Fracture Medial Epicondyle

B Extension Valgus Ulnar metaphysis fracture +/- medial epicondyle avulsion +/-radial neck fracture... 

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 %). 

Avulsion fractures of the medial epicondyle are seen between the ages of 9 and 15, after the apophysis becomes a separate ossification nucleus from the epiphysis of the distal humerus and before it fuses with the distal humerus. The medial epicondyle is a traction apophysis for the flexor group of forearm muscles, and also serves as an attachment for the ulnar collateral ligaments and the joint capsule. This injury accounts for up to 10% of elbow fractures. 

Fig. 18.15a,b. Two children with moderately a and minimally b displaced fractures of the medial epicondyle... 

Fig. 18.16. a Fracture of the medial epicondyle associated with dislocation of the elbow (type IV). b Image intensifier radiograph demonstrates reduction of the elbow but the epicondyle is stuck in joint rather than in an anatomical position - arrowed, c Epicondyle fixed in correct position. 

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. 

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. 

The medial and lateral epicondyles are extracapsular and fractures of these structures are not associated with capsular distension or displacement of the fat pads. 

---