6.2.3 Humerus, distal
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1 Introduction
Distal humeral fractures are challenging for surgeons. Problems with nonunion, malunion, infection, hardware failure, stiffness, and late osteoarthritis have been common although recent advances have resulted in more successful outcomes.
1.1 Epidemiology
There is a bimodal distribution of distal humeral fractures with respect to age and gender with peaks of incidence in young male and in older female patients. Most fractures are intraarticular and involve both columns (complete articular: C-type) or are partial articular fractures of the capitellum or trochlea (B-type) [1].
The goal of operative treatment is anatomical reduction of the joint and correct alignment of the metaphysis with stable fixation to allow active motion within a few days of surgery.
1.2 Severe osteoporosis
It may be difficult to achieve stable internal fixation in patients with osteoporotic bone, and nonoperative treatment or total elbow arthroplasty can be considered. However, total elbow arthroplasty requires strict activity limitations, will eventually loosen, and may be associated with severe complications that can be difficult or impossible to treat. Inactive patients generally do well with nonoperative treatment, either with a cast or with a sling or collar and cuff. Inactive patients that develop unstable nonunions can be treated with total elbow arthroplasty.
2 Evaluation and diagnosis
2.1 Case history and physical examination
In the elderly, a simple fall may cause complex fractures. Osteoporosis makes fixation difficult but it is still feasible [2]. Young patients usually suffer this fracture with a high-energy injury, and polytrauma is common. Physical examination must include all three major nerves that cross the elbow joint. The injury often results in hyperextension on an extended elbow and so open wounds are usually posterior. Vascular injury is not unusual, especially with open fractures, and this must be ruled out.
Compartment syndrome may occur when there is a displaced forearm or wrist injury in addition to an unstable elbow injury. Severe pain and the inability to tolerate finger extension, whether active or passive, suggest the possibility of compartment syndrome. Peripheral pulses should be palpated preoperatively, but remember, because of the excellent longitudinal collateral blood supply around the elbow, it is possible to have a pulse even when the brachial artery is injured. Some trauma teams prefer to have definitive plate and screw fixation before arterial repair, but given the potential for prolonged and difficult surgery to repair a complex distal humeral fracture, temporary stabilization with an external fixator or temporary shunting of the artery are also to be considered. Positioning of the patient and planning of the incisions should take into account the fact that the brachial artery cannot be exposed through a posterior skin incision.
2.2 Imaging
High-quality x-rays (AP, lateral, and oblique views), x-rays with traction, and computed tomographic (CT) scans can help with planning of surgery. Traction x-rays are obtained once the patient is anesthetized. Three-dimensional CT images with the radius and ulna removed can be helpful. Views of the uninjured side are occasionally helpful for planning.
3 Anatomy
The distal humerus forms a strong bony triangle (formed by two columns and the central trochlea) with the olecranon and coronoid fossa in the center. The lateral column has the capitellum on its anterior surface but the posterior surface is nonarticular and may be used as a site for a plate. The spool-shaped trochlea is central rather than medial and the axis of rotation lies slightly in front of and anterior to the humeral shaft. The lateral column curves anteriorly with the center of rotation but the medial column (including the medial epicondyle) are in line with the humeral shaft. Placement of a straight plate on the posterolateral surface of the humerus risks straightening of the distal humerus.
The coronoid and olecranon fossae accommodate the corresponding processes in terminal flexion and extension. For full movement, the anterior and posterior fossae must be clear of metal or scar tissue and the anterior translation of the trochlea with respect to the shaft must be restored. The collateral ligaments are essential for stability. The medial collateral ligament originates from the undersurface of the medial epicondyle where it is vulnerable to excessive dissection ( Fig 6.2.3-1 ).
4 Classification
It is important to differentiate fractures that involve one or both columns of the distal humerus (the bone between the base and apex of the olecranon/coronoid fossae) and fractures that involve the articular surface and perhaps the epicondyles but not the columns (capitellum and trochlea fractures). Single-column fractures are uncommon. Isolated lateral column fractures are usually simple but isolated medial column fractures tend to feature complex articular fragmentation including impaction (stable malalignment) of part or all of the trochlea. Most bicolumnar fractures involve the articular surface; extraarticular fractures of the distal humerus are relatively uncommon ( Fig 6.2.3-2 ).
5 Surgical indications
Displaced intraarticular fractures
Open fractures
Fractures with nerve or vascular injuries
Polytrauma
6 Preoperative planning
6.1 Timing of surgery
Urgent surgery for distal humeral fractures is only required for open injuries and vascular injuries with ischemia. Most are closed injuries and may be performed at an expeditious time. Planning includes the entire surgical tactic—antibiotics, patient positioning, surgical approach, bone grafting, etc—set out step by step ( Fig 6.2.3-3 ).
6.2 Implant selection
Depending on the type and site of the fracture there is a selection of implants that can be used.
A1 fracture (medial epicondylar avulsion fractures): Fixation is rarely needed in A1 fractures, as the principal injury is a dislocation. Widely displaced fractures are sometimes repaired. Screw fixation usually suffices. For larger fragments, 3.5 or 4.0 mm screws are more reliable than K-wires. Cannulated screws may facilitate the procedure.
A2, A3, and C1 fractures: Both-column or complete articular fractures are stabilized with two plates. Reconstruction plates 3.5 are easier to contour but limited-contact dynamic compression plates (LC-DCP) are stronger. The one-third tubular plate is too weak and should only be used as a buttress on the ulnar column and always in combination with a second, stronger plate. Precontoured locking compression plates (LCP) can also be used and are very helpful for low, transverse fractures (A3).
B1 fracture: Lateral column fractures can usually be repaired with a single lateral plate and screws.
B2 fracture: Medial column fractures often have complex articular fragmentation. An olecranon osteotomy may help to expose and repair the injury. Small articular fragments can be repaired with small headless screws, threaded K-wires, or absorbable pins. The trochlea is often out of place but stable (impacted). Make sure to reduce it into the proper position.
B3 fracture: Articular fractures of the capitellum and trochlea are secured with implants, such as headless screws, screws with countersunk heads, small threaded K-wires, or resorbable pins. When the posterior part of the lateral column is fractured, particularly when it is fragmented, a plate and screws (and potentially a structural bone graft) may help secure it.
C2 and C3 fracture: The precontoured LCP is the standard implant in this instance and may also come in a variable angle locking screw system. The C3 fracture is usually reconstructed in the young patient with a high-energy injury but in the elderly, osteoporotic individual, total elbow arthroplasty should be considered.
Total elbow arthroplasty is used sparingly. It is only appropriate in patients with limited functional demands or preexisting elbow arthritis [3].
Precontoured plates have been developed by several manufacturers and most of the newer designs incorporate locking head screws (LHS) providing angular stability and diminishing the chance that the screws will back out. These plates, such as the LCP, may be useful in patients with low columnar fractures, substantial metaphyseal comminution, or poor bone quality [4].
6.3 Operating room set-up
An extremity drape is applied to the affected arm making sure that sufficient coverage is achieved to access the surgical field ( Fig 6.2.3-4 ). The distal forearm is draped with a stockinette and fixed with a tape, and the bone graft site and the image intensifier are separately draped. Different imaging positions are usually achieved by rotating the patient′s arm, but at times it is necessary to rotate the image intensifier.
The surgeon sits or stands adjacent to the patient′s axilla. The assistant sits or stands opposite the surgeon. They may need to move to allow the image intensifier access. The operating room personnel are positioned directly in line with the arm between the two surgeons. The image intensifier is brought in from the head of the table. It is possible on some pedestal radiolucent tables to bring the image intensifier in from the opposite side of the table so it interferes less with the surgical field. The image intensifier display screen is placed in full view of the surgical team and the radiographer ( Fig 6.2.3-5 ).
7 Surgery
7.1 Surgical approaches
The patient can be positioned supine (with the arm draped over the body), lateral decubitus (with the arm over a bolster or in an arm holder), or prone. In the lateral decubitus position, the arm rests on a rolled up pillow, in a gutter support or over a padded bar of about 4 cm diameter allowing 120° flexion of the elbow ( Fig 6.2.3-6 ). The supine position with the arm supported on a hand table is preferable for B3 fractures when an extended lateral exposure is used. If the fracture proves more complex than anticipated, the arm can be draped over the body and an olecranon osteotomy performed. A bone graft is rarely needed but with complex fractures it is wise to advise the patient of the possibility and prepare a donor site. In most cases, a sterile tourniquet is placed high on the arm but should be inflated only if excessive bleeding obscures the view for surgical dissection, for example, during dissection of the ulnar nerve. When the exposure is complete, the tourniquet can be released for reduction and fixation.
All aspects of the elbow can be accessed through a midline posterior skin incision raising medial and lateral flaps as needed ( Fig 6.2.3-7a ). The advantages of a posterior skin incision include:
Avoidance of major cutaneous nerve branches
Access to all parts of the elbow (including anterior) through a single incision
A relatively benign scar
Disadvantages include a longer scar and the potential for hematoma or skin problems with the extensive skin flaps, although in practice wound and skin problems are unusual after upper extremity surgery. If the wound is extended proximally toward the middle of the humeral shaft, care must be taken to protect the radial nerve. Some surgeons avoid an incision over the point of the olecranon, while others see no problem with a straight incision. A direct lateral incision can be used for isolated fractures involving the capitellum and trochlea.
The optimal handling of the ulnar nerve is still debated. A large percentage of bicolumnar and medial column fractures benefit from a plate that extends near or into the cubital tunnel. The ulnar nerve needs to be mobilized to secure many fractures. Most surgeons completely release and move the ulnar nerve temporarily during internal fixation. Some surgeons leave the nerve in the anterior subcutaneous tissues and others replace the nerve back into the groove.
Occasionally, the fracture can be secured with the ulnar nerve exposed but not moved. This might help limit the potential for ulnar neuropathy from devascularization and handling of the nerve.
To aid future surgery, it is essential that the operation record clearly describes how the ulnar nerve was handled and its position in relation to the implants. A diagram can be very helpful.
Extraarticular fractures can be repaired accurately through a triceps-splitting exposure (eg, Campbell [5, 6]) and this is particularly useful for open fractures, most of which have a rent in the triceps posteriorly where the shaft of the humerus has protruded. This rent can be extended into a Campbell exposure. Extraarticular and simple articular bicolumnar fractures can be approached with a triceps-split approach in which a midline split of the triceps brachii muscle is created and elevated away from the posterior humerus and olecranon. These fractures may also be reduced accurately leaving the triceps insertion intact by working through medial and lateral windows by using a triceps-elevating exposure (eg, Alonso-Llames, Fig 6.2.3-8 [7]).
The preferred exposure for an articular fracture is debated. An olecranon osteotomy gives excellent extensile exposure but exposes the patient to adverse events related to the osteotomy. These complications are associated with the creation, fixation, and healing of the osteotomy. A second surgery to remove bothersome olecranon implants may be a fair trade for achieving good reduction and fixation of the fracture.
Problems associated with an olecranon osteotomy can be limited by using a careful and meticulous dissection with specific techniques for creating and repairing the osteotomy [9].
Since a transverse osteotomy is inherently unstable, a distally pointed chevron osteotomy is preferable ( Video 6.2.3-1 ). The osteotomy is initiated with an oscillating saw and completed by fracturing the subchondral bone, levering the osteotomy open with an osteotome. Cracking the anterior cortex facilitates repositioning and increases stability of fixation due to interdigitation of the fragments ( Fig 6.2.3-7b , Fig 6.2.3-9 ).
The olecranon osteotomy is reconstructed according to the tension band technique described in chapter 3.2.3.
Alternatives to olecranon osteotomy include the triceps-elevating exposures, such as the Bryan-Morrey approach, a useful option when conversion to total elbow arthroplasty is an option, ( Fig 6.2.3-10 ) [8]. Triceps-elevating exposures do not provide as good a view of the articular fracture but the intact olecranon can act as a useful template for joint reduction, and this approach avoids the complications of osteotomy.