Cement-augmented screw fixation for calcaneal fracture treatment: a biomechanical study comparing two injectable bone substitutes

Antibiotic-loaded bone cement fixation technique combined with bilateral pectoralis major muscle flaps tension-free management for sternal infection after midline sternotomy

INTRODUCTION

Deep sternal wound infection (DSWI) after midline sternotomy of cardiac surgery is a challenging complication that affects the outcome of surgery. This study aims to assess the clinical effectiveness of the antibiotic-loaded bone cement fixation technique combined with bilateral pectoralis major muscle flaps tension-free management in the treatment of DSWI.

METHODS

We retrospectively analyzed 5 patients with DSWI who underwent antibiotic-loaded bone cement combined with bilateral pectoralis major muscle flaps for chest wall reconstruction after sternotomy for cardiac surgery in a tertiary hospital in China from January 2020 to December 2021. The clinical and follow-up data were retrospectively analyzed.

RESULTS

All patients had no perioperative mortalities, no postoperative complications, 100% wound healing, and an average hospital stay length of 24 days. The follow-up periods were from 6 to 35 months (mean 19.6 months). None of the cases showed wound problems after initial reconstruction using antibiotic-loaded bone cement combined with bilateral pectoralis major muscle flaps.

CONCLUSIONS

We report our successful treatment of DSWI, using antibiotic-loaded bone cement fixation technique combined with bilateral pectoralis major muscle flaps tension-free management. The clinical and follow-up results are favorable.

Development of Poly(methyl methacrylate)/nano-hydroxyapatite (PMMA/nHA) Nanofibers for Tissue Engineering Regeneration Using an Electrospinning Technique

The study explores the in vitro biocompatibility and osteoconductivity of poly(methyl methacrylate)/nano-hydroxyapatite (PMMA/nHA) composite nanofibrous scaffolds for bone tissue engineering (BTE). Electrospun scaffolds, exhibiting both low and high fiber orientation, were investigated. The inclusion of hydroxyapatite nanoparticles enhances the osteoconductivity of the scaffolds while maintaining the ease of fabrication through electrospinning. SEM analysis confirms the high-quality morphology of the scaffolds, with successful incorporation of nHA evidenced by SEM-EDS and FTIR methods. DSC analysis indicates that nHA addition increases the PMMA glass transition temperature (Tg) and reduces stress relaxation during electrospinning. Furthermore, higher fiber orientation affects PMMA Tg and stress relaxation differently. Biological studies demonstrate the composite material's non-toxicity, excellent osteoblast viability, attachment, spreading, and proliferation. Overall, PMMA/nHA composite scaffolds show promise for BTE applications.

Treatment of Metaphyseal Defects in Plated Proximal Humerus Fractures with a New Augmentation Technique-A Biomechanical Cadaveric Study

Background and Objectives: Unstable proximal humerus fractures (PHFs) with metaphyseal defects-weakening the osteosynthesis construct-are challenging to treat. A new augmentation technique of plated complex PHFs with metaphyseal defects was recently introduced in the clinical practice. This biomechanical study aimed to analyze the stability of plated unstable PHFs augmented via implementation of this technique versus no augmentation. Materials and Methods: Three-part AO/OTA 11-B1.1 unstable PHFs with metaphyseal defects were created in sixteen paired human cadaveric humeri (average donor age 76 years, range 66-92 years), pairwise assigned to two groups for locked plate fixation with identical implant configuration. In one of the groups, six-milliliter polymethylmethacrylate bone cement with medium viscosity (seven minutes after mixing) was placed manually through the lateral window in the defect of the humerus head after its anatomical reduction to the shaft and prior to the anatomical reduction of the greater tuberosity fragment. All specimens were tested biomechanically in a 25° adduction, applying progressively increasing cyclic loading at 2 Hz until failure. Interfragmentary movements were monitored by motion tracking and X-ray imaging. Results: Initial stiffness was not significantly different between the groups, p = 0.467. Varus deformation of the humerus head fragment, fracture displacement at the medial humerus head aspect, and proximal screw migration and cut-out were significantly smaller in the augmented group after 2000, 4000, 6000, 8000 and 10,000 cycles, p ≤ 0.019. Cycles to 5° varus deformation of the humerus head fragment-set as a clinically relevant failure criterion-and failure load were significantly higher in the augmented group, p = 0.018. Conclusions: From a biomechanical standpoint, augmentation with polymethylmethacrylate bone cement placed in the metaphyseal humerus head defect of plated unstable PHFs considerably enhances fixation stability and can reduce the risk of postoperative complications.

Surgical Fixation of Calcaneal Beak Fractures—Biomechanical Analysis of Different Osteosynthesis Techniques

The calcaneal beak fracture is a rare avulsion fracture of the tuber calcanei characterized by a solid bony fragment at the Achilles tendon insertion. Treatment usually requires osteosynthesis. However, lack of biomechanical understanding of the ideal fixation technique persists. A beak fracture was simulated in synthetic bones and assigned to five different groups of fixation: A) 6.5-mm partial threaded cannulated screws, B) 4.0-mm partial threaded cannulated screws, C) 5.0-mm headless cannulated compression screws, D) 2.3-mm locking plate, and E) 2.8-mm locking plate. Different traction force levels were applied through an Achilles tendon surrogate in a material-testing machine on all stabilized synthetic bones. Outcome measures were peak-to-peak displacement, total displacement, plastic deformation, stiffness, visual-fracture-line displacement, and mode of implant failure. The 2.3- and 2.8-mm plating groups showed a high drop-out rate at 100 N tension force and failed under higher tension levels of 200 N. The fracture fixation using 4.0-mm partial threaded screws showed a significantly higher repair strength and was able to withhold cyclic loading up to 300 N. The lowest peak-to-peak displacement and the highest load-to-failure and stiffness were provided by fracture fixation using 6.5-mm partial threaded cannulated screws or 5.0-mm headless cannulated compression screws. As anticipated, large 6.5-mm screw diameters provide the best biomechanical fixation. Surprisingly, the 5.0-mm headless cannulated compression screws yield reliable stability despite the absent screw head and washer. When such large screws cannot be applied, 4.0-mm screws also allow reasonable fixation strength. Plate fixation should be implemented with precaution and in combination with a restrictive postoperative motion protocol. Finally, clinical cases about the surgical application and recovery are included.

Bone Tissue Engineering in the Treatment of Bone Defects

Bones play an important role in maintaining exercise and protecting organs. Bone defect, as a common orthopedic disease in clinics, can cause tremendous damage with long treatment cycles. Therefore, the treatment of bone defect remains as one of the main challenges in clinical practice. Today, with increased incidence of bone disease in the aging population, demand for bone repair material is high. At present, the method of clinical treatment for bone defects including non-invasive therapy and invasive therapy. Surgical treatment is the most effective way to treat bone defects, such as using bone grafts, Masquelet technique, Ilizarov technique etc. In recent years, the rapid development of tissue engineering technology provides a new treatment strategy for bone repair. This review paper introduces the current situation and challenges of clinical treatment of bone defect repair in detail. The advantages and disadvantages of bone tissue engineering scaffolds are comprehensively discussed from the aspect of material, preparation technology, and function of bone tissue engineering scaffolds. This paper also summarizes the 3D printing technology based on computer technology, aiming at designing personalized artificial scaffolds that can accurately fit bone defects.