Supracondylar Humerus Fracture Reduction and Fixation: Key Steps and Essential Tips

Supracondylar humerus fractures are common in pediatric patients. Most displaced fractures require surgical reduction and K-wire fixation. This article aims to help understand and master this common fracture by covering indications, preoperative preparation, surgical methods, and technical points for pediatric supracondylar humerus fractures.

Indications

- Significant displacement and angulation of the distal humerus supracondylar fracture.

- Minimally or non-displaced fractures with medial impaction (risk of cubitus varus).

- Minimally or non-displaced fractures with medial impaction, but accompanied by other injuries (e.g., neurovascular injury, compartment syndrome, complex fractures, or soft tissue defects).

Contraindications

- Evidence of ischemia in the upper extremity, where open exploration indicates that reduction cannot restore perfusion.

Preoperative Preparation

Physical examination includes:

1. Assessment of skin integrity and ecchymosis.

2. Evaluation of the "dimple sign" from muscle impingement by fracture fragments.

3. Distal pulse (palpation and/or Doppler) and perfusion analysis.

4. Distal neurological function assessment.

5. Evaluation for signs of compartment syndrome.

Imaging: AP and lateral elbow radiographs; if necessary, obtain radiographs of the contralateral elbow.

Initial management: Suspend and immobilize the affected limb (avoid hyperflexion of the elbow).

Urgent treatment indicated for: Anterior elbow abrasions, excessive swelling, high compartment pressure, skin puckering, or poor hand perfusion.

If non-emergent treatment is planned: Close observation with repeated examinations of distal limb motor, sensory, and vascular status.

Note: Most fractures are suitable for lateral pin placement without the need for medial pins. Biomechanical studies have shown that lateral-only pin fixation provides similar stability to crossed pin fixation.

Positioning and Anesthesia

- The patient lies supine on the operating table, with the ipsilateral shoulder at the table edge. Use a fixation strap and consider securing the patient's head.

- The patient's arm is placed on a C-arm, using the C-arm table as the surgical platform. The elbow should be positioned at the center of the C-arm table.

- For unstable fractures, surgery can be performed with the arm extended on a radiolucent arm board. Rotate the fluoroscopy unit to obtain AP and lateral views, avoiding rotation of the arm to prevent loss of reduction.

- General anesthesia is preferred intraoperatively. The anesthesiologist should be aware that significant traction may be applied to the upper extremity during reduction.

Surgical Technique

Position the patient appropriately. Prepare and drape from axilla to fingers. Do not use an upper arm tourniquet. If open reduction is required, a sterile tourniquet may be used.

Suspend the injured arm on an inverted C-arm, or alternatively place it on a radiolucent arm board.

Document distal neurovascular findings before attempting reduction.

Fracture Reduction:

- Step 1: Apply longitudinal traction with the elbow flexed to 15°. This prevents neurovascular injury from the fracture ends during reduction and restores limb length. If the proximal fragment has penetrated the brachialis muscle (positive "dimple sign"), use a "milking" maneuver to extract the bone from the muscle.

- Step 2: Correct medial or lateral displacement.

- Step 3: Correct rotational deformity before reducing the fracture ends. Typically, external rotation of the distal fragment is required.

- Step 4: Gently press forward on the olecranon and extend the elbow to correct the extension deformity. Confirm adequate reduction on AP (Baumann's angle >10°), oblique (intact medial and lateral columns), and lateral views (anterior humeral line intersecting the capitellum).

Figure A: Distal humerus fracture – AP view. Step 1: Longitudinal traction to over-distract the distal fragment.   

Figure B: Distal humerus fracture – Lateral view. Flex the elbow and gently press forward on the olecranon to correct extension.

Lateral K-wire Placement

- After hyperflexing the elbow, percutaneously insert a pin (typically 0.062-inch K-wire) into the cartilage. Check AP and lateral views to confirm satisfactory entry point.

- Drive the pin from the distal aspect of the lateral condyle, angling medially and proximally.

- Goal: Maximize pin spread at the fracture site to engage both the medial and lateral columns.

- Advance the pin through the distal fragment, across the fracture line, and into the opposite cortex of the proximal fragment.

Figure A: Lateral pin insertion – lateral view. With the elbow flexed, place the pin against the distal aspect of the lateral humeral condyle, angling medially and proximally.   

Figure B: Lateral pin insertion – AP view (elbow flexed). The pin passes through the distal fragment, across the fracture line, and into the opposite cortex of the proximal fragment.

- Ensure adequate bone purchase in both proximal and distal fragments.

- Use 2 pins for Gartland type II (angulated with intact posterior cortex) and 3 pins for Gartland type III (completely displaced) fractures.

- Pins may be placed parallel or divergently.

Medial K-wire Placement

- Most fractures are sufficiently stabilized with lateral-only pins.

- A medial pin may be needed if there is an oblique fracture or medial comminution.

- Place lateral pins first. Extend the elbow to 45° before inserting the medial pin to reduce the risk of ulnar nerve injury.

- Palpate and protect the ulnar nerve. If severe swelling obscures bony landmarks, make a 4-mm true skin incision distal to the medial epicondyle and dissect directly to bone.

- Insert the K-wire onto the bone surface between the two arms of a mosquito clamp.

Figure: Medial pin insertion – AP view. If a medial pin is required, insert it with the elbow in extension. Make a small skin incision distal to the medial epicondyle. Use a hemostat to bluntly dissect to bone, then advance the pin along the hemostat to the distal bone surface.

- Drive the pin across the fracture site to the opposite cortex, ensuring pins do not cross at the fracture site.

- Finally, re-check reduction, fixation, and vascular function.

- Bend the pin ends, taking care not to pull the pins out of the opposite cortex. Cut the pins close to the skin and cover with sterile gauze.

Suggestions and Key Points

- Preoperative careful neurovascular assessment is paramount, especially pulse, capillary refill, and anterior interosseous nerve branch function.

- If vascular examination worsens after closed reduction, pause and proceed to open exploration and reduction.

- If medial pin placement is needed, keep the elbow extended to protect the ulnar nerve. If swelling obscures landmarks, consider a skin incision and blunt dissection to bone.

- Ensure the pins engage as much bone as possible across the fracture.

Pitfalls and Traps

- Avoid vascular injury during fracture reduction.

- Avoid ulnar nerve injury when placing K-wires.

- Avoid failing to engage the opposite cortex.

- Avoid pin crossing at the fracture line. Lateral pins should exit the skin laterally; crossed pins should cross proximal to the fracture line.

Postoperative Care

- Apply a cast or splint with the elbow flexed to 90° or slightly less.

- Elevate the affected limb for 12–48 hours postoperatively, with the elbow above the heart and hand above the elbow.

- Frequently check neurovascular function postoperatively, watching for changes and development of compartment syndrome.

- If ulnar nerve symptoms develop, remove the medial pin and extend the elbow.

- Remove K-wires 3–4 weeks postoperatively.