High Yield Overview

CUBITUS VARUS CORRECTION (SUPRACONDYLAR OSTEOTOMY)

Lateral approach (Kocher interval) or posterior approach | advanced

Mnemonic

VARUSVARUS - Planning Correction

Mnemonic

WEDGEWEDGE - Osteotomy Principles

Critical Danger Structures

Radial Nerve (Posterior Interosseous)

Location: Exits lateral intermuscular septum 10cm proximal to lateral epicondyle, wraps around radial neck. Protection: Stay subperiosteal on lateral humerus, avoid dissection distal to lateral epicondyle.

Ulnar Nerve

Location: Posterior to medial epicondyle in cubital tunnel. Protection: For posterior approach or medial hinge completion, identify and protect with vessel loop if necessary.

Lateral Antebrachial Cutaneous Nerve

Location: Continuation of musculocutaneous nerve, lateral to biceps tendon at elbow crease. Protection: Protect during anterior dissection; injury causes lateral forearm numbness.

Brachial Artery and Median Nerve

Location: Anteromedial to distal humerus in antecubital fossa. Protection: Keep anterior periosteum intact as barrier. Avoid anterior dissection or penetrating anterior cortex with osteotome.

Lateral Epicondylar Growth Plate

Location: 1-2cm distal to osteotomy site in skeletally immature patients. Protection: Maintain osteotomy at supracondylar level, proximal to olecranon fossa.

Positioning and Preparation

Patient Position: Supine with arm across chest or on arm board, upper arm tourniquet

Surgical Approach: Lateral approach (Kocher interval) or posterior approach

Incision: 8-10cm lateral incision centered over lateral epicondyle or posterior midline over distal humerus

Understanding Cubitus Varus Deformity

Etiology:

Supracondylar fracture malunion (most common - 30% if inadequately treated)
Lateral condyle nonunion with overgrowth
Physeal arrest
Congenital

Deformity Components (3D):

Coronal: Varus angulation (loss of carrying angle)
Sagittal: Extension or hyperextension (loss of anterior humeral line)
Axial: Internal rotation of distal fragment

Clinical Assessment:

Carrying angle measured with elbow extended, forearm supinated
Normal: 5-15° valgus (greater in females)
Cubitus varus: 0° or negative carrying angle
Compare to contralateral side

Radiographic Parameters:

Baumann angle: Normal 70-75° (decreased in varus)
Humeral-capitellar angle: Normal 5-15° valgus
Anterior humeral line: Should pass through middle third of capitellum

Operative Technique

Step 1: Preoperative planning and template preparation

Preoperative planning and template preparation: Measure carrying angle on both sides clinically (elbow extended, forearm supinated). Review AP and lateral radiographs of both elbows. Measure varus deformity angle (difference from normal contralateral side). Calculate wedge angle: varus angle + desired valgus (typically 10°). Template osteotomy on radiograph - mark wedge base laterally, apex medially. Calculate wedge base width: 2 × sin(wedge angle) × bone diameter at osteotomy level. Assess sagittal plane for extension component. Assess rotation clinically for internal rotation. Prepare K-wires (1.6-2.0mm), oscillating saw, and fixation implants.

Exam Pearl

Technical Tip: EXAM KEY: Use contralateral normal elbow as the target. If 15° varus deformity and target is 10° valgus, wedge angle = 25°. Template precisely on paper before surgery.

Dangers at this step

Under-planning leads to under-correction or over-correction. Measure angles on standardized radiographs with elbow in true AP position. Missing rotational component is common error - assess clinically by comparing shoulder rotation with elbow flexed.

Step 2: Patient positioning, tourniquet application, and preparation

Patient positioning, tourniquet application, and preparation: Position supine on radiolucent table. Arm on arm board or hand table with shoulder abducted 90°, elbow accessible for lateral approach. Apply upper arm tourniquet (250-300mmHg for child). Position C-arm from opposite side for AP and lateral views. Check fluoroscopy access before prepping - ensure true AP and lateral obtainable. Prep and drape entire arm from shoulder to fingertips. Mark lateral epicondyle, olecranon, and planned 8-10cm lateral incision.

Exam Pearl

Technical Tip: EXAM KEY: Arm position must allow both AP and lateral fluoroscopy. Check before draping - reposition if views inadequate.

Dangers at this step

Tourniquet on too long (limit to 90 minutes). Fluoroscopy access inadequate once draped - check views before prepping. Sterile prep must include area for K-wire placement medially and laterally.

Step 3: Lateral approach to distal humerus

Lateral approach to distal humerus: Make 8-10cm straight lateral incision centered over lateral supracondylar ridge, starting proximal to lateral epicondyle. Incise skin and subcutaneous tissue. Identify lateral intermuscular septum. Develop plane between triceps posteriorly and brachioradialis/brachialis anteriorly (modified Kocher interval). Subperiosteal elevation on lateral and posterior humerus at supracondylar level (1-2cm proximal to olecranon fossa). Protect soft tissues anteriorly (brachial artery and median nerve) by maintaining intact anterior periosteum. Identify and protect radial nerve proximally if dissection extends greater than 8cm proximal to lateral epicondyle.

Exam Pearl

Technical Tip: EXAM KEY: The lateral intermuscular septum is the key structure - radial nerve pierces it 10cm proximal to epicondyle. Stay on bone subperiosteally at osteotomy site.

Dangers at this step

Radial nerve injury (exits septum 10cm proximal) - limit proximal dissection. Brachial artery and median nerve anterior - keep anterior periosteum intact. Do not dissect distal to epicondyle (physis and PIN at risk).

Step 4: Mark osteotomy site and place guide K-wires

Mark osteotomy site and place guide K-wires: Identify osteotomy site at supracondylar level (1-2cm proximal to olecranon fossa, proximal to growth plates in children). Place first guide K-wire perpendicular to humeral shaft from lateral cortex - this marks the distal cut. Place second K-wire at the calculated wedge angle proximally (this marks the proximal cut). The angle between wires equals the planned correction. Confirm position with AP and lateral fluoroscopy - wires should be at supracondylar level, proximal to olecranon fossa and capitellum. If rotation correction needed, mark rotational position on cortex with osteotome scratches.

Exam Pearl

Technical Tip: EXAM KEY: Guide K-wires are critical for precise correction. The angle between them is the correction angle. Check with goniometer if unsure.

Dangers at this step

Osteotomy too distal - violates joint or olecranon fossa. Osteotomy too proximal - cosmetic deformity at different level. K-wires not in same plane - creates unintended rotational or sagittal malalignment.

Step 5: Perform lateral closing wedge osteotomy

Perform lateral closing wedge osteotomy: Using oscillating saw, make first (distal) cut perpendicular to humeral shaft along the distal K-wire. Keep anterior periosteum intact (protects neurovascular bundle). Extend cut to but not through medial cortex - leave medial hinge intact. Make second (proximal) cut along proximal K-wire, converging toward medial cortex. Remove the lateral-based wedge of bone. Save bone wedge as possible graft. The wedge should have its base laterally and apex at the intact medial hinge. Copiously irrigate to remove bone debris.

Exam Pearl

Technical Tip: EXAM KEY: Medial hinge is critical - provides stability, prevents translation, and acts as a pivot point for correction. If medial cortex cuts through, osteotomy becomes unstable.

Dangers at this step

Saw generating heat - irrigate during cutting to prevent thermal necrosis. Anterior cortex penetration - exposes neurovascular bundle to saw blade. Complete medial cortex cut - loses hinge stability. Saw blade bending in bone - can break.

Step 6: Close osteotomy and correct deformity

Close osteotomy and correct deformity: Gently close the osteotomy by adducting the forearm (varus stress to distal fragment). The medial hinge should act as a pivot point, allowing the lateral gap to close. Apply gradual pressure until lateral cortices oppose. Check alignment clinically - elbow extended, forearm supinated - assess carrying angle. Compare to contralateral side intraoperatively. If rotation correction required, rotate distal fragment externally before closing osteotomy. If hyperextension correction needed, flex distal fragment slightly before closing. Confirm correction with fluoroscopy - Baumann angle should match contralateral side.

Exam Pearl

Technical Tip: EXAM KEY: Check carrying angle with elbow fully extended and forearm supinated - this is the clinical measure that matters. Intraoperative comparison to contralateral side is essential.

Dangers at this step

Over-correction to valgus (worse than leaving varus). Medial hinge cracks - creates translation and instability. Not correcting rotation if present - leaves internal rotation deformity. Not checking sagittal plane - may create hyperextension.

Step 7: Temporary fixation with K-wires and fluoroscopic confirmation

Temporary fixation with K-wires and fluoroscopic confirmation: Maintain reduction manually. Insert first K-wire (1.6-2.0mm) from lateral epicondyle, directing proximally and medially across osteotomy. Insert second K-wire from medial epicondyle, directing proximally and laterally across osteotomy (identify and protect ulnar nerve by palpation - wire anterior to nerve). Wires should cross at osteotomy site. Consider third lateral wire for additional stability. Confirm position on AP and lateral fluoroscopy. Check Baumann angle (should match contralateral), carrying angle clinically, and osteotomy apposition.

Exam Pearl

Technical Tip: EXAM KEY: Medial wire at risk for ulnar nerve - palpate nerve, flex elbow to move nerve posteriorly, insert wire with elbow flexed then extend for fluoroscopy. Start wire anterior to medial epicondyle.

Dangers at this step

Ulnar nerve injury from medial K-wire (most common technical error). Wires not crossing at osteotomy - reduces construct stability. Pins too superficial - not engaging proximal fragment cortex. Loss of reduction during wire insertion.

Step 8: Definitive fixation - K-wires or plate

Definitive fixation: For K-wire fixation (most common in children): Bend and cut wires percutaneously 1cm from skin. Apply dressing and above-elbow backslab at 90° flexion. K-wires removed at 4-6 weeks. For plate fixation (adolescents/adults): Apply lateral column plate (3.5mm LCP or recon plate). Minimum 3 screws proximal, 3 screws distal to osteotomy. Contour plate to match lateral humeral anatomy. Unicortical or carefully placed bicortical screws to avoid anterior neurovascular structures. Check ROM intraoperatively - should be near-full flexion-extension.

Exam Pearl

Technical Tip: EXAM KEY: K-wires for children (simple, effective, low profile). Plates for adolescents/adults (allows early mobilization). Plate requires second surgery for removal but permits earlier ROM.

Dangers at this step

Anterior cortex screw penetration - risks brachial artery and median nerve. Plate prominence - may require removal in thin patients. Over-contouring plate - can alter correction achieved.

Step 9: Wound closure and immobilization

Wound closure and immobilization: Release tourniquet. Achieve hemostasis with bipolar cautery. Irrigate wound thoroughly with saline. Close periosteum if possible with 2-0 absorbable suture. Close deep fascia and subcutaneous layer with 3-0 absorbable sutures. Close skin with 4-0 subcuticular absorbable suture or nylon. Apply sterile dressings. Apply well-padded above-elbow posterior splint or cast at 90° elbow flexion. Ensure adequate padding over K-wire sites if percutaneous. Check distal pulses, capillary refill, and finger movement before leaving OR.

Exam Pearl

Technical Tip: EXAM KEY: Position elbow at 90° flexion in splint - this is the functional position and protects the osteotomy. Check neurovascular status after cast application.

Dangers at this step

Tight cast causing compartment syndrome (especially in children). Hematoma if hemostasis inadequate. K-wire sites insufficiently padded - skin breakdown. Loss of reduction if cast too loose.

Step 10: Final fluoroscopic documentation and postoperative planning

Final fluoroscopic documentation and postoperative planning: Obtain final AP and lateral fluoroscopic images in cast/splint. Document Baumann angle (should match contralateral normal). Confirm K-wire or plate position adequate. Compare carrying angle to preoperative measurement - document correction achieved. Plan postoperative care: K-wires out at 4-6 weeks, cast for 4-6 weeks total, ROM exercises starting at 6 weeks. Document for operative report: wedge angle, degree of correction achieved, fixation used, neurovascular status at end of case.

Exam Pearl

Technical Tip: EXAM KEY: Documentation of correction angle and Baumann angle is important for medicolegal purposes and follow-up comparison.

Dangers at this step

Inadequate documentation - always record preoperative and postoperative angles. Failure to check neurovascular status in final cast - compartment syndrome can develop early. Not arranging appropriate follow-up - pin site care and wire removal timing critical.

Complications

Cubitus Varus Correction Complications - Recognition and Management

Post-operative Care

Above elbow posterior splint at 90 degrees for 5-7 days. Convert to cast once swelling subsided. Immobilization 4-6 weeks (plate) or 6-8 weeks (K-wires). K-wire removal at 6-8 weeks. Begin active-assisted ROM after immobilization - gentle flexion/extension, avoid varus-valgus stress. Physiotherapy for ROM and strengthening at 8-10 weeks. Radiographs at 2, 6, 12 weeks. Plate removal at 6-12 months after union. Full activity at 3-4 months once union solid and ROM restored.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 10-year-old presents 2 years after a supracondylar fracture with an obvious gunstock deformity. The parents are concerned about appearance and function. How do you assess and counsel this family?"

EXCEPTIONAL ANSWER

I would take a focused history including details of the original injury, treatment received, and current functional concerns. On examination, I would assess carrying angle with the elbow extended and forearm supinated - comparing to the contralateral normal side. Normal is 5-15 degrees of valgus; cubitus varus shows a negative angle. I would assess the three planes of deformity: coronal (varus angle), sagittal (hyperextension if present), and axial (internal rotation by comparing forearm position with shoulder rotation). I would check elbow ROM and stability, specifically for posterolateral rotatory instability which can develop secondary to varus. Radiographs would include AP and lateral of both elbows. I would measure Baumann angle (normal 70-75 degrees) and anterior humeral line. For counseling, I would explain that cubitus varus is primarily a cosmetic deformity that does not resolve with growth. Functional issues are uncommon but include altered throwing mechanics. The main late complication is PLRI from chronic lateral column overload. Surgery is elective - a lateral closing wedge osteotomy with K-wire or plate fixation has predictable results with 90 percent or greater correction maintained.

VIVA SCENARIOStandard

EXAMINER

"Describe the surgical technique for lateral closing wedge osteotomy. How do you prevent ulnar nerve injury during K-wire fixation?"

EXCEPTIONAL ANSWER

The lateral closing wedge osteotomy is performed through a lateral approach. I would position the patient supine with the arm on a hand table. After tourniquet application, I make an 8-10cm lateral incision over the supracondylar ridge. I develop the plane between triceps posteriorly and brachioradialis anteriorly, staying subperiosteal at the osteotomy site. The osteotomy is placed 1-2cm proximal to the olecranon fossa, proximal to the physes. I place two guide K-wires: the distal wire perpendicular to the shaft, and the proximal wire at the calculated wedge angle. The angle between them equals the correction. Using an oscillating saw, I cut along both wires, leaving the medial hinge intact - this is critical for stability. I remove the lateral-based wedge, close the osteotomy by adducting the forearm, and check correction clinically by comparing carrying angle to the normal side. For K-wire fixation, the ulnar nerve is at risk during medial wire placement. To protect it, I palpate the nerve posteriorly, flex the elbow to move the nerve further posterior, start the wire anterior to the medial epicondyle, and insert with the elbow flexed before extending for fluoroscopy. I use 2-3 crossed wires engaging both cortices, with the wires crossing at the osteotomy site.

VIVA SCENARIOStandard

EXAMINER

"What is the relationship between cubitus varus and posterolateral rotatory instability? How does this influence your management?"

EXCEPTIONAL ANSWER

Cubitus varus and PLRI are linked through altered elbow biomechanics. In the normal elbow, the carrying angle distributes forces evenly across medial and lateral columns. With cubitus varus, the loading axis shifts laterally, placing increased stress on the lateral collateral ligament complex (LUCL in particular). Over time, this chronic lateral column overload leads to progressive LCL insufficiency and PLRI. PLRI typically presents years after the original injury with lateral elbow pain, clicking, and instability when pushing up from a seated position. The lateral pivot shift test or apprehension is positive. This influences management in several ways. First, PLRI is an additional indication for varus correction - correcting alignment reduces lateral column loading and may prevent further LCL deterioration. Second, if PLRI is established, varus correction alone may be insufficient - the patient may need simultaneous LCL reconstruction (O'Driscoll technique with graft). Third, early correction of cubitus varus before PLRI develops is preferable to prevent irreversible ligament damage. Fourth, during informed consent, I counsel patients that uncorrected varus may lead to instability in adulthood.