The primary stability of pelvic reconstruction after partial supraacetabular pelvic resection due to malignant tumours of the human pelvis: A biomechanical in vitro study

Computer Navigation and 3D Printing in the Surgical Management of Bone Sarcoma

The long-term outcomes of osteosarcoma have improved; however, patients with metastases, recurrence or axial disease continue to have a poor prognosis. Computer navigation in surgery is becoming ever more commonplace, and the proposed advantages, including precision during surgery, is particularly applicable to the field of orthopaedic oncology and challenging areas such as the axial skeleton. Within this article, we provide an overview of the field of computer navigation and computer-assisted tumour surgery (CATS), in particular its relevance to the surgical management of osteosarcoma.

Pelvic reconstruction with different rod-screw systems following Enneking type I/I + IV resection: a clinical study

The mechanical outcomes of patients with pelvic bone tumors involving zone I or zone I + IV who received resection and different reconstructions are not clear. Therefore, the purpose of this study was to compare the outcomes of different rod-screw systems in reconstruction for these patients, and evaluate the relative risk of mechanical failure for them. We reviewed 30 patients for a mean duration of 40.4 months of follow-up (range, 13.1–162.2 months), five patients had mechanical complications. The mechanical survival rate of two-rod and four-screw (TRFS) group was significantly higher than one-rod and two-screw (ORTS) group (p = 0.000). The implant survival rate was correlated with ages (p = 0.010), younger people are more likely to fail. Thus, TRFS fixation for pelvic reconstruction after Enneking type I/I + IV resection can provide better short to long-term mechanical stability compared with ORTS fixation, the strength of ORTS fixation is not enough. In addition, biological reconstruction such as autologous bone graft is recommended for the patients who are younger or suffered from benign tumor. As for the patients who are older, with malignant tumors, underwent adjuvant radiotherapy or chemotherapy, functional reconstruction with bone cement is a good choice.

Biomechanical study of different fixation techniques for the treatment of sacroiliac joint injuries using finite element analyses and biomechanical tests

The pelvis is one of the most stressed areas of the human musculoskeletal system due to the transfer of truncal loads to the lower extremities. Sacroiliac joint injury may lead to abnormal joint mechanics and an unstable pelvis. Various fixation techniques have been evaluated and discussed. However, it may be difficult to investigate each technique due to variations in bone quality, bone anatomy, fracture pattern, and fixation location. Additionally, the finite element method is one useful technology that avoids these variations. Unfortunately, most previous studies neglected the effects of the lumbar spine and femurs when they investigated the biomechanics of pelvises. Thus, the aim of this study was to investigate the biomechanical performance of intact, injured, and treated pelvises using numerical and experimental approaches. Three-dimensional finite element models of the spine-pelvis-femur complex with and without muscles and ligaments were developed. The intact pelvis, the pelvis with sacroiliac joint injury, and three types of pelvic fixation techniques were analyzed. Concurrently, biomechanical tests were conducted to validate the numerical outcomes using artificial pelvises. Posterior iliosacral screw fixation showed relatively better fixation stability and lower risks of implant failure and pelvic breakage than sacral bar fixation and a locking compression plate fixation. The present study can help surgeons and engineers understand the biomechanics of intact, injured, and treated pelvises. Both the simulation technique and the experimental setup can be applied to investigate different pelvic injuries.

Mechanical comparison of iliosacral reconstruction techniques after sarcoma resection

BACKGROUND

Reconstruction of iliosacral defects following oncologic resection is a difficult clinical problem associated with a high incidence of failure. Technical approaches to this problem are heterogeneous and evidence supporting specific techniques is sparse. Maximizing construct stability may improve union rates and functional outcomes. The purpose of this study is to compare construct stiffness, load to failure, and mechanism of failure between two methods of iliosacral reconstruction in an ex-vivo model to determine if either is mechanically superior.

METHODS

Eight third-generation composite pelves reconstructed with a plate-and-screw technique were tested against seven pelves reconstructed with a minimal spinal instrumentation technique using axial loading in a double-leg stance model.

FINDINGS

The pelves from the plate group demonstrated higher stiffness in the direction of applied load (102.9 vs. 66.8N/mm; p=0.010) and endured a significantly larger maximum force (1416 vs. 1059N; p=0.015) than the rod group prior to failure. Subjectively, the rod-reconstructed pelves were noted to be rotationally unconstrained while pivoting around their single point-of fixation in each segment leading to earlier failure.

INTERPRETATION

Plate-reconstruction was mechanically superior to spinal instrumentation in the manner performed in this study. More than one point of fixation in each segment should be achieved to minimize the risk of rotational deformation.