Forearm Shaft Fracture (Adult)

High Yield Overview

Forearm Shaft Fracture (Adult)

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.

Examiner's 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

Supinated

Proximal fragment (Biceps/Supinator) if proximal to PT

Pronated

Distal fragment (PT + PQ) if proximal to PT

Pronated

Distal fragment (PQ only) if distal to PT

Memory Hook:Supinators are up top, Pronators are down low. Muscle pull based on fracture level relative to Pronator Teres (PT).

Mnemonic

MU-RNerve Review

Median

AIN checks: OK sign / FPL

Ulnar

Interossei / Sensation

Radial

PIN checks: Finger extension

Memory Hook:Median, Ulnar, Radial cross the forearm. Key nerves at risk in forearm trauma.

Mnemonic

GRU-MGaleazzi vs Monteggia

Galeazzi

Radius fracture + DRUJ

Radio-distal

Joint involved

Ulna

Ulna fracture + Radial head dislocation

Monteggia

Monteggia-Ulna association

Memory 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.
Apex of Bow: Located at the junction of the proximal and middle thirds (pronator teres insertion).
Clinical Significance: Loss of this bow (straightening the radius) results in a mechanical block to rotation and significant loss of supination/pronation.

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 supinatied; 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, and IL-10.
Activation of the MAPK (Mitogen-Activated Protein Kinase) and NF-kappaB pathways in osteoblast precursors.
Recruitment of mesenchymal stem cells (MSCs) via SDF-1 and CXCR4 gradients.

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/OPG signaling) tunnel across the fracture site, followed by osteoblasts depositing new lamellar bone.
Key growth factors: BMP-2, BMP-4, BMP-7, and TGF-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 VEGF for 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
- 22B2: 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.

Functional Anatomy and Biomechanics

The Forearm Joint:

Radius rotates around the fixed Ulna.
Axis of rotation: A line from the center of the radial head proximally to the ulnar fovea distally.
Interosseous membrane (IOM) connects them, maintaining tension throughout rotation.
Any disruption of the shaft implies potential joint disruption at either end (The 'Ring' Concept).

Radial Bow Restoration:

The radius is laterally convex; this curve is essential for pronation.
Schemitsch and Richards (1992) demonstrated that restoration of the radial bow to within 5% of the contralateral limb correlates directly with functional rotational arc.
Loss of bow results in "proximal" or "distal" mechanical blocks.

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).

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).
Volar Compartment (Deep): Most common. Check FPL/FDP.
Sign: Pain on passive finger extension.
Management: Emergency dual-incision fasciotomy.

Volar Compartment (Deep):

FPL and FDP muscles. Most commonly affected.
Sign: Pain on passive extension of fingers.

Dorsal Compartment:

Extensors. Reached via dorsal incision.

Mobile Wad:

BR, ECRL, ECRB. Often overlooked.

2. Nerve Injuries:

PIN Palsy: Most common with proximal radius surgery (Henry or Thompson approach). Usually temporary neuropraxia.
Median/Ulnar Nerve: Higher risk in distal third fractures or penetrating trauma.

3. Infection:

Risk: under 2-3% in closed fractures; significantly higher in Gustilo III open fractures.
Management: I&D, retention of hardware if stable, suppressive antibiotics.

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 functional scores.

Union Rate: greater than 95% success with modern 3.5mm compression plating.
Range of Motion: greater than 80% of Patients regain approximately 85% of their rotational arc if anatomical reduction is achieved.
Patient Scores: DASH (Disabilities of the Arm, Shoulder and Hand) scores typically settle in the "excellent" range by 12 months.

Evidence Base

Anderson et al. (1975)

Moderate

Anderson LD, Sisk TD, Tooms RE, Park WI 3rd • Journal of Bone and Joint Surgery (1975)

Retrospective Case Series

Key Findings:

98% union rate for radius, 96% for ulna
Defined the 6-cortex mechanical requirement
Standardized 3.5mm compression plating

Finding: Classic study defining the 6-cortex rule. 330 adult forearm fractures treated with ORIF.

Clinical Implication: Established ORIF with rigid compression plating as the definitive gold standard for adult injuries.

Schemitsch & Richards (1992)

High

Schemitsch EH, Richards RR • Journal of Bone and Joint Surgery (1992)

Clinical Cohort Study

Key Findings:

Restoration of bow to within 5% of contralateral limb is functional priority
Direct correlation between bow restoration and rotational arc

Finding: Prospective study of 129 fractures quantifying the importance of the lateral radial bow.

Clinical Implication: Manual contouring of the plate to match the normal radial curve is mandatory for optimal function.

Chapman et al. (1989)

High

Chapman MW, Gordon JE, Zissimos AG • Journal of Bone and Joint Surgery (1989)

Prospective Case Series

Key Findings:

98% union rate
Early ROM started within 2 weeks
Plating superior to IM nailing in adults

Finding: Prospective study confirming excellence of plate fixation.

Clinical Implication: Confirms that rigid fixation allows safe early mobilization without compromising union.

Goldfarb et al. (2005)

Moderate

Goldfarb CA, Ricci WM, Boyer MI • Journal of Bone and Joint Surgery (2005)

Retrospective Cohort Study

Key Findings:

DASH score average of 10 at long-term follow-up
Subjective weakness common despite functional arc

Finding: Assessed long-term functionality and DASH scores.

Clinical Implication: Patients reach excellent functional levels but should be counseled about potential subjective changes.

Moed et al. (1986)

High

Moed BR, Watson JT, Cramer KE • Journal of Bone and Joint Surgery (1986)

Prospective Case Series

Key Findings:

Immediate active ROM does not increase failure rates
Reduced incidence of synostosis with early motion

Finding: Safety of immediate mobilization.

Clinical Implication: Postoperative casting should be avoided in favor of early active movement.

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

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Scenario 1: Both-Bone Forearm Fracture - ORIF Principles

EXAMINER

"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?"

EXCEPTIONAL ANSWER

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 POINTS TO SCORE

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 TRAPS

✗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)

LIKELY FOLLOW-UPS

"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?"

VIVA SCENARIOChallenging

Scenario 2: Nightstick Fracture and Compartment Syndrome Recognition

EXAMINER

"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?"

EXCEPTIONAL ANSWER

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 POINTS TO SCORE

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 TRAPS

✗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)

LIKELY FOLLOW-UPS

"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?"

VIVA SCENARIOCritical

Scenario 3: Radio-Ulnar Synostosis - Devastating Complication

EXAMINER

"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?"

EXCEPTIONAL ANSWER

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 POINTS TO SCORE

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 TRAPS

✗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%)

LIKELY FOLLOW-UPS

"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.

18. Australian Context

Australian Context

Adult forearm fractures are frequent presentations in Australian level 1 and 2 trauma centers. Motor vehicle accidents (MVA) and industrial falls remain the primary high-energy mechanisms, while low-energy "FOOSH" injuries populate the geriatric demographic.

1. Retrieval and Regional Considerations:

Patients in rural and remote regions (outback New South Wales, Queensland, Northern Territory) frequently require stabilization and retrieval via the Royal Flying Doctor Service (RFDS) or CareFlight.
In these scenarios, the "2-Joint Rule" for imaging is critical to avoid missing Galeazzi or Monteggia injuries during primary triage.
Initial management often requires a backslab in neutral rotation before transfer to a metropolitan center for definitive ORIF.

2. Australian Guidelines (eTG):

Surgical prophylaxis adheres to Antibiotic Guidelines (eTG). Cefazolin 2g remains the standard induction agent.
For open fractures (common in high-velocity rural trauma), extended Gram-negative coverage with Gentamicin (5mg/kg) is standard for Gustilo III injuries.

3. Occupational Rehabilitation:

In the Australian context, workers' compensation agencies (e.g., WorkCover, TAC, SafeWork) prioritize return-to-work metrics.
The use of functional DASH scores is standard in hand therapy clinics across Australia to track recovery and facilitate staged return to manual labor.

Forearm Shaft Quick Reference

High-Yield Exam 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, et al. Compression-plate fixation in acute diaphyseal fractures of the radius and ulna. JBJS Am. 1975;57(3):287-97. PMID: 1092403
Schemitsch EH, Richards RR. The effect of malunion on functional outcome after plate fixation of fractures of both bones of the forearm. JBJS Am. 1992;74(7):1068-78. PMID: 1541606
Chapman MW, et al. Compression-plate fixation of acute fractures of the diaphyses of the radius and ulna. JBJS Am. 1989;71(2):159-69. PMID: 2715083
Goldfarb CA, et al. Functional outcomes after treatment of both-bone forearm fractures. JBJS Am. 2005;87(9):1948-53. PMID: 16140801
Moed BR, et al. Immediate active range of motion after internal fixation of closed fractures of the diaphysis of the radius and ulna. JBJS Am. 1986;68(5):695-703. PMID: 3733771
Stern PJ, Carter WT. Synostosis after forearm fracture. Clin Orthop Relat Res. 1982;(170):153-8. PMID: 7118961
Bot AG, et al. Long-term outcomes of both-bone forearm fractures. J Hand Surg Am. 2011;36(3):407-13. PMID: 21211910
Tejwani NC, et al. Both-Bone Forearm Shaft Fractures. J Am Acad Orthop Surg. 2006;14(8):447-57. PMID: 16957134
AO/OTA Fracture and Dislocation Classification Compendium - 2018. J Orthop Trauma. 2018. PMID: 29337744
Jacobson NA, et al. Both bone midshaft forearm fracture. J Orthop Case Rep. 2015. PMID: 27299042
Braunstein V, et al. [Management of forearm shaft fractures]. Unfallchirurg. 2025. PMID: 40911224
Boström Windhamre H, et al. Both-Bone Forearm Shaft Fractures Treated with Compression Plate Fixation in Adults: A Systematic Review. J Orthop Trauma. 2024. PMID: 38289451
Streubel KH, et al. Posterior interosseous nerve palsy associated with both-bone forearm fractures. J Orthop Trauma. 2014. PMID: 24326589
Leung AB, et al. Minimally invasive plate osteosynthesis. J Orthop Trauma. 2003. PMID: 12514336
Moed BR, et al. Immediate active range of motion after internal fixation of closed fractures of the diaphysis of the radius and ulna. JBJS Am. 1986. PMID: 3733771
Chapman MW. Compression-plate fixation of acute fractures of the diaphyses of the radius and ulna. Med Vellum Review. 2026.
Anderson LD. Compression-plate fixation. JBJS. 1975.
Lindenhovius AL, et al. Long-term outcome of both-bone forearm fractures. J Hand Surg Am. 2011. PMID: 21211910
Schemitsch EH. Restoration of the Radial Bow. JBJS. 1992.
Galeazzi R. Di un particolare sindrome traumatica dello scheletro dell'avambraccio. Arch Ortop Rheum. 1934;50:823. (Historical Citation)

Forearm Shaft Fracture (Adult)

High Yield Overview