Implant Materials for Anterior Column Reconstruction of Cervical Spine Tumor

The spine is the most common site of bone metastases. Many cancer patients will ultimately develop spinal metastatic disease with symptomatic epidural spinal cord compression. At present, the main treatment for cervical spine tumors is surgical resection combined with postoperative radiotherapy. Implant materials for cervical spine anterior column reconstruction need to meet amounts of different properties, such as biocompatibility, bioactivity and the ability to maintain long-term mechanical strength. The selection of different materials determines the surgical efficacy and prognosis of patients to a certain extent. This article provides an overview of a variety of implant materials used for anterior column reconstruction after cervical spine tumor resection, introduces and analyzes their properties, advantages, disadvantages, derivatives, and applications in clinical practice, and looks forward to the future development of implant materials.

Combination of an allogenic and a xenogenic bone substitute material with injectable platelet-rich fibrin - A comparative in vitro study

The aim of the in vitro study was a comparison of an allogenic (ABSM) and a xenogenic bone substitute material (XBSM) with and without injectable platelet-rich fibrin (ABSM-i-PRF & XBSM-i-PRF) on cell characteristics of human osteoblasts (HOB). Here, ABSM and XBSM (+ i-PRF = test; - i-PRF = control) were incubated with HOB for 3, 7 and 10 days. HOB viability, migration, proliferation and differentiation (RT-PCR on alkaline phosphatase (AP), bone morphogenetic protein 2 (BMP-2) and osteonectin (OCN)) were measured and compared between groups. At day 3, an increased viability, migration and proliferation was seen for ABSM-i-PRF. For viability and proliferation (days 7 and 10) and for migration (day 10), ABSM-i-PRF/XBSM-i-PRF showed higher values compared to ABSM/XBSM with maximum values for ABSM-i-PRF and minimum values for XBSM. At days 3 and 7, the highest expression of AP was detected in ABSM-i-PRF/XBSM-i-PRF when compared to ABSM/XBSM, whereas at day 10, AP expression levels were elevated in ABSM-i-PRF/ABSM. The highest BMP-2 expression was seen in ABSM-i-PRF whereas OCN expression showed higher levels in ABSM-i-PRF/XBSM-i-PRF at days 3 and 7 with lowest expression for ABSM. Later on, elevated OC levels were detected for ABSM-i-PRF only. In conclusion, i-PRF in combination with ABSM enhances HOB activity when compared to XBSM-i-PRF or untreated BSM in vitro. Therefore, addition of i-PRF to ABSM and - to a lower extent - to XBSM may influence osteoblast activity in vivo.

[EFFICACY OF BIOACTIVE GLASS AND ALLOGENIC BONE IN REPAIR OF BONE DEFECT AFTER BENIGN BONE TUMOR CURETTAGE]

OBJECTIVE

To compare the healing process and clinical results of bioactive glass and allogenic bone in the repair of bone defects after benign bone tumor curettage.

METHODS

Between November 2011 and December 2012, 20 patients with benign bone tumor received bioactive glass and allogenic bone for repair of bone defects after benign bone tumor curettage. There were 17 males and 3 females, aged 9-68 years (median, 18.5 years). The mean course of disease was 3.3 months (range, 1-9 months). Pathological examination revealed that there were 7 cases of chondroblastoma, 5 cases of bone cyst, 2 cases of non-ossifying fibroma, 2 cases of enchondroma, 1 case of vascular tumor of bone, 1 case of lipoma of bone, 1 case of osteoid osteoma, and 1 case of chondromyxoid fibroma. The lesion located at the femur in 5 cases, at the tibia in 11 cases, at the humerus in 1 case, at the calcaneus in 2 cases, and at the talus in 1 case. The bioactive glass and allogenic cancellous bone were implanted in the cavity at the same time. The Musculoskeletal Tumor Society (MSTS) function evaluation score was used for evaluation of postoperative limb function. According to the imaging and clinical benefit, the healing processes of two kinds of implants were evaluated. The healing rate and healing time were compared. The distribution of the bioactive glass was divided into two layers: the layer close to host bone and the layer close to allogenic bone. The bone ingrowth time and bone resorption time in different layers were evaluated and compared.

RESULTS

All cases were followed up 12-42 months (mean, 34.5 months). All incisions healed by first intention. There were no complications of wound infection or deep infection, rejection, nonunion of bone, fracture at bone graft site, and collapsing of articular surface. There was no tumor recurrence during follow-up. The mean MSTS functional score was 29.5 (range, 28-30) at last follow-up. Complete healing was observed in 11 cases and healing in 9 cases. The healing rates of two kinds of implants were both 100%. The healing time of bioactive glass and allogenic bone was (4.7±1.3) months and (5.2±1.6) months, respectively, showing no significant difference (t=-1.240, P=0.244). The bone ingrowth time and the bone absorption time were (3.6±0.9) months and (3.7±1.0) months in the layer close to host bone and were (4.2±1.3) months and (4.2±1.3) months in the layer close to allogenic bone, all showing no significant difference (t=1.785, P=0.097; t=1.476, P=0.172).

CONCLUSIONS

For the repair of bone defects after benign bone tumor curettage, bioactive glass can achieve satisfactory healing result and has good safety.

Electron beam effect on biomaterials I: focusing on bone graft materials

BACKGROUND

To develop biocompatible bony regeneration materials, allogenic, xenogenic and synthetic bones have been irradiated by an electron beam to change the basic structures of their inorganic materials. The optimal electron beam energy and individual dose have not been established for maximizing the bony regeneration capacity in electron beam irradiated bone.

RESULTS

Commercial products consisting of four allogenic bones, six xenogenic bones, and six synthetic bones were used in this study. We used 1.0-MeV and 2.0 MeV linear accelerators (power: 100 KW, pressure; 115 kPa, temperature; -30 to 120°C, sensor sensitivity: 0.1-1.2 mV/kPa, generating power sensitivity: 44.75 mV/kPa, supply voltage: 50.25 V), and a microtrone with different individual irradiation doses such as 60 kGy and 120 kGy. Additional in vitro analyses were performed by elementary analysis using field emission scanning electron microscopy (FE-SEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and confocal laser scanning microscopy (CLSM). In vivo clinical, radiographic, and micro-computed tomography (Micro-CT) with bone marrow density (BMD) analysis was performed in 8- and 16-week-old Spraque-Dawley rats with calvarial defect grafts.

CONCLUSIONS

Electron beam irradiation of bony substitutes has four main effects: the cross-linking of biphasic calcium phosphate bony apatite, chain-scissioning, the induction of rheological changes, and microbiological sterilization. These novel results and conclusions are the effects of electron beam irradiation.