Introduction: Surgical training is being greatly affected by the challenges of reduced training opportunities, shortened working hours, and financial pressures. There is thus an increased need for training systems to aid development of psychomotor skills of the surgical trainee. Furthermore, simulation environments can provide a friendlier and less hazardous environment for learning surgical skills. Such simulations may be used to augment training in the operating room (OR) so that trainees acquire key skills in a non-threatening and unhurried environment. Trajectory planning and implementation forms a substantial part of current and future orthopaedic practice. This type of surgery is governed by a basic orthopaedic principle where the placement of a surgical tool at a specific site within a region via a trajectory that is planned from X-ray based 2D images and is governed by 3D anatomical constraints. The accuracy and safety of procedures utilising the basic orthopaedic principle depends on the surgeon’s judgement, experience, ability to integrate images, utilisation of intra-operative X-ray, knowledge of anatomical-biomechanical constraints and eye hand dexterity. With the decrease in training opportunities in OR for the surgical trainee, these skills are developing at a much later stage in training. Several studies have shown a reduction in the number of operations undertaken and a reduction in the level of competence achieved by surgical trainees. Purpose of the study: This study develops our existing surgical CAOSS (Computer Assisted Orthopaedic Surgical System) [4, 5] for fracture fixation into a training tool for skill acquisition of the basic orthopaedic principle, namely, 3D navigation using 2D X-ray images. Material and Methods: Orthopaedic trainees who are presently working in Hull and East Yorkshire NHS Trust are recruited in this study. The study is divided into two parts. The initial part of the study involves the use of the conventional CAOSS to train the orthopaedic trainees with no prior exposure of distal locking of femoral nails and the dynamic hip screw. The second part of the study involves the use of modified CAOSS to assess whether the initial training has helped in developing mental navigation skills of using a 2-D image and navigating the drill bit in 3-D space. The scoring system is based on a combination of parameters which include the time taken for centring of the interlocking screw, total exposures taken and the improvement in the position of the tip of the drill bit with each exposure. Results: The presentation will discuss the theories, methodology and scoring criteria to produce a training tool for training of the basic orthopaedic principle and how the training tool was validated. Discussion: The ability to quantify precisely three-dimensional navigation and processing of virtual information to help in hand eye co-ordination has not previously been used as a formal orthopaedic training tool. Clearly the assessment of such skills demands a scoring system that is both reproducible as well as being able to validate it that it predicts skill acquisition correctly. Currently, there is no known scoring system which can accurately assess the ability to navigate instruments in 3-D space using a C-arm image. We therefore propose that using CAOSS as a training tool for the surgical trainees in a relaxing less hurried environment is beneficial to training and we also propose for this tool a reproducible scoring system.

The Phantom based Computer assisted orthopaedic surgical system (CAOSS) has been developed collaboratively by the University of Hull and the Hull Royal Infirmary, to assist in operations like dynamic hip screw fixation. Here we present summary of our system. CAOSS comprises a personal computer based computer system, a frame grabber with video feed from a C-arm image intensifier, an optical tracking system and a radiolucent registration phantom which consists of an H arrangement of 21 metal balls. The phantom is held in position by the optically tracked end-effector. Knowing the optical position of the phantom, a registration algorithm calculates the position of C-arm in coordinate space of the optical tracking system. Computer based planning uses an anteroposterior (AP) and lateral image of the fracture. Marks are placed on the 2D projections of femoral shaft, neck and head on the computer screen, which are then used to create 3D surgical plan. The computer then plans a trajectory for the guide wire of DHS. The depth of the drill hole is also calculated. The trajectory is then shown on both AP and lateral images on the screen. CAOSS meets all the requisite of electrical and electromagnetic radiation standards for medical equipment. There has been extensive validation using software simulation, performance evaluation of system components, extensive laboratory trials on plastic bones. The positional accuracy was shown to be within 0.7mm and angular accuracy to be within 0.2°. The system was also validated using Coordinate Measurement Machine. Our system has the unique feature of the registration phantom which provides accurate registration of the fluoroscopic image.

Though the perceived advantages of computer assisted orthopaedic systems (CAOS) have been claimed incessantly over the years, these systems are far from commonplace in most orthopaedic theatres. Here, we present a summary of those very reasons. Health Technology Assessment report elicited no proof of clinical benefits of the Robodoc over conventional procedures. Mazoochian et al were unable to confirm the same accuracy of implant position while using the Caspar. Honl et al found a higher revision and dislocation rate accompanied with longer surgery durations when robotic assisted technology was used. Shortcomings identified in the CT-based navigation systems included an additional CT scan, which represents extra costs for the acquisition as well as additional radiation to the patient. Sistan et al claims that image-free navigational systems in knee arthroplasty do not provide a more reliable means for rotational alignment as compared to traditional techniques. Computer assisted pedicle screw insertion in the spine has also not demonstrated any significant clinical advantages. To date, long term results of computer-guided or robot-assisted implantation of endoprosthetic devices are still lacking. With the unproven long-term clinical and functional results of patients who had computer aided surgery and given the multi-factorial complexities of patient outcome, it is difficult to claim via small scale short term studies that these systems present a significant benefit to the patient or the healthcare providers. Potential benefits of long-term outcome, better implant survival and functional improvement require further investigation and until that information is available this technology must be further developed before its widespread usage can be justified.

The use of the C-arm fluoroscope for surgical navigation in various Computer Assisted Orthopaedic Surgery Systems (CAOS) has been an important success of research into CAOS technology. To use the fluoroscope for quantitative surgical navigation involves calibrating its 2D images and tracking the spatial position of the fluoroscope's image beam. This allows 3D reconstruction of anatomy from a series of 2D fluoroscopic images. This paper presents a new technique for determining the C-arm position and calibrating the image beam. This technique is based on a small imaging phantom that is placed close to the patient. This paper also briefly describes the CAOS system developed at Hull that uses this imaging phantom and reports on in vivo and in vitro studies.

The difficult part of the intramedullary (IM) nailing operation of long bone is to insert the distal locking screws. The current technique to insert these screws uses numerous fluoroscopic images and depends on skills and expertise of the surgeon. A Computer-Assisted Orthopaedic Surgical System (CAOSS) has been developed collaboratively by the University of Hull and the East Yorkshire Hospitals NHS Trust to assist the orthopaedic surgeons in these operations. The laboratory based test results for insertion of distal locking screws in intramedullary nailing procedure are presented and discussed in terms of accuracy and as part of the validation process to introduce new CAOS procedures into clinical use. This study shows that CAOSS in IM nails is robust and reliable. The positional accuracy in planning the trajectory for insertion of the distal locking screws was shown to be within 0.3 mm and angular accuracy within 0.2°.

Aims: Dynamic hip screw (DHS) is a common implant used for extracapsular fracture neck of femur. Accurate placement of the guide wires for the DHS insertion is the most important surgical step. In order to improve precision and accuracy of the guide wire placement, Computer Assisted Orthopaedic Surgery System (CAOSS) was used which was developed at the University of Hull. Early clinical experience in 14 cases is presented. Methods: CAOSS helps in surgical planning and aid surgeons for accurate guide wire placement into femoral neck. After fracture reduction, intraoperative computer based surgical planning was performed using one suoroscopic image in two planes each. A trajectory obtained thus helped surgeon to place a guide wire along with the required course under the computer guidance. Results: CAOSS system was used on 11 patients for guide wire placement. Intraoperative suoroscopic images of all the patients showed accurate position of the guide wire both in AP and lateral planes. Only 4 suoroscopic images were required during the surgical procedure in total, both pre and post guide wire insertion. Conclusions: The computer aided surgery used in guide wire placement for dynamic hip screw insertion proves to be accurate and reliable. It also reduces ionisation radiation exposure to the surgeon, patients and theatre personnel.

Aims: Dynamic hip screw for intertrochanteric fractures is one of the most common procedures performed by orthopaedic surgeons. The prerequisite for proper placement of the implant is accurate insertion of the guide wire. The Computer Assisted Orthopaedic Surgical System [CAOSS] is designed to assist the surgeon by planning the trajectory based on one intra-operative AP and Lateral image from a C-Arm. Methodology: After closed reduction on the fracture table, two near orthogonal x-ray images containing the proximal femur with the registration phantom are obtained using a standard C-Arm and then processed after distortion correction. The phantom is supported by an end effector, which is continuously tracked in 3D space. Features of interest are extracted and the image registered in space through the evaluation of the phantom’s projection in the x-ray image. The versatility of the CAOSS is increased by the provision allowing the adjustment of the planned trajectory to the surgeon’s satisfaction. Once the trajectory is accepted, the surgeon implements the plan by moving a passive manipulator arm, while receiving visual positional cues from the computer in the form of a targeting screen. When the targeting is complete; the arm is locked in position and the trajectory implemented. Results: We present the results of the pilot clinical study involving 10 patients using this device. The results obtained were compared with an equal number of patients randomly selected from the complete neck of femur database, who had undergone a conventional DHS placement, during the last one-year. Accuracy of placement of the implant was assessed by an independent observer and by a previously validated computer program that assesses the accuracy from scanned post operative X-rays. The average targeting time was 6 minutes and overall there was no significant difference between the two groups.

Hull Medical Engineering (HULMEC) group was established in 1992 as a collaboration of orthopaedic surgeons and various research groups from the University of Hull to promote multidisciplinary research especially the application of computers to aid in surgery. With the joint effort of researchers and surgeons CAOSS was developed. The key aim of the CAOSS has been to use intra-operative surgical planning using fluoroscopic based images, hence this system aids in performing those procedure which requires fluoroscopy namely dynamic hip screw guide wire insertion, distal locking of the screw and placement of cannulated hip screw. The major steps of CAOSS are the precision calibration of the fluoroscopic images, use of these images for accurate intra operative surgical planning, innovative planning algorithms, and a safe, rapid and accurate approach to trajectory execution. CAOSS has been used on the plastic bones in the laboratory setting and was found to be accurate. Presently CAOSS has been used in an ethically approved clinical trial for guide wire insertion for the DHS placement. Perceived Advantages of CAOSS Safe Passive system Non-invasive Surgeon maintains decision making Decreasing radiation exposure Reducing complexity of the procedure Reducing technical failures Reducing operating time Improving accuracy of implant placement Reducing bone damage (by reducing repeated guide wire insertion) Improving Patient outcome Cost Effective Easy to use

A total of 125 consecutive hip fracture patients were investigated regarding hip geometry. There were 33 men of mean age 76 ± 10 years, and 92 women of mean age 78 ± 9 years. Patients with previous hip surgery were excluded. Hip geometry (hip-axis length, width of collum femoris, and femoral shaft and neck-shaft angle) were registered on both plain radiographs and DEXA scans performed within 2 weeks after fracture. On the radiographs, the calcar femorale, the Singh index, and the femoral neck index (FNI) were also calculated and compared with earlier published values of bone mineral density hip in the hip fracture patients. The fracture cases were compared with controls, 192 DEXA scans and 163 radiographs, in patients without hip surgery or known hip disease. As measured on the DEXA scans we found a wider collum femoris and a wider femoral shaft in both the male and female fracture cases, compared to controls. Also, the fracture cases showed signs of osteoporosis as measured by the calcar femorale, the Singh index, and the femoral neck index. These measurements showed good correlation with bone mineral density of the hip as measured by the DEXA scans.

Healthcare organisations are accountable for improving the quality of their services, safeguarding high standards of care and meeting shorter waiting time targets. This presents a challenge of how to achieve such targets with limited resources. This paper looks at the hypothesis that adequate and appropriate clinical governance can be undertaken while increasing orthopaedic spinal clinic throughput in order to decrease outpatient waiting times. A spinal outpatient clinic was used as the test bed for the hypothesis of the project. The theoretical number of patients an individual consultant can see per session was calculated from recommended British Orthopaedic Association consultation times for new and follow-up cases. Patients were asked to complete the MODEMS (Musculoskeletal Outcomes Data Evaluation and Management System) questionnaire. A prospective randomised trial utilising a touch-screen computerised version of the questionnaire was also used. Time taken for outcome data management is included in the analysis. The time taken to see new and follow up patients was 31–42 and 24–35 minutes respectively. These times have implications in terms of waiting times and Director of Performance Management targets. The shortfall is calculated in terms of additional support necessary to reach these targets. Salary costs and infrastructural support costs are projected. The figure is likely to represent that required by any specialist clinic to realise the ideals of clinical governance and conservatively estimated to be £35, 000 per year. Total clinical governance and patient outcomes are inextricably linked. This is true of orthopaedic spinal surgery in that important information about clinical practice can be obtained. The organizational infrastructure and methods to implement data collection is technically feasible however is not without cost. In terms of economic evaluation the correct price for a resource is its opportunity cost. ‘Don’t just buy more healthcare, invent new healthcare’ is as incongruous as total clinical governance and increased capacity without support.

In intramedullary nail (IMN) surgical operations, one of the main efforts for surgeons is to find the axes of two distal holes. Two distal holes on an IMN, which are inside the intramedullary canal of a patient's femur, can only be seen in a lateral X-ray view. For the standard surgical procedure, the localization of the distal hole axes is a trial-and-error process which results in a long surgical time and large dose of X-ray exposure. In this paper, an algorithm to derive the three-dimensional position and orientation of the distal hole axis was developed. The algorithm first derives the nail axis through two X-ray images. Then the distal hole axis is calculated through projecting back the hole boundary on the X-ray image from a lateral view to three-dimensional space. A least-squares method is used to determine the centres of the front hole and the back hole through iteration. The algorithm has been tested with real data and it was robust.

Finite element analysis is a widely accepted tool used in many industries and research activities. It allows new designs to be thoroughly ‘tested’ before a prototype is even manufactured, components and systems which cannot readily be experimented upon to be examined, and ‘diagnostic’ investigations to be undertaken. Finite element models are already making an important contribution to our understanding of the spine and its components. Models are being used to reveal the biomechanical function of the spine and its behaviour when healthy, diseased or damaged. They are also providing support in the design and application of spinal instrumentation. The spine is a very complex structure, and many of the models are simplified and idealized because of the complexity and uncertainty in the geometry, material properties and boundary conditions of these problems. This type of modelling simplification is not peculiar to spinal modelling problems. Indeed, the idealization is often a strength when there is such uncertainty and variation between one individual and another, allowing cause-effect relationships to be isolated and fully explored, and the inherent variability of experimental tests to be eliminated. This paper reviews the development of finite element analysis in spinal modelling. It shows how modelling provides a wealth of information on our physiological performance, reduces our dependence on animal and cadaveric experiments and is an invaluable complement to clinical studies. It also leads to the conclusion that, as computing power and software capabilities increase, it is quite conceivable that in the future it will be possible to generate patient-specific models that could be used for patient assessment and even pre- and inter-operative planning.

Objective: A patient-specific finite element model of the spine is being developed to aid the surgeon in the diagnosis and clinical management of spinal conditions 1 . To validate the application of the computer model, a laboratory validation spine is being developed. This study is concerned with the development and basic characteristics of the intervertebral disc component of the laboratory spine. Method: The external profile of the laboratory disc was determined from CT images of a cadaveric spine. A two-part silicon rubber was used to form the annulus part of the disc. Prior to sealing it was possible to fill the cavity with an appropriate medium (such as grease or oil) to represent the nucleus pulposus with the further option of applying external pressurisation through a small pressure inlet in the wall of the disc. The laboratory disc was then tested in denucleated form, and grease-filled with initial intradiscal pressures of 0, 0.1, 0.2 and 0.3 MPa. A finite element model of the disc was also developed and used to investigate the characteristics of the laboratory disc. Results: The agreement between the finite element results and experimental test results was excellent and the compressive and flexural load-deflection characteristics of both intact and denucleated laboratory discs were found to lie within the range of values reported in the literature for cadaveric discs. Disc bulge characteristics of the intact and denucleated silicon discs were also similar to that observed with natural discs in vitro. Conclusions: An artificial disc for a laboratory validation spine has been developed and shown to have representative characteristic properties in compression loading. The disc is now being modelled and tested in torsion.

This paper describes the mathematics of acquiring a cone axis through the projection of its conical boundary from X-ray images. A thorough analysis and rigorous proofs are presented for a better understanding of this basic problem. The results can be directly used for the trajectory planning of sliding hip screw and IntraMetullary nail operations by the computer assisted orthopaedics surgical systems.