Biomechanical Comparison of Fixation Devices for First Metatarsocuneiform Joint Arthrodesis.

Unlabelled: Common surgical treatment of first tarsal-metatarsal arthritis is by first metatarsocuneiform joint arthrodesis. While crossed-screw and locking plate fixation are the most widely used methods, a novel construct was designed to alleviate soft tissue irritation while still providing stable fixation. Using anatomic first metatarsal and medial cuneiform composites, we compared 3 arthrodesis implants (crossed-screw, dorsal locking plate, and IO Fix) under 2 cyclic bending loading scenarios (cantilever and 4-point bending).

Distal fibula fracture fixation: Biomechanical evaluation of three different fixation implants.

Background: The goal of this study was to evaluate the biomechanical performance of three distal fibula fracture fixation implants in a matched pair cadaveric fibula model: (1) a 5-hole compression plate with lag screw, (2) a 5-hole locking plate with lag screw, and (3) the 6-hole tabbed-plate with locking screws.

Methods: Three-dimensional motions between the proximal and distal fibular segments were measured under cyclic valgus bending, cyclic compressive axial loading, and cyclic torsional external-rotation loading. During loading, strains were measured on the surfaces of each fibula near the simulated fracture site, and on the plate, to assess load transfer.

Periprosthetic femoral bone loss in total hip arthroplasty: systematic analysis of the effect of stem design.

Introduction: Periprosthetic bone loss may lead to major complications in total hip arthroplasty (THA), including loosening, migration, and even fracture. This study analysed the influence of femoral implant designs on periprosthetic bone mineral density (BMD) after THA.

Methods: The results of all previous published studies reporting periprosthetic femoral BMD following THA were compiled.

Static and dynamic fatigue behavior of topology designed and conventional 3D printed bioresorbable PCL cervical interbody fusion devices.

Recently, as an alternative to metal spinal fusion cages, 3D printed bioresorbable materials have been explored; however, the static and fatigue properties of these novel cages are not well known. Unfortunately, current ASTM testing standards used to determine these properties were designed prior to the advent of bioresorbable materials for cages. Therefore, the applicability of these standards for bioresorbable materials is unknown.

Biomechanical comparison of syndesmotic injury fixation methods using a cadaveric model.

Background: There is growing interest in suture-button devices for syndesmosis injury, which are intended to offer less rigid fixation than screw fixation.

Methods: The fixation strength with 2 different suture-button devices, ZipTight and TightRope, were compared using 5 cadaveric leg pairs (n = 10). In an additional 5 pairs (n = 10), ZipTight was compared to 3.

Fixation of non-cemented total hip arthroplasty femoral components in a simulated proximal bone defect model.

An accelerated sequential proximal femoral bone loss model was used to measure the initial stability of three noncemented femoral stem designs: fully porous-coated, proximally porous-coated, and dual-tapered, diaphyseal press-fit (N=18). Only dual-tapered, diaphyseal press-fit stems remained stable with as much as 105 mm of bone loss, with average cyclic micromotion remaining below 25 μm in ML and below 10 μm in AP planes. In contrast, with proximally coated and fully coated stem designs with circular or oval cross-sections, 60mm of bone loss, resulting in lower than 10 cm of diaphyseal bone contact length, led to gross instability, increasing average cyclic micromotions to greater than 100 μm prior to failure.

Biomechanical testing of pin configurations in supracondylar humeral fractures: the effect of medial column comminution.

Objectives: We measured biomechanical stability in simulated supracondylar humeral fractures fixed with each of 6 pin configurations, 2 with associated medial comminution, and developed a technique for reproducible pin placement and divergence.

Methods: A transverse supracondylar osteotomy was performed on 36 biomechanical humerus models. Of these, 24 (4 groups of 6 specimens each) were fixed with pins in 1 of 4 lateral entry configurations.