Localisation and William Macewen`s early brain surgery part I: the controversy

Neurosurgery for the removal of brain tumours based on localising signs is usually dated from the 1884 operation by Bennett and Godlee. However, within weeks of that operation claims were made on behalf of William Macewen, the Glasgow surgeon, to have been the real pioneer of such surgery. According to Macewen's protagonists, he had conducted seven similar operations earlier than Bennett and Godlee and, in a notable 1888 address, Macewen described these seven pre-1884 cases and a number of others operated on after 1884. This paper, which is in two parts, contains an evaluation of the claims made for the priority of Macewen's pre-1884 operations. Part I deals mainly with Macewen's work in fields other than brain surgery that are relevant to it and sets out the facts of the controversy. It begins with a brief biography of Macewen, describes his pioneering work in antiseptic and aseptic surgery, his work on osteotomy and bone regeneration, and his use in brain surgery of the knowledge so gained. Part I concludes with an examination of the battle waged in the newspapers between Macewen's and Bennett's and Godlee's supporters, and of previously unpublished correspondence between Macewen himself, David Ferrier and Hughes Bennett. The primary records of the patients on whom Macewen operated, together with other materials relevant to the controversy, are examined in Part II.

Porous titanium with porosity gradients for biomedical applications

Highly porous titanium and titanium alloys with an open cell structure are promising implant materials due to their low elastic modulus, excellent bioactivity, biocompatibility and the ability for bone regeneration. However, the mechanical strength of the porous titanium decreases dramatically with increasing porosity, which is a prerequisite for the ingrowth of new bone tissues and vascularization. In the present study, porous titanium with porosity gradients, i.e. solid core with highly porous outer shell was successfully fabricated using a powder metallurgy approach. Satisfactory mechanical properties derived from the solid core and osseointegration capacity derived from the outer shell can be achieved simultaneously through the design of the porosity gradients of the porous titanium. The outer shell of porous titanium exhibited a porous architecture very close to
that of natural bone, i.e. a porosity of 70% and pore size distribution in the range of 200 - 500 μm. The peak stress and the elastic modulus of the porous titanium with a porosity gradient (an overall porosity 63%) under compression were approximately 152 MPa and 4 GPa, respectively. These
properties are very close to those of natural bone. For comparison, porous titanium with a uniform porosity of 63% was also prepared and haracterised in the present study. The peak stress and the elastic modulus were 109 MPa and 4 GPa, respectively. The topography of the porous titanium
affected the mechanical properties significantly.

Computer aided analysis of dental radiographic images

This paper is a result of a fruitful cooperation between the computer science and the dental diagnosis experiences. The study presents a new approach of applying computer algorithms to radiographic images of dental implantation used for bone regeneration. We focus here only on the contribution of the computer assistance to the clinical research as the periodontal therapy is beyond the scope of this paper. The proposed system is based on a pattern recognition approach, directed to recognize density changes in the intra-bony affected areas of patients. It comprises different modules with new algorithms specially designed to treat the patients’ radiographic images more accurately. The system includes digitizing, detecting the complicated region of interest (ROI), defining reference area to correct any projection discrepancy of the follow up images, and finally to extract the distinguishing features of the ROI as a basis for determining the rate of new bone density accumulation. This study is applied to two typical dental cases for a patient who received two different operations. The results are very encouraging and more accurate than traditional techniques reported before.

Novel metal structures through powder metallurgy for biomedical applications

Biocompatible porous Ti-16Sn-4Nb alloys were synthesised in quest of a novel tissue engineering biomaterial for bone regeneration. The alloys were prepared from elemental powders via mechanical alloying followed by space-holder sintering. The effects of ball milling variables on the characteristics and mechanical properties of bulk and porous Ti-16Sn-4Nb alloy have been investigated.

Mg-Zr-Sr alloys as biodegradable implant materials

Novel Mg–Zr–Sr alloys have recently been developed for use as biodegradable implant materials. The Mg–Zr–Sr alloys were prepared by diluting Mg–Zr and Mg–Sr master alloys with pure Mg. The impact of Zr and Sr on the mechanical and biological properties has been thoroughly examined. The microstructures and mechanical properties of the alloys were characterized using optical microscopy, X-ray diffraction and compressive tests. The corrosion resistance was evaluated by electrochemical analysis and hydrogen evolution measurement. The in vitro biocompatibility was assessed using osteoblast-like SaOS2 cells and MTS and haemolysis tests. In vivo bone formation and biodegradability were studied in a rabbit model. The results indicated that both Zr and Sr are excellent candidates for Mg alloying elements in manufacturing biodegradable Mg alloy implants. Zr addition refined the grain size, improved the ductility, smoothed the grain boundaries and enhanced the corrosion resistance of Mg alloys. Sr addition led to an increase in compressive strength, better in vitro biocompatibility, and significantly higher bone formation in vivo. This study demonstrated that Mg–xZr–ySr alloys with x and y ⩽5 wt.% would make excellent biodegradable implant materials for load-bearing applications.

Mechanical characterisation of advanced biomedical materials

Biocompatible Ti, Nb and Mo alloy was fabricated in search of a novel biomaterial for bone regeneration. A series of Ti-based alloys were prepared from elemental powders via powder metallurgy technique. The effects of ball milling variables and the agglomerated particles on mechanical properties of the bulk and porous structures were investigated.

Surface modification of biocompatible metallic materials for bone tissue engineering

Titanium, zirconium and TiZr binary alloy were fabricated using a powder metallurgical method. Appropriate surface modifying techniques were conducted on the metals to render an ability for apatite formation. Their biocompatibility has also been assessed. These materials showed potential for biomedical applications because of their excellent bioactivity and biocompatibility which may improve bonding of the implants to juxtaposed bone.