury** (increases heterotopic ossification risk), **delayed fixation** allowing extensive periosteal stripping, and **infection**. The original operative note would be critical to review - if a single volar or dorsal incision was used to plate both bones, this directly caused the problem. **Clinical impact**: The patient is fixed in 30 degrees pronation. **Functional position** of the forearm for activities of daily living requires a **rotational arc of approximately 100 degrees** (50 degrees pronation to 50 degrees supination from neutral). For most activities, if fixed in neutral (0 degrees), patients can compensate with shoulder rotation. However, this patient is fixed in pronation, making tasks like turning a screwdriver, opening a door, or using a keyboard extremely difficult. For an electrician whose work requires frequent forearm rotation, this is devastating. **Current assessment**: At 9 months post-injury, the synostosis is likely mature. I would obtain **CT scan** to define the exact location, width, and extent of the bony bridge. This guides surgical planning. Rule out **infection** with inflammatory markers (CRP/ESR) - if there was underlying infection, this must be addressed before reconstruction. **Management options**: The primary treatment is **surgical excision of the synostosis**. However, this is complex and has significant **recurrence risk** (up to 20-30% even with prophylaxis). I would counsel the patient about realistic expectations. **Timing**: Synostosis excision should ideally be delayed until the heterotopic bone is **mature** (typically 12-18 months post-injury, or 6-12 months from when synostosis was first noted). Excising immature heterotopic bone has very high recurrence rates. Some surgeons wait for alkaline phosphatase to normalize and bone scan to show maturity. At 9 months, this patient is borderline - I would obtain bone scan and consider waiting another 3-6 months for full maturity. **Surgical technique**: Via **separate incisions** (learning from the original error), expose the synostotic bridge. Use careful subperiosteal dissection to minimize further trauma. Excise the heterotopic bone completely back to normal cortex of both radius and ulna. The interosseous membrane is usually incorporated into the synostosis and must be reconstructed or accepted as lost. Ensure there is at least **3cm of cleared space** between radius and ulna. Some surgeons interpose muscle (anconeus) or fat to prevent recurrence. **Prophylaxis against recurrence** is critical: **Indomethacin** 25mg three times daily for 6 weeks post-operatively (inhibits heterotopic ossification). **Low-dose radiation therapy** (7-8 Gy single fraction within 72 hours of surgery) is the most effective prophylaxis - reduces recurrence from 30% to less than 10%. However, radiation has long-term concerns (theoretical malignancy risk, though very low with single dose) and requires radiation oncology involvement. I would discuss risks/benefits with the patient. **Post-operative rehabilitation**: Immediate active ROM exercises are critical. CPM machine may be used. Aggressive physiotherapy to maximize regained motion before any scar contracture or recurrence occurs. **Alternative if surgery fails or patient declines**: **Adaptive strategies** and **occupational therapy** to modify work tasks. **Osteotomy** to reposition the forearm in neutral or slight supination (more functional position than pronation) is an option, though this accepts the loss of rotation and just optimizes fixed position. **Prevention**: The key teaching point is that this complication is often **preventable** with proper initial surgical technique. **Always use separate incisions** for radius and ulna fixation. Minimize soft tissue stripping. Early fixation (within 24-48 hours) may reduce periosteal trauma. Avoid excessive soft tissue dissection in the interosseous space.
KEY CLINICAL POINTS
Radio-ulnar synostosis = heterotopic bone bridging radius and ulna, eliminates pronation/supination, devastating complication 2-9%
Risk factors: Single incision approach (highest risk, increases from 2% to 9%), high energy trauma, severe soft tissue injury, head injury, delayed fixation
Excision surgery delayed until maturity (12-18 months post-injury or 6-12 months from onset, bone scan shows maturity, normalized ALP)
Recurrence prevention critical: Indomethacin 25mg TDS for 6 weeks + low-dose radiation (7-8 Gy single fraction within 72h, reduces recurrence from 30% to less than 10%)
Prevention is key: ALWAYS use separate incisions for radius and ulna, minimize soft tissue stripping, early fixation
COMMON PITFALLS
Excising immature synostosis (very high recurrence rate - must wait for maturity 12-18 months)
Not providing heterotopic ossification prophylaxis after excision (30% recurrence vs less than 10% with indomethacin + radiation)
Using single incision approach initially (directly causes synostosis in up to 9% vs 2% with separate incisions)
Promising full restoration of rotation (even with successful excision, patients often regain 70-80% of normal rotation, not 100%)
FURTHER QUESTIONS
"What is the mechanism of action of indomethacin in preventing heterotopic ossification?"
"How does low-dose radiation therapy prevent heterotopic bone formation?"
"What is the functional arc of forearm rotation required for activities of daily living?"
MCQ Practice Points
Key Fact
Q: Why is ORIF the standard treatment for adult forearm shaft fractures?
A: The forearm functions as a ring structure requiring anatomic restoration for pronation/supination (180° arc). Non-anatomic reduction causes loss of rotation and radioulnar synostosis. Radial bow must be restored - maximum bow at junction of proximal and middle thirds. Cast treatment acceptable only for isolated ulna fractures with minimal displacement.
Key Fact
Q: What is the optimal plate position for forearm fractures?
A: Radius: Volar (Henry) approach - plate on volar surface (tension side); Thompson approach - plate on dorsal surface. Ulna: Plate on dorsal or medial surface (tension side), avoiding subcutaneous border. 3.5mm LC-DCP or locking plates. Minimum 6 cortices (3 screws) each side of fracture. Compression plating preferred.
Key Fact
Q: What is a nightstick fracture and its treatment?
A: Isolated ulna shaft fracture from direct blow (defensive injury blocking strike). Treatment depends on displacement: Less than 50% displacement and less than 10° angulation: Cast/functional bracing acceptable. Greater than 50% displacement: ORIF. Associated injuries (radial head dislocation = Monteggia) must be excluded - always image elbow and wrist.
Key Fact
Q: What must be assessed with any isolated forearm bone fracture?
A: Always assess for associated joint injury: Monteggia: Ulna fracture + radial head dislocation (check radiocapitellar line). Galeazzi: Radius fracture + DRUJ disruption (check DRUJ on lateral, ulnar fovea tenderness). Essex-Lopresti: Radial head fracture + IOM disruption + DRUJ instability. "Fracture of necessity."
Key Fact
Q: What is the risk of compartment syndrome in forearm fractures?
A: Forearm has three compartments (volar, dorsal, mobile wad) all at risk. High-energy fractures, crush injuries, and combined radius-ulna fractures increase risk. Volar compartment most commonly affected. Monitor closely post-op. Fasciotomy via volar (Henry) + dorsal incisions if suspected. Median nerve first affected.
Guidelines, Registries & Global Practice
Adult forearm shaft fractures are managed with broadly convergent principles worldwide, with the main variation driven by resource setting and the timing/logistics of definitive care.
Global epidemiology
- Diaphyseal forearm fractures represent roughly 1-2% of adult fractures, with a bimodal pattern: high-energy injuries in young men (road traffic and sport) and low-energy osteoporotic injuries in older women.
- High-energy and open patterns predominate where road-traffic and occupational trauma are common; fragility-type injuries dominate in ageing populations.
Side-by-side society guidance
- AO Foundation: Anatomic reduction, restoration of the radial bow, and absolute stability with 3.5mm compression plates (minimum 3 screws / 6 cortices per main fragment) for displaced injuries.
- AAOS / general trauma consensus (US): ORIF is standard for displaced both-bone and displaced isolated radius fractures; selected isolated ulnar (nightstick) fractures with under 50% displacement and under 10° angulation are braced.
- BOA / BOAST (UK) open-fracture principles: Prompt IV antibiotics, early senior-led debridement, and combined ortho-plastic management with early definitive skeletal fixation and soft-tissue cover for open injuries (the ulna is subcutaneous and frequently open).
- EFORT / European practice: Similar plate-osteosynthesis emphasis; intramedullary nailing is reserved for selected segmental or open injuries with poor soft tissues rather than as a default in adults.
Registry and outcome signals
- There is no dedicated arthroplasty-style registry for forearm shaft fractures; the best pooled outcome data come from systematic review (Vasara et al., 2024): 944 adults, 24% adverse-event rate, nerve injury approximately 7% and nonunion approximately 5%, mean DASH 12.5.
High- vs limited-resource variation
- In well-resourced systems, displaced fractures undergo early ORIF, often within 24-72 hours once soft tissues allow.
- In limited-resource or remote settings, initial management is a well-padded above-elbow backslab in neutral rotation with the elbow at 90°, then transfer for definitive plating; the "image both joints" rule (elbow and wrist) is critical at first contact to avoid missing a Galeazzi or Monteggia pattern.
- Functional outcome scores (e.g. DASH) are used internationally to track recovery and guide return to manual work.
Forearm Shaft Quick Reference
Clinical summary
Mandatory Steps
- •Include elbow AND wrist in all imaging.
- •Check PIN function (EIP/EDC) before every Henry approach.
- •Restore radial bow apex to within 5% of contralateral side.
- •Use 3.5mm plates with minimum 6 cortices per fragment.
Approaches
- •Radius Volar: Henry (Interval: BR & FCR)
- •Radius Dorsal: Thompson (Interval: ECRB & EDC)
- •Ulna: Subcutaneous (Interval: FCU & ECU)
Surgical Dangers
- •PIN in proximal third (Henry/Thompson).
- •Median Nerve (Henry approach retraction).
- •Synostosis (Single incision both-bone exposure).
- •Compartment Syndrome (Missed deep volar release).
References
- Anderson LD, Sisk D, Tooms RE, Park WI. Compression-plate fixation in acute diaphyseal fractures of the radius and ulna. J Bone Joint Surg Am. 1975;57(3):287-97. PMID: 1091653
- Schemitsch EH, Richards RR. The effect of malunion on functional outcome after plate fixation of fractures of both bones of the forearm in adults. J Bone Joint Surg Am. 1992;74(7):1068-78. PMID: 1522093
- Chapman MW, Gordon JE, Zissimos AG. Compression-plate fixation of acute fractures of the diaphyses of the radius and ulna. J Bone Joint Surg Am. 1989;71(2):159-69. PMID: 2918001
- Moed BR, Kellam JF, Foster RJ, Tile M, Hansen ST. Immediate internal fixation of open fractures of the diaphysis of the forearm. J Bone Joint Surg Am. 1986;68(7):1008-17. PMID: 3745238
- Vasara H, Stenroos A, Aspinen S, Kosola J, Anttila T, Nordback PH. Both-Bone Forearm Shaft Fractures Treated with Compression Plate Fixation in Adults: A Systematic Review on Adverse Events and Outcomes. JB JS Open Access. 2024;9(4). PMID: 39600799 DOI
- Bergeron SG, Desy NM, Bernstein M, Harvey EJ. Management of posttraumatic radioulnar synostosis. J Am Acad Orthop Surg. 2012;20(7):450-8. PMID: 22751164 DOI
- Nappo KE, Hoyt BW, Balazs GC, Nanos GP, Ipsen DF, Tintle SM, Polfer EM. Union Rates and Reported Range of Motion Are Acceptable After Open Forearm Fractures in Military Combatants. Clin Orthop Relat Res. 2019;477(4):813-820. PMID: 30811353 DOI
- Perretta DJ, Brock KM, Tejwani NC. Early Complications Associated with the Thompson Approach to the Proximal Radius. Bull Hosp Jt Dis (2013). 2016;74(4):293-297. PMID: 27815953
- Ryan MK, MacKay BJ, Tejwani NC. Both-bone forearm fracture with distal radioulnar joint dislocation. Am J Orthop (Belle Mead NJ). 2013;42(5):E30-2. PMID: 23710483
- Galeazzi R. Di una particolare sindrome traumatica dello scheletro dell'avambraccio. Arch Ortop. 1934;50:823. (Historical citation - predates PubMed indexing)