Download Distal Humeral Osteotomy

11
Distal Humeral
Osteotomy
Thomas Duquin and Scott P. Steinmann
INTRODUCTION
Osteotomy of the distal humerus is a relatively uncommon and technically demanding procedure.
Elbow anatomy and function are a complex interaction of the ulnohumeral, radiocapitellar, and
proximal radioulnar joints. A clear understanding of the bony and soft tissue anatomy, as well as
elbow kinematics, is necessary for a successful outcome following distal humeral osteotomy. This
knowledge must include both normal elbow anatomy as well as the patient’s pathology.
Elbow functional range of motion is a 100-degree arc of motion between 30 degrees of extension
and 130 degrees of flexion. The normal carrying angle of the elbow is between 7 and 14 degrees
of valgus, with females having slightly higher valgus angles than males. The epicondylar axis is
parallel to the articular surface in the coronal plane, and the distal humeral articular surface has a
30-degree anterior angulation in the sagittal plane. The epicondylar axis of the distal humerus is
3 degrees internally rotated in relation to the articular surface. Stability of the elbow joint is a complex interaction of bony, ligamentous, and muscular stabilizing forces. The primary stabilizers of the
joint are the ulnohumeral articulation, the lateral ulnar collateral ligament, and the anterior band of
the medial collateral ligament. Secondary stabilizers of the elbow include the radiocapitellar articulation as well as the tendon origins of the flexor and extensor muscles of the forearm.
Distal humeral deformities are often the result of malunited fractures in children and adults. In
children, the deformity can often be well tolerated for several years. However, the abnormal alignment of the elbow results in growth disturbances, remodeling and wear of the remainder of the
elbow joint that over time can lead to ligamentous insufficiency, and nerve dysfunction and degenerative changes in the elbow joint. The most common deformities are varus and extension of the
distal humerus as a result of malunited supracondylar humerus fractures. Cubitus varus results in
an abnormal vector of the triceps tendon that ultimately worsens the deformity and causes attenuation of the lateral ulnar collateral ligament leading to tardy posterolateral rotatory instability of the
elbow.
INDICATIONS/CONTRAINDICATIONS
Patients with distal humeral malunions can present with a myriad of complaints. Typically these fall
into three categories: the first is the patient who develops degenerative changes in the joint resulting
in contractures and pain; while the second group develops instability and complains of progressive deformity and mechanical symptoms, the third group develops nerve-related symptoms as a
result of the deformity. Symptomatic deformity of the distal humerus is the primary indication for
an osteotomy, with the goal to restore alignment and joint biomechanics. In the face of instability,
osteotomy to realign the joint forces is essential for success of the ligament reconstruction.
Clinical evaluation of the elbow alignment should be performed with the forearm supinated
in and in full extension. The angle between the humeral shaft and ulnar shaft can be measured to
determine the carrying angle of the humerus (Fig. 11-1). Care must be taken to avoid internal or
external rotation of the shoulder as this can exacerbate or lessen the actual deformity, especially if a
flexion contracture exists. Accurate assessment of range of motion, bony impingement, and stability of the elbow is essential. Signs of instability include catching or clicking with range of motion
from flexion to extension as well as a positive posterolateral rotary drawer or pivot shift maneuver.
Fluoroscopic evaluation allows for a dynamic examination of the elbow and aids in the assessment
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PART II Fractures and Trauma
FIGURE 11-1
Clinical photograph of a patient with
varus deformity of the distal humerus.
Examination with the arm supination allows
for accurate assessment of the deformity.
of joint stability. Careful neurologic examination is important to assess for compression of the ulnar
nerve in the cubital tunnel as a result of the deformity, instability, or a snapping medial triceps.
Computer tomography (CT) scan with three-dimensional (3D) reconstruction can be helpful in
characterization of the deformity as most malunions have deformity in more than one plane. Newer
computer software can also be used as part of the preoperative planning to determine the exact location and orientation of the osteotomy cuts to allow for appropriate realignment of the distal humerus.
Advances in 3D printing methods now allow for the creation of plastic models that can be very helpful
in understanding the deformity and planning the corrective osteotomy.
The primary indications for a distal humeral osteotomy are pain relief and to restoration of function
associated with a malunion of the distal humerus. Typically, a symptomatic varus deformity greater
than 15 degrees is an indication for distal humeral osteotomy. In the case of instability, the alignment
of the distal humerus should be corrected at the time of ligament reconstruction.
Contraindications for distal humeral osteotomy include the presence of infection, patient noncompliance, or unrealistic expectations. Caution should be advised in patients who actively use
tobacco or who have impaired healing ability due to underlying medical conditions or poor nutrition. The use of prophylactic osteotomy in the asymptomatic patient with significant deformity is
debatable, and careful patient selection should be advised prior to proceeding with the procedure.
The presence of degenerative changes in the elbow joint may be an indication for total elbow arthroplasty instead of corrective osteotomy. There is little information as to the degree of arthritic change
that can be accepted in the osteotomy patient. Alterative treatment options for patients with minor
deformity–associated degenerative changes and contracture include a debridement procedure with
capsular release and recontouring ostectomy of the distal humerus to improve range of motion. In
the face of instability associated with deformity in the elderly, low-demand patient-isolated ligament
reconstruction may provide stability with less morbidity than an osteotomy. If the patient’s symptoms are isolated to the ulnar nerve, decompression or transposition of the nerve may be all that is
needed. Careful preoperative evaluation is needed to assess which aspects of the patient’s pathology
are actually symptomatic.
PREOPERATIVE PREPARATION
The development of a clear understanding of the patient’s deformities and anatomy is essential for a
successful osteotomy. Full-length radiographs of bilateral upper extremities are useful for determining the degree of varus angulation of the humerus. The alignment or carrying angle of the arm can
be assessed radiographically by determining the angle between the long axis of the humerus and
the ulna (Fig. 11-2). The contralateral extremity alignment is helpful as a template for the desired
degree of correction. The lateral radiograph can be examined for extension or flexion malunions by
using drawing the anterior cortical line that should bisect the capitellum on the lateral radiograph.
A CT scan with 3D reconstruction is extremely valuable in understanding the degree and location
of the deformity, especially with regard to rotational deformities of the distal humerus (Fig. 11-3A
and B). We routinely obtain a CT scan prior to the surgery, and newer computer software allows for
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templating of the proposed osteotomy, which is easier than the traditional paper cutouts that were
used historically. In difficult cases with extreme deformities, a 3D model of the humerus can be
obtained to allow for actual preoperative performance of the osteotomy on the model.
FIGURE 11-2
Bone length radiograph of the left upper extremity demonstrating the
measurement of the varus deformity of 21 degrees.
FIGURE 11-3
Three-dimensional CT scan images of distal humeral fracture malunion. A: AP view demonstrating varus deformity. B: Lateral view
demonstrating extension deformity.
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FIGURE 11-4
Technique for templating distal humeral osteotomy. A: A line is drawn perpendicular to humeral shaft. B: A second line is drawn with the desired
degree of correction and moved to 5 mm proximal to the olecranon fossa. C: The line perpendicular to the humeral shaft is moved distally until it
contacts the second line. D: The third line is drawn from the point where the perpendicular line intersects the lateral humeral cortex to a point that
is equal to the width of the humeral shaft along the distal line. This completes the template for the closing wedge osteotomy.
Templating starts with drawing a line that is perpendicular to the long axis of the humeral shaft (A).
A second line is drawn at an angle equal to the desired degree of correction (B). This line is positioned 5
mm above the superior aspect of the olecranon fossa. The line perpendicular to the shaft is then moved
distally to intersect the second line along the medial cortex. The third line is drawn from the point where
the line perpendicular to the shaft intersects the lateral cortex to a point on the second line that is equal
to the width of the humeral shaft at the level of the perpendicular line (C). This creates the triangle of
bone that is to be removed as a part of the closing wedge osteotomy (Fig. 11-4A–D). The exact location
of the cuts can be measured in relation to known landmarks such as the medial and lateral epicondyles,
which will help at the time of the surgery. The degree of correction in the sagittal plane can be assessed
using a lateral radiograph or lateral view on the 3D CT Scan. The angle of desired correction is made
through the proximal cut that is perpendicular to the axis of the humeral shaft on the coronal plane.
SURGICAL TECHNIQUE
The patient is positioned supine on the operating room table with the table tilted away from the surgical extremity to allow the arm to be positioned over the chest (Fig. 11-5). The arm can be brought
out over the edge of the table for fluoroscopic imaging during the procedure. A sterile tourniquet is
positioned on the upper arm. The arm should be examined under anesthesia using fluoroscopic imaging to assess for ligamentous instability. Close attention to the competence of the lateral ulnar collateral ligament is important and can be assessed using a pivot shift test or posterolateral drawer test.
The exposure of the distal humerus involves full exposure of the medial and lateral columns as well
as the anterior and posterior cortices to allow for protection of the neurologic and vascular structures
of the arm. This can be performed using a triceps on approach via a single posterior incision or a
medial and lateral incision technique. Our preference is to use a two-incision technique that eliminates
the need for raising large skin flaps and decreases the risk of wound-healing problems or seromas.
The medial incision is made along the medial column and starts 2 cm distal to the joint and
extends 6 cm proximal to the joint. The ulnar nerve is identified proximally at the medial border
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11 Distal Humeral Osteotomy
of the triceps tendon. The nerve is mobilized through the cubital tunnel, including the fascia of the
flexor carpi ulnaris. The nerve is mobilized anteriorly with care to coagulate the venous plexus along
the posterior cortex of the distal humerus using bipolar cautery. The medial intermuscular septum is
released from the medial epicondyle and excised to expose the medial column of the distal humerus.
A Cobb elevator is then used to mobilize the triceps muscle from the posterior cortex of the distal
humerus. The capsule of the elbow joint can be left intact. The brachialis muscle is released from the
anterior cortex of the distal humerus with care to remember that the humerus has a triangular shape
distally with an anterior angulation (Fig. 11-6).
The lateral exposure starts just distal to the lateral epicondyle and extends 6 cm proximally along
the lateral column of the humerus. The interval between the triceps tendon and the brachioradialis is incised to expose the lateral column of the humerus. The triceps tendon is mobilized, and
the posterolateral aspect of the distal humerus is exposed and connected to the medial incision.
The brachioradialis and the brachialis muscles are mobilized from the anterior aspect of the distal
humerus with care to stay subperiosteal to prevent injury to the radial nerve that is found between
the brachialis and brachioradialis muscles. The radial nerve pierces the lateral intermuscular septum
and crosses from the posterior compartment to the anterior compartment approximately 10 to 12 cm
above the lateral epicondyle (Fig. 11-7).
Once the exposure is completed, the osteotomy cuts can be planned. The desired angle of correction is identified based on the preoperative templating, and care should be taken to account for
flexion–extension or rotational malunions, which should be corrected at the time of the osteotomy.
Using fluoroscopic imaging, a Steinmann pin is placed perpendicular to the long axis of the humerus.
A goniometer is then used to place a second pin at the desired angle of correction 5 mm above the
superior aspect of the olecranon fossa. Pin placement can be confirmed using fluoroscopic imaging
to ensure the correct angle of correction (Fig. 11-8A–C).
FIGURE 11-5
Operating room setup for procedure
with a patient positioned supine
and arm positioned across the chest
allowing for easy access to medial and
lateral incisions.
FIGURE 11-6
Medial column exposure with ulnar nerve
moved anteriorly (yellow vessel loop).
Brachialis muscle is released anteriorly
and triceps posteriorly to expose the
distal humeral osteotomy site.
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PART II Fractures and Trauma
FIGURE 11-7
Lateral column exposure showing
elevation of brachioradialis and brachialis
anteriorly and triceps posteriorly.
FIGURE 11-8
The use of pins as cutting guides helps facilitate making the correct degree of correction for the osteotomy. A: Intraoperative photograph
demonstrating the use of fluoroscopy and goniometer to plan location of osteotomy cuts. B: Fluoroscopic image showing pin placement
perpendicular to the humeral shaft axis and desired angle of correction. C: Intraoperative photograph demonstrating pin placement to be used
as cutting guide for osteotomy.
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FIGURE 11-9
Osteotomy cuts are made from medial to lateral with care to protect the anterior and posterior soft tissues with retractors. A: Intraoperative
photograph of initial osteotomy cut. B: Fluoroscopic image of firs cut made along guide pin to depth equal to the width of the humerus at the
level of the proximal pin.
The first cut is made along the distal pin that was placed at the desired angle of correction. The cut
is made from medial to lateral just distal to the pin. Care is made to retract the ulnar nerve anteriorly
and to protect the anterior and posterior soft tissues. The cut is made to a depth equal to the width
of the distal humerus, which can be measured prior to making the cut and marked on the saw blade
(Fig. 11-9A and B). The second cut is made parallel to the first pin, which was placed perpendicular
to the axis of the humerus. The saw blade can be angled anteriorly or posteriorly to correct for extension or flexion malunions. The second cut is made completely through the entire distal humerus. The
distal segment can then be translated laterally and a vertical cut is made, completing the triangular
wedge of bone leaving a spike of distal humeral bone. The cut surfaces can then be reduced, and
the lateral spike of bone on the distal fragment overlaps the lateral cortex of the proximal fragment.
A Steinmann pin can be placed through the spike for provisional fixation of the osteotomy laterally
and a second pin placed from the posterior aspect of the medial epicondyle into the lateral aspect of
the proximal humeral shaft. The arm can then be examined clinically and fluoroscopically to confirm that the alignment is in 5 to 10 degrees of valgus. Definitive fixation of the osteotomy is then
performed with medial and lateral plates. The distal fixation is performed first followed by proximal
fixation with compression of the osteotomy site. The elbow is then examined to confirm full range
of motion without impingement or blockage by the hardware. Fluoroscopic imaging is performed
to confirm reduction of the osteotomy site and hardware placement without penetration into the
articular surfaces (Fig. 11-10A and B).
The ulnar nerve is then examined, and if the nerve can be placed back to the anatomic position without impingement or instability with range of motion, it is left in the cubital tunnel. In the
face of nerve impingement or subluxation of the nerve, an anterior subcutaneous transposition is
performed. The tourniquet is released and hemostasis is performed. The use of a drain is recommended to avoid hematoma formation and is typically removed on postoperative day 1. The fascia
is repaired along the medial and lateral columns with care not to tether the triceps tendon. Standard
skin closure is performed, and the arm is placed in a posterior splint in approximately 60 degrees
of flexion.
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FIGURE 11-10
Fluoroscopic images showing fixation of the osteotomy site with improved alignment. A: Anterior–posterior. B: Lateral.
POSTOPERATIVE MANAGEMENT
The patient is kept overnight for observation, and the arm is elevated with neurovascular evaluation every 4 hours. The drain is removed on the morning following the surgery, and the patient is
discharged home in the posterior splint with instructions to contact the office if he or she notices any
numbness, discoloration, or loss of function in the hand and fingers. The patient returns to the office
FIGURE 11-11
Radiographs 8 months following distal humeral osteotomy. A: AP view demonstrating healed osteotomy and correction to 8 degrees of
valgus. B: Lateral radiograph demonstrating correction of the extension malunion. Clinically the patient has no pain and range of motion
from 15 degrees of extension to 130 degrees of flexion and 90 degrees of supination and 80 degrees of pronation.
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at 2 weeks following the surgery, and the splint is removed. The patient is placed into a removable
elbow splint and begins working on gravity-assisted flexion and extension exercises. Six weeks
following the osteotomy, x-ray is obtained to look for early signs of healing. The patient is allowed
to begin active and active-assisted range of motion and is allowed to use the arm for light activities
not lifting anything greater than 1 to 2 lb. A repeat radiograph at 3 months is obtained to confirm
­healing, and the patient is allowed to begin a strengthening program and can progress to full activity
as tolerated by 4 months after the surgery (Fig. 11-11A and B).
SUMMARY
Cubitus varus is most commonly seen following malunited supracondylar distal humerus fractures.
Minor deformities are often cosmetically unappealing but do not result in significant functional deficits. Varus deformity greater than 15 degrees will often lead to functional limitations, ulnar nerve
symptoms, lateral ligamentous laxity, and the development of ulnohumeral arthritis. Patients with
symptomatic cubitus varus without signs of advanced arthritic changes are candidates for a distal
humeral osteotomy.
Distal humeral osteotomy is a technically demanding procedure that requires clear understanding
of the patient’s pathologic anatomy as well as the normal anatomy of the elbow. Preoperative planning with the creating of templates using 3D CT scans helps to allow for successful realignment of
the extremity. Rigid fixation and compression of the osteotomy are best performed using a parallel
plating technique with medial and lateral plates placed with compression of the osteotomy site.
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