Computer Aided Surgery : Official Journal of the International Society for Computer Aided Surgery

Primary and metastatic liver tumors constitute a significant challenge for contemporary medicine. Several improvements are currently being developed and implemented to advance image navigation systems for percutaneous liver focal lesion ablation in clinical applications at the diagnosis, planning and intervention stages. First, the automatic generation of an anatomically accurate parametric model of the preoperative patient liver was proposed in addition to a method to visually evaluate and make manual corrections...

PURPOSE: To introduce easy and useful methods using 3D navigation system with skin-fixed dynamic reference frame (DRF) in anterior cervical surgery and to validate its accuracy. METHODS: From September 2012 to May 2013, 31 patients underwent anterior cervical surgery and a total of 48 caspar distraction pins were inserted into each cervical vertebra. Every operation was performed using O-arm® navigation system with skin-fixed DRF. To validate the accuracy of these methods, a custom-made metal sleeve was used...

This study describes computer simulation of blood flow and plaque progression pattern in a patient who underwent surgical treatment for infected carotid prosthetic tube graft using carotid-carotid cross-over bypass. The 3D blood flow is governed by the Navier-Stokes equations, together with the continuity equation. Mass transfer within the blood lumen and through the arterial wall is coupled with the blood flow and is modelled by the convection-diffusion equation. Low-density lipoprotein (LDL) transport in lumen of the vessel is described by Kedem-Katchalsky equations...

This study evaluated the influence of intra-operative soft tissue balance on post-operative range of motion in patients undergoing posterior-stabilized total knee arthroplasty with navigation. After implantation of all components in 31 consecutive patients, the joint component gap was measured manually with the knee at 0°, 90°, and 120° as guided by a navigation system. We designated soft tissue balance as the absolute difference between varus stress and valgus stress (medio-lateral laxity). Changes in medio-lateral laxity were calculated from 120° to 90°, 120° to 0°, and 90° to 0°...

OBJECT: The individualized Starfix® miniframe belongs to a new generation of stereotactic systems enabling high-precision electrode placement with considerably better time-efficiency in deep brain stimulation (DBS). We evaluated the usability and reliability of this novel technique in patients with idiopathic Parkinson's disease (IPD) and compared surgical and clinical results with those obtained in a historical group in which a conventional stereotactic frame was employed. METHODS: Sixty patients underwent surgery for implantation of DBS electrodes in the subthalamic nucleus...

BACKGROUND: Recently, two topical issues in total hip arthroplasty (THA) have been robot-assisted surgery and use of a short stem. The purpose of this study was to evaluate the effects of robotic milling on the accuracy of short femoral stem positioning and on the short-term clinical outcome in THA using a prospective, randomized design. METHODS: We randomized 54 patients into two groups, either robotic milling group or manual rasping group. The patients were assessed clinically and radiographically at 8 weeks, 5 months, 12 months, and 24 months...

Optimal component alignment in total knee arthroplasty has been associated with better functional outcome as well as improved implant longevity. The ability to align components optimally during minimally invasive (MIS) total knee replacement (TKR) has been a cause of concern. Computer navigation is a useful aid in achieving the desired alignment although it is limited by the error during the manual registration of landmarks. Our study aims to compare the registration process error between a standard and a MIS surgical approach...

Resection of a pelvic tumor is challenging because of its complex three-dimensional (3D) anatomy and deep-seated location with nearby vital structures. The resection is technically demanding if a custom implant is used for reconstruction of the bone defect as the surgeon needs to ensure the resection margin is sufficiently wide and the orientation of intended resection planes must match that of the custom implant. We describe a novel workflow of performing a partial acetabular resection in a patient with pelvic chondrosarcoma and reconstruction with a custom pelvic implant in a one-step operation...

OBJECTIVE: In total hip arthroplasty, it is important to assess postoperative implant orientation. The computed tomography-based (CT-based) three-dimensional (3D) templating method using 3D preoperative planning software is generally recommended. In this method, postoperative implant orientation within a bony coordinate system can be measured by overlaying a 3D computerized model of the implant on a real postoperative CT image of the implant. The bony coordinate system consists of several reference points (RPs) marked on a CT image of the bone surface...

OBJECTIVE: We developed a novel method of producing accurate range images of the velopharynx using a three-dimensional (3D) endoscope to obtain detailed measurements of velopharyngeal movements. The purpose of the present study was to determine the relationship between the distance from the endoscope to an object, elucidate the measurement accuracy along the temporal axes, and determine the degree of blurring when using a jig to fix the endoscope. METHODS: An endoscopic measuring system was developed in which a pattern projection system was incorporated into a commercially available 3D endoscope...

OBJECTIVE: Non-invasive navigation techniques have recently been developed to determine mechanical femorotibial alignment (MFTA) in extension. The primary aim of this study was to evaluate the precision and accuracy of an image-free navigation system with new software designed to provide multiple kinematic measurements of the knee. The secondary aim was to test two types of strap material used to attach optical trackers to the lower limb. METHODS: Seventy-two registrations were carried out on 6 intact embalmed cadaveric specimens (mean age: 77...

Computer models capable of predicting elbow flexion and extension range of motion (ROM) limits would be useful for assisting surgeons in improving the outcomes of surgical treatment of patients with elbow contractures. A simple and robust computer-based model was developed that predicts elbow joint ROM using bone geometries calculated from computed tomography image data. The model assumes a hinge-like flexion-extension axis, and that elbow passive ROM limits can be based on terminal bony impingement. The model was validated against experimental results with a cadaveric specimen, and was able to predict the flexion and extension limits of the intact joint to 0° and 3°, respectively...

Optical coherence tomography (OCT) has been shown to be of clinical value in imaging basal cell carcinoma (BCC). A novel dual OCT-video imaging system, providing automated registration of OCT and dermoscopy, has been developed to assess the potential of OCT in measuring the degree of sub-clinical spread of BCC. Seventeen patients selected for Mohs micrographic surgery (MMS) for BCC were recruited to the study. The extent of BCC infiltration beyond a segment of the clinically assessed pre-surgical border was evaluated using OCT...

BACKGROUND: Within the domain of craniomaxillofacial surgery, orthognathic surgery is a special field dedicated to the correction of dentofacial anomalies resulting from skeletal malocclusion. Generally, in such cases, an interdisciplinary orthodontic and surgical treatment approach is required. After initial orthodontic alignment of the dental arches, skeletal discrepancies of the jaws can be corrected by distinct surgical strategies and procedures in order to achieve correct occlusal relations, as well as facial balance and harmony within individualized treatment concepts...

Non-invasive surface registration methods have been developed to register and track breathing motions in a patient's abdomen and thorax. We evaluated several different registration methods, including marker tracking using a stereo camera, chessboard image projection, and abdominal point clouds. Our point cloud approach was based on a time-of-flight (ToF) sensor that tracked the abdominal surface. We tested different respiratory phases using additional markers as landmarks for the extension of the non-rigid Iterative Closest Point (ICP) algorithm to improve the matching of irregular meshes...

The aim of this study was to assess the rate of collateral soft tissue release required in navigated total knee arthroplasty (TKA) to achieve an intra-operative coronal femoral tibial mechanical axis (FTMA) in extension of 0 ± 2°. The primary outcomes assessed were post-operative coronal plane alignment and rate of collateral soft tissue release. The secondary outcomes were range of motion, function, patient satisfaction, and complication rates at one-year follow-up. This is a prospective study of 224 knees...

Arthrodesis of the first metatarsophalangeal (MTP-1) joint is a widely used procedure for the treatment of hallux valgus in patients with MTP-1 degeneration, severe or recurrent deformity, or inflammatory arthritis. In this case, ten years earlier, the patient's MTP-1 joint had been fused in a severe pronation deformity position. Subsequently, a laterally shifted tibial sesamoid and osseous rising of the phalanx base caused painful callosities. To correct the pronated deformity accurately, a custom-made surgical guide based on a three-dimensional computer tomography (3D-CT) simulation system was used...

OBJECTIVE: This study presents and evaluates a semi-automated algorithm for quantifying malalignment in complex femoral shaft fractures from a single intraoperative cone-beam CT (CBCT) image of the fractured limb. METHODS: CBCT images were acquired of complex comminuted diaphyseal fractures created in 9 cadaveric femora (27 cases). Scans were segmented using intensity-based thresholding, yielding image stacks of the proximal, distal and comminuted bone. Semi-deformable and rigid affine registrations to an intact femur atlas (synthetic or cadaveric-based) were performed to transform the distal fragment to its neutral alignment...

OBJECTIVE: To compare the accuracy of postoperative mechanical alignment in computer-assisted total knee arthroplasties (CAS-TKA) related to various degrees of extra-articular tibial deformity. METHODS: We performed CAS-TKA on 30 knee models in which extra-articular proximal tibial deformities were preset to have malalignments ranging from 30° of varus to 30° of valgus. The knees were assigned to two groups, designated Group A (knees with ≤ 15° preoperative malalignment) and Group B (knees with > 15° preoperative malalignment), and the postoperative mechanical alignment in the two groups was compared using a computer-assisted surgery (CAS) system...

This paper presents an enhanced haptic-enabled master-slave teleoperation system which can be used to provide force feedback to surgeons in minimally invasive surgery (MIS). One of the research goals was to develop a combined-control architecture framework that included both direct force reflection (DFR) and position-error-based (PEB) control strategies. To achieve this goal, it was essential to measure accurately the direct contact forces between deformable bodies and a robotic tool tip. To measure the forces at a surgical tool tip and enhance the performance of the teleoperation system, an optical force sensor was designed, prototyped, and added to a robot manipulator...