Repair of Periprosthetic Pelvis Defects With Porous Metal Implants: A Finite Element Study

Abstract

Periacetabular osteolysis is a potentially difficult surgical challenge, which can often drive the choice of reconstruction methods used in revision hip replacement. For smaller defects, impaction of bone grafts may be sufficient, but larger defects can require filler materials that provide structural support in addition to filling a void. This study utilized finite element analysis (FEA) to examine the state of stress in periprosthetic pelvic bone when subjected to a stair-climbing load and in the presence of two simulated defects, to show the effect of implanting a defect repair implant fabricated from Trabecular Metal. Even a small medial bone defect showed a local stress elevation of 4x compared with that seen with an acetabular implant supported by intact periacetabular bone. Local bone stress was much greater (8x the baseline level) for a defect case in which the loss of bone superior to the acetabular implant permitted significant migration. FEA results showed that a repair of the small defect with a Trabecular Metal restrictor lowered periprosthetic bone stress to a level comparable to that in the case of a primary implant. For the larger defect case, the use of a Trabecular Metal augment provides structural stabilization and helps to restore the THR head center. However, stress in the adjacent periprosthetic bone is lower than that observed in the defect-free acetabulum. In the augment case, the load path between the femoral head and the pelvis now passes through the augment as the superior rim of the acetabulum has been replaced. Contact-induced stress in the augment is similar in magnitude to that seen in the superior rim of the baseline case, although the stress pattern in the augment is noticeably different from that in intact bone.

Intracavitary and Extracavitary Iliac Extended Fixation Using Porous Metal Augments for Paprosky Type 3 Acetabular Defects in Revision Total Hip Arthroplasty: A Minimum 2 Years Follow-up

“…According to the Paprosky classification system, the superior aspect of the acetabulum comprises an important part of the bone defect pattern. Biomechanical studies have revealed that the superior bone serves as the major support structure for acetabular cups and an essential component in the process of transmitting load from the hip to the sacroiliac joint [12,19,23], and superior and lateral migration of the COR significantly increases joint reaction force, risk of loosening, and decreased range of motion [4,17,18,21,24,35,37]. In knee revision procedures, Haddad et al proposed the concept of zone fixation in the metaphysis and diaphysis, while preserving the knee joint line level [12,22].…”

“…Any discrepancies between the two surgeons were re-examined by the senior consultant surgeon (YXZ). There were 13 (40.6%) patients classified as Paprosky type 3A, 19 (59.4%) as type 3B. Five (15.6%) of the type 3B patients were assessed to have pelvic discontinuity.…”

Customized Knee Prosthesis in Treatment of Giant Cell Tumors of the Proximal Tibia: Application of 3-Dimensional Printing Technology in Surgical Design

“…This kind of technique has been safely applied in some prosthesis revision systems [25,26]. The interfaces between the tibial tray and 3D-printed Ti-alloy were filled by bone cement, reducing the chance of fatigue and corrosion.…”

Finite element analysis of the pelvis after modular hemipelvic endoprosthesis reconstruction

“…Finite element (FE) analysis, which can accommodate large inter-subject variations in bone geometry and material properties, has been widely used to analyse pelvic biomechanics [15][16][17][18][19]. An empirically validated FE model can provide information on the static and dynamic responses of joint structures under a variety of loading and boundary conditions that would be difficult or impossible to obtain experimentally [20][21][22].…”