Technique of Angular Stable Plate Fixation

Fig. 17.1

Five joints around the shoulder (Kanatlı U)

The prolonged life span leads to proximal humerus fractures as a common clinical condition in general orthopedic practice [2]. Although the different rates have been mentioned in the literature, the commonly accepted view is that it accounts for 4–5% of all fractures [3, 4]. It can be confronted as perfectly recoverable fractures without surgery, as well as complex fractures or fracture-dislocations in which even osteosynthesis is inadequate and which may require arthroplasty [5]. The fact that specialists interested in this subject have wide knowledge on the anatomical structure of the region and the type of the fracture as well as on the surgical approach are useful for achieving the best outcome in treatment.

Although proximal humerus fractures are seen at all ages, they frequently appear at older ages. In a 5-year prospective study involving 1027 patients, Court-Brown et al. [6] found that the mean age was 66 years and that the incidence of proximal humerus fractures was 3 times higher in women than that in men. In another study involving 586 patients, it was shown that the incidence of proximal humerus fractures was 4 times higher in women than that in men [7].

When risk factors for proximal humerus fractures are investigated, low bone mineral density and increased risk of falls can primarily be counted. In the elderly, proximal humerus fractures often occur due to low-energy traumas in the home. When the reasons of proximal humerus fractures are examined, low-energy falls constitute a large part (87%). Direct traumas such as falls from height (4%), traffic accidents (4%), sports injuries (4%), and assaults (1%) can cause proximal humerus fractures [6].

Although many direct or indirect factors may cause proximal humerus fractures, the trauma energy, biomechanics of injury, and anatomical features and vascularity of the humerus affect fracture type, classification, and treatment. The treatment to be administered to the patient should maximize the functional expectation of the patient and reduce the pain to the lowest level.

17.2 Pathoanatomy

The glenohumeral joint is the most mobile joint in the human body due to the excellent fit between bones, muscles, and soft tissues. It is mainly located between the humerus, scapula, and clavicle and connects the upper extremity to the axial skeleton. This provides the range of motion with four joints. The subacromial region in which many motions occur and most of joint pathologies develop has recently been considered as the fifth joint. The anatomy of the shoulder girdle can be examined as three parts as bones, muscles, and soft tissues (joints and ligaments). Bone structure is comprised of the proximal humerus, scapula, and clavicle.

The clavicle is one of the main bones of the glenohumeral joint and is anchored to the axial skeleton by a single, highly mobile joint. It plays a role in transmitting compression forces from the upper limb to the axial skeleton. The scapula is a large, triangular flat bone that is parallel to upper posterior thorax and extends from second to seventh ribs. The scapula lies approximately 30° forward of the coronal plane. The acromion and clavicle form the acromioclavicular joint. The subacromial space is between the acromion and the head of the humerus where subacromial impingement might be seen. The supraspinatus tendon exits through the joint from a space as a normally 9–10 mm in the coronal plane. The lateral corner of the scapula makes the main shoulder joint with the humeral head through the pear-shaped glenoid cavity. It has a retroversion angle of about 2–7°. The glenoid has also a superior inclination of 0–5°. The coracoid process extends forward and outward on the glenoid cavity.

The proximal humerus which articulates with the scapula at the glenohumeral joint consists of the head, neck, and greater and lesser tubercles. The supraspinatus, infraspinatus and teres minor muscles attach to the greater tubercle. On the front side, the subscapularis muscle attaches to the lesser tubercle. The bicipital groove between these two tubercles passes over the long head of the biceps muscle and attaches to the glenoid fossa [8, 9]. The angle between the humeral head and the humeral shaft is approximately 130–150°. The angle between the humeral body and the anatomical head of the humerus is approximately 45°. The humeral head is retroverted approximately 30° (0–50°) with respect to the epicondylar axis. The glenoid joint surface is much smaller than the humerus. Therefore, when the arm is lifted upward, the glenoid slides lateral and forward to hold the humeral head in the glenoid socket, and the scapula rotates forward and upward [10].

The shoulder joint, which has the greatest range of motion in the human body, performs its ability with three diarthrodial joints: the glenohumeral joint, the acromioclavicular joint, and the sternoclavicular joint. Because the scapula can move on the chest wall, the scapulothoracic joint, which is considered to be a functional joint, can be included in them.

All four rotator cuff muscles extend from the scapula to the proximal humerus. The biceps tendon and glenohumeral ligament are the most important components of shoulder stability together. They provide this stability with creating concavity compression by contracting together in the coronal and transverse planes (dynamic stability). The deltoid and supraspinatus muscles contract in the coronal plane during abduction and provide both motion and dynamic stability by compressing the humeral head to the glenoid. The teres major and minor muscles originate at the lateral part of the scapula. The teres minor muscle attaches to the greater tubercle of the humerus and performs an external rotation of the humerus. The teres major muscle attaches to the lesser tubercle of the humerus and performs extension and adduction of the humerus. While the supraspinatus muscle is innervated by the suprascapular nerve, the axillary nerve innervates the teres minor muscle and the subscapular nerve innervates the teres major muscle [9] (Fig. 17.2a, b).

../images/429740_1_En_17_Chapter/429740_1_En_17_Fig2_HTML.jpg — Fig. 17.2

(a) The superior view of rotator cuff. (b) The posterior view of rotator cuff (Kanatlı U)

Six arteries have been found to regularly contribute to the arterial supply of the rotator cuff tendons: suprascapular, anterior circumflex humeral, posterior circumflex humeral, thoracoacromial, suprahumeral, and subscapular. While all blood vessels of the supraspinatus tendon are filled with blood during shoulder abduction, the last 1 cm segment (critical zone) of tendon insertion site is filled with blood during shoulder adduction. The vascular supply of the proximal humerus is derived from the axillary artery, the anterior humeral circumflex artery (AHCA), the ascending branch of the anterior humeral circumflex artery, the arcuate artery, the posterior humeral circumflex artery (PHCA), the ascending branch of the posterior humeral circumflex artery, and the branches of the thoracoacromial artery and the suprascapular artery supplying the rotator cuff muscles. The fracture line passing through the humeral neck affects blood flow to the humeral head. In short fractures with medial calcar, all vascular structures that make anastomosis to the arcuate artery supplying the humeral head are injured. In fractures with a medial calcar greater than 8 mm in length, the head is supplied by preserving the ascending branch of the posterior humeral circumflex artery [9, 11, 12]. Although the AHCA is classically considered the most important structure that supplies the proximal humerus, recent studies have emphasized that the PHCA is at least as important as the AHCA. According to this study, since 64% of the head is supplied by the PHCA, it is emphasized that the risk of avascular necrosis is low in well-treated fractures in which bone integrity is preserved [13] (Fig. 17.3a–c).

../images/429740_1_En_17_Chapter/429740_1_En_17_Fig3_HTML.png — Fig. 17.3

(a) The vessels of proximal humerus. (1) Arteria axillaris, (2) AHCA, (3) the ascending branch of AHCA, (4) arcuate artery, (5) PHCA, (6) the ascending branch of PHCA, (7) toracoacromial and suprascapular branches, (8) intraosseous metaphyseal branch. (b) Short medial calcar fractures affect AHCA and long medial calcar fractures, that is, longer than 8 mm affect PHCA. (c) AHCA

In studies of avascular necrosis conducted according to the four-part Neer classification system [14], it has been emphasized that the fracture needs soft tissue support, and it has been reported that there is a difference in the rate of avascular necrosis according to different fracture types.

17.3 Clinical Evaluation

As in all types of fractures, the complete history and physical examination are also important in proximal humerus fractures. While it is focused on the shoulder region, injuries that may accompany the shoulder girdle, cervical region, and upper extremity should not be neglected.

True AP, lateral, or scapular Y views and axillary views are helpful for evaluation following physical examination. Computed tomography is the most appropriate evaluation method to determine the type of fracture and to plan treatment. Magnetic resonance imaging can be used if malignancies or rotator cuff injuries are suspected.

The AO classification (which divides proximal humerus fractures described in the previous sections into the classic 27 subgroups) or Kocher, Codman, Jacob, and Ganz systems can be used in the classification of fractures. The Neer classification is the most commonly used scheme for proximal humeral fractures. It separates fractures into fragments according to 1 cm of displacement or 45° of angulation and divides the proximal humerus into four conceptual and functional “parts” [14, 15].

Many humerus fractures can be treated with nonsurgical methods due to the low incidence of displacement. Besides shoulder sling, shoulder exercises are recommended as early as possible.

The basic functional status of the patient before fracture, dominant hand, and adaptation to rehabilitation program affect the treatment method to be chosen. In proximal humerus fractures, clinical conditions having an absolute requirement for surgery include open fractures and progressive neurovascular deficits. In addition, surgery should be considered urgently for fracture-dislocations that cannot be reduced. Other clinical conditions that require surgery include fractures being severely displaced or unstable after closed reduction, three- to four-part fractures, and greater tuberosity fractures greater than 5 mm preventing rotator cuff function [4, 5, 16].

17.4 Aproaches to the Shoulder Joint

17.4.1 Deltopectoral Approach

The anterior approach to the shoulder joint is the most commonly used surgical approach. Many regions of the joint are easily accessible.

The patient is placed in the supine position on the operating table. The operative extremity is approached to the edge of the operating table so that it can move freely. By placing an elevation between the scapula and the spine, the operative extremity is raised forward of the body. The venous pressure is reduced with the head of the table elevated to 30–45°, thus helping bleeding control. The patient’s head is slightly turned to the nonoperative extremity and is then fixed (Fig. 17.4).

../images/429740_1_En_17_Chapter/429740_1_En_17_Fig4_HTML.jpg — Fig. 17.4

The view of deltopectoral approach (Kanatlı U)

The skin incision starts from underneath the clavicle and the lateral border of the coracoid process and is obliquely advanced about 10–12 cm distally throughout the deltopectoral interval. After it is passed through the subcutaneous tissue, it is advanced from the medial border of the coracoid process toward the deltoid insertion. The cephalic vein is identified and released. It is preferably taken to the lateral or medial side. Since the cephalic vein runs in the deltopectoral groove, it helps us find the deltopectoral space. After the deltoid and pectoralis major muscles are removed, the deep fascia confronts us when the deep dissection is performed. When the deep fascia that is very thin is opened, the coracoid process and conjoint tendon confront us. When the conjoint tendon is dislocated medially with a blunt retractor, the minor tubercle and subscapularis muscle are reached. In addition, the cephalic vein runs through the intervenous plane (between the deltoid muscle innervated by the axillary nerve and the pectoralis major muscle innervated by the lateral-medial pectoral nerves). While the proximal humerus is reached under the capsule, the neck and distal part can be reached with the help of a blunt retractor [17].

17.4.2 Lateral (Deltoid Split) Approach

It is an approach that can be used to reach the head and neck of the humerus. However, caution should be taken because of the course of the axillary nerve in the deltoid muscle in the distal part. It is used mostly in large tubercle fractures, in surgeries associated with the subacromial bursa, and in rotator cuff repair [18].

As in the deltopectoral approach, the patient is placed in the supine position on the operating table, and the head of the table is elevated to 30–45°. An approximately 5 cm skin incision is made distally to the lateral border of the acromion. The incision should not be extended since it runs between the axillary nerve and deltoid fibers in the distal part. After the deltoid fibers are separated by the raphe connecting the anterior and lateral fibers by a blunt retractor, the subacromial bursa can be reached underneath the acromion. The bursa can be opened with a longitudinal incision to reach the lateral part of the humeral head and the rotator cuff muscles attached to the greater tubercle under the deltoid muscle (Fig. 17.5).

../images/429740_1_En_17_Chapter/429740_1_En_17_Fig5_HTML.png — Fig. 17.5

The view of lateral approach (Kanatlı U)

The axillary nerve that runs transversely 5–7 cm distal to the edge of the acromion is the most important structure to be protected. If the nerve is cut, there is denervation in the anterior deltoid fibers and is sensory loss in the skin overlying the lateral side of the deltoid muscle.

17.5 Surgical Technique

In patients in whom we consider plate and screw fixation, our preference is the deltopectoral approach in the beach chair position. After the approach is applied as mentioned above, in order to primarily provide the proper angle of view and to fully understand the anatomy of fracture, sufficient amount of soft tissue dissection is performed with an elevator or a finger so that the soft tissue support of fracture parts is not impaired. Then, the position, size, and bone quality of fracture fragments as well as the tendons of rotator cuff muscles and the long head of the biceps tendon are evaluated before reduction. After the anatomy of fracture is fully understood, No. 5 nonabsorbable sutures are placed into the rotator cuff tendons in such a way as to include the bone close to the bone-tendon junction as possible as by considering the fracture fragments (in order to help reduction if there is a displaced tuberosity fragment). Because these sutures are used for the manipulation and reduction of fracture fragments and are fixed to the plate after plate placement, they create resistance to the deforming forces of the rotator cuff vector [19].

It is tried to be reduced by the help of an elevator or a finger. In order for the vector of the pectoralis major muscle to not prevent the reduction, the pulling force can be reduced by moving the arm in adduction and flexion [20]. K-wires are used to provide temporary stabilization of particularly proximal parts before plate placement. The medial head-neck junction of the humerus should not be separated as much as possible, and the anterior circumflex humeral artery, which is important for the blood supply of the humeral head, should be preserved. The most important point to keep in mind for maintenance of stabilization in the reduction is to maintain medial continuity. Then, the length of the plate is adjusted according to the extension of the fracture to the humerus shaft. If the fracture configuration is appropriate, compression is first applied by pulling the humerus shaft toward the lateral side with non-locking cortical screws through the oval hole of the plate corresponding to the humerus shaft. The proximal parts are reduced by the manipulation of sutures during compression. When compression is completed, the greater tuberosity appears to be compressed in the proximal part of plate. The anterior-posterior, lateral, and oblique views are taken with the help of C-arm fluoroscopy, and the reduction and plate position are assessed. It should be kept in mind that one of the most important points in maintenance of reduction is to provide medial support. The ideal placement of locking plate used for the proximal humerus is the lateral side of the proximal humerus so that the anterior edge of the plate is as close as possible to the posterolateral aspect of the biceps tendon. It is very important that the proximal of the plate is completely inserted into the tuberosities so that it does not extend to the superior. Superior placement results in subacromial impingement. Therefore, when the first screw is placed through the oval hole of the plate corresponding to the humerus shaft, the plate may be displaced proximally and distally. If reduction and plate position are appropriate, unicortical locking screws are inserted into the humeral head (at least five or six divergent screws). While the proximal locking screws are inserted and the first cortex is passed by the drill, it is advanced until the subchondral area by depth gauge and K-wires. It should not be forgotten that at least two screws placed along the calcar are important in terms of maintaining stability. Then, the screw holes at the distal part are filled with locking or cortical screws, taking into account bone quality. The anterior-posterior, lateral, and oblique views are taken with the help of C-arm fluoroscopy, and reduction and screw length are checked. Before the procedure is terminated, proximal sutures are fixed to the plate to reinforce stability. If there is a tear in the rotator cuff, it should be repaired. The hemovac drain is placed, and the skin and subcutaneous tissues are closed (Fig. 17.6a–d).