Calipered Kinematic Alignment Using Patient-Specific Instrumentation

2022 ◽  
pp. 29-38
Author(s):  
Ankit Bansal ◽  
David Craig Loucks ◽  
Robert Greenhow ◽  
Russell Presley Swann
Keyword(s):  
Patient Specific ◽  
Kinematic Alignment ◽  
Patient Specific Instrumentation

scholarly journals Restricted Kinematic Alignment, the Fundamentals, and Clinical Applications

2021 ◽  
Vol 8 ◽  
Author(s):  
Pascal-André Vendittoli ◽  
Sagi Martinov ◽  
William G. Blakeney
Keyword(s):  
Lower Limb ◽  
Soft Tissues ◽  
Computer Navigation ◽  
Patient Specific ◽  
Control Group ◽  
Kinematic Alignment ◽  
Knee Anatomy ◽  
Normal Knee ◽  
Patient Specific Instrumentation ◽  
Patient Reported

Introduction: After a better understanding of normal knee anatomy and physiology, the Kinematic Alignment (KA) technique was introduced to improve clinical outcomes of total knee arthroplasty (TKA). The goal of the KA technique is to restore the pre-arthritic constitutional lower limb alignment of the patient. There is, however, a large range of normal knee anatomy. Unusual anatomies may be biomechanically inferior and affect TKA biomechanics and wear patterns. In 2011, the leading author proposed the restricted kinematic alignment (rKA) protocol, setting boundaries to KA for patients with an outlier or atypical knee anatomy.Material and Equipment: rKA aims to reproduce the constitutional knee anatomy of the patient within a safe range. Its fundamentals are based on sound comprehension of lower limb anatomy variation. There are five principles describing rKA: (1) Combined lower limb coronal orientation should be ± 3° of neutral; (2) Joint line orientation coronal alignment should be within ± 5° of neutral; (3) Natural knee's soft tissues tension/ laxities should be preserved/restored; (4) Femoral anatomy preservation is prioritized; (5) The unloaded/most intact knee compartment should be resurfaced and used as the pivot point when anatomical adjustment is required. An algorithm was developed to facilitate the decision-making.Methods: Since ~50% of patients will require anatomic modification to fit within rKA boundaries, rKA is ideally performed with patient-specific instrumentation (PSI), intra-operative computer navigation or robotic assistance. rKA surgical technique is presented in a stepwise manner, following the five principles in the algorithm.Results: rKA produced excellent mid-term clinical results in cemented or cementless TKA. Gait analysis showed that rKA TKA patients had gait patterns that were very close to a non-operated control group, and these kinematics differences translated into significantly better postoperative patient-reported scores than mechanical alignment (MA) TKA cases.Discussion: Aiming to improve the results of MA TKA, rKA protocol offers a satisfactory compromise that recreates patients' anatomy in most cases, omitting the need for extensive corrections and soft tissue releases that are often required with MA. Moreover, it precludes the reproduction of extreme anatomies seen with KA.

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.

Computed Tomography-Based Patient-Specific Instrumentation Loses Accuracy with Significant Varus Preoperative Misalignment

2020 ◽  
Author(s):  
Vicente Jesús León-Muñoz ◽  
Mirian López-López ◽  
Alonso José Lisón-Almagro ◽  
Francisco Martínez-Martínez ◽  
Fernando Santonja-Medina
Keyword(s):  
Computed Tomography ◽  
Deformity Correction ◽  
Patient Specific ◽  
Control Group ◽  
X Rays ◽  
Varus Alignment ◽  
Patient Specific Instrumentation ◽  
Conventional Instrumentation ◽  
The Mean ◽  
Valgus Alignment

AbstractPatient-specific instrumentation (PSI) has been introduced to simplify and make total knee arthroplasty (TKA) surgery more precise, effective, and efficient. We performed this study to determine whether the postoperative coronal alignment is related to preoperative deformity when computed tomography (CT)-based PSI is used for TKA surgery, and how the PSI approach compares with deformity correction obtained with conventional instrumentation. We analyzed pre-and post-operative full length standing hip-knee-ankle (HKA) X-rays of the lower limb in both groups using a convention > 180 degrees for valgus alignment and < 180 degrees for varus alignment. For the PSI group, the mean (± SD) pre-operative HKA angle was 172.09 degrees varus (± 6.69 degrees) with a maximum varus alignment of 21.5 degrees (HKA 158.5) and a maximum valgus alignment of 14.0 degrees. The mean post-operative HKA was 179.43 degrees varus (± 2.32 degrees) with a maximum varus alignment of seven degrees and a maximum valgus alignment of six degrees. There has been a weak correlation among the values of the pre- and postoperative HKA angle. The adjusted odds ratio (aOR) of postoperative alignment outside the range of 180 ± 3 degrees was significantly higher with a preoperative varus misalignment of 15 degrees or more (aOR: 4.18; 95% confidence interval: 1.35–12.96; p = 0.013). In the control group (conventional instrumentation), this loss of accuracy occurs with preoperative misalignment of 10 degrees. Preoperative misalignment below 15 degrees appears to present minimal influence on postoperative alignment when a CT-based PSI system is used. The CT-based PSI tends to lose accuracy with preoperative varus misalignment over 15 degrees.

scholarly journals True Kinematic Alignment Is Applicable in 44% of Patients Applying Restrictive Indication Criteria—A Retrospective Analysis of 111 TKA Using Robotic Assistance

2021 ◽  
Vol 11 (7) ◽  
pp. 662
Author(s):  
Kim Huber ◽  
Bernhard Christen ◽  
Sarah Calliess ◽  
Tilman Calliess
Keyword(s):  
Soft Tissue ◽  
Retrospective Analysis ◽  
Patient Specific ◽  
Kinematic Alignment ◽  
Postoperative Phase ◽  
Robotic Assistance ◽  
Component Position ◽  
Joint Stability ◽  
Robotic Assisted ◽  
Primary Tkas

Introduction: Image-based robotic assistance appears to be a promising tool for individualizing alignment in total knee arthroplasty (TKA). The patient-specific model of the knee enables a preoperative 3D planning of component position. Adjustments to the individual soft-tissue situation can be done intraoperatively. Based on this, we have established a standardized workflow to implement the idea of kinematic alignment (KA) for robotic-assisted TKA. In addition, we have defined limits for its use. If these limits are reached, we switch to a restricted KA (rKA). The aim of the study was to evaluate (1) in what percentage of patients a true KA or an rKA is applicable, (2) whether there were differences regarding knee phenotypes, and (3) what the differences of philosophies in terms of component position, joint stability, and early patient outcome were. Methods: The study included a retrospective analysis of 111 robotic-assisted primary TKAs. Based on preoperative long leg standing radiographs, the patients were categorized into a varus, valgus, or neutral subgroup. Initially, all patients were planned for KA TKA. When the defined safe zone had been exceeded, adjustments to an rKA were made. Intraoperatively, the alignment of the components and joint gaps were recorded by robotic software. Results and conclusion: With our indication for TKA and the defined boundaries, “only” 44% of the patients were suitable for a true KA with no adjustments or soft tissue releases. In the varus group, it was about 70%, whereas it was 0% in the valgus group and 25% in the neutral alignment group. Thus, significant differences with regard to knee morphotypes were evident. In the KA group, a more physiological knee balance reconstructing the trapezoidal flexion gap (+2 mm on average laterally) was seen as well as a closer reconstruction of the surface anatomy and joint line in all dimensions compared to rKA. This resulted in a higher improvement in the collected outcome scores in favor of KA in the very early postoperative phase.

scholarly journals Patient-specific instrumentation (PSI) Referencing High Tibial Osteotomy Technological Transfer and Education: protocol for a double-blind, randomised controlled trial (PROTECTED HTO Trial)

BMJ Open ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. e041129
Author(s):  
Lawrence Chun Man Lau ◽  
Elvis Chun Sing Chui ◽  
Jason Chi Ho Fan ◽  
Gene Chi Wai Man ◽  
Yuk Wah Hung ◽  
...  
Keyword(s):  
Randomised Controlled Trial ◽  
Knee Osteoarthritis ◽  
High Tibial Osteotomy ◽  
Controlled Trial ◽  
Patient Specific ◽  
Tibial Osteotomy ◽  
Double Blind ◽  
Patient Specific Instrumentation ◽  
3D Printed ◽  
Randomised Controlled

IntroductionHigh tibial osteotomy (HTO) is a treatment of choice for active adult with knee osteoarthritis. With advancement in CT imaging with three-dimensional (3D) model reconstruction, virtual planning and 3D printing, patient-specific instrumentation (PSI) in form of cutting jigs is employed to improve surgical accuracy and outcome of HTO. The aim of this randomised controlled trial (RCT) is to explore the surgical outcomes of HTO for the treatment of medial compartment knee osteoarthritis with or without a 3D printed patient-specific jig.Methods and analysisA double-blind RCT will be conducted with patients and outcome assessors blinded to treatment allocation. This meant that neither the patients nor the outcome assessors would know the actual treatment allocated during the trial. Thirty-six patients with symptomatic medial compartment knee osteoarthritis fulfilling our inclusion criteria will be invited to participate the study. Participants will be randomly allocated to one of two groups (1:1 ratio): operation with 3D printed patient-specific jig or operation without jig. Measurements will be taken before surgery (baseline) and at postoperatively (6, 12 and 24 months). The primary outcome includes radiological accuracy of osteotomy. Secondary outcomes include a change in knee function from baseline to postoperatively as measured by three questionnaires: Knee Society Scores (Knee Scores and Functional Scores), Oxford Knee Scores and pain visual analogue scale (VAS) score.Ethics and disseminationEthical approval has been obtained from the Joint Chinese University of Hong Kong – New Territories East Cluster Clinical Research Ethics Committee (CREC no. 2019.050), in accordance with the Declaration of Helsinki. The results will be presented at international scientific meetings and through publications in peer-reviewed journals.Trial registration numberNCT04000672; Pre-results.

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