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 Achieving a Balanced Knee in Robotic TKA

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 535
Author(s):  
Alexander C Gordon ◽  
Michael A Conditt ◽  
Matthias A Verstraete
Keyword(s):  
Soft Tissue ◽  
Real Time ◽  
Consecutive Series ◽  
Component Position ◽  
Coronal Alignment ◽  
Robotic Assisted ◽  
Primary Tkas ◽  
Wide Range ◽  
Total Knee ◽  
Surgical Corrections

Total knee arthroplasty (TKA) surgery with manual instruments provides a quantitatively balanced knee in approximately 50% of cases. This study examined the effect of combining robotics technology with real-time intra-operative sensor feedback on the number of quantitatively balanced cases in a consecutive series of 200 robotic-assisted primary TKAs. The robotics platform was used to plan the implant component position using correctable poses in extension and a manual, centrally pivoting the balancer in flexion, prior to committing to the femoral cuts. During the initial trialing, the quantitative state of balance was assessed using an instrumented tibial tray that measured the intra-articular loads in the medial and lateral compartments. These sensor readings informed a number of surgical corrections, including bone recuts, soft-tissue corrections, and cement adjustments. During initial trialing, a quantitatively balanced knee was achieved in only 65% of cases. After performing the relevant soft-tissue corrections, bone recuts, and cement adjustments, 87% of cases ended balanced through the range of motion. Meanwhile, this resulted in a wide range of coronal alignment conditions, ranging from 6° valgus to 9° varus. It is therefore concluded that gaps derived from robotics navigation are not indicative for a quantitatively balanced knee, which was only consistently achieved when combining the robotics platform with real-time feedback from intra-operative load sensors.

Functional Outcomes and Accuracy of Patient-Specific Instruments for Total Knee Arthroplasty

2018 ◽  
Vol 25 (5) ◽  
pp. 470-475 ◽  
Author(s):  
Andrea H. Stone ◽  
Udai S. Sibia ◽  
James H. MacDonald
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Functional Outcomes ◽  
Patient Specific ◽  
Consecutive Series ◽  
Coronal Alignment ◽  
Patient Specific Instrumentation ◽  
Estimated Blood Loss ◽  
Patient Specific Instruments ◽  
Total Knee

Background. Patient-specific instruments (PSIs) were developed to improve mechanical axis alignment for patients undergoing total knee arthroplasty (TKA) as neutral alignment (180°) is a predictor of long-term success. This study examines alignment accuracy and functional outcomes of PSI as compared with standard instruments (SIs). Methods. We retrospectively reviewed a consecutive series of TKA procedures using PSI. A total of 85 PSI procedures were identified, and these were compared with a matched cohort of 85 TKAs using SI. Intraoperative decision-making, estimated blood loss, efficiency, Knee Society Scores, and postoperative radiographs were evaluated. Results. One hundred and seventy patients with comparable patient demographics were reviewed. Eighty-one percent of the PSI procedures were within target (180 ± 3°) mechanical alignment, while the SI group had 70% of cases within the target plane ( P = .132). Mean target alignment (2.0° PSI vs 2.2° SI, P = .477) was similar between groups. Twenty-seven percent of patients in the PSI group had surgeon-directed intraoperative recuts to improve the perceived coronal alignment. The change in hematocrit was reduced in the PSI group (8.89 vs 7.21, P = .000). Procedure time and total operating room time were equivalent. Knee Society Scores did not differ between groups at 6 months or at 1 year. Conclusion. Patient-specific instrumentation decreased change in hematocrit, though coronal alignment and efficiency were equivalent between groups. Surgeons must evaluate cuts intraoperatively to confirm alignment. Functional outcomes are equivalent for PSI and SI groups.

Total knee arthroplasty with patient-specific instruments improves function and restores limb alignment in patients with extra-articular deformity

The Knee ◽  
2013 ◽  
Vol 20 (6) ◽  
pp. 407-411 ◽  
Author(s):  
Emmanuel Thienpont ◽  
Frederic Paternostre ◽  
Martin Pietsch ◽  
Mahmoud Hafez ◽  
Stephen Howell
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Patient Specific ◽  
Limb Alignment ◽  
Patient Specific Instruments ◽  
Total Knee

Balancing of total knee arthroplasty by bone cuts achieves accurately balanced soft tissues without the need for soft tissue releases

2018 ◽  
Vol 3 (5) ◽  
pp. 263-268 ◽  
Author(s):  
Ponky Firer ◽  
Brad Gelbart
Keyword(s):  
Total Knee Arthroplasty ◽  
Patient Satisfaction ◽  
Soft Tissue ◽  
Knee Arthroplasty ◽  
Soft Tissues ◽  
Size Difference ◽  
Gap Size ◽  
X Rays ◽  
Coronal Alignment ◽  
Total Knee

IntroductionPatient satisfaction, after mechanically aligned Total Knee Arthroplasty (TKA) is only 80%-85%. There is an inabilty to consistently get perfect soft tissue balance with this technique. It is postulated that soft tissue balance within 2° can be achieved by the boney cuts (Bone Balancing) without soft tissue releases, accepting whatever coronal mechanical alignment (CMA) this produces; that the alignment produced would be similar to natural (constitutional) alignment and that balanced knees would improve patient satisfaction.MethodsWe report on 914 consecutive TKAs using Bone Balancing: the femoral rotation for the flexion gap; the distal femoral cut and valgus angle for the extension gap are adjusted to give equal gap sizes with soft tissue balanced within 2° of medio-lateral laxity. Long leg X-rays were used to measure post-operative coronal alignment. Satisfaction beyond 1 year post operation was assessed by an independent researcher, using a question on satisfaction and a VAS score.Results782(85.5%) TKAs with satisfactory x-rays were available at 2-7 years follow up. Their CMA had a similar distribution profile to reported natural alignment studies. Of these, 672 (86%) had a CMA of 0°±3° (’aligned' group). Overall patient satisfaction was 92.8%, with satisfied patients having a mean (range) VAS score of 9.53 (7.3-10.0) and the dissatisfied patients 3.78 (0.0-6.3) (p<0.0001). There was no difference in satisfaction between ’aligned' knees (92.7%) and those ’outliers', whose CMA was >±3° (93.6%) (p=0.853). All balance measurements were within 3° with 92.2% being ≤2°. Gap size difference between extension and 90° flexion was ≤2mm in 98.7% of cases. Midflexion (45° flexion) balance was within 3° in all cases and the gap size difference was ≤2mm in 89%.ConclusionBalancing by bone cuts is able to achieve accurately balanced soft tissues without the need for soft tissue releases. The coronal alignment profile produced matches that of the normal population. This technique improves satisfaction compared to the literature for mechanically aligned TKAs. Acurate and measured soft tissue balancing needs further consideration in TKAs.Level of EvidenceLevel IV.

scholarly journals Patient-specific instrumentation improved three-dimensional accuracy in total knee arthroplasty: a comparative radiographic analysis of 1257 total knee arthroplasties

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Leo Pauzenberger ◽  
Martin Munz ◽  
Georg Brandl ◽  
Julia K. Frank ◽  
Philipp R. Heuberer ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Mechanical Axis ◽  
Three Dimensional ◽  
Mobile Bearing ◽  
Patient Specific ◽  
Limb Alignment ◽  
Patient Specific Instrumentation ◽  
Conventional Instrumentation ◽  
Total Knee

Abstract Background The purpose of this study was to compare restoration of mechanical limb alignment and three-dimensional component-positioning between conventional and patient-specific instrumentation in total knee arthroplasty. Methods Radiographic data of patients undergoing mobile-bearing total knee arthroplasty (n = 1257), using either conventional (n = 442) or patient-specific instrumentation (n = 812), were analyzed. To evaluate accuracy of axis restoration and 3D-component-positioning between conventional and patient-specific instrumentation, absolute deviations from the targeted neutral mechanical limb alignment and planned implant positions were determined. Measurements were performed on standardized coronal long-leg and sagittal knee radiographs. CT-scans were evaluated for accuracy of axial femoral implant rotation. Outliers were defined as deviations from the targeted neutral mechanical axis of > ± 3° or from the intraoperative component-positioning goals of > ± 2°. Deviations greater than ± 5° from set targets were considered to be severe outliers. Results Deviations from a neutral mechanical axis (conventional instrumentation: 2.3°± 1.7° vs. patient-specific instrumentation: 1.7°± 1.2°; p < 0.001) and numbers of outliers (conventional instrumentation: 25.8% vs. patient-specific instrumentation: 10.1%; p < 0.001) were significantly lower in the patient-specific instrumentation group. Significantly lower mean deviations and less outliers were detected regarding 3D-component-positioning in the patient-specific instrumentation compared to the conventional instrumentation group (all p < 0.05). Conclusions Patient-specific instrumentation prevented from severe limb malalignment and component-positioning outliers (> ± 5° deviation). Use of patient-specific instrumentation proved to be superior to conventional instrumentation in achieving more accurate limb alignment and 3D-component positioning, particularly regarding femoral component rotation. Furthermore, the use of patient-specific instrumentation successfully prevented severe (> 5° deviation) outliers.

Sign in / Sign up

Export Citation Format

Share Document