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 Accuracy of Coronal Plane Mechanical Alignment in a Customized, Individually Made Total Knee Replacement with Patient-Specific Instrumentation

2017 ◽  
Vol 31 (08) ◽  
pp. 792-796 ◽  
Author(s):  
Gary Levengood ◽  
Jack Dupee
Keyword(s):  
Mechanical Axis ◽  
Computer Assisted Surgery ◽  
Coronal Plane ◽  
Patient Specific ◽  
Computer Assisted ◽  
Consecutive Series ◽  
Mechanical Alignment ◽  
Patient Specific Instrumentation ◽  
Patient Specific Instruments ◽  
Total Knee

AbstractThe objective of this study was to evaluate the accuracy of a customized individually made total knee implant used in conjunction with patient-specific cutting guides in restoring coronal plane mechanical axis alignment using computer-assisted surgery (CAS). A consecutive series of 63 total knee arthroplasty (TKA) patients were prospectively measured with intraoperative CAS. The patient-specific instruments and implants were created utilizing a preoperative CT scan. CAS system was used for all patients, to determine mechanical alignment. Bone cuts were made using the patient-specific instruments. Both bone cuts and final coronal mechanical alignment were recorded utilizing the navigation system for the assessment.The patient-specific instruments and implants provided perfect neutral coronal mechanical alignment (0°) in 53 patients. The remaining 10 patients had a postoperative alignment within ± 2° of neutral. The average preoperative deformity was 5.57° versus 0.18° postoperatively (p < 0.0001). The mean correction angle was 5.68°. No patients had postoperative extension deficits as measured with CAS (7.50° pre-op for 40/63 patients). Customized, individually made total knee implant with patient-specific cutting jigs showed results that are comparable to those of CAS systems in this study. This technology restores the neutral coronal mechanical axis very accurately, while offering unique benefits such as improved implant fit and restoration of the patient's J-curves, which require further investigation.

A randomized controlled trial of tibial component migration with kinematic alignment using patient-specific instrumentation versus mechanical alignment using computer-assisted surgery in total knee arthroplasty

2019 ◽  
Vol 101-B (8) ◽  
pp. 929-940 ◽  
Author(s):  
E. K. Laende ◽  
C. G. Richardson ◽  
M. J. Dunbar
Keyword(s):  
Tibial Component ◽  
Computer Assisted Surgery ◽  
Patient Specific ◽  
Kinematic Alignment ◽  
Computer Assisted ◽  
Randomized Controlled ◽  
Patient Specific Instrumentation ◽  
Total Knee ◽  
Male Patients ◽  
Component Migration

Aims Patient-specific instrumentation of total knee arthroplasty (TKA) is a technique permitting the targeting of individual kinematic alignment, but deviation from a neutral mechanical axis may have implications on implant fixation and therefore survivorship. The primary objective of this randomized controlled study was to compare the fixation of tibial components implanted with patient-specific instrumentation targeting kinematic alignment (KA+PSI) versus components placed using computer-assisted surgery targeting neutral mechanical alignment (MA+CAS). Tibial component migration measured by radiostereometric analysis was the primary outcome measure (compared longitudinally between groups and to published acceptable thresholds). Secondary outcome measures were inducible displacement after one year and patient-reported outcome measures (PROMS) over two years. The secondary objective was to assess the relationship between alignment and both tibial component migration and inducible displacement. Patients and Methods A total of 47 patients due to undergo TKA were randomized to KA+PSI (n = 24) or MA+CAS (n = 23). In the KA+PSI group, there were 16 female and eight male patients with a mean age of 64 years (sd 8). In the MA+CAS group, there were 17 female and six male patients with a mean age of 63 years (sd 7). Surgery was performed using cemented, cruciate-retaining Triathlon total knees with patellar resurfacing, and patients were followed up for two years. The effect of alignment on tibial component migration and inducible displacement was analyzed irrespective of study group. Results There was no difference over two years in longitudinal migration of the tibial component between the KA+PSI and MA+CAS groups (reaching median maximum total point motion migration at two years of 0.40 mm for the KA+PSI group and 0.37 mm for the MA+CAS group, p = 0.82; p = 0.68 adjusted for age, sex, and body mass index (BMI) for all follow-ups). Both groups had mean migrations below acceptable thresholds. There was no difference in inducible displacement (p = 0.34) or PROMS (p = 0.61 for the Oxford Knee Score) between groups. There was no correlation between alignment and tibial component migration or alignment and inducible displacement. These findings support non-neutral alignment as a viable option with this component, with no evidence that it compromises fixation. Conclusion Kinematic alignment using patient-specific instrumentation in TKA was associated with acceptable tibial component migration, indicating stable fixation. These results are supportive of future investigations of kinematic alignment. Cite this article: Bone Joint J 2019;101-B:929–940.

Clinical Study of 3D Imaging and 3D Printing Technique for Patient-Specific Instrumentation in Total Knee Arthroplasty

2017 ◽  
Vol 30 (08) ◽  
pp. 822-828 ◽  
Author(s):  
Fei Liu ◽  
Bensen Tang ◽  
Biyong Deng ◽  
Fang Liu ◽  
Weimin Zhu ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
3D Printing ◽  
Knee Arthroplasty ◽  
Tibial Component ◽  
Patient Specific ◽  
Control Group ◽  
Patient Specific Instrumentation ◽  
Printing Technique ◽  
Total Knee ◽  
3D Printing Technique

AbstractPatient-specific instrumentation (PSI) was designed to improve the accuracy of preoperative planning and postoperative prosthesis positioning in total knee arthroplasty (TKA). However, better understanding needs to be achieved due to the subtle nature of the PSI systems. In this study, 3D printing technique based on the image data of computed tomography (CT) has been utilized for optimal controlling of the surgical parameters. Two groups of TKA cases have been randomly selected as PSI group and control group with no significant difference of age and sex (p > 0.05). The PSI group is treated with 3D printed cutting guides whereas the control group is treated with conventional instrumentation (CI). By evaluating the proximal osteotomy amount, distal osteotomy amount, valgus angle, external rotation angle, and tibial posterior slope angle of patients, it can be found that the preoperative quantitative assessment and intraoperative changes can be controlled with PSI whereas CI is relied on experience. In terms of postoperative parameters, such as hip-knee-ankle (HKA), frontal femoral component (FFC), frontal tibial component (FTC), and lateral tibial component (LTC) angles, there is a significant improvement in achieving the desired implant position (p < 0.05). Assigned from the morphology of patients' knees, the PSI represents the convergence of congruent designs with current personalized treatment tools. The PSI can achieve less extremity alignment and greater accuracy of prosthesis implantation compared against control method, which indicates potential for optimal HKA, FFC, and FTC angles.

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