The Femoral Neck System (FNS) was introduced as an alternative device for the fixation of neck of femur fractures (NOFFs). The purported advantages include superior angular and rotatory stability compared to multiple cancellous screws, via a minimally invasive instrumentation that is simpler than conventional fixed angle devices. There were limited clinical studies regarding the utility of this device. We aimed to study the outcomes of NOFFs fixed with the FNS.

This was a single-institution, retrospective review of all undisplaced elderly (≥60 years old) undisplaced young, and displaced young NOFFs fixed with the FNS. Demographics, surgical parameters, radiographic parameters, and clinical outcomes including complications were reviewed.

Thirty-six subjects with a median age of 75 [44,89] years old, had NOFF fixation using the FNS. Thirty-one (86.1%) had undisplaced fractures. There were 6 (16.7%), 26 (72.2%), and 4 (11.1%) subjects with Pauwels types 1, 2, and 3 respectively. Thirty-two (88.9%) had posterior tilt of <20º. The mean duration of surgery was 71±18 minutes. Excluding 4 patients whom required revision surgery, 2 patients whom demised, and 10 patients whom defaulted reviews, the mean follow-up duration was 55±13 weeks. Four complications were recorded, namely implant cut out at the femoral head at week 8, breaking of the locking screw at the run-off region at week 22, avascular necrosis at week 25, and a refracture following near fall, causing the fracture to fail in varus at week 7 postoperation.

While reasonably fast to instrument, failures still occur and it is likely multifactorial. However, the rate of reoperation is lower than what has been reported for NOFFs fixed with the a fixed-angle device or 3 cancellous screws. In conclusion, the FNS is a reasonably safe instrument to use. Surgeons’ discretion is still needed in patient selection, keeping in mind the need for satisfactory radiological parameters.

We present the first systematic review conducted by the UK Defence Medical Services in conjunction with the Cochrane Collaboration. Irrigation fluids are used to remove contamination during the surgical treatment of traumatic wounds in order to prevent infection. This review aims to determine whether there is evidence that one wound irrigation fluid is superior to another at reducing infection. A pre-published methodology was used and two reviewers independently assessed the search results. The search produced 917 studies, of which three met the inclusion criteria. All were studies in open fractures, incorporating a total of 2,903 patients. Each RCT involved a distinct comparison, precluding meta-analysis: i) sterile saline vs. distilled/boiled water; ii) antibiotic solution vs. soap solution; iii) saline vs. soap solution. The odds ratios of infection following irrigation with various fluids was as follows: i) saline vs. distilled or boiled water 0.25 (95%CI 0.08–0.73); ii) antibiotic solution vs. soap 1.42 (95%CI 0.82–2.46); iii) saline vs. soap solution 1.00 (95%CI 0.80–1.26). These results suggest that neither soap nor antibiotic solution is superior to saline and that saline is inferior to distilled or boiled water.

For the management of displaced patellar fractures, surgical fixation using cannulated screws along with anterior tension band wiring is getting popular. Clinical and biomechanical studies have reported that using cannulated screws and a wire instead of the modified tension band with Kirschner wires improves the stability of fractured patellae. However, the biomechanical effect of screw proximity on the fixed construction remains unclear. The aim of this study was to evaluate the mechanical behaviors of the fractured patella fixed with two cannulated screws and tension band at different depths of the patella using finite element method.

A patella model with simple transverse fracture [AO 34-C1] was developed; the surgical fixation consisted of two 4.0-mm parallel partial-threaded cannulated screws with a figure-of-eight anterior tension band wiring using a 1.25-mm stainless steel cable. Two different locations, including the screws 5-mm and 10-mm away from the leading edge of the patella, were used. A tension force of 850 N was applied on the patellar apexes at two loading angles (45° and 0° [parallel] to the long axis) to simulate different loading conditions while knee ambulation. The proximal side (base) of the patella was fixed, and the inferior articular surface was defined as a compression-only support in ANSYS to simulate the support from distal femur condyles. Compression-only support enables the articular surfaces of the present patella to only bear compression and no tension forces.

Under different loading conditions, the fixed fractured patella yielded higher stability during 0° loading of tension force than during 45° loading. When the screws were parallel placed at the depth of 5 mm away from the patellar surface, the deformation of patellar fragment and maximum gap opening at the fracture site were smaller than those obtained by screws placed at the depth of 10 mm away from the patellar surface. Compared to the superficial screw placement, the deeper placement (10 mm) increased the maximum gap opening at the fracture site by 1.56 times under 45° loading, and 1.58 times under 0° loading. The load on the tension band wire of the 10-mm screw placement was 3.12 times (from 230 to 717 N) higher than that of the 5-mm placement. Under the wire, the contact pressure on the patellar surface was higher with the 10-mm screw placement than the 5-mm screw placement. The peak bone contact pressures with the 10-mm placement were 7.7 times (99.5 to 764 MPa) higher.

This is the first numerical study to examine the biomechanical effects of different screw locations on the fixation of a fractured patella using screws and tension band. Based on a higher stability and lower cable tension obtained by the superficial screws placement, the authors recommended the superficial screw placement (5 mm below the leading edge of the patella) rather than the deep screws while fixing the transverse patellar fracture with cannulated screws and cable.

Joint assessment through manual physical examination is a fundamental skill that must be acquired by orthopaedic surgeons. These joint assessments allow surgeons to identify soft tissue injuries (e.g. ligament tears) which are critical in identifying appropriate treatment options.

The difficulty in communicating the feeling of different joint conditions and the limited opportunities for practice can make these skills challenging to learn, resulting in reduced treatment effectiveness and increased costs. This research seeks to improve the training of joint assessment with the creation of a haptic joint simulator that can train surgeons with increased effectiveness.

A first of its kind haptic simulator is presented, which incorporates: a newly defined kinetic knee simulation, a haptic device for user interaction, and a haptic control algorithm. The knee model has been specifically created for this application and allows six degree-of-freedom manipulation of the tibia while considering the effects of ten knee ligament bundles. The model has been mathematically formulated to allow for the high update rates necessary for smooth and stable haptic simulation.

Two quantitative assessments were made of the model to confirm its clinical validity. The first was against the widely used OpenSim biomechanical simulation software. Simulations of the model's performance for both anterior-posterior draw tests and varus-valgus rotation tests showed less than 0.7%RMSE for force and 5.5%RMSE for moments. Crucially, the proposed model could generate updated forces in less than 1ms, compared to 188ms for OpenSim. The second validation of the model was against a cadaveric knee that was tested using a validated robotic testing platform. This comparison showed that the model could generate similar force- motion pathways to the cadaveric knee after the model's parameters were scaled to match.

Having demonstrated that it is possible to create a computational knee model that has good conformance to gold-standard knee simulations and cadaveric recordings, while updating at less than 1ms, this research has overcome a major hurdle. The next stage of this research will be to incorporate the knee model into a full haptic simulator and perform skill acquisition trials. Given the effectiveness of past haptic training systems in aiding clinical skills acquisition, this research offers a promising way to improve surgeon training, and therefore also patient diagnosis and treatment.

Introduction

Total knee arthroplasty [TKA] is a common procedure to relieve painful disability from advanced knee arthritis. However, related blood loss, ranging from 800 to 1200 ml, increase risk and disruption of recovery in anemic patients following TKA. Various methods for blood conservation had been proposed and examined. In the literature, the intra-articular administration of a solution mixing bupivacaine and epinephrine was commonly used after knee surgeries. Therefore, we conducted a retrospective, case controlled review of our primary TKAs to determine the hemostatic efficacy of this regimen following TKAs.

Cannulated screw is commonly used in the fixation of proximal femoral neck fractures. In the literature, several configurations had been proposed for best mechanical support with clinical experiences or biomechanical tests. Although screws in triangle configuration contribute certain fixation stability, but sometimes the surgeons made their own choices have to conduct another fixation pattern for some factors such as fracture type, economic issues, and so on. Therefore the aim of this study is to analyze the mechanical responses of a fractured femur fixed with screws in different configurations, screw materials and screw diameters with finite element method, trying to find the most stable construct.

A solid femur model was built from the CT images of a standard saw bone. Three fracture types of the femoral neck were created according to Pauwel's classification (30?, 50?, 70?) by CAD software. The models of implanted screws were built according to a commercial cannulated screw (Stryker Osteosynthesis, Schoenkirchen/Kiel, Germany) with diameter 6.5mm and 4.5mm by CAD software, too. Three fixation configurations were analyzed in this study, including triangle with superior single screw with titanium diameter 6.5mm, triangle with inferior single screw with diameter 6.5mm and diamond with four stainless screw diameter 4.5mm (fig.1). Totally there were nine models constructed in this study, and all of them were then imported into ANSYS WORKBENCH v14 (Swanson Analysis, Houston, PA, USA) to mesh and further analysis. 700N vertical downward force was applied on the femur head and the distal end of femur shaft was totally fixed.

The triangle fixation with superior single screw resulted in a best stability, but the fracture fixed with screws in a diamond configuration has least fracture gap. The difference of the maximum displacement of the femur head with Pauwel's classification 70?between triangle fixation with superior single screw and diamond configuration is only 0.03mm (1.72–1.69 mm). In most unstable femoral neck fracture [Pauwel's classification 70], the maximum gap distance is 0.59mm under the diamond configuration, while it is 0.63mm as the fracture fixed with a triangle configuration.

Therefore, this study suggests that four 4.5mm stainless screws in a diamond configuration is an alternative for proximal femur fracture once 6.5mm titanium screws are not available.

1.

Introduction

Metal-on-metal (MOM) hip joints have regained a favor in arthroplasty since they own excellent wear resistance. In this study, wear tests by using a hip joint simulator were conducted with MOM bearings of specified 40 mm femoral heads. The influence of clearance on the wear behavior was investigated. Furthermore, an optimized radial clearance was estimated by lubricant film thickness and contact pressure analysis.