fracture-dislocation is present when a joint has dislocated and there is in addition a fracture of one of the bony components of the joint. Illustrated is a fracture-dislocation of the shoulder, where there is an anterior dislocation with a fracture of the neck of the humerus. Injuries of this kind may be difficult to reduce and may be unstable. Stiffness and avascular necrosis arc two common complications.
33. Fractures involving the articular surfaces of a joint: In partial articular fractures (1) part of the joint surface is involved, but the remainder is intact and solidly connected to the rest of the bone (AO Type B fracture). In complete articular fractures (2) the articular surface is completely disrupted and separated from the shaft (AO Type C fracture). When a fracture involves the articular surfaces, any persisting irregularity may cause secondary osteoarthritis (3). Stiffness is a common complication: this may be minimised by early mobilisation.
36. Complicated fractures: A fracture is described as complicated if there is accompanying damage to major neighbouring structures. The diagram is of a complicated supracondylar fracture of the humerus. (Such an injury might also be described as a supracondylar fracture complicated by damage to the brachial artery.)
37. Describing the level of a fracture
(a): The anatomical divisions of a long bone include (he epiphysis (E). epiphyseal plate (EP), and diaphysis or shall (D). Belween the latter two is the metaphysis (M). A fracture may be described as lying within these divisions, or involving a distinct anatomical part. e.g. A = fracture of the tibial diaphysis; B = fracture of the femoral neck; C = fracture of the greater trochanter; F = supracondylar fracture of the femur.
(b): For descriptive purposes a bone may be divided arbitrarily into thirds. In this way, A = fracture of the mid third of the femur; B = fracture of the femur in the distal third; C = fracture of the femur at the junction of the middle and distal thirds. The level of a fracture in some cases may be made quite clear by an eponym. e.g. a Colics fracture (I)) involves the radius, and occurs within an inch (2.5 cm) of the wrist.
(c): In AO terminology, long bones are divided into three unequal segments: a proximal segment (I). a central diaphyseal segment (2), and a distal segment (3). The boundaries belween these segments arc obtained by erecting squares (S) which accommodate the widest part of the bone ends. In the special case of the femur the diaphysis is described as commencing at the distal border of the lesser trochanter.
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