BOTH-BONE FOREARM FRACTURES - ROTATION ESSENTIAL
Anatomic Reduction Required | Plate Fixation Standard | Compartment Syndrome Risk
LOCATION-BASED APPROACH
Critical Must-Knows
- Anatomic reduction essential - malunion impairs rotation
- Plate both bones - 3.5mm LC-DCP or locking plates
- Minimum 6 cortices each side of fracture (3 screws)
- Restore radial bow - critical for supination
- Compartment syndrome risk - high energy mechanism
Examiner's Pearls
- "Radial bow is at junction of proximal and middle thirds - must restore
- "Plate radius on volar (Thompson) surface - less symptomatic
- "Plate ulna on dorsal/tension surface
- "Loss of just 10 degrees of rotation = significant functional deficit
Critical Both-Bone Forearm Exam Points
Anatomic Reduction
Non-anatomic reduction impairs rotation. Unlike other long bone fractures, the forearm requires anatomic reduction to restore rotation. Even 10° angulation or 10° rotation malalignment significantly reduces supination/pronation.
Radial Bow
Restore the radial bow - the normal curve of the radius is critical for supination. Maximum bow at junction of proximal and middle thirds. Loss of bow = loss of rotation, especially supination.
Plate Fixation Standard
Both bones require plating in adults. Standard is 3.5mm LC-DCP or locking plates. Minimum 6 cortices (3 screws) each side of fracture. May need larger construct for comminution.
Compartment Syndrome
High risk with both-bone fractures, especially high-energy. Maintain high index of suspicion. Pain with passive finger extension, tense compartments = emergency fasciotomy.
Quick Decision Guide
| Pattern | Key Consideration | Treatment |
|---|---|---|
| Adult both-bone fracture | Standard displaced fracture | ORIF both bones with 3.5mm plates |
| Simple transverse pattern | Compression achievable | LC-DCP with lag and compression |
| Comminuted pattern | Cannot compress | Bridge plating, may need longer construct |
| Open fracture | Soft tissue compromise | Urgent debridement, internal or external fixation |
| Segmental pattern | Multiple fractures one bone | Long plate spanning all fractures |
| Ipsilateral upper limb injury | Floating elbow/wrist | Prioritize forearm stability |
| Pediatric both-bone | Growth plate considerations | Often closed reduction, casting acceptable |
FOREARM - Fixation Principles
Memory Hook:FOREARM fixation requires attention to every detail
BOW - Radial Bow Restoration
Memory Hook:The radial BOW is essential for supination
PLATES - Placement Principles
Memory Hook:PLATES positioned correctly prevent complications
COMPARTMENTS - Syndrome Recognition
Memory Hook:COMPARTMENTS syndrome is a clinical diagnosis requiring immediate fasciotomy
Overview and Epidemiology
Both-bone forearm fractures in adults are typically high-energy injuries requiring operative fixation. The forearm is unique because it functions as a paired bone articulated joint - both bones rotate around each other, and any disruption of anatomy impairs this function.
Mechanism of injury:
- Direct trauma - blow to forearm
- Often comminuted at impact site
- Industrial injuries, assault
- Indirect trauma - fall on outstretched hand
- Rotational component common
- Motor vehicle accidents
- High-energy mechanisms predominate - MVA, falls from height, sport
Forearm as a Joint
The forearm functions as a paired rotational joint - the radius rotates around the ulna through approximately 150° arc. This requires intact proximal radioulnar joint (PRUJ), interosseous membrane (IOM), and distal radioulnar joint (DRUJ). Both-bone fractures disrupt this mechanism.
Associated injuries:
- Compartment syndrome (high risk)
- Neurovascular injury
- Ipsilateral elbow injury (floating elbow)
- Ipsilateral wrist injury (floating wrist)
- Associated hand injuries
Anatomy and Biomechanics
Deforming Muscle Forces:
- Proximal Radius (Supinator/Biceps): Supinated and flexed
- Middle Radius (Pronator Teres): Pronated (if distal to insertion)
- Distal Radius (Pronator Quadratus): Pronated
Radial anatomy:
- Radial head - articulates with capitellum and PRUJ
- Radial tuberosity - biceps insertion
- Radial bow - maximum curvature at junction proximal/middle thirds
- Lateral surface - covered by wrist extensors
- Volar surface - FPL origin, plate placement area
Ulnar anatomy:
- Olecranon - triceps insertion
- Coronoid - anterior buttress
- Shaft - relatively straight, triangular cross-section
- Subcutaneous border - medial, palpable throughout
- Dorsal surface - ECU groove, plate placement area
Key relationships:
- Interosseous membrane (IOM) - connects radius to ulna
- PRUJ - proximal radioulnar joint
- DRUJ - distal radioulnar joint
- Interosseous space - maintained for rotation
Radial Bow Significance
The radial bow is the normal lateral convexity of the radius. Maximum bow is at the junction of proximal and middle thirds. Loss of even 10% of radial bow can result in loss of supination. Always compare to contralateral side and use pre-contoured plates.
Biomechanics of rotation:
- Normal supination/pronation: 75°/75° approximately
- Radius rotates around relatively fixed ulna
- Rotation occurs at PRUJ, DRUJ, and through IOM
- Loss of 10° rotation malalignment = significant functional loss
Surgical anatomy - approaches:
- Thompson (dorsolateral radius) - between ECRB and EPL
- Henry (volar radius) - between BR and PT/FCR
- Ulnar approach - along subcutaneous border
Classification Systems
Location Classification
| Location | Radius | Ulna |
|---|---|---|
| Proximal third | Near radial head/tuberosity | Near olecranon/coronoid |
| Middle third | Shaft - most common | Shaft |
| Distal third | Near wrist | Near DRUJ |
Considerations by location:
- Proximal: risk of PIN, need different approach
- Middle: standard Thompson + ulnar approach
- Distal: consider associated DRUJ/wrist injury
Location determines surgical approach and implant selection.
Clinical Presentation and Assessment
History:
- Mechanism (high vs low energy)
- Time of injury
- Open wound (assume open until proven otherwise)
- Associated injuries
- Hand dominance, occupation
Physical examination:
Physical Examination Findings
| Finding | Significance | Action |
|---|---|---|
| Deformity | Displaced fracture | Document, assess NV, reduce |
| Open wound | Open fracture | Antibiotics, urgent surgery |
| Tense compartments | Compartment syndrome | Emergency fasciotomy |
| Pain with passive stretch | Impending compartment syndrome | Serial monitoring or fasciotomy |
| Vascular deficit | Arterial injury | Urgent reduction, angiography/repair |
| Nerve deficit (PIN, median, ulnar) | Nerve injury/compression | Document pre-op, may resolve with reduction |
| Ipsilateral elbow/wrist injury | Floating segment | Address all injuries |
Compartment syndrome assessment:
5 Ps - Late Signs
The classic 5 Ps (Pain, Pallor, Pulselessness, Paralysis, Paresthesia) are late signs. Early compartment syndrome: Pain out of proportion and pain with passive stretch of fingers. Don't wait for all 5 Ps - fasciotomy needed urgently.
Key examination points:
- Compartment assessment - volar and dorsal
- Neurovascular status - PIN, median, ulnar nerves; radial and ulnar pulses
- Skin integrity - open wound assessment
- Associated injuries - elbow, wrist, hand
- Soft tissue swelling - predictor of complications
Investigations
Radiographic assessment:
Standard views:
- AP forearm - entire forearm including elbow and wrist
- Lateral forearm - true lateral
- Dedicated elbow views - AP and lateral if proximal injury
- Dedicated wrist views - AP and lateral if distal injury
Joint Above and Below
Always image the joint above and below. A forearm fracture series must include adequate views of the elbow and wrist to exclude Monteggia (proximal) or Galeazzi (distal) variants.
Radiographic assessment checklist:
- Fracture location and pattern (both bones)
- Degree of comminution
- Angulation and displacement
- Radial head congruent with capitellum?
- DRUJ congruent?
- Shortening present?
CT imaging:
- Rarely indicated for shaft fractures
- May help for complex articular extension
- 3D reconstruction for difficult patterns
Compartment pressure monitoring:
- If clinical suspicion
- Absolute pressure greater than 30mmHg concerning
- Delta pressure (Diastolic - Compartment) less than 30mmHg = fasciotomy
Management Algorithm
Definitive Management
Non-operative management:
- Isolated, undisplaced fractures (rare)
- Non-ambulatory patients
- Significant medical comorbidities precluding surgery
- Patient refusal
- Long arm cast, elbow 90°, neutral rotation
- Weekly X-rays for first 3 weeks
- Any displacement = convert to operative
- Expect prolonged immobilization and stiffness
Conservative Treatment Rarely Indicated
Non-operative treatment is rarely indicated for adult both-bone forearm fractures. Non-anatomic healing leads to loss of rotation and poor function. Operative fixation is the standard of care.
Surgical Technique
Surgical Approaches
Radius - Thompson (Dorsolateral):
- Incision: lateral epicondyle to Lister's tubercle
- Interval: ECRB and EPL (proximal), EPB/APL (distal)
- Danger: PIN crosses at level of radial head
- Pros: excellent visualization, less symptomatic plate
Radius - Henry (Volar):
- Incision: lateral to biceps tendon to radial styloid
- Interval: BR/PT and FCR/radial artery
- Pros: safer for proximal third (PIN protected)
- Cons: plate may be more prominent
Ulna:
- Incision along subcutaneous border
- Directly onto bone (ECU/FCU interval)
- Minimal soft tissue dissection
- Plate on dorsal tension surface
Thompson vs Henry
Thompson (dorsolateral) is preferred for middle and distal radius - plate less symptomatic, good exposure. Henry (volar) is safer for proximal third - PIN is protected as it crosses deeper in the supinator. Choose approach based on fracture level.
Complications
Complications of Both-Bone Forearm Fracture Treatment
| Complication | Incidence | Management |
|---|---|---|
| Compartment syndrome | 2-5% | Emergency fasciotomy |
| Malunion | 5-10% | Corrective osteotomy if symptomatic |
| Nonunion | 2-5% | Revision fixation, bone graft |
| Synostosis | 3-5% | Excision if mature, interposition |
| Infection | 1-3% closed, higher open | Debridement, antibiotics |
| Nerve injury (PIN most common) | 2-5% | Usually neurapraxia, observation |
| Hardware failure | 2-3% | Revision with bone graft |
| Refracture (after plate removal) | 5-10% | Protected activity, avoid early removal |
Compartment syndrome:
- Most critical early complication
- High-energy injuries at highest risk
- Pain with passive finger extension is early sign
- Emergency fasciotomy - both volar and dorsal compartments
Malunion:
- Loss of rotation most functionally limiting
- Greater than 10° angulation or rotation = significant deficit
- Corrective osteotomy with bone graft if symptomatic
Synostosis:
- Abnormal bone bridge between radius and ulna
- Risk factors: high energy, single incision, head injury
- Prevention: orthogonal plating (90° apart), avoid IOM damage
- Treatment: excision when mature (greater than 1 year), interposition material
Refracture After Plate Removal
Refracture can occur after plate removal, especially if removed early. Recommend leaving plates in place unless symptomatic. If removal needed, wait 18-24 months post-op, and protect with splint and activity restriction for 6-8 weeks after removal.
Postoperative Care and Rehabilitation
Postoperative protocol:
- Posterior splint for comfort
- Elevation
- Finger motion immediately
- Monitor for compartment syndrome
- Wound check day 2 and 5-7
- Begin active ROM elbow and wrist
- Gentle active supination/pronation
- Wean from splint
- Light functional use
- Progressive active ROM
- Expect near full ROM by 6 weeks
- No resistance/lifting
- Light activities of daily living
- Begin gentle strengthening
- Progressive loading
- Return to light work
- X-ray at 6 weeks to confirm union
- Full strengthening
- Return to sport/heavy work
- Full union expected
- Final ROM assessment
Key rehabilitation principles:
- Early motion critical - prevents stiffness
- Stable fixation allows early motion
- Focus on rotation (supination/pronation)
- Progressive loading after union confirmed
- Final ROM assessment at 6 months
Union Timeline
Both-bone forearm fractures typically unite in 12-16 weeks. Confirm radiographic union before allowing heavy activities. Delayed union more common with comminution, open fractures, and smoking.
Outcomes and Prognosis
Expected outcomes:
| Measure | Expectation |
|---|---|
| Union | 90-95% primary union |
| ROM | Less than 10-20° loss supination/pronation |
| Strength | 85-95% of contralateral |
| Function | DASH scores typically excellent |
| Return to work | 3-6 months most patients |
Prognostic factors:
- Open vs closed (open = worse outcomes)
- Energy of injury
- Quality of reduction
- Bone quality
- Patient compliance
- Smoking status
Functional Rotation
Most activities of daily living require approximately 50° supination and 50° pronation. Loss of rotation up to 20° is often well-tolerated functionally. Greater loss typically symptomatic and may warrant corrective surgery.
Evidence Base
- Compression plating of forearm fractures produced 97% union rate with excellent functional outcomes. Established compression plating as standard treatment for adult both-bone fractures.
- Loss of radial bow significantly impairs supination. Even 10% loss of bow can reduce supination by 20-30%. Restoration of radial bow is critical.
- Immediate internal fixation of open forearm fractures (Type I, II) after debridement produced good results without increased infection. Type III fractures had higher complications.
- Locking plates did not show superior outcomes to conventional plates for forearm fractures. Both achieved high union rates. Locking plates may have role in osteoporotic bone.
- Refracture after forearm plate removal occurred in approximately 4-25% depending on timing and technique. Earlier removal and larger screw holes increased risk.
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Closed Both-Bone Forearm Fracture
"A 35-year-old man falls from a motorcycle at low speed. He has a closed both-bone forearm fracture in the mid-shaft. X-rays show transverse fractures of both radius and ulna with 100% displacement. How would you manage this injury?"
Thank you. This gentleman has sustained **closed displaced both-bone forearm fractures** from a motorcycle accident. Despite being described as low speed, this is still a significant energy mechanism.
Initial Assessment:
- Neurovascular examination - radial/ulnar pulses, PIN, median, ulnar nerve function
- Compartment assessment - forearm swelling, tension, pain with passive finger stretch
- Skin integrity - confirm truly closed
- Associated injuries - examine entire limb, joint above and below
Imaging:
I would ensure the X-rays include **adequate views of elbow and wrist** to exclude associated injuries (Monteggia/Galeazzi variants).
Initial Management:
- Reduce deformity and splint in comfortable position
- Analgesia
- Serial neurovascular and compartment checks
Definitive Management - ORIF:
Both-bone forearm fractures in adults require **operative fixation** to restore anatomy and rotation.
Surgical Plan:
- Timing: Within 24-48 hours unless compartment syndrome develops
- Approaches:
- Radius: **Thompson (dorsolateral)** approach - mid-shaft fracture, good access
- Ulna: direct approach over subcutaneous border
- Fixation:
- **3.5mm LC-DCP** plates on both bones
- Minimum **6 cortices** each side of fracture
- Transverse pattern - direct **compression** with eccentric screws
- Restore **radial bow** - contour plate to match
- Plate positioning:
- Radius: volar (Thompson) surface
- Ulna: dorsal/tension surface
- **Orthogonal (90° apart)** to reduce synostosis risk
Technical Points:
- I would typically fix the **radius first** as it's more technically demanding
- Ensure anatomic reduction - check rotation by matching cortical diameters
- Confirm smooth forearm rotation intraoperatively
Postoperative:
- Splint for comfort initially
- Early active ROM within first week
- Expect union by 12-16 weeks
Scenario 2: Open Forearm Fracture
"A 28-year-old construction worker has his forearm caught in machinery. He has a Gustilo Type II open both-bone forearm fracture with a 3cm wound over the volar forearm. The fractures are at different levels. What is your management?"
Thank you. This is a **Gustilo Type II open both-bone forearm fracture** from a high-energy industrial mechanism. This requires urgent surgical management.
Immediate Management:
- **Antibiotics** - cefazolin 2g IV within 1 hour of injury
- **Tetanus** prophylaxis
- **Neurovascular assessment** - document in detail pre-operatively
- **Photo documentation** of wound
- **Gross debris removal** and moist saline dressing
- **Splint** in position of comfort
- **Do not probe** the wound further in ED
Rationale: Early antibiotics are the most important factor in preventing infection. Thorough debridement in theater is the key to success.
Surgical Plan:
- **Thorough Debridement:** Extend wounds if necessary. Excise all non-viable tissue. Deliver fracture ends and clean medullary canal. Pulse lavage.
- **Fixation:** I would perform **acute internal fixation** with plates after debridement. Evidence supports this for Type I, II, and IIIA fractures (Chapman). It provides stability for soft tissue healing.
- **Closure:** Loose approximation or delayed primary closure if swelling concerns. Do not close under tension.
Postoperative:
- Continue antibiotics 24-48 hours post-op (Type II)
- Daily wound assessment
- Splint for protection
- ROM when wound allows
Scenario 3: Compartment Syndrome
"Six hours after plating a both-bone forearm fracture, the nurse calls you because the patient is in severe pain despite adequate analgesia. His fingers are swollen and he has severe pain with passive finger extension. What do you do?"
Thank you. This clinical picture is highly concerning for acute compartment syndrome of the forearm. This is an orthopaedic emergency requiring immediate action.
Immediate Assessment (at bedside now):
- Pain out of proportion to expected - key early finding
- Pain with passive stretch of fingers - most sensitive sign
- Assess compartments - volar and dorsal forearm tension
- Check neurovascular status - but don't wait for deficits
- Remove any constrictive dressings/splints
Key Point: The 5 Ps (Pain, Pallor, Pulselessness, Paralysis, Paresthesia) are late signs. Do not wait for all of these. Pain with passive stretch and pain out of proportion are early indicators requiring action.
Decision: Given the clinical findings - severe pain with passive stretch, occurring 6 hours post high-energy injury and surgery - this is compartment syndrome until proven otherwise. I would:
- Immediately return to theater for emergency fasciotomy
- Do not delay for compartment pressure measurements if clinical picture is clear
- Notify theater and anesthesia urgently
If Pressure Monitoring Needed (equivocal cases):
- Absolute pressure greater than 30mmHg concerning
- Delta pressure (Diastolic BP - Compartment pressure) less than 30mmHg = fasciotomy
Emergency Fasciotomy - Both Compartments:
Volar Release:
- Carpal tunnel release (extend distally)
- Extend proximally along forearm
- Release superficial and deep flexor compartments
- Release mobile wad (BR, ECRL, ECRB)
Dorsal Release:
- Straight incision over dorsal forearm
- Release extensor compartments
Technical Points:
- Full-length incisions
- Fasciotomy must be complete - superficial and deep compartments
- Inspect muscle viability - pink, contractile, bleeding = viable
- Excise clearly necrotic muscle
- Leave wounds open - do not attempt primary closure
- Apply wet dressings or VAC
Postoperative:
- Return to theater in 48-72 hours
- Reassess muscle viability
- Delayed primary closure, skin graft, or VAC if needed
- Document timing of recognition and treatment (medicolegal)
MCQ Practice Points
Reduction Question
Q: Why is anatomic reduction essential in both-bone forearm fractures? A: The forearm is a paired rotational joint - radius rotates around ulna. Even 10° of angulation or rotational malunion significantly reduces supination and pronation. Unlike other diaphyseal fractures, the forearm does not tolerate malunion.
Fixation Question
Q: What is the minimum fixation for both-bone forearm fractures? A: 3.5mm plates with minimum 6 cortices (3 screws) each side of the fracture for each bone. Eight cortices (4 screws) provides more security and is often preferred.
Anatomy Question
Q: Where is the maximum radial bow and why is it important? A: Maximum bow is at the junction of proximal and middle thirds of the radius. The bow is critical for supination - loss of radial bow results in loss of supination. Must restore with contoured plate.
Approach Question
Q: What is the danger with Thompson (dorsolateral) approach to the radius? A: The posterior interosseous nerve (PIN) crosses at the level of the radial head (approximately 4cm from lateral epicondyle). Protect by supinating forearm and staying anterior to supinator. Consider Henry approach for very proximal fractures.
Complications Question
Q: How do you reduce the risk of radioulnar synostosis? A: Use orthogonal plating (plates 90° apart), avoid single incision for both bones, meticulous soft tissue handling, preserve interosseous membrane, and avoid high-energy mechanisms (not modifiable).
Australian Context
Epidemiology:
- Common with motorcycle accidents
- Industrial injuries (machinery, farming)
- Sports injuries (cycling, contact sports)
- Falls from height (construction)
Management considerations:
- Emergency fasciotomy: 30106
- Most hospitals equipped for standard plate fixation
Transfer considerations:
- Open fractures to trauma centres
- Gustilo IIIB/C require plastic surgery capability
- Compartment syndrome managed at presenting hospital
Exam Context
Be prepared to discuss surgical approaches, fixation principles (especially radial bow restoration), compartment syndrome recognition and management, and open fracture protocols. Both-bone fractures are common viva topics testing fundamental principles.
BOTH-BONE FOREARM FRACTURES
High-Yield Exam Summary
KEY PRINCIPLES
- •Anatomic reduction essential - non-anatomic = loss of rotation
- •Plate both bones in adults
- •Restore radial bow (max at proximal-middle junction)
- •Orthogonal plating (90° apart) reduces synostosis
FIXATION STANDARD
- •3.5mm LC-DCP or locking plates
- •Minimum 6 cortices (3 screws) each side
- •8 cortices (4 screws) preferred
- •Bicortical screw purchase
SURGICAL APPROACHES
- •Radius: Thompson (dorsolateral) for mid/distal
- •Radius: Henry (volar) safer for proximal (PIN protected)
- •Ulna: Direct over subcutaneous border
- •PIN danger zone: 4cm from lateral epicondyle
PLATE POSITIONING
- •Radius: volar (Thompson) surface - less symptomatic
- •Ulna: dorsal tension surface
- •90° apart to reduce synostosis risk
- •Contour plate to restore radial bow
COMPARTMENT SYNDROME
- •Pain with passive finger stretch = early sign
- •5 Ps are LATE signs - don't wait
- •Emergency fasciotomy if clinical suspicion
- •Release volar AND dorsal compartments
OPEN FRACTURES
- •Antibiotics within 1 hour
- •Thorough debridement
- •Type I/II: internal fixation appropriate
- •Type III: consider external fixation initially