Mechanical alignment is a method used to achieve a neutral hip-knee-ankle axis. Kinematic alignment, on the other hand, is an alternative technique in Total Knee Arthroplasty (TKA) that aims to preserve the natural kinematic axis and ligament balance of the patient's knee. The purpose of this study is to biomechanically compare the effect of mechanical and kinematic alignment on a knee after TKA. In-silico models are often used to study knee kinematics in healthy or pathological conditions. An anatomical model of the native knee was created by segmenting CT images of the femur, patella and tibia. Additionally, the model incorporated the medial collateral ligament (MCL), lateral collateral ligament (LCL), medial patellofemoral ligament (MPFL), lateral retinaculum, and patellar tendon to achieve a comprehensive joint representation. Ligaments of knee joint were modelled using two-dimensional shell elements. Two three-dimensional knee models based on the native knee derived from segmentation were implemented to simulate the two different surgical techniques, mechanical alignment and kinematic alignment. To evaluate the performance of the models, a squat movement from 0 to 120 degrees was simulated. The study focused on the patellofemoral and tibiofemoral joints, analysing the kinematics of the two joints as well as the contact areas and contact forces in the two alignment approaches. In conclusion, this study highlighted the potential benefits of achieving a joint line restoration closely aligned with its natural position, which may lead to superior clinical outcomes in kinematically aligned TKA. However, the persistence of patellofemoral complications remains a concern, especially when using conventional implants designed for mechanical alignment in the kinematic alignment approach.
L'allineamento meccanico è un metodo utilizzato per ottenere un asse anca-ginocchio-caviglia neutro. L'allineamento cinematico, invece, è una tecnica alternativa nell'artroplastica totale del ginocchio (TKA) che mira a preservare l'asse cinematico naturale e l'equilibrio legamentoso del ginocchio del paziente. Lo scopo di questo studio è quello di confrontare biomeccanicamente l'effetto dell'allineamento meccanico e cinematico su un ginocchio dopo la TKA. I modelli in-silico sono spesso utilizzati per studiare la cinematica del ginocchio in condizioni sane o patologiche. È stato creato un modello anatomico del ginocchio nativo segmentando le immagini TC di femore, rotula e tibia. Inoltre, sono stati inclusi nel modello il legamento collaterale mediale (MCL), il legamento collaterale laterale (LCL), il legamento patellofemorale mediale (MPFL), il retinacolo laterale e il tendine rotuleo per ottenere una rappresentazione completa dell'articolazione. I legamenti dell'articolazione del ginocchio sono stati modellati utilizzando elementi shell bidimensionali. Sono stati implementati due modelli di ginocchio tridimensionali basati sul ginocchio nativo derivato dalla segmentazione per simulare le due diverse tecniche chirurgiche, l'allineamento meccanico e l'allineamento cinematico. Per valutare le prestazioni dei modelli, è stato simulato un movimento di squat da 0 a 120 gradi. Lo studio si è concentrato sulle articolazioni patellofemorale e tibiofemorale, analizzando la cinematica delle due articolazioni oltre alle aree di contatto e le forze di contatto nei due approcci di allineamento. In conclusione, questo studio evidenzia i potenziali vantaggi di ripristinare la joint line, allineandola alla sua posizione naturale, che può portare a risultati clinici superiori nella TKA ad allineamento cinematico. Tuttavia, la persistenza di complicazioni patellofemorali rimane un’incertezza, soprattutto quando si utilizzano impianti convenzionali progettati per l'allineamento meccanico applicati per mezzo dell'approccio di allineamento cinematico.
Mechanical vs Kinematic alignment in Total Knee Arthroplasty: an in-silico biomechanical analysis
CARPANESE, FILIPPO
2022/2023
Abstract
Mechanical alignment is a method used to achieve a neutral hip-knee-ankle axis. Kinematic alignment, on the other hand, is an alternative technique in Total Knee Arthroplasty (TKA) that aims to preserve the natural kinematic axis and ligament balance of the patient's knee. The purpose of this study is to biomechanically compare the effect of mechanical and kinematic alignment on a knee after TKA. In-silico models are often used to study knee kinematics in healthy or pathological conditions. An anatomical model of the native knee was created by segmenting CT images of the femur, patella and tibia. Additionally, the model incorporated the medial collateral ligament (MCL), lateral collateral ligament (LCL), medial patellofemoral ligament (MPFL), lateral retinaculum, and patellar tendon to achieve a comprehensive joint representation. Ligaments of knee joint were modelled using two-dimensional shell elements. Two three-dimensional knee models based on the native knee derived from segmentation were implemented to simulate the two different surgical techniques, mechanical alignment and kinematic alignment. To evaluate the performance of the models, a squat movement from 0 to 120 degrees was simulated. The study focused on the patellofemoral and tibiofemoral joints, analysing the kinematics of the two joints as well as the contact areas and contact forces in the two alignment approaches. In conclusion, this study highlighted the potential benefits of achieving a joint line restoration closely aligned with its natural position, which may lead to superior clinical outcomes in kinematically aligned TKA. However, the persistence of patellofemoral complications remains a concern, especially when using conventional implants designed for mechanical alignment in the kinematic alignment approach.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/55471