The swelling appears earlier and is more definite in superficial bones such as the tibia, than in those more deeply placed such as the upper end of the femur.  It may be less evident to the eye than to the fingers, and is best appreciated by gently stroking the bone from the middle of its shaft towards the end.  The maximum thickening and tenderness usually correspond to the junction of the diaphysis with the epiphysis, and the swelling tails off gradually along the shaft.  As time goes on there is redness of the skin, especially over a superficial bone, such as the tibia, the swelling becomes softer, and gives evidence of fluctuation.  This stage may be reached at the end of twenty-four hours, or not for some days.

Suppuration spreads towards the surface, until, some days later, the skin sloughs and pus escapes, after which the fever usually remits and the pain and other symptoms are relieved.  The pus may contain blood and droplets of fat derived from the marrow, and in some cases minute particles of bone are present also.  The presence of fat and bony particles in the pus confirms the medullary origin of the suppuration.

If an incision is made, the periosteum is found to be raised from the bone; the extent of the bare bone will be found to correspond fairly accurately with the extent of the lesion in the marrow.

Local Complications.—­The adjacent joint may exhibit symptoms which vary from those of a simple effusion to those of a purulent arthritis.  The joint symptoms may count for little in the clinical picture, or, as in the case of the hip, may so predominate as to overshadow those of the bone lesion from which they originated.

Separation and displacement of the epiphysis usually reveals itself by an alteration in the attitude of the limb; it is nearly always associated with suppuration in the adjacent joint.

When pathological fracture of the shaft occurs, as it may do, from some muscular effort or strain, it is attended with the usual signs of fracture.

Dislocation of the adjacent joint has been chiefly observed at the hip; it may result from effusion into the joint and stretching of the ligaments, or may be the sequel of a purulent arthritis; the signs of dislocation are not so obvious as might be expected, but it is attended with an alteration in the attitude of the limb, and the displacement of the head of the bone is readily shown in a skiagram.

General Complications.—­In some cases a multiplicity of lesions in the bones and joints imparts to the disease the features of pyaemia.  The occurrence of endocarditis, as indicated by alterations in the heart sounds and the development of murmurs, may cause widespread infective embolism, and metastatic suppurations in the kidneys, heart-wall, and lungs, as well as in other bones and joints than those primarily affected.  The secondary suppurations are liable to be overlooked unless sought for, as they are rarely attended with much pain.