#Snapping Hip# (_Hanche à ressort_).--This is a rare affection, met with in children and young adults, and characterised by the occurrence of a sudden, snapping sound, sometimes attended with pain in the region of the great trochanter. This usually occurs when the limb is slightly flexed or adducted, and rotated either inwards or outwards. On palpation a cord-like structure may be felt, which slips forwards and backwards over the trochanter when the position of the limb is altered. The condition was formerly described as a voluntary dislocation of the hip; it is now believed to be due to a cord-like band of tissue slipping backwards and forwards over the trochanter. The band is usually derived from the fascia lata, sometimes reinforced by the anterior fibres of the gluteus maximus, sometimes by the tensor fasciæ femoris. The condition seldom gives rise to any appreciable disability and surgical treatment is rarely called for. In a number of cases the muscle has been fixed by sutures with satisfactory results. In a recent case, an extensive open dissection proved negative, but the stitching of the gluteus to the trochanter was followed by the disappearance of the snapping. #Paralytic Deformities of the Hip.#--In anterior poliomyelitis the paralysis of muscles may be so widespread that the limb is unable to support the weight of the body, or certain groups of muscles only are paralysed and the child may be able to walk with the help of apparatus. Even if the ilio-psoas is paralysed, flexion is still possible by the anterior fibres of the gluteus medius, the anterior adductors, and when the leg is rotated out by the tensor fasciæ and sartorius, the dislocation differs from the traumatic variety in that the head, although it leaves the socket, remains within the capsule. Dislocation tends to occur from the disturbance of muscular balance, anterior dislocation being commoner than posterior in about the proportion of two to one; the nature of the dislocation is best demonstrated by means of the X-rays. Reduction is rarely possible without an open operation. Tendon and nerve-transplantation are scarcely possible, and arthrodesis is rarely to be recommended; contracture deformities, however, are often benefited by tenotomy in young children, and in older children by osteotomy through the trochanter, and putting the limb up in the abducted position. In _spastic paralysis_ of cerebral origin, the tendency is towards contracture, usually in the attitude of flexion, with adduction and inversion. This may result in dislocation backwards on to the dorsum ilii, and may occur in patients confined to bed (Fig. 131). [Illustration: FIG. 131.--Contracture Deformities of Upper and Lower Limbs resulting from Spastic Cerebral Palsy in infancy. (Photograph taken after death by Dr. Thomson of Norwich.)]