Olecranon Fractures

Introduction

Olecranon fractures exhibit a bimodal distribution: low energy injuries in the older age group and higher energy mechanism in the younger population. The mechanism of injury often dictates the fracture pattern. An indirect injury results from a fall onto an outstretched hand. As the hand touches the ground, a forceful contraction of the triceps muscle pulls a portion of the olecranon off in an avulsion or oblique fashion. This is in contrast to a direct mechanism in which a force is applied directly to the olecranon, leading to a more comminuted fracture pattern.

Anatomy

The ossification center of the olecranon appears around age 10 and fuses at about 16 years.

The olecranon position lends itself to fracture as it is a subcutaneous bony prominence. It represents the posterior aspect of the elbow joint. The trochlea of the distal humerus is a wide articular surface that has a groove in its center that coincides with an edge in the center of the semilunar notch (aka greater sigmoid notch) of the ulna. The semilunar notch is defined as the area between the tip of the olecranon and the tip of the coronoid process.

The articulation between the trochlea and the anteromedial facet of the coronoid, along with the radiocapitellar joint account for the intrinsic osseous stability of the elbow joint. There is a transverse ridge on the semilunar notch known as the bare area, which is devoid of articular cartilage.

On the olecranon the triceps tendon inserts and surrounds the joint capsule. In similar fashion to the patella, an olecranon fracture corresponds to a functional disruption of the extensor mechanism of the elbow joint.

Classification

There are several classifications systems used for olecranon, and proximal ulna and radial fractures.  No one classification is universally used: 

1. AO Classification:
   1. Type A: Extraarticualar fractures at the metadiaphysis level.
   2. Type B:  Intraarticular fractures of either the radius or ulna
   3. Type C: Complex fractures of both the proximal radius and ulna.
      
2. Schatzker Classification
   1. Transverse fracture through deepest point of the trochlear notch usually resulting from sudden pull of the tricep.
   2. Complex transverse fracture with comminution or central, articular impaction from a direct force.
   3. Oblique fracture usually from hyperextension.
   4. Comminuted fractures with associated fracture of the coronoid process.
   5. Oblique fracture distal to the midpoint of trochlear notch. (Tension band fixation is inadequate)
   6. Olecranon fracture with associated radial head fracture and possibly medial collateral ligament injury.
      
3. Mayo classification
   1. Type I: Non-displaced fractures.  The fracture may be either non-comminuted (Type IA) or comminuted (Type IB).
   2. Type II: Displaced, stable fractures.  The proximal fracture fragment is displaced more than three millimeters, but the collateral ligaments are intact and there is no elbow instability. The fracture may be either non-comminuted (Type IIA) or comminuted (Type IIB).
   3. Type III: Displaced, unstable fractures: The proximal fracture fragment is displaced and the forearm is unstable in relation to the humerus. This is a fracture-dislocation. It also may be either non-comminuted (Type IIIA) or comminuted (Type IIIB).

Presentation

The patient will present with a swollen, abrased elbow supported by the contralateral extremity. Abrasions should be assessed for possibility of open elbow fracture. The swelling is due to the intra-articular nature of the injury.

Due to proximity to the fracture site and zone of injury, the ulnar nerve should be paid close attention during neurovascular exam. It is symptomatic approximately 10% of the time.

Diagnosis

1. As in any trauma situation, the patient should be evaluated according to the Advanced Trauma Life Support protocol.
2. In low energy falls, especially in older patients, the mechanism of injury should be thoroughly evaluated to make sure there is no underlying medical cause (e.g. syncope).  Associated injuries such as distal radius fractures, cervical spine injuries and hip fractures should also be considered in this population.
3. The skin should be examined for open injuries.  If a splint is on, it must be removed.  Typically there is a significant amount of subcutaneous swelling and bruising.  A depression at the fracture site can sometimes be appreciated.
4. In all injuries, specifically the higher energy injuries, a thorough and well-documented neurovascular exam should be performed.  Specific attention should be given to ulnar nerve function and anterior interosseus nerve injury, seen in Monteggia injuries (discussed in the next section).
5. Initial radiographs are often limited due to pain.  The personality of the fracture and other possible associated injuries can be assessed, typically on the lateral projection.
6. Post-manipulation radiographs or a CT scan may provide additional information for fracture-dislocations or when radial head or coronoid process fractures are suspected.

Treatment

1. Non-operative
- Non-displaced fractures in which the extensor mechanism is intact may be treated without surgery.
-The elbow should be immobilized in 30 degrees of flexion for at least 6 weeks. 
-Repeat radiographs should be obtained at one week to look for displacement of the fracture.
-It is rare to treat non-operatively because of the length of time needed for immobilization and the risk of stiffness.

2.      Operative
a.      Surgical Planning
-The patient can be positioned in either supine with the arm across the chest or lateral decubitus/prone with the arm draped over a padded support.
-Either a sterile or non-sterile tourniquet applied at the upper arm can be used.
-General or regional anesthesia (e.g. axillary block) can be utilized.
-A midline posterior skin incision is utilized incorporating open wounds if present.  A curvilinear approach that does not pass directly over the olecranon can be used but may cross more cutaneous nerves.
-The ulnar nerve usually does not need to be isolated.

b.      Surgical Techniques
Tension band wiring (Figure 2)
-Used for simple fractures at the level of the transverse groove
-Failure to recognize distal extension or more complex injury will lead to fixation failure.
-After inspection to rule out more extensive comminution and after reduction, two parallel 0.062 or 0.045-inch Kirschner wires are passed through the fracture site and through the anterior cortex distal to coronoid process
-One or two holes are drilled transversely across the ulna distal to fracture site.
-One 18-gauge or two 22-gauge stainless steel wires are passed through the holes and placed in a figure-of-eight configuration. The proximal part of the wire is passed through the insertion of the tricep.  The wires are tensioned with two loops on both sides of the figure-of-eight configuration.
-This technique converts tension forces into compression forces at the fracture site.
Intramedullary screw technique
-Can be used in lieu of tension band wiring for simple fractures
-A large 6.5mm cancellous screw is placed down the shaft of the ulna to grab the distal cortex
-Complications include malreduction and distal ulna fracture.
-A tension band can supplement screw fixation.
Plate and screw fixation
-Used for comminuted fractures, Monteggia fractures and olecranon fracture-dislocations (discussed in the next section)
-Dynamic compression plates are used.  One-third tubular plates are not adequate for fixation.
-Plates can be placed dorsally, medially, or laterally
-The plate should contour around the proximal ulna to increase the number of screws that can be placed proximally.
-The tricep insertion can be incised longitudinally to place the plate directly on bone.
-Anatomic restoration of the coronoid and olecranon process is critical and the remaining comminution can be bridged.
Excision and tricep advancement
-This technique is rarely indicated as primary treatment.
-It may be used in significantly comminuted, osteopenic bone for infirm, older patients with low functional demands.
-This technique is contraindicated with collateral ligament, radial head, or coronoid process injury
-After excision of the fragments, the tricep is attached with large grasping sutures through drill holes just below the articular margin.
-Excision of larger pieces has greater potential for elbow instability.
 
c.       Postoperative Management
- Active range of motion should be initiated the day after surgery.
-Resistive exercises should be delayed till early healing is seen at 6-8 weeks.

-Tenuous fixation or excision and tricep advancement should be immobilized for 4-6 weeks before exercises are started.

Complications:

1. Hardware Failure

-Occurs in up to 5% of patients. 

-Tension bands fail if used for comminuted or complex factures.
-Plates may fail if not properly contoured or placed either medially or laterally.

2. Hardware prominence
- Symptoms from hardware have been reported as high as 80%. 
-This can be prevented by seating the Kirschner wires in the olecranon, positioning the twisted wire loops away from the skin, and longitudinally incising the tricep tendon to place a plate directly on bone.
3. Infection
- Infections are unusual and occur in more complex injuries.
4. Nonunion
-Nonunions are unusual especially for simple fractures.
5. Ulnar Neuropathy
-May occur in up to 5% of cases.
-Usually resolves with conservative management.
- Symptoms may develop as late as 4-6 weeks in which case the neuropathy may benefit from a release.
6. Heterotopic ossification and stiffness
-Stiffness is common is elbow injuries but it is uncommon in olecranon fractures.
-Stiffness increases with complexity of the fracture.
-Heterotopic ossification may occur and has been reported in up to 13% of cases.

7. Arthrosis

-Severe arthrosis is uncommon.

-Some level of arthrosis may be seen in up to 20% of patients

Red Flags and Controversies:

Hardware irritation is very common. It is reported in up to 71% of cases in which tension band is used. K-wires may also back out, this is less likely to occur if the wires are engaging the volar cortex of the ulna rather than passing down the canal.

Biomechanical studies have shown braided cable to be stronger than stainless steel wire.

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