#Diagnosis of Hip Disease.#--The diagnosis is to be made not only from other affections of the joint, but also from morbid conditions in the vicinity of the hip, as in any of these the patient may seek advice on account of pain and a limp in walking. The patient should be stripped, and if able to walk, his gait should be observed. He is then examined lying on his back, and attention is directed to the comparative length of the limbs, to the attitude of the limbs and pelvis, and to the movements at the hip-joint, especially those of rotation. When there is any doubt as to the diagnosis, the examination should be repeated at intervals of a few days. In children, there are three non-febrile conditions attended with a limp and with shortening of the limb, which may be mistaken for hip disease,--_congenital dislocation_, _coxa vara_, and _paralysis following poliomyelitis_--but in all of these the movements are not nearly so restricted as they are in disease of the joint. In tuberculous disease of the _sacro-iliac joint_, while the pelvis may be tilted, and the limb apparently lengthened, the movements at the hip are retained. In tuberculous disease of the _great trochanter_, or of either of the _bursæ_ over it, while there may be abduction, eversion, impairment of mobility, and swelling in the region of the trochanter followed by abscess formation, the movements are less restricted than in disease of the joint. In _psoas abscess_ associated with spinal disease, or in _disease of the bursa underneath the psoas_, the limb is flexed and everted, there may be lordosis, and the patient may limp in walking, but the movements at the hip are restricted only in the directions of extension and inversion, while in hip disease they are restricted in all directions. _New-growths_ in the vicinity of the hip--especially central sarcoma of the upper end of the femur--are difficult to differentiate from hip disease without the help of the X-rays. Among other conditions which by interfering with the free mobility of the hip may simulate hip disease, are appendicitis, inflammation of the glands in the groin, staphylococcal disease of the upper end of the femur, and sciatica. The diagnosis _from other diseases of the hip-joint_ is made by careful consideration of the history, symptoms, and X-ray appearances. #Prognosis.#--The prognosis in hip disease is more serious than in tuberculosis of other joints, excepting only those of the spine, and it is most unfavourable when there are gross lesions of the bones and infected sinuses.