In cementless THA the incidence of intraoperative fracture has been reported to be as high 28% [1]. To mitigate these surgical complications, investigators have explored vibro-acoustic techniques for identifying fracture [2–5]. These methods, however, must be simple, efficient, and robust as well as integrate with workflow and sterility. Early work suggests an energy-based method using inexpensive sensors can detect fracture and appears robust to variability in striking conditions [4–5]. The orthopaedic community is also considering powered impaction as another way to minimize the risk of fracture [6– 8], yet the authors are unaware of attempts to provide sensor feedback perhaps due to challenges from the noise and vibrations generated during powered impaction. Therefore, this study tests the hypothesis that vibration frequency analysis from an accelerometer mounted on a powered impactor coupled to a seated femoral broach can be used to distinguish between intact and fractured bone states. Two femoral Sawbones (Sawbones AB Europe, SKU 1121) were prepared using standard surgical technique up to a size 4 broach (Summit, Depuy Synthes). One sawbone remained intact, while a calcar fracture approximately 40mm in length was introduced into the other sawbone. Broaching was performed with a commercially available pneumatic broaching system (Woodpecker) for approximately 4 secs per test (40 impactions/sec) with hand-held support. Tests were repeated 3 times for fractured and intact groups as well as a ‘control’ condition with the broach handle in mid-air (ie not inserted into the sawbone). Two accelerometers (PCB M353B18) positioned on the femoral condyle and the Woodpecker impactor captured vibration data from bone-broach-impactor system (Fig1). Frequency analysis from impaction strikes were postprocessed (Labview). A spectrogram and area under FFT (AUFFT) [4] were analysed for comparisons between fractured and intact bone groups using a nested ANOVA.Introduction
Methods
In Total Hip Arthroplasty (THA), proper bone preparation technique is fundamental to preventing intraoperative fracture. Anecdotally, surgeons suggest they can avoid fracture by listening for changes in the pitch of a mallet strike during broaching. Consequently, it is not surprising that researchers have explored vibroacoustic methods to prevent [1] and identify bone fractures [2, 3]. For instance, a shift in frequency of the acoustic signals during impaction has been correlated with initial stability [4, 5]. In-spite of these research-based successes, we are unaware of an intraoperative application for THA. We submit that idiosyncratic variability during impaction [6] may overwhelm analytical techniques developed in a controlled laboratory environment. The purpose of this test, therefore, was to evaluate the effect of several strike parameters on the vibro-acoustic response during impaction. Specifically, we hypothesized that the A Sawbones femur (SKU1121, Medium) was prepared and broached using standard surgical technique for the Summit hip system (DePuy Synthes) progressing from size 0 to 4. The size 4 broach was firmly seated and impacted ten times (n=10) for each of the prescribed conditions (Table 1) while securely holding the femur by hand. Vibroacoustic data from an accelerometer attached distally on the femur and a directional microphone located within 1 metre (Figure 1) were acquired at a sampling rate of 40kHz and postprocessed using LabView. Spectrograms were generated for qualitative comparisons, while fast fourier transform (FFT) with normalised amplitudes for each strike facilitated quantitative analysis of the area under the FFT curve (AU-FFT). Strike conditions were monitored to ensure the groups were consistent and distinct (Table 1).Introduction
Methods
The benefits of femoral head-neck modularity in hip surgery have been recognized for decades. However, reports of head/neck taper fretting & corrosion has led to research being conducted, yet the clinical effect of these processes remains unclear. Whilst femoral head size, material and the characteristics of the taper have been a focus of research, potential contributing variables such as From May 2013 to October 2014, nineteen surgeons who specialized in hip surgery from a wide demographic (North America, Europe and Asia) participated in a video review on current surgical practice in total hip arthroplasty (THA). The surgeons were unaware of any specific parameter, including taper assembly, which would subsequently be analyzed. Twenty-seven THA surgeries were reviewed against a specific set of questions relating to factors in the modular femoral head-neck assembly process. The focus of the current study was the number of impaction blows to seat the modular femoral head on the implanted stem.Introduction
Methods
Drug therapy forms an integral part of the management
of many orthopaedic conditions. However, many medicines can produce
serious adverse reactions if prescribed inappropriately, either
alone or in combination with other drugs. Often these hazards are
not appreciated. In response to this, the European Union recently
issued legislation regarding safety measures which member states
must adopt to minimise the risk of errors of medication. In March 2014 the Medicines and Healthcare products Regulatory
Agency and NHS England released a Patient Safety Alert initiative
focussed on errors of medication. There have been similar initiatives
in the United States under the auspices of The National Coordinating
Council for Medication Error and The Joint Commission on the Accreditation
of Healthcare Organizations. These initiatives have highlighted
the importance of informing and educating clinicians. Here, we discuss common drug interactions and contra-indications
in orthopaedic practice. This is germane to safe and effective clinical
care. Cite this article:
Orthopaedic implants are often fixed into place using bone cement. The degradation of the cement mantle has been implicated as playing a major role in the loosening of these implants, and this often necessitates revision surgery. The present work has used the non-destructive acoustic emission (AE) technique to monitor the initiation and evolution of fatigue damage in bone cement constructs. Using this technique, it should be possible to gain an understanding of failure progression in cemented orthopaedic devices. Previous work in this area has focused on AE activity originating from the eventual failure location in order to identify those signatures associated with critical fatigue cracks. This usually involves analysing AE signatures associated with the final stages of failure; however, there have been limited investigations that have looked at the damage that takes up most of the crack propagation life of the sample, (i.e. microcracking formation and development), that occurs away from the failure site, but could still play a role in final failure. In this study, dog-bone-shaped specimens of bone cement were subjected to uniaxial tensile fatigue loading, with damage monitored along the length of specimens using AE. Where specimens exhibited AE activity at locations away from the fracture site, they were sectioned and subjected to synchrotron tomography, which enabled high resolution images of these regions to be obtained. Microcracks of the order of 20 microns were observed in areas where AE had identified early, non-critical damage; in contrast, no microcracking was observed in areas that either remained unloaded or exhibited no AE. To further corroborate these observations, and characterise the damage mechanisms involved, scanning electron microscopy (SEM) was applied to the sectioned samples. In those locations where significant yet non-critical AE occurred, there was evidence of crack-bridging, suggesting that crack closure mechanisms may have slowed down or even arrested crack propagation within the bone cement. These findings further validate the use of AE as a passive non-destructive method for the identification and understanding of damage evolution in cemented orthopaedic devices.
Five specimens were implanted for each group 1) with pedicle screw (into L3 and L5) and tested with/without Synex (expandable) cage anteriorly, 2) implanted with a Synex cage and Double screw+rod Ventrofix system, 3) Synex cage and Double screw+ Single rod Ventrofix construct and 4) Synex cage and Single screw+ Single rod Ventrofix system.
The double screw/ single rod system is less effective than the Ventrofix System but is comparable to the pedicle screw construct. The single screw/ single rod construct leads to unacceptable movement about the axis of the inferior screw particularly in extension with a ROM much greater than the intact spine (p<
0.001)
