This invention relates to orthopedic cerclage devices for use in stabilizing fractured bones. Cerclage devices, in the form of plastic or metal straps, bracing devices, wires or bands have been proposed and used to secure together and stabilize the segments of a fractured bone. The cerclage technique has advantages over more conventional techniques for stabilizing fractured bones such as skeletal traction. Skeletal traction typically requires the patient to remain in bed for a long time, often in excess of three to four months. Such prolonged period of immobilization is undesirable and can be particularly hazardous for elderly patients. Thus, there has been a need for an effective cerclage device which can avoid, or at least reduce, the requirement for skeletal traction. Although a number of cerclage devices have been proposed in recent years, and while some of them have had a limited degree of use, they have presented a number of difficulties which have detracted from their use.
For example, the earlier cerclage devices, such as the Parham steel band, were little more than wires or metal straps wrapped and secured tightly about the bone segments. In order for the Parham band to grip bone segments sufficiently tightly to stabilize them, the band would tend to be so tight about the bone as to cut off substantial portions of the vascular circulation within the bone. Cutting off circulation in the bone eventually leads to death of the affected parts of the bone and possibly the entire bone. Thus, in most instances where a Parham band or similar constricting wire has been used it was usually necessary to remove the band or wire within a number of weeks after the initial placement. That, of course, subjects the patient to a second operation with its inherent risks and complications.
In an effort to avoid the difficulties caused by the Parham steel band other cerclage devices have been proposed. One such device is described in U.S. Pat. No. 4,119,091. It is in the form of a nylon strap having small projections on its undersurface to hold the strap away from the bone. The object of the nylon device is to reduce the area of contact with the bone so as to reduce the constricting effect on the bone vascularization. That device, however, may not provide sufficient stability for the fractured bone segments. An additional difficulty presented by the prior devices which remained implanted in the patient is that as the bone heals the pressure of the device may inhibit the quality and size of the callus which forms around the region of the fracture and could affect the strength of the bone when it is healed.
Another desirable characteristic of a cerclage device is that it should be easily manipulated, placed and handled by the surgeon. The devices which have been proposed in the prior art typically have been formed from a stiff material such as metal or plastic and have had less than ideal handling characteristics.
Thus, a need has existed for an improved cerclage device for securing and stabilizing fractured bone segments. It is among the primary objects of the invention to provide such a cerclage device.