Olecranon Fractures

A number of equivalent lesions have also been described. Commonest of these is the Type 1 variant Where the radial head is dislocated anteriorly but the ulna has plastic deformation rather than a fracture. Other variants include dislocations with associated radial neck fractures, olecranon fractures and dislocations of the ulnar-humeral joint. In some respects, the pulled elbow , commonly seen in infants, can also be considered a Bado I equivalent. The injury occurs when the elbow has traction applied, usually resulting in hyperextension and pronation. The radial head subluxes through the annular ligament but does not truly dislocate and radiographs are either normal or will show an effusion with elevation of the fat pads. 

Sleeve avulsion fractures are a particular form of avulsion injury seen in the unossified skeleton which differs from avulsions in adults because the sleeve of periosteum which is pulled off can continue to form bone if not treated. The typical location is at the lower pole of the patella, but the upper pole of the patella, the olecranon and the medial epicondyle can also be affected. Ultrasound demonstrates a sleeve of cartilage that has been avulsed usually with a small fragment of bone (Hunt and Somashekar 2005). In some cases a double cortical sign may be present, indicating elevation of a superficial layer of cortex from the underlying bone. There maybe associated haemarthrosis and patella alta (Fig. 4.14). 

An estimation of the distribution of fracture patterns about the elbow is supracondylar (70%), lateral condyle (15%), medial epicondyle (10%), olecranon (5%), radial neck (1%), medial condyle (1%), capitel-lum (1%), T condylar (<1 %). 

The blood supply to the capitellum is via end arterioles from the inferior ulnar collateral artery crossing the olecranon fossa posteriorly into the lateral condyle to the ossific nucleus of the capitellum. This predisposes to avascular necrosis following displaced capitellar fractures. 

Three fat pads lie over the capsule, the anterior over the coronoid fossa, the posterior over the olecranon fossa and a third over the supinator as it wraps over the radius. Fracture, haematoma and effusion into an intact capsule may cause capsular distension, which can distort these fat pads, improving their visibility and identifying occult fractures (Fig. 18.4). In the setting of acute trauma, a visible... 

Some fractures may be reduced by closed manipulation and stabilisedby percutaneous K-wires. Evaluation of fracture reduction may be aided by intraoperative arthrogram. The most stable and therefore ideal configuration of K-wires is for a common entry point on the lateral edge of the condyle, with one wire running transversely to the medial condyle, and the second at about 60 aiming at the medial cortex above the olecranon fossa. 

Fractures of the radial neck maybe isolated injuries but can occur in association with medial epicondyle avulsions, fractures of the olecranon and dislocations of the elbow joint. 

Olecranon fractures are occasionally seen in children and account for about 5% of fractures about the elbow. Fortunately, the majority of injuries are minimally displaced, and are managed non-operatively. A significant number of fractures have associated injury either to the elbow or to the wrist. 

Metaphyseal fractures can be classified according to mechanism of injury. The majority of injuries occur with the elbow in extension, the olecranon locked in the olecranon fossa and the maximum stress developed in the proximal metaphyseal region leading to fracture. When a valgus stress is applied, there may be asso ciated compression fractures of the radial neck and avulsion of the medial epicondyle. Varus stress is associated with radial head subluxation. 

Injuries with the elbow flexed during a fall occur as the olecranon is stressed over the fulcrum of the trochlea as the triceps attempt to resist the force acting on the distal ulna (Fig. 18.20). The line of fracture is oblique and intra-articular. This mechanism may also produce an extensor avulsion of the apophysis. 

In a flexed elbow, a direct blow to the posterior aspect of the ulna, just anterior to the distal humerus, can cause a shear stress on the olecranon metaphysis, breaching the anterior cortex and with the radius and distal ulnar fragment displaced anteriorly by the pull of the brachialis and biceps. This may occur with the elbow either flexed or extended, leading to either a transverse or oblique fracture pattern (Table 18.2). 

Fig. 18.20. Flexion type (Wilkins A) fracture of the olecranon through the metaphysis...

Treated isolated fractures of the olecranon have been shown to have an excellent long-term outcome (Gicquel et al. 2001). Delayed union and malunion are possible complications of early displacement of... 

Childress HM (1975) Recurrent ulna nerve dislocation at the elbow. Clin Orthop 108 168-173 Evans MC, Graham HK (1999a) Olecranon fractures in children. J Pediatr Orthop 19 559-569 Evans MC, Graham HK (1999b) Radial neck fractures in children a management algorithm J Pediatr Orthop Part B 8 93-99... 

Distal triceps tendon tear is an uncommon condition that mostly occurs at or close to the olecranon process of the ulna, often associated with a fleck of bone attached to the retracted tendon as a result of avulsion fracture (Fig. 8.47). The mechanism involves either forced flexion of the elbow against a contracting triceps, as occurs during a fall on an outstretched arm, or relates to a direct blow onto the olecranon process. Local steroid injection into the olecranon bursa, anabolic steroid abuse and pre-existing tendinosis may also have a role in the tendon rupture. As a rule, complete tears occur more... 

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