scholarly journals Effect of surgical parameters on the biomechanical behaviour of bicondylar total knee endoprostheses – A robot-assisted test method based on a musculoskeletal model

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
M. Kebbach ◽  
R. Grawe ◽  
A. Geier ◽  
E. Winter ◽  
P. Bergschmidt ◽  
...  
Keyword(s):  
Contact Force ◽  
Tibial Component ◽  
Tibial Slope ◽  
Test Method ◽  
Patient Specific ◽  
Robot Assisted ◽  
Multibody Model ◽  
Total Knee ◽  
The Impact ◽  
Femoral Rollback

Abstract The complicated interplay of total knee replacement (TKR) positioning and patient-specific soft tissue conditions still causes a considerable number of unsatisfactory outcomes. Therefore, we deployed a robot-assisted test method, in which a six-axis robot moved and loaded a bicondylar cruciate-retaining (CR)-TKR in a virtual lower extremity emulated by a musculoskeletal multibody model. This enabled us to systematically analyse the impact of the posterior cruciate ligament (PCL), tibial slope, and tibial component rotation on TKR function while considering the physical implant components and physiological-like conditions during dynamic motions. The PCL resection yielded a decrease of femoral rollback by 4.5 mm and a reduction of tibiofemoral contact force by 50 N. A reduced tibial slope led to an increase of tibiofemoral contact force by about 170 N and a decrease of femoral rollback up to 1.7 mm. Although a higher tibial slope reduced the contact force, excessive tibial slopes should be avoided to prevent joint instability. Contrary to an external rotation of the tibial component, an internal rotation clearly increased the contact force and lateral femoral rollback. Our data contribute to improved understanding the biomechanics of TKRs and show the capabilities of the robot-assisted test method based on a musculoskeletal multibody model as a preoperative planning tool.

scholarly journals Intra-Operative Experience using Magnetic Resonance Imaging (MRI) Based Patient Specific Cutting Guides during Total Knee Arthroplasty

2016 ◽  
Vol 9 (2) ◽  
pp. 22-26
Author(s):  
Ryan K. Albrecht ◽  
Alexander C.M. Chong ◽  
Paul H. Wooley ◽  
Tarun Bhargava
Keyword(s):  
Total Knee Arthroplasty ◽  
Magnetic Resonance ◽  
Knee Arthroplasty ◽  
Total Joint Replacement ◽  
Tibial Slope ◽  
New Technique ◽  
Patient Specific ◽  
Cutting Guides ◽  
Total Knee ◽  
Operative Experience

Background. The incidence of malalignment in total knee arthroplasty(TKA) using conventional instrument has beenreported as high as 25%. A relatively new TKA system involvesthe use of a preoperative magnetic resonance image(MRI) to obtain accurate implant placement more consistently.For broad acceptance of this new technique, it iscrucial to analyze the initial intra-operative experience. Thespecific aim of this study was to evaluate the initial intra-operativeexperience of a single surgeon using this new technique. Methods. A total of 15 knees (12 patients: 6 female and 6male) were reviewed from TKA procedures using the selectedmanufacturer’s patient specific cutting guides between January2011 and April 2013 at a single institution. Patient demographicand specific parameters and intra-operative alterationsof component positioning were recorded and evaluated.Results. The preoperative plan was able to predict correctly thesize of the implanted femoral component in 87% (n = 13) andtibial component in 80% (n = 12) of the cases. However, 60% (n= 9) of cases required additional intra-operative corrections onfemoral resection, and 73% (n = 11) required an additional 2 - 4mm correction on the tibial proximal resection. Twenty percent(n = 3) required additional tibial varus/valgus correction, butthere were no tibial slope corrections for any of the 15 cases. Conclusions. The initial intra-operative experience of a singlesurgeon using current patient specific cutting guides for a selectedmanufacturer to align femoral and tibial components duringTKA has raised some concerns. We agreed with previous studiesthat caution should be taken when using patient specific cuttingguides without supportive data. The findings of this study providedadditional evidence to contest the accuracy of patient specificcutting guides with respect to the initial experience of an orthopaedicsurgeon who is trained in total joint replacement. Theresults provided more evidence to assist orthopaedic surgeonsin the decision of whether to use these patient specific systemsversus conventional TKA methods. KS J Med 2016;9(2):22-26.

scholarly journals Accuracy of Patient Specific Cutting Blocks in Total Knee Arthroplasty

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Naeder Helmy ◽  
Mai Lan Dao Trong ◽  
Stefanie P. Kühnel
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Computer Assisted Surgery ◽  
Tibial Slope ◽  
Patient Specific ◽  
Computer Assisted ◽  
Success Rates ◽  
Term Survival ◽  
Margin Of Error ◽  
Total Knee

Background.Long-term survival of total knee arthroplasty (TKA) is mainly determined by optimal positioning of the components and prosthesis alignment. Implant positioning can be optimized by computer assisted surgery (CAS). Patient specific cutting blocks (PSCB) seem to have the potential to improve component alignment compared to the conventional technique and to be comparable to CAS.Methods.113 knees were selected for PSI and included in this study. Pre- and postoperative mechanical axis, represented by the hip-knee-angle (HKA), the proximal tibial angle (PTA), the distal femoral angle (DFA), and the tibial slope (TS) were measured and the deviation from expected ideal values was calculated.Results.With a margin of error of ±3°, success rates were 81.4% for HKA, 92.0% for TPA, and 94.7% for DFA. With the margin of error for alignments extended to ±4°, we obtained a success rate of 92.9% for the HKA, 98.2% for the PTA, and 99.1% for the DFA. The TS showed postoperative results of 2.86 ± 2.02° (mean change 1.76 ± 2.85°).Conclusion.PSCBs for TKA seem to restore the overall leg alignment. Our data suggest that each individual component can be implanted accurately and the results are comparable to the ones in CAS.

scholarly journals Patient-specific instrumentation for total knee arthroplasty

2017 ◽  
Vol 25 (1) ◽  
pp. 230949901668475 ◽  
Author(s):  
Arash Nabavi ◽  
Caroline M Olwill ◽  
Mike Do ◽  
Tanya Wanasawage ◽  
Ian A Harris
Keyword(s):  
Ct Scan ◽  
Femoral Component ◽  
Tibial Component ◽  
Preoperative Planning ◽  
Coronal Plane ◽  
Patient Specific ◽  
Excellent Outcome ◽  
Patient Specific Instrumentation ◽  
Total Knee ◽  
Sagittal Orientation

Purpose: To assess the accuracy of total knee replacements (TKRs) performed using CT-based patient-specific instrumentation by postoperative CT scan. Method: Approval from the Ethics Committee was granted prior to commencement of this study. Fifty prospective and consecutive patients who had undergone TKR (Evolis, Medacta International) using CT-based patient-specific instrumentation (MY KNEE, Medacta International) were assessed postoperatively using a CT scan and the validated Perth protocol measurement technique. The hip-knee-ankle (HKA) angle of the lower limb in the coronal plane; the coronal, sagittal, and rotational orientation of the femoral component; and the coronal and sagittal orientation of the tibial component were measured. These results were then compared to each patient’s preoperative planning. The percentage of patients found to be less than or equal to 3° of planned alignment was calculated. One patient was excluded as the femoral cutting block did not fit the femur as predicted by planning and therefore underwent a conventional TKR. Results: Ninety-eight percent of patients were within 3° of planned alignment in the coronal plane reproducing the predicted HKA angle. Predicted coronal plane orientation of the tibial and femoral component was achieved in 100% and 96% of patients, respectively. The sagittal orientation of the femoral component was within 3° in 98% of patients. The planned sagittal positioning of the tibial component was achieved in 92% of patients. Furthermore, 90% of patients were found to have a femoral rotation within 3° of planning. Eighty-six percent of patients achieved good-to-excellent outcome at 12 months (Oxford Knee Score > 34). Conclusion: We have found that TKR using this patient-specific instrumentation accurately reproduces preoperative planning in all six of the parameters measured in this study.

scholarly journals Accurate implant fit and leg alignment after cruciate-retaining patient-specific total knee arthroplasty

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Jörg Arnholdt ◽  
Yama Kamawal ◽  
Konstantin Horas ◽  
Boris M. Holzapfel ◽  
Fabian Gilbert ◽  
...  
Keyword(s):  
Knee Arthroplasty ◽  
Tibial Slope ◽  
Joint Line ◽  
Patient Specific ◽  
Cruciate Retaining ◽  
Custom Made ◽  
Ankle Angle ◽  
Total Knee ◽  
Replacement System ◽  
Hip Knee Ankle Angle

Abstract Background For improved outcomes in total knee arthroplasty (TKA) correct implant fitting and positioning are crucial. In order to facilitate a best possible implant fitting and positioning patient-specific systems have been developed. However, whether or not these systems allow for better implant fitting and positioning has yet to be elucidated. For this reason, the aim was to analyse the novel patient-specific cruciate retaining knee replacement system iTotal™ CR G2 that utilizes custom-made implants and instruments for its ability to facilitate accurate implant fitting and positioning including correction of the hip-knee-ankle angle (HKA). Methods We assessed radiographic results of 106 patients who were treated with the second generation of a patient-specific cruciate retaining knee arthroplasty using iTotal™ CR G2 (ConforMIS Inc.) for tricompartmental knee osteoarthritis (OA) using custom-made implants and instruments. The implant fit and positioning as well as the correction of the mechanical axis (hip-knee-ankle angle, HKA) and restoration of the joint line were determined using pre- and postoperative radiographic analyses. Results On average, HKA was corrected from 174.4° ± 4.6° preoperatively to 178.8° ± 2.2° postoperatively and the coronal femoro-tibial angle was adjusted on average 4.4°. The measured preoperative tibial slope was 5.3° ± 2.2° (mean +/− SD) and the average postoperative tibial slope was 4.7° ± 1.1° on lateral views. The joint line was well preserved with an average modified Insall-Salvati index of 1.66 ± 0.16 pre- and 1.67 ± 0.16 postoperatively. The overall accuracy of fit of implant components was decent with a measured medial overhang of more than 1 mm (1.33 mm ± 0.32 mm) in 4 cases only. Further, a lateral overhang of more than 1 mm (1.8 mm ± 0.63) (measured in the anterior-posterior radiographs) was observed in 11 cases, with none of the 106 patients showing femoral notching. Conclusion The patient-specific iTotal™ CR G2 total knee replacement system facilitated a proper fitting and positioning of the implant components. Moreover, a good restoration of the leg axis towards neutral alignment was achieved as planned. Nonetheless, further clinical follow-up studies are necessary to validate our findings and to determine the long-term impact of using this patient- specific system.

scholarly journals How to Quantitatively Balance a Total Knee? A Surgical Algorithm to Assure Balance and Control Alignment

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 700
Author(s):  
Ryan E. Moore ◽  
Michael A. Conditt ◽  
Martin W. Roche ◽  
Matthias A. Verstraete
Keyword(s):  
Soft Tissue ◽  
Surgical Navigation ◽  
Surgical Correction ◽  
Patient Specific ◽  
Popliteus Tendon ◽  
Limb Alignment ◽  
Coronal Alignment ◽  
Total Knee ◽  
The Impact ◽  
Surgical Corrections

To achieve a balanced total knee, various surgical corrections can be performed, while intra-operative sensors and surgical navigation provide quantitative, patient-specific feedback. To understand the impact of these corrections, this paper evaluates the quantitative impact of both soft tissue releases and bone recuts on knee balance and overall limb alignment. This was achieved by statistically analyzing the alignment and load readings before and after each surgical correction performed on 479 consecutive primary total knees. An average of three surgical corrections were required following the initial bone cuts to achieve a well aligned, balanced total knee. Various surgical corrections, such as an arcuate release or increasing the tibial polyethylene insert thickness, significantly affected the maximum terminal extension. The coronal alignment was significantly impacted by pie-crusting the MCL, adding varus to the tibia, or releasing the arcuate ligament or popliteus tendon. Each surgical correction also had a specific impact on the intra-articular loads in flexion and/or extension. A surgical algorithm is presented that helps achieve a well-balanced knee while maintaining the sagittal and coronal alignment within the desired boundaries. This analysis additionally indicated the significant effect that soft tissue adjustments can have on the limb alignment in both anatomical planes.

scholarly journals Total knee arthroplasty: posterior tibial slope influences the size but not the rotational alignment of the tibial component

2020 ◽  
Vol 28 (12) ◽  
pp. 3899-3905
Author(s):  
Petros Ismailidis ◽  
Valerie Kremo ◽  
Annegret Mündermann ◽  
Magdalena Müller-Gerbl ◽  
Andrej Maria Nowakowski
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Tibial Component ◽  
Tibial Slope ◽  
Rotational Alignment ◽  
Posterior Tibial Slope ◽  
Posterior Tibial ◽  
Total Knee
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