Background

Distal radial fractures in the elderly population have been traditionally managed by closed techniques, primarily due to their poor bone quality and low functional demands. Since the introduction of the volar locking plate (VLP), which provides a good fixation in osteoporotic bones, there maybe an increased use of open reduction and internal fixation (ORIF) in the elderly population.

Introduction

Anterior Cruciate ligament reconstruction is a common operation in orthopaedics surgery. A common complication of whilst havesting the hamstring tendon is injury to the infra-patellar branch of the saphenous nerve (IPBSN), resulting in altered sensation to the anterior and lateral aspects of the knee and leg.

Introduction

A common complication whilst harvesting the hamstring tendon in ACL reconstruction is injury to the infra-patellar branch of the saphenous nerve (IPBSN), resulting in altered sensation to the anterior and lateral aspects of the knee and leg.

Due to its popularity of intramedullary nails (IMN) high success rate, newer design (titanium) IMN system have been introduced to replace stainless steel system. However the stability provided by the titanium IMN

may not be adequate, there by influencing the union rate.

We aimed to compare the results of both IMN systems via prospective clinical study and biomechanical testing using RSA.

Introduction: Current existing joint designs, principally flexible silastic spacers, satisfy the initial requirements but commonly lack durability. In particular all flexible silastic joints are prone to early breakage due to abrasion against bone and constant loading of the central section of the flexible implants. The aim of our new small joint design is to overcome many of the deficiencies of the flexible silastic designs while maintaining their main advantage of stabilising joint alignment throughout the flexion range.

Aim: To investigate the wear properties of the new small joint design in both static and dynamic applied loads using finite element analysis (FEA).

Materials: The design is essentially a cross between a flexible spacer and a surface replacement, whereby the spanning flexible spacer is located within the long axes of direct load bearing metacarpal and phalangeal ‘housings’. We have investigated a number of parameters, using finite element analysis (FEA), focussing principally upon the load bearing and wear properties of the new design to both static and dynamic applied loads with reference to the test protocol developed by the Durham group.

Results: Detailed FEA of the new joint design has highlighted the extreme potential durability of the housings and the internal flexible spacer. Our results suggest that the wear characteristics of both housings manufactured from PEEK (Polyetheretherketones) may result in the generation of considerably less wear debris compared with conventional alloy/plastic articulations. In addition, polyurethanes would appear to have better load bearing and wear characteristics than existing silastic materials.

Conclusions: Clearly, if our FEA findings were to be reproduced with biomechanical testing, we would be well placed to introduce durable and readily affordable small joint arthroplasties that may well resolve our current difficulties of treating patients with moderate joint disease in addition to being a realistic alternative for patients with advanced destructive small joint arthritis.

Introduction: The current techniques used for locking the distal end of intramedullary nails with cross screws remain a technical operative challenge for many clinicians. The surgeon uses his/her experience and judgement to locate the distal holes in the intramedullary nail, relying heavily on the use of two dimensional intra operative X-ray images (fluoroscopy) to undertake a three dimensional task. As a result, a large number of X-ray images are frequently required, significantly increasing the radiation exposure to both the patient and the operative team. Also there is an overall proportional increase in the operating time.

Aim: We aimed to develop a simple new radiological alignment jig that would allow the accurate placement of distal locking cross screws during intramedullary nailing, with minimal radiation exposure and without having to visualise the distal screw holes.

Materials and method: Laboratory tests were conducted using plastic femora (Sawbones Limited) fixed with intramedullary nails. Tests were performed three times using each of the different femoral intramedullary nails (Russell-Taylor, Smith & Nephew) investigating whether the length or diameter of the nail had any influence upon the accuracy of distal screw insertion. After successfully concluding the laboratory tests, a limited clinical study was conducted using the new alignment jig to insert distal locking screws in patients.

Results: Both the bench tests and limited clinical study were 100% successful and permitted the clinician to identify the distal holes correctly without needing to visualise the distal screw holes radiologically.

Conclusion: Our initial bench tests and clinical study show that the new alignment jig allows simple and accurate insertion of the distal locking screws with minimal radiological guidance. It also has considerable potential to reduce the overall operating time.

Introduction: For years traditional intramedullary nails (IMNs) have been used with great success to treat long bone fractures, however, based upon our clinical observations, we hypothesise that design changes incorporated into newer femoral IMNs reduces fracture stability resulting is a higher incidence of non-union.

AIMS: To biomechanically test the factors that may reduce fracture stability.

Materials and methods: The fracture fixation model consisted of custom made stainless steel IMNs of different wall thicknesses and outer diameters, cylinders manufactured from stainless steel, aluminium or HDPE of differing inner diameters and wall thicknesses, and 5mm rods made from stainless steel or titanium. The dimensions of the cylinders were chosen to resemble those commonly observed in the distal femur. The test nails and cylinders were connected using a single rod. Axial loading was undertaken up to 2KN (constant rate of 0.5KN/sec) and repeated a minimum of three times. The effects of various factors such as IM nail wall thickness and outer diameter, the alloy from which the rods were manufactured, and, the diameter, wall thickness and material properties of the cylinders were studied.

Results: The factors that most affected stability were the diameter, wall thickness and the material properties of the cylinders, with the least stable configuration being a HDPE cylinder with a diameter of 75mm and a wall thickness of 3mm. By reducing the diameter of the cylinder to 50mm combined with increasing the wall thickness to 5mm, stability increased considerably even when HDPE was used. The stability of each fracture fixation system was further reduced by using titanium rods.

Discussion: In clinical practice, new femoral IMNs permit longer cross screws to be inserted in the distal femur where the diameter is greatest and the cortical bone is thinnest. Since cancellous bone offers little resistance, screws effectively span from one cortex to the other gaining limited purchase in the bone. As a result, the newer IMN systems are more likely to displace regardless of the direction and force applied. This effect is exaggerated by using titanium. Overall the combination of screw length, choice of alloy and cortical thickness could easily explain our unsatisfactory clinical observations.