FCPS IMM Master Official Exam Master Bank

Distal Humerus Fractures

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FCPS IMM Master Revision File

Distal Humerus Fractures: High-Yield Text + 22 MCQs

Aligned with standard orthopaedic trauma board curricula including AO/OTA, Milch, and Jupiter classifications, surgical exposures, and complications.

1. Epidemiology & Prognosis

Incidence, mechanics, associated trauma, and outcomes

Incidence & Demographics

• Incidence: Accounts for 0.5% to 7% of all body fractures and 30% of all elbow fractures.
• Bimodal Distribution: Young males (high-energy trauma) vs older females (low-energy osteoporotic falls).
• Most Common Pattern: Distal intercondylar fractures.

Pathoanatomy & Mechanism (High Yield)

• Elbow flexed < 90°: Axial load leads to a transcolumnar fracture; direct posterior blow leads to an olecranon fracture.
• Elbow flexed > 90°: Forces drive into trochlea, where the rigid olecranon acts as a wedge, splitting the condyles into an intercondylar fracture.

Associated Injuries

Elbow dislocation, terrible triad injury, floating elbow, and Volkmann contracture (resulting from a missed forearm compartment syndrome).

Prognosis & ROM Target

Majority regain 75% of motion and strength. Goal is to restore elbow ROM to 30–130° of flexion. Unsatisfactory outcomes in up to 25% (due to low fracture lines, metaphyseal fragmentation, articular comminution, or poor bone quality).

2. Core Anatomy

Osteology, muscle origins, ligaments, and nerves at risk

Osteology

The elbow is a hinged joint. The trochlea articulates with the sigmoid notch (flexion/extension). The capitellum articulates with the proximal radius (forearm rotation).

Muscles

• Common Flexors (Medial Epicondyle): Pronator teres, FCU, FCR, Palmaris longus, FDS.
• Common Extensors (Lateral Epicondyle): Anconeus, ECRL, ECRB, EDC, EDM, ECU.

Ligaments (Crucial for Stability)

• MCL: Anterior bundle originates from distal medial epicondyle and inserts on sublime tubercle. Primary restraint to valgus stress from 30–120°; tight in pronation.
• LCL: Originates from distal lateral epicondyle and inserts on crista supinatorius. Stabilizer against posterolateral rotatory instability (PLRI); tight in supination.

Nerves (Crucial for Approaches & Injuries)

Ulnar Nerve: Resides in the cubital tunnel in a subcutaneous position below the medial condyle. Frequently at risk during medial surgical approaches.

Radial Nerve: Resides in the spiral groove 15 cm proximal to the distal humeral articular surface. Runs between brachioradialis and brachialis, dividing into PIN and superficial radial nerve at radial head level.

3. Classification Systems

AO/OTA, Milch, and Jupiter classifications

AO/OTA Classification

• Type A: Extraarticular (supracondylar). 80% are extension type.
• Type B: Intraarticular – Single column (Partial articular: isolated condylar, coronal shear, epicondyle with extension).
• Type C: Intraarticular – Both columns fractured, no portion of joint contiguous with shaft (Complete articular).

Milch Classification

For Single Column Condyle Fractures:

• Type I: Lateral trochlear ridge is intact (stable).
• Type II: Fracture goes through lateral trochlear ridge (making elbow inherently unstable).

Jupiter Classification

For Bicolumnar Fractures (5 Major Fragments):

1. Capitellum/lateral trochlea
2. Lateral epicondyle
3. Posterolateral epicondyle
4. Posterior trochlea
5. Medial trochlea/epicondyle

4. Presentation & Diagnostic Workup

Clinical evaluation, neurovascular risks, and imaging choices

Symptoms & Physical Exam

• Symptoms: Elbow pain and swelling. Gross instability often present.
• Precaution: Avoid ROM on initial exam due to risk of neurovascular damage.
• Neurovascular Exam: Must check radial, ulnar, median nerves, and distal pulses.
• Vascular Emergency: Brachial artery may be injured. If pulse is decreased, obtain noninvasive vascular studies and consult vascular surgery.
• Monitor carefully for forearm compartment syndrome.

Imaging Protocols

• Radiographs: AP & Lateral. Oblique and traction radiographs used for surgical planning (evaluates continuity of trochlear fragment with medial epicondyle to decide hardware choice).
• CT Scan: Obtained for surgical planning; especially helpful when shear fractures of capitellum and trochlea are suspected.
• MRI: Usually not indicated in acute setting.

5. Treatment Algorithms

Nonoperative positioning, CRPP, ORIF, and Total Elbow Arthroplasty

Nonoperative (Cast)

Indication: Nondisplaced Milch Type I.

Supination: For lateral condyle (relaxes extensor origin).

Pronation: For medial condyle (relaxes flexor origin).

CRPP

Closed Reduction Percutaneous Pinning.

Indication: Displaced Milch Type I fractures.

ORIF

Indications: Supracondylar, Intercondylar/Bicollumnar, and Milch Type II fractures (absolute indication).

TEA (Arthroplasty)

Indications: Elderly patients with comminuted articular fractures in osteoporotic bone or RA.

Restriction: Cannot lift > 5 lbs post-op.

6. Surgical Techniques & Approaches

Posterior exposures, hardware rules, ulnar nerve, and post-op protocol

Superficial Approaches (Posterior)

• Triceps-splitting: Midline split down to olecranon.
• Triceps-sparing (Paratricipital/Alonso-Llames): Extra-articular or simple split. Elevate triceps via medial/lateral windows. Convertible to olecranon osteotomy.
• Olecranon Osteotomy: Complex intra-articular or coronal split. Chevron (apex distal) osteotomy. Absolute Contraindication: TEA is planned/required. Complication: AIN injury (check thumb IP flexion / FPL).
• Bryan-Morrey (Triceps-reflecting): Reflects triceps tendon/fascia off olecranon medial to lateral. Repaired via drill holes; requires 4–6 weeks protection.
• Lateral Muscle Interval: Elevates ECRB/ECRL off supracondylar ridge.

Fixation Principles & Post-Op Protocol

• Provisional reduction with K-wires.
• Articular Fragments: Countersunk or headless screws.
• Trochlea: Positional screws to avoid narrowing trochlea with compression.
• Columns: Dual plates in orthogonal or parallel planes.
• Ulnar Nerve: Transposition optional; literature does NOT support decreased symptoms with transposition.
• Post-Op Protocol: Splint at 70° flexion; remove at 48h for active ROM. With osteotomy: active/assisted flex/ext 6 wks (no active extension against gravity). Without osteotomy: active motion against gravity immediately. Strengthening at 6 wks; full strengthening at 3 months.

7. Complications

Stiffness, HO rules, malunions, nerve injuries, and DJD

Elbow Stiffness

Most common complication overall. Early active motion at 48 hours is critical.

Heterotopic Ossification (HO)

Seen in 8%. Routine prophylaxis is NOT warranted because indomethacin increases the rate of nonunion.

Malunion Deformities

Cubitus valgus: Lateral column fractures.
Cubitus varus: Medial column fractures ('gunstock').

FCPS IMM Master MCQ Bank (22 Questions)

All questions with detailed explanations for clinical reasoning & exam traps

High-Yield Recall

Rapid Revision & Board Exam Pearls

Instant key facts and high-yield traps frequently tested in FCPS IMM, MRCS, and Orthopaedic Boards.

Anatomical Landmarks & Distances

• • Radial Nerve Spiral Groove: Lies 15 cm proximal to distal humeral articular surface.
• • MCL Insertion: Anterior bundle inserts on the sublime tubercle of coronoid.
• • LCL Insertion: Inserts on the crista supinatorius of the ulna.
• • Functional ROM Goal: 30° extension to 130° flexion.

Must-Know Surgical Traps

• • Olecranon Osteotomy Contraindication: NEVER do an olecranon osteotomy if a Total Elbow Arthroplasty (TEA) is planned.
• • AIN Injury Risk: Proximal drill bit placement during olecranon fixation can injure the Anterior Interosseous Nerve (loss of FPL / thumb IP flexion).
• • Heterotopic Ossification: Routine indomethacin/prophylaxis is NOT recommended due to increased rate of nonunion.
• • Trochlear Screw Compression: Avoid lag compression across trochlear fragments to prevent narrowing of the trochlear notch. Use positional screws.

Non-Op Casting Rules

• • Nondisplaced Lateral Condyle Fracture: Cast in supination (relaxes extensor origin).
• • Nondisplaced Medial Condyle Fracture: Cast in pronation (relaxes flexor origin).
• • Milch Type II Fractures: Inherently UNSTABLE; always require ORIF.

Arthroplasty vs ORIF Rules

• • TEA Indications: Elderly, osteoporotic, un-reconstructible intra-articular comminution, rheumatoid arthritis.
• • Post-TEA Restriction: Strict permanent 5 lb (2.3 kg) weight lifting restriction.
• • ORIF Fixation Goal: Anatomic reduction of articular surface, rigid dual column plating, early active ROM by 48 hours.

Classification Systems Comparison

Quick reference matrix comparing AO/OTA, Milch, and Jupiter classification criteria.

System	Category / Type	Anatomical Fracture Description	Clinical Significance
AO / OTA	Type A	Extra-articular (Supracondylar)	80% extension type; joint surface intact.
	Type B	Partial articular (Single column / shear / epicondyle)	Part of articular surface remains continuous with shaft.
	Type C	Complete articular (Bicolumnar)	No articular segment attached to humeral shaft. Requires dual plating.
Milch	Type I	Lateral trochlear ridge remains intact	Inherent joint stability maintained; candidates for conservative/CRPP.
	Type II	Fracture line extends through lateral trochlear ridge	Inherently UNSTABLE; high risk of elbow translocation; absolute ORIF indication.
Jupiter	Bicolumnar Subtypes	High T, Low T, Y-type, H-type, Medial/Lateral sagittal split	Guides plate position (parallel vs orthogonal) and surgical strategy.

Surgical Approaches Matrix

Comparative breakdown of posterior surgical exposures of the distal humerus.

Approach	Technique / Mechanism	Articular Exposure	Key Advantages	Key Risks / Traps
Triceps-Sparing (Paratricipital / Alonso-Llames)	Elevates triceps off medial and lateral intermuscular septa	Limited articular exposure	Extensor mechanism left intact; allows immediate active extension	Inadequate for complex intra-articular fractures
Olecranon Osteotomy	Chevron osteotomy of olecranon 2 cm from tip; reflected proximally with triceps	Gold standard (100% visualization of distal articular surface)	Unmatched articular visualization for complex C3 fractures	Osteotomy nonunion, hardware prominent, AIN nerve injury, NEVER use if TEA planned
Bryan-Morrey (Triceps-Reflecting)	Reflects triceps tendon and forearm fascia intact from medial to lateral off olecranon	Good articular exposure	Avoids olecranon osteotomy; ideal if converting to TEA	Triceps insertion avulsion/failure; requires protected active extension for 4-6 weeks
Triceps-Splitting (Campbell)	Longitudinal split in triceps muscle and tendon down to bone	Moderate exposure	Direct central trajectory	Triceps muscle scarring, weakness, and direct muscle tissue trauma