Introduction

Fractures of the distal humerus are complex and demanding injuries to treat. Understanding the anatomy of the distal humerus and the various fracture patterns is crucial for achieving a satisfactory outcome.

The humerus flattens and widens distally, with the maximum width between the epicondyles. The distal articular segment is held by the medial and lateral columns of thick cortical bone. A thin plate of bone between the columns constitutes the olecranon fossa posteriorly and the coronoid fossa anteriorly. This accommodates the olecranon and coronoid processes on extension and flexion respectively. The medial column diverges from the humerus at an angle of 45° and the proximal two-thirds are made of thick cortical bone, but the distal part is composed of soft cancellous bone. The triangular shape of the medial column enables screw placement for fracture fixation. The lateral column diverges from the humeral shaft at about 20° and has cortical bone similar to the medial column and also allows good fixation for screws. The distal part of this column is complex, with soft cancellous bone. The capitellum forms part of the lateral column.^1,2 It has a curved anterior articular surface that articulates with the radial head. Posteriorly the surface is non-articular and therefore can be used for screw placement, although care should be taken not to penetrate the articular surface (Fig. 16.1A, B). The common extensor origin from the lateral column and the flexor origin from the medial column are responsible for fracture fragment rotation following injury.

Figure 16.1 The anatomy of the distal humerus.

From Ross LM, Lamperti ED, consulting eds. Thieme atlas of anatomy. Georg Thieme: Stuttgart; 2006.

The articular portion projects anterior to the shaft of the humerus at about 40° in the sagittal plane; hence it is not well exposed through a posterior approach (Fig. 16.1C). It also has a valgus angulation of 4–8° to the shaft in the coronal plane.³ Restoring the articular anatomy and stabilizing the two columns without impingement of the fossae by metalwork is the key to successful surgical management of these complex injuries.⁴

Background/aetiology

Distal humeral fractures have a bimodal age distribution, affecting the young (high energy) or the elderly (low energy). Peaks of incidence have been noted in males aged 12–19 years and in females aged 80 and older. The most common mechanism of injury is axial loading of the distal humerus, by a simple fall. The next most common causes of fractures are road traffic accidents and sport.⁵

Fractures of the distal humerus account for approximately 2–6% of all fractures and about 30% of all elbow fractures.⁶ One epidemiological study from Finland showed that the age-adjusted incidence of osteoporotic fractures of the distal humerus increased, from 12/100 000 women in 1970 to 28/100 000 women in 1995 and it predicts a threefold increase by the year 2030.⁷

Classification

Various classification systems have been proposed for distal humeral fractures. In 1969 Riseborough and Radin developed a system of classifying T-shaped intercondylar fractures of the distal humerus based on the degree of fragment displacement, rotation and comminution.⁸ The AO group devised a classification system dividing the distal humerus into three types based on fracture lines lying extra-articularly, intra-articularly with or without involvement of a single column, and intra-articularly involving both columns. Stepwise progression into grouping and subgrouping of these fractures is dependent on the site of the fracture lines and the degree of fracture comminution. Fractures that do not fall into any of the three types or nine groups are labelled type D or .4, respectively.⁹ Later, Mehne and Jupiter developed a classification system based on three broad groups of fractures. Intra-articular fractures are subdivided into those with either single-columnar or bicolumnar involvement or those involving the capitellum or trochlea. Extra-articular, but intracapsular, fractures are also subdivided depending on the proximity of the fracture to the joint. Epicondyle fractures represent extra-articular fractures in this classification.¹ In an assessment of these classification systems, Wainwright et al concluded that they were neither reliable nor reproducible, and thus their usefulness in decision making and comparison of outcomes was questionable.¹⁰ More recently, a clinically useful classification for fractures of the distal humerus has been developed and validated.¹¹ This classification system has three main components – extra-articular, predominantly intra-articular and predominantly articular (Fig. 16.2) – based on plain AP and lateral radiographs. The classification system was found to be both substantially reliable (k, 0.664) and reproducible (k, 0.732). It achieved superior inter-observer and intra-observer agreement compared with the other three classification systems, with a low proportion of unclassifiable fractures. A management algorithm used with this classification aids the surgical decision-making process for these complex fractures (Fig. 16.3).

Figure 16.2 New classification for fractures of distal humerus.

Figure 16.3 Management algorithm for distal humerus fractures.

Presentation and investigations

Classically patients present with a swollen, deformed elbow. The skin over the elbow may be disrupted as a result of the direct injury to the elbow. Careful neurological and vascular assessment of the distal extremity should be undertaken and recorded before any form of treatment is commenced.

Once a clinical diagnosis has been established, plain anteroposterior and lateral radiographs should be performed to confirm the diagnosis (Fig. 16.4A). Further imaging with a CT scan may be helpful in assessing the type of fracture and the number and orientation of the fragments (Fig. 16.4B). More recently, three-dimensional reconstruction CT scanning has been used (Fig. 16.4C). Although these require more time and may increase the overall cost of imaging, they have been shown to be easier to interpret than two-dimensional scans and are helpful in identifying the components and special orientation of complex articular fragments. This can be particularly helpful for preoperative planning of complex fracture fixations.¹²

Figure 16.4 (A) Plain radiographs of a patient with an open distal humerus fracture. (B) 2-D CT scan of the fracture. (C) 3-D reconstruction of the fracture.

Surgical technique and rehabilitation

The treatment of distal humeral fractures depends on the general condition of the patient and the type of fracture. The patient should be fit to have a prolonged anaesthetic and should be fully informed of the likely outcome of the procedure. The surgery should ideally be undertaken by a surgeon experienced in treating these injuries. He or she should have adequate resources and sufficient time to perform the operation. Inadequate surgical stabilization (i.e. K-wire stabilization) will result in poor outcomes, and salvage of failed surgery can be extremely challenging.

The patient should be positioned laterally with the upper arm horizontal and the forearm hanging vertically. This position allows excellent exposure for both internal fixation and prosthetic replacement. A high tourniquet should be applied.

A posterior incision centred on the tip of the olecranon is utilized. Although many surgeons place the incision just lateral to the tip of the olecranon it is our preference to make the incision on the medial side of the olecranon. This reduces the size of the posteromedial skin flap and facilitates identification of the ulnar nerve. The nerve must always be found and decompressed but whether anterior transposition is undertaken is a matter of surgeon preference.

The next stage of the surgical approach is dependent on whether internal fixation or joint replacement is to be performed. If internal fixation is to be undertaken it is important to have adequate exposure of the fracture in order to permit rigid reconstruction. We utilize the treatment algorithm outlined above.

If the fracture does not involve the articular surface, a paratricepital approach to the fracture usually provides adequate exposure, whereas if the articular surface is involved a chevron osteotomy is preferred. If an olecranon osteotomy is performed this should be undertaken through the non-articular portion of the bone midway between the olecranon and coronoid processes.

Reconstruction initially involves debridement of the fracture fragments, after which the fragments must be anatomically repositioned. Traditional AO advice involves reconstructing the articular surface, after which the articular portion of the fracture is reattached to the humeral shaft. Although this approach may be entirely appropriate for some fractures, it has been our experience that it is preferable to start the reconstruction with any fragments that clearly belong together and then build the reconstruction on those fragments. Preliminary fixation can be achieved using bone clamps and K-wires. Definitive rigid fixation must then be obtained by plating the fracture. This can be achieved using either the AO 90/90 plating technique or the more recently advocated parallel plating method.

With the AO method a reconstruction plate is usually applied to the medial border of the distal humerus with a dynamic compression plate on the posterolateral surface. Both plates will require bending to conform to the shape of the distal humerus. For this reason it is important to be fully aware of the distal humeral anatomy as inappropriate contouring of the plates will result in either a malunion or non-union of the fracture.

Pre-contoured plates have the significant advantage that when they are placed against the humerus, if they do not line up against the bone it is the bone that is in the wrong place rather than the plate. Knowledge that this is the case can be extremely useful when dealing with complex fractures, particularly if there are any fragments of bone missing.

Following fixation of the fracture the olecranon osteotomy should be reconstructed by tension band wiring or plating.

With articular fractures an olecranon osteotomy is the preferred surgical approach as this gives the greatest exposure of the articular surface. Once the fracture has been reduced and preliminarily held, definitive fixation can sometimes be achieved using the plating techniques described above but, in addition, supplementary fixation using headless screws may also be required.

If a preoperative decision is made that the fracture is not reconstructable, then either a hemiarthroplasty or total joint replacement should be considered. These options are described in Chapters 18 and 19.

Postoperatively we place patients who have undergone open reduction and internal fixation in a backslab with the elbow at 90° for between 7 and 10 days. This allows the soft tissue swelling to settle and we believe reduces the risk of wound problems, particularly if there has been excessive swelling preoperatively. In contrast, when a total joint arthroplasty has been performed the elbow is splinted in extension for 48 h, after which the wound is inspected. Provided the wound is satisfactory the patient is allowed to begin active progressive elbow flexion and extension exercises.

Treatment options, outcome and literature review

Predominantly intra-articular fractures

The goal of treatment in these fractures is to restore articular anatomy and provide stable fixation, enabling early motion. The complex anatomy, substantial forces across the elbow joint, and frequently diminished bone density make fixation technically demanding and explain the relatively high complication rates. The majority of non-unions (as high as 75%) in this region are caused by inadequate primary fracture fixations;⁶ hence stable initial fixation with early motion is the key to a good outcome.

Historically these fractures were treated non-operatively using the ‘bag of bones’ method or plaster immobilization with minimal fixation techniques.¹⁶ The outcomes, however, were poor compared to stable fixation¹⁷ and non-operative treatment is now only used for patients with multiple comorbidities who are unfit for surgery. The gold standard for management of these fractures is open reduction, rigid internal fixation and early mobilization.

The surgical approach requires good exposure of the articular fragments and the distal humeral shaft. This can be achieved adequately by an olecranon osteotomy¹⁸ (apex distal, chevron) at the level of the bare area of the olecranon with proximal reflection of the triceps. An olecranon osteotomy is particularly useful in complex articular injuries since it is often difficult to be certain that an accurate articular reconstruction has been achieved if the olecranon is left intact. Pre-drilling holes to fix the osteotomy prior to performing the osteotomy helps in anatomical reconstruction of the olecranon at the end of the procedure.

Careful isolation and protection of the ulnar nerve are needed during fracture exposure, owing to its close proximity to the medial epicondyle. The fracture haematoma is removed, taking care to avoid loss of small bone fragments. The fracture anatomy must be fully identified if the fracture is to be successfully reconstructed. It is important to begin the reconstruction by starting with fragments that clearly fit together. These may be held with temporary wires or fracture reduction clamps. Once adequate reduction of the fragments is achieved, definitive fixation using plates and screws can be performed. The plates may need to be contoured to the distal humerus or, alternatively, pre-contoured plates may be used. The pre-contoured plates have the advantage of providing a template onto which the fracture can be reduced. Most modern plating systems can be used in locking, non-locking or hybrid modes. The locking plates provide a fixed angle construct, which acts as a scaffold in supporting the osteopenic distal humerus. The plates are either placed in a 90–90 (posterolateral and medial) (Fig. 16.5) or a parallel (medial and lateral) (Fig. 16.6) configuration to support the medial and lateral columns. The 90–90 configuration is the traditional AO method of fixing the distal humerus. The procedure involves fixation of the articular fragments, and then fixation of the articular segment to the humeral shaft with the two plates.

Figure 16.5 Traditional 90–90 plating technique.

Figure 16.6 Parallel plating. This patient was referred having initially been treated with an external fixator because of an open fracture and ulnar nerve symptoms. Fixation of the olecranon osteotomy was undertaken using an olecranon rod. At operation a small quantity of bone was noted to be missing from the distal humerus.

Biomechanical studies have shown locking plates to provide superior bone implant anchorage in osteoporotic (bone mineral density < 420 mg/cm³) and comminuted fractures of the distal humerus, but have shown no difference in good-quality bone when fractures were fixed with the 90–90 technique.¹⁹ In addition, superior stiffness to bending and torsion has been reported with parallel plating when compared to the 90–90 technique.²⁰ Clinical studies have also shown superior results with parallel plating.²¹ The parallel plating technique is described in more detail in Chapter 17.

Articular fractures

Management of fractures involving the articular surface depend on the physiological age of the patient and the quality of the articular fragments. If the patient is elderly and adequate fixation cannot be obtained, hemiarthroplasty or total elbow replacement can be considered. This option should be available at the time of surgery and the patient warned preoperatively that this may be necessary depending on the operative findings.

Internal fixation

Intra-articular fractures of the distal humerus in young and active individuals should be managed by internal fixation. Good-quality imaging helps identify the various fracture patterns, and this is essential for preoperative planning. Various patterns of injury of the distal humerus have been described. Ring et al produced a descriptive classification based on the configuration of the fracture and described five components of the distal humerus: (1) the capitellum and the lateral aspect of the trochlea; (2) the lateral epicondyle; (3) the posterior aspect of the lateral column; (4) the posterior aspect of the trochlea; and (5) the medial epicondyle.²² The surgical approach to these fractures is dependent on the type of fracture.

Isolated capitellar fractures are rare. Bryan and Morrey described three types of capitellar fractures: type 1 is a shear type of fracture in the coronal plane involving most of the capitellum, with little or no trochlear element but with good subchondral bone; type 2 is a capitellar fracture with a thin shell of subchondral bone; and type 3 is a comminuted or compression fracture of the capitellum.²³ This classification does not address capitellar fractures that extend into the trochlea. A more recent classification proposed by Dubberley et al is more useful in managing these injuries. This classification has three types: type 1 is primarily a capitellar fracture, which is approached through Kocher’s approach; type 2 fractures involve the capitellum and the trochlea as one fragment; these fractures are best exposed through combined lateral and medial incisions or via an olecranon osteotomy; in type 3, the capitellar and trochlear fragments are separate and these are comminuted shear fractures. An olecranon osteotomy is the preferred approach for these fractures (Fig. 16.7). When posterior wall comminution is recognized in any of the fractures, it is further subclassified as a type B injury.²⁴ If the capitellum, lateral trochlea and the lateral epicondyle are involved, then a lateral approach with distal reflection of the lateral epicondyle with its soft tissue attachment provides adequate exposure of the fracture fragments and facilitates fixation using headless cannulated screws after temporary wire fixation. The lateral epicondylar fragment is then reattached using a screw or tension band wiring technique. If the medial epicondyle is fractured with a small medial articular fragment a medial approach to the elbow can be used. The olecranon and radial head can be used as a template to reduce the fracture, taking care to elevate any posterior impaction.

Figure 16.7 The typical appearances at operation of a comminuted articular fracture. For this type of fracture an olecranon osteotomy provides the greatest articular exposure.

Various internal fixation devices have been used to fix intra-articular fractures. Biomechanical studies have shown that posteroanteriorly directed cancellous lag screws are significantly more stable than anteroposteriorly directed screws, but the conical headless screw (Acutrak) was significantly more stable than posteroanterior cancellous screws.²⁵ Comparison between the types of headless screws showed the Acutrak screws to be superior to Herbert screws.²⁶ In the presence of comminution, supplemental bone graft and/or plate fixation should be considered.²⁴

Ring et al reported good to excellent results in 16 of 21 patients who had open reduction and internal fixation of articular fractures of the distal humerus at a mean follow-up of 40 months. The average arc of movement at the ulnohumeral joint was 96°. Ten patients required a second operation (six had contracture release, two for ulnar nerve decompressions, one needed revision fixation and one had removal of metalwork).²² More recently, Dubberley et al reported functional outcomes in 28 patients with a mean follow-up of 56 months. The average Mayo performance index was 91±11, with a mean range of motion of 19–138°. Two patients with comminution had non-union requiring total elbow arthroplasty.²⁴

Total elbow replacement

Although anatomical reduction and fracture fixation is the treatment of choice for distal humeral fractures, the presence of comminution and osteopenia makes this a demanding and difficult procedure in the older patient. For this reason total elbow arthroplasty has been advocated as an alternative surgical option.²⁷ It is indicated in elderly patients with low demands, patients of any age with inflammatory arthritis, pathological bone or reduced life expectancy, or in patients with non-unions who are over the age of 70. Good to excellent medium-term results with linked prosthesis have been reported in rheumatoid and non-rheumatoid patients.^28,29 A retrospective review of 48 patients treated primarily by a total elbow arthroplasty for distal humeral fractures reported an average Mayo elbow performance score of 93 (maximum possible 100) at a mean follow-up of 7 years. Rheumatoid arthritis was present in 40% of the patients.²⁸ A recent study of 26 non-rheumatoid patients who had linked total elbow replacement for distal humerus fractures reported a mean Mayo elbow performance score of 92 at 63 months follow-up.²⁹ Unlinked total elbow replacements have also been used for distal humeral fractures, and although early results are promising no long-term results are available.³⁰

A prospective randomized multicentre trial comparing open reduction and internal fixation and primary semi-constrained total elbow replacement for comminuted intra-articular fractures in patients over the age of 65 reported better outcomes after a total elbow replacement at 2 years compared to open reduction and internal fixation.³¹ A study comparing total elbow arthroplasty undertaken as a primary procedure for distal humeral fractures in the elderly, with total elbow arthroplasty after failed internal fixation or conservative treatment at a mean follow-up of 56.1 months, reported no significant difference between the two groups.³² The place of total elbow arthroplasty for distal humeral fractures is dealt with in greater detail in Chapter 19.

Hemiarthroplasty:

Hemiarthroplasty has recently been advocated for young patients with comminuted distal humerus fractures that cannot be reconstructed. It is covered in more detail in Chapter 18.

Summary Box 16.2 Surgical approach

Complications of treatment

Complications occurring following the surgical treatment of distal humeral fractures may present early or late.

Early complications include neurological and wound problems, while residual stiffness, malunion and non-union do not usually become apparent until some weeks after surgery.

In order to minimize the risk of neurological complications it is essential during the fracture reconstruction for the surgeon to find and protect the ulnar nerve. In addition for fractures that extend proximally the radial nerve must also be identified and protected. Provided the surgeon is confident that the neurological anatomy has not been damaged during the surgical procedure, any postoperative sensory and/or motor dysfunction is likely to be a neuropraxia, which will normally recover within 2–3 months.

Wound problems are more likely to occur in patients with excessively swollen and bruised elbows. To reduce this risk, thick skin flaps should be raised and the elbow immobilized in extension in order to take the tension off the skin edges.

The management of postoperative stiffness is dealt with in Chapter 20.

Malunion and non-union of distal humeral fractures can be particularly challenging to treat. They will usually require further surgery, with debridement of non-united bone fragments, bone grafting and replating. Ali et al³³ reported their experience of treating 16 patients with distal humeral non-unions. They noted that although non-unions occurred in all decades from the second to the ninth they were most common in patients aged between 41 and 50 years (31%). They found no association with gender, a history of smoking or mechanism of injury. When, however, they analysed other publications,^34,35 including the AO classification of the original fracture, they noted that non-unions were more frequently associated with fractures that had a supracondylar component. They also stated that they considered the primary treatment of the original fracture to be suboptimal in 12 of their 16 patients (75%). Fractures had been fixed using only K-wires, screws or inadequate plates (Fig. 16.8).

Figure 16.8 Non-union of distal humeral fractures. (A) Initial fixation with wires. These broke and revision surgery was undertaken with plating. (B) Plating with screws. The screws became loose and revision surgery was performed using plates. (C) Inadequate fixation with plates requiring revision surgery.

From Ali A, Douglas H, Stanley D. Revision surgery for nonunion after early failure of fixation of fractures of the distal humerus. J Bone Joint Surg (Br) 2005; 87-B:1107–1110.

Conclusions/personal view

Distal humeral fractures are extremely difficult and time-consuming injuries to treat. As such it is our opinion that if a patient is to get the best possible result following their injury the surgeon must have sufficient experience and time available to perform the reconstruction. If this is not possible it is better for the patient to be transferred to a specialist unit than to have inadequate surgery that will require a revision procedure.

Our personal approach is to clinically assess the patient with particular reference to the distal neurovascular status of the arm. We will then critically examine the radiographs and if necessary have them repeated or obtain a CT scan. We believe it is essential to obtain as much information as possible about the fracture before advising on management.

If the patient is clearly unfit, with multiple medical comorbidities, we will consider conservative treatment but only after assessment from a physician and anaesthetist.

The majority of patients will be treated surgically. This is never undertaken at night unless the patient has associated life- or limb-threatening injuries. We prefer to operate on these fractures when we are alert and have adequate time available.

Most patients will undergo open reduction and internal fixation. We use both the traditional AO plating and parallel plating methods, depending on the fracture configuration. For comminuted articular fractures we prefer to use congruent parallel plates as we find these more useful in this type of fracture. In elderly patients with grossly comminuted fractures we will consider a total elbow arthroplasty. We have no experience of hemiarthroplasty.