Orif: Humeral Shaft Fracture

The shaft of the humerus extends proximally from the
upper border of the pectoralis major insertion to the supracondylar
ridge distally (Fig. 7-1). The proximal aspect
of the humeral shaft is cylindrical on cross section; distally its
anterior-posterior diameter narrows. The anterior border of the humerus
extends from the anterior aspect of the greater tuberosity to the
coronoid fossa. Its medial border extends from the lesser tuberosity to
the medial supracondylar ridge. Its lateral border extends from the
posterior aspect of the greater tuberosity to the lateral supracondylar
ridge. The deltoid muscle inserts onto the deltoid tuberosity, located
on the anterolateral surface of the proximal humeral shaft. The radial
sulcus contains the radial nerve and the profunda artery. The posterior
surface is the origin for the triceps and contains the spiral groove
(see Fig. 6-1).

The medial and lateral intermuscular septa divide the
arm into anterior and posterior compartments. The biceps brachii,
coracobrachialis, and brachialis muscles are contained in the anterior
compartment. The brachial artery and vein and the median,
musculocutaneous, and ulnar nerves course along the medial border of
the biceps. The posterior compartment contains the triceps brachii
muscle and radial nerve. The lateral intermuscular septum is perforated
by the radial nerve and the deep branch of the brachial artery. The
medial intermuscular septum is perforated by the ulnar nerve, the
superior ulnar collateral artery, and a posterior branch of the
inferior ulnar collateral artery (Fig. 7-2).

There is no universally accepted classification system
for humeral shaft fractures. Classically, humeral shaft fractures have
been classified on the basis of various factors that influence
treatment such as (a) fracture location (proximal, middle, or distal
third of the humeral shaft), and in addition whether the fracture is
proximal to the pectoralis major insertion, distal to the pectoralis
major insertion but proximal to the deltoid insertion, or distal to the
deltoid insertion; (b) direction and character of fracture line
(transverse, oblique, spiral, segmental, or comminuted); (c) associated
soft tissue injury (open or closed fracture); (d) associated
periarticular injury involving the glenohumeral or elbow joints; (e)
associated nerve injury involving either the radial, median, or ulnar
nerves; (f) associated vascular injury involving either the brachial
artery or vein; and (g) intrinsic condition of the bone (normal or
pathologic)

The AO/ASIF classification of humeral shaft fractures is based on fracture comminution (Fig. 7-3).
Type A are simple (noncomminuted), type B have a butterfly fragment,
and type C are comminuted. These fracture types are further divided
according to fracture pattern. This alphanumeric classification is used
by both the AO and Orthopaedic Trauma Associations.

The indications for operative management of humeral shaft fractures are as follows:

A standard radiographic examination of the humerus consists of (Fig. 7-4)
anteroposterior (AP) and lateral radiographs, taken at 90 degrees to
one another. The shoulder and elbow joint should be included in each
view.

The radiographs are obtained by moving the patient
rather than simply rotating the injured extremity. In highly comminuted
or displaced fractures, traction radiographs may allow better fracture
definition. Comparison radiographs of the contralateral humerus are
helpful for preoperative planning. Tomograms and computed tomography
are rarely indicated. In pathologic fractures, additional studies
(technetium bone scan, computed tomography, and magnetic resonance
imaging) may be necessary to delineate the extent of disease before
fracture treatment.

The exact nature of the fracture, with identification of all

major fracture fragments, should be determined before one attempts
definitive surgical intervention. Identification of the individual
fragments is often facilitated with traction radiographs. Radiographs
of the opposite, uninjured extremity serve as a template for
preoperative planning; the individual fracture fragments, chosen
implant, and surgical tactic can be drawn on the intact humeral
template. This requires the surgeon to understand the “personality of
the fracture” and to mentally prepare for the operative procedure.

The basic instruments necessary for open reduction and
internal fixation of a humeral shaft fracture plate and screws include
the following (Fig. 7-5):

The patient is positioned supine with the arm placed either on a hand table or arm board (Fig. 7-6).

For
most fractures, I prefer an anterolateral approach to the humerus. An
incision is made along the lateral border of the biceps, ending just
proximal to the elbow flexion crease (Fig. 7-7). The lateral border of the biceps is identified, and the muscle retracted medially (Fig. 7-8). The interval between the brachialis and brachioradialis is identified proximal to the elbow and the two muscles separated (Fig. 7-9).
The brachioradialis is retracted laterally, and the brachialis and
biceps muscles are retracted medially. The radial nerve lies between
the brachialis and brachioradialis and must be identified (Fig. 7-10).
The radial nerve is traced proximally through the lateral intermuscular
septum and protected throughout the remainder of the procedure (Fig. 7-11).
The periosteum is incised longitudinally at the lateral border of the
brachialis muscle, and the humerus is dissected subperiosteally (Fig. 7-12).
The anterolateral approach can be extended proximally into an anterior
approach to the shoulder and distally to an anterior approach to the
elbow.

The
fracture is exposed, evaluated, débrided of hematoma, and anatomically
reduced. Minimal soft tissue stripping should be performed; butterfly
fragments must not be devitalized. Provisional stabilization is
performed using reduction clamps or Kirschner wires. A 4.5-mm broad
dynamic compression plate is usually selected for midshaft fractures (Fig. 7-13).
In smaller patients, a 4.5-mm narrow dynamic compression plate may be
used. If the fracture pattern permits, the plate should be applied in
compression. Lag screws should be inserted through the plate whenever possible (Fig. 7-14). Eight to ten cortices fixation proximal and distal to the fracture should be obtained (Fig. 7-15). Fixation stability must be assessed before closure (Fig. 7-16).
The need to bone graft is determined by the amount of comminution and
soft tissue stripping. In general, one should have a low threshold for
cancellous bone grafting of these fractures when plates and screws are
used. One should obtain final radiographs once surgery is completed (Fig. 7-17).

A closely monitored rehabilitation program is essential
to achieve maximal functional outcome after both operative and
nonoperative humeral shaft fracture management. Early and vigorous
postsurgical range of motion exercises of the hand and wrist should be
strongly urged. As shoulder pain diminishes, range of motion exercises
for the shoulder and elbow are initiated. As union progresses,
supervised exercises

to
recover upper extremity strength are started. Caution is warranted
relative to management of the elbow; it should not be passively
stretched. Myositis ossificans, which has been reported around the
elbow following humeral shaft fracture, can be prevented by exclusively
using active range of motion exercises.