Enriched mesoporous bioactive glass scaffolds as bone substitutes in critical diaphyseal bone defects in rabbits.

In the field of orthopedic surgery, there is an increasing need for the development of bone replacement materials for the treatment of bone defects. One of the main focuses of biomaterials engineering are advanced bioceramics like mesoporous bioactive glasses (MBG´s). The present study compared the new bone formation after 12 weeks of implantation of MBG scaffolds with composition 82,5SiO2-10CaO-5P2O5-x 2.5SrO alone (MBGA), enriched with osteostatin, an osteoinductive peptide, (MBGO) or enriched with bone marrow aspirate (MBGB) in a long bone critical defect in radius bone of adult New Zealand rabbits. New bone formation from the MBG scaffold groups was compared to the gold standard defect filled with iliac crest autograft and to the unfilled defect. Radiographic follow-up was performed at 2, 6, and 12 weeks, and microCT and histologic examination were performed at 12 weeks. X-Ray study showed the highest bone formation scores in the group with the defect filled with autograft, followed by the MBGB group, in addition, the microCT study showed that bone within defect scores (BV/TV) were higher in the MBGO group. This difference could be explained by the higher density of newly formed bone in the osteostatin enriched MBG scaffold group. Therefore, MBG scaffold alone and enriched with osteostatin or bone marrow aspirate increase bone formation compared to defect unfilled, being higher in the osteostatin group. The present results showed the potential to treat critical bone defects by combining MBGs with osteogenic peptides such as osteostatin, with good prospects for translation into clinical practice. STATEMENT OF SIGNIFICANCE: Treatment of bone defects without the capacity for self-repair is a global problem in the field of Orthopedic Surgery, as evidenced by the fact that in the U.S alone it affects approximately 100,000 patients per year. The gold standard of treatment in these cases is the autograft, but its use has limitations both in the amount of graft to be obtained and in the morbidity produced in the donor site. In the field of materials engineering, there is a growing interest in the development of a bone substitute equivalent. Mesoporous bioactive glass (MBG´s) scaffolds with three-dimensional architecture have shown great potential for use as a bone substitutes. The osteostatin-enriched Sr-MBG used in this long bone defect in rabbit radius bone in vivo study showed an increase in bone formation close to autograft, which makes us think that it may be an option to consider as bone substitute.

Osteogenic Potential of a Biomaterial Enriched with Osteostatin and Mesenchymal Stem Cells in Osteoporotic Rabbits.

Mesoporous bioactive glasses (MBGs) of the SiO2-CaO-P2O5 system are biocompatible materials with a quick and effective in vitro and in vivo bioactive response. MBGs can be enhanced by including therapeutically active ions in their composition, by hosting osteogenic molecules within their mesopores, or by decorating their surfaces with mesenchymal stem cells (MSCs). In previous studies, our group showed that MBGs, ZnO-enriched and loaded with the osteogenic peptide osteostatin (OST), and MSCs exhibited osteogenic features under in vitro conditions. The aim of the present study was to evaluate bone repair capability after large bone defect treatment in distal femur osteoporotic rabbits using MBGs (76%SiO2-15%CaO-5%P2O5-4%ZnO (mol-%)) before and after loading with OST and MSCs from a donor rabbit. MSCs presence and/or OST in scaffolds significantly improved bone repair capacity at 6 and 12 weeks, as confirmed by variations observed in trabecular and cortical bone parameters obtained by micro-CT as well as histological analysis results. A greater effect was observed when OST and MSCs were combined. These findings may indicate the great potential for treating critical bone defects by combining MBGs with MSCs and osteogenic peptides such as OST, with good prospects for translation to clinical practice.

In vivo behavior in rabbit radius bone defect of scaffolds based on nanocarbonate hydroxyapatite.

Bone defects treatment may require the use of biomaterials that behave as a support and promote bone regeneration. Limitations associated with the use of autografts and allografts make it necessary to design new synthetic bone substitutes. Some of the most promising biomaterials currently under investigation are based on nanocarbonate hydroxyapatite (nCHA). In this study, we studied the bone-inducing capacity of nCHA-based scaffolds alone (SAG) and enriched with osteostatin (SAGO) or with bone marrow aspirate(SAGB) after implantation for 12 weeks in a 15-mm long critical defect performed in the radius of New Zealand rabbits. Bone formation obtained was compared with a group with the unfilled defect (CE), as control group, and other with the defect filed with iliac crest autograft (GS), as gold standard. X-ray follow-up was performed at 2, 4, 6 and 12 weeks and µCT and histological studies at 12 weeks. The radiological results showed a greater increment in bone formation in the GS group (75%-100%), followed by the SAG and SAGB groups (50%-75%). µCT results showed an increase of bone volume/tissue volume values in GS group followed by SAG and SAGB groups (0.53, 0.40, and 0.31 respectively) compared with CE group (0.26). Histological results showed limited resorption of the nCHA scaffolds and partial osseointegration in the SAG and SAGB groups. However, in the SAGO group, the presence of connective tissue encapsulating the scaffold was detected. In SAG, SAGB, and increase of bone formation were observed compared with CE group, but less than the GS group. Thus, the investigated materials represent a significant advance in the design of synthetic materials for bone grafting, but further studies are needed to bring their in vivo behavior closer to autograft, the gold standard.

Arthroscopic Subtalar Arthrodesis: Does the Type of Fixation Modify Outcomes?

The goal of the present study was to analyze a modified American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale score, time to union, and the incidence of fusion after isolated arthroscopic posterior subtalar arthrodesis using either 1 or 2 screws of different diameters. We reviewed a consecutive series of 65 patients, mean age 50.0 ± 15.6 years, including 38 males (58.5%) and 27 females (41.5%), who had undergone arthrodesis from May 2004 to February 2011. The mean follow-up duration was 57.5 (range 24 to 105) months. The patients were divided into 3 groups according to the fixation method used: group 1 (n = 12; 18.5%) underwent fixation with one 6.5-mm screw; group 2 (n = 40; 61.5%) with one 7.3-mm screw; and group 3 (n = 13; 20%) with two 7.3-mm screws. An overall statistically significant (p <.0001) improvement was seen in the modified AOFAS scale score for all 3 fixation groups; however, the difference was not statistically significant (p = .79) among the fixation groups. Fusion was achieved in 62 patients (95.4%) after a mean of 12.1 (range 9 to 16) weeks. The difference in the time to union was not statistically significant (p = .781) among the fixation groups. Nine patients (13.8%) experienced complications, and nonunion was significantly (p = .005) more prevalent in the single 6.5-mm screw group. In conclusion, all 3 screw configurations led to improved modified AOFAS scale scores, although nonunion was more common among patients fixed with a single 6.5-mm screw.

Subtalar arthroscopic arthrodesis: Technique and outcomes.

PURPOSE: The goal of this study was to describe the surgical technique and our results with arthroscopic posterior subtalar arthrodesis. MATERIAL AND METHODS: Retrospective case series of 65 patients (38 men and 27 women) averaging 50 years of age (range 21-72 years) undergoing posterior arthroscopic subtalar arthrodesis using one or two percutaneous 6.5-7.3mm screws between May 2004 and February 2011, with a mean follow-up of 57.5 months (range 24-105 months). RESULTS: We achieved a 95.4% union rate after an average of 12.1 weeks (range 9 to 16 weeks). 12.3% of patients suffered complications, including superficial infection, nonunion and need for hardware removal. The AOFAS score improved from 51.5 points (19-61 points) preoperatively to 81.9 points (60-94 points) in the postoperative period. CONCLUSIONS: We describe the surgical technique for arthroscopic subtalar arthrodesis, which as proven to be a safe and reliable technique in our experience, with consistent improvements in AOFAS scores.

Results of Arthroscopic Subtalar Arthrodesis for Adult-Acquired Flatfoot Deformity vs Posttraumatic Arthritis.

BACKGROUND: The goal of this study was to compare results with arthroscopic posterior subtalar arthrodesis between patients treated for adult-acquired flatfoot deformity (AAFD) due to posterior tibial tendon dysfunction and patients with posttraumatic subtalar arthritis. METHODS: Retrospective case series of 61 consecutive patients (group 1: posttraumatic arthritis, n = 37; group 2: AAFD, n = 24) averaging 49 years of age (range, 21-72 years) undergoing posterior arthroscopic subtalar arthrodesis via 1 or 2 percutaneous 6.5- to 7.3-mm screws, with a mean follow-up of 57.5 months (range, 24-105 months). Fusion was defined as the appearance of bony trabeculae across the subtalar joint on standard x-rays, along with clinical signs of union. RESULTS: Patients with posttraumatic arthritis (group 1) were more predominantly male and younger than patients treated for AAFD (group 2). Overall, we achieved a 95.1% radiologic union rate after an average of 11.7 weeks. Complications appeared in 14.8% of patients. Union rate and complications did not differ significantly between groups. American Orthopaedic Foot & Ankle Society (AOFAS) scores improved significantly for both patient groups, although patients with AAFD showed significantly larger improvement and higher postoperative AOFAS scores, even after adjusting for age and sex (mean improvement in AOFAS scores: 27.0 ± 9.1 points for the posttraumatic arthritis group vs 34.9 ± 7.4 points for the AAFD group; P < .001). CONCLUSIONS: Arthroscopic subtalar arthrodesis was a safe and reliable technique, with consistent improvement in AOFAS scores throughout different patient subgroups, as well as comparable time to union and complication rates. Improvements were larger for patients treated for AAFD, even after adjusting for age and sex. LEVEL OF EVIDENCE: Level III, retrospective case series.