Rapid prototyping technique in the preoperative planning for total hip arthroplasty with custom femoral components

One of the problems we come across in our practice is related to the patients with very disturbed anatomy structures of the hip joint due to the incompatibilities between standard implants and host bone. These incompatibilities are usually represented by an extreme narrowing of the femoral medullary canal or sometimes by disturbances of the diaphyseal anatomical axis of the femur and are encountered in younger patients who usually require pressfit uncemented implants in order to achieve a normal survivorship of the implant. In these particular cases, customized prosthetic components may represent an alternative, but there are still controversies regarding the biomechanical behavior of these implants compared to the standard components. The use of prototypes for the receiving bone and for the prosthetic implant, respectively, is helpful in the validation process of the optimal model of custom implant by eliminating those designs that cannot be inserted into the medullar canal or those that could injure the receiving bone structure. Prototype design and execution for both the implant and femoral structure by means of rapid prototyping technology represents a major advantage in carrying out the preoperative planning of this type of surgical interventions due to the possibility of preoperative simulation of the insertion of femoral component into the medullar canal.