A biomechanical comparison of steel screws versus PLLA and magnesium screws for the Latarjet procedure

Orthopaedic implant updates, in vitro study: Cytotoxicity comparison between stainless steel and magnesium implants

Background

Stainless steels are low-cost, biocompatible, and strong but it is not biodegradable. Therefore, implants from stainless steel to fixate bone fractures necessitate a second surgery for implant removal. Biodegradable implants have been widely researched to avoid second surgery for implant removal. However, the implant's safety (toxicity) when absorbed into the body has not been widely elicited.

Methods

This research was a true experimental study to compare 4 implants: Stainless Steel, Magnesium-Based, Magnesium with Plasma Electrolytic Oxidation (PEO) coating, and magnesium with poly lactic acid (PLA) composite with MTT Assay.

Results

Cells exposed to stainless steel implants have significantly less optical density (0.3546) than the magnesium implants group (0.4685; p < 0.05). In the cell viability test, 56.5 % of cells in stainless steel survived, which is lower than the magnesium implant group with 79.3 % of cells surviving (p < 0.05).

Conclusion

Magnesium implants were found to be significantly less toxic compared to stainless steel in this study. Amongst magnesium implants, magnesium with PEO coating was found to be the least toxic. However, further studies are required to ensure its safety in human usage.

Biomechanical Outcomes of Glenoid Bone Graft Fixation Techniques: A Systematic Review

BACKGROUND

The Latarjet and other bony augmentation procedures are commonly used to treat anterior shoulder instability in the setting of significant glenoid bone loss. Although several fixation strategies have been reported, the biomechanical strength of these techniques remains poorly understood.

PURPOSE

To perform a systematic review of the biomechanical strength of glenoid bony augmentation procedures for anterior shoulder instability.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic search of the Medline, Embase, Web of Science, and Cochrane Library databases was performed to identify biomechanical studies evaluating various fixation strategies for coracoid and other bone transfer procedures for anterior shoulder instability. Biomechanical results included load to failure with both compression and traction forces, stiffness, and cyclic displacement. The quality of included articles was assessed based on the Quality Appraisal for Cadaveric Studies (QUACS) scale.

RESULTS

A total of 21 biomechanical studies comprising 486 specimens were included. The number of screws used and the addition of washers were found to significantly increase rigidity and load to failure. The comparison of fixation techniques demonstrated mixed results in load to failure between screw and alternative constructs including suture buttons and suture anchors. However, studies that tested graft displacement consistently found more graft displacement in buttons compared with screws. The median and mean of the QUACS scale were both 12, with a range of 10-13.

CONCLUSION

Biomechanical studies consistently demonstrated that when glenoid bone grafts were fixed with screws, the number of screws and use of washers significantly increased construct rigidity and load to failure. Different metal screw materials and sizes did not consistently demonstrate a significant difference in biomechanical strength. There are mixed results when comparing suture buttons to screw fixation. The evaluated studies revealed that all double metal screw constructs and the majority of suture button and anchor constructs were able to withstand the glenohumeral load reflective of activities of daily living using a 150-N threshold.

Sutures, Screws, Buttons, and Anchors: A Review of Current Bone Graft Fixation Devices for Glenoid Bone Loss in the Unstable Shoulder

PURPOSE OF REVIEW

Anterior shoulder instability is associated with concomitant injury to several stabilizing structures of the shoulder, including glenoid bone loss. While instability is most common in young athletes and patients with predisposing conditions of hyperlaxity, recurrent shoulder instability can occur throughout various age ranges and may lead to longer term effects including pain and shoulder arthritis. Glenoid bone loss exceeding certain thresholds is generally treated by glenoid reconstruction via bone block augmentation to adequately stabilize the glenohumeral joint. These procedures increase the width of the articular surface on which the humeral head can translate before dislocation and, based on the procedure performed, provide a sling effect via the conjoined tendon, and increase tension to support the anterior capsule. The purpose of this review is to summarize the available literature regarding bone block fixation techniques.

RECENT DEVELOPMENTS

Various fixation techniques have been utilized to secure bone block transfers. Though screw fixation has traditionally been used for bone block fixation, suture buttons, suture anchors, and all-suture techniques have been utilized in attempts to avoid complications associated with the use of screws. Biomechanical studies report variable force-resistance, displacement, and mode of failure when comparing screw to suture button-based fixation of glenoid bone blocks. Clinical and radiographic studies have shown these novel suture-based techniques to be comparable, and in some cases advantageous, to traditional screw fixation techniques. While screw fixation has long been the standard of care in glenoid bone block procedures, it is associated with high complication rates, leading surgeons to endeavor toward new fixation techniques. In available biomechanical studies, screw fixation has consistently demonstrated high maximal load-to-failure and displacement with cyclic loading. Studies have reported similar clinical and radiographic outcomes in both screw and suture-based fixation methods, with evidence of reduced bone resorption with suture fixation. While suture button fixation is associated with a higher rate of recurrent instability, overall complication rates are low. Future research should address biomechanical shortcomings of suture-based fixation techniques and continue to assess long-term follow-up of patients treated with each fixation method.

Controversies in surgical management of anterior shoulder instability. State of the Art

Arthroscopic Bankart repair (ABR) has been accepted as a standard procedure for anterior shoulder instability with a minimum or no glenoid bone loss and an on-track Hill-Sachs lesion if present. However, several controversies exist in the surgical treatment of anterior shoulder instability. This article will discuss some of these controversies in, "simple," dislocations (without bone loss) as well as, "complex," (with critical bone loss). Determining which patients will benefit from an arthroscopic procedure depends on multiple factors including age, activity level, adequate determination of bone loss, performed with feasible and reliable imaging techniques. In the absence of concomitant significant bony and soft tissue pathology, ABR alone can provide satisfactory clinical results on a long-term basis. Controversies, including whether to remove cartilage from the edge of the glenoid, knotted versus knotless anchors, and routine rotator interval closure, still exist. In cases with significant bone loss, several bone restoring procedures have been described, such as, the Latarjet procedure, iliac crest bone graft, arthroscopic anatomic glenoid reconstruction with a frozen distal tibial allograft, and fresh distal tibial allograft reconstruction. This article will address these controversies and provide guidance based on available published data.

[Research progress of magnesium and magnesium alloy implants in sports medicine]

Objective

To review the research progress of magnesium and magnesium alloy implants in the repair and reconstruction of sports injury.

Methods

Relevant literature of magnesium and magnesium alloys for sports injury repair and reconstruction was extensively reviewed. The characteristics of magnesium and its alloys and their applications in the repair and reconstruction of sports injuries across various anatomical sites were thoroughly discussed and summarized.

Results

Magnesium and magnesium alloys have advantages in mechanical properties, biosafety, and promoting tendon-bone interface healing. Many preclinical studies on magnesium and magnesium alloy implants for repairing and reconstructing sports injuries have yielded promising results. However, successful clinical translation still requires addressing issues related to mechanical strength and degradation behavior, where alloying and surface treatments offer feasible solutions.

Conclusion

The clinical translation of magnesium and magnesium alloy implants for repairing and reconstructing sports injuries holds promise. Subsequent efforts should focus on optimizing the mechanical strength and degradation behavior of magnesium and magnesium alloy implants. Conducting larger-scale biocompatibility testing and developing novel magnesium-containing implants represent new directions for future research.

Absorbable implants in sport medicine and arthroscopic surgery: A narrative review of recent development

Over the past two decades, advances in arthroscopic and minimally invasive surgical techniques have led to significant growth in sports medicine surgery. Implants such as suture anchors, interference screws, and endo-buttons are commonly used in these procedures. However, traditional implants made of metal or inert materials are not absorbable, leading to complications that affect treatment outcomes. To address this issue, absorbable materials with excellent mechanical properties, good biocompatibility, and controlled degradation rates have been developed and applied in clinical practice. These materials include absorbable polymers, absorbable bioceramics, and absorbable metals. In this paper, we will provide a comprehensive summary of these absorbable materials from the perspective of clinicians, and discuss their clinical applications and related research in sport medicine.

High Complication Rate and High Percentage of Regressing Radiolucency in Magnesium Screw Fixation in 18 Consecutive Patients

(1) Background: Magnesium-based implants use has become a research focus in recent years. Radiolucent areas around inserted screws are still worrisome. The objective of this study was to investigate the first 18 patients treated using MAGNEZIX^® CS screws. (2) Methods: This retrospective case series included all 18 consecutive patients treated using MAGNEZIX^® CS screws at our Level-1 trauma center. Radiographs were taken at 3-, 6- and 9-month follow-ups. Osteolysis, radiolucency and material failure were assessed, as were infection and revision surgery. (3) Results: Most patients (61.1%) had surgery in the shoulder region. Radiolucency regressed from 55.6% at 3-month follow-ups to 11.1% at 9-month follow-ups. Material failure occurred in four patients (22.22%) and infection occurred in two patients, yielding a 33.33% complication rate. (4) Conclusion: MAGNEZIX^® CS screws demonstrated a high percentage of radiolucency that regressed and seems to be clinically irrelevant. The material failure rate and infection rate require further research.