Aims

A pilon fracture is a severe ankle joint injury caused by high-energy trauma, typically affecting men of working age. Although relatively uncommon (5% to 7% of all tibial fractures), this injury causes among the worst functional and health outcomes of any skeletal injury, with a high risk of serious complications and long-term disability, and with devastating consequences on patients’ quality of life and financial prospects. Robust evidence to guide treatment is currently lacking. This study aims to evaluate the clinical and cost-effectiveness of two surgical interventions that are most commonly used to treat pilon fractures.

School of Mechanical Engineering, University of Birmingham, Birmingham, UK

This study investigated the effects on friction of changing the dimensions of a ball-and-socket Total Disc Arthroplasty (TDA).

A generic ball-and-socket model was designed and manufactured based on the dimensions and geometry of a metal-on-metal Maverick (Medtronic, Minneapolis, USA) device. Keeping the radial clearance similar to the Maverick, the ball and socket dimensions varied between 10 to 16 mm and 10.015 to 16.015 mm, respectively, in order to enable the comparison between different dimensions. The implants were made out of Cobalt Chrome Molybdenum alloy, with a surface roughness of 0.05 μm.

A Bose spine simulator (Bose Corporation, ElectroForce Systems Group, Minnesota, USA) was used to apply an axial compressive force to the TDA. Axial rotation of ±2° was then applied at various frequencies and the resulting frictional torque measured. The tests were performed under an axial load of 50, 600 and 1200 N and frequencies of 0.5, 1.0, 1.5 and 2.0 Hz, for four different samples of radii 10, 12, 14 and 16 mm (48 combinations in total).

The results showed variation of frictional torque in different frequencies for all four samples under constant axial load. It was observed that the frictional torque had the lowest value for the implant with ball radius of 16mm. It might be concluded that the implant with larger ball radius may create less friction and hence offer a longer life.

Introduction: This abstract describes the development of an effective procedure for removing as much nucleus as possible from an intervertebral disc with minimal disruption to the annulus. The procedure was developed on cadaveric sheep discs which are well established as a model for human discs in studies of this kind. The purpose of the study was to develop a method for removing the nucleus as part of a laboratory study of nucleus replacement; however, it is also intended to guide the development of procedures for the removal of residual nucleus when indicated in surgical procedures that involve replacing the nucleus with synthetic materials.

Methods: All procedures were performed via a 3 mm trocar. Four procedures were compared: (I) unilateral approach using rongeurs alone, (II) bilateral approach using rongeurs alone, (III) unilateral approach using rongeurs followed by chymopapain and (IV) bilateral approach using rongeurs followed by chymopapain. Chymopapain was administered as a solution (30 units in 0.1 cm³ de-ionised water) to a disc at 37^oC. For each procedure (I–IV) 14 discs were used.

Results: The percentages of nucleus removed were: (I) 34 ± 2%, (II) 41 ± 2%, (III) 52 ± 3% and (IV) 75 ± 8%; ANOVA showed a significant differences between the four sets of results (P < 0.05).

Conclusions: Significantly more nucleus is removed using a bilateral than a unilateral approach; significantly more nucleus is removed if chymopapain is used in addition to rongeurs.

A computer-based image analysis system has been developed as a research tool in total hip replacement. The system has been programmed to take multiple measurements from coronal plane radiographs. Poor quality radiographic images can be enhanced and standardised. The measurements which can be obtained include stem subsidence, cup migration, cup wear, and stem loosening. Reproducibility and accuracy were +/- 0.01 mm and +/- 0.5 mm respectively. The present application is in retrospective research, but prospective monitoring of radiographs is planned.