Is the magnesium screw as stable as the titanium screw in the fixation of first metatarsal distal chevron osteotomy? A comparative biomechanical study on sawbones models

Background: Distal chevron osteotomy (DCO) is commonly performed in hallux valgus surgery. The fixation of the osteotomy is provided by various implants. The usage of biodegradable implants such as magnesium is gradually increasing due to the advantages they provide. In this study, we aimed to compare the fixation of DCO with magnesium or titanium screw biomechanically. Methods: Twenty sawbones were used. The samples were divided into two equal groups, including ten sawbones for fixation with single headless titanium (group-1) or magnesium screw (group-2). DCO and screw fixations were performed on all samples using the same technique. Biomechanical testing was applied to five samples in each group in cantilever and the other five in a physiological configuration using a computer connected to the electromechanical test machine. The obtained data were evaluated using the Shapiro–Wilk test, Student’s t-test and Mann–Whitney U test on the IBM® SPSS (Statistical Package for the Social Sciences) V22.0 software. Significance was accepted at the p < 0.05 level. Results: There was no statistically significant difference between the magnesium screw and the titanium screw in terms of maximum force, maximum displacement and stiffness measurements in cantilever and physiological loadings ( p > 0.05 for all). Conclusion: This study found no significant difference in biomechanical stability between the magnesium and titanium screws in DCO fixation on sawbones. Further studies with real bones are needed.

Possibilidade de ossificação intracondral dirigida a partir de uma matriz óssea com titânio

In the present study, the relation between bone, cartilage and titanium was analyzed. According to the established methodology, homogeneous cartilage grafts conserved in alcohol 100 GL for 7 days were used, after the fixation of a homologous cartilage graft above the bone cortical of a rat femur (Rattus novergicus var. Albinus rodentia mammalia cepa Wistar), using a titanium screw implant. The animals were sacrificed at 10, 20, 30 and 60 days after surgery. To the histological examination, in hematoxillin and eosin sections, intrachondral bone neoformation could be observed since cortical surface, with possibility of complete substitution of the cartilage graft by bone, with similar volume and shape. In this experimental study we concluded that the homogeneous cartilage conserved can be used as graft not only for tissue substitution but also as an inductor of bone growth in rats.

Correction to: Biodegradable magnesium-based screw clinically equivalent to titanium screw in hallux valgus surgery: short term results of the first prospective, randomized, controlled clinical pilot study

An amendment to this paper has been published and can be accessed via the original article.

SIMULATION OF THE MECHANICAL STIMULATION EFFECT ON THE PEN JUNCTION BETWEEN BONE AND PELVIC BASED ON FINITE ELEMENT METHODS

Bone remodeling process influenced by cells osteoblast and osteoclast. The remodeling of cortical and trabecular influenced by mechanical stimuli. In this study, cortical and trabecular bones of 25 years old humans were observed, and the result was the cortical bone has the average Young’s modulo 17.9 MPa with the Poisson’s ratio of 0.4. Trabecular bone has the average Young’s modulo of 13 MPa and the Poisson’s ratio of 0.5. The metal orthopedic bone screw, which has used in this research simulation, was is a Titanium screw. The screw has Young’s modulo of 110 GPa and the Poisson’s ratio of 0.29. The results of the simulation of femoral bone elasticity limit with standing activity at the age of 25 were found in the left femur of 112.9416 MPa and the right femur of 115.5134 MPa. The limit of elasticity of the femur due to walking was found in the left femur of 115.2166 MPa with an accuracy of 94.11% and the right femur of 117.6692 MPa.

Are Magnesium Screws Proper for Mandibular Condyle Head Osteosynthesis?

Recently, magnesium alloys have gained a significant amount of recognition as potential biomaterials for degradable implants for craniofacial bone screws. Purpose: The aim of this work was to compare screws made specifically for mandibular head osteosynthesis from different materials. Materials and Methods: Screws measuring 14 mm made by one manufacturer specifically for mandibular head osteosynthesis out of the following materials were selected: magnesium (MgYREZr), titanium (Ti6Al7Nb), and polymer (PLGA). The axial pull-out strength and torsional properties were investigated. Results: Each type of screw presented different pull-out forces (Kruskal–Wallis test, p < 0.001). The magnesium screw had the highest pull-out force of 399 N (cracked without the screw out being pulled out), followed by the titanium screw, with a force of 340 N, and the PLGA screw, with a force of 138 N (always cracked at the base of the screw head without the screw being pulled out). ANOVA was performed for the maximal torques before damage to the screw (torsional properties), revealing that the maximal torque of the magnesium screw was 16 N·cm, while that of the titanium screw was 19 N·cm. The magnesium screw was significantly weaker than the titanium screw (p < 0.05). The measured torque and pull-out force were not related to each other (p > 0.05). Conclusion: Among the screws compared, the metal biodegradable magnesium screw seems to be the most suitable material for multiscrew mandibular head osteosynthesis, considering the condition of the fragile screwdriver socket.

Three-Dimensional Printed Porous Titanium Screw with Bioactive Surface Modification for Bone–Tendon Healing: A Rabbit Animal Model

The interference screw fixation method is used to secure a graft in the tibial tunnel during anterior cruciate ligament reconstruction surgery. However, several complications have been reported, such as biodegradable screw breakage, inflammatory or foreign body reaction, tunnel enlargement, and delayed graft healing. Using additive manufacturing (AM) technology, we developed a titanium alloy (Ti6Al4V) interference screw with chemically calcium phosphate surface modification technology to improve bone integration in the tibial tunnel. After chemical and heat treatment, the titanium screw formed a dense apatite layer on the metal surface in simulated body fluid. Twenty-seven New Zealand white rabbits were randomly divided into control and additive manufactured (AMD) screw groups. The long digital extensor tendon was detached and translated into a tibial plateau tunnel (diameter: 2.0 mm) and transfixed with an interference screw while the paw was in dorsiflexion. Biomechanical analyses, histological analyses, and an imaging study were performed at 1, 3, and 6 months. The biomechanical test showed that the ultimate pull-out load failure was significantly higher in the AMD screw group in all tested periods. Micro-computed tomography analyses revealed early woven bone formation in the AMD screw group at 1 and 3 months. In conclusion, AMD screws with bioactive surface modification improved bone ingrowth and enhanced biomechanical performance in a rabbit model.

Bioabsorbable Versus Titanium Screws in Anterior Cruciate Ligament Reconstruction Using Hamstring Autograft: A Prospective, Randomized Controlled Trial With 13-Year Follow-up

Background: Bioabsorbable screws for anterior cruciate ligament reconstruction (ACLR) have been a popular choice, with theoretical advantages in imaging and surgery. Titanium and poly-L-lactic acid with hydroxyapatite (PLLA-HA) screws have been compared, but with less than a decade of follow-up. Purpose/Hypothesis: The purpose was to compare long-term outcomes of hamstring autograft ACLR using either PLLA-HA screws or titanium screws. We hypothesized there would be no difference at 13 years in clinical scores or tunnel widening between PLLA-HA and titanium screw types, along with high-grade resorption and ossification of PLLA-HA screws. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: Forty patients undergoing ACLR were randomized to receive either a PLLA-HA screw or a titanium screw for ACL hamstring autograft fixation. Blinded evaluation was performed at 2, 5, and 13 years using the International Knee Documentation Committee score, Lysholm knee score, and KT-1000 arthrometer. Magnetic resonance imaging (MRI) was performed at 2 or 5 years and 13 years to evaluate tunnel volumes, ossification around the screw, graft integration, and cyst formation. Computed tomography (CT) of patients with PLLA-HA was performed at 13 years to evaluate tunnel volumes and intratunnel ossification. Results: No differences were seen in clinical outcomes at 2, 5, or 13 years between the 2 groups. At 13 years, tibial tunnel volumes were smaller for the PLLA-HA group (2.17 cm3) compared with the titanium group (3.33 cm3; P = .004). By 13 years, the PLLA-HA group had complete or nearly complete resorption on MRI or CT scan. Conclusion: Equivalent clinical results were found between PLLA-HA and titanium groups at 2, 5, and 13 years. Although PLLA-HA screws had complete or nearly complete resorption by 13 years, tunnel volumes remained largely unchanged, with minimal ossification.