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Accuracy of biplane x-ray imaging combined with model-based tracking for measuring in-vivo patellofemoral joint motion.

Bey MJ, Kline SK, Tashman S, Zauel R - J Orthop Surg Res (2008)

Bottom Line: The model-based tracking technique results were in excellent agreement with the RSA technique.This model-based tracking technique is a non-invasive method for accurately measuring dynamic PF joint motion under in-vivo conditions.The technique is sufficiently accurate in measuring clinically relevant changes in PF joint motion following conservative or surgical treatment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Henry Ford Health Systems, Department of Orthopaedics, Bone and Joint Center, E&R 2015, 2799 W Grand Blvd, Detroit, MI 48202, USA. bey@bjc.hfh.edu

ABSTRACT

Background: Accurately measuring in-vivo motion of the knee's patellofemoral (PF) joint is challenging. Conventional measurement techniques have largely been unable to accurately measure three-dimensional, in-vivo motion of the patella during dynamic activities. The purpose of this study was to assess the accuracy of a new model-based technique for measuring PF joint motion.

Methods: To assess the accuracy of this technique, we implanted tantalum beads into the femur and patella of three cadaveric knee specimens and then recorded dynamic biplane radiographic images while manually flexing and extending the specimen. The position of the femur and patella were measured from the biplane images using both the model-based tracking system and a validated dynamic radiostereometric analysis (RSA) technique. Model-based tracking was compared to dynamic RSA by computing measures of bias, precision, and overall dynamic accuracy of four clinically-relevant kinematic parameters (patellar shift, flexion, tilt, and rotation).

Results: The model-based tracking technique results were in excellent agreement with the RSA technique. Overall dynamic accuracy indicated errors of less than 0.395 mm for patellar shift, 0.875 degrees for flexion, 0.863 degrees for tilt, and 0.877 degrees for rotation.

Conclusion: This model-based tracking technique is a non-invasive method for accurately measuring dynamic PF joint motion under in-vivo conditions. The technique is sufficiently accurate in measuring clinically relevant changes in PF joint motion following conservative or surgical treatment.

No MeSH data available.


The model-based tracking technique relies upon: A) internal information such as subtle differences in bone density and/or B) the presence of bone edges in an x-ray image that do not necessarily contribute to the outline of a particular bone in all joint positions.
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Figure 3: The model-based tracking technique relies upon: A) internal information such as subtle differences in bone density and/or B) the presence of bone edges in an x-ray image that do not necessarily contribute to the outline of a particular bone in all joint positions.

Mentions: We believe that it is necessary to conduct a validation study for each anatomical joint to which we intend to apply the model-based tracking technique. Stated another way, we believe that it would be highly inappropriate to validate this technique for, say, the glenohumeral joint and then assume that the accuracy levels obtained in that particular validation study could be assumed to be the same for every other anatomical joint. This belief is based on the fact that the factors influencing the accuracy of the model-based technique are not the same for all anatomical joints, and that the conditions for conducting validation studies should as much as possible resemble actual in-vivo testing conditions. The specific factors influencing the accuracy of this technique include the 3D shape of a particular bone, the amount of "internal" bone information (i.e., variability in bone density and/or the presence of bone edges that appear in an x-ray image but do not necessarily contribute to the outline of a particular bone in all joint positions, Figure 3), the presence of surrounding soft tissues, overlap from surrounding bones, the magnitude of joint motion, and the velocity of joint motion. Although we have not yet assessed the relative influence of each of these factors to model-based tracking accuracy, this list of factors comes from first-hand experience with the technique.


Accuracy of biplane x-ray imaging combined with model-based tracking for measuring in-vivo patellofemoral joint motion.

Bey MJ, Kline SK, Tashman S, Zauel R - J Orthop Surg Res (2008)

The model-based tracking technique relies upon: A) internal information such as subtle differences in bone density and/or B) the presence of bone edges in an x-ray image that do not necessarily contribute to the outline of a particular bone in all joint positions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2538511&req=5

Figure 3: The model-based tracking technique relies upon: A) internal information such as subtle differences in bone density and/or B) the presence of bone edges in an x-ray image that do not necessarily contribute to the outline of a particular bone in all joint positions.
Mentions: We believe that it is necessary to conduct a validation study for each anatomical joint to which we intend to apply the model-based tracking technique. Stated another way, we believe that it would be highly inappropriate to validate this technique for, say, the glenohumeral joint and then assume that the accuracy levels obtained in that particular validation study could be assumed to be the same for every other anatomical joint. This belief is based on the fact that the factors influencing the accuracy of the model-based technique are not the same for all anatomical joints, and that the conditions for conducting validation studies should as much as possible resemble actual in-vivo testing conditions. The specific factors influencing the accuracy of this technique include the 3D shape of a particular bone, the amount of "internal" bone information (i.e., variability in bone density and/or the presence of bone edges that appear in an x-ray image but do not necessarily contribute to the outline of a particular bone in all joint positions, Figure 3), the presence of surrounding soft tissues, overlap from surrounding bones, the magnitude of joint motion, and the velocity of joint motion. Although we have not yet assessed the relative influence of each of these factors to model-based tracking accuracy, this list of factors comes from first-hand experience with the technique.

Bottom Line: The model-based tracking technique results were in excellent agreement with the RSA technique.This model-based tracking technique is a non-invasive method for accurately measuring dynamic PF joint motion under in-vivo conditions.The technique is sufficiently accurate in measuring clinically relevant changes in PF joint motion following conservative or surgical treatment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Henry Ford Health Systems, Department of Orthopaedics, Bone and Joint Center, E&R 2015, 2799 W Grand Blvd, Detroit, MI 48202, USA. bey@bjc.hfh.edu

ABSTRACT

Background: Accurately measuring in-vivo motion of the knee's patellofemoral (PF) joint is challenging. Conventional measurement techniques have largely been unable to accurately measure three-dimensional, in-vivo motion of the patella during dynamic activities. The purpose of this study was to assess the accuracy of a new model-based technique for measuring PF joint motion.

Methods: To assess the accuracy of this technique, we implanted tantalum beads into the femur and patella of three cadaveric knee specimens and then recorded dynamic biplane radiographic images while manually flexing and extending the specimen. The position of the femur and patella were measured from the biplane images using both the model-based tracking system and a validated dynamic radiostereometric analysis (RSA) technique. Model-based tracking was compared to dynamic RSA by computing measures of bias, precision, and overall dynamic accuracy of four clinically-relevant kinematic parameters (patellar shift, flexion, tilt, and rotation).

Results: The model-based tracking technique results were in excellent agreement with the RSA technique. Overall dynamic accuracy indicated errors of less than 0.395 mm for patellar shift, 0.875 degrees for flexion, 0.863 degrees for tilt, and 0.877 degrees for rotation.

Conclusion: This model-based tracking technique is a non-invasive method for accurately measuring dynamic PF joint motion under in-vivo conditions. The technique is sufficiently accurate in measuring clinically relevant changes in PF joint motion following conservative or surgical treatment.

No MeSH data available.