High Yield Overview

DIE-PUNCH FRACTURES

Lunate Facet Depression | Axial Load Mechanism | Articular Restoration Critical

Lunate FacetArticular surface involved

Axial LoadDirect impact mechanism

2mmMaximum acceptable step-off

ORIFStandard treatment approach

SANDER & MEDOFF CLASSIFICATION

Type I

PatternSimple depression without comminution

TreatmentElevation and K-wire/screw fixation

Type II

PatternDepression with split component

TreatmentFragment-specific fixation required

Type III

PatternComminuted with metaphyseal extension

TreatmentComplex reconstruction, consider bone graft

Critical Must-Knows

Lunate facet is the concave articular surface articulating with the lunate
Axial load drives lunate into radius like a punch into a die
CT scan essential - plain radiographs underestimate depression depth
Step-off greater than 2mm predicts post-traumatic arthritis
Fragment-specific fixation with subchondral support is treatment goal

Examiner's Pearls

"
Die-punch is the 'hidden fracture' - easily missed on plain films
"
Always get CT for any high-energy distal radius fracture
"
Volar approach may miss dorsal die-punch - consider dorsal access
"
Bone graft often needed for metaphyseal void after elevation

Clinical Imaging

Imaging Gallery

6-panel die-punch fracture pre-operative imaging with X-rays, CT, and 3D reconstruction — Die-Punch Fracture Pre-operative Imaging. (A) PA radiograph showing subtle articular incongruity. (B) Lateral showing dorsal tilt. (C) Axial CT showing fragment. (D) Coronal CT demonstrating lunate facet depression. (E) Sagittal CT showing fragment displacement. (F) 3D CT dorsal view for surgical planning. CT with sagittal reconstructions is MANDATORY - plain films significantly underestimate depression.Credit: Xu et al., BMC Surg 2023, PMC10290794, CC BY 4.0

4-panel post-operative imaging showing combined dorsal and volar plate fixation with long-term follow-up — Combined Approach Fixation and Outcome. (A,B) Immediate post-op AP and lateral showing combined dorsal plate + VLP with K-wires for die-punch fragment support. (C,D) 30-month follow-up after hardware removal demonstrating anatomic union and articular congruity restoration.Credit: Xu et al., BMC Surg 2023, PMC10290794, CC BY 4.0

High-Yield Die-Punch Fracture Exam Points

Mechanism Understanding

THE DIE ANALOGY: The lunate acts as the "punch" and the radius as the "die" - axial load drives the hard lunate bone into the softer cancellous bone of the lunate facet, creating a depressed articular fragment. This is most common in high-energy injuries.

CT is Mandatory

Plain radiographs significantly underestimate the degree of articular depression. CT with sagittal reconstructions is essential for surgical planning. Look for associated scapholunate ligament injury on axial cuts.

Step-Off Threshold

Greater than 2mm step-off of the articular surface is the threshold for surgical intervention. Studies show this predicts post-traumatic arthritis. Aim for anatomic reduction with step-off under 1mm.

Surgical Approach

Dorsal approach often needed to visualize and elevate die-punch fragments. Standard volar plating may miss dorsal depression. Fragment-specific fixation with K-wires, screws, or dorsal plates provides subchondral support.

At a Glance: Die-Punch Fracture Management

Fracture Pattern	Displacement	Management	Key Consideration
Simple depression	Under 2mm step-off	Non-operative with close monitoring	CT follow-up at 2 weeks to assess
Simple depression	Over 2mm step-off	ORIF - elevation and fixation	May need bone graft for void
Depression with split	Any displacement	Fragment-specific fixation	Address both components
Comminuted pattern	Significant depression	Complex reconstruction	Consider external fixation plus ORIF
Associated SL injury	Variable	Address ligament after bony fixation	Assess with arthroscopy if uncertain

Mnemonic

DIE-PUNCH - Key Fracture Features

Depression

Articular surface is depressed, not displaced

Impact mechanism

Axial load drives lunate into radius

Elevation needed

Surgical goal is to elevate depressed fragment

Plain films miss it

CT is essential for diagnosis and planning

Under 2mm goal

Target step-off less than 2mm for good outcome

Need bone graft

Metaphyseal void often requires grafting

CT mandatory

Always get CT for any suspected die-punch

High energy

Usually results from significant axial load

Memory Hook:DIE-PUNCH tells you exactly what it is - the lunate punches into the radial die

Mnemonic

FACET - Lunate Facet Assessment

Facet location

Lunate facet is ulnar half of distal radius articular surface

Articular congruity

Assess step-off and gap on CT sagittal cuts

CT essential

Sagittal and coronal reconstructions for planning

Evaluate scapholunate

Associated SL injury in high-energy mechanism

Two millimeter threshold

Over 2mm step-off requires surgical intervention

Memory Hook:FACET reminds you to focus on the lunate FACET and CT assessment

Mnemonic

GRAFT - When to Use Bone Graft

Gap present

Metaphyseal void after fragment elevation

Reduced stability

Subchondral support needed for fragment

Autograft or substitute

Iliac crest, distal radius, or synthetic

Fill the void

Prevents secondary collapse of elevated fragment

Timing at surgery

Graft placed immediately after elevation

Memory Hook:GRAFT reminds you when and why bone graft is needed after elevation

Overview and Epidemiology

Definition

Die-punch fractures are depressed articular fractures of the lunate facet of the distal radius. The name derives from metalworking terminology - the lunate bone acts as the "punch" and the radius as the "die" when axial force is applied.

Epidemiology

Incidence: Occur in approximately 20-30% of intra-articular distal radius fractures
Age distribution: Bimodal - young adults with high-energy trauma and elderly with osteoporotic bone
Mechanism: High-energy axial loading (falls from height, motor vehicle accidents)
Associated injuries: Often part of complex distal radius fracture patterns

Clinical Significance

The lunate facet transmits 60% of axial load across the wrist. Depression of this articular surface leads to:

Altered radiocarpal biomechanics
Concentrated stress at step-off margins
Progressive cartilage degeneration
Post-traumatic radiocarpal arthritis

Intraoperative photo of dorsal approach showing die-punch bone fragments — Dorsal Approach for Die-Punch Fragment Visualization. Intraoperative view showing dorsal capsulotomy with direct visualization of depressed die-punch bone fragments (dark areas in wound). The dorsal approach allows direct fragment elevation, bone grafting, and dorsal plate application for large dorsal fragments. Combined with VLP for optimal stability.Credit: Xu et al., BMC Surg 2023, PMC10290794, CC BY 4.0

Die-punch fractures represent a significant subset of distal radius fractures that require careful evaluation.

Anatomy/Biomechanics

Articular Anatomy

Lunate Facet

Location: Ulnar half of distal radius articular surface
Shape: Concave in both sagittal and coronal planes
Articulation: Articulates with proximal pole of lunate
Load transmission: Carries approximately 60% of wrist axial load
Sigmoid notch: Forms medial border, articulates with ulnar head

Scaphoid Facet

Location: Radial half of distal radius articular surface
Shape: Triangular, slightly convex in sagittal plane
Articulation: Articulates with proximal scaphoid pole
Interfacet ridge: Separates scaphoid and lunate facets

Subchondral Architecture

The cancellous bone beneath the lunate facet is organized in specific patterns:

Subchondral plate: Dense cortical layer supporting cartilage
Trabecular network: Oriented to resist axial compression
Metaphyseal zone: Transition area with less dense bone
Watershed zone: Area of reduced vascularity prone to necrosis

Blood Supply

Arterial Supply

Radial artery: Supplies volar and dorsal surfaces
Ulnar artery: Contributes to ulnar aspect
Anterior interosseous artery: Supplies palmar metaphysis
Posterior interosseous artery: Dorsal metaphyseal supply

Periosteal Network

Extensive anastomotic network around metaphysis
Generally good healing potential
Comminuted fragments may have compromised supply

Relevant Soft Tissue Anatomy

Volar Structures

Volar radiocarpal ligaments: May be disrupted in severe injuries
Pronator quadratus: Overlies volar surface
Flexor tendons: FCR passes radially, FPL centrally

Dorsal Structures

Extensor compartments: Pass dorsally over radius
Dorsal radiocarpal ligaments: Provide carpal stability
Lister's tubercle: Landmark for EPL tendon

Understanding the anatomy is essential for planning surgical approach and fixation strategy.

Classification Systems

Sander and Medoff Classification

This is the most commonly used classification specific to die-punch fractures:

Type I - Simple Depression

Central articular depression without significant comminution
Single depressed fragment
Intact peripheral rim
Treatment: Elevation with K-wire or screw fixation

Type II - Depression with Split

Depressed fragment with associated split component
Sagittal or coronal split extending from depression
More unstable than Type I
Treatment: Fragment-specific fixation addressing both components

Type III - Comminuted

Multiple comminuted fragments
Metaphyseal extension of fracture
Associated dorsal or volar cortical disruption
Treatment: Complex reconstruction, often requires bone graft

The classification guides surgical approach and fixation strategy.

Classification Comparison

Classification	Type	Key Feature	Stability
Sander-Medoff	Type I	Simple central depression	Relatively stable
Sander-Medoff	Type II	Depression with split	Unstable
Sander-Medoff	Type III	Comminuted with extension	Very unstable
Melone	Type II	Classic die-punch pattern	Variable - IIA stable, IIB unstable
AO/OTA	C2/C3	Complete articular fracture	Unstable

Classification guides surgical planning and helps predict outcomes.

Clinical Assessment

History

Mechanism of Injury

High-energy trauma: Fall from height, motor vehicle accident, motorcycle crash
Sports injuries: Wakeboarding, snowboarding, contact sports with axial load
Direct axial load: Distinguishes from rotational mechanisms

Key History Points

Energy of injury (height of fall, vehicle speed)
Position of wrist at impact
Associated injuries suggesting polytrauma
Hand dominance and occupational demands
Pre-existing wrist pathology

Physical Examination

Inspection

Swelling over distal radius - often less dramatic than displaced fractures
Minimal deformity compared to displaced fracture patterns
Ecchymosis - may be delayed

Palpation

Diffuse tenderness over distal radius
Point tenderness over dorsal lunate facet
Assess for associated DRUJ tenderness

Range of Motion

Significantly limited by pain in acute setting
Loss of forearm rotation suggests DRUJ involvement

Neurovascular Assessment

Median nerve: Check sensation in radial 3.5 digits
Carpal tunnel symptoms: May develop with swelling
Radial pulse: Usually preserved
Capillary refill: Assess digital perfusion

High-Energy Mechanism Red Flags

Any high-energy mechanism warrants thorough polytrauma evaluation:

Cervical spine assessment
Ipsilateral upper extremity examination (elbow, shoulder)
Chest and abdominal examination
Associated carpal injuries (scapholunate, TFCC)

Special Tests

Watson Test (Scaphoid Shift)

Assess for scapholunate ligament injury
Common association in high-energy wrist trauma

DRUJ Stability

Piano key test for ulnar head stability
Compare to contralateral side

Grip Strength

Usually not assessable acutely due to pain
Baseline for rehabilitation assessment

Clinical examination alone is insufficient for diagnosis - imaging is essential.

Investigations

Plain Radiographs

Standard Views

PA view: May show subtle articular irregularity
Lateral view: Can reveal dorsal cortical comminution
Oblique views: Additional perspective on fracture lines

Radiographic Signs

Double cortical sign: Overlapping depressed and non-depressed articular surfaces
Loss of normal concavity: Lunate facet appears flattened
Associated fracture lines: Sagittal or coronal splits

Limitations

Underestimates depression: Often by several millimeters
Misses pure articular injuries: Depression without cortical break
Cannot assess comminution: Overlapping fragments obscure detail

CT Scanning

Indications (MANDATORY for Die-Punch)

Any suspected articular involvement
High-energy mechanism
Preoperative planning for all operative cases
Assessment of reduction post-operatively

Protocol

Slice thickness: 1mm or less
Reconstructions: Sagittal, coronal, and 3D
Compare contralateral: For subtle depressions

Key CT Findings

Step-off measurement: Quantify articular incongruity
Fragment size: Assess for fixation options
Comminution degree: Plan for bone graft need
Dorsal vs volar location: Determines surgical approach

MRI

Indications

Suspected ligamentous injury
Scapholunate assessment when arthroscopy unavailable
TFCC evaluation

Findings

Ligament disruption
Bone marrow edema pattern
Cartilage injury assessment

Arthroscopy

Diagnostic Role

Gold standard for ligament assessment
Assess articular surface reduction
Evaluate TFCC and intercarpal ligaments

Therapeutic Role

Assist reduction visualization
Debridement of loose bodies
Ligament repair or pinning

Investigations are summarized in the table below.

Imaging Modalities Comparison

Modality	Role	Advantages	Limitations
Plain X-ray	Initial screening	Quick, available, low cost	Underestimates depression
CT scan	Definitive assessment	Quantifies step-off, shows comminution	Radiation, cost
MRI	Soft tissue evaluation	Ligament and cartilage assessment	Time, cost, less for bone detail
Arthroscopy	Gold standard	Direct visualization, therapeutic	Invasive, requires expertise

CT is mandatory for surgical planning in die-punch fractures.

Management Algorithm

Non-Operative Management

Indications

Articular step-off under 2mm on CT
Minimal displacement of fragments
Low functional demand patient
Medical comorbidities precluding surgery

Protocol

Immobilization

Short arm cast or splint
Duration: 4-6 weeks
Wrist in neutral position

Follow-Up

Week 1-2: Clinical review, repeat radiographs
Week 2-3: CT scan to assess for secondary displacement
Week 4-6: Cast removal, begin ROM exercises

Red Flags for Secondary Surgery

Increasing step-off on follow-up imaging
Development of greater than 2mm displacement
Persistent malposition despite casting

Expected Outcomes

Good results if step-off maintained under 2mm
85% satisfactory outcomes in well-selected patients
Monitor for late collapse requiring delayed intervention

Non-operative management requires vigilant follow-up to detect secondary displacement.

The management algorithm considers both fracture characteristics and patient factors.

Surgical Technique

Dorsal Approach for Die-Punch ORIF

Patient Positioning

Supine with arm table
Tourniquet on upper arm (250-300 mmHg)
Consider tower for traction assistance

Incision and Exposure

Skin Incision

Dorsal longitudinal incision over Lister's tubercle
Approximately 5-6 cm centered on wrist
Extend proximally as needed for fragment access

Deep Dissection

Incise extensor retinaculum between 3rd and 4th compartments
Identify and protect EPL tendon
Retract EDC ulnarly, EPL radially
Elevate capsule as L-shaped flap (ligament-sparing if possible)

Fracture Reduction

Visualization

Direct view of lunate facet articular surface
Assess depression depth and fragment size
Identify any loose osteochondral fragments

Elevation Technique

Use small periosteal elevator or dental pick
Lever fragment through metaphyseal window if needed
Reduce to level of adjacent cartilage
Confirm reduction with direct vision and fluoroscopy

Bone Grafting

Assess metaphyseal void after elevation
Pack cancellous graft (autograft or substitute)
Graft provides subchondral support to prevent collapse

Fixation

K-wire Fixation

1.1 or 1.25 mm K-wires
Capture reduced fragment to metaphysis
Use 2-3 wires for rotational control

Dorsal Plate Fixation

Low-profile dorsal plate
Subchondral screws support articular fragment
Consider locking screws for osteoporotic bone

Closure

Repair capsule
Close retinaculum loosely to allow tendon glide
Standard skin closure
Splint in neutral position

The dorsal approach provides excellent visualization of the die-punch fragment.

Surgical approach should be tailored to the specific fracture pattern and associated injuries.

Complications

Intraoperative Complications

Iatrogenic Fracture

Risk during fragment elevation
Prevention: Gentle technique, use appropriate instruments
Management: Additional fixation if occurs

Screw Penetration

Joint penetration causes arthritis
Prevention: Measure carefully, check with fluoroscopy
Management: Remove and replace with shorter screw

Tendon Injury (Dorsal Approach)

EPL most at risk
Prevention: Careful retraction, protect with vessel loops
Management: Primary repair if recognized

Early Complications

Wound Complications

Infection: 1-3% - IV antibiotics, debridement if deep
Dehiscence: More common dorsally - local wound care
Hematoma: Evacuate if significant

Hardware Problems

K-wire migration: Remove early if backing out
Screw loosening: More common in osteoporotic bone
Loss of reduction: May require revision surgery

Nerve Injury

Median nerve: Carpal tunnel syndrome - decompress if needed
Superficial radial nerve: Paresthesias - usually resolve
PIN (posterior interosseous): Motor weakness - observe

Late Complications

Post-Traumatic Arthritis

Most significant long-term complication
Related to residual step-off greater than 2mm
May require salvage procedures (fusion, arthroplasty)

Malunion

Articular malunion causes arthritis
Extra-articular component may cause functional limitation
Consider corrective osteotomy if symptomatic

Hardware Irritation

Dorsal plates often require removal
Extensor tenosynovitis from prominent hardware
Plan for potential second surgery

CRPS (Complex Regional Pain Syndrome)

Incidence 5-10% after distal radius fractures
Early recognition and treatment essential
Multidisciplinary approach required

Complication Prevention and Management

Complication	Prevention	Management
Articular step-off	Anatomic reduction, CT confirmation	Consider revision if over 2mm
Screw penetration	Careful measurement, fluoroscopy	Remove and replace screw
Infection	Sterile technique, prophylactic antibiotics	Antibiotics, debridement
Hardware irritation	Low-profile implants, proper placement	Hardware removal once healed
CRPS	Early mobilization, pain management	Multidisciplinary team

The key to avoiding complications is anatomic reduction with stable fixation.

Postoperative Care

Immediate Postoperative Care (0-2 Weeks)

Immobilization

Volar resting splint in neutral wrist position
Include forearm in splint
Allow immediate finger motion

Elevation

Hand above heart level when resting
Critical for first 72 hours to reduce swelling
Use pillows or sling when sitting

Pain Management

Multimodal analgesia approach
Ice application for swelling
Elevate extremity

Monitoring

Neurovascular checks every 4 hours initially
Watch for signs of compartment syndrome
Early recognition of infection

Wound Care

Dressing Changes

First change at 48-72 hours by surgeon
Assess wound for healing
K-wire sites need special attention if used

Suture/Staple Removal

10-14 days postoperatively
Earlier if wound well-healed
Apply steri-strips for additional support

Rehabilitation Phases

Phase 1: Protection (Weeks 0-2)

Active finger motion (full fist, extension)
Shoulder and elbow ROM
Edema control

Phase 2: Early Motion (Weeks 2-6)

Begin wrist flexion/extension
Start forearm rotation
Removable splint between exercises
Continue edema management

Phase 3: Progressive Loading (Weeks 6-12)

Progress to functional activities
Light grip strengthening
Discontinue splint (usually at week 6)
Progress to normal ADLs

Phase 4: Return to Function (Weeks 12+)

Progressive strengthening
Sport-specific activities
Work hardening if needed
May take 6 months for full recovery

Follow-Up Schedule

Timepoint	Assessment	Imaging
Week 2	Wound check, suture removal	Optional
Week 4	ROM assessment	Radiographs
Week 6	Healing assessment, K-wire removal	Radiographs
Week 12	Functional outcome	Optional CT if concerns
Month 6	Final outcome	As needed
Year 1	Long-term surveillance	If symptomatic

Rehabilitation should be tailored to individual patient needs and fracture complexity.

Outcomes and Prognosis

Functional Outcomes

Range of Motion Recovery

Wrist flexion: 80-90% of contralateral by 6 months
Wrist extension: 85-95% of contralateral
Forearm rotation: Usually full recovery
Grip strength: 80% of contralateral by 12 months

Patient-Reported Outcomes

DASH scores typically return to near-normal by 12 months
Patient satisfaction correlates with articular reduction quality
Return to previous activity level in 80-90% of well-treated cases

Prognostic Factors

Favorable Factors

Step-off under 1mm achieved at surgery
Younger patient
Isolated injury
Compliant with rehabilitation
Good bone quality

Unfavorable Factors

Residual step-off greater than 2mm
Significant comminution
Associated ligamentous injury
Osteoporotic bone
High-energy mechanism with soft tissue injury

Arthritis Risk

Development of Post-Traumatic Arthritis

The risk is directly related to residual articular incongruity:

Step-Off	Arthritis Risk	Timeline
Under 1mm	10-15%	10+ years
1-2mm	30-40%	5-10 years
Over 2mm	70-90%	2-5 years

Salvage Options for Arthritis

Wrist arthroscopy: Debridement for early arthritis
Partial wrist fusion: Four-corner fusion preserving some motion
Total wrist fusion: Reliable pain relief, loss of motion
Proximal row carpectomy: Motion-preserving salvage
Total wrist arthroplasty: Selected patients

Return to Activity

Work

Sedentary work: 2-4 weeks
Light manual work: 6-8 weeks
Heavy manual work: 12-16 weeks

Sports

Non-contact sports: 8-12 weeks
Contact sports: 4-6 months
High-impact activities: 6+ months

The key predictor of outcome is the quality of articular reduction achieved.

Evidence Base

Level III

📚 Knirk and Jupiter. Intra-articular Fractures of the Distal End of the Radius

Key Findings:

Step-off over 2mm strongly associated with radiographic arthritis
91% arthritis rate with step-off over 2mm
11% arthritis with step-off under 1mm
Articular congruity is primary determinant of outcome

Clinical Implication: This landmark study established the 2mm threshold for acceptable articular reduction that guides modern treatment.

Source: J Bone Joint Surg Am 1986

Level IV

📚 Medoff RJ. Essential Radiographic Evaluation for Distal Radius Fractures

Key Findings:

CT more accurate than radiographs for articular assessment
Plain films underestimate step-off by average 2-3mm
Sagittal CT cuts essential for die-punch evaluation
3D reconstructions aid surgical planning

Clinical Implication: CT scanning is mandatory for accurate assessment of die-punch fractures and surgical planning.

Source: Hand Clin 2005

Level IV

📚 Rikli DA et al. Fragment-Specific Fixation of Distal Radius Fractures

Key Findings:

Fragment-specific approach addresses each component individually
Low-profile implants reduce hardware complications
Subchondral support critical for articular fragments
Good results in complex articular fracture patterns

Clinical Implication: Fragment-specific fixation allows tailored treatment of die-punch and associated fracture components.

Source: J Bone Joint Surg Am 2003

Level III

📚 Harness NG et al. Intraarticular Fractures of the Distal Radius: Correlation of Preoperative CT with Surgical Findings

Key Findings:

CT demonstrated 44% more fragment details than radiographs
Depression severity consistently underestimated on X-ray
CT changed surgical approach in 30% of cases
Improved surgical planning and outcomes

Clinical Implication: Preoperative CT is essential and changes management decisions in a significant proportion of cases.

Source: J Hand Surg Am 2003

Level IV

📚 Fernandez DL. Bone Grafting for Articular Defects in Distal Radius Fractures

Key Findings:

Bone grafting supports elevated articular fragments
Reduces risk of secondary collapse
Autograft preferred for larger defects
Synthetic substitutes acceptable for smaller voids

Clinical Implication: Bone grafting should be considered after elevation of die-punch fragments to prevent secondary subsidence.

Source: Hand Clin 2001

The evidence supports anatomic reduction with stable fixation and bone grafting as needed.

Viva Scenarios

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Die-Punch Fracture Evaluation

EXAMINER

"A 35-year-old man presents after falling 3 meters from a ladder onto an outstretched hand. Plain radiographs show a distal radius fracture with subtle articular involvement. How do you evaluate this injury?"

EXCEPTIONAL ANSWER

This is a high-energy distal radius fracture in a young patient that requires thorough evaluation. My approach would be: **Initial Assessment:** I would first ensure this is an isolated injury by examining the entire upper limb including the elbow, forearm, and carpus. I would document neurovascular status, specifically median nerve function given the risk of acute carpal tunnel syndrome with swelling. **Plain Radiograph Analysis:** I would carefully assess the lateral radiograph for any dorsal cortical disruption or loss of the normal concave lunate facet contour. On the PA view, I would look for articular surface irregularity and the double cortical sign suggesting a depressed fragment. **CT Scanning:** Given the high-energy mechanism and any suspicion of articular involvement, I would obtain a CT scan with sagittal and coronal reconstructions. This is mandatory because plain radiographs underestimate articular depression by 2-3mm on average. I would specifically measure any step-off in the lunate facet region. **Associated Injury Assessment:** High-energy wrist injuries commonly have associated scapholunate ligament injuries, so I would assess this clinically with the Watson test and radiographically by measuring the scapholunate interval. **Decision-Making:** If CT confirms articular step-off greater than 2mm, I would recommend surgical reduction and fixation. If under 2mm, non-operative management may be appropriate with close follow-up to detect secondary displacement.

KEY POINTS TO SCORE

CT is mandatory for any suspected articular fracture

High-energy mechanism increases risk of associated injuries

2mm step-off is the surgical threshold

Assess for scapholunate ligament injury

COMMON TRAPS

✗Missing die-punch by relying only on plain radiographs

✗Not assessing for associated carpal ligament injuries

✗Underestimating the severity based on minimal deformity

LIKELY FOLLOW-UPS

"What specific CT views would you request?"

"How do you assess scapholunate ligament integrity?"

"What is the Knirk and Jupiter threshold for articular step-off?"

VIVA SCENARIOChallenging

Die-Punch Surgical Planning

EXAMINER

"CT confirms a Type II Sander-Medoff die-punch fracture with 4mm articular depression and a sagittal split component. How do you plan your surgical approach?"

EXCEPTIONAL ANSWER

This is a Type II die-punch fracture with significant displacement requiring operative fixation. **Surgical Goals:** My goals are to achieve anatomic articular reduction with step-off under 1mm, provide stable subchondral support to the elevated fragment, and address the split component to restore overall stability. **Approach Selection:** For a Type II die-punch with depression and split, I would favor a dorsal approach. This provides direct visualization of the lunate facet, which is essential for accurate reduction of the depressed fragment. The dorsal approach allows me to elevate the fragment under direct vision rather than relying on fluoroscopy alone. **Surgical Technique:** Through a longitudinal dorsal incision centered on Lister tubercle, I would enter between the third and fourth compartments, protecting the EPL. After capsulotomy, I would directly visualize the articular surface. For reduction, I would use a small elevator to lever the depressed fragment back to the articular level. The split component would be reduced with pointed reduction clamps. **Fixation Strategy:** I would use fragment-specific fixation. The split component requires a screw or K-wires for compression. The elevated die-punch fragment needs subchondral support, which I would achieve with a low-profile dorsal plate with distal locking screws positioned just beneath the subchondral bone. **Bone Grafting:** After elevation, I expect a metaphyseal void. I would fill this with cancellous bone graft, either autograft from the distal radius metaphysis or a synthetic substitute. This prevents secondary collapse of the elevated fragment. **Intraoperative Assessment:** I would confirm reduction with direct visualization and fluoroscopy in multiple planes, ensuring no screw penetration into the joint.

KEY POINTS TO SCORE

Dorsal approach provides direct visualization of die-punch

Address both depression and split components

Bone graft the metaphyseal void

Fragment-specific fixation with subchondral support

COMMON TRAPS

✗Using only volar approach when dorsal visualization is needed

✗Forgetting to bone graft the metaphyseal defect

✗Inadequate fixation of split component

LIKELY FOLLOW-UPS

"What bone graft options would you consider?"

"How do you confirm adequate reduction intraoperatively?"

"How would you modify your approach if there is an associated volar fragment?"

VIVA SCENARIOChallenging

Die-Punch Complication Management

EXAMINER

"Six months after ORIF of a die-punch fracture, your patient complains of progressive wrist pain and stiffness. Radiographs show early degenerative changes at the radiocarpal joint. How do you manage this?"

EXCEPTIONAL ANSWER

This patient has developed post-traumatic radiocarpal arthritis, which is the most significant long-term complication of die-punch fractures. **Initial Assessment:** I would take a detailed history regarding pain severity, functional limitations, and how this affects their daily activities and work. I would examine for range of motion, grip strength, and localize tenderness to confirm radiocarpal involvement. **Imaging Evaluation:** I would obtain updated radiographs and consider CT to assess the degree of articular incongruity and joint space narrowing. I would also review the original CT and postoperative imaging to determine if this is related to residual step-off or represents progression despite acceptable reduction. **Conservative Management:** For early arthritis, I would first trial non-operative measures including activity modification, anti-inflammatory medications, a wrist splint for symptom relief, and referral to hand therapy. Corticosteroid injection can provide temporary relief and may be diagnostic for radiocarpal versus midcarpal symptoms. **Surgical Options:** If conservative measures fail, surgical options depend on the severity and patient factors. For mild to moderate arthritis with preserved midcarpal joint, I would consider wrist arthroscopy for debridement and assessment, or a motion-preserving procedure such as proximal row carpectomy if the capitate head cartilage is intact. For severe arthritis, options include partial wrist fusion such as radioscapholunate fusion, or total wrist fusion for reliable pain relief at the cost of motion. **Patient Counseling:** I would explain that post-traumatic arthritis can be progressive and that the goal is to manage symptoms while maintaining function as long as possible. If surgery is needed, the choice depends on their functional demands, age, and severity of disease. This case highlights why achieving anatomic reduction under 2mm step-off is so critical in die-punch fractures.

KEY POINTS TO SCORE

Post-traumatic arthritis is the main long-term complication

Trial conservative management first

Surgical options range from debridement to fusion

Prevention through anatomic reduction is key

COMMON TRAPS

✗Rushing to surgical salvage without adequate conservative trial

✗Not addressing patient expectations about outcome limitations

✗Overlooking the original reduction quality as contributing factor

LIKELY FOLLOW-UPS

"What are the differences between proximal row carpectomy and total wrist fusion?"

"What patient factors influence your choice of salvage procedure?"

"How do you counsel about expected outcomes after salvage surgery?"

MCQ Practice Points

Diagnostic Imaging

Q: What is the most important imaging modality for assessing die-punch fractures? A: CT scanning with sagittal reconstructions is mandatory. Plain radiographs underestimate articular depression by 2-3mm on average and frequently miss die-punch components entirely.

Articular Step-Off Threshold

Q: What articular step-off threshold is associated with post-traumatic arthritis development? A: Greater than 2mm step-off is the critical threshold. Knirk and Jupiter demonstrated 91% arthritis rate with step-off over 2mm versus 11% with step-off under 1mm.

Anatomical Location

Q: Which articular surface is affected in a die-punch fracture? A: The lunate facet of the distal radius. The lunate acts as the punch driving into the softer cancellous bone of the radial die during axial loading.

Surgical Approach Selection

Q: What surgical approach best allows direct visualization of a dorsal die-punch fragment? A: The dorsal approach through the third and fourth extensor compartments. This provides direct visualization of the lunate facet, whereas volar approaches rely on fluoroscopic guidance for dorsal fragments.

Bone Grafting Indication

Q: Why is bone grafting often required after die-punch fragment elevation? A: Elevation of the depressed fragment creates a metaphyseal void. Without bone graft or substitute to fill this void, the elevated fragment lacks subchondral support and may undergo secondary collapse.

Load Transmission

Q: What percentage of wrist axial load is transmitted through the lunate facet? A: Approximately 60% of axial load crosses the wrist through the lunate facet. This high load-bearing function explains why articular incongruity leads to rapid degenerative changes.

Understanding these key concepts will help with exam success.

Australian Context

Die-punch fractures represent a significant subset of distal radius fractures managed across Australian trauma centers. High-energy mechanisms such as falls from height in construction and agricultural settings, as well as motorcycle and cycling accidents, are common etiologies in the Australian context.

The Australian orthopaedic community follows international consensus regarding the 2mm step-off threshold for surgical intervention. CT scanning is standard practice for preoperative planning, with most major centers having ready access to quality imaging.

Fragment-specific fixation techniques and volar locking plates are widely available throughout Australia. Bone graft substitutes are commonly used, with iliac crest autograft reserved for larger defects or revision situations.

Rehabilitation follows international guidelines, with hand therapy services available in most metropolitan areas. Regional patients may require telehealth rehabilitation support or temporary relocation for intensive therapy.

The Australian healthcare system provides comprehensive coverage for die-punch fracture treatment through both public and private pathways, ensuring access to appropriate surgical care regardless of geographic location.