The present invention relates to an implantable constriction device for constricting the urethra, urine bladder, anus, colon or rectum of an incontinent patient.
This kind of constriction device, in the form of a banding device in which a band encircles and adjustably constricts a portion of a patient's urethra, urine bladder, anus, colon or rectum, has been used in surgery for treating anal and urinary incontinence. In practice, the band is made of silicone, which is a material approved and widely used for implantation. Moreover, the silicone band has an acceptable tensile strength and is fairly resistant to aggressive body fluids. Where the band is hydraulically adjusted, the hydraulic fluid used typically is an isotonic salt solution mixed with other conventional materials.
A problem with traditional silicone bands, however, is that the silicone material gives the band certain inadequate properties, such as poor fatigue resistance and poor endurance of static bending forces, which over time might result in breakage of the band. Furthermore, silicone is a material that is semi-permeable by liquid, which is a drawback to hydraulic silicone bands, because hydraulic fluid can escape by diffusing through the silicone material. As a result, accurate adjustments of a hydraulic band are difficult to perform because of the loss of hydraulic fluid and the need for the patient to regularly visit a doctor to add hydraulic fluid to and calibrate the constriction device. These inadequate properties are serious, considering that the band is implanted for the rest of the patient's life. Another problem is that the band somewhat restrains the dynamic movements of adjacent organs necessary for the transportation of urine or fecal matter. As a consequence, the band might erode, and over time injure the urethra, urine bladder, anus, colon or rectum.