We examined stainless-steel, cobalt-chrome, titanium and alumina and zirconia ceramic femoral heads retrieved at revision surgery. All the heads had articulated against ultra-high-molecular-weight-polyethylene (UHMWPE) acetabular cups. We studied the
Loosening is a well-known complication in the fixation of fractures using devices such as locking plates or unilateral fixators. It is believed that high strains in the bone at the bone-screw interface can initiate loosening, which can result in infection, and further loosening. Here, we present a new theory of loosening of implants. The time-dependent response of bone subjected to loads results in interfacial deformations in the bone which accumulate with cyclical loading and thus accentuates loosening. We used an ‘ideal’ bone-screw system, in which the screw is subjected to cyclical lateral loads and trabecular bone is modelled as non-linear viscoelastic and non-linear viscoelastic-viscoplastic material, based on recent experiments, which we conducted.Aims
Methods
Intraoperative 3D navigation (ION) allows high accuracy to be achieved in spinal surgery, but poor workflow has prevented its widespread uptake. The technical demands on ION when used in patients with adolescent idiopathic scoliosis (AIS) are higher than for other more established indications. Lean principles have been applied to industry and to health care with good effects. While ensuring optimal accuracy of instrumentation and safety, the implementation of ION and its associated productivity was evaluated in this study for AIS surgery in order to enhance the workflow of this technique. The aim was to optimize the use of ION by the application of lean principles in AIS surgery. A total of 20 consecutive patients with AIS were treated with ION corrective spinal surgery. Both qualitative and quantitative analysis was performed with real-time modifications. Operating time, scan time, dose length product (measure of CT radiation exposure), use of fluoroscopy, the influence of the reference frame, blood loss, and neuromonitoring were assessed.Aims
Methods
The aim of this study was to develop a psychometrically sound measure of recovery for use in patients who have suffered an open tibial fracture. An initial pool of 109 items was generated from previous qualitative data relating to recovery following an open tibial fracture. These items were field tested in a cohort of patients recovering from an open tibial fracture. They were asked to comment on the content of the items and structure of the scale. Reduction in the number of items led to a refined scale tested in a larger cohort of patients. Principal components analysis permitted further reduction and the development of a definitive scale. Internal consistency, test-retest reliability, and responsiveness were assessed for the retained items.Aims
Methods
Implant-related infection is one of the leading reasons for failure in orthopaedics and trauma, and results in high social and economic costs. Various antibacterial coating technologies have proven to be safe and effective both in preclinical and clinical studies, with post-surgical implant-related infections reduced by 90% in some cases, depending on the type of coating and experimental setup used. Economic assessment may enable the cost-to-benefit profile of any given antibacterial coating to be defined, based on the expected infection rate with and without the coating, the cost of the infection management, and the cost of the coating. After reviewing the latest evidence on the available antibacterial coatings, we quantified the impact caused by delaying their large-scale application. Considering only joint arthroplasties, our calculations indicated that for an antibacterial coating, with a final user’s cost price of €600 and able to reduce post-surgical infection by 80%, each year of delay to its large-scale application would cause an estimated 35 200 new cases of post-surgical infection in Europe, equating to additional hospital costs of approximately €440 million per year. An adequate reimbursement policy for antibacterial coatings may benefit patients, healthcare systems, and related research, as could faster and more affordable regulatory pathways for the technologies still in the pipeline. This could significantly reduce the social and economic burden of implant-related infections in orthopaedics and trauma.
Patients with recurrent anterior dislocation of the shoulder commonly have an anterior osseous defect of the glenoid. Once the defect reaches a critical size, stability may be restored by bone grafting. The critical size of this defect under non-physiological loading conditions has previously been identified as 20% of the length of the glenoid. As the stability of the shoulder is load-dependent, with higher joint forces leading to a loss of stability, the aim of this study was to determine the critical size of an osseous defect that leads to further anterior instability of the shoulder under physiological loading despite a Bankart repair. Two finite element (FE) models were used to determine the risk of dislocation of the shoulder during 30 activities of daily living (ADLs) for the intact glenoid and after creating anterior osseous defects of increasing magnitudes. A Bankart repair was simulated for each size of defect, and the shoulder was tested under loading conditions that replicate Aims
Patients and Methods
This study investigated the biomechanical performance of decellularized porcine superflexor tendon (pSFT) grafts of varying diameters when utilized in conjunction with contemporary ACL graft fixation systems. This aimed to produce a range of ‘off-the-shelf’ products with predictable mechanical performance, depending on the individual requirements of the patient. Decellularized pSFTs were prepared to create double-bundle grafts of 7 mm, 8 mm, and 9 mm diameter. Femoral and tibial fixation systems were simulated utilizing Arthrex suspension devices and interference screws in bovine bone, respectively. Dynamic stiffness and creep were measured, followed by ramp to failure from which linear stiffness and load at failure were measured. The mechanisms of failure were also recorded.Objectives
Methods
Computer-based applications are increasingly being used by orthopaedic surgeons in their clinical practice. With the integration of technology in surgery, augmented reality (AR) may become an important tool for surgeons in the future. By superimposing a digital image on a user’s view of the physical world, this technology shows great promise in orthopaedics. The aim of this review is to investigate the current and potential uses of AR in orthopaedics. A systematic review of the PubMed, MEDLINE, and Embase databases up to January 2019 using the keywords ‘orthopaedic’ OR ‘orthopedic AND augmented reality’ was performed by two independent reviewers.Aims
Materials and Methods
Using a simple classification method, we aimed to estimate the collapse rate due to osteonecrosis of the femoral head (ONFH) in order to develop treatment guidelines for joint-preserving surgeries. We retrospectively analyzed 505 hips from 310 patients (141 men, 169 women; mean age 45.5 years Objectives
Methods
Loss of motion following spine segment fusion results in increased strain in the adjacent motion segments. However, to date, studies on the biomechanics of the cervical spine have not assessed the role of coupled motions in the lumbar spine. Accordingly, we investigated the biomechanics of the cervical spine following cervical fusion and lumbar fusion during simulated whiplash using a whole-human finite element (FE) model to simulate coupled motions of the spine. A previously validated FE model of the human body in the driver-occupant position was used to investigate cervical hyperextension injury. The cervical spine was subjected to simulated whiplash exposure in accordance with Euro NCAP (the European New Car Assessment Programme) testing using the whole human FE model. The coupled motions between the cervical spine and lumbar spine were assessed by evaluating the biomechanical effects of simulated cervical fusion and lumbar fusion.Objectives
Methods
Secondary fracture healing is strongly influenced by the stiffness of the bone-fixator system. Biomechanical tests are extensively used to investigate stiffness and strength of fixation devices. The stiffness values reported in the literature for locked plating, however, vary by three orders of magnitude. The aim of this study was to examine the influence that the method of restraint and load application has on the stiffness produced, the strain distribution within the bone, and the stresses in the implant for locking plate constructs. Synthetic composite bones were used to evaluate experimentally the influence of four different methods of loading and restraining specimens, all used in recent previous studies. Two plate types and three screw arrangements were also evaluated for each loading scenario. Computational models were also developed and validated using the experimental tests.Objectives
Methods
The aim of this study was to estimate the 90-day risk of revision for periprosthetic femoral fracture associated with design features of cementless femoral stems, and to investigate the effect of a collar on this risk using a biomechanical A total of 337 647 primary total hip arthroplasties (THAs) from the United Kingdom National Joint Registry (NJR) were included in a multivariable survival and regression analysis to identify the adjusted hazard of revision for periprosthetic fracture following primary THA using a cementless stem. The effect of a collar in cementless THA on this risk was evaluated in an Aims
Materials and Methods
Patient-specific (PS) implantation surgical technology has been introduced in recent years and a gradual increase in the associated number of surgical cases has been observed. PS technology uses a patient’s own geometry in designing a medical device to provide minimal bone resection with improvement in the prosthetic bone coverage. However, whether PS unicompartmental knee arthroplasty (UKA) provides a better biomechanical effect than standard off-the-shelf prostheses for UKA has not yet been determined, and still remains controversial in both biomechanical and clinical fields. Therefore, the aim of this study was to compare the biomechanical effect between PS and standard off-the-shelf prostheses for UKA. The contact stresses on the polyethylene (PE) insert, articular cartilage and lateral meniscus were evaluated in PS and standard off-the-shelf prostheses for UKA using a validated finite element model. Gait cycle loading was applied to evaluate the biomechanical effect in the PS and standard UKAs.Objectives
Methods
The use of vitamin E-infused highly crosslinked polyethylene (HXLPE) in total knee prostheses is controversial. In this paper we have compared the clinical and radiological results between conventional polyethylene and vitamin E-infused HXLPE inserts in total knee arthroplasty (TKA). The study included 200 knees (175 patients) that underwent TKA using the same total knee prostheses. In all, 100 knees (77 patients) had a vitamin E-infused HXLPE insert (study group) and 100 knees (98 patients) had a conventional polyethylene insert (control group). There were no significant differences in age, sex, diagnosis, preoperative knee range of movement (ROM), and preoperative Knee Society Score (KSS) between the two groups. Clinical and radiological results were evaluated at two years postoperatively.Aims
Patients and Methods
Patellofemoral arthroplasty (PFA) has experienced significant
improvements in implant survivorship with second generation designs.
This has renewed interest in PFA as an alternative to total knee
arthroplasty (TKA) for younger active patients with isolated patellofemoral
osteoarthritis (PF OA). We analysed the cost-effectiveness of PFA We used a Markov transition state model to compare cost-effectiveness
between PFA and TKA. Simulated patients were aged 60 (base case)
and 50 years. Lifetime costs (2015 United States dollars), quality-adjusted
life year (QALY) gains and incremental cost-effectiveness ratio
(ICER) were calculated from a healthcare payer perspective. Annual rates
of revision were derived from the National Joint Registry for England,
Wales, Northern Ireland and the Isle of Man. Deterministic and probabilistic
sensitivity analysis was performed for all parameters against a
$50 000/QALY willingness to pay. Aims
Patients and Methods
This paper describes the methodology, validation and reliability
of a new computer-assisted method which uses models of the patient’s
bones and the components to measure their migration and polyethylene
wear from radiographs after total hip arthroplasty (THA). Models of the patient’s acetabular and femoral component obtained
from the manufacturer and models of the patient’s pelvis and femur
built from a single computed tomography (CT) scan, are used by a
computer program to measure the migration of the components and
the penetration of the femoral head from anteroposterior and lateral radiographs
taken at follow-up visits. The program simulates the radiographic
setup and matches the position and orientation of the models to
outlines of the pelvis, the acetabular and femoral component, and
femur on radiographs. Changes in position and orientation reflect
the migration of the components and the penetration of the femoral
head. Validation was performed using radiographs of phantoms simulating
known migration and penetration, and the clinical feasibility of
measuring migration was assessed in two patients.Aims
Materials and Methods
