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Computer-Assisted Orthopaedic Surgery


1. Basics of Computer-Assisted Orthopaedic Surgery (CAOS)

When surgeons started dissection of cadavers in order to broaden their knowledge on the interior of their patients’ bodies, they could better understand and treat pathologies that were invisible from the exterior. More and more complex interventions could be carried out with increasing experience, in particular after the introduction of anesthesia by Horace Wells in 1844.

L.-P. Nolte, F. Langlotz

2. CT-Based Navigation Systems

Medical imaging modalities in diagnostic and clinical use today offer a wide range of possibilities for design and implementation of computer-assisted surgical systems. Among those modalities, computed tomography (CT) scan has a prominent role, since it provides three-dimensional images of relatively high accuracy. It is especially well suited for orthopaedics, since the bone separates from the rest of the tissue by its intensity, which makes the bone segmentation a relatively simple task.

B. Jaramaz, A. M. DiGioia

3. C-Arm-Based Navigation

The common feature of CT- and C-arm-based surgical navigation is the coupling of the medical image and the surgical action: The surgeon sees the instrument displayed as a virtual instrument in the medical image in real time. This is achieved by using surgical instruments equipped with infrared (IR) LEDs (active markers) or with reflecting spheres (passive markers), enabling the instrument to be ≫seen≪ by a camera.

A. Hebecker

4. CT-Free-Based-Navigation Systems

The success of total knee replacement surgery depends on several factors, including proper patient selection, appropriate implant design, correct surgical technique, and effective peri-operative care. The outcome of total knee replacement surgery is particularly sensitive to variations in surgical technique [1, 2, 8, 12, 13, 16–19, 35, 43, 45]. Incorrect positioning or orientation of implants and improper alignment of the limb can lead to accelerated implant wear and loosening and sub-optimal functional performance. A number of studies have suggested that alignment errors of greater than three degrees are associated with more rapid failure and less satisfactory functional results of total knee arthroplasties [2, 3, 8, 9,11,14, 20, 24, 27, 30, 31, 36–38, 44,46].

S. D. Stulberg

5. Bone Morphing: 3D Reconstruction Without Pre- or Intraoperative Imaging - Concept and Applications

Any computer-assisted procedure can be divided in three steps. The first one is called the perception step. During this stage, we have to build a specific model of the patient undergoing surgery. The second is the reasoning step, during which the surgeon plans the procedure based on the model built at the previous stage. Next, there is the action step. This takes place in the operating room, where the surgeon tries to perform, as accurately as possible, the procedure defined at step two. In practice, these steps are not linear, and are often merged into a computer-assisted surgical protocol (CASP) running on the surgetics system.

E. Stindel, J.-L. Briard, S. Lavallée, F. Dubrana, S. Plaweski, P. Merloz, C. Lefèvre, J. Troccaz

Total Hip Arthroplasty


Navigation: Total Hip Arthroplasty

7. Mini-Incision Techniques and Navigation for Total Hip

Before the era of navigation surgery, total hip arthroplasty has evolved to the degree that, we thought, it is one of the most predictable and efficacious procedures that orthopedic surgery has to offer. Clinical experience with computer-assisted hip systems demonstrated in recent years that synergistic combinations of surgeons and computerized machines may produce results that are better than would be possible otherwise.

A. M. DiGioia, A. Y. Plakseychuk, B. Jaramaz

8. Acetabular Cup Navigation with the OrthoPilot System

Optimal positioning of both cup and shaft is essential for both reduction of the risk of dislocation and for the improvement of longevity [1]. During the last five decades significant progress in hip arthroplasty was achieved due to improvement of materials, fixation techniques, reduction of wear and longevity [1,20]. Still it is not always possible to achieve perfect individual cup position. The final result usually depends on experience and subjective intuition of the surgeon. Improper cup positioning may lead to reduced range of motion, impingement [8], increased wear [3,11] and to a higher risk of dislocation. It is reported to occur between 1 and 9% [1, 6]. The ≫safe zone≪ [16], with 45±io° for inclination and 15±10° for anteversion, cannot be reached when using conventional technique even by experienced surgeons in up to 42% [9]. The range varies from 14 to 65° for cup inclination and from 27° of retroversion up to 47° of anteversion [15]. The main cause for these facts is the lack of information about the three-dimensional position of the pelvis due to unknown amounts of lordosis or kyphosis [5]. Assuming a patient’s straight position, the surgeon uses the position of the operating table as his only eye-controlled orientation on which his manual instruments are based on. Even when using fluoroscopy, the angle of lordosis, and therefore inclination and anteversion angles, cannot be defined exactly.

H. Kiefer

9. Acetabular Cup Navigation with theVectorVision System

Despite technical improvements misplacement of implants leading to complications like dislocation or loosening [2, 3] are still observed in total hip arthroplasty (THA). Especially correct anteversion of the cup can prove difficult if the operating table is used as the only reference level regarding pelvic tilt. Computed tomography (CT) allows for three-dimensional reconstruction of individual pelvic and femoral anatomy providing basic information for modern navigation systems. The navigation system VectorVision has been employed in our hospital since the year 2000. Soft- and hardware are currently the phase VectorVision hip 2.0.

W. H. Kluge, J. Babisch, R. A. Venbrocks

10. Computer-Assisted Planning and Navigation of Total Hip Arthroplasty Using the Navitrack and mediCAD System

Evolving orthopaedic diagnostics and surgery requires increasing precision. With the help of modern medical imaging technologies such as CT and MRI allowing for 2D and 3D anatomical reconstructions, accurate anatomical diagnostic and therapy becomes available. CT scan reconstruction of bone morphology is common practice and a useful tool in planning and performing individual prosthetic surgery [1]. 3D imaging provides a number of advantages compared with conventional radiographs including metric accuracy, magnification factors, and bone morphology. Preoperative planning on 3D models is more accurate and gives hints for possible intraoperative problems. These are important factors for computer-assisted surgery (CAS), a technology that has recently been established as a tool for the orthopaedic-surgical therapy [7, 12, 13]. The most important innovations being the development of surgical robots and advanced navigation systems [5,17].

J. Babisch, F. Layher, R. A. Venbrocks

11. Hip Cup Implantation Using the SurgiGATE System

Experiences gained with systems developed for placement of pedicle screws led to the transmission of this new knowledge to the field of hip cup placement. DiGioia et al. [4] presented a system in 1998 which enabled CT-based planning of the position of the hip cup, simulated the range of motion especially with regard to impingement and made it possible to achieve the exact planned position by the means of an intraoperative navigation system[5].

M. Stockheim, J. Krämer

12. Hip Navigation Using the SugiGATE System in Dysplastic and Revision Cases

Opponents to CT-guided navigation of acetabulum components in total hip arthroplasty (THA) argue that this technique is not problem oriented, time consuming with additional radiation, and too inconvenient for practical routine use. Therefore, two- and three-dimensional fluoroscopic systems have been developed as well as on purely kinematics based systems, such as the OrthoPilot (Aesculap, Tuttlingen, Germany).

R. G. Haaker

13. Femoral Stem Navigation with the SurgiGATE System

While robotics in total hip replacement (THR) is applied during the preparation of the femoral cavity, surgical navigation for THR has its roots in the placement of acetabular cups. Based on anatomical bony landmarks, a pelvic coordinate system was defined allowing for precise computer-assisted alignment of the implant. Different approaches have been realized to optimize cup placement. Navigation systems based on preoperative CT scans compete with those using direct digitalization or kinematic analysis for landmark acquisition. Recent developments led to a CT-free navigation system based on registered fluoroscopy and direct landmark digitization. Neither time-consuming preoperative planning nor error-prone intraoperative registration is required with this approach. The existing systems have a patient-specific pelvic reference coordinate system in common, enabling exact realization of the correct anteversion and inclination of the cup independently from the intraoperative position of the patient.

F. Langlotz, A. Marx, M. Kubiak-Langer, G. Zheng, U. Langlotz

14. Minimally Invasive Hip Surgery with Imageless Navigation

The concepts of minimally invasive surgery and computer-assisted surgery have recently come to the forefront of total hip arthroplasty (THA). These techniques have been borrowed from other surgical disciplines and have been introduced to Orthopedics independently. Minimally invasive techniques and surgical navigation have both been used, to some degree, in THA for several years, but only recently have the techniques been merged. With the introduction of specialty instruments and imageless navigation the combined technique has matured to a point were we can demonstrate a measurable early postoperative benefit and hopefully a long term benefit as measured by clinical outcome. Total hip arthroplasty is one of the most successful surgical procedures performed today. The history of THA is littered with attempts to improve outcome that have, with time, shown disappointing results. Few, however, would disagree with the goals of creating less soft tissue damage at the time of the procedure and being able to more accurately and reproducibly position the components; it being understood that long term hip function and implant survivorship are not decreased.

M. Nogler, M. Krismer, F. Rachbauer, J. Sledge

Robotics: Total Hip Arthroplasty

15. Robotic Hip Surgery and Current Development with the ROBODOC system

Why use a robot in joint replacement surgery? The answer is, it allows the surgeon to execute the preoperative plan, and to machine the bone interface to maximize contact.

W. Bargar

16. Robotically Milled Bone Cavities in Comparison with Hand-broaching in Total Hip Replacement

Long-term results and clinical success of a cementless hip stem decisive depend on the primary stability at the time of operation and is the most important factor for osseo-integration (1,6,13,15) Noble et al. (14) have emphasized the difficulties of achieving press-fit and demonstrated the influence of stem design and anatomical variations of the proximal femur. Gaps between implant and bone may particularly occur when contemporary broaching techniques are used which are susceptible to surgical error (18). As a consequence, more sophisticated methods of bone cavity preparation have emerged. Experimental work has led to the development and clinical introduction of robotic systems for orthopaedic surgical application (17).

M. Thomsen

17. An Automically Shaped Prothesis Stem

≫We had these beautiful implants that were made to fit the individual extremely accurately. We had also broaches that were the same sizes as the implant… but then we had to take a 2 1/2 lb mallet and ram it down the bone in order to cut inside of the bone out. The bone sometimes were cracking and the implants were sitting up too high or down too low… We found that other surgeons around the country were having the same problems.≫ - Howard A. Paul ≫.. Luckily robots can do all this betters.≪ - Russel H. Taylor

James B. Stiehl, Werner H. Konermann, Rolf G. Haaker

18. Clinical Experiences with ROBODOC In Total Hip Arthroplasty

The most important precondition for the durability of an implant is its primary stability. The goal of any cement-less THA is osteointegration. This means direct contact between the implant and the bone. Besides implant design, implant surface and materials, the surgical technique is a major factor for long-lasting stability. A conical fixation of femoral implants guarantees a high primary stability in cement-less THA. The way of fixation of the implant in the femoral cavity and the load transfer play a major role in durability of the implant. To gain an optimal fixation of the implant a robot has been used for cement-less THA at BGU Frankfurt since 1994. The 3D preoperative planning data is transferred to the robot that mills out the femoral cavity and guarantees an optimal press-fit of the implant. So far the system has been used on more than 5000 patients. Due to the excellent postoperative results three robots are in daily use at BGU Frankfurt by now.

M. Boerner, U. Wiesel

19. Minimally Invasive Total Hip Replacement — Application of Intraoperative Navigation and Robotics

The classical extensive approach to the hip joint used for total hip alloarthroplasty usually gives the surgeon a good view and orientation. On the other hand, patients prefer minimally invasive operations. This applies also to total hip replacement surgery. The advantages of a minimally invasive surgical technique are accompanied with higher demands to the surgeon because the limited field of view makes spatial orientation difficult. To compensate the surgeon’s limited three-dimensional coordination and to ensure an optimal spatial orientation of the implants, intraoperative navigation and mechatronic instruments like robots are useful

F. Kerschbaumer, S. Kuenzler, J. Wahrburg

20. Cement Removal with the ROBODOC System in Total Hip Arthroplasty Stem – Revision

In the case of aseptic or septic loosening of a cemented femoral component in a total hip arthroplasty (THA), the old stem, including the complete cement has to be removed (5). After removal of the prosthesis, which usually can be performed without any problems, two distinct portions of cement remain in the cavity (Fig. 20–1). In the area of the prosthesis usually a relatively thin layer of cement can be found. Underneath the tip of the prosthesis a solid cement plug remains. The removal of proximal parts of the cement mantle is easy whereas distal mantle parts and the cement plug often constitute more complex problems.

M. Nogler, M. Krismer

21. Advantages of Custom-Made Stems Using Adaptiva Components

The first custom-made stem was implanted by Aldinger in Tuebingen, Germany, in 1987. Based on these experiences the third generation cementless Adaptiva stem design was developed by Prof. Kusswetter in Tuebingen. In con­trary to older round stem designs the new custom-made stem has a square cross-section and three metaphyseal fins and consists of Titanium-Aluminum-Vanadium alloy (TiAl6V). With this fit without fill design high primary and rotational stability is warranted within the femoral shaft. When stems are implanted without cement, a funnel shape stem and a rotationally stable design of the stem are required for optimal results. Both factors lead to a primary stable stem implantation, since loosening of the stem appears to occur within that proximal Gruen zone 1.

G. Gruber

22. Computer- Assisted Designed Hip Arthroplasty

The recent general use of computering technology in the operating room to assist the surgeon during the surgery corresponds to the achievement of a global concept which starts at the time of the stem conception, or at the time of computerized pre-operative planning in case of individual stem solution.

J.-N. Argenson, X. Flecher, J.-M. Aubaniac

23. Navigation and Robotics in Joint and Spine Surgery

James B. Stiehl, Werner H. Konermann, Rolf G. Haaker

6. Basic of Total Hip Replacement Surgery

Total hip replacement has emerged as one of the most successful treatments available in modern medicine, with extraordinary gains in pain relief, quality of life, return to normal function. A large body of knowledge has developed regarding the implants surgical, techniques, the general outcomes. This review will cover recent concepts in the basic approach but will not deal with special conditions or treatment of complications.

B. J. Thomas, J. B. Stiehl

Total Knee Arthroplasty


Navigation: Total Knee Arthroplasty

31. Postoperative Alignment of Conventional and Navigated Total Knee Arthroplasty

Total knee arthroplasty (TKA) requires attention to the entire complex of knee joint mechanics, active muscle forces and passive ligament structures. Prosthetic component design must accommodate the patients knee anatomy, biomechanical stability, function, and mobility. It is uniformly reported in the literature that the longevity of a knee prosthesis is patient specific, but depends upon correct component design and alignment, implant fixation, soft tissue balancing and a physiological lower extremity axis [1,12,15,17,22,24]. One has to appreciate that minimal mal-positioning of intra- or extra-medullary tools may lead to considerable variations of implant positioning. Thus reconstruction of the correct mechanical lower extremity axis as well as soft tissue balancing is vital for good results.

W. H. Konermann, M. A. Saur

32. Computer-Assisted Implantation of Total Knee Endoprosthesis with no Preoperative Imaging: the Kinematic Model

Computer-assisted surgery began at the end of the 1980s with stereotactic neurosurgery [13]. The objectives of this new technique were to increase the precision, reduce the invasiveness and improve the validation of the operation.

D. Saragaglia, F. Picard

33. Computer-Assisted Navigation with the OrthoPilot System Using the Search Evolution TKA Prosthesis

New evolving technology usually lacks sufficient data indicating clear advantages to conventional methods. We, therefore, performed a five-center study in order to demonstrate the consistency and superiority of the OrthoPilot navigation system in TKA.

U. Clemens, W. H. Konermann, S. Kohler, H. Kiefer, J. Y. Jenny, R. K. Miehlke

34. The OrthoPilot Navigation System in Total Knee Arthroplasty: Version 4.0

Following its development period from 1993 to 1997 [12] in joint and spinal surgery, the OrthoPilot system has proved its technical efficiency from 1997 onwards in a cadaver study [9] and in subsequent clinical trials [7]. Moreover, the OrthoPilot navigation system has also shown substantially better results compared with the use of manual instrumentation [2–4,8,11]. It was reported in a multicenter study [1] that a statistically significant improvement in the alignment of the knee prosthesis components in respect of the mechanical leg axis and the femoral and tibial individual axes could be achieved with the OrthoPilot system as opposed to the manual technique. It should be noted here that the ≫learning curve≪ of all the centers taking part was included in the results. The superiority of the navigated implantation technique became particularly obvious when the five set parameters of o° ± 30 for the mechanical axis and 90° ± 2° for the individual axes were observed.

R. K. Miehlke, R. G. Haaker, W. H. Konermann

35. Navigated Implantation of the Columbus Total Knee Arthroplasty with the OrthoPilot System: Version 4.0

We started the OrthoPilot-assisted implantation of the Search Evolution knee endoprosthesis (Aesculap,Tuttlingen, Germany), which was the implant available for use with navigation at the time, in our hospital in June 1999 [1]. Stulberg, Saragaglia and Miehlke have already described the OrthoPilot navigation system in detail in various chapters in this volume, and reported on the good prosthesis alignment they were able to achieve. In our own patients we have compared the radiological results in 110 cases. 55 patients were treated with navigated Search Evolution knee replacements and 55 with conventionally implanted Press Fit Condylar (PFC) knee endoprostheses (DePuy, a Johnson&Johnson Company). It should be borne in mind that the navigated cases constituted our first patient series, and were therefore affected by the learning curve, whereas for conventional implantation of the PFC system we already had years of experience in our hospital to draw on.

F. Lampe, E. Hille

36. CT-Free Navigation Including Soft-Tissue Balancing:LCS-TKA and VectorVision Systems

The specific challenges in total knee replacement surgery are sufficiently well known. In order to obtain excellent long-term results, the following criteria have to be considered: General criteria Selection of the right patientCorrect determination of indications for usePeri-operative managementSpecific criteria Design of the prosthesisSurgical techniques, implantation techniquesReconstruction of the mechanical leg axisReconstruction of the joint lineLigament balancing Mal-alignment of the mechanical leg axes, the prosthesis and the imbalance of the soft tissue, reduce the life span of knee implants [4,7].

W. H. Konermann, S. Kistner

37. Navigation and soft-Tissue Balancing of LCS Total knee Arthroplasty

Of all orthopedic surgical procedures, endoprosthetic total joint replacement today is the most frequent one. While the frequency of total knee replacements in Europe is on a constant rise, in the US total knee replacement has already become more frequent than total hip procedures.

J. M. Strauss, W. Rüther

38. CT-Free Navigation with the LCS Surgetics Station: A New Way of Balancing the Soft Tissues in the TKA Based on Bone Morphing

Total knee arthroplasty (TKA) aims at achieving a painfree, stable, mobile and durable knee. With proper selection and good technique, pain relief should be obtained. Obtaining mobility, with a full range of motion, without instability is rather more challenging. Both mobility and stability are very important for implant longevity.

J. L. Briard, E. Stindel, S. Plaweski, F. Dubrana, P. Merloz, C. Lefevre, J. Troccaz, F. Bertrand, N. Begoc, P. Solodky, M. Breysse

39. The Galileo System for Implantation of Total Knee Arthoplasty

The following factors are essential for the long-term success of knee implants: Correct three-dimensional placement of the implant [1,4,5,8,10,12].Exact ligament balancing to ensure equal-sized, rectangular flexion and extension gaps [7]. The Galileo system is a modern, practical navigation system with an integrated mini-robot. A ligament tension measuring device additionally permits ligament tension to be measured in flexion and then applied to the extension gap using a computer-controlled mini-robot.

P. Ritschl, Jun F. Machacek, R. Fuiko, R. Zettl, B. Kotten

40. Clininical Experiences with the Surgetics System in TKA

Navigation has developed to an inherent part of orthopaedic surgery. Navigation technology seems to void the same fate compared with robotics as demonstrated in numerous successful practical experiences and scientific reports [4,5,7,9]. In addition, navigation does not try to replace surgeons skills, but enhances intraoperative accuracy by delivering geometric data, thus keeping surgical control in the hand of the surgeon. Navigation tools differ considerably from conventional instruments such as capture blades and resection blocks because of its opto- and magnetic-electronics. However, one should keep in mind that classical tool still represent mechanical navigational instruments.

U. Böhling, J. Scholz, R. Nassutt, H. Grundei

41. Navigation in TKA with the Navitrack System

Navigation systems are gaining popularity in total knee arthroplasty (TKA). These systems should improve the exactness of implant positioning [5]. A reduction of aseptic loosening and better functional results are expected [3, 4, 10].

T. Mattes, W. Puhl

42. Clinical Experience with the CT-Based VectorVison System

Since the very beginning of total knee arthroplasty for osteoarthritis and rheumatoid arthritis the number of procedures performed worldwide has continuously increased in the last decades. The component design has changed from hinged to non-constrained implants with the advantage of more preserving bone resections and ligament stability. The femoral component in particular changed from a single radius to more anatomical radii for conforming the femoral shape and appreciation of the patellar groove. Modern TKA kinematics rely on both active and passive soft tissue kinematics and provide increased bone mass for revisions.

M. Wiese, K. Schmidt, R. E. Willburger

43. CT-Based and CT-Free Navigation with the BrainLAB VectorVision System in Total Knee Arthroplasty

Accurate alignment of knee implants is essential for the success of total knee replacement. Although mechanical alignment guides have been designed to improve alignment accuracy, there are several fundamental limitations of this technology [2]. Petersen and Engh [8] reported radiological results of 50 primary knee arthroplasties. 26% (13/50) failed to achieve a satisfactory post-operative limb alignment (±3°). In several studies the rotational alignment of the femoral component has shown to be crucial for patellofemoral mechanics and balancing of flexion and extension gaps, and a significant correlation was found between patient outcome and prosthesis alignment [1].

L. Perlick, H. Bäthis, C. Lüring, M. Tingart, J. Grifka

44. Extra-Medullary Computer-Assisted Total Knee Replacement: Towards Lesser Invasive Surgery

Modern total knee replacement has emerged as one of the most successful and reproducible surgical procedures performed today [26,41]. Much of this success has been due to the advances made with improved instrumentation with an understanding of the importance of restoring normal alignment of the mechanical axis of the knee [1,12,13,15, 22, 29, 36, 46]. However, even with modern intra-medullary alignment systems there is still variability in the overall results achieved. There is further continued concern about fat embolization with intra-medullary techniques. Computer-assisted extra-medullary techniques offer the opportunity for improved accuracy and reproducibility while avoiding instrumenting the intramedullary canal. As total knee replacement continues to evolve with minimally invasive surgery, the incorporation of computer-assisted techniques has the potential to allow the surgeon to continue to place the knee components accurately with less trauma to the patient.

R. L. Wixson

45. Knee Endoprosthesis Navigation with the Stryker System

Cooperation with industrial navigation developers should be made dependent upon whether these companies are prepared to fulfill medical demands on navigation surgery: Navigation systems should not only be regarded as aids for positioning endoprostheses (electronic spirit levels),but should also provide for intraoperative kine- matic analysis. Particularly in the case of frictional joints such as the shoulder or knee, the analysis of intraoperative kinematics is of far-reaching impor-tance for postoperative function. A reduction of the navigational measurements solely to an alignment of the prosthesis at the same time means a reduction of quality management to the postoperative X-ray image.The development of navigation systems should be organized in such a way that the systems are available to the user as open systems, i.e. the user must be free to choose the design of prosthesis during the operation.A reduction of the software to individual products - possibly those of the developing company - leads to a restriction of the physician’s freedom of action and thus to a disadvantage for the patient. Open systems not only make it possible to freely choose the implant design, but also to check the kinematic qualities of different endoprostheses, to use kinematic navigation systems in prosthesis development and, above all, to determine mal-positioning of the in-situ prosthesis and its abnormal kinematics in revision cases.The development of navigation systems should take into account the economic situation of the health-care institutions. Real-time navigation must be demanded that does not lead to an increase in the costs of indi-vidual treatment due to additive imaging diagnostics and manpower, but also a navigation that appropri- ately exceeds the normal operation times.The development of modern navigation systems should include the possibility of allowing interactive processes between the senders and the central hard- ware. This will make it possible to rapidly build up modules for further joint regions and to change soft-ware in quick development steps, in order to make it even more user-friendly. This will minimize the secondary costs, and interactive processes between the LED and the central computer system will thus enable industrial development work that will rapidly encompass the different regions of the body.

M. Sparmann, B. Wolke

46. Capabilities and Limits of Kinematically Based Navigation Sysytems in Total Knee Arthroplasty

Soft-tissue balancing and geometrically correct positioning with respect to the bony axes both play an equally important role during prosthesis implantation in total knee arthroplasty. The possible presence of ligamentous instabilities, and the thereby resulting incorrect loading of the prosthesis increase the risk of polyethylene wear and early loosening of the prosthesis.

C. Stukenborg-Colsman, C. Hurschler, S. Ostermeier, K. Knabe, H. Windhagen, F. Gossé

47. Fluoroscopy-Based Navigation in Genes II Total Knee Arthroplasty with theMedtronic » Viking «

Mal-alignment reduces the survival of total knee replacements. The imbalance of the soft-tissue results in instability of the replaced knee joint. This leads to functional deficits and increased wear.

F.-W. Hagena, M. Kettrukat, R. M. Christ, M. Hackbart

48. CT-Based Planning and Individual Template Navigation in TKA

Among the various modalities of alloarthroplasty of the knee joint the total endoprosthesis is the most often exe-cuted intervention in the world. Severe arthrosis and axial deformities up to 30º varus or valgus can thereby be equalized. Today’high quality standard of surgical treatment requires anatomically correct orientation and fitting of the implant aiming at optimal biomechanical functionality. Thus, the single components must be taken into account as well as functional changings of tension in the surrounding soft tissue.

F. Portheine, J. A. K. Ohnsorge, E. Schkommodau, K. Radermacher

Unicompartmental Knee Arthroplasty

49. Implantation of Unicondylar Prosthesis Using theOrthoPilotSystem

The unicompartmental knee endoprosthesis (UKP) remains the subject of controversial discussion. Although no one denies that the functional results are better than those for total knee prostheses (TKP) [6], and possibly also than those for valgus corrective osteotomy [9], the long-term results of these implants are still often regarded as unsatisfactory. However, certain authors have reported remarkable results which stand comparison with the best results from total prosthesis implantations [2]. These specially selected series of very experienced centers are confirmed by the results of the Swedish Knee Arthroplasty Register [7], which finds only a minimal difference in the survivor rates after ten years: 88% for the TKPs, 84% for the UKPs. One must try to discover the causes for failure of certain UKA implantations, rather than condemning the principle as such.

J.-Y. Jenny, C. Boeri

Robotics: Total Knee Arthroplasty

50. Clinical Results with the Robot-Assisted ≫CASPAR≪ System and the ≫Search-Evolution Prosthesis≪

The number of Total Knee Arthroplasty (TKA) operations per annum is increasing. This is possibly due to the increasing life expectancy of the older population and their demand for painless mobility. The high life expectancy of people with implants also calls for long-term durability which is to be achieved by an improvement of the implantation techniques.

S. Mai, C. Lörke, W. Siebert

51. Clinical Experiences with ROBODOC and the Duracon Total Knee

A surgical robot (ROBODOC) is used for total knee replacement (◘ Fig. 51–1). The system has been used as clinical routine for total hip replacement at the Trauma Clinic of Trade Associations (BGU) Frankfurt, Germany since 1994. Since March 2000 it has also been used for total knee arthroplasty.

M. Börner, U. Wiesel, W. Ditzen

24. Total Knee Arthroplasty

Knee replacements have evolved from the single-axis fixed-hinge devices of the 1950’s (Walduis, Shiers) [23] to the unlinked fixed-axis devices of the 1960’s (Geomedic, Polycentric) [3,13], both of which had a limited clinical use because of loosening and wear problems.

F. F. Buechel, J. B. Stiehl

25. Why the Tibia Cut First in Mobile Bearing TKA Technique?

There are three major objectives of surgical technique in total arthroplasty. First is the need to achieve anatomical alignment of 5° to 7° valgus angulation to the mechanical axis. Second is to establish ligamentous balance by achieving careful balance of the flexion and extension gaps within 2 to 3 millimeters of physiological. Finally, is the desire to optimize the potential kinematics of the chosen prosthetic implant. The ≫Tibial Cut First≪ technique follows the original idea of Dr John Insall that establishing the flexion gap was the most important variable in successful total condylar arthroplasty [1] .We will discuss why this approach has become an attractive surgical technique for mobile bearing total knee arthroplasty and how surgical navigation will more accurately place the proximal tibial cut in total knee arthroplasty.

J. B. Stiehl

26. Surgical Techniques

Unquestionably, the era of modern total knee replacement commenced with the production of the Polycentric Knee Prosthesis designed by John Gunston of Canada, in the late 1960’s. This prosthesis was soon followed by the Geomedic Knee developed by a design team of five by the prosthesis manufacturer Howmedica. Both prostheses incorporated the technology pioneered by John Charnley in the U.K., combining methylmethacrylate bone cement with cobalt chrome alloy or adequate stainless steel.

K.A Krackow

27. Femoral Component Alignment in TKA

Femoral rotation positioning is critical for successful total knee arthroplasty (TKA). There are three generally accepted methods of referencing femoral component rotational alignment. These include the transepicondylar axis (TEA), as advocated by Insall, arbitrary external rotation from the posterior condyles, and the so-called Whiteside line. Another less well recognized method, which has been used for over 25 years, is referencing femoral component rotation perpendicular to the tibial shaft axis via a balanced flexion tension gap. Placing the femoral component parallel to the TEA leads to a bio-mechanically sound knee motion in full flexion and extension. However, this method has potential errors that include any anatomical deviations of the distal femur, which may occur in cases with severe varus or valgus angle deformity, condylar dysplasia, or other rotational pathology of the lower extremity.

J. G. Boldt

28. Computer-Assisted Ligament Balancing of the Femoral Tibial Joint Using Pressures Sensors

Premature wear of the ultra-high molecular weight polyethylene (UHMWPE) tibial insert has been implicated in total knee arthroplasty (TKA) failure [6,7]. Several variables are thought to contribute to polyethylene wear including patient factors, implant design, and surgical technique. While the factors in implant design that optimize implant longevity (such as large contact areas and high conformity) have been defined and implemented, surgical technique has been more difficult to quantitatively evaluate, because it remains more subjective and surgeon-dependent. Therefore, advances in surgical technique that lead to improved implant longevity have been difficult to define.

R. C. Wasielewski, D. D. Galat, R. D. Komistek

29. Computer-Assisted Pressure Measurement in the Patellofemoral Joint with Electronic Pressure Sensors

The patella forms a sesamoid bone in the quadriceps muscle. It has different functions. Apart from force conduction and forming a lever arm for the quadriceps muscle it influences the friction coefficient between quadriceps and femur. A missing patella is last cut not least noted cosmetically. The first developed knee endoprostheses considered the patella only on a peripheral base. Follow-up studies of total knee replacements showed the peripatellar region to be of importance in approximately 10% of the patients complaining about problems [1,2,5,7,16,18,20,28,34]. Surgical indication, surgeon and type of endoprosthesis influence the decision for or against patellar replacement during total knee replacement (TKR). Major problems of the patellofemoral region are pain, lateralizing of the patella and rarely soft tissue impingement, patellar fractures and patellar loosening. Literature shows supporters for [6,21,26,29,33] as well as opponents against patellar replacement [3,9,22].

J. Mortier, L. Zichner

30. Patellofemoral Arthroplasty

Patellofemoral osteoarthritis is well known by all orthopaedics surgeons. Its expression is variable, from anterior knee pain to classic femoropatellar syndrome when sitting or climbing down stairs. Non-operative treatment is probably the first option to select including medical treatment and physiotherapy. However, non-operative treatment is sometimes insufficient and different surgical techniques can be proposed. These techniques include the articular arthroscopic washing or the section of the lateral retinacular of the patella which efficacy is still debated particulary in the long term despite the low morbidity of arthroscopy. The Maquet procedure [37] (anterior tibial tuberosity advancement), the microperforation of the patella (Pridie procedure) or all kinds of plasty are more invasive techniques, with inconsistent results [24].

James B. Stiehl, Werner H. Konermann, Rolf G. Haaker

Navigation and Robotics: Anterior Cruciate Ligament (ACL) Reconstruction


52. Fundamentals in ACL Reconstruction: ≫The American View≪

In ACL reconstruction procedures, the position of femoral and tibial tunnels is known to significantly affect the clinical outcome. Despite this knowledge however, great variability exists in tunnel placement among surgeons and the rate of misplaced tunnels in ACL reconstruction surgery has been reported between 10–40% [13, 16]. The result of misplacement of tunnels as well as a number of other reasons is revision ACL reconstruction [9]. Surgeons frequently use preoperative radiographs during surgery to assist with tunnel placement, however no direct links exist to the intraoperative situation. Computer-assisted surgery (CAS) is now assumed to help improve precision in ACL reconstruction and to provide this link. This manuscript will review fundamentals of ACL reconstruction and briefly discuss the different available CAS systems.

V. Musahl, F. H. Fu

53. Fundamentals in ACL Reconstruction: ≫The European View≪

Tears of the anterior cruciate ligament are common in¬juries. Today the incidence is 1 injury per 1000 people per year [102]. It occurs typically during sports due to a external rotation valgus movement of the flexed weight bearing knee e.g. during skiing or football. An overextension mechanism is also possible.

S. Rupp, D. Kohn

54. Image-Free Navigation in ACL Replacement with the OrthoPilot System

In many areas of surgery, ever smaller approaches are being sought to reduce soft tissue traumatisation in minimally invasive operating techniques. This is associated with the danger that the surgeon will lose an overview of the topography of the structures as a whole. Computer-assisted navigation promises to remedy this. Computer-assisted surgery began in the 1990s with intracranial neurosurgical operations and the implantation of pedicle screws in spinal surgery, using CT and MRI imaging. Today however, there are other solutions which do not require pre- and intraoperative X-rays. One of these solutions is offered by the OrthoPilot navigation system (⊡Fig. 54-1).

H.-J. Eichhorn

55. Clinical Experiences for ACL-Repair with the SuriGATE System

Navigation in orthopaedic surgery is often associated with the experimental environment of a university hospital. However, in our experience, the practical set-up is more frequently performed in regional hospitals.

J. De Rycke

56. Clinical Experience Using the SurgiGATE System

Anterior cruciate ligament (ACL) reconstruction occurs most commonly in the young and active patient 13,10,20]. The frequency of ACL injuries has increased because recreational activities and more risky sports became very popular. Frank and Jackson reported of 50,000 ACL reconstructions per annum in the USA in 1997. With the introduction of less invasive arthroscopic surgery in the 80s and 90s,ACL surgery is generally considered as a procedure with little risks. Open knee surgery becomes a method of the past lowering problems such as reduced proprioception and stability. When treated conservatively, knee joint instability after ACL tears has to be considered as a pre-arthritic condition leading to considerable cartilage and meniscus degeneration as reported by Schippinger et al. [18]. In a large follow-up study McDaniel and Dameron [12] recognized degenerative radiographic changes in over 8o% of conservatively treated ACL injuries. Sutures of torn ACL show frustrating results with regards to blood supply and knee joint stability.

M. Wiese, A. Rosenthal, K. Bernsmann

57. ACL Surgetics: An Efficient Computer-Assisted Technique for ACL Reconstruction

Anterior cruciate ligament (ACL) rupture has become one of the most common knee injuries. Various surgical techniques have been proposed for its reconstruction, and one of the main difficulties is to determine an accurate placement of the ligament substitute, which has a predominant influence on the ACL reconstruction longevity [2,8]. According to some publications, the rate of incorrectly placed ACL reconstructions may be as high as 40%. Thus, in a study performed in 24 cadaver knees, the results of the ACL grafts placements, only 4 of 24 were found to be correctly positioned [11]. This underlines the importance of graft placement at the anatomical insertion points of the native ACL. To meet this complex and challenging requirement, both technical points and anatomical features will need to be taken into consideration.

R. Julliard, S. Plaweski, S. Lavallée

58. Clinical Experience with CASPAR-Asissted ACL Reconstruction

The causes and reasons for unsatisfactory results and failures after replacement of the anterior cruciate ligament (ACL) are numerous and diverse. However, irrespective of what material is used for replacement, the incorrect position of the transplant plays the leading role. According to the consensus conference of the International Knee Society, more than 40% of all ACL transplants are incorrectly positioned. It has been documented many times in the literature that there is a close correlation between the position of a transplant and the clinical outcome [e.g. 1,5–8]. Revision operations after ACL reconstruction are based on transplant mal-positioning in 70% to 80% [loc.cit.9].

L. Gotzen, A. Pashmineh-Azar, E. Ziring

59. ACL-Reconstruction with the Navitrack System

Critical Analysis of Navigation in ACL-Surgery

Decisive for successful surgical stabilization of the knee-joint following rupture of the anterior cruciate ligament is the correct anatomical positioning of the cruciate-ligament graft. Even though anatomically the differentiation is made between an anteromedial and a posterolateral fascicle and there is thus a superficial insertion onto the femur and the tibia, there is however a general consensus regarding the position of the tibial and femoral insertion points and of the drilled tunnels for the reconstruction of the anterior cruciate ligament [4,7,13].

A. Ellermann, R. Siebold

Navigation: Pelvic and Lower Extremity


60. High Tibial Osteotomy – Use of Navigation System

In patients suffering from gonarthrosis, which is limited to the medial aspect of the knee joint, high tibial valgisation osteotomy appears to be an appropriate alternative to knee arthroplasty [6,9]. In 1958, Jackson described this procedure for axis correction of the proximal tibia [8] for the first time. This operation was modified 1965 by Coventry [3]. At first, it was used mainly for correction of valgus deformities. According to the knee baseline in valgus deformity, distal femur osteotomy may be recommended [1]. For a long time the indication for high tibial osteotomy was not subject to discussion [2]. Within the last years high tibial osteotomy was performed more and more seldom and seemed to be replaced by uni- or bicondulary knee arthroplasty. Taking into account the biomechanical basics and the very positive long-time results, which were achieved by the traditional osteotomy technique this change of treatment does not seem to be adequate.

J. Hassenpflug, M. Prymka

61. Navigated Correction Operations of the Pelvis

Nonunions or clinical relevant posttraumatic malunions of the pelvis are rare entities due to the application of standardized treatment protocols. However, also with an optimal primary treatment these problems may occur [8,10].

T. Hüfner, J. Geerling, U. Berlemann, T. Pohlemann, T. Gösling, A. Scott, C. Krettek

62. Computer-Based Drilling of Osteochondral Lessions of the Talus (OLT) with an Aiming Device

The complex anatomic location and the resulting difficult access path often causes problems in surgical treatment of symptomatic osteochondral talus lesions (OLTs) [13, 17]. While anterolateral lesions are amenable to arthroscopic treatment, those located dorsomedially are much less accessible arthroscopically [7,18]. In open surgical interventions, these lesions are only accessible via osteotomy of the inner malleolus. Although arthroscopic and open surgical interventions differ in detail, the underlying principle of therapy is very similar [12]. On the one hand they consist of debriding the chondritic part, on the other hand they support and promote revascularization of the necrotic bony areas by for example drilling into the subchondral zone. Direct anterograde drilling of osteochondral lesions, however, is sometimes technically impossible, true especially for the dorsomedially located lesions. Transmalleolar drilling [20] or the use of curved drill bits [6] have been described as a possible approach. However, a disadvantage of anterograde drill techniques is that, should the chondral surface over the lesions still be intact, it gets damaged. The transmalleolar drill technique also damages the malleolar joint cartilage [16].

R. E. Rosenberger, C. Hoser, C. Fink, R. J. Bale

63. Computer-Assisted Osteosynthesis of Long Bone Fractures

Image intensifiers (C arms) are the most common and most used medical device for image acquisition in the trauma operating room. The image intensifier is an important device for intraoperative diagnosis of results of actual fracture reductions, for monitoring the actual position of surgical instruments drill bits, and also for checking the correct position of materials for an osteosynthesis, and of other implants. In the last decades, techniques in trauma surgery have changed tremendously. In former times, fractures were treated with large incisions and stabilized with plates in similar dimensions. Today we know that the technique of minimally invasive osteosynthesis, with a reduction of the trauma by minimizing the incision and the related soft-tissue damage, is an essential benefit for the patient, not only because of the cosmetic result but also for speed of recovery and functional results.

P. A. Grützner, G. Zheng, B. Vock, C. Keil, L. P. Nolte, A. Wentzensen

64. Pelvic Osteotomy with Template Navigation

Various surgical techniques are used for the treatment of hip dysplasia in young people and adults. In contrast to acetabuloplasty in children, the position of the complete acetabulum is corrected. The repositioning serves to enlarge the weight bearing zone of the dysplastic acetabulum covering the femoral head, in order to reduce pressure on this area to physiological levels. The major goals of this therapy are relief from pain as well as preventing premature osteoarthritis with the necessity for artificial hip replacement. The basics of the biomechanics as well as diagnosis and indications are described and discussed in detail elsewhere [9,11]. Apart from the triple osteotomy according to Tönnis, practiced by our clinic since more than 15 years, particular mention should be made of the periacetabular osteotomy technique described by Ganz [3]. In contrast, the spherical osteotomy procedure of Wagner [12] has not become established due to the danger of acetabular necrosis.

H.-W. Staudte, E. Schkommodau, M. Honscha, F. Portheine, K. Radermacher

Navigation: Spinal Surgery


65. Fundamentals in Spinal Surgery

The past thirty years have seen an evolution of spine surgery from limited decompressive procedures to extensive spinal reconstruction, involving multilevel decompressions, fusions, and instrumentation. With a better understanding of spinal anatomy, pathology and the biomechanics of the spine and instrumentation systems, surgical options in the spine are constantly growing. The aim of this chapter is to review the essential concepts in spine surgery, and evaluate conventional surgical techniques.

R. Rao, M. Singrakhia

66. Navigation in Cervical Spine Surgery

In general there is no difference in stabilization techniques of the cervical spine compared with the lumbar spine: screws are inserted into the spine and connected with rods (posterior) and a plate (anterior) to achieve primary stability. Transarticular screw fixation is introduced by Magerl for C1/C2. Judet described another fixation technique for fracture of the pars interarticularis of C2 in which a screw bridges the both fracture parts.

A. Weldner

67. Pedicle Screw Placement

During the last two decades transpedicular fixation systems became standard for stabilization in thoracal and lumbar spine surgery [15]. For example, the number of fusions operations, especially for lumbar and lumbosacral degenerative diseases, has increased during that period [36]. In trauma spine surgery it is common to use these implants as well. In a multicenter study of the ≫Spine Study Group≪ of the German Trauma Society, the posterior instrumentation is the standard procedure in vertebral fractures of the thoracic and lumbar spine [25].

J. Geerling, U. Berlemann, B. Frericks, M. Kfuri, T. Hüfner, C. Krettek

68. Navigation in Spinal Surgery Using Flouroscopy

Since popularized by Roy Camille [22], pedicle screws are widely used in combination with rods or plates (internal fixator) for spinal fixation in different conditions because of the biomechanical superiority of this construct [15,27]. Furthermore, higher fusion rates are reported with the use of an internal fixator [3,28].

E. W. Fritsch

69. Navigation of Tumor and Metastatic Lesions in the Thoracolumbar Spine

Since the description of transpedicle fixation of posterior spinal implants by Roy-Camille et al. [18], this procedure has gained general acceptance for rigid segmental fixation. Correct implantation of the screws without perforation of the pedicle is difficult and requires detailed anatomic knowledge and good surgical skills. The identification of the correct entry point for the pedicle screw and the correct angle of inclination in the sagittal and transverse planes are crucial. A standard technique for pedicle screw insertion is done with an image intensifier in the lateral and anteroposterior (a.p.) views. In osteolytic tumors identification of anatomical landmarks is difficult and intraoperative imaging can be impossible due to increased radio translucent vertebrae.

F. Gebhard, M. Arand

70. Pedicle Screw Implantation Using the DISOS Template System

In computer-aided pedicle-screw implantation, exactly as in conventional procedures, correct positioning of the screw is only possible based on a precise knowledge of the anatomical structure in question. The choice of screw length and caliber depends to a great extent on detailed knowledge about this structure [6]. Generally, the greater the screw length and caliber, the better the anchoring [4]. In addition, particular attention must be paid to ventral boundaries and the constant danger of perforation in the area of the spinal cord. The proximity of the spinal column means the greatest care is required in introducing the screw in order to avoid damage to surrounding neural and vascular structures. Placement of a pedicle screw is therefore difficult since there is no direct view into the spine. In particular, problems can arise with medial or caudal placement of the screw, possibly resulting in serious neurological dysfunction. In the literature, faulty placements (perforations) using conventional procedures are reported to range from between 8.5% [2], 15.9% [9], 39.9% [3], and 42% [5].

E. Schkommodau, N. Decker, U. Klapper, K. Birnbaum, H.-W. Staudte, K. Radermacher

Visions of Surgeons


71. Navigation —Where do we go from here?

Trying to predict the future of a quickly developing domain such as navigational surgery always bares a certain risk. One easily faces the danger of wrongly estimating current trends and developments, and within in a few years being proven as wrong as Thomas Watson, the former chairman of IBM. In 1943, Mr. Watson was convinced that ≫there is a potential for maybe five computers worldwide≪. Nevertheless, we can look back at almost 10 years of computer-assisted orthopaedic surgery and identify a number of weak points which still exist. We can observe numerous concepts and ideas that have recently been developed for, or are currently being introduced into CAOS. These observations surely suggest certain directions for speculation about what the future of CAOS may be. Conjuring up science fiction will definitely not be the goal of this chapter, since such forecasts often turn out to remain ≫visions≪ even after 10 or 20 years, but rather an overview shall be provided that estimates which developments may become reality within the next years and will be usable in the OR on a routine basis.

F. Langlotz

72. The Asian Knee -Is Navigation Possible?

While primary osteoarthritis of the hip is rare, primary osteoarthritis of the knee is relatively common in the Asian populations [4]. The exact reason remains unclear, but it could be due to different mechanical environment in the Asian knees [12,13]. Despite knee osteoarthritis is common, the Asian patients did not like surgery. They preferred to live with the pain, frequently at the expense of the daily activities. The view points have changed in the past 5 to 10 years, and more patients now demand for active lives despite of old age. In many Asian countries, the frequency of total knee arthroplasties (TKAs) has been rising constantly. In some places, TKAs have become significantly more common than total hip arthroplasties in the ratio of 2 or 3 knees to 1 hip, or even higher.

K. Y. Chiu

73. Status Quo and Options in Medical Robotics

≫Where humans can’t go, they build robots.≪ This principle is common practice in space science and nuclear power engineering as demonstrated i.e. with remote cars on planet Mars or robots working on nuclear substances steered by humans located behind protecting glass.

M. Börner, W. Ditzen

Visions of the Industry


74. Evolution of Navigation: The Operating Room in the Year 2012

There are many visions of what the operating theater will be like in a decade’s time. Keywords such as robotics, telemanipulation, multimodality, or intraoperative imaging are terms which crop up again and again in this connection. The patient appears to retreat into the background as more and more complex technology moves into the operating theatre.

H.-P. Tümmler

75. Joint and Spinal Surgery 2005

In our capacity as a solutions provider, Siemens Medical Solutions analyzes the workflow of our customers and seeks to optimize it to achieve greater quality, efficiency and cost effectiveness. We provide our customers with the information and tools needed to obtain an economical solution from diagnosis to treatment planning, to the treatment itself and aftercare.

A. Steiner, J. Hey

76. Computer-Guided Navigation in Orthopaedic Surgery

Software-guided medical technology has conquered the modern operating room, and many fields of medicine are hard to imagine without it today. Innovative medical technology makes it possible to perform complex surgical operations with a higher degree of safety and lower risks for patients. Modern computer systems, for instance, allow precision radiation of tumors and blood clots. BrainLAB AG develops and distributes software-based medical solutions to ease the work of doctors around the world. The company first made a name for itself in the fields of neurosurgery and the radio therapeutic treatment of brain tumors - as the name suggests - and has become the international market leader in these fields. Now, with the close cooperation of doctors specializing in different fields, BrainLAB has expanded its product range to include solutions in the field of ENT, where it supports, among other things, sinus surgery, and in orthopaedics, where it is used especially for hip and knee replacement surgery. Describing the company’s future plans, Stefan Vilsmeier, founder and CEO of BrainLAB AG, explains, ≫Cooperating with doctors and implant manufacturers, we will continue to push the development and establishment of minimally invasive technologies, such as computer-assisted surgery, to offer patients new treatment options that improve medical outcome and entail lower risks and side effects.≪

S. Christmann

77. Planning, Navigation and Robotics in Orthopaedic Surgery

Computer-aided surgery techniques are successfully applied in neuro- and spinal surgery for several years. Now, there is a tendency for digital planning software and navigation systems to become standard clinical equipment for endoprosthetic surgery, too. But for further establishment of these new electronic devices, it is strongly required that existing and proved clinical practice in the OR has to be considered. Not everything technically possible is clinically useful.

R. Nassutt

78. Computer-Assisted Operational Techniques from the Perspective of a System and Implant Manufacturer

No other technology in the field of orthopaedics and traumatology can match the success of computer-assisted operational procedures over the last ten years. This has been achieved thanks to advances in industrial measurement techniques and robot technology. The obvious potential of these technologies for increasing safety and accuracy in surgery has yielded a range of products for the active and passive support of orthopaedic and traumatology surgery. For example, the implant manufacturer Precision Implants AG/PI Systems, the development and production centre of the companies PLUS Endoprothetik and Intraplant, exploited its existing know-how and developed the PiGalileo navigation and robot system using industrial measurement technology. A small robot, the PiGalileo CAS, was the first product developed. It was a two-axis system for knee endoprostheses controlled by a laptop computer and was based on the large robots used in industry, with adaptation for a sterile environment. The cost of this equipment, without navigational support, was about the same as the equipment and instruments used to carry out conventional knee prosthesis and allowed the technology to be accessible to a large area of application (◘Fig. 78–1).

W. Moser

79. How Much Technology is Needed in the Operating Room?

It is not long ago that personal digital assistants replaced organizers of the traveling businessman. Not just the recently added functionality like telephony, wireless communication, etc. but its seamless integration into powerful applications is what truly enabled the mobile warrior to enhance his productivity. Typical multi-tasking activities involve now for instance voice activation through a wireless headset, instant messaging and data processing on web-supported applications on one and the same handheld device.

J. L. Moctezuma de la Barrera, D. Malackowski


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