Biomimetic Composite Coatings for Activation of Titanium Implant Surfaces: Methodological Approach and In Vivo Enhanced Osseointegration

Innovative nanomaterials are required for the coatings of titanium (Ti) implants to ensure the activation of Ti surfaces for improved osseointegration, enhanced bone fracture healing and bone regeneration. This paper presents a systematic investigation of biomimetic composite (BC) coatings on Ti implant surfaces in a rat model of a diaphyseal femoral fracture. Methodological approaches of surface modification of the Ti implants via the usual joining methods (e.g., grit blasting and acid etching) and advanced physicochemical coating via a self-assembled dip-coating method were used. The biomimetic procedure used multi-substituted hydroxyapatite (ms-HAP) HAP-1.5wt%Mg-0.2wt%Zn-0.2wt%Si nanoparticles (NPs), which were functionalized using collagen type 1 molecules (COL), resulting in ms-HAP/COL (core/shell) NPs that were embedded into a polylactic acid (PLA) matrix and finally covered with COL layers, obtaining the ms-HAP/COL@PLA/COL composite. To assess the osseointegration issue, first, the thickness, surface morphology and roughness of the BC coating on the Ti implants were determined using AFM and SEM. The BC-coated Ti implants and uncoated Ti implants were then used in Wistar albino rats with a diaphyseal femoral fracture, both in the absence and the presence of high-frequency pulsed electromagnetic shortwave (HF-PESW) stimulation. This study was performed using a bone marker serum concentration and histological and computer tomography (micro-CT) analysis at 2 and 8 weeks after surgical implantation. The implant osseointegration was evaluated through the bone–implant contact (BIC). The bone–implant interface was investigated using FE-SEM images and EDX spectra of the retrieved surgical implants at 8 weeks in the four animal groups. The obtained results showed significantly higher bone–implants contact and bone volume per tissue volume, as well as a greater amount of newly formed bone, in the BC-coated Ti implants than in the uncoated Ti implants. Direct bone–implant contact was also confirmed via histological examination. The results of this study confirmed that these biomimetic composite coatings on Ti implants were essential for a significant enhancement of osseointegration of BC-coated Ti implants and bone regeneration. This research provides a novel strategy for the treatment of bone fractures with possible orthopedic applications.

Diaphyseal femoral fracture due to severe vitamin D3 deficiency and low parathyroid hormone levels on long-term hemodialysis: a case report

Introduction Currently, there are no reports of diaphyseal femoral fracture equivalent to atypical femoral fractures (AFFs) in patients receiving long-term hemodialysis (HD). Case report A 56-year-old Japanese man receiving long-term HD for 34 years was admitted to our hospital due to a delay in postoperative healing. The patient began maintenance hemodialysis at 22 years of age. The patient then underwent surgical parathyroidectomy (PTX) for secondary hyperparathyroidism at 43 years of age, which resulted in decreased levels of parathyroid hormone (PTH). Thereafter, this patient’s serum 1,25(OH)2 D3 level was very low because active vitamin D3 derivative was not administered. At 54 years of age, a transverse fracture of the femoral shaft equivalent to AFF occurred. Surgery with open reduction and internal fixation using intramedullary nailing was performed; however, the delay of postoperative healing continued for 16 months. A left iliac crest bone biopsy was performed and showed osteoid-like lesion and an increase of woven bone. The patient received active vitamin D3 derivative and recombinant human PTH (1–34) derivative. Twenty-nine months after the first surgery, a reoperation was performed. Simultaneously, a right iliac crest bone biopsy was performed. Bone morphometrical improvement was confirmed. Six months after resurgery, the bone union was achieved. Summary Severe vitamin D3 deficiency and decreased levels of PTH may induce a higher osteoid state and an increase of woven bone, which may then attribute to the development of diaphyseal femoral fracture and impairment of postoperative bone healing. It is hypothesized that treatment with active vitamin D3 and teriparatide acetate may be a therapeutic option via the accelerated formation of lamellar bone for refractory diaphyseal femoral fracture of long-term dialysis.

Veterinary Cuttable Plate in a Plate-Rod Construct for Repair of Diaphyseal Femoral Fractures in the Cat

Objective This study evaluated retrospectively the effectiveness of the veterinary cuttable plate (VCP) in a plate-rod construct, for the treatment of diaphyseal femoral fractures in cats. Materials and Methods A total of 29 cats with diaphyseal femoral fracture underwent stabilization with a VCP-rod construct. Results Fractures were classified as type A (7/29), type B (11/29) and type C (11/29) following the AO classification. Biological osteosynthesis was elected in three type B and 10 type C fractures, and open approach in the other cases. Pin diameter was 2 mm (n = 16) or 2.5 mm (n = 13); this corresponded to a percentage of pin occupation of 39.9 and 53.0% of the intramedullary cavity respectively. The 2.0/2.7-mm VCP and 2-mm screws were used in all cases. The median length of the VCP was 12 holes, and the median number of screws placed in the plate was 6. The median number of cortices engaged per fragment was 6. Ninety-nine percent of the screws were bicortical. Quadriceps contracture was an unacceptable functional outcome in one cat. Follow-up was available in 20 cases. Complete bone healing was assessed in 16/20 cases with a functional outcome considered as full in 17/20, acceptable in 2/20, and unacceptable in 1/20. Telephonic owner outcome assessment was available for five more cats and was considered as full in all cases. Clinical Significance The VCP-rod construct is effective to manage all configurations of diaphyseal femoral fracture in cats. The high amount of screw holes per unit length of a VCP allows bicortical screws placement without interfering with the intramedullary rod.