Rush Pins were specifically designed to provide simplified, dynamic intramedullary fracture fixation with minimal trauma.
Every severe fracture has its characteristic deformity. It may be called a muscle pull or intrinsic dynamic force, but it is a deforming force. For good fixation this force must be overcome. The muscle pull of the extremity must be utilized to provide contact compression. It is for this reason that the Rush Pin came into being. It was designed to exert a dynamic force of its own to resist this deforming force. The design of the pin calls for introduction from the side of the bone, rarely from the end. The sled runner point drives through cancellous bone, deflects from the cortex, drives and guides easily, yet effectively locks the distal fragment against rotation. The Rush Pin must not impact the marrow cavity, but must lock the bone by points of pressure. The pin must be manufactured from a special metal with all characteristics required for proper resilience.
Be careful. Intramedullary pins can break!
Fracture of the pin, of proper size, in a normally healing bone is extremely unlikely if caution is exercised in the after care of the patient. When fixation of the fracture is stable, early active motion of the extremity can be permitted to prevent stiffness of the contiguous joints and to maintain normal circulation of the extremity and muscular tone.
Excessive weight bearing or excessive muscular activity before healing occurs can delay healing, precipitate non-union and cause stress fatigue in the pin at the fracture site with eventual fracture of the pin at this level. In the event of non-union, with persistent rocking at the fracture site fracture of the pin is inevitable! Frequent post-operative x-rays are necessary. The presence of the extension of the fracture line into the new forming peripheral callus is indicative of excessive weight bearing or motion at the fracture site. Pain at the fracture site on weight bearing also strongly suggests that this activity should be delayed. When in doubt SPLINT.
The after care of each patient must be individualized. Most simple fractures of the femur and tibia shafts can be fixed stably enough that external splinting is not necessary. Comminuted fractures and fractures near the knee joint might require a long leg cast or KES dressing. Our inclination, frequently, is to apply a long leg KES dressing in such cases, which is worn during the swelling period and when the sutures are removed, again assess the situation to decide whether further casting is indicated.
Weight bearing is begun gradually and increased as favorable cirumstances permit. The presence of the intramedullary pin in the bone gives some patients a sense of false security and they are prone to excessive activities which sometimes prove disastrous.
Pins should not be reused because of possible stress fatigue being present.