Calibration of In-Plane Center Alignment Errors in the Installation of a Circular Slide with Machine-Vision Sensor and a Reflective Marker.

This paper describes a method for calibrating in-plane center alignment error (IPCA) that occurs when installing the circular motion slide (CMS). In this study, by combini ng the moving carriage of the CMS and the planar PKM (parallel kinematic mechanism) with the machine tool, the small workspace of the PKM is expanded, and the workpiece is placed on the table with the CMS installed is processed through the machine tool. However, to rigidly mount the CMS on the table, the preload between the guide and the support bearings must be adjusted with the eccentric bearing, and in this process, the IPCA occurs. After installing a reflective marker on the PKM, the PKM is slowly rotated along with the ring guide in the way of stop-and-go without the PKM's own motion. Then, using a machine vision camera installed at the top of the CMS, the IPCA, which is the difference between the actual center position and the nominal center position of the CMS with respect to the camera, can be successfully calibrated through the circular fitting process. Consequently, it was confirmed that the IPCA of 0.37 mm can be successfully identified with the proposed method.

The medial proximal tibial angle accurately corrects the limb alignment in open-wedge high tibial osteotomy.

PURPOSE: The purpose of this study was to detect the pre- and intra-operative influential factors for lower limb alignment correction error in open-wedge high tibial osteotomy (OWHTO). METHODS: This study involved 69 patients (71 knees) undergoing OWHTO for primary medial osteoarthritis. The weight-bearing line (WBL) ratio, medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA) were measured on radiographs preoperatively and at 1 month after surgery, and the differences between the pre- and postoperative values were calculated. The correction angle during surgery was also investigated. The radiological correction angle was defined as the difference between the pre- and postoperative MPTA. The correction error was defined as the difference between the correction angle during surgery and the radiological correction angle. The ideal correction angle was defined as when the postoperative WBL passed through Fujisawa's point (WBL = 62.5%), and the alignment error was defined as the difference between the postoperative WBL ratio and 62.5. The correlations among the alignment error, the correction error, correction angle during surgery, pre- and postoperative WBL ratio, MPTA, and JLCA and the differences between the pre and postoperative WBL ratio, MPTA, and JLCA were investigated. In addition, the factor most influential on the alignment error was determined. RESULTS: The preoperative MPTA was the only predictor of the alignment error after OWHTO. The alignment error was positively correlated with the correction error and correction angle during surgery, and negatively correlated with pre- and postoperative WBL ratio, MPTA, and differences between the pre- and postoperative WBL ratio and JLCA. CONCLUSION: The preoperative MPTA was the only pre- and intra-operative predictor of the alignment error after OWHTO. The larger the correction angle, the greater the alignment error. The MPTA was recommended as an indicator for improving the correction accuracy. Accurate correction based on the MPTA provides good lower limb alignment and better clinical results. LEVEL OF EVIDENCE: III Case-control study/Retrospective comparative study.

Analyzing Alignment Error in Tibial Tuberosity-Trochlear Groove Distance in Clinical Scans Using 2D and 3D Methods.

BACKGROUND: Tibial tuberosity-trochlear groove distance (TT-TG) is often used as a primary metric for surgical decision-making in the treatment of patellofemoral instability (PFI), particularly when considering tibial tubercle transfer. Although TT-TG has high interrater reliability, it is prone to measurement differences caused by the alignment of the patient's leg in a scanner gantry, potentially influencing surgical decision-making. Quantification of this error within the clinical literature remains limited. PURPOSE: To quantify and specify the error in TT-TG caused by leg-scanner alignment by using detailed topographical landmarks and 3-dimensional (3D) analysis of computed tomography scans of patients with PFI. STUDY DESIGN: Controlled laboratory study. METHODS: Three-dimensional models of knees with PFI were created from computed tomography scans and used to identify TT-TG landmarks. TT-TG was measured using the established 2-dimensional (2D) and 3D methods. A model to estimate the differences between these 2 methods was created, and the orientation of the patients' legs in relation to scanner longitudinal axis was measured to validate this model via linear regression. Interrater reliability was calculated via intraclass correlation coefficients (ICC). RESULTS: A total of 44 knees of patients with PFI were analyzed. Differences between the 2D and 3D methods ranged from -4.0 to 14.7 mm (mean ± SD, 2.7 ± 4.1 mm) with a root mean square difference of 4.8 mm. The TT-TG distance of the 2D method (19.8 ± 7.2 mm) was significantly (P = .045) longer than that of the 3D method (17.1 ± 4.9 mm). The variance of the 2D method was significantly larger than that of the 3D method. In total, 13 (29.5%) of the knees had a difference of >5 mm between 2D and 3D TT-TG. The estimation model had an adjusted r2 value of 1.00 and a resulting root mean square difference of 0.21 mm. 3D TT-TGs interrater reliability was good to excellent (ICC, 0.94 [95 CI%, 0.81-0.98]). CONCLUSION: 3D TT-TG can be used to correct scanner-leg alignment errors, some of which are substantial when using only 2D TT-TG measurements. CLINICAL RELEVANCE: The findings in this study suggest a need for caution and awareness of the potential effects of differences in alignment of the axes of the leg and scanner when using purely 2D TT-TG as a basis for surgical planning.

Skill Differences in a Discrete Motor Task Emerging From the Environmental Perception Phase.

Because of the challenges associated with measuring human perception and strategy, the process of human performance from perception to motion to results is not fully understood. Therefore, this study clarifies the phase at which errors occur and how differences in skill level manifest in a motor task requiring an accurate environmental perception and fine movement control. We assigned a golf putting task and comprehensively examined various errors committed in five phases of execution. Twelve tour professionals and twelve intermediate amateur golfers performed the putting task on two surface conditions: flat and a 0.4-degree incline. The participants were instructed to describe the topographical characteristics of the green before starting the trials on each surface (environmental perception phase). Before each attempt, the participants used the reflective markers to indicate their aim point from which the ball would be launched (decision-making phase). We measured the clubface angle and impact velocity to highlight the pre-motion and motion errors (pre-motion and motion phase). In addition, mistakes in the final ball position were analyzed as result errors (post-performance phase). Our results showed that more than half of the amateurs committed visual-somatosensory errors in the perception phase. Moreover, their aiming angles in the decision-making phase differed significantly from the professionals, with no significant differences between slope conditions. In addition, alignment errors, as reported in previous studies, occurred in the pre-motion phase regardless of skill level (i.e., increased in the 0.4-degree condition). In the motion phase, the intermediate-level amateurs could not adjust their clubhead velocity control to the appropriate level, and the clubhead velocity and clubface angle control were less reproducible than those of the professionals. To understand the amateur result errors in those who misperceived the slopes, we checked the individual results focusing on the final ball position. We found that most of these participants had poor performance, especially in the 0.4-degree condition. Our results suggest that the amateurs' pre-motion and strategy errors depended on their visual-somatosensory errors.

Realization of Three-Dimensionally MEMS Stacked Comb Structures for Microactuators Using Low-Temperature Multi-Wafer Bonding with Self-Alignment Techniques in CMOS-Compatible Processes.

A high-aspect-ratio three-dimensionally (3D) stacked comb structure for micromirror application is demonstrated by wafer bonding technology in CMOS-compatible processes in this work. A vertically stacked comb structure is designed to circumvent any misalignment issues that could arise from multiple wafer bonding. These out-of-plane comb drives are used for the bias actuation to achieve a larger tilt angle for micromirrors. The high-aspect-ratio mechanical structure is realized by the deep reactive ion etching of silicon, and the notching effect in silicon-on-insulator (SOI) wafers is minimized. The low-temperature bonding of two patterned wafers is achieved with fusion bonding, and a high bond strength up to 2.5 J/m2 is obtained, which sustains subsequent processing steps. Furthermore, the dependency of resonant frequency on device dimensions is studied systematically, which provides useful guidelines for future design and application. A finalized device fabricated here was also tested to have a resonant frequency of 17.57 kHz and a tilt angle of 70° under an AC bias voltage of 2 V.

Pitfalls in assessing limb alignment affected by rotation and flexion of the knee after total knee arthroplasty: Analysis using sagittal and coronal whole-body EOS radiography.

BACKGROUND: Inappropriate posture during radiographic assessment may lead to misunderstanding of postoperative alignment after total knee arthroplasty (TKA). The EOS system assesses coronal and sagittal alignment simultaneously. This study aimed to evaluate the effect of flexion and/or rotation on alignment, and identify the patterns of knee posture with serial follow-up using the EOS system. METHODS: One-hundred and fifteen patients of TKA and serial whole-body EOS were included. The hip-knee-ankle (HKA) angle in the coronal and sagittal planes, femoral component rotation ratio (FCR), tibial component rotation ratio (TCR), and fibular overlap ratio (FO) were measured immediately and at six months and one year postoperatively. Total and partial correlation, using flexion and rotation as a control variable was performed. RESULTS: The mean HKA values and flexion immediately post-operation were different compared with the values noted at six months and one year postoperatively (for all, P < 0.05). The FCR and FO were correlated with the HKA angle during all periods (for both, P < 0.05). The Pearson correlation coefficients of the HKA angle with rotation parameters decreased when flexion was controlled. CONCLUSIONS: Combined rotation and flexion of the knee joint has a greater effect on coronal alignment compared with isolated flexion or rotation and was more frequently observed during the early postoperative period. Therefore, surgeons should be made aware of the potential knee rotation and flexion errors after TKA.

A novel miniature robotic guidance device for stereotactic neurosurgical interventions: preliminary experience with the iSYS1 robot.

OBJECTIVE Robotic devices have recently been introduced in stereotactic neurosurgery in order to overcome the limitations of frame-based and frameless techniques in terms of accuracy and safety. The aim of this study is to evaluate the feasibility and accuracy of the novel, miniature, iSYS1 robotic guidance device in stereotactic neurosurgery. METHODS A preclinical phantom trial was conducted to compare the accuracy and duration of needle positioning between the robotic and manual technique in 162 cadaver biopsies. Second, 25 consecutive cases of tumor biopsies and intracranial catheter placements were performed with robotic guidance to evaluate the feasibility, accuracy, and duration of system setup and application in a clinical setting. RESULTS The preclinical phantom trial revealed a mean target error of 0.6 mm (range 0.1-0.9 mm) for robotic guidance versus 1.2 mm (range 0.1-2.6 mm) for manual positioning of the biopsy needle (p < 0.001). The mean duration was 2.6 minutes (range 1.3-5.5 minutes) with robotic guidance versus 3.7 minutes (range 2.0-10.5 minutes) with manual positioning (p < 0.001). Clinical application of the iSYS1 robotic guidance device was feasible in all but 1 case. The median real target error was 1.3 mm (range 0.2-2.6 mm) at entry and 0.9 mm (range 0.0-3.1 mm) at the target point. The median setup and instrument positioning times were 11.8 minutes (range 4.2-26.7 minutes) and 4.9 minutes (range 3.1-14.0 minutes), respectively. CONCLUSIONS According to the preclinical data, application of the iSYS1 robot can significantly improve accuracy and reduce instrument positioning time. During clinical application, the robot proved its high accuracy, short setup time, and short instrument positioning time, as well as demonstrating a short learning curve.

Application of computer navigation in total knee Arthroplasty / 中国组织工程研究

BACKGROUND: With the development of precision medicine, knee replacement under navigation has been paid more and more attention. Precision medicine allows for more accurate implant placement and better limb alignment. However, precision medicine can also make surgery much longer. OBJECTIVE: To evaluate the application of Aesculap Ortho-Pilot non-image-dependent wireless navigation in total knee arthroplasty. METHODS: Data of 42 patients with unilateral knee osteoarthritis admitted to the First Affiliated Hospital of Anhui Medical University from April to November 2017 were retrospectively collected. First total knee arthroplasty was conducted by the same surgeon. According to surgical methods, the patients were divided into two groups: The navigation group (n=21) received a total knee arthroplasty under the assistance of Ortho-Pilot non-image-dependent wireless navigation, and the non-navigation group (n=21) received a regular total knee arthroplasty. Operation time and drainage volume were recorded in both groups. X-ray film of weight bearing was taken 12 months after operation. Mechanical axis of the lower extremity, the mechanical proximal medial proximal angle of the mechanical shaft of the tibia, the distal lateral angle of the femoral mechanical axis, sagittal tibial component angle and the number of alignment deviation of the lower extremity (>3°) were compared between the two groups. Knee range of motion and Hospital for Special Surgery knee score were evaluated. This study was approved by the Ethics Committee of First Affiliated Hospital of Anhui Medical University. RESULTS AND CONCLUSION: (1) Operation time was longer in the navigation group than in the non-navigation group (P 3° and the variables of medial angular separation of proximal end of the mechanical axis of the tibia between the two groups (P > 0.05). (3) At postoperative 12 months, the range of motion was larger in the navigation group than in the non-navigation group (P 0.05). (4) Results suggested that total knee arthroplasty assisted by computer navigation can improve the accuracy of lower limb alignment, accuracy of prosthesis placement and knee range of motion. However, the operation time was improved, so the advantages and disadvantages should be considered comprehensively.