The <i>in vivo</i> effect of a porous titanium alloy flange with hydroxyapatite, silver and fibronectin coatings on soft-tissue integration of intraosseous transcutaneous amputation prostheses

AIMS: The Intraosseous Transcutaneous Amputation Prosthesis (ITAP) may improve quality of life for amputees by avoiding soft-tissue complications associated with socket prostheses and by improving sensory feedback and function. It relies on the formation of a seal between the soft tissues and the implant and currently has a flange with drilled holes to promote dermal attachment. Despite this, infection remains a significant risk. This study explored alternative strategies to enhance soft-tissue integration. MATERIALS AND METHODS: The effect of ITAP pins with a fully porous titanium alloy flange with interconnected pores on soft-tissue integration was investigated. The flanges were coated with fibronectin-functionalised hydroxyapatite and silver coatings, which have been shown to have an antibacterial effect, while also promoting viable fibroblast growth in vitro. The ITAP pins were implanted along the length of ovine tibias, and histological assessment was undertaken four weeks post-operatively. RESULTS: The porous titanium alloy flange reduced epithelial downgrowth and increased soft-tissue integration compared with the current drilled flange. The addition of coatings did not enhance these effects. CONCLUSION: These results indicate that a fully porous titanium alloy flange has the potential to increase the soft-tissue seal around ITAP and reduce susceptibility to infection compared with the current design

Determining the porous structure for optimal soft-tissue ingrowth: An in vivo histological study

The success of osseointegrated transcutaneous prostheses depends on a soft-tissue seal forming at the skin-implant interface in order to prevent infection. Current designs include a flange with drilled holes or a subdermal barrier with a porous coating in an attempt to promote soft-tissue attachment. However, the soft-tissue seal is not reliably achieved despite these designs and infection remains a significant problem. This study investigated soft-tissue integration into fully porous titanium alloy structures with interconnected pores. The study aimed to determine the effect of altering pore and strut size combinations on soft-tissue ingrowth into porous titanium alloy structures in vivo. It was hypothesized that implants with a more open porous structure with larger pore sizes would increase soft-tissue ingrowth more than less open porous structures. Porous titanium alloy cylinders were inserted into sheep paparaspinal muscles (n = 6) and left in situ for four weeks. A histological assessment of soft-tissue ingrowth was performed. Percentage soft-tissue pore fill, cell nuclei density and blood vessel density were quantified. The results showed that larger pore sizes were supportive of soft-tissue ingrowth. A structure with a pore size of 700μm and a strut size of 300μm supported revascularisation to the greatest degree. A flange with this structure may be used in future studies of osseointegrated transcutaneous prostheses in order to enhance the soft-tissue seal

Augmenting the osseointegration of endoprostheses using laser-sintered porous collars: an in vivo study

AIMS: Massive endoprostheses rely on extra-cortical bone bridging (ECBB) to enhance fixation. The aim of this study was to investigate the role of selective laser sintered (SLS) porous collars in augmenting the osseointegration of these prostheses. MATERIALS AND METHODS: The two novel designs of porous SLS collars, one with small pores (Ø700 μm, SP) and one with large pores (Ø1500 μm, LP), were compared in an ovine tibial diaphyseal model. Osseointegration of these collars was compared with that of a clinically used solid, grooved design (G). At six months post-operatively, the ovine tibias were retrieved and underwent radiological and histological analysis. RESULTS: Porous collars provided a significantly greater surface (p < 0.001) for the ingrowth of bone than the standard grooved design. Significantly greater extracortical pedicle formation was seen radiologically around the grooved design (length p = 0.002, thickness p < 0.001, surface area p = 0.002) than around the porous collars. However, the ingrowth of bone occurred from the transection site into the porous structure of both types of collar. A fivefold increase in integration was seen with the SP and a threefold increase in the LP design when compared with G (p < 0.001). CONCLUSION: SLS porous collars allow the direct ingrowth of more bone and are better than current designs which rely on surface ongrowth and ECBB. Cite this article: Bone Joint J 2017;99-B:276-82

Stem cell therapy for human cartilage defects: a systematic review.

OBJECTIVES: The use of stem cell therapy for the repair of cartilage defects has shown promising results in in vitro and animal studies. However, only a small number of studies have been performed to evaluate the benefits in human subjects. The aim of this study is to systematically review studies that focus on the clinical application of stem cell therapy to treat cartilage defects in human subjects. DESIGN: A literature search was performed, adhering to the PRISMA guidelines, to review any studies using such techniques in humans. Our initial search retrieved 105 articles listed on MEDLINE, EMBASE, Google Scholar, CINHal and SPortDiscus. From these studies, 11 studies meeting the eligibility criteria were selected and formed the basis of our systematic review. RESULTS: There is limited evidence showing the benefit in humans. The study designs, follow-up methods and criteria reporting and evaluation vary greatly between the studies and are outlined in our systematic review. CONCLUSION: With an increasing body of evidence in non-human and in vitro studies, more human trials are required. More high level studies with extensive and robust validated reporting methods should be conducted to evaluate the true effect of such techniques in human cartilage defect repairs

The variation in hip stability measurements between supine and standing radiographs of dysplastic hips

AIMS: The aims of this study were to compare clinically relevant measurements of hip dysplasia on radiographs taken in the supine and standing position, and to compare Hip2Norm software and Picture Archiving and Communication System (PACS)-derived digital radiological measurements. METHODS: Preoperative supine and standing radiographs of 36 consecutive patients (43 hips) who underwent periacetabular osteotomy surgery were retrospectively analyzed from a single-centre, two-surgeon cohort. Anterior coverage (AC), posterior coverage (PC), lateral centre-edge angle (LCEA), acetabular inclination (AI), sharp angle (SA), pelvic tilt (PT), retroversion index (RI), femoroepiphyseal acetabular roof (FEAR) index, femoroepiphyseal horizontal angle (FEHA), leg length discrepancy (LLD), and pelvic obliquity (PO) were analyzed using both Hip2Norm software and PACS-derived measurements where applicable. RESULTS: Analysis of supine and standing radiographs resulted in significant variation for measurements of PT (p < 0.001) and AC (p = 0.005). The variation in PT correlated with the variation in AC in a limited number of patients (R2 = 0.378; p = 0.012). CONCLUSION: The significant variation in PT and AC between supine and standing radiographs suggests that it may benefit surgeons to have both radiographs when planning surgical correction of hip dysplasia. We also recommend using PACS-derived measurements of AI and SA due to the poor interobserver error on Hip2Norm.Ameya Bhanushali, Mukai Chimutengwende-Gordon, Martin Beck, Stuart Adam Callary, Kerry Costi, Donald W. Howie, Lucian Bogdan Solomo