+Supports.+ Flexible supports may be made of boiler felt; one objection to these is their liability to stretch. They are of service in young children, in mild cases, and in convalescent cases where it is desirable to have the patient use a flexible instead of a stiff support in order to bring the muscles into play. Rigid supports are best made of tempered spring steel (18 to 20 gage), forged hot to fit a cast of the foot. They may also be made of phosphor-bronz, celluloid or aluminum. The shape of the plate is largely a matter of judgment. The easiest way to determine the shape of the plate to be used in a given case is to have the patient stand with the operator’s hand under the inner side of the foot; the operator then places the foot in the normal position and notes where the pressure must be applied to secure the proper correction; when the anterior part of the foot is flattened, a slight dome must be constructed in the front of the plate; when the os calcis is clearly tilted over, the plate must have two flanges at the heel to hold it in place. In general, the plate must reach forward to a point just behind the great-toe joint, and must furnish support as far as the front of the heel. The plate should be higher on the inner side, and a flange formation is generally necessary to accomplish this. An outer flange prevents the foot from slipping off the outer side of the plate. When the foot no longer requires support, the plate should be gradually discontinued. The “Thomas” sole may be used in mild cases. This is made by building up the inner part of the sole of the shoe one-eighth to one-quarter of an inch higher than the outer side, thus securing a slight inversion of the foot. Exercise and massage of the deficient muscles should form a part of the routine treatment in all cases of flexible flat foot. To diminish local inflammation and irritability, the foot should be soaked in hot water; hot and cold alternate douches should be applied, and hot-air treatment and massage should be employed. +Rigid Flat Foot.+ Rigid flat foot cannot be successfully treated until the position of the foot is corrected. The patient should be anesthetized, and, by the use of a wedge as a fulcrum, the bones should be forced into position. A pressure of about two hundred pounds is generally necessary to effect this reduction. After this, the foot is placed in a plaster cast, in extreme adduction and is allowed to remain thus encased for three weeks. After this, a properly fitted plate should be worn. The results are usually satisfactory. +Operative Treatment.+ Cases that have resisted all other forms of treatment, may be cured by the removal of a wedge-shaped piece of bone, with the base downward and inward at the point of greatest inward convexity, that is, in the neighborhood of the head of the astragalus. Osteotomy of the front of the os calcis and neck of the astragalus will at times be necessary for a radical cure.