Synthes Spiral Blade Intramedullary Nail System for Proximal Humeral Fractures

SYNTHES SPIRAL BLADE
INTRAMEDULLARY NAIL
SYSTEM FOR PROXIMAL HUMERAL
FRACTURES

Jeffrey M. Conrad, Michael S. Wildstein, and Langdon A. Hartsock

Osteoporosis is a significant health care problem facing American men and women. It is estimated to be responsible for 1.5 million fractures each year. Up to 50% of women over the age of 50 years and 33% of men over the age of 70 years will have a fracture secondary to osteoporosis.1 Rose et al² investigated the incidence and other epidemiological aspects of humeral fractures in an American community. They reported an incidence of 105 fractures per 100,000 person-years for the population of Rochester, Minnesota; furthermore, 76% occurred in post-menopausal women. Treatment of proximal humerus fractures is no easy task. One must consider the fracture classification, bone quality, age of the patient, and activity level to determine the best treatment plan. The poor quality of bone in osteoporotic patients presents the surgeon with difficult decisions for treatment. Most of these fractures can be treated nonoperatively; however, internal fixation is required in those patients with displaced or comminuted fragments, instability of the glenohumeral joint, or neurovascular injury. Other possible indications for operative intervention depend not only on the fracture personality, but also on the patient’s age, other associated injuries, preinjury activity level, and occupational demands.³

ANATOMY

The proximal humerus can be divided into four segments: humeral head, greater tuberosity, lesser tuberosity, and the humeral shaft. The anatomic neck is located at the junction between the tuberosities and the humeral head, and the surgical neck is found between the tuberosities and the humeral shaft.⁴ The main blood supply to the humeral head is via the ascending branch of the anterior humeral circumflex and its intraosseous continuation, the arcuate artery. Inserting onto the tuberosities are the four tendons forming the rotator cuff muscles. The supraspinatus, infraspinatus, and teres minor all insert on the greater tuberosity, while the subscapularis inserts onto the lesser tuberosity.⁵

The most widely used classification for proximal humerus fractures is the Neer Classification. Neer⁴ used radiographic appearance of proximal humerus fragments, specifically the four major anatomic segments, to classify the fracture type (two-, three-, or four-part). He also noted that a fracture was considered minimally displaced (regardless of level or number of fracture lines within the humerus) as long as no segment is displaced more than 1 cm or angulated more than 45 degrees. The universal acceptance of this classification can be attributed to its ability to describe the fracture pattern, determine treatment, and predict prognosis.

EXISTING METHODS OF INTERNAL FIXATION

There are many options for internal fixation: percutaneous screw or pin fixation,^6,7 tension band,^7,8 intramedullary fixation^9–11 (with or without tension band^7,12), buttress plate,^7,13 90-degree condylar plate,¹⁴ or hemiarthroplasty.^12,13 The ultimate goal of treatment is full function without pain. There are also significant complications with fixation of proximal humerus fractures. Interruption of the blood supply to the humeral head can lead to avascular necrosis. Nonunion is also a significant problem especially in the two- and three-part fractures. This can be due to soft tissue interposition, excessive soft tissue/periosteal stripping, or poor fixation. In addition, with the use of buttress plates in the elderly patient, there is a significant chance of screw cutout due to the poor quality of bone in the proximal humerus.^8,9,13

Closed reduction and percutaneous pinning is indicated in two-part surgical neck fractures with minimal comminution, minimal displacement, and good bone quality.7 This form of treatment is appealing as it is less invasive and avoids compromising the blood supply to the head of the humerus.⁵ Usually the head is abducted or in neutral position and the shaft is displaced medially due to the pull of the pectoralis major. Although closed reduction and percutaneous pin fixation of three-part fractures have been reported, the fixation is challenging and not as stable as other forms of treatment.^7,13

Open reduction and internal fixation is necessary for those fractures that cannot be adequately reduced by closed methods. The use of plates and screws can obtain good results in younger patients; however, in elderly patients with osteoporosis the screw purchase can be less than optimal. The use of buttress plates has fallen out of favor due to the extensive soft tissue exposure necessary for adequate reduction, placing the blood supply at risk.^5,13 In addition, there is a risk of secondary impingement when the hardware is placed too high.¹³

Hawkins et al⁸ reported a retrospective review of 15 patients who sustained three-part fractures of the proximal humerus. Fourteen of fifteen patients were treated with a tension band wiring technique. The other patient was treated with a buttress plate. It was recommended that buttress plating not be used in older osteoporotic patients. Tension banding allows incorporation of the healthy rotator cuff tissue in the fixation, and in this study there were no reports of fixation failure in those treated with the tension band.

The use of intramedullary devices in the treatment of proximal humerus fractures has distinct advantages over other forms of treatment. The use of a limited approach allows for the preservation of the soft tissues, which means that the blood supply is not disturbed. In addition, with stable fixation there is an advantage of early range of motion and mobilization. This allows for preservation of the strength of the rotator cuff and other supporting muscles. Finally, the intramedullary nail is a load-sharing device, which allows for appropriate bone remodeling and early callus formation.¹¹

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