Capitellum and Coronal Shear Fracture ORIF

Surgical Indications

Absolute Indications

• Displaced coronal shear fracture (articular step greater than 2 mm, or any rotational malalignment that blocks motion) — the articular step-off at the radiocapitellar joint accelerates post-traumatic arthritis
• Locking or blocking of flexion / extension by a rotated capitellar fragment — a common presentation; the rotated fragment impinges in the coronoid / radial fossa
• Hahn-Steinthal whole-capitellum fracture in any age group with a reconstructable fragment — fixation is preferred to excision because excision produces radial-migration and proximal radial instability
• Dubberley type A1, A2, B1, B2 in the active patient — lateral approach ORIF is the standard of care
• Open fracture — urgent irrigation, debridement, and ORIF; antibiotic cover; assess for compartment syndrome

Relative Indications

• Small, non-reconstructable cartilage flake (Kocher-Lorenz) in a low-demand elderly patient — fragment excision with symptom-driven treatment is a reasonable alternative
• Comminuted capitellum with extensive posterior wall involvement (Dubberley type A3 or B3) — consider staged ORIF versus primary fragment excision and early total elbow arthroplasty in the very low-demand elderly patient
• Associated elbow dislocation that has been reduced — the ligamentous injury must be addressed; fixation of the capitellar fragment alone is insufficient

Contraindications

Absolute:

• Active elbow sepsis — infection must be cleared before ORIF (or convert to excision and antibiotic spacer)
• Patient medically unfit for surgery

Relative:

• Very low-demand elderly patient with a comminuted unreconstructable capitellar and trochlear injury — consider acute total elbow arthroplasty
• Established post-traumatic arthritis with loss of cartilage on the donor condyle — fixation cannot restore a destroyed joint surface
• Severe osteoporosis that prevents stable screw purchase — consider suture fixation or fragment excision

Evidence for Operative Treatment

Outcomes of ORIF — Modern Series

• ORIF of displaced coronal shear fractures restores a congruent radiocapitellar joint in the majority of patients, with reported good-to-excellent functional outcomes (Broberg-Morrey scores in the good-to-excellent range) in approximately 70-90 percent of patients in modern series
• Functional arc of motion is restored in the majority of patients, although the mean flexion-extension arc achieved is typically less than the uninjured elbow by 10-30 degrees
• The strongest predictor of outcome is the QUALITY OF THE INITIAL REDUCTION: an articular step greater than 2 mm correlates strongly with the development of post-traumatic arthritis and poor functional outcome
• Avascular necrosis of the capitellar fragment is reported in 0-25 percent of cases across series; clinically significant AVN requiring further surgery is uncommon because the surrounding condylar shell contains the fragment

Evidence for Headless Compression Screw Fixation

• Headless compression screws (Herbert, Acutrak, Mini-Acutrak) have become the implant of choice because the differential thread pitch produces interfragmentary compression AND the screws can be buried beneath the articular cartilage, avoiding intra-articular prominence
• Biomechanical studies show that headless compression screws provide superior initial stability to K-wires and to bioabsorbable pins in coronal shear fragments
• Two to three screws are typical; the trajectory (AP versus PA) is determined by the fragment geometry and the integrity of the posterior condylar cortex
• For very small or osteoporotic fragments, supplementary fixation with mini-fragment plates, suture anchors, or bioabsorbable pins has been described — outcomes are more variable

Comparison: ORIF vs Fragment Excision

• Modern series favour ORIF over excision for all reconstructable fragments because ORIF restores radiocapitellar congruity and prevents proximal radial migration
• Excision is reserved for non-reconstructable fragments (Kocher-Lorenz thin cartilage flake; severely comminuted fragments in low-demand patients)
• Long-term follow-up of ORIF shows progressive post-traumatic arthritis in a subset of patients — this appears to be more closely related to the INITIAL ARTICULAR INJURY (cartilage damage at the time of impact) than to the fixation technique

Key Evidence

Distal Humeral Articular Anatomy

The Capitellum

• The capitellum is the ANTERIOR and INFERIOR articular surface of the lateral column of the distal humerus
• It articulates with the radial head — the radiocapitellar joint transmits axial load from the forearm to the humerus
• It lies entirely ANTERIOR to the humeral shaft axis: a true lateral radiograph shows the capitellum sitting at or just anterior to the line drawn down the anterior cortex of the distal humeral shaft
• The capitellum is the only portion of the distal humerus that articulates with the radius; it does not articulate with the ulna
• Dimensions: roughly 2-3 cm in medio-lateral width, 1.5-2 cm in antero-posterior depth at the largest point

The Trochlea

• The trochlea is the medial counterpart of the capitellum and articulates with the trochlear notch of the ulna
• It has a central groove, with medial and lateral ridges
• The LATERAL ridge of the trochlea articulates with the radial side of the greater sigmoid notch
• Lateral ridge involvement is the basis of the 'double arc sign' on the lateral radiograph (capitellum + lateral trochlear ridge produce two arcs)
• The trochlea is more POSTERIOR than the capitellum — coronal shear fractures that extend into the trochlea typically involve the lateral ridge, which lies at the junction between the two articular surfaces

Blood Supply of the Capitellum

• The capitellum receives its blood supply from the radial collateral artery and the recurrent interosseous artery (a branch of the common interosseous)
• These vessels enter the capitellum POSTEROLATERALLY, through the lateral epicondylar soft-tissue attachments
• The intra-osseous vascular anatomy of the capitellum is tenuous; the anterior cartilaginous portion of the capitellum has limited direct blood supply
• Implication for ORIF: anterior approach and soft-tissue stripping further compromises the blood supply; preserve the soft-tissue hinge; do not skeletonise the fragment

Ligamentous Anatomy of the Lateral Elbow

Lateral Ulnar Collateral Ligament (LUCL)

• The LUCL is the primary restraint to posterolateral rotatory instability (PLRI)
• Origin: the isometric point on the lateral epicondyle (the centre of the arc of the capitellum)
• Insertion: the supinator crest of the ulna
• The LUCL is the most POSTERIOR component of the lateral collateral ligament complex
• During a Kocher approach (between anconeus and ECU), the LUCL is at risk of detachment from the lateral epicondyle

Radial Collateral Ligament (RCL)

• The RCL originates from the lateral epicondyle and inserts onto the annular ligament
• It is more ANTERIOR than the LUCL
• Less critical to PLRI but contributes to lateral stability

Annular Ligament

• Encircles the radial head, holding it against the radial notch of the ulna
• Originates and inserts on the supinator crest of the ulna
• Preserved during the lateral approach in most cases

Implications for Approach

• The Kocher approach enters between the anconeus (posterior) and the extensor carpi ulnaris (anterior) — the LUCL is in this interval and is at risk
• The Kaplan (extensile lateral column) approach enters between the extensor carpi radialis longus/brevis (anterior) and the extensor digitorum communis (posterior) — it is anterior to the LUCL and spares the ligament
• The choice between Kocher and Kaplan depends on the fracture pattern: Kocher is preferred when the fragment is more POSTEROLATERAL; Kaplan is preferred when the fragment is more ANTERIOR

Anterior Capsule and Coronoid Fossa

• The coronoid fossa lies on the anterior surface of the distal humerus, just proximal to the trochlea
• The radial fossa lies on the anterior surface of the capitellum
• These fossae receive the coronoid and the radial head, respectively, in full flexion
• The anterior capsule inserts just proximal to the coronoid fossa
• During a lateral approach to the capitellum, the anterior capsule may need to be released from the anterior humerus to mobilise the fragment and gain adequate exposure
• Releasing the anterior capsule does NOT produce instability (the anterior capsule is not a primary ligamentous restraint), but it does allow earlier post-operative flexion

Positioning and Preparation

Patient position: Two options are commonly used.

• Supine with arm on a hand table: allows easy fluoroscopy in both AP and lateral planes; the surgeon is seated. The arm is abducted and the elbow is flexed over the hand table. This is the more common position.
• Lateral decubitus with the arm over a bolster: the arm hangs over a padded bolster, allowing the elbow to flex under gravity. Useful for fractures that require more extensive exposure or for combined approaches.

Tourniquet: An upper-arm tourniquet is used. Inflate to 250 mmHg after exsanguination. Tourniquet time is generally limited to 90-120 minutes to minimise the risk of nerve compression palsy.

Anaesthesia: General anaesthesia is standard, with an interscalene block for post-operative analgesia. The patient is examined under anaesthesia before draping to assess stability (varus, valgus, pivot-shift).

Fluoroscopy: Image intensifier is positioned on the opposite side of the table from the surgeon. A true lateral of the elbow is critical — the radiocapitellar joint is best seen on a true lateral with the forearm in neutral rotation.

Consent: Specifically counsel regarding risk of avascular necrosis (0-25% reported, often asymptomatic), stiffness (10-30% require capsular release), post-traumatic arthritis (20-40% radiographic at 5 years), fixation failure (5-10%), ulnar nerve symptoms (1-3%), and posterolateral rotatory instability if the LUCL is not preserved.

Lateral Approach — Step-by-Step

Step 1: Marking the Landmarks

Mark the lateral epicondyle, the radial head, the olecranon, and the lateral border of the extensor mass. Palpate the LUCL origin on the lateral epicondyle — it is the soft spot just proximal and posterior to the epicondyle.

Plan the skin incision: a curved or gently oblique incision centred over the lateral epicondyle, 8-10 cm in length, beginning 3-4 cm proximal to the epicondyle and extending distally over the radiocapitellar joint and the proximal radius.

Step 2: Superficial Dissection and Identification of the LUCL

Incise the skin and subcutaneous fat. Identify the fascia overlying the extensor mass and the anconeus. The interval between the anconeus and the extensor carpi ulnaris (ECU) is the Kocher interval — it overlies the LUCL.

Identify the LUCL as a discrete thickening on the deep surface of the fascia, originating from the lateral epicondyle and inserting on the supinator crest of the ulna. Protect the LUCL throughout the dissection; if it is detached, mark the isometric point for later repair.

Step 3: Deep Dissection — Kocher Interval

Deepen the dissection through the Kocher interval, developing the plane between the anconeus (posterior) and the ECU (anterior). The LUCL is in this plane. Reflect the anconeus posteriorly and the ECU anteriorly.

Identify the annular ligament distally — it encircles the radial head. The annular ligament is often intact in isolated capitellar fractures but may be torn in association with an elbow dislocation or a radial head fracture.

The anterior capsule is now visible, deep to the extensor mass. The capitellar fragment lies anterior to the distal humerus, often rotated and impacted in the coronoid fossa or the radial fossa.

Step 4: Anterior Capsulotomy and Exposure of the Fragment

Incise the anterior capsule longitudinally, in line with the skin incision, beginning just anterior to the lateral epicondyle and extending distally to the radial head. Reflect the anterior capsule off the anterior humerus to expose the anterior aspect of the capitellum.

The capitellar fragment is now visible. It is typically rotated, impacted in the coronoid or radial fossa, and may be partially covered by haematoma. Do not remove any soft-tissue attachments on the deep (anterior) surface of the fragment — this is its only blood supply.

Step 5: Fracture Bed Preparation

Irrigate the fracture bed with normal saline. Remove haematoma and any small loose fragments of cancellous bone that cannot be re-implanted. Inspect the donor site on the distal humerus to assess:

• Size and shape of the defect
• Integrity of the posterior condyle (Dubberley type 1, 2, or 3)
• Presence of any impaction that needs to be reduced

Use a fine curette or a small osteotome to gently elevate any impacted subchondral bone to restore the normal contour of the capitellum.

Step 6: Reduction of the Fragment

Reduce the capitellar fragment onto the donor bed. Use a dental pick or fine K-wire joysticks to manipulate the fragment. The reduction is judged by:

• Visualisation of the articular surface contour (the radial-capitellar joint should be smooth and congruent)
• Palpation of the fracture line at the donor site
• Multi-plane fluoroscopy (AP, lateral, and oblique views)

Provisionally fix the fragment with smooth 0.045 or 0.062 inch K-wires from anterior to posterior or from a non-articular surface. Place the K-wires outside the planned screw trajectory to avoid interference.

Step 7: Definitive Fixation with Headless Compression Screws

Choose the screw size based on the fragment size: 2.0 mm, 2.4 mm, 2.7 mm, or 3.0 mm headless compression screws (Herbert, Acutrak, Mini-Acutrak). Two to three screws are typically placed.

Screw trajectory:

• Anterior-to-posterior (AP): the standard trajectory for Hahn-Steinthal whole-capitellum fragments. The screw entry point is on the anterior (non-articular) surface of the capitellum, just proximal to the radial fossa. The screw exits through the posterior condyle. The threads engage only in the posterior condyle (the differential pitch compresses the fragment).
• Posterior-to-anterior (PA): preferred when the fragment has a clean posterior exit point and the anterior surface of the capitellum is the donor site. The screw entry is through a small posterior cortical window in the condyle.

Technique for AP screw placement:

• Place a guide wire from anterior to posterior under fluoroscopic control
• Confirm wire position on AP, lateral, and oblique fluoroscopy
• Measure screw length
• Drill over the guide wire with the cannulated drill
• Insert the headless compression screw over the guide wire
• Confirm screw position with fluoroscopy — the screw head must be BURIED beneath the articular cartilage (countersunk) and the screw must not penetrate the posterior cortex into the olecranon fossa
• Remove the guide wire and the provisional K-wires
• Repeat for additional screws (typically a second screw from a divergent trajectory)

Step 8: Assessment of Fixation Stability

Test the fixation by taking the elbow through a full range of motion under direct vision. The fragment should be stable, with no visible motion at the fracture line. If motion is present, consider:

• Adding a third screw
• Using a mini-fragment plate as a buttress on the posterior condyle
• Using a suture anchor or trans-osseous suture for additional fixation

Confirm stability with multi-plane fluoroscopy at the extremes of motion (full flexion, full extension, and pronation/supination).

Step 9: Assessment of Ligamentous Stability

Test the elbow for stability:

• Varus and valgus stress under fluoroscopy — look for joint-space opening
• Pivot-shift test (lateral pivot-shift apprehension test) under anaesthesia — the forearm is supinated and an axial load is applied while the elbow is brought from extension to flexion; a positive test produces a palpable clunk as the radius and ulna subluxate posteriorly on the humerus
• If the LUCL has been detached, reattach it through trans-osseous bone tunnels in the lateral epicondyle at the isometric point, using a heavy non-absorbable suture
• If the medial collateral ligament has been injured (rare in isolated capitellar fractures), address it through a separate medial approach

Step 10: Management of Associated Injuries

• Radial head fracture: if a non-reconstructable Mason III radial head fracture is present, perform a radial head replacement (metallic radial head arthroplasty) in the same setting. Do not excise the radial head — this produces proximal radial migration and wrist pain.
• Coronoid fracture: a small tip fracture (Regan-Morley type I) can usually be left alone if the elbow is stable. Larger fractures (type II-III) may need fixation through a separate medial approach.
• Elbow dislocation: if the elbow was dislocated at presentation, the medial collateral ligament and the anterior capsule are often torn. These usually heal with functional bracing if the elbow is stable after fixation of the bony injury.

Step 11: Closure

Irrigate the wound. Close the anterior capsule loosely with absorbable sutures (it is not a primary ligamentous restraint). Reattach the LUCL to the lateral epicondyle if it has been detached. Close the Kocher interval with absorbable sutures. Insert a suction drain if extensive dissection has been performed. Close the skin with non-absorbable sutures or staples. Apply a sterile dressing and a back-slab in 60-90 degrees of flexion with the forearm in neutral rotation.

Alternative Approaches

Extensile Lateral Column (Kaplan) Approach

• Indicated when the fragment is more ANTERIOR (less posterolateral) and a single anterior exposure is preferred
• Interval: between the extensor carpi radialis brevis (anterior) and the extensor digitorum communis (posterior)
• The Kaplan interval is ANTERIOR to the LUCL, sparing the ligament
• May be combined with a small anterior capsulotomy for fragment access
• Useful when the surgeon does not want to detach the LUCL

Posterior Approach (for Posterior Comminution — Dubberley Type 2-3)

• Indicated when there is extensive posterior condylar comminution that requires a buttress plate
• The patient is positioned in lateral decubitus or prone
• A midline posterior skin incision is made; the ulnar nerve is identified and protected
• The triceps is reflected (Bryan-Morrey triceps-sparing approach, or olecranon osteotomy for extensive exposure)
• The posterior condyle is exposed for plate fixation
• Often combined with a separate lateral approach for the anterior coronal shear fragment

Medial Approach (for Coronoid / Medial Column)

• Indicated when there is a coronoid fracture that requires fixation, or when there is a medial column injury
• The ulnar nerve is identified and protected
• The medial collateral ligament is identified and protected
• The coronoid is exposed through the floor of the cubital tunnel or through a separate flexor-pronator split

Post-operative Protocol

Early Phase (Day 0-14)

• Back-slab in extension 24-48 hours: a back-slab in near-full extension reduces swelling and prevents the contracture that would otherwise develop in flexion. The splint is removed for active assisted ROM exercises from day 2.
• Active assisted ROM: begin the day after surgery, with the physiotherapist supervising. The patient is encouraged to achieve the maximum arc of motion achievable.
• Elevation: elevate the arm above heart level for the first 48-72 hours to minimise swelling.
• Analgesia: paracetamol and NSAIDs; opioids as required. An interscalene block at the time of surgery provides excellent early analgesia.
• Wound check at 48 hours and 10-14 days. Suture removal at 10-14 days.
• Heterotopic ossification prophylaxis: indomethacin 25 mg orally three times daily for 3-6 weeks in patients at high risk (head injury, burn injury, recurrent surgery, severe soft-tissue injury). Single-dose radiation therapy (700-800 cGy) within 72 hours of surgery is an alternative for high-risk patients.

Intermediate Phase (Week 2-6)

• Progressive active assisted and passive ROM: supervised by a hand or upper-limb physiotherapist. The goal is to achieve a functional arc (30-130 degrees) by 6 weeks.
• Strengthening: begin gentle isometric strengthening at 4-6 weeks. Resistive exercises begin at 6-8 weeks.
• Static progressive splinting: consider a static progressive flexion or extension splint (e.g. turnbuckle splint) if motion is plateauing at 4-6 weeks.
• Imaging: AP and lateral x-rays at 2 weeks, 6 weeks, 12 weeks, and 6 months to assess healing, hardware position, and for evidence of AVN or post-traumatic arthritis.

Return to Function

• Light activities: From week 2-3
• Driving: When safe to grip the steering wheel (typically 4-6 weeks)
• Return to sedentary work: 2-4 weeks
• Return to heavy manual work: 3-6 months
• Return to sport: 4-6 months for non-contact; 6-9 months for contact or overhead sport

Rehabilitation Milestones

• 6 weeks: functional arc of 30-130 degrees in the majority
• 3 months: approximately 80% of final motion achieved
• 6 months: plateau of motion; further improvement is unusual
• 12 months: end-result for most patients; residual loss of 10-30 degrees of terminal flexion or extension is common

Special Case: Dubberley Type 2-3 (Posterior Comminution)

Defining the Problem

• Dubberley type 2 = posterior condyle is comminuted
• Dubberley type 3 = fracture line extends through the posterior condyle
• The posterior condyle cannot be relied upon for screw purchase or for containing the anterior fragment
• The fragment is at high risk of fixation failure, re-displacement, and AVN

Surgical Strategy

• Two-incision approach: lateral approach for the anterior coronal shear fragment; medial or posterior approach for the posterior condyle
• The posterior condyle is fixed with a buttress plate (mini-fragment or precontoured distal humeral plate) applied through a posterior approach
• The anterior fragment is fixed with headless compression screws from anterior to posterior
• Consider bone grafting the comminuted posterior condyle to provide structural support

Outcomes

• Higher re-operation rate for stiffness and hardware removal
• Higher rate of post-traumatic arthritis
• Counsel the patient preoperatively about the more guarded prognosis

Special Case: Capitellar Fracture with Associated Radial Head Fracture

Defining the Problem

• The same axial load that produces the coronal shear often drives the radial head into the capitellum, producing a Mason II or III radial head fracture
• The combination is sometimes called a 'Mason IV' pattern (radial head fracture with elbow dislocation) or a 'capitellar-radial head' injury
• Both the radiocapitellar and the ulnohumeral joints are injured

Surgical Strategy

• Plan a single-stage procedure: lateral approach for both the capitellar fragment and the radial head
• Fix the capitellum first (it is the larger reconstructable surface)
• Address the radial head second:
  • Mason II (single fragment, greater than 2 mm displaced): ORIF with mini-fragment screws
  • Mason III (comminuted): if non-reconstructable, perform a metallic radial head arthroplasty. Do not excise the radial head — this produces proximal radial migration and wrist pain
• Assess ligamentous stability at the end of the procedure
• If the elbow is unstable, the LCL (lateral collateral ligament) needs to be repaired; consider a medial repair or a hinged external fixator in severe cases

Outcomes

• Combined injuries have a higher rate of post-traumatic arthritis than isolated capitellar fractures
• Stiffness and heterotopic ossification are more common
• Counsel the patient about the more guarded prognosis

Special Case: The Low-Demand Elderly Patient with Comminuted Non-Reconstructable Fracture

Defining the Problem

• A patient older than 70 years, low-demand (sedentary, no heavy manual work, no sport), with a comminuted capitellar and trochlear fracture that cannot be reconstructed
• ORIF would require multiple screws, plates, and bone graft with prolonged surgery and uncertain outcome

Surgical Strategy

• Consider acute fragment excision with early mobilisation as the primary procedure
• Consider acute total elbow arthroplasty in the very low-demand patient with extensive comminution (this is a salvage option; the patient must be counselled about activity restrictions)
• A 'functional elbow' with a painless, stable arc of motion in a useful range (30-130 degrees) is the goal — not anatomic restoration of the articular surface

Outcomes

• Fragment excision alone: acceptable outcomes in low-demand patients; some loss of grip strength and stability
• Total elbow arthroplasty: good pain relief and functional range; permanent lifting restriction of 5 kg