Post-cam mechanics and tibiofemoral kinematics: a dynamic in vitro analysis of eight posterior-stabilized total knee designs

Posterior-stabilized (PS) total knee arthroplasty (TKA) designs were introduced to compensate for the resected or deficient posterior cruciate ligament and to avoid paradoxical anterior sliding of the femur. Knee joint stability may differ among patients and, therefore, orthopaedic companies developed several solutions to compensate for these differences. In particular, conventional PS designs are used for conventional TKA and semi-constrained PS designs are mainly applied in revision surgery or in conventional surgery when there is a compromised soft tissue envelope. However, despite good functional long-term results, a better understanding of forces acting on the post of the polyethylene insert is needed to find an eventual correlation with the risk of post-cam failure or loosening of the tibial baseplate for the two PS solutions. To the authors' best knowledge, no literature data is currently available to compare the two solutions. In this paper, a validated numerical model was developed to analyse and compare the posterior of the post-cam mechanism of the same TKA design with conventional and semi-constrained inserts during several motor tasks. For each solution, different motor tasks show different values of maximum post-cam force. Comparing the two solutions, a general slightly higher force (range between 3 and 5%) is observed in the semi-constrained solution. The results concerning the conventional solution are in agreement with the literature. After this analysis, we can report that a semi-constrained design shows only slightly higher posterior post-cam contact force, and thus would not be expected to significantly increase the risk of failure of the post-cam mechanism, as compared to a conventional PS design.

show abstract

“…The initial contact angle was 71°flexion. The maximum contact force was 780 N, for the maximum flexion (Figure 4) (Arnout et al 2014).…”

Section: Resultsmentioning

confidence: 94%

Biomechanical analysis of the post-cam mechanism in a TKA: comparison between conventional and semi-constrained insert designs

Pianigiani

Scheys²,

Labey³

et al. 2015

International Biomechanics

View full text Add to dashboard Cite

show abstract

“…Alternatively, the use of a suture-glue combination has been reported [4]. For testing with a knee prosthesis, a common practice is to glue the sensor onto the patella or tibial tray [32], or fixed by the use of double sided tape [2,33]. To minimize shear forces acting on the sensor, a protective Teflon film of 0,1mm is often applied [4, 17-19, 21, 22, 28, 29, 33].…”

Section: Mounting Techniquesmentioning

confidence: 99%

“…Little research has been done to investigate the influence of the mounting method of the sensor on the accuracy of the measurements but several researchers have questioned this [33]. Only the influence of cementing the sensor has been investigated.…”

Section: 3mentioning

confidence: 99%

Use of Tekscan pressure sensors for measuring contact pressures in the human knee joint

Herregodts

Baets

Victor

et al. 2015

SCAD

View full text Add to dashboard Cite

Abstract:The Tekscan pressure sensor is a common instrument to quantify in vitro tibiofemoral and patellofemoral contact pressures, which helps to understand the impact of surgical intervention such as total knee arthroplasty (TKA). As a result of the non-linear behavior of the sensor, the conditioning, normalization and calibration of the sensor are critical to achieve correct measurements. In this paper, a literature review is presented that provides insight in the correct use of these sensors, resulting in optimal accuracy. To guarantee the repeatability of the measurements, a secure and correct fixation of the sensor in the joint is required. Using the sensor for intra-articular measurements induces several unintended effects, which potentially lower the accuracy of the measurement. First, the uneven surface can result in wrinkling and destruction of the sensor, in turn leading to measurement results that can be corrupted. Second, the presence of shear forces on the sensor can lead to wear of the sensor and reduction in sensitivity with loss of accuracy as a result. Also the fixation method can worsen the accuracy. In literature, a deterioration of the accuracy from 3% under optimal conditions to errors of more than 50% are reported as a result of the aforementioned effects.

show abstract

“…Nowadays, dynamic knee rigs are also used in the assessment of surgical techniques by looking into the kinematics of the knee joint (Arnout et al, 2015). Based on these observations, the orthopedic researcher investigates the effect of the surgical technique on the postoperative stability of the knee joint for different types of knee implants.…”

Section: Introductionmentioning

confidence: 99%

A Data-driven Gain Adaptation Mechanism for Flexible Usability in the UGent Knee Rig

et al. 2017

View full text Add to dashboard Cite

This paper presents a data-driven gain adaptation mechanism in order to make the usability of the UGent Knee Rig (UGKR) more flexible. The design of the UGKR is unique as it is characterized by a movable ankle joint contrary to traditional dynamic knee rigs which are used to investigate knee kinematics and surgical techniques. This feature allows the UGKR to perform both bicycle motions and squat motions while applying a quadriceps force and hamstring forces. The control of the UGKR is a model-based control strategy which requires time-consuming system identification for each new knee specimen. A data-driven gain adaptation mechanism is developed reducing the necessary time for identification creating a flexible usability. Two adaptation mechanisms are implemented and tested on both a mechanical hinge and a cadaver knee: a rectangular sequence and a polar sequence. The results from squat and bicycle tests indicate that rectangular sequence provides good performance for the rigid mechanical hinge, however, it fails for the elastic cadaver knee during full extension. It is shown that the polar sequence results in good performance for the cadaver knee compared to the rectangular mechanism.

show abstract

Post-cam mechanics and tibiofemoral kinematics: a dynamic in vitro analysis of eight posterior-stabilized total knee designs

Cited by 53 publications

References 34 publications

Biomechanical analysis of the post-cam mechanism in a TKA: comparison between conventional and semi-constrained insert designs

Biomechanical analysis of the post-cam mechanism in a TKA: comparison between conventional and semi-constrained insert designs

Use of Tekscan pressure sensors for measuring contact pressures in the human knee joint

A Data-driven Gain Adaptation Mechanism for Flexible Usability in the UGent Knee Rig

Contact Info

Product

Resources

About