Multiple studies have established an inverse relationship between ambient theatre temperatures and polymethyl methacrylate (PMMA) cement setting times. It is also known that allowing cement to equilibrate to ambient theatre temperatures restores expected setting characteristics. One overlooked entity is the transport and storage conditions of cement. This is important in tropical regions, where extreme temperature and humidity may cause rapid cement setting times, resulting in potentially significant intra-operative complications.

This study investigated the relationship between extreme transport and storage conditions of Antibiotic Simplex cement (Stryker), and the effect on setting times at Cairns Hospital, Far North Queensland, Australia.

Fifty units of cement were divided evenly into a control arm and four experimental arms. The experimental arms were designed to mimic potential transport and storage conditions. They included seven days of storage in a medication fridge, on the hospital loading dock, in a cane shed, and in a Toyota Landcruiser parked outdoors during January 2022. Humidity and temperature readings were recorded.

The samples in each group were evenly distributed to equilibrate to theatre conditions for 1 hour and 24 hours. Setting time was recorded when a no. 15 scalpel blade was unable to mark the surface.

All three ‘hot’ exposures setting times were significantly faster for both 1 hour (ρ=0.001) and 24 hours (ρ=0.024) equilibration times. The difference in setting times for the ‘cold’ exposure was not significant for either equilibration times (ρ=1).

To our knowledge, this is the first study investigating cement setting times in tropical climates. Further studies are required to address the effect of these conditions on biomechanical strength of PMMA cement. We conclude that extreme heat and humidity during transport and storage have a statistically significant effect on cement setting times.

Introduction

Carriers of Staphylococcus aureus, both methicillin sensitive (MSSA) and methicillin resistant (MRSA), have an increased risk for health-care associated infections. Despite WHO recommendations there is currently no national screening and eradication policy for the detection of MSSA in the UK or USA. This study aimed to evaluate the effectiveness of current standard MRSA eradication therapies in the context of S. aureus decolonisation prior to joint replacement surgery.

Objectives

Nasal carriers of Staphylococcus (S.) aureus (MRSA and MSSA) have an increased risk for healthcare-associated infections. There are currently limited national screening policies for the detection of S. aureus despite the World Health Organization’s recommendations. This study aimed to evaluate the diagnostic performance of molecular and culture techniques in S. aureus screening, determine the cause of any discrepancy between the diagnostic techniques, and model the potential effect of different diagnostic techniques on S. aureus detection in orthopaedic patients.

Nasal carriers of methicillin sensitive Staphylococcus aureus (MSSA) have an increased risk for health-care associated infections. There is currently no national screening policy for the detection of MSSA in the UK. This study aimed to: evaluate the diagnostic performance of molecular and culture techniques in MSSA screening, determine the cause of any discrepancy between the diagnostic techniques, and model the potential effect of different diagnostic techniques on MSSA detection in orthopaedic patients. Paired nasal swabs for PCR assay and culture of S. aureus were collected from a study population of 273 orthopaedic outpatients due to undergo joint replacement surgery.

The prevalence of MSSA nasal colonisation was found to be between 22.4–35.6%. The current standard direct culturing methods for detecting S. aureus significantly underestimated the prevalence (p=0.005), failing to identify its presence in ∼1/3 of patients undergoing joint replacement surgery.

Modelling these results to national surveillance data, it was estimated that 800–1200 MSSA surgical site infections could be prevented annually in the UK by using alternative diagnostic methods to direct culture in pre-operative MSSA screening and eradication programmes.

Summary Statement

Simulated increases in body weight led to increased displacement, von Mises stress, and contact pressure in finite element models of the extended and flexed knee. Contact shifted to locations of typical medial osteoarthritis lesions in the extended knee models.

Background

Osteoarthritis (OA) is a degenerative, chronic disease of the articular cartilage that affects more than 150 million people [1]. In the knee, OA can begin as either isolated medial OA or isolated lateral OA. Previous research [2,3] shows medial OA and lateral OA have characteristic cartilage lesion locations and progression patterns as well as flexion angles associated with lesion development, indicating strong involvement of mechanical factors in disease initiation. Therefore, it is important to investigate these mechanical factors. Previous studies combined data sets (geometry, motion, load) from separate sources. The aim of the current work was to use a consistent multi-modal approach.