Chapter 15

Supracondylar Humeral Osteotomy for Correction of Cubitus Varus

 

Yi-Meng Yen Richard E. Bowen Norman Y. Otsuka

 

DEFINITION

Cubitus varus is a deformity of the distal humerus that results in a change in the carrying angle from physiologic valgus alignment between the upper arm and forearm.

Historically, before modern pinning techniques, cubitus varus was the most common complication following supracondylar humerus fracture, with an average reported frequency of 30%, with rates as high as 60%.

The appearance of the deformity is the major concern for the parents and patient, as there is little functional deficit.4

 

 

ANATOMY

 

Bone

 

 

 

The distal humerus consists of two structural columns of bone medially and laterally. The olecranon and coronoid fossae separate the two structural columns.

 

The cortices of the distal humerus are thinner in the child than the adult, and the anteroposterior (AP) diameter of the distal humerus is decreased in children.

 

Neurovascular

 

 

The median nerve and brachial artery run along the medial border of the biceps brachii muscle in the upper arm and come to lie anterior and slightly medial in the cubital fossa.

 

The radial nerve enters the anterior compartment of the arm in the distal third of the upper arm and travels between the brachialis and brachioradialis over the anterolateral distal humerus before it enters the supinator muscle in the proximal forearm. There have been reports of the radial nerve enclosed within the callus of a supracondylar fracture.

 

PATHOGENESIS

 

Cubitus varus occurs predominantly because of a malunited supracondylar humerus fracture. Unequal growth of the distal humerus can cause cubitus varus, particularly medial physeal growth arrest.

 

The primary cause is coronal varus angulation of the distal humeral metaphysis.

 

Varus angulation can be caused by medial column comminution, causing the fracture to collapse into varus. Varus angulation can rarely be caused by lateral gaping at the fracture site.

 

Other coexisting deformities can exist with cubitus varus, including extension and internal rotation of the distal

fragment.7

 

NATURAL HISTORY

 

The deformity is usually static and does not evolve with time, unless caused by a medial physeal disturbance.

 

The deformity is often not appreciated until several months after the fracture heals and the elbow flexion contracture that results from casting resolves.

 

Tardy ulnar nerve palsy may occur, owing to compression by chronic malpositioning of the triceps muscle due to a shift of the olecranon in the olecranon fossa.

 

Significant cubitus varus may contribute to elbow discomfort and posterolateral rotatory instability.

 

 

There may be a slight increased risk of subsequent lateral condyle fractures in children with cubitus varus.1

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

A detailed history is essential to understand parental and patient expectations of treatment in cubitus varus.

 

Physical findings include a varus change in the carrying angle when compared to the opposite, unaffected side.

 

Elbow and forearm range of motion should be documented.

 

 

A thorough examination of nerve function to the forearm and hand should be performed. Hyperextension of the elbow indicates coexisting extension deformity at the malunion site.

 

A loss of external rotation can be due to shoulder pathology or due to an internal rotation malunion at the distal humerus.

 

The difference in carrying angle between the affected and unaffected side is the amount of cubitus varus.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Plain AP and lateral radiographs of the affected elbow should be obtained (FIG 1).

 

Additionally, an AP radiograph of the affected and unaffected elbow in full extension and supination that includes the distal humerus, forearm, and wrist should be obtained. This is used to plan the amount of surgical correction desired.

 

Advanced imaging (magnetic resonance imaging [MRI] of the elbow) may be of value in young children where distal humeral growth disturbance is suspected.3

 

DIFFERENTIAL DIAGNOSIS

Medial humeral condylar or trochlear growth disturbance Malunited lateral humeral condyle fracture

Congenital dislocation of the radial head

Malunited fracture/separation of the distal humeral physis

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FIG 1 • A,B. AP and lateral radiographs obtained preoperatively for a patient with cubitus varus.

 

NONOPERATIVE MANAGEMENT

 

Nonoperative management does not affect the appearance of cubitus varus.

 

If correction is contemplated, surgery should be undertaken at least 1 year after injury to ensure that there is no evidence of distal humeral avascular necrosis.

 

SURGICAL MANAGEMENT

 

Indications

 

 

 

 

Skeletally immature child with posttraumatic cubitus varus Full elbow extension and flexion to at least 130 degrees Child and family unaccepting of the appearance of the elbow

 

 

At least 1 year after initial injury Goals

 

Correction of the carrying angle to equal the contralateral side7

 

In our experience, rotational deformity less than 45 degrees is well compensated for by shoulder and forearm rotation and does not need to be addressed in the osteotomy.

 

Preoperative Planning

 

Preoperative AP radiographs of both elbows should be taken in full extension and supination.

 

 

The angle of Baumann and the humeral-elbow-wrist angle should be determined for both sides.

 

A tracing of the normal arm on tracing paper is reversed and superimposed on the radiograph of the operative arm (FIG 2A-C).

 

By adding the humeral-elbow-wrist angles, the amount of planned correction can be estimated (FIG 2D).5 Alternatively, attempting to match the Baumann angle of the contralateral side can help estimate the amount of correction needed.

 

The distal osteotomy cut is just proximal to the olecranon fossa.

 

The osteotomy is planned with equal lengths of the proximal and distal limbs; this diminishes the tendency for a lateral condylar prominence.5

 

 

 

FIG 2 • Preoperative templating for the osteotomy. A-C. Preoperative assessment using radiographs of the affected and nonaffected sides. A tracing of the nonaffected side is reversed and placed over a radiograph of the affected side to estimate the amount of correction. D. Planning of equal limb lengths for the osteotomy. (continued)

 

 

P.133

 

 

 

FIG 2 • (continued) E. Example of a step cut osteotomy. Shaded areas show bone that will be removed.

 

 

The angle of the wedge to be removed is the same as the angle of desired correction.

 

Because the osteotomy is performed proximal to the deformity apex and hinges medially, there is a lateral shift of the forearm axis that will make the lateral condyle more prominent than in the normal arm, even with equal osteotomy limbs.

 

This appearance is more accentuated in patients with neutral humeral-elbow-wrist angles.

 

In these cases, a complete osteotomy with medial translation of the distal fragment should be planned, or a translation step cut osteotomy can be performed (FIG 2E).

 

Positioning

 

The patient is placed supine with the arm on a radiolucent extremity table. A sterile upper arm tourniquet is used; this facilitates complete intraoperative visualization of the upper arm.

 

TECHNIQUES

• Exposure

The lateral approach to the distal humerus is used between the lateral head of the triceps muscle and the extensor carpi radialis longus muscles (TECH FIG 1A). A posterior approach can be used as well, if cosmetic appearance is of paramount importance; however, the lateral approach is technically simpler.

The distal humerus is subperiosteally exposed both anteriorly and posteriorly, and small Hohmann retractors are placed (TECH FIG 1B).

 

 

 

 

TECH FIG 1 • A. Lateral approach to the elbow between the lateral head of the triceps and the extensor carpi radialis longus. Incision is placed posterior to the epicondylar ridge. B. The incision is carried down to the epicondylar ridge with the triceps posterior and the extensor carpi radialis longus anterior. The dissection is continued subperiosteally both anterior and posterior completely to the medial side. The osteotomy is then performed with an oscillating saw.

 

 

The proximal and distal osteotomy cuts are made with a small oscillating saw as per the preoperative template. Kirschner wires inserted under image intensifier can be used to mark the osteotomy sites.

 

 

The distal osteotomy is performed proximal to the olecranon fossa. The proximal osteotomy meets the distal osteotomy at the medial cortex, leaving it intact.

 

• Osteotomy Closure and Fixation

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  With the elbow extended, a valgus force is placed on the elbow, closing the osteotomy by creating a greenstick fracture at the medial cortex.

   

  A single distal lateral to proximal medial Kirschner wire is placed percutaneously (not through the incision) to hold the osteotomy apposed.

   

  The osteotomy site is tested for stability with real-time fluoroscopy. If the osteotomy is unstable, a second distal medial to proximal lateral Kirschner wire is used to supplement fixation (TECH FIG 2).

   

  If there is a lateral condylar prominence after performing the greenstick osteotomy, the Kirschner wire is removed, the medial cortex is cut, and the distal fragment is translated medially to remove the prominence. In this situation, routine medial and lateral Kirschner wire fixation is used.

   

  The medial Kirschner wire is inserted with the elbow relatively extended.

   

  The thumb is used to hold the ulnar nerve posterior to the medial epicondyle within the cubital tunnel.

   

  A small skin incision is made over the medial epicondyle, and a hemostat is used to spread the subcutaneous tissue to the underlying bone.

   

   

   

  TECH FIG 2 • Fixation with medial and lateral Kirschner wires above the physis.

   

   

  Care is taken to prevent the wires from crossing at the osteotomy site.

   

  Fixation is evaluated with biplanar fluoroscopy to ensure proper pin placement before wound closure.

• Closure

 

The wound is irrigated and closed in layers in the standard fashion.

 

The Kirschner wires are left protruding from the skin and are bent to prevent migration of the pins underneath the skin.

 

A long-arm cast or splint is applied with the elbow in 90 degrees of flexion and the forearm in slight pronation. The patient should be closely monitored in the early postoperative period for swelling.

 

If a splint is used, it is converted to a long-arm cast after swelling has subsided.

 

PEARLS AND PITFALLS

Patient

selection

• Parents and patients should understand the goal of the surgery, which is to

improve the appearance of the elbow.

Diagnosis

• Patients with other conditions, such as growth disturbance of the distal

  humerus, should be identified preoperatively.

• These patients often have a progressive deformity and are better treated at skeletal maturity using other fixation methods.

Preoperative

• Before operating, the surgeon must know the normal humeral-elbow-wrist

angle for each particular patient as well as the amount of deformity.

 

 

	planning     Performing ▪ Subperiosteal exposure in the distal humerus is essential. the osteotomy ▪ An intact medial cortex greatly enhances osteotomy stability.     Lateral ▪ The osteotomy should be assessed with the elbow extended after closing the condylar osteotomy. prominence ▪ Patients with a neutral contralateral carrying angle should have complete osteotomy with translation of the distal fragment.     Fixation ▪ Stability of fixation should be tested intraoperatively with fluoroscopy, and problems additional fixation is added as necessary.

 

 

 

P.135

 

 

 

 

FIG 3 • A,B. Postoperative AP and lateral radiographs.

POSTOPERATIVE CARE

 

With the technique described, patients are immobilized in a long-arm cast for 4 to 6 weeks. When radiographs show callus formation at the osteotomy site, the percutaneous Kirschner wires can be removed (FIG 3).

 

The patient is then given a sling, and active range-of-motion exercises are initiated.

 

Once radiographic union is achieved, the sling is discontinued, and the patient can begin full activities once range of motion is restored.

 

OUTCOMES

Patient outcomes after supracondylar humeral osteotomy are good to excellent in most cases, with retention of range of motion and improved appearance of the elbow as the major outcome measures.

Loss of fixation, persistent lateral condyle prominence or undercorrection, and hypertrophic scar negatively impact outcome.6

 

 

COMPLICATIONS

Persistent lateral condylar prominence6 Nonunion

Refracture6

Hypertrophic lateral scar6

Loss of fixation2 Recurrent deformity

Radial or ulnar nerve palsy Infection

 

 

REFERENCES

1. Davids JR, Maguire MF, Mubarak SJ, et al. Lateral condylar fracture of the humerus following posttraumatic cubitus varus. J Pediatr Orthop 1994;14:466-470.

    

    

2. Hernandez MA III, Roach JW. Corrective osteotomy for cubitus varus deformity. J Pediatr Orthop 1994;14:487-491.

    

    

3. Ippolito E, Moneta MR, D'Arrigo C. Post-traumatic cubitus varus. Long-term follow-up of corrective supracondylar humeral osteotomy in children. J Bone Joint Surg Am 1990;72(5):757-765.

    

    

4. Labelle H, Bunnell WP, Duhaime M, et al. Cubitus varus deformity following supracondylar fractures of the humerus in children. J Pediatr Orthop 1982;2:539-546.

    

    

5. Oppenheim WL, Clader TJ, Smith C, et al. Supracondylar humeral osteotomy for traumatic childhood

   cubitus varus deformity. Clin Orthop Relat Res 1984;(188):34-39.

    

    

6. Voss FR, Kasser JR, Trepman E, et al. Uniplanar supracondylar humeral osteotomy with preset Kirschner wires for posttraumatic cubitus varus. J Pediatr Orthop 1994;14:471-478.

    

    

7. Wong HK, Balasubramanian P. Humeral torsional deformity after supracondylar osteotomy for cubitus varus: its influence on the postosteotomy carrying angle. J Pediatr Orthop 1992;12:490-493.