Background:

Potential injury to the common peroneal nerve at the level of the fibula head/neck junction during fine wire insertion in stabilization of proximal fibula, is a recognised complication. This study aims to relate the course of the common peroneal nerve to fibula head transfixion wire.

Background:

Septic arthritis following intra-capsular penetration of the knee by external fixation devices is a complication of traction/fixation devices. This study aimed to demonstrate the capsular attachments and reflections of the distal femur to determine safe placements of wires.

Introduction: To assess the effectiveness of a regional basic external fixation trauma course.

Methods: Effectiveness of an annual, low-cost, Royal College of Surgeons of England approved, regional basic ex-fix course, led by consultant trauma experts from Yorkshire, UK, covering anatomy, surgical techniques, biomechanics, early management of open fractures and temporary external fixation placement was assessed. Pre- and post-course questionnaires asking grade, current hospital, previous experience, and a mini-test to design a temporary ex-fix construct for four fracture patterns (IIIb open tibia, open book pelvis, Schatzker 6, and total articular pilon) were used. Designs were assessed for stability, safe corridors and plastics assess.

Results:

- 10/22 participants had not previously attended an ex-fix course.

Discussion: Recently Pearse and Naique reported a 48% fixation revision rate in open tibial fractures transferred for tertiary care, suggesting that improved core skills are required to ensure appropriate packaging of patients prior to transfer with open, complex articular and pelvic fractures.

Participation in a simple ex-fix course improves knowledge of ex-fix design. Retention of knowledge must be reassessed after several months.

This course fills a gap in education of basic external fixation for orthopaedic trainees. We recommend every region with a tertiary referral system for complex trauma utilises this course.

Aim: To develop a 3-D pre-surgical planner that facilitates selection and placement of correct prosthetic components in the joint, and the design of patient specific templates to use intra-operatively to reproduce the pre-planned implantation procedure, in total knee replacement (TKR) surgery.

Design/Methods: The process begun with loading of pre-operative CT scan data of cadaver knee, onto medical software, followed by reconstructions of 3D models of the joint. Then measurements of anterior-posterior diameter of the femoral condyles of the 3D models of the joint were used to select and import a correct CAD drawing of prostheses from a database of electronic files available in a range of sizes. The selected prosthetic components were positioned and aligned on the 3-d model of the joint, making sure that the anterior flange of the femoral prosthesis component did not violate superior cortical bone of trochlea. Whilst the tibial stem was placed central within the medullar space of the bone, and the plane of the tibial cut was perpendicular to the long axis of the tibia. The planned data were next exported to a CAD environment where template to prepare the bone to receive the prostheses, was designed. A template was designed to press fit on a bone (e.g. femur), via minimum number of cylindrical protrusions with their ends made to conform to the geometry of that bone at the regions of contact. The integrated surgical tools were secured to the bones with pins through each of the protrusions, and were equipped with saw guide slits for cutting the bone, and with drill guides for drilling the fixation holes. Thereafter the files describing templates and prosthetic components selected for cadaveric joint concerned were sent to rapid prototyping machine for manufacturing.

Results: Fourteen procedures were performed on cadaveric knees to date. Visual examination of the joint has revealed the 3-D planning system enabled correct selection of appropriate prosthetic components and alignment, as evidenced by absence of protrusions or overhanging beyond the edges of the bones. The resected bone surfaces were visually smooth and flat. Gaps between the bones and the internal surfaces of the prosthetic components were measured using steel shim gauges, and largest recorded was 0.9mm. Laxity between the femur and tibia was absent and the joint attained full range of flexion. Dimensional deviations of post-operative scans of the prepared bones from the pre-planned ones were between 0.5 and 0.9mm. The templates after their use were shown capable to withstand the rigors of theatre environment.

Conclusion: With the planning software, it has been shown that it is possible to design a simple to use implantation guidance system according to the final position of the restorative prosthesis and the bone pathological condition. Pre-operative planner system relieves the clinician from multiple intra-operative decisions. The system is ideal for critical anatomical situations and eliminates possible manual placement errors such as those from extra and intra-medullary alignment tool. Less inventory required of both implants and instrumentation means reduced complexity of procedure, surgical time and cost.

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.

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 ßuoroscopic 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 ßuoroscopic images of all the patients showed accurate position of the guide wire both in AP and lateral planes. Only 4 ßuoroscopic 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.

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.

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.

Methods: CAOSS helps in surgical planning and aid surgeons for accurate guide wire placement into femoral neck. After fracture reduction, intra-operative computer based surgical planning was performed using one fluoroscopic 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. Intra-operative fluoroscopic images of all the patients showed accurate position of the guide wire both in AP and lateral planes. In theory only 4 fluoroscopic images are required during this surgical procedure in total. But in practice, more than 4 were required depending upon the experience of the radiographer. None of the patient had any intra-operative complication. Conclusions: The computer aided surgery was found to be safe, accurate and reliable for guide wire placement for dynamic hip screw insertion.