Clinical trial of a low-cost external fixator for global surgery use.

PURPOSE: A low-cost modular external fixator for the lower limb has been developed for global surgery use. The purpose of this study is to assess outcome measures in the first clinical use of the device. METHODS: A prospective cohort study was conducted with patients recruited in two trauma hospitals. Initial clinical procedure data were collected, and patients were followed up every two weeks until 12 weeks or definitive fixation. Follow-up assessed infection, stability, and radiographic outcomes. In addition, patient-reported outcomes and surgeons' feedback on device usability were collected by questionnaires. RESULTS: The external fixator was used on 17 patients. Ten were mono-lateral, five were joint spanning, and two were delta configuration. One patient had a pin site infection at 12-week follow-up. All were stable when tested mechanically and using radiographic assessment, and 53% were converted to definitive fixation. CONCLUSION: The low-cost external fixator developed is appropriate for use in global surgery trauma centres with good clinical outcomes. PROSPECTIVE TRIAL REGISTRATION NUMBER AND DATE: SLCTR/2021/025 (06 Sep 2021).

Low-cost locally manufacturable unilateral imperial external fixator for low- and middle-income countries.

Treating open fractures in long bones can be challenging and if not performed properly can lead to poor outcomes such as mal/non-union, deformity, and amputation. One of the most common methods of treating these fracture types is temporary external fixation followed by definitive fixation. The shortage of high-quality affordable external fixators is a long-recognised need, particularly in Low- and Middle-Income Countries (LMICs). This research aimed to develop a low-cost device that can be manufactured locally to international standards. This can provide surge capacity for conflict zones or in response to unpredictable incidents and situations. The fixator presented here and developed by us, the Imperial external fixator, was tested on femur and tibia specimens under 100 cycles of 100 N compression-tension and the results were compared with those of the Stryker Hoffmann 3 frame. The Imperial device was stiffer than the Stryker Hoffmann 3 with a lower median interfragmentary motion (of 0.94 vs. 1.48 mm). The low-cost, easy to use, relatively lightweight, and easy to manufacture (since minimum skillset and basic workshop equipment and materials are needed) device can address a critical shortage and need in LMICs particularly in conflict-affected regions with unpredictable demand and supply. The device is currently being piloted in three countries for road traffic accidents, gunshot wounds and other conflict trauma-including blast cohorts.

Preliminary biomechanical cadaver study investigating a new load-sharing knee implant.

PURPOSE: One of the major contributors to the progression of knee osteoarthritis (OA) is the condition of loading in the knee joint. Innovatively designed load-sharing implants may be effective in terms of reducing joint load. The effects of these implants on contact joint mechanics can be evaluated through cadaver experiments. In this work, a case study is carried out with cadaver knee specimens to carry out a preliminary investigation into a novel load-sharing knee implant, in particular to study the surgical procedures required for attachment, and to determine the contact pressures in the joint with and without the implant. METHODS: Contact pressure in the tibiofemoral joint was measured using pressure mapping sensors, with and without the implant, and radiographs were conducted to investigate the influence of the implant on joint space. The implant was designed from a 3D model of the specimen reconstructed by segmenting MR images of the knee, and it was manufactured by CNC machining. RESULTS: It was observed that attachment of the implant does not affect the geometry of the hard/soft tissues. Radiographs showed that the implant led to an increase in the joint space on the medial side. Contact pressure measurements showed that the implant reduced the load on the medial side by approximately 18% under all tested loading conditions. By increasing the load from 800 to 1600 N, the percentage of load reduction in the lateral side was decreased by 8%. After applying 800, 1200, and 1600 N load it was observed that the peak contact pressures were 3.7, 4.6, and 5.5 MPa, respectively. CONCLUSIONS: This new knee implant shows some promise as a treatment for OA, through its creation of a conducive loading environment in the knee joint, without sacrificing or damaging any of the hard or soft tissues. This device could be as effective as, for example, the Atlas® system, but without some complications seen with other devices; this would need to be validated through similar results being observed in an appropriate in vivo study.

The influence of an extra-articular implant on bone remodelling of the knee joint.

Bone remodelling is a crucial feature of maintaining healthy bones. The loading conditions on the bones are one of the key aspects which affect the bone remodelling cycle. Many implants, such as hip and knee implants, affect the natural loading conditions and hence influence bone remodelling. Theoretical and numerical methods, such as adaptive bone remodelling, can be used to investigate how an implant affects bone mineral density (BMD). This research aimed to study the influence of an extra-articular implant on bone remodelling of the knee joint using adaptive bone remodelling. Initially, a finite element (FE) model of the knee joint was created. A user-defined material subroutine was developed to generate a heterogeneous BMD distribution in the FE model. The heterogeneous density was then assigned to the knee model with the implant in order to investigate how the implant would affect BMD of the knee joint, five years postoperatively. It was observed that in the medial compartments of the femur and tibia, bone mineral density increased by approximately 3.4% and 4.1%, respectively, and the density for the fixation holes of both bones increased by around 2.2%. From these results, it is concluded that implanting of this load-sharing device does not result in significantly adverse BMD changes in the femur and tibia.

Preliminary study on a novel minimally invasive extra-articular implant for unicompartmental knee osteoarthritis.

The purpose of this research was to study the efficacy of a novel implant for osteoarthritic knees. This implant is designed to eliminate excessive loads through the knee and to provide suitable conditions for possible tibiofemoral cartilage repair. The implant was designed for the medial side of the knee joint. Finite Element Analysis (FEA) was performed for an extended knee position of the knee joint. Von Mises stress and contact pressure distributions on the medial and lateral compartments were investigated as well as stress distributions throughout the implant's plates. Comparison of FEA results with and without the implant showed that the maximum von Mises stress and contact pressure experienced by the femoral cartilage were reduced by 40% and 35%, respectively, after introducing the implant. Furthermore, after attaching the implant, the femur was slightly abducted and more stress and pressure were perceived in the lateral compartment compared to the model without implant. The maximum von Mises stress in the implant (96 MPa) was far lower than the yield strength of Ti-6Al-4V (∼900 MPa), the selected material for manufacturing the implant. According to the above points, this initial study shows promise for the new prosthesis.

Data for factor analysis of hydro-geochemical characteristics of groundwater resources in Iranshahr.

Detection of Hydrogeological and Hydro-geochemical changes affecting the quality of aquifer water is very important. The aim of this study was to determine the factor analysis of the hydro-geochemical characteristics of Iranshahr underground water resources during the warm and cool seasons. In this study, 248 samples (two-time repetitions) of ground water resources were provided at first by cluster-random sampling method during 2017 in the villages of Iranshahr city. After transferring the samples to the laboratory, concentrations of 13 important chemical parameters in those samples were determined according to o water and wastewater standard methods. The results of this study indicated that 45.45% and 55.55% of the correlation between parameters has had a significant decrease and increase, respectively with the transition from warm seasons to cold seasons. According to the factor analysis method, three factors of land hydro-geochemical processes, supplying resources by surface water and sewage as well as human activities have been identified as influential on the chemical composition of these resources.The highest growth rate of 0.37 was observed between phosphate and nitrate ions while the lowest trend of - 0.33 was seen between fluoride ion and calcium as well as chloride ions. Also, a significant increase in the correlation between magnesium ion and nitrate ion from warm seasons to cold seasons indicates the high seasonal impact of the relation between these two parameters.