Hemiarthroplasty for Proximal Humerus Fractures

Arnaldo I. Rodriguez Santiago, MD

T. Bradley Edwards, MD

Dr. Edwards or an immediate family member has received royalties from Tornier and Orthohelix; is a member of a speakers’ bureau or has made paid presentations on behalf of Tornier; serves as a paid consultant to or is an employee of Kinamed and Tornier; serves as an unpaid consultant to Gulf Coast Surgical Services; has received research or institutional support from Tornier; has received nonincome support (such as equipment or services), commercially derived honoraria, or other non-research-related funding (such as paid travel) from Tornier; and serves as a board member, owner, officer, or committee member of the American Shoulder and Elbow Surgeons. Neither Dr. Rodriguez-Santiago nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter.

PATIENT SELECTION

Hemiarthroplasty is a useful procedure for many acute displaced proximal humerus fractures. Certain fracture patterns preclude the ability to use internal fixation techniques to reconstruct the proximal humerus, particularly in patients with poor bone quality.

HISTORY AND PHYSICAL EXAMINATION

A thorough history is taken from the antecedent trauma responsible for the fracture. Presence of any shoulder problems before the fracture should be noted in the history. Performance of physical examination in a patient with an acute proximal humerus fracture is limited so that the patient is not unnecessarily subjected to pain. A detailed neurovascular examination is performed with specific attention to the sensory and motor functions of the axillary nerve. The sensory function of the axillary nerve can be evaluated by testing sensibility to touch of the posterior aspect of the upper part of the arm (superior lateral brachial cutaneous branch). Motor function may be more difficult to evaluate because pain induced by the fracture may inhibit deltoid contraction. The condition of the soft tissues, particularly anterior at the planned surgical site, is meticulously evaluated.

PREOPERATIVE IMAGING

Three radiographic views are obtained in all patients with a proximal humerus fracture: an AP view of the glenohumeral joint with the arm in neutral rotation, an axillary view, and a scapular outlet view. These radiographs are used to evaluate the fracture pattern (two-part,
three-part, four-part), the amount of displacement of the fracture fragments, the presence of humeral head dislocation, and the presence of a split in the humeral head fragment. AP full-length radiographs of the humerus of both the affected and unaffected extremity, taken with the arm in neutral rotation, are obtained for use in preoperative determination of appropriate humeral head height. These radiographs must include the entire length of the humerus and must be controlled for magnification.

FIGURE 1 AP radiograph shows a four-part humeral fracture-dislocation, a typical indication for hemiarthroplasty.

CT is performed in all patients with substantially displaced proximal humerus fractures. This study allows further elucidation of the fracture pattern and assessment of the amount of displacement of the fracture fragments. Additionally, the position of the tuberosities and the humeral head is visualized, thereby allowing easier identification at the time of surgery.

Placement of the prosthesis at the correct height and version remains one of the most difficult challenges when performing hemiarthroplasty for a fracture. The authors prefer the Gothic arch technique popularized by Krishnan et al.² In preoperative planning for the Gothic arch technique, AP full-length humeral radiographs of the affected and unaffected arm are required. From the radiograph of the unaffected arm, the length of the humerus from the superior aspect of the humeral head to the transepicondylar axis is measured and normalized for magnification (Figure 2, A). This measurement is obtained by first establishing the prosthetic axis proximally within the humeral canal. This is done by measuring the center point of the proximal diaphysis at two locations and connecting these points with a line running the length of the humerus. Next, a line perpendicular to the prosthetic axis is drawn at the superior aspect of the humeral head. A third line is drawn at the transepicondylar axis of the distal humerus. The distance between the superior aspect of the humeral head and the transepicondylar axis is measured in centimeters along the prosthetic axis.

FIGURE 2 Preoperative planning for the Gothic arch technique of determining proper humeral component position. A, From a full-length AP radiograph of the unaffected humerus, the length of the humerus from the superior aspect of the humeral head to the transepicondylar axis is measured and normalized for magnification. B, On the AP radiograph of the affected extremity, a line perpendicular to the prosthetic axis is drawn at the level of the fracture medially. The distance between the medial fracture line and the transepicondylar axis (residual humeral length) is measured. The difference between the humeral length measured on the unaffected radiograph and the residual humeral length measured on the affected radiograph is calculated. C, Photograph shows the marking of this difference on the humeral implant to establish the height at which the humeral stem should be positioned with respect to the medial fracture line. D, AP radiograph demonstrates that the length of the greater tuberosity, when available, is used as a checkrein.

The AP humeral radiograph of the affected extremity is used to establish the prosthetic axis and the transepicondylar axis. A line perpendicular to the prosthetic axis is drawn at the level of the fracture medially. The distance between the medial fracture line and the transepicondylar axis (residual humeral length) is measured and corrected for magnification if necessary. In cases in which the greater tuberosity is visible as a single fragment, the length of the greater tuberosity is measured. The difference between the humeral length measured on the radiograph of the unaffected extremity and the residual humeral length measured on the radiograph of the affected extremity is calculated (Figure 2, B). This difference is marked on the humeral implant to establish the height at which the humeral stem should be positioned with respect to the medial fracture line (Figure 2, C). The length of the greater tuberosity, when available, is used as a checkrein. When the length of the greater tuberosity is added to the length of the residual humerus, the sum
should be approximately 3 to 5 mm less than the humeral length measured on the radiograph of the unaffected humerus (Figure 2, D).

PROCEDURE

Room Setup/Patient Positioning

Proper patient positioning is crucial during shoulder hemiarthroplasty for fracture. We use a standard operating table with the patient positioned sufficiently to the operative side to allow extension of the arm. A rolled sheet is placed between the scapulae to slightly elevate the shoulder off the operating table and allow proper preparation of the posterior aspect of the shoulder. The patient is placed in the modified beach-chair position, with the back of the table elevated approximately 45° to 60° relative to the floor. The position of the patient’s head and neck is checked to ensure neutral alignment. After the head/neck position is deemed acceptable, the forehead and chin are secured. Care should be taken to pad and protect bony prominences and sites of subcutaneous vulnerable nerves near the elbow (ulnar) and knee (peroneal).

Special Instruments/Equipment/Implants

Instruments used during hemiarthroplasty for proximal humerus fractures are listed in Table 1.

Surgical Technique

Surgical Approach and Tuberosity Handling

The area included in the surgical preparation extends medially to the midline, distally to the level of the nipple, and proximally to the level of the mandible and encompasses the entire upper extremity, including the hand. Draping of the patient differs slightly in fracture cases in that the stockinette covers only the forearm so that the elbow and humeral epicondyles are easily accessible to use as reference points in judging prosthetic retroversion.

A standard deltopectoral approach is used for exposure. The skin incision is started at the tip of the coracoid and extends distally and laterally approximately 10 to 15 cm, depending on the size of the patient. A needle-tip electrocautery is used for deep dissection throughout the procedure to minimize blood loss. The interval between the deltoid and the pectoralis major is identified by locating the cephalic vein. If difficulty is encountered in locating the cephalic vein, the deltopectoral interval can be readily detected proximally by identifying a small triangular area devoid of muscle tissue between the proximal portions of the deltoid and pectoralis major muscles. We prefer to retract the cephalic vein laterally with the deltoid because most of the branches of the cephalic vein are based on the deltoid. A self-retaining deltopectoral retractor is placed to maintain exposure during the procedure. The conjoined tendon is identified and traced to its insertion on the coracoid process. The tip of a Hohmann-type retractor is placed behind the base of the coracoid process to provide proximal retraction. With the arm abducted and externally rotated, the apex formed by the insertion of the coracoacromial ligament and the conjoined tendon onto the coracoid process is identified. The conjoined tendon is retracted medially to expose the proximal humerus fracture.

A Cobb elevator is used to perform blunt dissection and begin the process of identification of the tuberosities. In the typical four-part fracture pattern, the lesser tuberosity with the attached subscapularis represents one fragment, the greater tuberosity with the attached posterior superior rotator cuff represents a second fragment, the humeral head represents a third fragment, and the humeral shaft represents the final fragment. A variety of combinations exist; however, the most common fracture pattern for which hemiarthroplasty is indicated involves these major fracture fragments. Control of the lesser tuberosity is achieved by identifying the tuberosity and the subscapularis tendon anteriorly in the shoulder just posterior to the conjoined tendon.

Stay sutures of No. 1 polyester are placed through the subscapularis tendon just medial to its osseous insertion on the lesser tuberosity. One suture is placed superiorly and a second suture inferiorly, if necessary. Sutures are not placed through the lesser tuberosity because it is usually osteopenic and does not support transosseous sutures sufficiently. These sutures will also aid in retracting the lesser tuberosity to gain access to the humeral head fragment.

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