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Kinematic analysis of a posterior-stabilized knee prosthesis.

Zhao ZX, Wen L, Qu TB, Hou LL, Xiang D, Bin J - Chin. Med. J. (2015)

Bottom Line: Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments.The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0-135° flexion.Both the output data trends and the measured values derived from the normal knee's kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopedics, Beijing Chao Yang Hospital, Capital Medical University, Beijing 100020, China.

ABSTRACT

Background: The goal of total knee arthroplasty (TKA) is to restore knee kinematics. Knee prosthesis design plays a very important role in successful restoration. Here, kinematics models of normal and prosthetic knees were created and validated using previously published data.

Methods: Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. The data from the three-dimensional models of the normal knee joint and a posterior-stabilized (PS) knee prosthesis were imported into finite element analysis software to create the final kinematic model of the TKA prosthesis, which was then validated by comparison with a previous study. The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0-135° flexion.

Results: Both the output data trends and the measured values derived from the normal knee's kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses. The PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee and has insufficient, or insufficiently aggressive, "rollback" compared with the lateral femur of the normal knee. In addition, a certain degree of reverse rotation occurs during flexion of the PS knee prosthesis.

Conclusions: There were still several differences between the kinematics of the PS knee prosthesis and a normal knee, suggesting room for improving the design of the PS knee prosthesis. The abnormal kinematics during early flexion shows that the design of the articular surface played a vital role in improving the kinematics of the PS knee prosthesis.

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(a) The comparison on the displacement of medial femur between normal knee and posterior-stabilized knee prosthesis. (b) The comparison on the displacement of lateral femur between normal knee and posterior-stabilized knee prosthesis. (c) The comparison on the internal rotation angle of the tibia between normal knee and posterior-stabilized knee prosthesis.
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Figure 4: (a) The comparison on the displacement of medial femur between normal knee and posterior-stabilized knee prosthesis. (b) The comparison on the displacement of lateral femur between normal knee and posterior-stabilized knee prosthesis. (c) The comparison on the internal rotation angle of the tibia between normal knee and posterior-stabilized knee prosthesis.

Mentions: Analysis was performed on the kinematic characteristics of the PS knee prosthesis based on the kinematics model of the TKA prosthesis and three other parameters: The displacement of the medial femur, the displacement of the lateral femur, and the internal rotation angle of the tibia. The kinematics characteristics of the normal knee and the PS knee prosthesis are compared below. The maximum displacement of the medial femur after implantation of the PS knee prosthesis was about 5.1 mm compared with 3.1 mm in a normal knee. This result indicates that the PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee [Figure 4a]. The backward displacement of the lateral femur with the PS knee prosthesis was nearly 0 mm for flexion angles <90°, and the maximum backward displacement was about 10 mm for flexion angles more than 90°. The lateral femur of the normal knee experiences a continuous “rollback” movement, and the maximum backward displacement is about 21.1 mm. This finding indicates that the PS knee prosthesis has an insufficient, or insufficiently aggressive, “rollback” compared with the lateral femur of the normal knee [Figure 4b]. The internal rotation angle of the tibia in the PS knee prosthesis was <7° for flexion angles <105°. There was mild reverse rotation (about 1°) when the knee flexion angle was between 60° and 105°. This reverse rotation angle increased to 20.6° when the flexion angle was over 105°, while the internal rotation angle of the tibia in normal knees continuously increases until 22.3°. This finding indicates that the tibia, after implantation of a PS knee prosthesis, has insufficient internal rotation compared with the tibia in normal knees, and that there is a certain degree of reverse rotation during flexion [Figure 4c].


Kinematic analysis of a posterior-stabilized knee prosthesis.

Zhao ZX, Wen L, Qu TB, Hou LL, Xiang D, Bin J - Chin. Med. J. (2015)

(a) The comparison on the displacement of medial femur between normal knee and posterior-stabilized knee prosthesis. (b) The comparison on the displacement of lateral femur between normal knee and posterior-stabilized knee prosthesis. (c) The comparison on the internal rotation angle of the tibia between normal knee and posterior-stabilized knee prosthesis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837841&req=5

Figure 4: (a) The comparison on the displacement of medial femur between normal knee and posterior-stabilized knee prosthesis. (b) The comparison on the displacement of lateral femur between normal knee and posterior-stabilized knee prosthesis. (c) The comparison on the internal rotation angle of the tibia between normal knee and posterior-stabilized knee prosthesis.
Mentions: Analysis was performed on the kinematic characteristics of the PS knee prosthesis based on the kinematics model of the TKA prosthesis and three other parameters: The displacement of the medial femur, the displacement of the lateral femur, and the internal rotation angle of the tibia. The kinematics characteristics of the normal knee and the PS knee prosthesis are compared below. The maximum displacement of the medial femur after implantation of the PS knee prosthesis was about 5.1 mm compared with 3.1 mm in a normal knee. This result indicates that the PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee [Figure 4a]. The backward displacement of the lateral femur with the PS knee prosthesis was nearly 0 mm for flexion angles <90°, and the maximum backward displacement was about 10 mm for flexion angles more than 90°. The lateral femur of the normal knee experiences a continuous “rollback” movement, and the maximum backward displacement is about 21.1 mm. This finding indicates that the PS knee prosthesis has an insufficient, or insufficiently aggressive, “rollback” compared with the lateral femur of the normal knee [Figure 4b]. The internal rotation angle of the tibia in the PS knee prosthesis was <7° for flexion angles <105°. There was mild reverse rotation (about 1°) when the knee flexion angle was between 60° and 105°. This reverse rotation angle increased to 20.6° when the flexion angle was over 105°, while the internal rotation angle of the tibia in normal knees continuously increases until 22.3°. This finding indicates that the tibia, after implantation of a PS knee prosthesis, has insufficient internal rotation compared with the tibia in normal knees, and that there is a certain degree of reverse rotation during flexion [Figure 4c].

Bottom Line: Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments.The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0-135° flexion.Both the output data trends and the measured values derived from the normal knee's kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopedics, Beijing Chao Yang Hospital, Capital Medical University, Beijing 100020, China.

ABSTRACT

Background: The goal of total knee arthroplasty (TKA) is to restore knee kinematics. Knee prosthesis design plays a very important role in successful restoration. Here, kinematics models of normal and prosthetic knees were created and validated using previously published data.

Methods: Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. The data from the three-dimensional models of the normal knee joint and a posterior-stabilized (PS) knee prosthesis were imported into finite element analysis software to create the final kinematic model of the TKA prosthesis, which was then validated by comparison with a previous study. The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0-135° flexion.

Results: Both the output data trends and the measured values derived from the normal knee's kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses. The PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee and has insufficient, or insufficiently aggressive, "rollback" compared with the lateral femur of the normal knee. In addition, a certain degree of reverse rotation occurs during flexion of the PS knee prosthesis.

Conclusions: There were still several differences between the kinematics of the PS knee prosthesis and a normal knee, suggesting room for improving the design of the PS knee prosthesis. The abnormal kinematics during early flexion shows that the design of the articular surface played a vital role in improving the kinematics of the PS knee prosthesis.

Show MeSH
Related in: MedlinePlus