Objectives. The paradoxical migration of the femoral neck element (FNE) superomedially against gravity, with respect to the intramedullary component of the cephalomedullary device, is a poorly understood phenomenon increasingly seen in the management of pertrochanteric hip fractures with the intramedullary nail. The aim of this study was to investigate the role of bidirectional loading on the medial migration phenomenon, based on unique wear patterns seen on scanning electron microscopy of retrieved implants suggestive of FNE toggling. Methods. A total of 18 synthetic femurs (Sawbones, Vashon Island, Washington) with comminuted pertrochanteric fractures were divided into three groups (n = 6 per group). Fracture fixation was performed using the Proximal Femoral Nail Antirotation (PFNA) implant (Synthes, Oberdorf, Switzerland; n = 6). Group 1 was subjected to unidirectional
Objectives. Legg–Calvé–Perthes’ disease (LCP) is an idiopathic osteonecrosis of the femoral head that is most common in children between four and eight years old. The factors that lead to the onset of LCP are still unclear; however, it is believed that interruption of the blood supply to the developing epiphysis is an important factor in the development of the condition. Methods. Finite element analysis modelling of the blood supply to the juvenile epiphysis was investigated to understand under which circumstances the blood vessels supplying the femoral epiphysis could become obstructed. The identification of these conditions is likely to be important in understanding the biomechanics of LCP. Results. The results support the hypothesis that vascular obstruction to the epiphysis may arise when there is delayed ossification and when articular cartilage has reduced stiffness under
Periprosthetic hip fractures (PPFs) after total hip arthroplasty are difficult to treat. Therefore, it is important to identify modifiable risk factors such as stem selection to reduce the occurrence of PPFs. This study aimed to clarify differences in fracture torque, surface strain, and fracture type analysis between three different types of cemented stems. We conducted biomechanical testing of bone analogues using six cemented stems of three different types: collarless polished tapered (CPT) stem, Versys Advocate (Versys) stem, and Charnley-Marcel-Kerboull (CMK) stem. Experienced surgeons implanted each of these types of stems into six bone analogues, and the analogues were compressed and internally rotated until failure. Torque to fracture and fracture type were recorded. We also measured surface strain distribution using triaxial rosettes.Aims
Methods
To evaluate the effect of ultrasound-targeted simvastatin-loaded microbubble destruction (UTMD In vitro, OA chondrocytes were treated with ultrasound (US), US-targeted microbubble destruction (UTMD), simvastatin (SV), and UTMDAims
Methods
Previous studies have evidenced cement-in-cement techniques as reliable in revision arthroplasty. Commonly, the original cement mantle is reshaped, aiding accurate placement of the new stem. Ultrasonic devices selectively remove cement, preserve host bone, and have lower cortical perforation rates than other techniques. As far as the authors are aware, the impact of ultrasonic devices on final cement-in-cement bonds has not been investigated. This study assessed the impact of cement removal using the Orthosonics System for Cemented Arthroplasty Revision (OSCAR; Orthosonics) on final cement-in-cement bonds. A total of 24 specimens were manufactured by pouring cement (Simplex P Bone Cement; Stryker) into stainless steel moulds, with a central rod polished to Stryker Exeter V40 specifications. After cement curing, the rods were removed and eight specimens were allocated to each of three internal surface preparation groups: 1) burr; 2) OSCAR; and 3) no treatment. Internal holes were recemented, and each specimen was cut into 5 mm discs. Shear testing of discs was completed by a technician blinded to the original grouping, recording ultimate shear strengths. Scanning electron microscopy (SEM) was completed, inspecting surfaces of shear-tested specimens.Objectives
Methods
Osteosynthesis of anterior pubic ramus fractures using one large-diameter screw can be challenging in terms of both surgical procedure and fixation stability. Small-fragment screws have the advantage of following the pelvic cortex and being more flexible. The aim of the present study was to biomechanically compare retrograde intramedullary fixation of the superior pubic ramus using either one large- or two small-diameter screws. A total of 12 human cadaveric hemipelvises were analysed in a matched pair study design. Bone mineral density of the specimens was 68 mgHA/cm3 (standard deviation (Objectives
Materials and Methods
Favourable results for collarless polished tapered stems have been reported, and cement creep due to taper slip may be a contributing factor. However, the ideal cement thickness around polished stems remains unknown. We investigated the influence of cement thickness on stem subsidence and cement creep. We cemented six collarless polished tapered (CPT) stems (two stems each of small, medium and large sizes) into composite femurs that had been reamed with a large CPT rasp to achieve various thicknesses of the cement mantle. Two or three tantalum balls were implanted in the proximal cement in each femur. A cyclic loading test was then performed for each stem. The migration of the balls was measured three-dimensionally, using a micro-computed tomography (CT) scanner, before and after loading. A digital displacement gauge was positioned at the stem shoulder, and stem subsidence was measured continuously by the gauge. Final stem subsidence was measured at the balls at the end of each stem.Objectives
Methods
Fractures of the proximal femur are a common clinical problem, and a number of orthopaedic devices are available for the treatment of such fractures. The objective of this study was to assess the rotational stability, a common failure predictor, of three different rotational control design philosophies: a screw, a helical blade and a deployable crucifix. Devices were compared in terms of the mechanical work (W) required to rotate the implant by 6° in a bone substitute material. The substitute material used was Sawbones polyurethane foam of three different densities (0.08 g/cm3, 0.16 g/cm3 and 0.24 g/cm3). Each torsion test comprised a steady ramp of 1°/minute up to an angular displacement of 10°.Objectives
Methods
Studies reporting specifically on squeaking in total hip arthroplasty have focused on cementless, and not on hybrid, fixation. We hypothesised that the cement mantle of the femur might have a damping effect on the sound transmitted through the metal stem. The objective of this study was to test the effect of cement on sound propagation along different stem designs and under different fixation conditions. An Objectives
Methods
The primary purpose of this meta-analysis was to determine whether statin usage could reduce the risk of glucocorticoid-related osteonecrosis in animal models. A systematic literature search up to May 2015 was carried out using the PubMed, Ovid, EBM reviews, ISI Web of Science, EBSCO, CBM, CNKI databases with the term and boolean operators: statins and osteonecrosis in all fields. Risk ratio (RR), as the risk estimate of specific outcome, was calculated along with 95% confidence intervals (CI). The methodological quality of individual studies was assessed using a quantitative tool based on the updated Stroke Therapy Academic Industry Roundtable (STAIR) recommendations.Objectives
Methods
Over recent years hip arthroscopic surgery has
evolved into one of the most rapidly expanding fields in orthopaedic surgery.
Complications are largely transient and incidences between 0.5%
and 6.4% have been reported. However, major complications can and
do occur. This article analyses the reported complications and makes recommendations
based on the literature review and personal experience on how to
minimise them.
The aim of this review is to evaluate the current
available literature evidencing on peri-articular hip endoscopy
(the third compartment). A comprehensive approach has been set on
reports dealing with endoscopic surgery for recalcitrant trochanteric
bursitis, snapping hip (or coxa-saltans; external and internal),
gluteus medius and minimus tears and endoscopy (or arthroscopy)
after total hip arthroplasty. This information can be used to trigger
further research, innovation and education in extra-articular hip
endoscopy.
The accuracy and precision of two new methods of model-based
radiostereometric analysis (RSA) were hypothesised to be superior
to a plain radiograph method in the assessment of polyethylene (PE)
wear. A phantom device was constructed to simulate three-dimensional
(3D) PE wear. Images were obtained consecutively for each simulated
wear position for each modality. Three commercially available packages
were evaluated: model-based RSA using laser-scanned cup models (MB-RSA),
model-based RSA using computer-generated elementary geometrical
shape models (EGS-RSA), and PolyWare. Precision (95% repeatability
limits) and accuracy (Root Mean Square Errors) for two-dimensional
(2D) and 3D wear measurements were assessed.Objectives
Methods
