Although most proximal humerus fractures can be treated nonoperatively, 4-part fractures and 3-part fractures/dislocations in elderly patients often require management with prosthetic arthroplasty. Reverse arthroplasty is gaining in popularity, but hemiarthroplasty still has a role in the management of 4-part and some 3-part fractures and dislocations. The 2 most important technical factors influencing functional outcome in hemiarthroplasty patients are the restoration of the patient’s correct humeral head height and version, and healing of the greater and lesser tuberosities in an anatomic position. Hemiarthroplasty for proximal humerus fracture provides predictable pain relief, but functional recovery is much less predictable.
Key points
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The majority of proximal humerus fractures can be managed non operatively.
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Four part fractures and 3 part fracture/dislocations in elderly patients often require management with prosthetic arthroplasty.
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While reverse shoulder arthroplasty is gaining popularity for the management of fractures in patients over the age of 70, hemiarthroplasty remains a valuable tool in the management of these fractures.
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Restoration of the patients’ correct humeral head height and version and healing of the greater and lesser tuberosities in an anatomic position are crucial for regaining function after this procedure.
Introduction
Proximal humerus fractures represent 4% to 5% of all fractures and 50% of all humerus fractures, increase in incidence with age, are more common in females, and are a leading cause of visits to the emergency room or admission to the hospital. According to Neer, 80% of all proximal humerus fractures are nondisplaced and can be managed nonoperatively. However, recent data from a regional trauma center indicates that the incidence of displaced fractures may be higher than originally described by Neer. In his original description, Neer classified displaced fractures as 2-, 3-, and 4-part fractures or fracture dislocations, as discussed in more detail herein. Hemiarthroplasty was indicated for most 4-part fractures and fracture dislocations as well as selected 3-part fractures and fracture dislocations. As techniques for internal fixation have improved, many 3-part and 4-part fractures in young active patients are currently being treated with osteosynthesis rather than arthroplasty. Moreover, inconsistent results from hemiarthroplasty, particularly in patients older than 70 years, has led to the increased use of reverse total shoulder arthroplasty.
Hemiarthroplasty is still a viable alternative in many patients with proximal humerus fractures. As has been emphasized in the past, successful hemiarthroplasty is predicated on anatomic placement of the prosthesis with anatomic healing of the tuberosities. This approach requires optimization of specific patients, implants, and surgical factors. The purposes of this article are to briefly review certain patient factors (anatomy, classification, diagnosis, and indications), discuss important implant-related factors, and highlight key surgical factors so that pitfalls may be minimized and the goals of anatomic reconstruction realized more frequently.
Introduction
Proximal humerus fractures represent 4% to 5% of all fractures and 50% of all humerus fractures, increase in incidence with age, are more common in females, and are a leading cause of visits to the emergency room or admission to the hospital. According to Neer, 80% of all proximal humerus fractures are nondisplaced and can be managed nonoperatively. However, recent data from a regional trauma center indicates that the incidence of displaced fractures may be higher than originally described by Neer. In his original description, Neer classified displaced fractures as 2-, 3-, and 4-part fractures or fracture dislocations, as discussed in more detail herein. Hemiarthroplasty was indicated for most 4-part fractures and fracture dislocations as well as selected 3-part fractures and fracture dislocations. As techniques for internal fixation have improved, many 3-part and 4-part fractures in young active patients are currently being treated with osteosynthesis rather than arthroplasty. Moreover, inconsistent results from hemiarthroplasty, particularly in patients older than 70 years, has led to the increased use of reverse total shoulder arthroplasty.
Hemiarthroplasty is still a viable alternative in many patients with proximal humerus fractures. As has been emphasized in the past, successful hemiarthroplasty is predicated on anatomic placement of the prosthesis with anatomic healing of the tuberosities. This approach requires optimization of specific patients, implants, and surgical factors. The purposes of this article are to briefly review certain patient factors (anatomy, classification, diagnosis, and indications), discuss important implant-related factors, and highlight key surgical factors so that pitfalls may be minimized and the goals of anatomic reconstruction realized more frequently.
Anatomy and classification
The proximal humerus can be separated into 4 parts: the humeral head, the greater tuberosity, the lesser tuberosity, and the shaft. The humeral head is retroverted in relation to the shaft and the humeral epicondyle by 20° to 35° with an average of 30°. The neck shaft angle is extremely variable but averages 135°. The center of the humeral head is most often offset posteriorly and medially with regard to the center of the humeral shaft. However, given the comminution that is usually present, the importance of recreating humeral head offset is unclear. The most superior aspect of the head is situated approximately 5 to 8 mm above the top of the greater tuberosity and approximately 5.6 cm superior to the most superior extent of the pectoralis major insertion. The bicipital groove separates the greater and lesser tuberosity and is, on average, angled approximately 30° more retroverted than the humeral head with respect to the epicondylar axis.
Understanding the muscle attachments on each fragment will aid in fixation of the fragments to the humeral prosthesis. The infraspinatus, supraspinatus, and teres minor attach to the greater tuberosity. As a result, this fragment is most likely to displace posteriorly and superiorly. The lesser tuberosity is most often displaced medially owing to the pull of the subscapularis. Similarly, the shaft is often displaced medially because of the strong pull of the pectoralis major tendon.
There are 3 common classification systems for proximal humerus fractures: the Neer classification, the AO classification, and the Hertel classification. Although reliability of these classification systems has been questioned, the most commonly used system is Neer’s, which is a modification of the system originally introduced by Codman. It is based on displacement of the 4 previously described anatomic segments whereby displacement is defined on plain radiographs as 1 cm or 45°. The Neer classification describes 2-, 3-, and 4-part displacement with or without dislocation along with certain special situations such as head-splitting fractures and head-impression fractures.
Indications, contraindications, and alternatives
Indications for hemiarthroplasty include classic (ie, not valgus impacted) 4-part fractures and fracture dislocations as well as selected 3-part fractures and dislocations, and certain special situations including head-split fractures and impression fractures ( Fig. 1 ). The more displaced the fragment, the more likely it is to have a negative impact on the blood supply to the humeral head. Displaced 4-part fractures have the highest likelihood of developing avascular necrosis. Studies report this to be between 20% and 30%. In younger patients (eg, younger than 60 years) with 4-part displacement, adequate bone quality, and an intact rotator cuff, open reduction and internal fixation is indicated if an anatomic or near anatomic stable reduction and adequate fixation can be obtained. In addition, patients older than 70 with 4-part displacement, particularly if they have multiple medical comorbidities or are too sedentary or noncompliant to complete postoperative rehabilitation, may be candidates for reverse arthroplasty. Three-part fractures in older individuals with osteoporotic bone, 3-part fracture dislocations, and fractures involving a split or compression of 40% or more of the humeral head may also be considered for hemiarthroplasty. In general, however, open reduction and internal fixation is possible and id preferred for the vast majority of 3-part fractures.
Contraindications to hemiarthroplasty include patients who are medically unable to tolerate surgery and patients with limited or no use of the involved arm because of prior neurologic injury. Patients with active infection are also poor candidates for implantation of a prosthesis. In addition, patients with a known prior rotator cuff tear are not likely to do well with a hemiarthroplasty. These patients will likely have a better outcome with reverse shoulder arthroplasty.
History
Evaluation of a patient with a proximal humerus fracture should begin with the mechanism of injury. High-energy injuries increase the suspicion for other concurrent injuries. Low-energy injuries raise suspicion of poor bone quality. An evaluation of the medical history for possible risk factors that resulted in injury or that may affect surgical management or postoperative outcome should be performed. For example, a patient with a history of stroke with contralateral weakness may be more reliant on the fractured extremity.
An evaluation of the patient’s living situation is also important. The surgical extremity will be protected in a sling for up to 6 weeks postoperatively. In addition, overall function will be limited for an extended period of time beyond that. Evaluation of the patient’s home responsibilities (ie, caring for other family members) and available help to assist the patient are critical for a smooth postoperative course. Patients may benefit from temporarily living with other family members, or from having a home health aide or nurse. Alternatively, patients may require discharge to a skilled nursing or rehabilitation facility from the hospital. Inattention to these details may result in noncompliance with postoperative rehabilitation, and activity restrictions and could jeopardize a successful outcome.
Prior shoulder and arm function should be assessed. Any prior shoulder pain needs to be investigated. A history of symptoms suggestive of rotator cuff disease should be thoroughly discussed. Any prior imaging of the shoulder should be assessed and prior surgeries reviewed. Unrecognized prior shoulder abnormality, especially involving the rotator cuff, may have a negative impact on hemiarthroplasty.
Appropriate patient expectation is also critical in optimizing the patient’s postoperative satisfaction. In most cases, the patient’s shoulder was normal before the fracture and they may expect it to be normal after treatment. It is important to set reasonable patient expectations before surgical intervention. On average, patients undergoing hemiarthroplasty for proximal humerus fractures will take a year to reach a plateau in recovery, and can expect a shoulder with no or mild pain and elevation of 90° to 120°. Their role in maximizing the result should be emphasized. Failure to set appropriate expectations before surgery can result in decreased patient satisfaction.
Physical examination
Physical examination of the involved shoulder is often limited because of pain. However, several key physical findings can affect surgical planning and overall outcome, and should therefore be elicited. Inspection of the shoulder area for open wounds or skin breakdown that may increase the risk of local cellulitis should be performed. Moreover, the level of swelling and bruising in the arm may require delay of the procedure for several days. An evaluation of the vascular status is mandatory, especially with displaced 4-part fractures. In particular, significant medialization of the shaft can place the patient at increased risk for vascular injury. Assessment of the distal pulses bilaterally should be performed. Any decrease in the pulse on the involved side should be further evaluated. Complete laceration of the axillary artery is rare, and is usually obvious and limb threatening. However, collateral periscapular circulation between the third part of the subclavian artery and the third part of the axillary artery will likely keep the extremity perfused, despite complete occlusion of the axillary artery. This situation most commonly occurs with intimal tearing near the origin of the anterior and posterior humeral circumflex arteries. Although this injury is not usually limb threatening, it often results in long-term cold intolerance and pain. The only clue to its existence may be a slight asymmetry in the strength of the pulse. When this is present, confirmation of axillary artery patency of either extremity with ultrasonography or arteriography is suggested.
Neurologic status should also be assessed. Visser and colleagues demonstrated a 67% incidence of nerve injury following proximal humerus fracture. Axillary nerve function should be assessed by documenting the motor firing of the deltoid muscle. Evaluating the sensation over the lateral arm is not an accurate gauge of axillary nerve function. Presence of an axillary nerve injury, especially if the head is anteriorly dislocated, may affect the timing and type of surgical intervention. Distal motor function should also be evaluated to assess for brachial plexus injury. A thorough examination of the cervical spine must be performed to assess for possible concurrent injury. An inadequately performed or documented neurologic examination is a potential pitfall that can affect overall outcome, possibly resulting in litigation.
Imaging
Radiographic evaluation of the fracture should include a trauma series as defined by Neer: an anteroposterior view in the scapular plane, a y-view, and an axillary view. These radiographs are often done in an emergency room setting, and frequently are inadequate. Pain may limit the ability to attain a standard axillary view. A Velpeaux view can usually be performed in lieu of the axillary view, with much less pain. If these 3 views are all optimal, advanced imaging may not be necessary. However, if any of the views is inadequate, especially the axillary view, a computed tomography scan should be obtained to rule out posterior dislocation of the head and to characterize all fracture lines, tuberosity displacement, and comminution. Three-dimensional reconstruction can be especially helpful, particularly if the glenoid image is subtracted. Understanding the location of the tuberosity fracture lines in particular will allow preoperative planning to exploit existing fracture lines during exposure, rather than creating new ones. The intertubercular fracture line is most commonly located approximately 1 cm posterior to the bicipital groove.
Implant factors
The past decade has seen a significant increase in implant options. Most implant manufactures offer a fracture-specific shoulder implant with multiple head sizes to match patient anatomy. Fracture-specific shoulder stems have been designed with features that are intended to assist the surgeon with anatomic placement of the stem, and optimal reduction and fixation of the tuberosities. These features include fenestrations for bone grafting, implant coatings that induce bone ingrowth, strategically placed holes for suture fixation, size and shape alterations to enhance canal fit for cementless use or tuberosity reduction, and intramedullary or extramedullary jigs for temporary fixation to allow for provisional assessment of stem placement. In addition, some systems provide radiopaque trial heads to aid in assessment of adequacy of reduction, particularly greater tuberosity to head height. The surgeon should be familiar with the specific design features of the stem being used and the rationale behind the specific design characteristics so that any potential advantages can be maximized.
Several recently introduced systems allow for a well-fixed hemiarthroplasty to be converted to a reverse shoulder arthroplasty without removing the entire stem. In most reported series of reverse arthroplasties, revisions of prior shoulder prostheses represent a substantial percentage of the cases, and revision of failed hemiarthroplasties for fracture are among the most common revisions. Therefore, use of a stem that can be converted to a reverse component clearly represents an advantage. Ultimately, the utility of this feature depends on placement of the initial implant. If the hemiarthroplasty has been placed anatomically, most systems allow some correction of version and inclination, either above the humerus or within it. However, some hemiarthroplasties may be so poorly placed that they must be removed. All other factors being equal, use of a convertible stem is advantageous.
Finally, the surgeon should be prepared for any circumstances that may be encountered, such as potential placement of an anatomic glenoid component, fixation of an unrecognized glenoid fracture, or placement of a reverse prosthesis primarily. In the latter instance, having a convertible system that can be used as either an anatomic hemiarthroplasty or a reverse arthroplasty may be advantageous.
Surgical technique
The patient is placed in the beach chair position with the head of the bed elevated 30° to 40°, and the operative arm draped so that is it freely mobile ( Fig. 2 ). It is important that the surgeon is able to adduct and extend the arm toward the floor to gain access to the humeral shaft. This setting is best accomplished by using either a commercially available beach chair positioner, which secures the head and allows a portion of the back of the bed to be removed, or a standard table with the patient positioned as far toward the edge as is safely possible with the shoulder and arm unsupported. A Mayfield headrest can be used to secure the head and improve access to the top of the shoulder. With either positioning scenario, a bolster should be placed along the ribs on the operative side to prevent inadvertent lateral movement of the patient during the case.
Intraoperative radiographic evaluation is strongly encouraged in all fracture cases. In most instances, intraoperative fluoroscopy is adequate. However, if image quality is poor or acquisition or interpretation is difficult for any reason, portable plain radiography should be available. Preoperative images should be available in the operating room. In addition, the C-arm should be positioned before the patient is prepped and draped to verify that adequate images can be obtained. The C-arm can be positioned parallel to the table, above the head on the operative side or perpendicular to the table from the opposite side. The latter configuration has the advantage of keeping the C-arm out of the way, but may be difficult when using a standard table.
An 8- to 10-cm incision is made extending inferiorly and laterally from the tip of the coracoid process toward the deltoid tuberosity. The cephalic vein is identified and retracted laterally with the deltoid muscle. Once through the deltopectoral interval, the surgeon will encounter substantial hematoma, which should be evacuated. At least initially, the pectoralis major insertion is preserved so that it can be used to confirm accurate head placement if necessary. In most cases, release of any of the pectoralis major is not required for adequate exposure. A self-retaining retractor is used to retract the pectoralis medially and the deltoid and cephalic vein laterally.
The conjoined tendon of the coracobrachialis and short head of the biceps is identified, and the clavipectoral fascia is incised just lateral to this tendon. This incision is carried superiorly to the coracoacromial ligament and inferiorly to the upper border of the pectoralis major insertion. There is no need to incise the coracoacromial ligament, and there may be some advantage to preserving it as a restraint to future anterosuperior subluxation. The surgeon’s finger is then swept medially, deep to the conjoined tendon, from superiorly to inferiorly, to identify the axillary nerve as it passes superficial to the subscapularis muscle belly toward the quadrilateral space. In general, the musculocutaneous nerve passes through the conjoined tendon approximately 5 to 6 cm distal to the tip of the coracoid, and is not within the immediate surgical field. However, this relationship is variable, and the nerve can be as close as 1 to 2 cm distal to the tip of the coracoid. If the musculocutaneous nerve is palpated in this latter position, retraction of the conjoined tendon should be minimized.
The bicipital sheath is then identified and incised. In the setting of an acute fracture there is often a significant amount of hematoma and hemorrhagic bursal tissue, which can make identification of the biceps sheath difficult. The sheath can be most easily identified at the inferior portion of the deltopectoral interval just superior to the pectoralis major. Because the pectoralis major tendon inserts on the lateral lip of the bicipital groove, palpation immediately deep to the pectoralis major insertion will identify the biceps tendon. The biceps can then be followed proximal to the pectoralis major insertion. Once the sheath is identified and opened, the biceps tendon should be traced superiorly to the transverse humeral ligament, which is preserved. This action identifies the bicipital groove proximally and should assist the surgeon in identifying the greater tuberosity fracture line, which is usually located approximately 1 cm posterior to the bicipital groove. This fracture line is widened and, at the superior aspect of the fracture, the soft-tissue is split parallel to the anterior border of the supraspinatus all the way to the glenoid. The biceps is then tenodesed to the upper border of the pectoralis major distally and released just proximal to this tenodesis site. The joint is accessed through the greater tuberosity fracture line and the split created at the anterior border of the supraspinatus. The biceps is then resected by releasing the intra-articular portion from the supraglenoid tubercle and pulling it through the transverse humeral ligament distally.
The humeral metaphysis should now consist of an anterior fragment that includes the bicipital groove and lesser tuberosity and a posterior fragment that includes the greater tuberosity. Either of these fragments may be comminuted. Therefore, care should be exercised in manipulating them. A heavy, nonabsorbable suture is placed through the bone-tendon junction of each of these fragments at the most lateral extent on each, adjacent to the major intertubercular fracture line ( Fig. 3 ). This action will assist in protecting the remaining bone during retraction. The anterior fragment is pulled anteriorly and the posterior fragment is pulled posteriorly, taking care to preserve as much of the periosteal connection between the fragments and the shaft as possible.
