The in vivo 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. Cite this article: Bone Joint J 2017;99-B:393-400.

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.

Enhancing the soft tissue seal around intraosseous transcutaneous amputation prostheses using silanized fibronectin titanium alloy.

The success of intraosseous transcutaneous amputation prostheses (ITAP) relies on achieving a tight seal between the soft tissues and the implant in order to avoid infection. Fibronectin (Fn) may be silanized onto titanium alloy (Ti-6Al-4V) in order to promote soft-tissue attachment. The silanization process includes passivation with sulphuric acid, which alters surface characteristics. This study aimed to improve in vitro fibroblast adhesion to silanized fibronectin (SiFn) titanium alloy by omitting the passivation stage. Additionally, the study assessed the effects of SiFn on in vivo dermal attachment, comparing the results with adsorbed Fn, hydroxyapatite (HA), Fn adsorbed onto HA (HAFn) and uncoated controls. Surface topography was assessed using scanning electron microscopy, profilometry and contact angle measurement. Anti-vinculin antibodies were used to immunolocalize fibroblast adhesion sites. A histological assessment of soft-tissue attachment and cell alignment relative to implants in an in vivo ovine model was performed. Passivation resulted in rougher, more hydrophobic, microcracked surfaces and was associated with poorer fibroblast adhesion than unpassivated controls. SiFn and HAFn surfaces resulted in more favourable cell alignment in vivo, implying that dermal attachment was enhanced. These results suggest that SiFn and HAFn surfaces could be useful in optimizing the soft tissue seal around ITAP.

Rupture of the quadriceps tendon: an association with a patellar spur.

We reviewed the records of 107 consecutive patients who had undergone surgery for disruption of the knee extensor mechanism to test whether an association existed between rupture of the quadriceps tendon and the presence of a patellar spur. The available standard pre-operative lateral radiographs were examined to see if a patellar spur was an indicator for rupture of the quadriceps tendon in this group of patients. Of the 107 patients, 12 underwent repair of a ruptured patellar tendon, 59 had an open reduction and internal fixation of a patellar fracture and 36 repair of a ruptured quadriceps tendon. In the 88 available lateral radiographs, patellar spurs were present significantly more commonly (p < 0.0005) in patients operated on for rupture of the quadriceps tendon (79%) than in patients with rupture of the patellar tendon (27%) or fracture of the patella (15%). In patients presenting with failure of the extensor mechanism of the knee in the presence of a patellar spur, rupture of the quadriceps tendon should be considered as a possible diagnosis.