Technique Spotlight: RSA for Fracture

For a patient sustaining a proximal humerus fracture, the goal of treatment is to maximize functional outcome and patient satisfaction. While no clear consensus exists as to the optimal management of these injuries, and the results of closed treatment are frequently adequate in this patient population, certain fracture patterns and patient characteristics may help direct surgeons in selecting an appropriate plan of care. ^,

Current practice suggests reverse total shoulder arthroplasty (rTSA) is best suited in the treatment of elderly patients sustaining proximal humerus fractures with complex fracture patterns who desire the maximum achievable functional result. Specifically, patients suffering from severely displaced three- or four-part fractures or fracture-dislocations, those presenting in a delayed fashion, or individuals found to have poor bone quality are considered optimal candidates for treatment with rTSA. While nonoperative treatment is frequently an option, these fracture patterns are subject to a number of potential complications with nonoperative treatment including malunion, nonunion, and avascular necrosis. ^, Additionally, individuals found to have poor bone quality, including those with osteoporosis, are at increased risk of failure and hardware loosening with open reduction and fixation and should therefore be identified as candidates for rTSA. ^, ^, While hemiarthroplasty may be considered for the rare, unreconstructable younger patients with proximal humerus fracture or patients where a glenoid fracture makes secure baseplate fixation unattainable, rTSA is generally preferred in patients aged 65 and older due to improved postrehabilitation results of forward elevation and functional outcomes. ^, Finally, rTSA is indicated for complex proximal humerus fractures with concomitant irreparable rotator cuff pathology, as the use of the reverse prosthesis alters the center of rotation at the joint such that the arm is reliant on the function of the deltoid muscle rather than a deficient rotator cuff for range of motion. ^,

For patients where the medical comorbidities are severe and the potential benefit of an rTSA over closed treatment only comes with unacceptable anesthetic and surgical risks, closed treatment is preferred. Furthermore, patients must be willing and able to undergo a rehabilitation program postoperatively, have no active infection, have a functioning deltoid/axillary nerve, and a glenoid sufficient for stable glenoid component fixation. Lastly, patients who use the arm as a weight-bearing shoulder, for example, using a walker to assist with ambulation, are relatively contraindicated.

Preoperative Examination

A thorough preoperative history and examination is critical to identify optimal candidates for rTSA following proximal humerus fracture. Elderly female patients are most at risk of proximal humerus fracture. Therefore younger patients presenting with fractures secondary to low-impact trauma necessitate further workup to rule out pathologic causes of injury. Preinjury functional status and hand dominance are also crucial to establishing appropriate expectations of postoperative recovery. Patient medical history including a diagnosis of osteoporosis, anticoagulation use, or other comorbidities will provide insight into infection risk and fitness for surgery. A detailed description of mechanism of injury will offer clues into need for additional workup to identify concurrent trauma to head, neck, shoulder girdle, forearm, or hand.

As with any traumatic injury, physical examination should entail close examination of the affected area and surrounding structures. With a suspected proximal humerus fracture, evaluation of the wrist, forearm, elbow, and shoulder girdle is warranted. Skin examination includes investigation for previous surgical scars, areas of skin tenting, distribution of ecchymosis, and open wounds. Gross deformity may indicate concurrent dislocation of the humeral head. ^, A detailed neurologic examination is crucial, with particular attention focused on the integrity of axillary nerve, as this is the most frequently injured nerve during proximal humerus fracture. ^, For patient comfort, we recommend testing the posterior head of the deltoid by having the patient, with their arm hanging at the side, push the elbow posteriorly against the examiner’s one hand while the examiner’s other hand palpates for firing of the muscle. While motor assessment may be limited by patient intolerance secondary to pain. However, sensory function can be evaluated through light touch. Finally, adequate perfusion should be assessed, and signs of vascular compromise including weak distal pulses, slow capillary refill, and hypoesthesia require immediate attention.

Typical radiographic imaging includes a complete trauma series consisting of true anteroposterior, scapular-Y, and axillary views ( Fig. 29.1 ). ^, Whenever possible, plain radiographic images should be obtained with the patient in the upright position to appreciate the effect of gravity upon the fracture alignment. Computed tomography may be necessary to better evaluate complex fracture patterns and assess the integrity of the rotator cuff musculature. ^, Magnetic resonance imaging (MRI) is rarely indicated. Imaging should be evaluation for alignment, fragmentation of the humeral head or tuberosities, and bone quality as osteoporotic bone is at greater risk of ultimate failure with attempts at reduction with internal fixation. ^, ^, The humerus is the second most common site for long bone metastases, with 8%–10% of lytic lesions progressing to impending or established fracture. Therefore great care must be taken to avoid missing a pathologic fracture secondary to a neoplasm. Furthermore, the presence of an associated glenoid fracture, though rarely described in the literature in limited case reports, may compromise the integrity of reverse baseplate fixation, and thus the glenoid should be carefully scrutinized.

$Fig. 29.1, (A) Anteroposterior and (B) scapula Y views of proximal humerus fracture.$

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