Medial Deviation of a 6° Prosthetic Trochlear Groove After Kinematically Aligned Total Knee Arthroplasty Occurs in Four Types of Coronal Plane Alignment of the Knee (CPAK) and Decreases the Forgotten Joint Score.

Background: The study focused on kinematically aligned total knee arthroplasty (KA TKA). It identified which coronal plane alignment of the knee (CPAK) types are associated with a higher proportion of medial deviation of the 6° prosthetic trochlear groove (PTG) relative to the quadriceps' line of pull and whether medial deviation adversely affected the Forgotten Joint Score (FJS). The research calculated the minimum PTG angle required to prevent medial deviation by at least 2° in all patients.

A new tibial insert design with ball-in-socket medial conformity and posterior cruciate ligament retention has low tibial baseplate migration after unrestricted kinematically aligned total knee arthroplasty: a cohort study using radiostereometric analysis.

Background And Purpose:  In total knee arthroplasty (TKA), an insert with ball-in-socket (BS) medial conformity (MC) and posterior cruciate ligament (PCL) retention restores kinematics closer to native than an insert with intermediate (I) MC. However, high medial conformity might compromise baseplate stability as indicated by maximum total point motion (MTPM). Using the BS MC insert with PCL retention, we aimed to determine whether (i) the baseplate is stable as indicated by mean MTPM < 0.

Unbiased Method to Determine Articular Cartilage Thickness Using a Three-Dimensional Model Derived from Laser Scanning: Demonstration on the Distal Femur.

Measuring articular cartilage thickness from 3D models developed from laser scans has the potential to offer high accuracy. However, this potential has not been fulfilled, since generating these models requires that the cartilage be removed, and previous methods of removal have led to systematic errors (i.e.

An Insert Goniometer Can Help Select the Optimal Insert Thickness When Performing Kinematically Aligned Total Knee Arthroplasty with a Medial 1:1 Ball-in-Socket and Lateral Flat Surface Insert and Posterior Cruciate Ligament Retention.

Current surgical practices in total knee arthroplasty (TKA) have advanced and include significant changes and improvements in alignment philosophies, femorotibial implant conformities, and ligament management to replicate in vivo knee kinematics. While corrective measures have emphasized sagittal plane alignment to restore normal flexion-extension (F-E) motion and coronal plane ligament balance, internal-external (I-E) rotation kinematics in the axial plane have been largely neglected. Recent in vivo evidence indicates that the combination of factors necessary to closely restore native tibial rotation as the knee flexes and extends is kinematic alignment (KA), which resurfaces the patient's pre-arthritic knee without releasing ligaments, an insert with medial 1:1 ball-in-socket conformity and a lateral flat surface, and posterior cruciate ligament (PCL) retention.

A bone graft from the tibial resection or patella that rectified a tibial over-resection reliably healed and improved clinical outcome scores: A retrospective study of kinematically aligned TKA.

Purpose: During kinematically aligned (KA) total knee arthroplasty (TKA), the surgeon may need to rectify an over-resection of the medial, lateral or posterior tibia. This study tested the hypothesis that a bone graft taken from the tibial resection or patella and impacted beneath a tibial baseplate would heal, regardless of whether the tibial component and knee were in outlier ranges according to mechanical alignment (MA) criteria. The study also tested the hypothesis that the Oxford Knee Score (OKS) and Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) would improve beyond the substantial clinical benefit and that the source and thickness of the bone graft would not influence their improvement.

Critical Examination of Methods to Determine Tibiofemoral Kinematics and Tibial Contact Kinematics Based on Analysis of Fluoroscopic Images.

Goals of knee replacement surgery are to restore function and maximize implant longevity. To determine how well these goals are satisfied, tibial femoral kinematics and tibial contact kinematics are of interest. Tibiofemoral kinematics, which characterize function, is movement between the tibia and femur whereas tibial contact kinematics, which is relevant to implant wear, is movement of the location of contact by the femoral implant on the tibial articular surface.

Analysis of Variation in Sagittal Curvature of the Femoral Condyles.

In designing femoral components, which restore native (i.e., healthy) knee kinematics, the flexion-extension (F-E) axis of the tibiofemoral joint should match that of the native knee.

Guideline for RSA and CT-RSA implant migration measurements: an update of standardizations and recommendations.

Opening remarks: These guidelines are the result of discussions within a diverse group of RSA researchers. They were approved in December 2023 by the board and selected members of the International Radiostereometry Society to update the guidelines by Valstar et al. [1].

Similar Recovery Rate for Patients Aged between 50 and 89 Years That Go Home on the Surgery Day and Self-Administer Their Rehabilitation after Kinematically Aligned Total Knee Arthroplasty.

Background: for kinematic alignment (KA) total knee arthroplasty (TKA), it was unknown whether 'the pace of recovery' at six weeks was different for patients with ages ranging between 50-59, 60-69, 70-79, and 80-89 years who were discharged on the surgery day and self-administered their rehabilitation.

Methods: a single surgeon treated 206 consecutive patients with a KA-designed femoral component and an insert with a medial ball-in-socket, lateral flat articulation, and PCL retention. Each filled out preoperative and six-week Oxford Knee Score (OKS), Knee Society Score (KSS), Knee Function Score (KFS), and Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) questionnaires.

Correcting for asymmetry of the proximal tibial epiphysis is warranted to determine postoperative alignment deviations in kinematic alignment from planned alignment of the tibial component on the native tibia.

Background: In total knee arthroplasty, unrestricted kinematic alignment aims to restore pre-arthritic lower limb alignment and joint lines. Joint line orientations of the contralateral healthy proximal tibia might be used to evaluate accuracy of tibial component alignment post-operatively if asymmetry is minimal. Our objective was to evaluate left-to-right asymmetry of the proximal tibial epiphysis in posterior tibial slope and varus-valgus orientation as related to unrestricted kinematic alignment principles.

Risk of tibial baseplate loosening is low in patients following unrestricted kinematic alignment total knee arthroplasty using a cruciate-retaining medial conforming insert: A study using radiostereometric analysis at 2 years.

Purpose: Assessing the risk of tibial baseplate loosening in patients after unrestricted kinematically aligned (unKA) total knee arthroplasty (TKA) using a medially conforming insert is important because baseplates generally are aligned in varus which has been linked to an increased incidence of aseptic loosening following mechanically aligned TKA. Two limits that indicate long-term stability in patients are a change in maximum total point motion between 1 and 2 years (ΔMTPM) < 0.2 mm and anterior tilt at 2 years < 0.

Significantly better precision with new machine learning versus manual image registration software in processing images from single-plane fluoroscopy to determine tibiofemoral kinematics following total knee replacement.

One common method to determine tibiofemoral kinematics following total knee replacement (TKR) is to capture single-plane fluoroscopic images of a patient activity and determine anterior-posterior (AP) positions of the femoral condyles and internal-external (IE) tibial rotation. Although JointTrack is widely used to analyze such images, precision (i.e.

Differences in Trochlear Morphology of a New Femoral Component Designed for Kinematic Alignment from a Mechanical Alignment Design.

Because kinematic alignment (KA) aligns femoral components in greater valgus and with less external rotation than mechanical alignment (MA), the trochlear groove of an MA design used in KA is medialized, which can lead to complications. Hence, a KA design has emerged. In this study, our primary objective was to quantify differences in trochlear morphology between the KA design and the MA design from which the KA design evolved.

A new tibial insert design with ball-in-socket medial conformity and posterior cruciate ligament retention closely restores native knee tibial rotation after unrestricted kinematic alignment.

Purpose: In total knee arthroplasty (TKA) with posterior cruciate ligament (PCL) retention, the medial and lateral insert conformity that restores in vivo native (i.e., healthy) knee tibial rotation and high function without causing stiffness is unknown.

State of the Art in Radiostereometric Analysis for Tibial Baseplate Migration and Future Research Directions.

Radiostereometric analysis (RSA) measures movement (migration) of a baseplate relative to the underlying tibia after total knee arthroplasty (TKA) and has been used extensively to evaluate safety of new implant designs and/or surgical techniques regarding baseplate loosening. Because RSA is a complex methodology which involves various choices that researchers make, including whether to use marker-based or model-based methods, which migration metric to report, how to relate short-term migrations to long-term risk, and how these choices impact error, the objectives of this review were to: (1) lay out a comprehensive structure illustrating the multiple components/considerations for RSA and their interrelations, (2) review components of the structure using the latest RSA literature, and (3) use the preceding review as a context for identifying future areas of study. The components to be reviewed were structured using the following topics: type of RSA, migration metrics, sources of error, studies/reports of error, stability limits, and studies of error in stability limits.

Better forgotten joint scores when the angle of the prosthetic trochlea is lateral to the quadriceps vector in kinematically aligned total knee arthroplasty.

Purpose: The primary aim was to analyze unrestricted kinematic alignment (unKA) total knee arthroplasty (TKA) and determine the frequency of medial deviation of the prosthetic trochlear angle (PTA) of the femoral component relative to the quadriceps vector (QV) that terminates at the anterior inferior iliac spine (AIIS), and whether patients with medial deviation had a worse Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) relative to those with lateral deviation. The secondary aim was to determine the frequency of medial deviation for mechanical alignment (MA) TKA simulations.

Methods: From a database of a single surgeon, the study extracted de-identified data on 147 patients with a CT scanogram showing the pelvis and AIIS, a limb with an unKA TKA, and a native (i.

Reoperation, Implant Survival, and Clinical Outcome After Kinematically Aligned Total Knee Arthroplasty: A Concise Clinical Follow-Up at 16 Years.

Background: The preceding study reported a 10-year follow-up of 222 kinematically aligned total knee arthroplasties (TKA) performed in 217 patients in 2007. As 35% of tibial components and 8% of limbs were in >3° varus, the present study assessed whether this adversely affected reoperation, implant survival, and function at 16 years.

Methods: We retrospectively reviewed a single surgeon's private practice database to determine the patients who underwent reoperation as well as Forgotten Joint Score and Oxford Knee Score.

A Torn or Reconstructed Anterior Cruciate Ligament Does Not Adversely Affect Clinical Outcome Scores and the Incidence of Reoperation After Unrestricted Kinematically Aligned Total Knee Arthroplasty.

Background: There are no reports as to whether the condition of the anterior cruciate ligament (ACL) adversely affects the 2 to 3 year function and reoperation risk of a kinematically aligned (KA) total knee arthroplasty (TKA) performed with posterior cruciate ligament (PCL) retention and an intermediate medial conforming (MC) insert.

Methods: A single surgeon's prospective database query identified 418 consecutive primary TKAs performed between January 2019 and December 2019. The surgeon recorded the ACL condition in the operative note.

Ball-in-socket medial conformity with posterior cruciate ligament retention neither limits internal tibial rotation and knee flexion nor lowers clinical outcome scores after unrestricted kinematically aligned total knee arthroplasty.

Purpose: For a new tibial insert design with ball-in-socket (B-in-S) medial conformity (MC), posterior cruciate ligament (PCL) retention, and flat lateral articular surface (B-in-S MC + PCL), this study determined whether internal tibial rotation and knee flexion were limited and clinical outcome scores were lower during weight-bearing activities relative to an insert with intermediate (I) (i.e., less than ball-in-socket) medial conformity (I MC + PCL).

Correcting for distal femoral asymmetry is necessary to determine postoperative alignment deviations from planned alignment of the femoral component.

Background: One method for assessing the accuracy of manual, patient-specific, navigational, and robotic-assisted total knee arthroplasty (TKA) instrumentation is to use a post-operative computer tomogram and determine the deviation of the femoral component alignment relative to the planned alignment in the native (i.e. healthy) contralateral distal femoral epiphysis.

Conditions for Use and Implementation of Globally-Aligned Versus Local Baseplate Coordinate Systems When Computing Migration Using Radiostereometric Analysis.

Radiostereometric analysis can be used for computing movement of a tibial baseplate relative to the tibia (termed migration) to determine stability of fixation. Quantifying migration in six degrees of freedom requires establishing a coordinate system in which to express the movement. Establishing consistent migration directions among patients and baseplate designs remains challenging.

Caliper-Verified Kinematically Aligned Total Knee Arthroplasty: Rationale, Targets, Accuracy, Balancing, Implant Survival, and Outcomes.

Peer-reviewed studies published up to May 2022 are used to provide a comprehensive understanding of unrestricted kinematically aligned total knee arthroplasty. The intent is to cultivate the curiosity of those interested in this method of personalized alignment. The rationale of unrestricted kinematic alignment is to set the femoral and tibial components coincident with the patient's prearthritic joint lines, restore the femoral and tibial phenotypes, and coalign the three kinematic axes of the components with those of the knee.