儿童肘关节骨折

,Elbow - Fractures in Children,Fracture mechanism,HyperextensionInjury to the elbow joint is usely the result of hyperextension or extreme valgus due to a fall on the outstretched arm.Scroll through the images on the left to see how hyperextension leads to a supracondylar fracture.The hemarthros will result in a displacement of the anterior fat pad upwards and the posterior fat backwards.,Extreme valgus,The other important fracture mechanism is extreme valgus of the elbow.The normal elbow already has a valgus positioning.When a child falls on the outstrechted arm, this can lead to extreme valgus.On the lateral side this can result in a dislocation or a fracture of the radius with or without involvement of the olecranon.When the forces have more effect on the humerus, the extreme valgus will result in a fracture of the lateral condyle.On the medial side the valgus force can lead to avulsion of the medial epicondyle.Sometimes the medial epicondyl becomes trapped within the joint.Because of the valgus position of the normal elbow an avulsion of the lateral epicondyle will be uncommon.,Extreme valgus,The other important fracture mechanism is extreme valgus of the elbow.The normal elbow already has a valgus positioning.When a child falls on the outstrechted arm, this can lead to extreme valgus.On the lateral side this can result in a dislocation or a fracture of the radius with or without involvement of the olecranon.When the forces have more effect on the humerus, the extreme valgus will result in a fracture of the lateral condyle.On the medial side the valgus force can lead to avulsion of the medial epicondyle.Sometimes the medial epicondyl becomes trapped within the joint.Because of the valgus position of the normal elbow an avulsion of the lateral epicondyle will be uncommon.,When looking at radiographs of the elbow after trauma a methodical review of the radiographs is needed .You should ask yourself the following important questions.Is there a sign of joint effusion?After trauma this almost always indicates the presence of hemarthros due to a fracture (either visible or occult).Is there a normal alignment between the bones?In children dislocations are frequent and can be very subtle.Are the ossification centres normal?Is the piece of bone that youre looking at a normal ossification centre and is this ossification centre in the normal position. .Look especially for the position of the radial epiphysis and the medial epicondyle (figure).Is there a subtle fracture?Some of the fractures in children are very subtle.So you need to be familiar with the typical picture of these fractures. .,Alignment,There are two important lines which help in the diagnosis of dislocation and fracture .These are the Radiocapitellar line and the Anterior humeral line.Radiocapitellar lineA line drawn through the centre of the radial neck should pass throught the centre of the capitellum, whatever the positioning of the patient, since the radius articulates with the capitellum (figure).In dislocation of the radius this line will not pass through the centre of the capitellum.On the left we see, that the radiocapitellar line goes through centre of the capitellum on every radiogragh even though C and D are not well positioned.Notice supracondylar fracture in B.,Radiographs of elbows at different ages. The Anterior Humeral line goes through the middle third of the capitellum,On the left the anterior humeral line passes through the anterior third of the capitellum.This indicates that the condyles are displaced dorsally (i.e. supracondylar fracture).,Ossification centres,There are 6 ossification centres around the elbow joint.They appear and fuse to the adjacent bones at different ages.It is important to know the sequence of appearance since the ossification centers always appear in a strict order.This order of appearance is specified in the mnemonicC-R-I-T-O-E(Capitellum - Radius - Internal or medial epicondyle - Trochlea - Olecranon - External or lateral epicondyle).The ages at which these ossification centres appear are highly variable and differ between individuals.It is not important to know these ages, but as a general guide you could remember 1-3-5-7-9-11 years.,The order of appearance of the ossification centres is specified in the mnemonic C-R-I-T-O-E.,Supracondylar fractures,Supracondylar fractures. In A the anterior humeral line passes through the anterior third of the capitellum and in B even more anteriorly. Notice positive posterior fat pad sign in both case,Lateral Condyle fractures,This fracture is the second most common distal humerus fracture in children.They occur between the ages of 4 and 10 years.These fractures occur when a varus force is applied to the extended elbow.They tend to be unstable and become displaced because of the pull of the forearm extensors.Since these fractures are intra-articular they are prone to nonunion because the fracture is bathed in synovial fluid.Lateral condyle fractures are classified according to Milch. They are Salter-Harris IV epiphysiolysis fractures.Most are Milch