ABSTRACT
INTRODUCTION: The knee is the commonest native joint to develop an infection. A two-stage primary knee replacement, with an interim stage of debridement and cement spacer application, modelled after two-stage revision for periprosthetic joint infections (PJI) has been reported for the management of chronic infections. AIMS: To systematically review the literature to find the infection-free survival and outcomes of this operation and explore its indications. METHODS: PRISMA guidelines were followed for this review. A systematic search of 4 online databases was conducted on 9/8/2020. After reviewing 226 abstracts and applying our selection criteria, 10 papers were selected for full-text review, and 9 included in the final synthesis. RESULTS: On pooled analysis, an infection-free survival of 95.6% (CI 94.7-96.4) was found at 2 years in 139 knees, which was unchanged over the remainder of the follow-up (Mean 3.9 years). The complication rate after final implantation was 6% in those that did not develop reinfection. The mean pooled Knee Society Score (KSS) and KSS Function score among 70 patients (4 papers) was 83.4 (80.1-89.0) and 76.8 (71.5-78.0), respectively. The mean range of motion among 82 patients (6 papers) was more than 100°. CONCLUSIONS: Two-stage primary knee replacement is a safe, effective and reliable procedure with good results in the short to medium term. Further studies are required to lay down precise indications and cost-effectiveness of this procedure, in comparison to other strategies for chronic infection. All joint registries should develop methods to identify patients undergoing two-stage procedures, to understand their long-term survival and outcomes.
ABSTRACT
In this study, an advanced ceramic conversion surface engineering technology has been applied for the first time to self-drilling Ti6Al4V external fixation pins to improve their performance in terms of biomechanical, bio-tribological and antibacterial properties. Systematic characterisation of the ceramic conversion treated Ti pins was carried out using Scanning electron microscope, X-ray diffraction, Glow-discharge optical emission spectroscopy, nano- and micro-indentation and scratching; the biomechanical and bio-tribological properties of the surface engineered Ti pins were evaluated by insertion into high density bone simulation material; and the antibacterial behaviour was assessed with Staphylococcus aureus NCTC 6571. The experimental results have demonstrated that the surfaces of Ti6Al4V external fixation pins were successfully converted into a TiO2 rutile layer (~2 µm in thickness) supported by an oxygen hardened case (~15 µm in thickness) with very good bonding due to the in-situ conversion nature. The maximum insertion force and temperature were reduced from 192N and 31.2 °C when using the untreated pins to 182N and 26.1 °C when the ceramic conversion treated pins were tested. This is mainly due to the significantly increased hardness (more than three times) and the effectively enhanced wear resistance of the cutting edge of the self-drilling Ti pins following the ceramic conversion treatment. The antibacterial tests also revealed that there was a significantly reduced number of bacteria isolated from the ceramic conversion treated pins compared to the untreated pins of around 50 % after 20 h incubation, P < 0.01 (0.0024). The results reported are encouraging and could pave the way towards high-performance anti-bacterial titanium external fixation pins with reduced pin-track infection and pin loosing.
