PROXIMAL HUMERAL FRACTURES
Fractures of the proximal humerus are common, occur- ring most frequently in older patients from a fall on the outstretched hand.
The fragment is considered displaced if the displacement is greater than 1 cm or the angulation is greater than 45 degrees. The four-part classification proposed by Neer requires identification of the following four major fracture fragments and their relationships to one another on initial radiographs: (1) articular segment, (2) greater tuberosity with the attached supraspinatus muscle, (3) lesser tuberosity with the attached subscapularis muscle, and (4) humeral shaft. The fractures can be associated with dislocation of the humeral head segment, in which case they are classified as a fracture and dislocation. For example, the fracture may involve the greater tuberosity and the humeral head may be dislocated anteriorly (see Plate 1-21). This is called a two-part fracture dislocation. These injuries have particular clinical importance regarding the nature of the tissue damage treatment and prognosis. For example, a common fracture-dislocation involves the greater tuberosity and anterior dislocation of the humeral head. In these cases, closed reduction of the humeral head may result in persistence of displacement of the greater tuberosity requiring surgery for reduction of the fractures (see Plate 1-21). In contrast, if the closed reduction of the humeral head results in a close approximation of the greater tuberosity, then surgery is not needed but, more importantly, recurrent dislocations of the humeral head after the fracture is healed are rare because tearing of the glenohumeral ligaments does not occur because the fracture of the greater tuberosity and the soft tissue damage to the rotator cuff allows for dislocation to occur with treatment of the glenohumeral ligaments.
Likewise, variations of proximal humeral fractures include damage to the articular head segment (see Plate 1-25). When damage occurs to the humeral head segment, then this is a variant of the classic four-part classification. In most cases, replacement of the humeral head is required to manage both the long term sequelae of avascular necrosis (loss of blood supply) to the humeral head and the post-traumatic arthritis resulting from trauma to the articular cartilage.
The Neer classification of proximal humeral fractures includes two-part, three-part, and four-part fractures. Two-part fractures may involve the anatomic neck or the surgical neck or the greater tuberosity or lesser tuberosity. Three-part fractures include the humeral head segment and either the greater or lesser tuberosity. Four-part fractures include both tuberosities, the humeral head segment, and the humeral shaft. In four-part fractures with wide displacement, the humeral head is isolated from its blood supply and there is a higher incidence of avascular necrosis.
Diagnosis, and resulting classification, of proximal humeral fractures is confirmed from radiographs taken in at least two orthogonal planes (90 degrees from one another) and should include an anteroposterior view and a transscapular Y view of the shoulder. When possible, a modified axillary view should be obtained. In many cases with acute fracture an axillary view is difficult to obtain because of pain associated with fracture and the arm position needed to obtain this view.
Computed tomography (CT) with multiplanar reconstruction or three-dimensional reconstruction allows for better determination of the number of parts and their displacement. In some fractures, each of the major segments of the proximal humerus may have more than one fracture line (i.e., comminution). In these cases, the fractures are classified using the four-part classification with the added modification of the term comminution to the segment involved. In other words, these are not called five or six-part fractures. In the cases in which one or more segments of the proximal humerus are fractured but there is minimal displacement of any of the segments, then these fractures are considered one- part fractures to indicate that none of the fragments is displaced or requires surgical reduction. For example, an isolated fracture of the greater tuberosity without displacement would be called a one-part fracture involving the greater tuberosity or a minimally displaced fracture of the greater tuberosity.
Two-Part Greater Tuberosity Fracture
A displaced fracture of the greater tuberosity by definition as described previously requires isolated involvement of the greater tuberosity with displacement of more than 1 cm. In the example shown, the displacement is superior as seen on the anteroposterior view and posterior as seen on the axillary view. This finding represents disruption of the surrounding soft tissue and tearing of the rotator cuff tissue to allow this fragment to displace. The supraspinatus, infraspinatus, and teres minor are attached to the greater tuberosity. These rotator cuff muscles function to elevate and externally rotate the arm. A fracture of the greater tuberosity of this large-sized fragment will result in the ability of these rotator cuff muscles to pull the fragment superiorly and posteriorly. Surgery is required for placing the fragment in its proper location to restore proper rotator cuff strength and to avoid loss of motion due to malunion of the fragment. Malunion will cause impingement of the malunited fragment on the posterior aspect of the glenoid when attempting external rotation of the arm or impingement on the undersurface of the acromion when attempting elevation of the shoulder.
Posterior displacement will also result in shortening of the posterior capsule, resulting in loss of internal rotation. Treatment of the late sequelae of a malunion is very difficult and often results in a less-than-ideal functional outcome. Early recognition of these dis- placed fractures is important for early surgical intervention. If an anatomic reduction is achieved with stable fixation, then healing and rehabilitation can result in normal shoulder function and no pain. Several types of surgery can be performed to achieve this goal. In the case shown, the fracture was treated with open resection and internal fixation with heavy suture material. This technique is best used in the older patient with osteoporosis when fixation using screws may fail owing to poor fixation of the screw between the bone fragments. Suture fixation between the tendon insertions of the rotator cuff is much stronger than fixation isolated to the bone fragments. Suture fixation is also better when there are multiple small fragments of the greater tuberosity (see Plate 1-25).
With isolated fracture of the greater tuberosity in patients with good quality bone, minimally invasive reduction under fluoroscopy and screw fixation can be done as an effective, less invasive alternative to open reduction and suture fixation (see Plate 1-24).
Two-Part Surgical Neck Fracture And Dislocation Of The Humeral Head
Fractures along with dislocation of the humeral head segment is a common variation of the four-segment classification of proximal humeral fractures. The clinical significance is related to the additional damage caused to the articular cartilage of the humeral head, the additional trauma to the blood supply to the humeral head, and the additional trauma to the glenoid and glenohumeral ligaments. Each of these can result in additional long-term adverse clinical sequelae, specifically post-traumatic arthritis, avascular necrosis of the humeral head, glenoid arthritic changes, or instability of the joint. Each of these additional problems makes surgery necessary to manage this problem and also increases the urgency for early surgical invention. It should be noted that the difficulty in diagnosis of the dislocated part of the fracture pattern on the anteroposterior radiograph reinforces the need for the axillary radiographic view and an axial CT image. It is also difficult to see the fracture of the humeral head segment on the anteroposterior radiograph. These types of fractures are often missed in the office or emergency department setting if inadequate imaging is performed. When this occurs, early surgical invention is not per- formed; and in some cases the patient is treated without surgery, resulting in a very poor outcome. Late reconstructive surgery for management of the late sequelae of malunion of this fracture often results in improvement but a less than favorable outcome when compared with early fracture management.
In this case of a young middle-aged and active person who fell from a horse, open surgery for an anatomic reduction of the fracture and reduction of the dislocation resulted in the ability to use minimal fixation devices because of the high-quality bone tissue and an anatomic reduction allowing for interfragment compression fixation using the lag screw concept. The distal screw was a cortical screw for the cortical bone using overdrilling of the lateral fragment, resulting in compression at the fracture site, with the screw orientation being perpendicular to the fracture line, thus resulting in compression of the fracture. The superior screw is a partially threaded cancellous screw placed into cancellous bone of the humeral head. The larger treads of the cancellous screw achieve better fixation in cancellous bone. The smooth part of the cancellous screw allows for the lag screw again effecting compression across the fracture site. Again the screw is placed perpendicular to the fracture line, maximizing the compression effect and fracture fragment stability with the use of a minimal implant and avoiding a large plate (see Plate 1-23).
Valgus-Impacted Four-Part Fracture
A valgus-impacted four-part fracture is a variation of a classic four-part fracture-dislocation. In a classic four-part fracture-dislocation the humeral head segment is completely separated from the other three segments of the proximal humerus (greater and lesser tuberosity and the humeral shaft). In many of these classic four-part fractures the humeral head segment is also dislocated from the joint and is not articulating with the glenoid. When the articular segment is separated from its blood supply (see Plates 1-16 and 1-17), there is a high incidence of avascular necrosis. In most cases these fractures occur in the elderly, and humeral head replacement using a stemmed prosthesis as shown in Plate 1-25 is the preferred treatment for reduction and fixation of the tuberosities and replacement of the avascular articular segment.
The valgus-impacted four-part fracture results in rotation of the humeral head articular segment into a horizontal position with impaction of this segment between the fractures of the greater and lesser tuberosities that become split and widened to accommodate the impacted humeral head. With this fracture, the humeral head segment is oriented with the articular surface facing superiorly toward the undersurface of the acromion. The humeral head is not in contact with the glenoid and is shrouded by the displaced tuberosities. In many of these fractures the periosteum on the medial side of the humeral shaft and humeral head segment remains intact and forms a soft tissue bridge between the two, adding to the stability of the head segment and to its blood supply. This results in a much lower incidence of avascular necrosis than that seen with classic four-part fracture-dislocations. Both the greater and lesser tuberosity fracture fragments are displaced laterally but keep an intact soft tissue attachment to the humeral shaft. As a result of these soft tissue attachments, this fracture configuration allows for keeping the humeral head and fracture in reduction and fixation rather than displacement. It is important to recognize this specific fracture pattern both for the ability to keep the humeral head segment and more importantly to not confuse this with a minimally displaced fracture that would otherwise be treated nonoperatively. If the medial soft tissue hinge is present and providing some stability of the head segment, then a more minimally invasive method of fracture reduction and internal fixation can be accomplished as shown at the bottom of Plate 1-24. When there is more instability of the fragment, comminution of the segments, or poor bone quality secondary to osteoporosis, then a more formal operation with open incision with plate fixation as shown at the top of Plate 1-24 is preferred.
Open reduction and internal fixation provides more rigid internal fixation but does require a larger open procedure. When a minimally invasive reduction and fixation is performed, a small incision (1 to 2 cm) is placed distal to the fracture site and under fluoroscopic control the humeral head segment is elevated into an anatomic position using a blunt instrument placed under the humeral head segment at its superior part, thereby rotating it out of its valgus position. As a result of the soft tissue attachments to each of the fragments, elevation of the head fragment with traction on the arm easily realigns the tuberosities under the humeral head segment. Percutaneous pinning and screw fixation pro- vides sufficient fixation of the segments to maintain the reduction. This is not ridged fixation, and removal of the pins at 6 weeks after surgery allows for sufficient healing to begin rehabilitation. Because of the minimally invasive approach, delay in rehabilitation does not result in the vast majority of patients achieving good range of motion, assuming that the fracture fragments maintain good position.
Patients treated in plate fixation generally have better fixation and can and should start rehabilitation range-of-motion exercises soon after surgery.
Humeral Head Split With A Classic Four-Part Fracture-Dislocation
The classic four-part fracture-dislocation can be associated with a fracture through the articular surface of the humeral head. These fractures generally occur in higher-velocity and higher-energy trauma. The fracture through the humeral head segment results in a much more difficult fracture to manage and generally requires humeral head replacement. In addition, the likelihood for post-traumatic arthritis and avascular necrosis in this fracture configuration is certain, again making humeral head replacement the treatment of choice. With humeral head replacement, the stem of the prosthetic is securely placed into the shaft of the humerus, in most cases by the use of bone cement. One of the most difficult parts of the surgery is to place the stem in the correct height and rotation to reproduce the normal pre-fracture anatomy. When done correctly, there will be the same amount of space between the metallic humeral head and the shaft as there was before the fracture in order to place all of the fracture fragments of the greater and lesser tuberosities within this interval so that the fragments are below the metallic humeral head and above the humeral shaft. Fixation of these fragments is aided by use of the metallic stem as an internal fixation device, around which the fragments are reduced with the humeral head in place. Very heavy and strong nonresorbable sutures are placed through the humeral shaft bone and prosthetic as well as through the rotator cuff tendons that are attached to the tuberosity fragments. Despite the multiple fractures and fragments of bone, when an anatomic reduction is achieved with good fixation, long-term outcome is excellent.