Aim: The Computer Assisted Orthopaedic Surgical System [CAOSS] is designed to assist the surgeon in performing the task of accurate placement of the distal locking screws via a trajectory that is planned by one AP and Lateral image from the conventional C-Arm. Methodology: Two near orthogonal x-ray images containing the distal femur with the registration phantom and including the distal end of the nail with the two locking holes 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 by an overhead camera. Features of interest are extracted and the image registered in 3D space through the evaluation of the phantomñs projection. A computer-based model of the anatomical region is developed and the position of the screws planned. Even if the distal locking hole image is not a true circle, the software is robust enough to detect the difference in curvature of the upper and lower part of the ellipse and thus calculate the necessary angle at the time of insertion. 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. Two individuals used the device for distal locking of Richards intra medullary femoral nail in several saw bone models. Results and Conclusions: Successful locking was accomplished in all cases by using the trajectory planned using one AP and Lateral image. This was the case even when the image was not a true lateral of the locking hole. The results of this study using this new versatile system, including the number of x-rays required, duration of x-ray exposure and time for distal targeting and locking are presented.

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.

Introduction: Virtual Reality arthroscopic training systems offer the potential for improved training, assessment and evaluation of surgical skills. Of the various virtual reality arthroscopic training systems available, the main limiting factors preventing their use as a standard training tool is the lack of force feedback. No force data is available from in vivo measurements, which would serve as the basis for the development of such a system. Methodology: We attached a six axis force torque (FT) sensor to a standard arthroscopic probe while at the same time making necessary modiþcations to meet the safety and sterility requirements, and measured in vivo the forces and torques generated during various standard tasks of a routine knee arthroscopy. [The procedure was split into 11 separate tasks] A simultaneous video recording of the procedure was made and synchronized to the force torque recording by using an audio signal. A pilot study to evaluate the difference between experienced and less experienced arthroscopists was also undertaken. Results and conclusions: For comparison and evaluation purposes the vectored XY torque recording was used. Comparison between junior and senior arthroscopic surgeons was done by assessing the XY Torque distribution over time and evaluation of the graph patterns generated while performing similar tasks. Though differences can be seen, it did not show any statistical signiþcance. Successful completion of an arthroscopic procedure requires adequate visualization and gentle manipulation of instruments and tissues within the knee. The use of a force torque sensor in arthroscopic training systems will allow detection of and warn when excessive potentially damaging forces are being used. This will provide a means for improving training as well as a method of evaluation, including revalidation.