6 Open Reduction and Internal Fixation of Proximal Humeral Fractures Using Locking Plates

Fractures of the proximal humerus, representing 5% of all extremity fractures, are common fractures. Apart from the distal fracture of the radius and fractures adjacent to the hip joint, the proximal humerus fracture is the most common fracture in elderly people. The incidence in the total population is 70 per 100,000 per annum, but this rises in women over 70 years to 400 per 100,000 per annum.1 In contrast to the more common indirect type of accident experienced by older people, injury in younger people is likely to be the consequence of high-energy trauma.

Operative stabilization of fractures of the humeral head is still a surgical challenge and remains the subject of many clinical and experimental investigations. The large number of implants currently available on the market and the different recommendations for operative stabilization procedures reflect the problems involved with this injury and its treatment. From the point of view of evidence-based medicine, it is still not possible to define the gold standard for stabilization of fractures of the humeral head.^2,3

New findings about the biomechanics and pathophysiology of bones and soft tissue have influenced and directed the design and function of new forms of osteosynthesis. In particular, the development of locking implants has strongly influenced modern surgical techniques.

Anatomy of the Proximal Humerus

Due to blood flow dynamics in the area of the proximal humerus, the risk of a necrosis developing in the humeral head because of surgical manipulation is high, and can result from the fractures alone. The blood supply of the proximal humerus is provided mainly by the circumflex humeral arteries, which branch off the axillary artery. The ascending branch running through the area of the bicipital groove is significant as it also flows through a substantial part of the calvaria.^4,5 Recently, using more refined preparation and drainage techniques, additional periosteal irradiating vessels were identified in the area of the lesser tubercle in the humeral head. This periosteal blood flow is only disturbed when the humeral head suffers gross dislocation and usually continues to ensure residual blood flow to the calvaria. Studies also show that the periosteal blood flow plays an important role in the area of the calcarine spur and that the size of the fracture fragment and the extent of the dislocation permit conclusions to be drawn about the risk of necrosis developing in and around the humeral head.⁶ Manipulation during surgery can also slightly upset or even destroy the blood flow. Blood flow is usually further reduced by the pressure of conventional plates/screws on the periosteum. This problem is eliminated by the use of locking implants.

Classifications of Proximal Humeral Fractures

Codman drew up a classification in 1934, which was based on the four segments: the greater tubercle, the lesser tubercle, calvaria, and shaft. Neer compiled the classification most widely used now; it is based on Codman’s four-fragment classification and is divided into six groups. According to the Neer classification, surgery is indicated when all four fragments are involved, with a dislocation of the fragments of at least 0.5 to 1 cm or with more than a 45-degree tilt.^7,8 Various studies, however, have shown that there are difficulties with the practical application of this classification.^9–12 It has not been possible to generally implement the AO classification according to Müller et al.^12–14

The low reliability of these classifications causes difficulties in the numerous clinical comparative studies. According to accident records, which often lack technical details but must used as a main basis for classification, the question arises whether it is possible at all to make a precise assessment of the degree of dislocation of the individual segments using these initial records. However, taking conventional x-rays in one to three planes is still the standard diagnostic procedure for the proximal humerus. If the extent of the fracture cannot be assessed a computed tomography (CT) scan is indicated.10 This is especially helpful if there is a possibility of a comminuted fracture of the calvaria and of so-called head split fractures, which the classifications do not describe adequately. Codman’s classification is still practical because it is not based on the dislocation of the individual fragments that is difficult to assess, but focuses on the instability of the fragments affected.

Treatment

In principle, both surgical and conservative treatment can be considered for fractures of the proximal humerus. Although Neer intended his classification to be an aid for determining the indications for conservative or surgical treatment of proximal humerus fractures,^7,8 it has not resulted in a gold standard for the treatment of proximal humerus fractures according to the criteria of evidence-based-medicine.^12,15 The advantages and disadvantages of conservative and surgical procedures are still controversial; very good as well as poor outcomes for both procedures are described.^16,17 However, there are still not many prospective or even randomized studies with locking implants. Our own prospective trial is in progress.

In our clinic, we tend to advocate a surgical procedure–we have had good results with locking implants even when the bone quality is poor. In our opinion, shoulder function profits from early functional rehabilitation.

Surgical Treatment

In past decades, various methods of surgical stabilization were used. Until the 1980s, the standard technique was to use various conventional plates such as T-plates or one-third tubular plates, which are still used in some cases today.^3,18–21 The use of angled blade plates is also described in the recent literature.²² However, these nonlocking plate fixations cause damage to soft tissue and allow extensive bone exposure. Many cases also result in typical complications such as implant failure, loss of reduction, and necroses of the humeral head.^3,18,23 Problems have also arisen from the choice of implant–plates with higher stability are bulkier, which further compromises the soft tissue. Smaller implants, such as one-third tubular plates, show too little stability and are often unsuitable, particularly in cases of low bone quality.

Because of these problems, the future trend is toward minimal fixation procedures.^3,18,24 This term applies to stabilization procedures that offer fixation using a minimally invasive approach. The procedures include Kirschner wire (K-wire) fixations in (partially) open or closed technique, cerclage wire fixation or PDS (polydioxanone) sutures, and isolated percutaneous screws, which have been used as conventional small fragment screws or inserted as cannulated screws over guide wires.^23–27

These changes in surgical technique are revealing the problems of stabilization procedures at the proximal humerus and the need for the development of new implants. The priority is the preservation of the soft tissue; to this end, blood flow must be maintained to the greatest possible extent.

Locking Plates

In the past, the aim of internal fixation was to achieve the best possible anatomical reduction and then to fix the bone in this position. If conventional plates were used as implants, a relatively large approach with complete exposure was necessary.²⁸ This resulted in additional damage to the soft tissue, which encouraged infections and impaired healing of the bone as well as the soft tissue.^29,30 The stabilizing principle of conventional plates results from the friction between plate and bone.²⁸ The pressure exerted by the plate through the strong application of the screws on the bone suppresses the blood flow of the periosteum, which further impairs healing of the fracture.

Accordingly, to avoid this additional alteration in blood flow, the principle of internal fixation was developed and initially implemented in the form of the point contact fixator (PC-Fix) and the LISS (less invasive stabilization system).³¹ Using the principle of internal fixation, reduction can be maintained through implants–analogous to external fixation–without suppressing the blood flow by the pressure applied. Hence, the locking compression plate (LCP) was developed and modified for different anatomic regions (for example, the distal tibia plate, the pilon plate, the locking proximal humerus plate [LPHP], the distal humerus plate, etc.).³² This new generation of locking plates combines the advantages of the conventional techniques of dynamic compression (DC plates) with the advantages of the internal fixator.³¹ The plate is no longer being pulled toward the bone by the screws; therefore, the periosteal blood flow is no longer compromised. In addition, comminuted fractures can also be bridged with the locking plates and reduction maintained without risking a secondary loss of reduction through collapse of the fracture parts, as nothing in the locking system changes in terms of the plates and/or screw angles. Retention by the implant is therefore maintained. The biological insertion of the implants by the so-called minimally invasive percutaneous osteosynthesis technique (MIPO) is possible with these plate systems, which guarantees less damage to the soft tissue and better bone healing. Locking implants are also very well suited for use in osteoporotic bones.

Advantages of Locking Plates at the Proximal Humerus

The plates are also biomechanically not as stiff as other implants designed for this region, which has a positive effect on load capacity and is also better suited to osteoporotic bones. Furthermore, the plates sit very firmly in the bone due to the (converging/diverging) screw orientation and the locked screw anchorage.33 The locking head screws ensure that the periosteal blood flow is not too severely impaired, which stimulates the healing of the fracture and counteracts the danger of a necrosis of the humeral head. In addition, functional physiotherapy can be started directly after the operation because of the locked fixation of the fragments, without the risk of the screws becoming loose and/or secondary loss of reduction.

Locking Plate Systems

In our department, we use the LPHP (Fig. 6–1) and the PHILOS (proximal humerus internal locking system) (Fig. 6–2) as the standard implants for the stabilization of proximal humerus fractures. There are only slight differences between both plates. The long PHILOS plate is preferred for long fractures, which may still have comminuted areas. The LPHP, being slightly less thick, puts even less pressure on the soft tissue and it is more likely that a postoperative impingement syndrome will be avoided. The PHILOS plate may possibly provide greater stability as it has a greater number of screws in the head area, greater variability, and perhaps higher stability for certain fractures.

Related posts:

Nonunions and Malunions of Monteggia Fracture Dislocations Nonunions of the Clavicle Reconstruction of Posttraumatic Stiffness and Instability Arthroplasty for Proximal Humeral Fractures Total Elbow Arthroplasty for Distal Humeral Fractures Complex Fractures of the Distal Humerus

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