Each bone of the shoulder girdle (Fig. 34-1)—the proximal humerus, the scapula, and the clavicle—can give rise to a primary bone tumor or be involved by an adjacent soft tissue sarcoma.¹ The proximal (upper) humerus is one of the most common sites for high-grade malignant bony tumors in both adults and children, and it is the third most common site for osteosarcomas. Chondrosarcomas also commonly involve the shoulder girdle, often arising from the scapula or the proximal humerus. The bones of the shoulder girdle may also be involved secondarily by high-grade soft tissue sarcomas or metastatic tumors that often require resections similar to those used in the treatment of high-grade primary bony sarcomas. Metastatic tumors often involve the shoulder girdle, and because of the extent of bony destruction and the presence of large extraosseous components, the treatment is sometimes similar to that for primary malignant bony sarcomas. For example, hypernephromas (renal cell carcinomas) have a unique propensity to involve the proximal humerus, often as a solitary metastasis. They commonly result in extensive bony destruction with a large soft tissue component.

The surgical treatment of a malignant bony tumor involving the shoulder girdle consists of three stages: (a) wide surgical resection of the tumor, (b) reconstruction of the skeletal defect, and (c) multiple muscle transfers to provide soft tissue coverage, stabilize the shoulder girdle, and restore function to the upper extremity.

The aim is to provide a stable shoulder and preserve a functional elbow and hand. Each of the various surgical techniques currently in use for reconstruction of a segmental defect of the humerus or shoulder girdle offers some degree of stability, function, durability, range of motion (ROM), and preservation of motor power.

Malawer et al. have developed a six-stage surgical classification system.3 This system is based on current concepts of surgical margins, the relationship of the tumor to anatomic compartments (i.e., intracompartmental vs. extracompartmental), the status of the glenohumeral joint (intra-articular vs. extra-articular), the magnitude of the individual surgical procedures, and the presence or absence of the abductor mechanism (deltoid muscle, rotator cuff muscle, or both).

The six-stage classification is as follows (Fig. 34-2):

Each of the six types is further modified according to a major variable: the presence or absence of the main motor group, the abductor mechanism (i.e., deltoid and rotator cuff muscles). The abductors are either present (subtype A) or partially or completely resected (subtype B). The abductor mechanism is almost always resected when there is extraosseous extension of a bone tumor in this area. The loss of any component of the
abductor mechanism tends to create a similar functional disability. Regardless of histology or primary bone involvement, subtype A generally entails an intracompartmental resection and subtype B an extracompartmental resection (Table 34-1).

Sarcomas, which arise from mesenchymal tissues (mesodermal embryonic layer), grow in a centripetal manner and form ball-like masses and compress the surrounding muscle into a pseudocapsule layer. Sarcomas typically respect fascial borders and generally grow along the path of least resistance. This growth pattern is in contrast to that of carcinomas, which are invasive and usually penetrate compartmental borders. The pseudocapsule layer contains microscopic, finger-like projections of tumor referred to as satellite nodules. Sarcomas spread locally along the path of least resistance. Surrounding fascial layers resist tumor penetration and provide boundaries to local sarcoma growth. These boundaries form a compartment around the tumor. A sarcoma will grow to fill the compartment in which it arises; only rarely does a sarcoma extend beyond its compartmental boundaries. With reference to bony sarcomas that extend beyond the cortices into the surrounding soft tissues, the term “functional anatomic compartment” refers to the investing muscles that are compressed into a pseudocapsular layer. These muscles provide the fascial borders of the compartment, which has important surgical implications. A wide resection (i.e., compartmental resection) of a bone sarcoma entails removal of the entire tumor and pseudocapsular layer and must therefore encompass the investing normal muscle layers.

The functional compartment surrounding the proximal humerus consists of the deltoid, subscapularis, and remaining rotator cuff musculature, latissimus dorsi, brachialis, and portions of the triceps (Fig. 34-4).

High-grade sarcomas that extend beyond the bony cortices of the proximal humerus involve and compress the investing muscles that form the compartmental borders

and pseudocapsular layer. They grow along the path of least resistance and therefore are directed toward the glenoid and scapular neck by the rotator cuff and the glenohumeral joint capsule. Anteriorly, the tumor is covered by the subscapularis, which bulges into and displaces the neurovascular bundle (axillary vessels and brachial plexus). Only rarely does a proximal humerus sarcoma extend beyond the compartmental borders. In these instances, the tumor usually protrudes through the rotator interval. A wide resection for a high-grade sarcoma must therefore include the surrounding muscles that form the pseudocapsular layer, the axillary nerve, the humeral circumflex vessels, and the glenoid (extra-articular resection).

Most high-grade scapular sarcomas arise from the region of the scapular neck and body. The compartment consists of all of the muscles that originate on the anterior and posterior surfaces of the scapula. In most cases, the deltoid is protected by the rotator cuff muscles. Because the anatomic origin of most tumors is in the neck, the rotator cuff muscles are compressed into a pseudocapsular layer by sarcomas that arise from the scapula. The subscapularis also protects the neurovascular bundle from tumor involvement. The head of the proximal humerus is contained within the compartment surrounding the scapula. The tumor follows the path of least resistance and typically crosses the glenohumeral joint, grossly or microscopically, to involve the humeral head. Direct tumor extension through joints or articular cartilage is rare and typically occurs as the result of a pathologic fracture. Because of the small size of the glenohumeral joint, the tumor almost always involves the capsule or the synovium. The long head of the biceps tendon, which is intra-articular, is another pathway by which the tumor may cross the joint. Wide resection of a high-grade scapula sarcoma must therefore include the rotator cuff and, in most instances, the humeral head.

The shoulder joint appears to be more prone than other joints to intra-articular or pericapsular involvement by high-grade bone sarcomas. Figure 34-5 show the mechanisms of tumor
spread. Direct capsular extension, direct tumor tracking along the long head of the biceps, a poorly planned biopsy, and pathologic fracture are mechanisms of glenohumeral contamination and make intra-articular resection for high-grade sarcomas a higher risk than extra-articular resection for local recurrence. A local recurrence in this region often requires a forequarter amputation and may compromise patient survival. (This is in contrast to most clinical experience with resections of the distal femur, which tend to be intra-articular.) Therefore, extra-articular resection is recommended for most high-grade sarcomas of the proximal humerus and scapula (Fig. 34-6A,B).

Appropriate imaging studies are crucial to successful resection of tumors of the shoulder girdle (Fig. 34-7). The most useful preoperative evaluations are computed tomography (CT), 3D-CT (Fig. 34-8), magnetic resonance imaging (MRI), arteriography, and three-phase bone scans. For large tumors of the proximal humerus, a venogram may be warranted if there is clinical evidence of distal obstruction.

A unique method developed for the postoperative management of pain in patients undergoing major tumor surgery is the use of perineural catheters. This technique involves the direct placement of a silastic (epidural type) catheter within the nerve sheath of the brachial plexus prior to closure of the wound (Fig. 34-16). Twenty milliliters of 0.25% of Marcaine is perfused initially, and then a continuous infusion of 2 to 4 mL/hour of 0.025% for the immediate postoperative period is given. This technique reduces the postoperative narcotic requirements by about 90%. This is also a very effective means of controlling phantom limb pain in patients requiring a forequarter amputation.

From a rehabilitation perspective, the outcome of resection is clearly superior to that of a forequarter amputation or shoulder disarticulation. Patients undergoing shoulder-girdle resection retain hand function and good elbow function, but they lose some shoulder function, mainly abduction. Shoulder-girdle resection is less disfiguring than amputation and is associated with only minimal pain and edema. Generally, patients’ acceptance of the outcome of their surgery is good to excellent.

Rehabilitation begins with an orientation program that often features pictures of patients who have undergone the procedure and demonstrations of what one can do postoperatively. Preoperatively, a shoulder mold is fashioned using the involved shoulder, provided its contours are not distorted. The cosmetic shoulder helps preserve the symmetry and appearance of the shoulder contour and can support a bra strap or heavy overcoat.

The patient uses a sling postoperatively, and motion is restricted until the incision is healed. The sutures are removed about 2 weeks after surgery. Edema is controlled with an elasticized glove or elastic stockinette. Active motion of the elbow and hand is initiated to preserve strength and ROM and to help minimize edema.

If the incision heals per primam, assistive elbow motion is started within the confines of the sling as soon as the suction catheters have been removed. At about 2 weeks, the sling is removed for passive shoulder ROM and pronation and supination of the wrist. The patient should continue to use the sling intermittently after the incision is healed, primarily for upright activities in which arm support increases comfort. Once the arm is out of the sling, full ROM of elbow (flexion, extension, pronation, and supination) is performed. Passive ROM to the shoulder (flexion, abduction, and external and internal rotation and pendulum exercise) with the help of a family member or physical therapist is recommended.

Rehabilitation depends on the type of reconstructive technique. In general, patients with endoprosthetic intra-articular allografts or composite allograft reconstruction undergo the same rehabilitation program. Those treated by arthrodesis, allograft, or autograft are immobilized for 4 to 5 weeks to allow early bony union to take place.

Despite the complexity of these cases, limb-sparing surgery for both high- and low-grade sarcomas of the proximal humerus is possible in approximately 95% of the cases. Forequarter amputation is indicated mainly for large, fungating tumors, tumors with secondary infections, cases in which there is chest wall involvement, and patients who have had a failed attempt at limb-sparing resection. Preoperative neoadjuvant chemotherapy may allow fracture healing if there is significant tumor necrosis.

Most low-grade sarcomas of the proximal humerus can be treated by type I excision with minimal functional deficit. High-grade sarcomas require a modified Tikhoff-Linberg resection (type V) (see Fig. 34-3). Intra-articular and synovial involvement is more common with high-grade chondrosarcomas and with osteosarcomas of the shoulder girdle than with such tumors at other anatomic sites. Thus, extra-articular, rather than intra-articular, resections are recommended for high-grade tumors of the proximal humerus. Prosthesis, allograft, or allograft prosthetic composite can be used for reconstruction following a marginal resection (type I) for a low-grade lesion. Arthrodesis is rarely performed today. Following resection of a high-grade lesion (stage IIB), the aim is to provide a stable shoulder that will preserve function in the elbow and hand. Regardless of the type of reconstruction planned, the magnitude of the surgical resection depends on the grade of the tumor and its anatomic extent.

A major consideration in the preoperative evaluation and surgical planning is the intraosseous extension of the tumor within the bone marrow. The humerus is shorter than the femur and tibia, the two most common sites of sarcomas, and large tumors of the humerus often require resection of a significantly larger portion of the bone. It is not unusual to resect 50% to 80% of the humerus. Tumors arising within the diaphysis may require a total humeral resection and replacement of the glenohumeral and elbow joints. The surgeon must have various lengths and diameters of intramedullary stems at hand. The final decision about the extent of resection needed is made at the time of surgery.

The abductor mechanism (i.e., the deltoid muscle and the rotator cuff) normally covers the shoulder joint. These structures are usually resected in patients with high-grade proximal humeral sarcomas. Following the resection, joint coverage and stability are essential to eliminate dead space, decrease the risk of infection, and maintain good elbow and hand function. The key muscle transfers in the reconstruction are the pectoralis major, the biceps, and the latissimus dorsi; these must be identified and preserved during the resection.