Minimally Invasive Lateral Approach to the Proximal Humerus

Minimally Invasive Lateral Approach to ‌

the Proximal Humerus

The minimally invasive approach to the proximal humerus provides access to the head, surgical neck and proximal third of the humerus. It utilizes two windows, proximal and distal, on either side of the axillary nerve as it runs transversely on the under surface of the deltoid muscle. The use of the lateral minimally invasive approach is for internal fixation of displaced fractures of the proximal third of the humerus. It is of most use in segmental fractures and those fractures of the proximal humerus that have extension down into the humeral shaft.34,35

Position of the Patient

Place the patient in a supine position with the affected arm at the edge of the table. Elevate the head of the table to reduce venous pressure and operative bleeding (see Fig. 1-35). A sandbag should be placed under the patient’s shoulder. Ensure that adequate intraoperative imaging can be obtained before prepping and draping the patient (see Fig. 1-35).

Landmarks and Incision

Palpate the lateral border of the acromion. Define the lower end of the incision by marking the skin with a transverse line 5 cm below the acromion. This line will be approximately 1 cm above the axillary nerve. Make a 5- to 6-cm longitudinal incision from the tip of the acromion down the lateral aspect of the upper arm (see Fig. 1-36). Make a second 5-cm incision distally in the line of the proximal incision (Fig. 1-41). The position of this second incision will depend on the site of the fracture and the length of the implant to be used. Accurate positioning of the distal incision is best achieved by using the image intensifier.

Figure 1-41 Proximally make a 5- to 6-cm longitudinal incision from the tip of the acromion down the lateral aspect of the upper arm. Distally make an incision in the line of the first incision. The length and position of the distal incision will depend on the pathology to be treated and the implant to be used.

Internervous Plane

There is no internervous plane. The lateral approach involves splitting the deltoid muscle.

Superficial Surgical Dissection

Deepen the proximal window in the line of the skin incision to approach the lateral aspect of the deltoid muscle (Fig. 1-42). Carefully split the muscle fibers of the deltoid, but do not extend this split more than 5 cm distal to the acromion. Deepen the distal incision through subcutaneous tissue to expose the lateral aspect of the deltoid muscle (Fig. 1-43).

Deep Surgical Dissection

Through the proximal window, carefully develop an epiperiosteal plane on the lateral surface of the humerus. Using your finger, carefully palpate the axillary nerve, running on the under surface of the deltoid (Fig. 1-44).

Having successfully identified the position of the axillary nerve, split the deltoid in the line of its fibers through the distal incision.

Figure 1-42 Deepen the incisions through subcutaneous tissue to expose the fascia covering the deltoid muscle.

Carefully connect the proximal and distal exposures of the bone by gently developing an epiperiosteal plane using your finger and subsequently the implant (Fig. 1-45).

Dang

The axillary nerve runs on the under surface of the deltoid. As long as one works beneath the deltoid on the bone, the nerve will not be injured. Take care, however, not to aggressively retract the deltoid muscle fibers, either proximally or distally, as this may induce a traction lesion of the nerve.

Figure 1-43 Proximally split the muscle fibers of the deltoid to expose the periosteum overlying the lateral aspect of the proximal humerus. Do not extend this split more than 5 cm distal to the acromion. Distally split the fibers of the deltoid.

Figure 1-44 Palpate the axillary nerve as it runs along the undersurface of the deltoid muscle and develop an epiperiosteal plane on the lateral aspect of the humerus, using blunt dissection.

How to Enlarge the Approach

The proximal incision can be extended proximally, but cannot be extended distally (see page 31, Fig. 1-37). The distal incision can be extended distally to expose the middle third of the humerus by stripping some of the insertion of the deltoid to the lateral aspect of the humerus. The distal window cannot be extended proximally through the substance of deltoid, because this will inevitably damage the axillary nerve.