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Estimating 3D knee joint centre without medial condyle marker & functional method

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  • Estimating 3D knee joint centre without medial condyle marker & functional method

    Hi Biomechanics geeks,

    I am looking for a scientific method to estimate the knee joint centre that does not require the medial condyle marker or an extra trial (functional methods).
    The marker set for the lower limbs is the following (see attached file. Note: KneeOut marker is the marker placed on the lateral condyle of the femur. The ones on the thigh and femur are placed more "randomly" on the anterior part of the segments).
    We are calculating all the joints based on one frame during a static trial.
    Right now, I am building a coordinate system. The primary axis is an anterior axis based on the foot orientation using the HeelBack and Forefoot2 markers. The second axis is a pure vertical axis (0, 0, 1) assuming Z is the vertical component. The origin of this coordinate system is placed at the KneeOut marker. I then applied an offset on the medial axis to place the knee joint centre based on the length of the shin (measured between KneeOut and AnkleOut)

    My method is very empirical and would like to find a scientific method if it exists.
    Do you have papers about methods that can fit my requirements?

    Thank you very much

    Vincent
    Attached Files

  • #2
    Re: Estimating 3D knee joint centre without medial condyle marker & functional method

    Vincent

    Had a similar problem years ago when I had four camera on one side only of the test area. Had to record two static trials (left and right) and similarly in walking trials where right and left were collected alternatively. To record medial knee and ankle I had two light-weight wands with two reflective markers at each end and an identical non-reflective marker in the middle. The center non-reflective marker was placed as usual on the bony landmark in the static trial and its position calculated from the two visible end points. Adds a few extra steps to the procedure but workable for a quick fix.

    Allan

    Comment


    • #3
      Re: Estimating 3D knee joint centre without medial condyle marker & functional method

      This paper describes a method:


      The paper is about parameter estimation of the system based on the redundant kinematic information provided when you have more markers than strictly necessary to drive the system, which is almost always the case. If you consider the knee joint centre as a parameter, then the method will identify it.

      The method is an integral part of the algorithms for mocap processing in the AnyBody Modeling System.

      Best regards,
      John

      Comment


      • #4
        Re: Estimating 3D knee joint centre without medial condyle marker & functional method

        Originally posted by jrasmussen56 View Post
        This paper describes a method:


        The paper is about parameter estimation of the system based on the redundant kinematic information provided when you have more markers than strictly necessary to drive the system, which is almost always the case. If you consider the knee joint centre as a parameter, then the method will identify it.

        The method is an integral part of the algorithms for mocap processing in the AnyBody Modeling System.

        Best regards,
        John
        Hi John,

        Unfortunately it seems like this method needs motion to calculate the knee joint centre. It will never work with a static measurement as input, am i right?
        This is not possible in my case to change the static trial to one with motion since the workflow only uses a static measurement before the person is gonna run and walk afterwards and get real-time feedback at the same time.

        Thank you anyway

        Comment


        • #5
          Re: Estimating 3D knee joint centre without medial condyle marker & functional method

          Originally posted by Allan Carman View Post
          Vincent

          Had a similar problem years ago when I had four camera on one side only of the test area. Had to record two static trials (left and right) and similarly in walking trials where right and left were collected alternatively. To record medial knee and ankle I had two light-weight wands with two reflective markers at each end and an identical non-reflective marker in the middle. The center non-reflective marker was placed as usual on the bony landmark in the static trial and its position calculated from the two visible end points. Adds a few extra steps to the procedure but workable for a quick fix.

          Allan
          Hi Allan,

          Sounds like you really work hard and use all your creativity to find a solution to your problem.
          I am glad it worked for you.
          Unfortunately, this will require a change in my workflow that I cannot afford.
          It seems to me that having medial knee markers only for the static trial would be the best compromise.
          Anyway, thank you very much for your advice.

          Vincent

          Comment


          • #6
            Re: Estimating 3D knee joint centre without medial condyle marker & functional method

            Dear Dr. Fohanno,

            Vicon Motion Systems uses a model of markers and joint center calculations (Helen Hayes and "Offset angles" - Plugin Gait - to the orientation of local coordinate systems of each segment: the pelvis, thigh, shank and foot) that do not employ the medial knee marker to calculate the knee joint center. Some information in the link below under the items: Motion Capture Systems\Vicon Motion Systems


            The image in your email is similar to the improved biomechanical model that minimizes the soft tissue artifact in the thigh by positioning a marker on the patella:
            "Use of a patella marker to improve tracking of dynamic hip rotation range of motion"
            Wren T A, Do K P, Hara R, Rethlefsen S A
            Gait Posture. 2008 Apr;27(3):530-4. Epub 2007 Aug 20


            I have some applications for calculating the static trial and making corrections of the frontal thigh plane with minimization of the knee valgus/varus amplitude in the gait swing phase - similar to the process proposed by Dr. Baker in:
            "A new approach to determine the hip rotation profile from clinical gait analysis data"
            Richard Baker, Laura Finney, John Orr
            Human Movement Science


            However, calculations to adapt the "Offset angles" in dynamic trials will need to be written.

            I hope this information is helpful.
            Best Regards,

            Comment


            • #7
              Re: Estimating 3D knee joint centre without medial condyle marker & functional method

              Originally posted by vfohanno69 View Post
              Hi John,

              Unfortunately it seems like this method needs motion to calculate the knee joint centre. It will never work with a static measurement as input, am i right?
              This is not possible in my case to change the static trial to one with motion since the workflow only uses a static measurement before the person is gonna run and walk afterwards and get real-time feedback at the same time.

              Thank you anyway
              If you don't have motion, then you don't have a rotational axis. A joint center is just a rotaitonal axis visualized in 2D.

              How the knee rotates depends upon how you use it.

              Comment


              • #8
                Re: Estimating 3D knee joint centre without medial condyle marker & functional method

                Vincent,

                I am curious about how you intend to reconstruct segment locations with this marker set and why you are so restrict in your workflow. As ultimately it will affect your ability to describe segment locations and joint angles.

                In the minimalist marker set you present the sequence of segment reconstruction would appear to be top down (from pelvis to foot). This is not ideal and will propagate the larger errors present in the reconstruction of the thigh axes through to the shank and foot axes. Adversely affecting the validity and reliability of the latter two segments.

                As alluded to by Wagner De Godoy, a crucial part of the 3DMA process is understanding, assessing and minimizing axes misalignment. Without which leads large systematic and random errors in reconstructed axes and consequently large non-linear errors in joint angle data. This is seen in the failing of similar minimalist marker sets; PiG, HH, VCM, T3DG, CAST. The minimization of knee abd/add during walking has been suggested and used in the literature, and gives a significant improvement in validity and reliability of joint angle data. However, the majority of knee abd/add occurs during the swing phase reflecting individual differences (or strategies) in shank/foot int/ext rotation, in either swinging through with an internal, neutral or externally rotated lower leg. Adjusting axes alignment based on knee ab/add profile should therefore concentrate on the stance phase of gait (small and repeatable changes) or alternatively use a squat movement.

                While on axes misalignment, it originates across the whole 3DMA process from 3D marker reconstruction, tracking and labeling of 3D points, placement of markers, subject calibration methods, skin movement artifact (markers placed over muscle or bone) and rigid body methods used including constraints imposed.

                Wagner: If you are trying to place markers to minimize skin movement artifact then I am puzzled as to why you would put a thigh marker on the patella. This will introduce large skin movement artifacts during knee flexion and with minimal markers included in the model will introduce relatively large errors in thigh segment axes?

                Cheers
                Allan

                Comment


                • #9
                  Re: Estimating 3D knee joint centre without medial condyle marker & functional method

                  Originally posted by tmgreiner58 View Post
                  If you don't have motion, then you don't have a rotational axis. A joint center is just a rotaitonal axis visualized in 2D.

                  How the knee rotates depends upon how you use it.
                  Thanks. I guessed it already unfortunately. Just wanted to check. Thanks again

                  Comment


                  • #10
                    Re: Estimating 3D knee joint centre without medial condyle marker & functional method

                    Hi Allan,

                    The idea about using a reduced markerset is to decrease the time-consuming setup time and post-processing time (labelling marker) because it will be not be used for research or by researchers but more by sports coaches who need a simple setup, quick (almost immediate) 3D feedback and cannot spend time labeling or placing markers on the subjects. So this is why we are a bit strict regarding the workflow and marker set.
                    We are aware that the thigh and shank coordinate systems are crucial to get reliable joint angles and this is why I was posting a message to see if we could get a good way to estimate the knee joint centre and joint axis with this reduced marker set.
                    We are aware that the accuracy will not be as good as a with a more detailed marker set but still one can get reliable output, if chosen carefully, from this reduced marker set.

                    Thanks for your comments. It is always very nice to exchange ideas like we are doing now. Love it

                    Vincent

                    Comment


                    • #11
                      Re: Estimating 3D knee joint centre without medial condyle marker & functional method

                      Originally posted by Allan Carman View Post
                      Wagner: If you are trying to place markers to minimize skin movement artifact then I am puzzled as to why you would put a thigh marker on the patella. This will introduce large skin movement artifacts during knee flexion and with minimal markers included in the model will introduce relatively large errors in thigh segment axes?
                      Dear Dr. Carman,

                      Patella marker research was developed by Dr. Tishya Wren with a Vicon system and Plugin Gait (PiG) model - a version of the old VCM. I think that patella marker will be effective only in PiG.
                      The construction of the thigh orientation axes in PiG is preceded by the construction of reference planes such as thigh frontal plane (if KAD is used). A draft about the static trial, with KAD is available in the file: "VCM - Joint Centers.pdf"
                      The patella or thigh marker is used in an "Offset angles" geometric model by PiG, and has STA interference, but its displacement occurs mainly in the sagittal plane of the thigh - perpendicular to the frontal plane described above -, thus, the propagation of errors in the orientation of local coordinate system (thigh) is minimized.

                      Dr. Morgan Sangeux discussed this subject on the ResearchGate website recently, but I couldn't find this reference (maybe in Conventional Gait Model 2 Project).

                      A recent research has added the patella marker to a functional biomechanical model: Kinematically Constrained Joint Parameters (KC Method)
                      ESMAC 2018 - "O 007—Inclusion of a patella marker to improve functional model hip rotation tracking"
                      A. Ries, M. Schwartz
                      Gait & Posture , Volume 65, Supplement 1, September 2018, Pages 13-14
                      DOI.org

                      I apologize if this explanation is confusing.
                      Thank you for your attention.
                      Best Regards,
                      Last edited by Wagner De Godoy; September 23, 2019, 12:21 PM. Reason: website link

                      Comment


                      • #12
                        Re: Estimating 3D knee joint centre without medial condyle marker & functional method

                        Vincent

                        Thank you for clarifying, I see that a full 3D approach may be impractical. Considering that experts are unreliable in marker placement a coach would be even less so. As you said, wanting to get markers on quickly without too much fuss and to get to the results. How about breaking the approach down to a simple quasi-3D analysis and focus on pelvic movement (tilt, drop/hike and rotation) and a few key joint angles (hip flex/ext, hip abd/add, knee flex/ext and ankle flex/ext). I think the remaining non-sagital rotations will be too unreliable given the limitations. Then simplifying markers to both ASIS, both PSIS, lower anterior thigh, head of fibula, lateral ankle, heel and toe (plus the virtual hip joint centers). You might get a reasonable estimation of these key rotations so long as you have good initial estimates of actual hip, knee and ankle angles in the static posture. With a simplified approach this might be achieved by just measuring static knee flexion and hip abduction angles?

                        Some ideas, never tried it.

                        Cheers
                        Allan

                        Comment


                        • #13
                          Re: Estimating 3D knee joint centre without medial condyle marker & functional method

                          Wagner de Godoy

                          I have commented previously on traditional marker set on this forum, not wanting to reiterate but touch on some of those points.

                          The reliability of PiG and VCM with or without the KAD device in normal gait are the most common appearing in the literature. What is apparent across these studies, in addition to the poor reliability, is the large variability in reliability reported. With the KAD still unable to produce either reliable or normal joint angle data. The use of the patella marker to define thigh sagital plane does appear to be less prone to placement errors than medial and lateral knee markers. Whether you use knee markers, KAD, patella markers or pointers you are still subject to systematic and random errors in marker placement and associated errors in axes alignment. These methods (HH, PiG, VCM, T3DG, CAST) at best only provide a first approximation to segment axes alignment with no consistency in reliability or normal gait joint angles reported. Defining segment axes in this way is only the start of the subject calibration procedure with further steps required to refine segment axes in order to produce valid and reliable joint angle data; such as establishing static joint angles and optimization of axes orientation based on knee abd/add during a squat movement or stance in walking. When calculating segment axes during movement trials least squares methods should always be used over direct methods even with three markers per segment. I don’t see how least squares could be use with this minimalist set and the inclusion of a patella marker in movement trials.

                          Overall I see the PiG method as an overly complicated process to achieving unreliable segment axes and joint angle data. However there is merit in including a patella marker in the static trial, along with medial and lateral knee markers to define knee joint center and thigh sagital plane and to improve the first approximation of axes alignment to be used in subsequent axes optimization or refinement procedures.

                          Again my views.

                          Cheers
                          Allan

                          Comment


                          • #14
                            Re: Estimating 3D knee joint centre without medial condyle marker & functional method

                            Allan

                            Thanks for the feedback. Yes. It seems like focusing on angles that can be assess in a reliable way is a good idea.
                            We will do that of course.

                            Thanks for all your time put into this

                            Vincent

                            Comment


                            • #15
                              Re: Estimating 3D knee joint centre without medial condyle marker & functional method

                              You might want to look at the original paper from 1990, "Measurement of Lower Extremity Kinematics During Level Walking" by Kadaba, Ramakrishnan, Wootten.

                              Comment

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