Surgical technique guide for Cubitus Varus Correction (Supracondylar Osteotomy) - FRCS exam preparation
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Orthopaedic clinicians and medical editors • Published by OrthoVellum Medical Education Team
Lateral approach (Kocher interval) or posterior approach | advanced
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.
Location: Posterior to medial epicondyle in cubital tunnel. Protection: For posterior approach or medial hinge completion, identify and protect with vessel loop if necessary.
Location: Continuation of musculocutaneous nerve, lateral to biceps tendon at elbow crease. Protection: Protect during anterior dissection; injury causes lateral forearm numbness.
Location: Anteromedial to distal humerus in antecubital fossa. Protection: Keep anterior periosteum intact as barrier. Avoid anterior dissection or penetrating anterior cortex with osteotome.
Location: 1-2cm distal to osteotomy site in skeletally immature patients. Protection: Maintain osteotomy at supracondylar level, proximal to olecranon fossa.
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
Etiology:
Deformity Components (3D):
Clinical Assessment:
Radiographic Parameters:
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
| heading | column1 | column2 | column3 |
|---|---|---|---|
| Complication | Recognition | Prevention | Management |
| Ulnar Nerve Injury | Medial-sided numbness, weak grip, clawing of ring/little fingers | Palpate nerve before medial K-wire, flex elbow during wire insertion, start wire anterior to epicondyle | Observation 3 months if neuropraxia; exploration and release if no recovery; nerve repair if transected |
| Under/Over-Correction | Carrying angle not matching contralateral side at follow-up | Precise preoperative templating, intraoperative comparison to normal side, check Baumann angle | Revision osteotomy if deformity unacceptable; accept minor over-correction (5° valgus) over residual varus |
| Loss of Fixation | Change in carrying angle on serial XR, K-wire migration, plate loosening | Adequate K-wire purchase (cross at osteotomy), plate with 6+ screws, proper cast immobilization | Re-fixation if early; accept malunion or plan revision osteotomy if consolidated |
| Lateral Condyle Prominence | Visible/palpable bump at lateral elbow, cosmetic concern | Lateral closing wedge inherently creates prominence; consider dome osteotomy for severe cases | Reassurance (usually acceptable); bone trimming at hardware removal if symptomatic |
| Pin Site Infection | Erythema, purulent discharge, pain at K-wire entry site | Daily pin site care, antibiotics prophylaxis controversial, early wire removal at union | Oral antibiotics for superficial; IV antibiotics and wire removal for deep; curettage if osteomyelitis |
| Elbow Stiffness | Loss of flexion-extension arc greater than 20° compared to preoperative | Avoid prolonged immobilization, start ROM at 6 weeks, aggressive physiotherapy | Intensive physiotherapy; static progressive splinting; arthroscopic release if persistent beyond 6 months |
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.
Practice these scenarios to excel in your viva examination
"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?"
"Describe the surgical technique for lateral closing wedge osteotomy. How do you prevent ulnar nerve injury during K-wire fixation?"
"What is the relationship between cubitus varus and posterolateral rotatory instability? How does this influence your management?"
High-Yield Exam Summary
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