A fracture of the shaft of the humerus is perhaps the easiest of major long bones to treat by conservative methods. The humerus is a bone which generally unites quickly. If some shortening results it is of no significance. If some angular deformity persists it is usually concealed by muscle covering. If angular deformity persists it is concealed in the flexed position of the elbow and becomes revealed only when the elbow is fully extended (a position in which the elbow is rarely viewed in ordinary postures of the body). These are facts which must be remembered when any elaborate or operative method for treating this bone is under consideration.

Sling or Collar and Cuff

It is surprising how few people realise the fundamental difference in the mechanics of a sling and a ‘collar and cuff.’ Few realise that the two are diametrically opposite in their mechanical action on the humerus, shoulder, and shoulder girdle.

A sling elevates the point of the elbow and thus applies a vertical compression force in the length of the humerus and on the shoulder joint. It must not therefore be used when treating a fracture of the humerus because it will cause overriding and lateral angulation.

A collar and cuff allows the weight of the elbow to generate a traction force on the shoulder and it tends therefore to elongate the humerus.

When treating fractures of the humerus a collar and cuff must be used. When treating fractures of the clavicle and dislocation of the acromio-clavicular joint, where it is necessary to elevate the shoulder, a sling is required.