Accuracy Of Rotational Alignment Research Articles

Robot-assisted total knee arthroplasty system provides more precise control of the femoral rotation angle: A retrospective study.

Rotational alignment in total knee arthroplasty (TKA) is a crucial technical point that needs attention. We conducted a retrospective study to investigate whether a new robot-assisted TKA (RA-TKA) could improve the accuracy of rotational alignment and whether rotational alignment affects postoperative pain and functional evaluation of the knee. A total of 136 consecutive patients who underwent TKA were included in this study. Half of the patients underwent RA-TKA and the other half underwent conventional TKA (CON-TKA) by the same group of surgeons. Collect the relevant parameters. The postoperative femoral rotation angle (FRA) was -0.72±2.59° in the robot-assisted group and 1.13±2.73° in the conventional group, and were statistically significantly different (p<0.001). This study provides preliminary evidence that the RA-TKA provides more precise control of FRA than CON-TKA, and verifies that tibial rotation angle and combined rotation angle affect postoperative knee pain and functional evaluation.

Computer-assisted surgery and patient-specific instrumentation improve the accuracy of tibial baseplate rotation in total knee arthroplasty compared to conventional instrumentation: a systematic review and meta-analysis.

To determine whether patient-specific instrumentation (PSI), computer-assisted surgery (CAS) or robot-assisted surgery (RAS) enable more accurate rotational alignment of the tibial baseplate in primary total knee arthroplasty (TKA) compared to conventional instrumentation, in terms of deviation from the planned target and the proportion of outliers from the target zone. The authors independently conducted three structured electronic literature searches using the PubMed, Embase®, and Cochrane Central Register of Controlled Trials databases from 2007 to 2020. Studies were included if they compared rotational alignment of the tibial baseplate during TKA using conventional instrumentation versus PSI, CAS, and/or RAS, and reported deviation from preoperatively planned rotational alignment of the tibial baseplate in terms of absolute angles and/or number of outliers. Methodological quality of eligible studies was assessed by two researchers according to the Downs and Black Quality Checklist for Health Care Intervention Studies. Fifteen studies, that reported on 2925 knees, were eligible for this systematic review, of which 6 studies used PSI, and 9 used CAS. No studies were found for RAS. Of the studies that reported on angular deviation from preoperatively planned rotational alignment, most found smaller deviations using PSI (0.5° to 1.4°) compared to conventional instrumentation (1.0° to 1.6°). All studies that reported on proportions of outliers from a target zone (± 3°), found lower rates of outliers using PSI (0 to 22%) compared to conventional instrumentation (5 to 96%). Most studies reported smaller angular deviation from preoperatively planned rotational alignment using CAS (0.1° to 6.9°) compared to conventional instrumentation (1.1° to 7.8°). Of the studies that reported on proportions of outliers from a target zone (± 3°), most found fewer outliers using CAS (10 to 61%) compared to conventional instrumentation (17 to 78%). This systematic review and meta-analysis revealed that both CAS and PSI can improve the accuracy of rotational alignment of the tibial baseplate by decreasing angular deviation from the preoperatively planned target and reducing the proportion of outliers from the target zone. The clinical relevance is that PSI and CAS can improve alignment, though the thresholds necessary to grant better outcomes and survival remain unclear. IV.

Tibial component coverage and rotational alignment accuracy after mobile-bearing total knee arthroplasty.

Tibial component coverage (TCC) and tibial rotational angle (TRA) have been studied simultaneously in simulations, but not in clinical studies after total knee arthroplasty (TKA). The purposes of this study were (1) to evaluate TCC and rotational setting postoperatively in mobile-bearing TKA patients and (2) to compare the results with previously published simulation data. We prospectively examined 100 patients who underwent primary TKA using the LCS® Total Knee System (LCS) posterior cruciate ligament-substituting prosthesis. Clinical outcomes, TCC (coverage area of the tibial component over the tibia), and TRA (relative to the femoral transepicondylar axis (TEA)) were assessed. Quantitative three-dimensional computed tomography was used to assess TCC and TRA. All values are expressed as median (25th percentile, 75th percentile) using minus (-) for internal and plus (+) for external rotation. Hospital for Special Surgery scores improved from 46 (36, 50) preoperatively to 92 (90, 92) postoperatively. TRA showed a median divergence of -2.0° (-4.75°, +2.74°). All knees were located within 10° of the TEA (range -10.0° to +9.7°). The median TCC of the knees was 82.7% (80.6, 84.7%), and there were no knees that hung over the tibial component in any direction. The LCS prosthesis had good clinical outcomes, comparable TCC, and improved TRA as compared to previous reports, as all knees were located within 10° of the TEA. Simultaneous optimization of both TCC and TRA may contribute to the excellent long-term outcomes that have been observed with this system. Level II, Prognostic study.

Computer-assisted surgery does not improve the rotational alignment of the femoral component in total knee arthroplasty for severe genu varus deformity

Background: Accurate femoral rotational alignment is critical for successful total knee arthroplasty (TKA). Debates exist about whether computer-assisted surgery-TKA (CAS-TKA) improves the accuracy of femoral rotational alignment. We hypothesize that it is related to the severity of the preoperative genu varus deformity and that CAS-TKA is beneficial under certain circumstances. Methods: Patients who had osteoarthritis with genu varus deformity and underwent conventional TKA or CAS-TKA between January 2007 and July 2013 at our hospital were enrolled. Based on the degree of preoperative deviation from the mechanical axis (MA), the patients were divided into three subgroups at 5-degree intervals: (1) varus deformity of ＜ 10 degrees, (2) 10–14.9 degrees, and (3) ≥ 15 degrees. Computed tomography was used to determine whether CAS-TKA provided better femoral rotational alignment than did conventional TKA. Component and limb alignment were also radiographically compared. Results: One hundred seventy-three knees on 128 patients met the inclusion criteria. For patients in the ＜ 10 degrees and 10–14.9 degrees groups, the component alignments and postoperative mechanical axes were not significantly different between conventional and CSA-TKA. For patients in the ≥ 15 degrees group, however, the femoral flexion angle was significantly (p ＜ 0.001) better for CSA-TKA, but not for the femoral valgus, tibial valgus, tibial flexion, or femoral rotational angles. Conclusions: CAS-TKA does not improve the accuracy of rotational alignment of the femoral component in patients with genu varus deformity. Level of Evidence: Therapeutic Level III.

MPO Type 8-Multicore Fiber Connector With Physical Contact Connection

We developed a MPO type 8-multicore fiber (MCF) connector using single mode 7-core MCF and realized physical contact (PC) with return loss more than 40 dB and low connection loss less than 0.85 dB in all 56 cores. To simplify the rotational alignment process for each MCF, we developed the rotational alignment method using alignment member and realized rotational alignment accuracy within ±1°. To reduce necessary pressing force for PC connection of all cores in all MCFs, we utilized compressive strain of MCF cladding for the absorption of height difference among MCFs and polishing for bare MCF to reduce necessary pressing force for a pair of MCFs. Fabricated 8-MCF connector demonstrated all cores PC with pressing force of 18 N.

An Additional Reference Axis Improves Femoral Rotation Alignment in Image-Free Computer Navigation Assisted Total Knee Arthroplasty

Few studies have demonstrated improvement in accuracy of rotational alignment using image-free navigation systems mainly due to the inconsistent registration of anatomical landmarks. We have used an image-free navigation for total knee arthroplasty, which adopts the average algorithm between two reference axes (transepicondylar axis and axis perpendicular to the Whiteside axis) for femoral component rotation control. We hypothesized that addition of another axis (condylar twisting axis measured on a preoperative radiograph) would improve the accuracy. One group using the average algorithm (double-axis group) was compared with the other group using another axis to confirm the accuracy of the average algorithm (triple-axis group). Femoral components were more accurately implanted for rotational alignment in the triple-axis group (ideal: triple-axis group 100%, double-axis group 82%, P<0.05).

Paper 206: Accuracy of Rotational Alignment of Femoral Component in Navigated Total Knee Arthroplasty

Paper 206: Accuracy of Rotational Alignment of Femoral Component in Navigated Total Knee Arthroplasty

High-throughput subtomogram alignment and classification by Fourier space constrained fast volumetric matching

Cryo-electron tomography allows the visualization of macromolecular complexes in their cellular environments in close-to-live conditions. The nominal resolution of subtomograms can be significantly increased when individual subtomograms of the same kind are aligned and averaged. A vital step for such a procedure are algorithms that speedup subtomogram alignment and improve its accuracy to allow reference-free subtomogram classifications. Such methods will facilitate automation of tomography analysis and overall high throughput in the data processing. Building on previous work, here we propose a fast rotational alignment method that uses the Fourier equivalent form of a popular constrained correlation measure that considers missing wedge corrections and density variances in the subtomograms. The fast rotational search is based on 3D volumetric matching, which improves the rotational alignment accuracy in particular for highly distorted subtomograms with low SNR and tilt angle ranges in comparison to fast rotational matching of projected 2D spherical images. We further integrate our fast rotational alignment method in a reference-free iterative subtomogram classification scheme, and propose a local feature enhancement strategy in the classification process. As a proof of principle, we can demonstrate that the automatic method can successfully classify a large number of experimental subtomograms without the need of a reference structure.

Can CT-based patient-matched instrumentation achieve consistent rotational alignment in knee arthroplasty?

Long-term success of contemporary total knee replacements relies to a large extent on proper implant alignment. This study was undertaken to test whether specimen-matched cutting blocks based on computed axial tomography (CT) scans could provide accurate rotational alignment of the femoral component. CT scans of five fresh frozen full leg cadaver specimens, equipped with infrared reflective markers, were used to produce a specimen-matched femoral cutting block. Using those blocks, the bone cuts were made to implant a bi-compartmental femoral component. Rotational alignment of the components in the horizontal plane was determined using an optical measurement system and compared with all relevant rotational reference axes identified on the CT scans. Average rotational alignment for the bi-compartmental component in the horizontal plane was 1.9° (range 0°-6.3°; standard deviation 2.6°). One specimen that showed the highest deviation from the planned alignment also featured a completely degraded medial articular surface. The CT-based specimen-matched cutting blocks achieved good rotational alignment accuracy except for one specimen with badly damaged cartilage. In such cases, imaging techniques that visualize the cartilage layer might be more suitable to design cutting blocks, as they will provide a better fit and increased surface support.

A computed tomography based study on rotational alignment accuracy of the femoral component in total knee arthroplasty using computer-assisted orthopaedic surgery

Rotation of the femoral component in total knee arthroplasty (TKA) is of high importance in respect of the balancing of the knee and the patellofemoral joint. Though it is shown that computer assisted surgery (CAOS) improves the anteroposterior (AP) alignment in TKA, it is still unknown whether navigation helps in finding the accurate rotation or even improving rotation. Therefore the aim of our study was to evaluate the postoperative femoral component rotation on computed tomography (CT) with the intraoperative data of the navigation system. In 20 navigated TKAs the difference between the intraoperative stored rotation data of the femoral component and the postoperative rotation on CT was measured using the condylar twist angle (CTA). This is the angle between the epicondylar axis and the posterior condylar axis. Statistical analysis consisted of the intraclass correlation coefficient (ICC) and Bland-Altman plot. The mean intraoperative rotation CTA based on CAOS was 3.5° (range 2.4–8.6°). The postoperative CT scan showed a mean CTA of 4.0° (1.7–7.2). The ICC between the two observers was 0.81, and within observers this was 0.84 and 0.82, respectively. However, the ICC of the CAOS CTA versus the postoperative CT CTA was only 0.38. Though CAOS is being used for optimising the position of a TKA, this study shows that the (virtual) individual rotational position of the femoral component using a CAOS system is significantly different from the position on a postoperative CT scan.

SU‐GG‐J‐19: Electromagnetic Detection and Real‐Time DMLC Correction of Rotation during Radiotherapy

Purpose: A novel system has been developed to detect and correct tumor rotation in real‐time during radiotherapy delivery. The aim of this study was to quantify the geometric accuracy of the system. Method and Materials: A research Calypso system was integrated with a real‐time DMLC tracking system, employed on a Varian IX linac. Three 3mm diameter tungsten balls (markers) were embedded in the phantom, along with implanted electromagnetic transponders. EPID images were acquired for an elliptical beam, from which the beam aperture and tungsten balls were synchronously observed. For static rotation, the couch was used; for dynamic rotation, the couch was manually rotated continuously from 90 deg to 180 deg through the console. The dynamic rotation experiment was also performed by overlying the EM embedded phantom on a motion platform, rotating with a period of approximately 8 seconds. For all measurements, the beam‐target rotational alignment was determined as the difference between the major axis of the ellipse best fitting the rotated beam aperture and the marker orientation of the rotated target. The beam‐target translation alignment was determined by the different between the beam aperture center and the geometric center of the markers. Results: For static rotation, the beam‐target rotational alignment error was 0.9±1.7°. For dynamic rotation the alignment error was 0.3±1.4°. Both tests demonstrate sub‐degree accuracy for the tracking system. The beam‐target translational alignment error was 0.2±0.2mm. Conclusion: For the first time, real‐time target rotation has been accurately detected and corrected during treatment via MLC adaptation. The beam‐target rotational alignment accuracy is &lt;1 degree; translational alignment is &lt;1mm. The results show promise for improving radiotherapy targeting accuracy for a variety of tumor sites and motion types. Conflict of Interest: Supported by Calypso, NIH R0193626 and Varian.

Inter- and Intra-Observer Errors in Identifying the Transepicondylar Axis and Whiteside's Line

To assess inter- and intra-observer errors in identifying the transepicondylar axis and Whiteside's line in a cadaveric model mimicking total knee arthroplasty. Four cadaveric knees with intact soft tissues were used. The knees were exposed anteriorly using the Insall approach, with the patella everted laterally. Three observers (2 surgeons and one trainee) took turns to identify the anatomic landmarks of the transepicondylar axis and Whiteside's line. Each observer repeated the process 20 times. Each identification was photographed and referenced with the true values obtained from the knees after they were stripped of all soft tissue. Inter- and intra-observer errors in the anatomic landmarks were compared. Inter-observer error was significant with both the transepicondylar axis and Whiteside's line (p<0.001, one-way ANOVA). The intra-observer variation was greater for Whiteside's line than the transepicondylar axis (standard deviation, 4.2 vs 2.5 degrees). The maximum potential errors in the transepicondylar axis and Whiteside's line were 13 degrees and 24 degrees, respectively. The accuracy of rotational alignment of the transepicondylar axis and Whiteside's line were operator-dependent, and their intra-operative reproducibility was low.

Averaging Different Alignment Axes Improves Femoral Rotational Alignment in Computer-Navigated Total Knee Arthroplasty

Computer navigation systems generally establish the rotational alignment axis of the femoral component on the basis of user-defined anatomic landmarks. However, navigation systems can also record knee kinematics and average alignment axes established with multiple techniques. We hypothesized that establishing femoral rotational alignment with the use of kinematic techniques is more accurate and precise (repeatable) than the use of anatomic techniques and that establishing femoral rotational alignment by averaging the results of different alignment techniques is more accurate and precise than the use of a single technique. Twelve orthopaedic surgeons used three anatomic and two kinematic alignment techniques to establish femoral rotational alignment axes in a series of nine cadaver knees. The axes derived with the individual anatomic and kinematic techniques as well as the axes derived with six combination techniques--i.e., those involving averaging of the alignments established with two of the individual techniques--were compared against a reference axis established with computed tomography images of each femur. The kinematic methods were not more accurate (did not have smaller mean errors) or more precise (repeatable) than the anatomic techniques. The combination techniques were accurate (five of the six had a mean error of <5 degrees ) and significantly more precise than all but one of the single methods. The percentage of measurements with <5 degrees of error as compared with the reference epicondylar axis was 37% for the individual anatomic techniques, 30% for the individual kinematic techniques, and 58% for the combination techniques. Averaging the results of kinematic and anatomic techniques, which is possible with computer navigation systems, appears to improve the accuracy of rotational alignment of the femoral component. The number of rotational alignment outliers was reduced when combination techniques were used; however, they are still a problem and continued improvement in methods to accurately establish rotation of the femoral component in total knee arthroplasty is needed.