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| Lens™ Technology Set to Revolutionise Medical Device Manufacture |
| Author: Dr Martin Hedges, Neotech Services MTP, Germany |
| Knee Arthrodesis Using Short, Two-Part, Modular Intramedullary Nails |
| Author: Mr Manoj Sood BSc FRCS(Tr & Orth), Clinical Lecturer, Institute of Orthopaedics, Royal National Orthopaedic Hospital |
| Orthopaedic Digital Templating
With traditional x-ray films disappearing and being replaced with digital images, how will orthopaedic surgeons pre-operatively template? |
| Author: Dr Grant Shaw, Orthopaedic Surgeon, Portsmouth Hospitals Trust, UK |
| A Picture Paints a Thousand Words
Digital Imaging in Orthoapedics |
| Authors: Mr Alex Baker B Sc MRCS, Registrar Orthopaedics
Mr Chris Oliver FRCS (Tr & Orth) DM FRCP DMI RCSEd, Consultant Orthopaedic Trauma Surgeon Edinburgh Orthopaedic Trauma Unit, New Royal Informary of Edinburgh, Old Dalkieth Road, Edinburgh EH16 4SU |
| Computer Assisted Orthopaedic Surgery
(CAOS) |
| Authors: Mr Atul Malik, Research Registrar, Middlesex Hospital and Mr. Micheal Pearse Consultant Orthopaedic Surgeon Central Middlesex Hospital |
|
Lens™ Technology
Set to Revolutionise Medical Device Manufacture Author: Dr Martin Hedges, Neotech Services MTP, Germany Abstract A new class of production technologies, known as Additive Manufacturing (AM), are emerging which have the potential to revolutionise medical device design and manufacture. These techniques are driven directly from CAD data and create components without using traditional tooling. One leading technique, Laser Engineered Net Shaping™ (LENS) is already being examined by medical device manufacturers. The process offers many potential benefits for device design and manufacture, including expanding the range of options for design, reducing manufacturing-related limitations and reducing costs. This article will introduce the technology and present applications in the rapid design and manufacture of medical devices.
Introduction
The medical device design process is particularly complicated because it is driven by a range of complex, interrelated factors: regulatory requirements, patient quality-of-life considerations, as well as practical issues such as durability, weight of the device, manufacturing costs and constraints. This often leads to compromises being made in design and development. A commercially emerging AM technology, Laser Engineered Net Shaping (LENS), promises to greatly expand the range of options for medical device design by removing many manufacturing-related limitations and reducing costs:.Originally conceived at the US Sandia National Laboratories and commercialised by Optomec Inc. (www.optomec.com), the LENS process is an additive manufacturing method where material is deposited layer by layer, direct from CAD data, to build a fully 3D part. This is in contrast to traditional methods such as forging or machining which are subtractive, i.e. material is removed from a part to get the final form. By reversing the process and working additively and without tooling, diverse benefits are obtained, especially in the manufacture of highly shaped parts and fine detailed complex geometries such as those found in medical devices.
Although the LENS process is conceptually similar to well known rapid prototyping techniques, it differs in that the parts are fully functional and created from variety of “real” engineering materials, Table 1. The properties obtained by the LENS process in different alloys are comparable(1 & 2) to forged materials, Table 2, and in several cases exceed them. The reason for this is that,
Lens Process Benfits
1. Rapid Design & ManufactureBefore manufacturing begins, LENS can serve as a powerful prototyping tool. Conventional rapid prototyping systems make sample parts out of paper, polymers, ceramics, and porous metals. These prototypes can be used to study product form and fit but, they generally don’t suffice for functional product testing and use. In contrast, LENS produced parts are fully functional. A newly designed implant or device can be produced, finished and shipped within a matter of hours, offering significant time compression benefits. This has obvious application in the production of one off “customised specials” where a patient requires rapid treatment. As a CAD driven AM process, LENS is both “agile” and “elastic” 3: i.e. total flexibility in implementing design changes is offered and the financial risk associated with the development process is reduced. If a design changes, the CAD file is modified and the new part is simply “printed out” without the need for re-tooling. This feature also opens the way for Mass Customisation for implants: tailored geometries are almost as simple and cost effective to build as standard forms. The system also lets designers modify or rework existing prototypes to test design changes, eliminating the need to fabricate an entirely new part when design changes require only minor modifications.
2. Reduced Cost of Device Manufacture
Although it’s already a capable and cost-effective manufacturing tool, LENS will soon benefit from several initiatives aimed at improving the process. Sponsored by both the US National Medical Technology Testbed (NMTB) and the National Institute of Standards and Technology, LENS is being enhanced specifically for the manufacture of medical implants. These ongoing projects will explore ways to lower the costs of the process, boost the speed and flexibility of LENS manufacturing, improve implant designs and properties. Not only is the production of medical implants potentially more cost effective with LENS, improved design and quality will also contribute large cost savings. Studies in the USA have shown that the LENS process could save the healthcare industry up to $2 billion a year by reducing the number of revision surgeries required to deal with failed implants. Thus, LENS will be increasingly used to create revolutionary designs of novel shape, structure, and material composition, empowering engineers to design better medical devices with improved performance and longer life.
4. Superior Materials Properties.
5. Improved Design Flexibility. Figure 5 shows photographs of demonstration parts with internal structure fabricated as part of a feasibility study using the LENS process. The aim is to exhibit this capability which can be used to make stronger, stiffer, more flexible or lighter parts with novel features.
6. Functional Gradient Materials and Coatings. It should be noted that the bond between materials in a FGM are “metallurgical” in nature: i.e. extremely strong and far higher than those obtained with thermal spraying. As the system operates under an inert argon atmosphere, LENS coat ings are much cleaner than thermal spray coatings. Studies with a leading implant manufacturer have shown that LENS™ can successfully apply biocompatible wear-resistant coatings to Titanium prosthetic devices, significantly reducing wear and improving implant life. The current state of the LENS™ technology allows for binary transitions between alloys; however, ongoing efforts are focused on developing a fully integrated multiple-material capability that allows graded material structures to be created directly from CAD information.
7. Active Implants.
Additional applications for M3D technology in medical design include BioMEMS, BioSensors (to monitor device performance), High Density Interconnects, Packaging and Assembly, Fuel Cells and MicroBatteries, and a variety of other bio-compatible Medical Devices.
Summary
A new class of production techniques, known collectively as Additive Manufacturing, has the potential to revolutionise medical device design and manufacture. Laser Engineered Net Shaping™ (LENS) is one of the leading AM techniques for economically and rapidly fabricating, enhancing and repairing metal components directly from CAD data in a wide range of performance materials. The technique is being applied to provide solutions in a number of performance critical markets including medical device manufacture.
The unique design and performance benefits obtained with LENS in combination with increasing cost competitiveness will allow widespread application in medical device manufacture. Several of the worlds leading medical device OEMs are conducting extensive studies on the application of this technique to benefit patient care and reduce cost. Several examples of LENS manufactured implants produced for medical device companies are currently undergoing extensive testing with the first live implants are expected to be used in early 2004.
References
Knee Arthrodesis Using Short, Two-Part, Modular Intramedullary Nails
Knee arthrodesis is an infrequently performed procedure in the UK but remains a useful salvage procedure in failed knee arthroplasty. Such cases are usually multiply operated failed revision knee arthroplasties with or without associated sepsis, extensor mechanism deficiency or ligament disruption. Other indications for knee arthrodesis include neuropathic arthropathy, paralytic conditions with knee instability, intractable knee pain and malignant and aggressive benign lesions around the knee.Author: Mr Manoj Sood BSc FRCS(Tr & Orth), Clinical Lecturer, Institute of Orthopaedics, Royal National Orthopaedic Hospital
Techniques of Arthrodesis
Broadly speaking, knee arthrodesis can be achieved in three ways, external fixation (including Illizarov techniques), plating and intramedullary nailing. Each technique has its own particular advantages and disadvantages. External fixation relies on the patient being compliant enough both to tolerate the frame for a number of months and, to attend regular outpatient appointments. The issue of pin site and pin tract infection also arises and can necessitate early frame removal and placement into a cast. External fixation does, however, have the advantage that no metalwork is left in situ and it allows some adjustment of position of the arthrodesis, if this proves necessary. Plate arthrodesis provides rigid fixation but, involves considerable soft tissue dissection, which can have significant implications for soft tissue and bone healing. It can also be difficult, in some cases, for the soft tissue envelope to accommodate the two bulky plates that are usually required to achieve sound fixation. A period of restricted weight-bearing is also required and there is a risk of fracture of the femoral and tibial shafts at the stress-riser distal to the plates. Intramedullary nailing allows immediate weight-bearing without the associated problems of an external frame or bulky metalwork. Use of a long antegrade nail is, however, technically demanding and does not always allow arthrodesis in an optimal position. It also involves violating the proximal femur and is not possible in the presence of an ipsilateral femoral prosthesis or when significant deformity of the femur or tibia exists. Short modular two-part nails for arthrodesis address these problems and a number of devices are now available.
Short Modular Two-Part Nails
These nails consist of separate femoral and tibial components that are inserted separately and then bolted together to form a solid nail. Insertion of these nails is relatively straightforward when compared to long intramedullary nails but, it is important that the knee is able to flex to about 900. Three nails are available in the UK at present; the Mayday arthrodesis nail (Orthodynamics), with which the author has the most experience, the Endo-model knee fusion nail (Waldemar Link, distributed in the UK by Splint PLC) and the Neff femorotibial nail (Zimmer). The Mayday (Figure 1) and Neff (Figure 2) nails are uncemented nails whereas the Endo-model nail is available in both uncemented and cemented versions (Figure 3). The femoral and tibial components of the Mayday nail and of the uncemented version of the Endo-model nail are custom made for each individual case. The components of the cemented version of Endo-model nail are available in various diameters and lengths. The components of the Neff nail are available in various diameters but, are of standard length and are designed to be shortened to the desired length intraoperatively. All uncemented nails are designed to achieve a press-fit in the femur and tibia but, interlocking of the components to give additional rotatory stability is possible only with the Mayday nail. All nails have the advantage that they can be inserted through the existing anterior knee incision in the case of failed knee arthroplasties. Unlike long intramedullary nails, the shorter nails minimise the theoretical risk of spreading infection along the shafts of the long bones. A potential disadvantage of these nails, however, is that their removal, if required, would necessitate an anterior cortical window to be made in the distal femur and proximal tibia.
Infected cases can be arthrodesed as a single stage or as a two-stage procedure, with the first stage consisting of explantation of the knee arthroplasty prosthesis, debridement and insertion of an antibiotic impregnated cement spacer. Using a one-stage strategy, the chances of successful arthrodesis without recurrence of infection are increased if the organism is gram positive and if no pus is present. Otherwise, a two-stage strategy may be best.
The Mayday Arthrodesis Nail
The Mayday nail was developed by Orthodynamics in collaboration with Mr John Miller FRCS of the Mayday Hospital, Croydon, originally to treat a specific patient who required a knee arthrodesis in the presence of an ipsilateral total hip arthroplasty. The original device was straight but, further development led to the incorporation of 5° of valgus and 12° of flexion into the device to optimise the position of arthrodesis. The tibial component is routinely interlocked and the addition of anti-torsional flutes to the femoral component allowed its placement without interlocking screws and thus the potential for compression and bone apposition of the arthrodesis on weight bearing. Custom design and manufacture means that the device is optimised for each individual patient and the inventory required for the procedure is minimised. Where necessary, the device can also be made available with a hydroxyapatite coating.
Anteroposterior and lateral radiographs of the femur and tibia with appropriate scaled markers are required to custom design the Mayday nail. Once the operating surgeon has approved the design, the nail is manufactured. This process takes approximately 4 weeks and the components are supplied sterile with a reaming diagram and templates. The technique of insertion of the Mayday nail will now be briefly described. It is inserted through a single anterior knee incision. If the knee does not flex to approximately 900, appropriate capsular releases are performed. The femur and tibia are marked so that correct rotatory alignment can be reproduced with the device in place. The distal femur and proximal tibial surfaces are resected using standard arthroplasty jigs to achieve flat opposing bone surfaces. A zero degree tibial resection and a 50 femoral resection are performed. The femur and tibia are prepared to accept the components using osteotomes, to prepare the bone for the box sections of the components, and reamers, for the shafts of the components (Figure 4). A small window is created in the anterior tibia to allow access to the engagement screw that secures the device when the components are locked together (Figure 5). Typically, only the tibial component is interlocked using the jig provided (Figure 6) to allow some compression to occur on weight bearing as the femoral component subsides a little. The components are impacted into place using appropriate introducers (Figure 7). To avoid resection of too much bone from the tibia and femur, it is often useful to insert the components before any resection and then to determine the degree of resection necessary. Resection can then be performed freehand using the components as guides. Often when arthrodesing a failed knee arthroplasty, very little resection is necessary as compression on weight bearing produces excellent bone apposition. The two components are then reduced and once reduced, secured with the supplied anteroposterior locking bolt (Figure 8).
Post-operatively (Figure 9) the patient is allowed to mobilise full weight bearing as comfort permits. As a precaution, excessive rotatory forces are discouraged as the femoral component is not interlocked, although rotation of the femoral component does not seem to be a problem due to the box-shaped distal end of the femoral component and the derotation flutes. A number of reports exist about the outcome of the use of the Mayday nail. In one report1, the device was used in nine patients; 5 cases of failed infected arthroplasty and 1 each of failed previous arthrodesis, Charcot instability, intractable anterior knee pain and trauma. Solid arthrodesis without the need for further procedures was achieved in all cases at a mean of 10.1 months. No complications occurred. In another report2, the nail was used in 9 patients in all of whom the indication was infected failed revision total knee arthroplasty in multiple operated knees. Three patients had significant soft tissue problems and one had already had a musculocutaneous flap because of wound dehiscence after a previous revision arthroplasty procedure. An early amputation was required because of wound dehiscence and persisting infection in one of these patients but, arthrodesis was obtained in 7 of the other 8 patients at a mean of 5.6 months after the procedure without the requirement for any further procedures. One patient had a persistent discharging sinus and radiographs did not show bony trabeculae crossing the fusion site. Periprosthetic cracks occurred in two patients in this series, but these united uneventfully and both the patients went on to have successful arthrodeses. Thus, the device appears to give encouraging results even with end stage, infected cases arthrodesed as a single stage.
Endo-Model Knee Fusion Nail
This device was developed at the Endo-Klinik and is unique in being available in both cemented and uncemented versions. The cemented version of this device may be useful in infected cases where the sensitivities of the infecting organisms are known since appropriate antibiotics can then be incorporated into the cement to help improve the chances of eradication of infection. The cemented nail was reported to have been successful in achieving arthrodesis in two cases of infected revision total arthroplasties by 4 months3.
Neff Femorotibial Nail
This nail, developed in the USA is unique because the lengths of the components are adjusted intraoperatively by the use of metal cutting instruments. A single report on the use of this nail in 21 patients exists4. The group consisted of 13 patients with malignant tumours around the knee, 5 with failed total knee arthroplasties and 3 with locally destructive benign tumours around the knee. Solid arthrodesis was achieved in 19 patients (90%) at a mean of 8.4 months.
Cost
All three devices cost less than £2800. When comparing the cost of these implants with other techniques of arthrodesis it is important to appreciate that the use of such a device is likely to require fewer outpatient attendances and cause fewer significant complications. Casting is unnecessary and a majority of patients should also require no further procedures to achieve arthrodesis.
Conclusion
The revision burden is likely to increase as more total knee arthroplasties are performed. Infection remains an unsolved problem and salvage procedures for infected multiply operated revision knee arthroplasties will be required. Arthrodesis is one such salvage procedure, and short modular two-part nails offer a number of advantages in achieving this end.
References
Orthopaedic Digital Templating
Hospitals throughout the world are rapidly replacing traditional x-ray films with digital images. This allows faster and more flexible access to images for clinicians and their patients. The computer systems that manage digital images are generically called Picture Archive Communication Systems (PACS).With traditional x-ray films disappearing and being replaced with digital images, how will orthopaedic surgeons pre-operatively template? Author: Dr Grant Shaw, Orthopaedic Surgeon, Portsmouth Hospitals Trust, UK Within 5 years, every major hospital in the UK is likely to be ‘film-less’ and, in the US, it is estimated that 60 percent of hospitals will have adopted digital imaging systems by 2006. Similar changes are in progress throughout the world. The introduction of PACS into orthopaedic departments presents a serious challenge but, also brings the opportunity for significant improvements in patient care. One of the difficult areas is the operating theatre. In the 21st century operating theatre, digital x-rays will be used more like engineering drawings rather than sketch plans for planning orthopaedic operations. This will be achieved by using computer workstations to combine digital x-rays with accurately scaled digital templates of orthopaedic implants.
Templating for Joint Replacement Surgery
Joint replacement surgery accounts for a very large proportion of routine orthopaedic surgery. Plain x-ray images of the joint are of critical importance before, during and after the operation. Over the last few years templating has become more important for planning these operations and is now a mandatory part of the procedure for many joint replacements. The current trend for minimal incision size makes sizing at the table more difficult and places increased reliance on accurate pre-operative planning.
Traditionally, templating has been achieved by using printed acetates of the prosthesis laid over the x-ray film. Once the correct size and position has been established, the acetate is fixed in position with tape and used for visual reference during the operation. This has only ever been used as a rough guide because of variations in magnification of each individual x-ray. Most acetate templates assume a magnification of 115-120% for hips whereas, the actual magnification varies from 110-130%. The exact projection of the bone also distorts the image (i.e. foreshortening of the femoral neck length due to femoral rotation), further reducing the accuracy.
OrthoView Orthopaedic Digital Imaging Solution
OrthoView is an intuitive application which allows templating of digital x-ray images. The software is easy to use and can greatly assist in the planning of hip, knee and shoulder replacements. It has been designed to allow seamless integration with all the major PACS systems, thus providing orthopaedics templating functionality for any existing PACS.By using digital images and high quality digital templates, the accuracy of templating can be greatly improved. This is achieved by overcoming the problem of the variable magnification found with plain radiographic images. Provided the digital x-ray was acquired with a suitably positioned marker, the templates can be imported at exactly the correct scale to remove this inaccuracy. Built-in ‘wizards’ guide surgeons through the templating process. Templating using accurately scaled images provides advantages for the prosthesis supplier. If an unusual prosthesis is required, accurate digital templating allows a more reliable prediction of the likely size. This enables the orthopaedic supplier to concentrate on providing the most useful sizes of prosthesis and instrumentation, rather than transporting the entire inventory for a single operation. For remote hospitals or hospitals with a small turnover, this could prove to be a significant benefit. In addition, templates are never lost or damaged and are available at all workstations in clinics, wards, offices and theatres.
OrthoView Digital Templates
Close collaboration with all the major Orthopaedic manufacturers ensures that high quality, verified digital templates are available. If the manufacturer changes a prosthesis the templates are easily updated by OrthoView and made available.
The OrthoView digital templates are far more than electronic acetates. In addition to being accurate electronic outlines, they also relate to the wizards and are arranged in related families of prosthesis so that when the template is moved or altered, the whole family of sizes also respond. This allows quick seamless comparisons of sizes without the need to reposition each size.
OrthoView software is used in three stages:
1. Scaling
3. Templating. Usually only minor adjustment of the template position will be necessary. The intelligent ‘families’ of templates enable quick and easy comparison of different sizes. The template can be selected and positioned without the help of the wizard if preferred. Once the templating is finished, the image can be printed for the patient’s notes. The electronic file can be saved within the PACS archive. The final report produced by OrthoView identifies the prosthesis by manufacturer’s part number and is useful for reordering. The post operative image can be measured using a “box of electronic tools” to measure the position and angle of the inserted prosthesis. These measurements can be exported to standard Microsoft applications for research and audit.
Conclusion
OrthoView is a powerful and flexible solution to templating PACS images for joint replacement surgery. It not only overcomes the problems of having digital images but also improves the accuracy and usefulness of templating. OrthoView helps surgeons to do their job, which, in turn, improves patient care.
A Picture Paints a Thousand Words
Over the last ten years, digital imaging technology has progressed quickly allowing the handling and storage of large amounts of data. Just 5 years ago, a digital camera would have cost the best part of £1000, now a camera of sufficient quality can cost as little as £200-£300. In this review, we are going to discuss some of the issues that are raised by digital imaging in orthopaedics, the choices of equipment, how it all works and, hopefully pass on some ‘handy hints’ for getting the most out of your camera.
There are many uses to which digital imaging can be put, of which the most obvious is taking pre, post and intra-operative photographs. It can also be of great value in facilitating pre-op planning by enabling communication with other surgeons at a distance. Medical education, research, and documenting injuries in the acute setting can all benefit from this technology.Digital Imaging in Orthoapedics Authors: Mr Alex Baker B Sc MRCS, Registrar Orthopaedics
Equipment
Digital camera’s work by using a light proof box and lens similar to regular cameras but at the back of the box, instead of having film they have a charge coupled device (CCD) (Figure 1).
The quality of the image can therefore be affected by many of the same factors as regular photography. Lighting, shaking and lens quality are still very important but, in digital photography there is another factor to consider; the quality of the CCD. This is what is represented by the Megapixel count. A camera with more Megapixels has a greater number of light detectors in the CDD enabling it to record images in more detail. This all has a bearing on our choice of equipment, and of course, cost. The first choice that you are likely to make is which camera to buy. The simple advice is; the best you can afford! The price of digital cameras ranges from £50 to £5000. Some are too coarse and will be unsuitable for the task, others unnecessarily expensive, but many will perform the job well. In making this choice, it is worth considering the quality of the lens and the manufacturer. Just like a regular camera, the lens focuses the image and will influence the quality of final image considerably. Also, zoom on conventional cameras, is controlled by the lens, on digital cameras it can also be controlled by the CCD. This ‘digital zoom’ works in a similar way to getting a photograph enlarged or looking at the picture under a magnifying glass. You get the impression of looking closer but, this is at the expense of quality and detail. We suggest taking the following into consideration when buying a camera:
Handling digital images, their storage, and display are well within the capabilities of most modern computers and, there is therefore, little to choose between them from a photographic point of view. However, many systems are not calibrated properly and it is well worth using a program such as testscreen (www.programming.de/download/testscreens.zip) to ensure your display is working correctly and displaying the image as accurately as possible.
Photographic Skills
It should be remembered that photography is still an art and an experienced photographer will, despite all the advances in technology, achieve better results that the beginner. A professional digital SLR camera in the hands of a beginner will take just as bad a picture as the camera on the back of your mobile phone!Some common situations in which digital imaging is useful include theatre, photographing x-rays, scanning x-rays and slides and photographing patients.
In Theatre
For most of us taking photographs in theatre is not as easy as you might at first expect. For example, the difficult or interesting case where you most want photographs is the one in which you least want to stop in the middle of to enable them to be taken.
Here are some suggestions to help you get better results early on: -
X-rays
When converting x-rays into digital images, it is possible to use standard flatbed scanners as well as cameras. It you are attempting this, it is worth remembering that x-rays are designed to be looked at with a back-light and your scanner is likely to work with the light from the front. This means you need to create the illusion that the scanner is back lit and the easiest way to do that is to put a piece of reflective white card or bright white paper behind the x-ray when its being scanned. In this way, it is possible to create very detailed digital images of x-rays. In fact, it is easy to over do it. The default setting (usually the maximum resolution of the scanner) will often produce an image that will take all night to scan and fill most of your hard drive. Remember to set the resolution of your scanner to something sensible, 300 dpi (dots per inch) is more than sufficient to produce an image capable of being projected as part of a Powerpoint presentation.
An alternative method and probably the easiest way of getting an x-ray onto computer, is to put it up on an x-ray box and photograph it. If you are doing this, metering and greyscale are particularly important. Try and avoid reflections and play with the white balance but, do not adjust the brightness and contrast or use the black and white mode. Use a tripod to hold your camera still and the macro mode. Autofocus works well in this setting as it uses reflected light to judge the focal distance and it is often hard to manually judge focus on x-rays exactly. Spot meter off an area of mid range grey tone, and reduce the exposure compensation 2 stops (-2). For those with professional cameras, a 55mm macro lens with a shutter speed of 0.5/sec and aperture f5.6 works well (Figure 4).
Once the x-ray is on computer, you can adjust its appearance using one of the software packages described below. With x-rays, it is well worth adjusting the picture colour settings to greyscale 256. This way you will have x-rays that appear black and white rather than shades of green or blue. When recording X-rays it is worth remembering that the patient’s details are likely to be at the corner of your image unless you make a point of obscuring them.
Slides To Images
You may well have a collection of slides that you would like to have stored and available on computer and it is possible to do that using a scanner. It is important to get the slides looking their best before you scan them. The computer won’t be able to compensate for a thumbprint or a hair lying across the slide. Dust is a difficult problem with old slide collections and will need to be removed with an airbrush prior to scanning. If you have several thousand slides this can be a long and labour intensive process. The ideal solution is still to use a scanner, but get your registrar to do it for you! Another alternative is to take a photograph of the slides as a projected image. However, the quality of projectors and the projection surface means the eventual image isn’t as good quality.
Storing and Organising Your Images
When deciding how best to store your images, there are a few basic principles to consider. The storage medium should be stable so your image doesn’t degrade. This is not as simple as it seems as all media degrade to some extent over time. It should also be inexpensive and not take up a lot of physical room. The images should be stored in a rational way so that you will be able to access the image at a later date. Unfortunately, unless you have a sensible file naming system, the computer won’t be able to tell you anything about the subject of the image. Storing the images in more than one place and on more than one media is a good principle perhaps having copies of your images on your laptop, desktop and on CD at home. Some companies will enable you to do this ‘off-site’ backup over the Internet but, if you are going to that you need a very fast Internet connection. When creating file names and a directory structure try and choose something that says something about its contents and is sufficiently flexible to enable others to be added or changed at a later date. Some companies will enable you to do this ‘off-site’ backup over the Internet, but if you are going to do that you will need a very fast internet connection. may look unsightly but, will enable a simple windows search to find all the images on a certain date, of a certain operation, audit code, surgeon etc. The website, www.picmeta.com, gives more information and a program to help you do this. When starting out, it is not obvious that this is required but, it soon becomes a big deal when you want to access ‘that picture of the three part proximal humerus we did last year’. Windows sorts its files in an alphanumeric way. It sorts by the first letter then the second then the third etc. For this reason, when using dates put the year first followed by the month and last the day this way Windows will automatically sort them into date order. For the same reason, don’t use 1, 2, 3 etc use 001, 002, 003 otherwise 1 will appear with 10 and 2, 20 etc.
Software
There are many software packages that are available to manipulate your images once you have taken them. Some of the more commonly used ones include Ablaze Image Manager, ThumbsPlus, Cumulus, Epson's File Factor, Piccolo, PhotoWallet, PIE, ACDSee (PC and Mac), PicaView32, Image Fox, Graphic Workshop Professional, Photopage, Photoshop and many more. Most of these packages will allow you to manipulate your image sufficiently, to label it, adjust the brightness, and greyscale.
Email, Printing and Publishing
Different demands are placed on your images depending on the purpose you want to use them for. If you are going to be publishing the image in a journal then ‘big is best’. Most publishers require the images to be of the highest quality and not compressed in any way. On the other hand, if you are going to be e-mailing the pictures then the opposite is true. There are a number of different file types or ways of storing an image, which use different methods of data storage. Some of the more common ones are:
Image Libraries
There are many medical and other images that can be located and downloaded from the Internet. Some of the following web sites may be useful.
Consent and Ethical Issues
The availability of information over the Internet has heightened the public’s awareness of the issues surrounding operative photographs. In most cases, patients are happy to allow photographs to be taken, although frequently they request to see or have copies of the photograph themselves. Care must be taken because for the patient or relatives the images can appear shocking and gruesome. There is also the issue of patient confidentiality and the Data Protection Act. Guidelines have been issued by most of the Royal Colleges and the GMC. Most highlight the following points
The Future of Digital Imaging.
Digital imaging is demonstrating its usefulness in many different ways. Why go and see your local dermatologist when you can consult ‘the best in the world’, over the web, from the comfort of your own home? Via telemedicine, digital imaging is helping experts give advice to doctors and surgeons from distant locations facilitating more advanced, more remote surgery. E-mail based mailing lists with copies of scanned images enable surgeons to get the opinion of literally thousands of others (good or bad)!
This review has covered some of the current issues raised by the use of digital imaging in orthopaedics and included hints on how to avoid some of the initial problems. As computing technology continues to progress, it is likely that more things will be recorded digitally and familiarity with this technology will become increasingly important.
Computer Assisted Orthopaedic Surgery
(CAOS) Authors: Mr Atul Malik, Research Registrar, Middlesex Hospital and Introduction
The use of computer assisted/guided surgery is ideally suited for the sub speciality of orthopaedics. The bone and the periarticular soft tissue are easily evaluated by various radiological tools i.e. x-rays, CT and MRI scans. These images have the potential to permit simulation of surgical procedure before the patient is taken to the operating theatre. Besides, because of the inherent properties of bone, it is possible to apply intra-operative, the pre-operative images, planning information easily. There is also a well-recognised relationship between accuracy and outcome in orthopaedic surgery, i.e. accurate reduction of fracture and placement of implants leads to a better functional result.Thus, in the past few years, there has been a massive upsurge in the use of computers for orthopaedic surgery. The goal being to develop interactive, patient and procedure specific pre-operative planning and post-operative biological response. Develop more precise and less invasive methods of performance of existing procedures and develop new procedures that cannot be performed without the use of computers. So, the advantage that CAOS gives are:
Technical Steps for CAOS
The principle components of a CAOS are:
Current State of CAOS
While computer assisted industrial operations have been available for half a century, use of computers in surgery have existed for just over two decades. This development has been a slow process as safety is the primary concern. There is now an international society of computer assisted surgery, which was formed by the amalgamation of the European and North American fractions in February 2000.One way of categorising the available systems would be according to independence given to the computer.
1. Passive systems. The first two are used pre-operatively and the later two intra-operatively.
2. Semi active systems.
3. Active or surgeon substituting.
What Lies Ahead?
Augmented reality- this is the display technique that combines supplemental information (CT, MRI) with the real world environment. This will provide the surgeon with a direct spatial relationship between the medical image and the patient. The image is overlaid on the patient to appear in the exact orientation and position as the anatomy. This is to say that the surgeon’s eyes would be replaced with X-ray vision.
Future of CAOS
There is little doubt that the development of CAOS has far reaching prospects. It is already well established that CAOS has the potential to provide a very high degree of accuracy and control that is not possible without these systems. These systems give excellent feedback intra-operatively, the ability control errors and unsurpassable documentation.
At some time in the future, hospitals will regard CAOS as a standard item of surgical equipment. The limitation to reaching this date are not electronic, they are intellectual and mechanical, not to mention the attitude of clinician, administrators and patients. Whilst robots/ computers will never replace surgeons, the surgeon will consider it most unusual to attempt an operation without them.
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1. Scaling.
Ideally, any image used for templating should be acquired with a marker to establish scale. For hip replacements, a THR on the contra- lateral side provides the ideal scale assuming the size of the head is known.
The next best system is for a marker of known size to be placed in the plane of the femoral head or mid joint in the case of knees. The worst case is to use the scale on the x-ray plate. The magnification factor then has to be estimated but, even this is an improvement on traditional templating.
2. Planning.
Wizards have been designed to allow quick identification of key bony landmarks such as the femoral head and the femoral medullary canal. OrthoView will then recommend the template most likely to fit and insert it in the correct position.
