High Yield Overview
Ref: Trochlea (Laugier) Fractures
Isolated shear fractures of the humeral trochlea
IncidenceExtremely Rare
PatternCoronal Shear
MechanismAxial Load + Varus
NicknameLaugier Fracture
AO/OTA Classification (13-B3)
Type I
PatternSimple articular fracture (shear).
TreatmentORIF (Volar/Medial)
Type II
PatternComminuted articular fracture.
TreatmentORIF vs TEA (Elderly)
Type III
PatternAssociated with Capitellum fx (Dubberley).
TreatmentComplex ORIF
Critical Must-Knows
- Rare Entity: Isolated trochlea fractures are rare. Usually part of a transcondylar or capitellum fracture.
- Shear Injury: Like the capitellum, these are coronal shear fractures with no soft tissue attachments (free floating).
- Double Arc Sign: On lateral X-ray, seen as a second arc behind the capitellum (often missed).
- Surgical Approach: Requires a medial approach (Over-the-top or Osteotomy) for visualization.
Examiner's Pearls
- "Missed Diagnosis: Often misdiagnosed as a medial epicondyle fracture or 'sprain'.
- "Ulnar Nerve: High risk of injury due to proximity.
- "Instability: Loss of the trochlea causes ulno-humeral instability.
Clinical Imaging
Imaging Gallery
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Critical Diagnostics
The Hidden Fracture
Isolated trochlea fractures are invisible on AP X-ray (overlapped by ulna). The lateral view shows the "Double Arc" sign but is subtle.
The Free Fragment
The fragment has NO soft tissue attachments. It is purely articular. Blood supply is entirely retroactive from subchondral bone (which is fractured). High AVN risk.
Associated Injuries
Look for associated Elbow Dislocation or Capitellum fracture (creates a Type IV capitellum fracture).
CT is Mandatory
You cannot plan this surgery without a CT scan. It defines Articular comminution.
Quick Decision Guide - Management
| Condition | Treatment | Approach | Key Factor |
|---|---|---|---|
| Non-displaced | Cast Immobilization | N/A | Very rare to be stable. |
| Displaced (Simple) | **ORIF** | Medial Column/Osteotomy | Headless compression screws (A-P or P-A). |
| Comminuted (Elderly) | **TEA (Total Elbow)** | Posterior | Bone stock usually too poor for screws. |
| Small Fragment | **Excision** | Medial | Only if fragment is less than 20% of surface. |
Mnemonic
Double ArcRadiographic Signs
Double
Double Arc Sign
On lateral view, the trochlea arc is seen separate from capitellum arc.
Drop
Drop Sign
Ulnohumeral distance increases if trochlea is displaced.
Memory Hook:Seeing double? Check the trochlea.
Mnemonic
ARCSurgical Goals
A
Anatomic Reduction
Articular step-off leads to arthritis.
R
Rigid Fixation
Allows early motion (crucial for elbow).
C
Compression
Headless screws to bury beneath cartilage.
Memory Hook:Restore the ARC of motion.
Mnemonic
M-U-TThe Medial Column
M
Medial Epicondyle
Origin of flexors, landmark for approach.
U
Ulnar Nerve
The structure at risk.
T
Trochlea
Supported by the medial column.
Memory Hook:Don't be a MUT, check the nerve.
Overview and Epidemiology
Definition: A Trochlea fracture (specifically Laugier's fracture) is an isolated coronal shear fracture of the joint surface of the trochlea. It does not involve the columns (unless associated with complex fractures).
Epidemiology:
- Extremely Rare. Represents less than 1% of distal humerus fractures.
- Demographics: Young males (high energy) or Osteoporotic females.
- Pathoanatomy: The trochlea is the "spool" of the elbow. It provides intrinsic stability (constrained joint). Loss of the trochlea allows the ulna to slide medially/laterally or dislocate.
Anatomy
Bony Anatomy:
- Trochlea: A spool-shaped structure covered in cartilage through an arc of 300 degrees.
- Sulcus: The central groove articulates with the trochlear notch of the ulna.
- Medial Ridge: More prominent than lateral ridge. Provides valgus stability.
- Center of Rotation: The axis of rotation passes through the center of the trochlea (and capitellum).
- Articular Contact: The ulna articulates with the trochlea in both flexion and extension. Loss of the trochlea results in rapid ulnar migration and instability.
Vascularity:
- Watershed: The trochlea is supplied by small vessels entering via the medial capsule and non-articular areas.
- Fracture: The fracture is intra-articular and separates the bone from its blood supply (like an iceberg). High risk of AVN/Non-union.
- Posterior Comminution: Indicates disruption of the posterior vascular supply.
Nerves:
- Ulnar Nerve: Runs immediately posterior to the medial epicondyle. Must be identified and protected (or transposed) in any medial approach.
- Medial Antebrachial Cutaneous Nerve (MABCN): At risk during the superficial dissection. Injury causes painful neuroma.
Muscle Attachments:
- Flexor-Pronator Mass: Originates from the medial epicondyle. Must be elevated or split to access the anterior aspect of the trochlea.
- Triceps: Inserts on the olecranon, but its medial border covers the posterior aspect of the medial column.
Classification Systems
- 13-A: Extra-articular.
- 13-B: Partial Articular.
- B1: Lateral Sagittal (Capitellum).
- B2: Medial Sagittal (Trochlea - Rare).
- B3: Frontal/Coronal Plane (Shear).
- B3.1: Capitellum alone (Hahn-Steinthal).
- B3.2: Trochlea alone (Laugier).
- B3.3: Capitellum + Trochlea (McKee).
Clinical Assessment
History:
- Fall on outstretched hand (FOOSH) with elbow slightly flexed and in varus?
- Direct blow?
- Pain, swelling, inability to move elbow.
Physical Exam:
- Swelling: Medial sided bruising (Ecchymosis).
- Palpation: Tenderness over medial column.
- ROM: Block to flexion/extension implies a mechanical block (loose fragment).
- Neurology: CHECK ULNAR NERVE. Tardy ulnar nerve palsy is a late complication, but acute neuropraxia is common from the blow.
Investigations
Plain X-rays:
- AP: Often looks normal or shows a faint "flake" medially.
- Lateral: The Diagnostic View. Look for:
- Double Arc Sign (Two semi-circles).
- Superior migration of the fragment.
- "Chewed up" appearance of the joint line.
CT Scan:
- Absolute Requirement.
- 2D Views:
- Coronal: Shows the shearing nature and size of the fragment.
- Sagittal: Shows posterior comminution (Dubberley B).
- 3D Reconstruction:
- Essential for preoperative planning of screw trajectory.
- Determine if you can screw Front-to-Back (easier) or need Back-to-Front (harder).
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Management Algorithm
📊 Management Algorithm
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Decision Making:
-
Fragment Size:
- Small (less than 20%): Excision.
- Large (greater than 20%): Fixation.
-
Displacement:
- Non-displaced: Cast (verify with CT).
- Displaced: ORIF.
-
Bone Quality:
- Good: Headless Screws.
- Poor (Elderly): TEA (Total Elbow Arthroplasty).
Surgical Techniques
1. Medial Approach (Hotchkiss/Over-the-top):
- Incision over medial supracondylar ridge.
- Identify Ulnar Nerve. Release cubital tunnel.
- Elevate flexor-pronator mass anteriorly (or split it).
- Limitation: Hard to see the lateral extent of the trochlea.
2. Chevron Osteotomy (Medial Epicondyle):
- Pre-drill the medial epicondyle.
- Perform osteotomy.
- Reflect flexor mass distally.
- Benefit: Excellent view of the trochlea.
- Repair: Screw fixation of the epicondyle at the end.
3. Olecranon Osteotomy:
- Typically used for intercondylar fractures, but can be used here for posterior access.
Complications
- Nonunion / AVN:
- The fragment is devoid of soft tissue attachments.
- AVN creates a sequestrum which causes pain and locking.
- Treatment: Excision and TEA.
- Arthritis:
- Rapid onset if step-off remains.
- "The elbow tolerates congruity poorly."
- Ulnar Neuropathy:
- Due to surgical handling or scar tissue.
- Routine anterior transposition is debated but often done in complex cases.
- Heterotopic Ossification (HO):
- Medial side is lower risk than lateral/posterior, but still possible.
Postoperative Care
- Phase 1 (0-2 Weeks):
- Splint at 90 degrees.
- Elevation.
- Phase 2 (2-6 Weeks):
- Active Motion: Start AROM immediately if fixation is rigid.
- Gravity assisted flexion/extension.
- Avoid varus stress.
- Phase 3 (6+ Weeks):
- Strengthening.
- Wean splint.
Outcomes/Prognosis
- Rare Injury: Data is scarce (Case series only).
- Results: Generally good if anatomic reduction achieved (greater than 80% satisfaction).
- Failures: High rate of conversion to TEA in elderly patients or failed fixation.
- ROM: Loss of terminal extension (10-15 degrees) is common and acceptable.
- Arthritis: Post-traumatic arthritis is common (50% at 10 years).
- Heterotopic Ossification: Occurs in 10-20% of cases due to extensive dissection. Prophylaxis (Indomethacin) is recommended.
Evidence
The Laugier Fracture
Laugier • Historically described (1853)
Key Findings:
- First description of the isolated trochlea fracture.
- Noted the instability of the ulna that results.
Clinical Implication: Historical context.
Dubberley Classification
Dubberley et al • J Bone Joint Surg Br (2006)
Key Findings:
- Outcome depends on Posterior Comminution (Type B).
- Type A (No comminution) did well with ORIF.
- Type B (Comminuted) had high failure rate.
Clinical Implication: Posterior comminution predicts failure.
Surgical Approach
McKee et al • J Shoulder Elbow Surg (2010)
Key Findings:
- Extensile approaches required for complex shear fractures.
- Fixation with headless screws buried in cartilage is the standard.
Clinical Implication: Exposure is key.
Excision vs Fixation
Grant et al • J Trauma (2005)
Key Findings:
- Small fragments can be excised without gross instability.
- Large fragments must be fixed.
Clinical Implication: Size matters (20% rule).
TEA for Salvage
Morrey et al • JBJS (2000)
Key Findings:
- Total Elbow Arthroplasty is a reliable salvage for failed distal humerus fixation.
- 10-year survival greater than 90% in low demand patients.
Clinical Implication: Don't be afraid to bail out to TEA in elderly.
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
VIVA SCENARIOStandard
EXAMINER
"A 60-year-old female presents with a 'swollen elbow' after a fall. X-ray AP looks normal. She cannot flex past 90 degrees."
EXCEPTIONAL ANSWER
Diagnosis:
- Differential: Occult fracture (Radial head, Coronoid, or Trochlea). Ligamentous injury.
- Red Flag: Mechanical block suggests a loose body.
- Next Step: True Lateral X-ray (Look for Double Arc Sign) and CT Scan.
- Result: Likely an isolated Trochlear shear fracture (Laugier).
KEY POINTS TO SCORE
Occult fracture differential (radial head, coronoid, trochlea)
Mechanical block suggests loose body - red flag
True lateral X-ray and CT scan required
Double Arc Sign pathognomonic for coronal shear
COMMON TRAPS
✗Missing subtle fracture on AP view alone
✗Not obtaining true lateral radiograph
✗Failing to recognize mechanical block significance
LIKELY FOLLOW-UPS
"What is the Double Arc Sign?"
"How would you classify this fracture?"
"What surgical approach would you use?"
VIVA SCENARIOChallenging
EXAMINER
"Intra-op, you have fixed the trochlea fracture but the screw heads are prominent in the articular surface."
EXCEPTIONAL ANSWER
Options:
- Countersink: Ensure you have countersunk the hole before inserting the screw.
- Change Screw: Use a smaller headless screw (Acutrak Mini vs Micro).
- Direction: Insert from non-articular surface (posterior to anterior) if possible, but this is technically harder for coronal shear.
- Implication: Prominent hardware = Rapid chondrolysis and arthritis. Must be flush or buried.
KEY POINTS TO SCORE
Countersinking essential for articular screws
Headless compression screws preferred
Posterior-to-anterior direction if possible
Prominent hardware causes rapid chondrolysis
COMMON TRAPS
✗Using screws that are too large
✗Inadequate countersinking
✗Leaving proud hardware in articular surface
LIKELY FOLLOW-UPS
"What size screws do you typically use?"
"How do you assess adequate countersinking?"
"What is your postoperative rehabilitation protocol?"
MCQ Practice Points
Radiology
Q: What is the 'Double Arc Sign' on a lateral elbow radiograph pathognomonic for? A: Capitellum and Trochlea shear fractures (McKee Type IV / Dubberley).
Anatomy
Q: Which column of the distal humerus supports the Trochlea? A: The Medial Column.
Complications
Q: Which nerve is most at risk during fixation of a Laugier fracture? A: Ulnar Nerve (Posterior to medial epicondyle).
Treatment
Q: What is the preferred fixation method for a Type I coronal shear fracture? A: Headless Compression Screws (A-P direction).
Prognosis
Q: What factor most strongly predicts failure of fixation? A: Posterior Comminution (Dubberley B).
Australian Context
- Referral: Rare injury. Should be managed by an Upper Limb specialist.
- Centres: Major Trauma Centres (MTC) or Upper Limb Units.
- Implants: Acutrak/Herbert screws standard. TEA availability is required for backup.
Trochlea Essentials
High-Yield Exam Summary
Key Concepts
- •Coronal Shear Injury
- •Double Arc Sign
- •Medial Approach
- •Headless Screws
Classification (Dubberley)
- •Type 1: Capitellum
- •Type 2: Cap + Trochlea (Fused)
- •Type 3: Cap + Trochlea (Mallet)
- •Modifier B: Posterior Comminution
Imaging
- •Lateral View is key
- •CT Mandatory
- •Rule out terrible triad
- •Rule out capitellum fx
Complications
- •Ulnar Neuropathy
- •AVN (Thal)
- •Stiffness (Loss of extension)
- •Arthritis