Computer assisted orthopaedic and trauma surgery. State of the art and future perspectives

Automatic Registration and Error Color Maps to Improve Accuracy for Navigated Bone Tumor Surgery Using Intraoperative Cone-Beam CT

Computer-assisted surgery (CAS) can improve surgical precision in orthopaedic oncology. Accurate alignment of the patient’s imaging coordinates with the anatomy, known as registration, is one of the most challenging aspects of CAS and can be associated with substantial error. Using intraoperative, on-the-table, cone-beam computed tomography (CBCT), we performed a pilot clinical study to validate a method for automatic intraoperative registration.

The role of imaging in computer assisted tumor surgery of the sacrum and pelvis

The use of a navigation system allows precise resection of a tumor and accurate reconstruction of the resultant defect thereby sparing important anatomical structures and preserving function. It is an "image-based" system where the imaging (computed tomography and magnetic resonance imaging) is required to supply the software with data. The fusion of the preoperative imaging provides pre-operative information about local anatomy and extent of the tumor, so that it allows an accurate preoperative planning. Accurate pre-operative imaging is mandatory in order to minimize CATS errors, thus performing accurate tumor resections.

Influence of multi-angle input of intraoperative fluoroscopic images on the spatial positioning accuracy of the C-arm calibration-based algorithm of a CAOS system

Intraoperative fluoroscopic images, as one of the most important input data for computer-assisted orthopedic surgery (CAOS) systems, have a significant influence on the positioning accuracy of CAOS system. In this study, we proposed to use multi-angle intraoperative fluoroscopy images as input based on real clinical scenario, and the aim was to analyze the positioning accuracy and the error propagation rules with multi-angle input images compared with traditional two input images. In the experiment, the positioning accuracy of the C-arm calibration-based algorithm was studied, respectively, using two, three, four, five, and six intraoperative fluoroscopic images as input data. Moreover, the error propagation rules of the positioning error were analyzed by the Monte Carlo method. The experiment result showed that increasing the number of multi-angle input fluoroscopic images could reduce the positioning error of CAOS system, which has dropped from 1.01 to 0.61 mm. The Monte Carlo simulation analysis showed that for random input errors subject to normal distribution (μ = 0, σ = 1), the image positioning error dropped from 0.29 to 0.23 mm, and the staff gauge positioning error dropped from 1.36 to 1.19 mm, while the tracking device positioning error dropped from 3.41 to 2.13 mm. In addition, the results showed that image positioning error and staff gauge positioning error were all nonlinear error for the whole system, but tracker device positioning error was a strictly linear error. In conclusion, using multi-angle fluoroscopy images was helpful for clinic, which could improve the positioning accuracy of the CAOS system by nearly 30%. Graphical abstract The experiment process and Monte Carlo analysis of spatial positioning accuracy (A: Setup for the experiment; B: The process of Monte Carlo analysis; C: Results).

3D Ultrasound for Orthopedic Interventions

Ultrasound is a real-time, non-radiation-based imaging modality with an ability to acquire two-dimensional (2D) and three-dimensional (3D) data. Due to these capabilities, research has been carried out in order to incorporate it as an intraoperative imaging modality for various orthopedic surgery procedures. However, high levels of noise, different imaging artifacts, and bone surfaces appearing blurred with several mm in thickness have prohibited the widespread use of ultrasound as a standard of care imaging modality in orthopedics. In this chapter, we provided a detailed overview of numerous applications of 3D ultrasound in the domain of orthopedic surgery. Specifically, we discuss the advantages and disadvantages of methods proposed for segmentation and enhancement of bone ultrasound data and the successful application of these methods in clinical domain. Finally, a number of challenges are identified which need to be overcome in order for ultrasound to become a preferred imaging modality in orthopedics.

Patient-specific core decompression surgery for early-stage ischemic necrosis of the femoral head

Introduction

Core decompression is an efficient treatment for early stage ischemic necrosis of the femoral head. In conventional procedures, the pre-operative X-ray only shows one plane of the ischemic area, which often results in inaccurate drilling. This paper introduces a new method that uses computer-assisted technology and rapid prototyping to enhance drilling accuracy during core decompression surgeries and presents a validation study of cadaveric tests.

Methods

Twelve cadaveric human femurs were used to simulate early-stage ischemic necrosis. The core decompression target at the anterolateral femoral head was simulated using an embedded glass ball (target). Three positioning Kirschner wires were drilled into the top and bottom of the large rotor. The specimen was then subjected to computed tomography (CT). A CT image of the specimen was imported into the Mimics software to construct a three-dimensional model including the target. The best core decompression channel was then designed using the 3D model. A navigational template for the specimen was designed using the Pro/E software and manufactured by rapid prototyping technology to guide the drilling channel. The specimen-specific navigation template was installed on the specimen using positioning Kirschner wires. Drilling was performed using a guide needle through the guiding hole on the templates. The distance between the end point of the guide needle and the target was measured to validate the patient-specific surgical accuracy.

Results

The average distance between the tip of the guide needle drilled through the guiding template and the target was 1.92±0.071 mm.

Conclusions

Core decompression using a computer-rapid prototyping template is a reliable and accurate technique that could provide a new method of precision decompression for early-stage ischemic necrosis.

Computer-assisted Orthopaedic Surgery

Nowadays, operating rooms can be inefficient and overcrowded. Patient data and images are at times not well integrated and displayed in a timely fashion. This lack of coordination may cause further reductions in efficiency, jeopardize patient safety, and increase costs. Fortunately, technology has much to offer the surgical disciplines and the ongoing and recent operating room innovations have advanced preoperative planning and surgical procedures by providing visual, navigational, and mechanical computerized assistance. The field of computer-assisted surgery (CAS) broadly refers to surgical interface between surgeons and machines. It is also part of the ongoing initiatives to move away from invasive to less invasive or even noninvasive procedures. CAS can be applied preoperatively, intraoperatively, and/or postoperatively to improve the outcome of orthopaedic surgical procedures as it has the potential for greater precision, control, and flexibility in carrying out surgical tasks, and enables much better visualization of the operating field than conventional methods have afforded. CAS is an active research discipline, which brings together orthopaedic practitioners with traditional technical disciplines such as engineering, computer science, and robotics. However, to achieve the best outcomes, teamwork, open communication, and willingness to adapt and adopt new skills and processes are critical. Because of the relatively short time period over which CAS has developed, long-term follow-up studies have not yet been possible. Consequently, this review aims to outline current CAS applications, limitations, and promising future developments that will continue to impact the operating room (OR) environment and the OR in the future, particularly within orthopedic and spine surgery.

Intraoperative 3-Dimensional Computed Tomography and Navigation in Foot and Ankle Surgery

Computer-assisted orthopedic surgery has developed dramatically during the past 2 decades. This article describes the use of intraoperative 3-dimensional computed tomography and navigation in foot and ankle surgery. Traditional imaging based on serial radiography or C-arm-based fluoroscopy does not provide simultaneous real-time 3-dimensional imaging, and thus leads to suboptimal visualization and guidance. Three-dimensional computed tomography allows for accurate intraoperative visualization of the position of bones and/or navigation implants. Such imaging and navigation helps to further reduce intraoperative complications, leads to improved surgical outcomes, and may become the gold standard in foot and ankle surgery. [Orthopedics.2016; 39(5):e1005-e1010.].

Assessment of registration accuracy during computer-aided oncologic limb-salvage surgery

PURPOSE

Computer-aided surgery is used in musculoskeletal tumor procedures to improve the surgeon's orientation to local anatomy during tumor resection. For the navigation system to function correctly, preoperative imaging (e.g., CT, MR) must be registered to the patient in the operating room. The goals of this study were (1) to directly quantify registration accuracy in computer-aided tumor surgery and (2) to validate the "system reported error" (SRE) of the navigation system.

METHODS

Registration accuracy was evaluated in eight bone sarcoma cases by determining the location of the anatomical paired-points used for registration following surface matching. Coordinates of specific intraoperative post-registration points were compared with the corresponding coordinates in preoperative CT scans to determine the measurement error (ME).

RESULTS

The mean difference between post-registration points and planned registration points was 12.21±6.52 mm significantly higher than the mean SRE (0.68 ± 0.15 mm; p = 0.002; 95 % CI 6.11-16.96 mm). The SRE poorly correlated with the calculated ME (R(2) = 0.040). Anatomical paired-point registration with surface matching results in a substantial shift in the post-registration coordinates of the same paired-points used for registration, and this shift is not represented by the SRE.

CONCLUSION

The SRE of a surgical navigation system was poorly correlated with direct measurements obtained in musculoskeletal tumor surgery. Improvement in registration accuracy is needed to better navigate tumor boundaries and ensure clear margins while maximally preserving the unaffected tissues and reducing operative morbidity.

Three-dimensional fluoroscopy-navigated percutaneous screw fixation of acetabular fractures

OBJECTIVE

Anatomic reduction and articular restoration after acetabular fractures occur (Ac-Fxs) are accepted predictors for good function and slow progression of posttraumatic osteoarthritis of the hip. The aim of this study was to retrospectively analyze Ac-Fxs, which were treated with closed reduction and percutaneous (three-dimensional) fluoroscopy-based navigated screw fixation.

DESIGN

Level 4, retrospective clinical and radiographic assessment.

SETTING

Level 1 trauma center.

PATIENTS

Twelve patients (male/female: 9/3; mean age: 60 years; range: 16-80 years) with moderately displaced Ac-Fxs were included.

INTERVENTION

In enrolled patients, the treatment involved percutaneous three-dimensional fluoroscopy-based navigated lag screw positioning. Closed reduction was achieved by lag screws, or reduction was aided by the insertion of percutaneous Schanz pins.

MAIN OUTCOME MEASUREMENTS

The quality of the reduction and screw positions were assessed using intraoperative and postoperative computed tomography scans. Functional outcome was assessed using the Harris hip score, the visual analog scale for pain, and the Tegener activity scale.

RESULTS

A total of 22 periacetabular screws were placed (mean: 1.8 ± 1.1 screws/patient, range: 1-5). The mean follow-up was done for 30 (16-72) months. The postoperative reduction was anatomical in all patients, and the mean fracture displacement was significantly reduced (gap: 4.1 ± 1.8 mm to 0.4 ± 0.7 mm/step: 1.4 ± 0.6 mm to 0.2 ± 0.4 mm). No secondary dislocations or malunions/nonunions were found. All screws correctly addressed the fracture morphology and corresponded to preoperative planning. The Harris hip score, the visual analog scale (motion), and Tegener activity scale showed excellent to very good results (92.4 ± 6.8, 1.9 ± 1.3, and 3.8 ± 1.6, respectively).

CONCLUSIONS

The navigated, percutaneous screw fixation of selected Ac-Fxs is a promising method that allows for closed reduction and fixation while obtaining a very good radiographic and functional outcome.

LEVEL OF EVIDENCE

Therapeutic level 4.

Guided pedicle screw insertion: techniques and training

BACKGROUND CONTEXT

In spinal fusion surgery, the accuracy with which screws are inserted in the pedicle has a direct effect on the surgical outcome. Accurate placement generally involves considerable judgmental skills that have been developed through a lengthy training process. Because the impact of misaligning one or more pedicle screws can directly affect patient safety, a number of navigational and trajectory verification approaches have been described and evaluated in the literature to provide some degree of guidance to the surgeon.

PURPOSE

To provide a concise review to justify the need and explore the current state of developing navigational or trajectory verification techniques for ensuring proper pedicle screw insertion along with simulation methods for better educating the surgical trainees.

STUDY DESIGN

Recent literature review.

METHODS

To justify the need to develop new methods for optimizing pedicle screw paths, we first reviewed some of the recent publications relating to the statistical outcomes for different types of navigation along with the conventional freehand (unassisted) screw insertion. Second, because of the importance of providing improved training in the skill of accurate screw insertion, the training aspects of relevant techniques are considered. The third part is devoted to the description of specific navigational assist methods or trajectory verification techniques and these include computer-assisted navigation, three-dimensional simulations, and also electric impedance and optical and ultrasonic image-guided methods.

CONCLUSIONS

This article presents an overview of the need and the current status of the guidance methods available for improving the surgical outcomes in spinal fusion procedures. It also describes educational aids that have the potential for reducing the training process.

Research status and application prospects of digital technology in orthopaedics

In the last 10 years, basic and clinical research in orthopaedics has developed rapidly. Understanding of orthopaedic disorders involves not only routine diagnosis, but also the pursuit of highly efficient and accurate three-dimensional imaging of the intra- and extra-medullary distribution, form and structure of orthopaedic disorders, thus allowing scientific evaluation of the indications for surgery, drawing up of the best surgical plan, minimization of operative trauma and the earliest possible restoration of limb function. Meanwhile, the most important type of basic research, which was previously biomechanical research, has gradually become computational biomechanics based on in vitro cadaver experiments. This review aims to summarize the research status and application prospects of digital technology in orthopaedics, including virtual reality technology, reverse engineering and rapid prototyping techniques, computational biomechanics, computer navigation technology and management of digitization of medical records.

Image guidance can support scaphoid K-wire insertion: an experimental study and initial clinical experience

PURPOSE

In the treatment of small bone fractures, such as the scaphoid bone, conventional navigation is limited by its dependence on fixed reference arrays. We introduce a new technique based on reference markers in surgical instruments. If visible on a standard fluoroscopic image, static trajectories are overlaid in this image to guide implant insertions. Fixed markers are not required. The purpose of this study was to identify the possible advantages of the new guidance technique.

METHODS

For this study, 20 artificial hand specimens were randomized into two groups and blinded with polyurethane foam: 10 were treated conventionally and 10 were image guided. We used a clip containing radiopaque markers, which was detected by the system's workstation. A static trajectory was displayed consecutively in the fluoroscopic image to serve as an aiming device. Secondly, we included 3 patients with fractures of the scaphoid bone to test the integrability of this novel method in a clinical setting.

RESULTS

In the experimental setup, trajectory guidance reduced the duration of surgery and radiation exposure. Furthermore, it reduced the perforation rate. Accuracy was not improved by the new technique. For clinical cases, the system was integrated into the accommodated surgical workflow and rated as very helpful by users.

CONCLUSION

The system helped reduce the misplacement rate and the emission of radiation. The main limitations were that trajectories were not displayed in real time and could only be shown in a single fluoroscopic image. However, the system is simple and can be easily integrated into the surgical workflow.

Current state of computer-assisted trauma surgery

Computer assisted surgery (CAS) was first used in neurosurgery. Currently, CAS has gained popularity in several surgical disciplines including urology and abdominal surgery. In trauma and orthopaedic surgery, computer assisted systems are used for fracture reduction, planning and positioning of implants as well as the accurate implantation of hip and knee prostheses. The patient's anatomy is virtualized and the surgical instruments integrated into the digitized image background, thus allowing the surgeon to navigate the surgical instruments and the bone in an improved, virtual visual environment. CAS improves overall accuracy, reducing intraoperative radiation exposure and minimizing unnecessary surgical dissection combined with increased patient and surgeon safety. However, limitations include prolonged surgical time, technical errors and cost implications. This article will outline the current state of computer assisted trauma surgery including its implications and specific challenges in orthopaedic trauma surgery.

Navigation-guided correction of midfacial post-traumatic deformities (Shanghai experience with 40 cases)

PURPOSE

To evaluate the effectiveness of navigation-guided surgical correction as the treatment of midfacial post-traumatic deformities.

PATIENTS AND METHODS

A total of 40 patients with midfacial post-traumatic deformities from 2007 to 2010 were involved in the present study. The preoperative planning and simulation data sets, including the generation of virtual models with the mirror tool, were used as a virtual template to guide surgical correction of those deformities by intraoperative instrument- and/or probe-based navigation. The outcome was checked by both superimposing the postoperative 3-dimensional computed tomography model on the preoperative planning model and clinical examination.

RESULTS

Through registration, an accurate match between the intraoperative actual position and 3-dimensional virtual model was achieved with a systematic error of 1 mm difference. With the guidance of the navigation system, the average deviation of the morphologic change after surgical correction was less than 1 mm according to the image comparison between the preplanned and postoperative computed tomography. The 1- to 2-year follow-up evaluation showed that the clinical complaint symptoms were alleviated, and the postoperative function and esthetics improved remarkably.

CONCLUSIONS

Navigation-guided correction in the treatment of midfacial post-traumatic deformities can be regarded as an ideal and valuable option for this potentially complicated procedure.

Innovations in osteosynthesis and fracture care

Over the years giant steps have been made in the evolution of fracture fixation and the overall clinical care of patients. Better understanding of the physiological response to injury, bone biology, biomechanics and implants has led to early mobilisation of patients. A significant reduction in complications during the pre-operative and post-operative phases has also been observed, producing better functional results. A number of innovations have contributed to these improved outcomes and this article reports on the advances made in osteosynthesis and fracture care.

Development of a method for ultrasound-guided placement of pedicle screws

Abstract-Many forms of spinal fusion involve the placement of long screws through the pedicles into the vertebral body. During the procedure, there is substantial risk of damage to vital neural and vascular structures due to the limited visibility of anatomic landmarks and high anatomic variability. As an alternative to current guidance systems, we have investigated the feasibility of performing ultrasound imaging through cancellous bone for the purpose of pedicle screw guidance. Quantitative ultrasonic characterization and A-mode imaging of seven defatted vertebral cancellous bone specimens was performed along the craniocaudal axis in water with unfocused, 1-MHz and 3.5- MHz broadband transducers. The center frequency attenuation increased considerably from 10.5 +/- 4.6 dB/cm at 1 MHz to 24.1 +/- 7.2 dB/cm at 3.5 MHz, while the speed of sound exhibited moderate positive dispersion, increasing from 1489 +/- 4.7 m/s at 1 MHz to 1494 +/- 4.2 m/s at 3.5 MHz. Despite the high attenuation and large specimen thickness (1.0-1.9 cm), A-mode imaging through cancellous bone to detect an aluminum reflector was possible in 83.2% and 70.1% of the cases at 1 MHz and 3.5 MHz, respectively. Specimen boundaries were identifiable with clinically sufficient average accuracy of 1.1 mm and 0.9 mm in the 1 MHz and 3.5 MHz A-mode images, respectively.

X-ray-based machine vision system for distal locking of intramedullary nails

In surgical procedures for femoral shaft fracture treatment, current techniques for locking the distal end of intramedullary nails, using two screws, rely heavily on the use of two-dimensional X-ray images to guide three-dimensional bone drilling processes. Therefore, a large number of X-ray images are required, as the surgeon uses his/her skills and experience to locate the distal hole axes on the intramedullary nail. The long-term effects of X-ray radiation and their relation to different types of cancer still remain uncertain. Therefore, there is a need to develop a surgical technique that can limit the use of X-rays during the distal locking procedure. A robotic-assisted orthopaedic surgery system has been developed at Loughborough University to assist orthopaedic surgeons by reducing the irradiation involved in such operations. The system simplifies the current approach as it uses only two near-orthogonal X-ray images to determine the drilling trajectory of the distal locking holes, thereby considerably reducing irradiation to both the surgeon and patient. Furthermore, the system uses robust machine vision features to reduce the surgeon's interaction with the system, thus reducing the overall operating time. Laboratory test results have shown that the proposed system is very robust in the presence of variable noise and contrast in the X-ray images.

Image guided surgery: New technology for surgery of soft tissue and bone sarcomas

AIM

Providing the surgical oncologist with a new means of performing safe and radical sarcoma surgery with the help of image guidance technology.

METHOD

Two patients with pelvic sarcomas were operated upon with the help of an intra-operative navigation system. The technology of image guided surgery is described in one patient with a retroperitoneal sarcoma invading the bony pelvis and another patient with a chondrosarcoma of the iliac crest.

RESULTS

We show that this new procedure enables optimal radical surgical resection with minimal treatment related morbidity or loss of function.

CONCLUSION

Image guided surgery is a new technical tool in sarcoma surgery.

Proposal for Conceptual designing of An Innovative C-arm Calibration Target

In the existing fluoroscopic-image-based orthopedic surgical navigation system, C-arm calibration target has several shortcomings. In order to overcome these shortcomings, an innovative conceptual design for calibration target is proposed. If the redesigned calibration target can be materialized and substituted for the existing one, and relevant software can be adapted accordingly, performance of surgical navigation system is hopefully to be promoted, and development-running cost be decreased.

Real-time Navigation in Orthognathic Surgery

In order to realize real-time navigation in orthognathic surgery, i.e. to realize real-time tracking the pose (position and rotation) of the patient and the instruments, we developed a 3D osteotomy simulation and real-time navigation system (3D OsteoSim&Nav) for the first time in China. After the preoperative 3D simulation, system matches the markers on 3D model to the markers in surgical patient's site to complete the registration. Then the system real-time tracks the pose of the surgical instruments and patient, and real-time offset the site change of the patient. In this way the doctor can accurately operate according to the simulative results. The experimental results show that this navigation system works well and improves the surgical precision.

Early experience with computer-assisted shoulder hemiarthroplasty for fractures of the proximal humerus: development of a novel technique and an in vitro comparison with traditional methods

A computer-assisted technique was developed for treatment of 4-part proximal humeral fractures via a hemiarthroplasty and tuberosity fixation. This was compared with a standard traditional method in 7 pairs of cadaveric shoulders. The computer-assisted technique used preoperative computed tomography data and computer simulations of anatomic characteristics of the contralateral humerus. This allowed accurate anatomic reconstruction by use of an electromagnetic tracking system and real-time intraoperative feedback. Various anatomic measurements were used to quantify the accuracy of the reconstruction. The differences between the intact and reconstructed values were improved with the computer-assisted technique for 5 of 7 characteristics. However, this was statistically significant only for humeral head offset (P < .05). With further investigation and refinement, this technique should allow for a more anatomic reconstruction of the proximal humerus, potentially resulting in improved patient outcomes. The technique may also prove to be a valuable resource for the laboratory training of inexperienced surgical trainees.

Randomized clinical study to compare the accuracy of navigated and non-navigated thoracic pedicle screws in deformity correction surgeries

STUDY DESIGN

Randomized clinical trial (level I evidence).

OBJECTIVE

To compare the accuracy of non-navigation and Iso-C based navigation in pedicle screw fixation in thoracic spine deformities.

SUMMARY OF BACKGROUND DATA

Thoracic pedicle screw insertion for spinal deformity correction can be associated with increased pedicle breaches. Iso-C based navigation has been reported to improve the accuracy of pedicle screw placement, but its use in the presence of deformity has not been reported.

METHODS

Twenty-seven patients with scoliosis and 6 patients with kyphosis had a total of 478 thoracic pedicle screws. The average Cobb angle was 58.4 degrees +/- 8 degrees (range 50 degrees -80 degrees), and the mean kyphotic angle was 54.6 degrees +/- 4 degrees (range 51 degrees -76 degrees). By random allocation, 17 patients had screw insertion under navigation (242 screws) and 16 under fluoroscopic control (236 screws). The 2 groups were compared for accuracy of screw placement, time for screw insertion, and the number of times the C-arm had to be brought into the field. Two independent blinded observers determined accuracy using postoperative computed tomography assessments.

RESULTS

There were 54 (23%) pedicle breaches in the non-navigation group as compared to only 5 (2%) in the navigation group (P < 0.001). Thirty-eight screws (16%) in the non-navigation group had penetrated the anterior or lateral cortex compared to 2 screws (0.8%) in the navigation group. Average screw insertion time in the non-navigation group was 4.61 +/- 1.05 minutes (range 1.8-6.5) compared to 2.37 +/- 0.72 minutes (range 1.16-4.5) in navigation group (P < 0.01). The C-arm had to be moved into the operation field on an average of 1.5 +/- 0.25 times (range 1-3) per screw. With single screening data, an average of 11.4 pedicles (range 9-14) could be visualized without necessity to bring the C-arm into operating field again.

CONCLUSIONS

Iso-C navigation increases accuracy, and reduces surgical time and radiation in thoracic deformity correction surgeries.

A system for ultrasound-guided computer-assisted orthopaedic surgery

Current computer-assisted orthopedic surgery (CAOS) systems typically use preoperative computed tomography (CT) and intraoperative fluoroscopy as their imaging modalities. Because these imaging tools use X-rays, both patients and surgeons are exposed to ionizing radiation that may cause long-term health damage. To register the patient with the preoperative surgical plan, these techniques require tracking of the targeted anatomy by invasively mounting a tracking device on the patient, which results in extra pain and may prolong recovery time. The mounting procedure also leads to a major difficulty of using these approaches to track small bones or mobile fractures. Furthermore, it is practically impossible to mount a heavy tracking device on a small bone, which thus restricts the use of CAOS techniques. This article presents a novel CAOS method that employs 2D ultrasound (US) as the imaging modality. Medical US is non-ionizing and real-time, and our proposed method does not require any invasive mounting procedures. Experiments have shown that the proposed registration technique has sub-millimetric accuracy in localizing the best match between the intraoperative and preoperative images, demonstrating great potential for orthopedic applications. This method has some significant advantages over previously reported US-guided CAOS techniques: it requires no segmentation and employs only a few US images to accurately and robustly localize the patient. Preliminary laboratory results on both a radius-bone phantom and human subjects are presented.

Orthopedic personnel roles in the OR for computer assisted total knee arthroplasty

The methods and problems associated with traditional total knee arthroplasty surgery and the development and advantages of computer-assisted surgery (CAS) are discussed in this article. In the next decade, CAS products have the potential to transform as many as 25% of all orthopedic surgical procedures from techniques that largely depend on line of sight and traditional instruments to techniques that use integrated surgical instruments and computer technology. This technology could revolutionize orthopedic surgery, the lives of patients, and the work of perioperative staff members during the next decade.

The historical importance of the hand in advancing the study of human anatomy

Anatomy is often considered the foundation of medical science and is basic to the education of health professionals. This report will attempt to summarize the history of anatomy from antiquity to modern times. In addition it will highlight the historical importance of the upper extremity and its relationship to the development of human anatomy as a recognized medical science.

Neglected femoral diaphyseal fracture

Femoral diaphyseal fractures usually result after trauma of high magnitude and because of this, can be life-threatening injuries or may result in considerable physical disability if not treated with care and caution. Nonoperative treatment of these fractures continues to be popular among the patient population in the Indian subcontinent, which in majority of cases, leads to healing in malalignment, shortening of the limb, chondromalacia patellae, and loss of knee motion. Although the majority of these fractures are being treated by operative methods today, success of the treatment depends largely on the surgeon's familiarity with the procedure or the type of fracture pattern (comminuted or segmental) particularly in a polytraumatized patient. Delayed union and nonunion of femoral-diaphyseal fractures and implant failures usually result after these procedures or the type of injury. The purpose of this study is to discuss various types of neglected femoral diaphyseal fractures and to review the literature on their treatment.