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--- visual3d:documentation:modeling:marker_sets:pig_ll_original [2024/06/18 13:28] – sgranger
+++ visual3d:documentation:modeling:marker_sets:pig_ll_original [2024/07/17 15:45] (current) – created sgranger
@@ Line 1: / Line 1: @@
+====== PiG LL Original ======
 \\
 **N.B. While every effort has been made to ensure the correct implementation of the Plug-In Gait model in Visual3D, some differences may still persist, most likely caused by the different pose estimations used within Nexus and Visual3D. Please report any errors to support@c-motion.com.**
-===== Introduction =====
+==== Introduction ====
 The conventional gait model (CGM) has many variations and can go by many names: Helen Hayes, Vicon Clinical Manager, Newington, and Cleveland Clinic to name a few. We highly recommend reading the [[Visual3D:Tutorials:Modeling:Building_a_Conventional_Gait_Model|Tutorial: Building a Conventional Gait Model]] prior to going through this tutorial.
@@ Line 10: / Line 12: @@
 In this tutorial, we describe this implementation of [[http://www.vicon.com%7C|Vicon's]] Plug-In Gait using Visual3D.
-===== Pose Estimation =====
+==== Pose Estimation ====
 Plug-In Gait uses a Direct (Non-Optimal) Pose Estimation for computing the position and orientation of each segment based on a set of 3 tracking markers.
@@ Line 18: / Line 20: @@
 The results of the implementation of the Plug-In Gait model in Visual3D will differ slightly from the Vicon PIG implementation, but the differences are sufficiently modest that there are no clinically significant differences.
-===== Conventional Gait Model Decisions =====
+==== Conventional Gait Model Decisions ====
 Since there are variations of the conventional gait model, decisions must be made prior to marker placement and data collection. The diagram below lays out some of the decisions based on body segment. This is not comprehensive since many variations exist. The following sections describe the conventional gait model marker placement locations and challenges based on these options.
-[[index.php?title=Special:Upload&wpDestFile=Conventional_gait_model_decisions1.png|File:Conventional gait model decisions1.png]]
+{{:Conventional_gait_model_decisions1.png}}
 In the case of the Plug-In Gait, the decisions have already been made for option 2(c), 4(b) and 5(b). Using Visual3D, it is possible to opt for different model decisions if needed or relevant. This would however not be consistent with the Plug-In Gait's implementation per se.
-===== Anthropometric measures necessary for the Conventional Gait Model =====
+==== Anthropometric measures necessary for the Conventional Gait Model ====
 These lists describe the anthropometric measurements that are needed for the Plug-In Gait variations of the Clinical Gait Model. These are the anthropometric measurements also required in //Workstation// and //Nexus//. Some measurements are clinically measured while others are calculated from the 3D markers or a regression equation. If the no clinical measurements are entered, then calculated value is used.
@@ Line 45: / Line 47: @@
   * ASIS to greater trochanter distance (Calculated from a regression equation: 0.1288*Leg Length-0.04856)
-==== Segment Coordinate Systems ====
+=== Segment Coordinate Systems ===
 The definitions of the segment coordinate systems are based on anatomical orientations and are consistent with many other versions of the conventional gait model.
-===== Marker Placement =====
+==== Marker Placement ====
 Appropriate marker placement for any model is critical. The motion system only measures the center of the marker so when placing markers on the subject, use the center of the marker as your guide and not the attached bases or wands. It is also good practice to use eyeliner pencil or pen to mark on the subject the locations of the markers. If a marker is knocked off or falls, it can easily be placed in the same location. But, one has to be very careful about replacing markers. When Segment Optimization or Global Optimization pose estimation algorithms are used, the missing marker should be replaced, then the standing trial should be collected again; simply replacing the marker is not usually sufficient.
-==== Marker Color Convention ====
+=== Marker Color Convention ===
 The different colored circles relate to the different roles of the markers.
@@ Line 59: / Line 61: @@
 **Red Markers** are used for both the segment definition and for tracking
 **Black markers** are virtual markers used for both the segment definition and for tracking
-==== Pelvis Markers ====
+=== Pelvis Markers ===
 The Plug-In Gait pelvis has two marker set variations: a three-marker marker set and a four-marker marker set. In Visual3D, both marker sets can be used with the [[Visual3D:Documentation:Modeling:Segments:Coda_Pelvis|Coda Pelvis]] (described below). When using the four-marker marker set, Plug-In Gait computes the mid-point between LPSI and RPSI, and uses this mid-point Sacrum marker to define and track the pelvis.
@@ Line 67: / Line 69: @@
 The [[Visual3D:Documentation:Modeling:Segments:Pelvis_Overview|Pelvis Overview]] section and the [[Visual3D:Tutorials:Modeling:Building_a_Conventional_Gait_Model#Pelvis_Markers|conventional gait model]] discuss the differences between the two models.
-=== Four Marker Set Pelvis ===
+== Four Marker Set Pelvis ==
-{{PelvisPiG4.png}}
+{{:PelvisPiG4.png}}
 RIAS , LIAS= Right Ilium Anterior Superior (Anterior Superior Iliac Spine)
 RIPS , LIPS= Left Ilium Posterior Superior (Posterior Superior Iliac Spine)
-=== Three Marker Set Pelvis ===
+== Three Marker Set Pelvis ==
-{{PelvisPiG3.png}}
+{{:PelvisPiG3.png}}
 RIAS , LIAS= Right Ilium Anterior Superior (Anterior Superior Iliac Spine)
@@ Line 87: / Line 89: @@
 The origin of the pelvis is at the mid-point of the ASIS markers and perpendicular to the line joining them regardless of the position of the PSIS markers. Since this is the case, medial/lateral position of the PSIS markers is not critical but care should be taken regarding the vertical position.
-=== Placement challenges for obese subjects ===
+== Placement challenges for obese subjects ==
 Placement on obese subjects can be challenging due to excessive tissue. Have the subject stand to palpate the ASIS's since the skin and tissue may be in different locations for the prone and standing position. There are three options for marker placement: move the ASIS markers more lateral or move the ASIS markers anterior or use the pointer to identify a virtual point.
-== Move ASIS markers Laterally ==
+= Move ASIS markers Laterally =
 Move both ASIS markers lateral to the anatomical ASIS in the pelvic plane. Make sure that the lateral displacement is symmetrical between sides. Measure this distance and modify the **Subject Metric Inter-ASIS_distance**.
-== Move ASIS markers Anteriorly ==
+= Move ASIS markers Anteriorly =
 Move both ASIS markers anterior (coming forward directly anterior to the landmarks so that they lie directly over them in the coronal plane of the pelvis) by an equal distance in relation to where they would have been. Measure this distance and add a landmark that specifies the actual location of the ASIS. These ASIS landmarks should be used for defining the segment coordinate system of the pelvis, but the original markers should be used as the tracking markers for the pelvis.
-== Use a Pointer to make ASIS Landmarks ==
+= Use a Pointer to make ASIS Landmarks =
 A [[Visual3D:Documentation:Modeling:Landmarks:Digitizing_Pointer|Digitizing Pointer]] can be used to identify the ASIS markers.
-==== Upper Leg Markers ====
+=== Upper Leg Markers ===
-{{ThighPiG.png}}
+{{:ThighPiG.png}}
 RHJC, LHJC = Hip joint center
@@ Line 115: / Line 117: @@
 There are two variations for the thigh segment. One in which a [[Visual3D:Documentation:Modeling:Segments:Knee_Alignment_Device|Knee Alignment Device]] (KAD) is used, one without a KAD.
-=== Without Knee Alignment Device (KAD) ===
+== Without Knee Alignment Device (KAD) ==
 The upper leg segment can be visualized as a triangle or plane formed by the Hip Joint Center (RIGH_HIP, LEFT_HIP), lateral thigh marker and lateral knee marker. Palpate lateral epicondyles to estimate the knee flexion/extension axis. Place a marker on the right and left Lateral Epicondyles (RKNE, LKNE) to approximate this axis. This should be done in the standing position with the subject passively flexing and extending the joint to confirm placement. **You are looking for a point that is fixed in the thigh and about which the lower leg appears to rotate.** Mark that location with eyeliner pencil or a pen.
@@ Line 121: / Line 123: @@
 When not using a [[Visual3D:Documentation:Modeling:Segments:Knee_Alignment_Device|Knee Alignment Device]] (KAD) the placement of the thigh markers (RTHI, LTHI) or wands (stick on a base with an attached marker) is critical. This marker is used to define the frontal plane of the femur (knee flexion/extension axis location and orientation). The distal 1/3 of the thigh is the best location to decrease movement due to muscle bulk and swing of the hands. The vertical height is not critical but try not place the thigh marker too low on the thigh. The anterior/posterior position of this marker is critical and it is extremely difficult to visualize. Adjust the marker so that it is aligned in the plane that contains the hip and knee joint centers and the knee flexion/extension axis. Position this marker standing and observe knee flexion/extension to confirm.
-=== Using a Knee Alignment Device (KAD) ===
+== Using a Knee Alignment Device (KAD) ==
 As above, the upper leg segment can be visualized as a triangle or plane formed by the Hip Joint Center (RIGHT_HIP, LEFT_HIP), lateral thigh marker and lateral knee marker. The difference in this variation is that a [[Visual3D:Documentation:Modeling:Segments:Knee_Alignment_Device|Knee Alignment Device]] (KAD) is used in the static trial to define the coronal plane for the knee. Palpate the lateral epicondyles to estimate the knee flexion/extension axis. Place the KAD over the epicondyles such that the device is in line with the visualized knee flexion/extension axis. This should be done in standing position.
@@ Line 127: / Line 129: @@
 After the subject static calibration trial, remove the KAD and mark the KAD location on the lateral epicondyle with a eyeliner pencil or pen. Place a marker on that location (RKNE, LKNE). Placement of the thigh (RTHI, LTHI) markers or wands (stick on a base with an attached marker) is not critical in this case so it can be placed anywhere on the thigh.
-== Improper Placement of KAD ==
+= Improper Placement of KAD =
 The KAD can be aligned improperly or can slip after placement. If this does occur, then the knee's frontal plane will be improperly defined. Care should be taken when using the KAD. As a safety measure, it may be best practice when using the KAD to align the thigh marker correctly or use medial knee markers (which is detailed in the next section) and collect a static trial with the KAD and one without the KAD. A choice can be made post data collection on whether to use the KAD alignment or the thigh or medial knee alignment.
-=== Knee Width ===
+== Knee Width ==
 Because no medial knee marker is used, **it is critically important to measure the width of the knee** (e.g. the distance between the medial and lateral epicondyles) since this information is used to identify the distal end of the thigh segment, i.e the knee joint center.
-==== Lower Leg Markers ====
+=== Lower Leg Markers ===
-{{ShankPiG.png}}
+{{:ShankPiG.png}}
 RKJC, LKJC = Knee Joint Center
@@ Line 146: / Line 148: @@
 As in the thigh, the placement of the shank markers (RSK, LSK) or wands (stick on a base with an attached marker) is critical. This marker is used to define the coronal plane of the tibia (ankle flexion/extension axis location and orientation). The distal 1/3 of the tibia is the best location to decrease movement due to muscle bulk. The vertical height is not critical but try not place the shank marker too low on the shank. The anterior/posterior position of this marker is critical and it is extremely difficult to visualize. An alignment reference device such as a ruler under the subject's heel can be used to visualize the placement. Adjust the marker so that it is aligned in the plane that contains the knee and ankle joint centers and the ankle flexion/extension axis. This marker can be placed in a seated position but should be checked when standing to confirm.
-=== Ankle Diameter ===
+== Ankle Diameter ==
 Because no medial ankle marker is used, it is **critically important** to measure the diameter of the ankle (e.g. the distance between the medial and lateral malleolus) since this information is used to identify the distal end of the shank segment.
-==== Foot Markers ====
+=== Foot Markers ===
 The foot is visualized as a line along the long axis of the foot from the 2nd metatarsal heads and the ankle joint center projected onto the plantar surface of the foot.
@@ Line 161: / Line 163: @@
 See [[Visual3D:Tutorials:Modeling:Building_a_Conventional_Gait_Model#Enhancing_the_Foot_Segment|Enhancing the foot segment]] for more detail.
-{{FootPiG.png}}
+{{:FootPiG.png}}
 RAJC, LAJC = Ankle Joint Center
 RTOE, LTOE = Second metatarsal head
 RHEE, LHEE = Center of Calcaneus
-===== Create the Lower-Limb Plug-In Gait Model =====
+==== Create the Lower-Limb Plug-In Gait Model ====
 This section will detail the construction of the Plug-In Gait version of the Conventional Gait Model. Click [[[https://www.has-motion.com/download/examples/PlugInGaitLowerBody%20Tutorial.zip|Plug-In Gait Lower Body Tutorial.c3d]]] to download the example files. These sample files were generously provided by Vicon (OMG plc, UK).
@@ Line 173: / Line 175: @@
   - From the **Model** menu, select **Create (Add Static Calibration File)**\\
-{{tutorial1_2.jpg{{/images/e/e4/tutorial1_2.jpg?618x116}}\\
+{{:tutorial1_2.jpg}}\\
   - Select **Hybrid Model from C3DFile**
@@ Line 180: / Line 182: @@
   - Visual3D will switch to Model Building mode automatically. The 3D viewer will display the average value of the marker locations from the standing file. The dialog bar to the left of the screen will contain a list of segments, which by default will contain only a segment representing the Laboratory.
-==== Pelvis ====
+=== Pelvis ===
-{{PelvisPiG3.png}}
+{{:PelvisPiG3.png}}
-{{PelvisPiG4.png}}
+{{:PelvisPiG4.png}}
 RASI, LASI = Right Ilium Anterior Superior (Anterior Superior Iliac Spine)
@@ Line 198: / Line 200: @@
-=== Creating the SCRM landmark ===
+== Creating the SCRM landmark ==
 If you have opted for the 4-marker pelvis marker set, where both right and left posterior superior iliac spines are identified, a sacrum landmark has to be created to define the pelvis segment.
@@ Line 212: / Line 214: @@
 AXIAL=0.5
 //Check Offset By Percent//
-=== Creating the Pelvis Segment ===
+== Creating the Pelvis Segment ==
   - From the **Segment Name** box, select //Pelvis.//
   - From the **Segment Type** box, select //Coda.//
   - Click **Create.**\\
-{{CODA_pelvis1.jpg}}\\
+{{:CODA_pelvis1.jpg}}\\
 \\
   - A dialogue box labeled **Enter Body Mass and Height** will open because Visual3D needs the subject to be assigned a mass and a height. For this example, Enter //75// kg and //1.76// m, and click **OK.**\\
-{{CODA_height_%26_weight.jpg}}\\
+{{:26_weight.jpg}}\\
 \\
   - A dialogue box labeled **CODA Segment Markers** will open. Select the markers so that they correspond to the figure below. Click **Close.**\\
 **Note: as shown in the figure above, the SCRM marker (or Landmark) is used for both //R.PSIS// and //L.PSIS//\\
-{{PiGPelvisMarkers.png}}.\\
+{{:PiGPelvisMarkers.png}}.\\
 \\
 **
@@ Line 234: / Line 236: @@
 **Note: Creating a Coda Pelvis in Visual3D automatically generates the RIGHT_HIP and LEFT_HIP landmarks. However, these landmarks should simply be ignored since a different definition will be used to compute the hip joint centres (see section below).**
-=== Enter Subject Measurements ===
+== Enter Subject Measurements ==
 The Plug-In Gait conventional gait model requires measurement of leg length as well as knee and ankle width. To enter those measurements in Visual3D, a **Subject Data Metric** must be created for each measurement.\\
 **While these metrics are saved in the //Model Template// (.mdh) file, their values should be updated for each patient, to reflect patient specific measurements.**
-{{PiGRight_Leg_Length.png}}
+{{:PiGRight_Leg_Length.png}}
 \\
@@ Line 322: / Line 324: @@
   - Click on **OK**
-==== Hip Joint Center ====
+=== Hip Joint Center ===
 The Hip Joint Center regression equation for the [[Visual3D:Documentation:Modeling:Segments:Helen_Hayes_(Davis)_Pelvis|Helen Hayes (Davis) Pelvis]] is based on Leg Length, inter-ASIS Distance, and a regression for ASIS to Greater Trochanter distance.
@@ Line 354: / Line 356: @@
-=== Metrics to compute Hip Joint Center ===
+== Metrics to compute Hip Joint Center ==
 In order to create the Hip Joint center landmarks in Visual3D using the above-mentioned equations, it is highly recommended to create separate metric entries for each equation parameter. This allows the user to identify transcription errors and typos more easily. As a precaution, make sure that a value is computed in the //Value// column of each defined metrics. A //No Data// return value means a mathematical error (missing * or parentheses for example).
@@ Line 436: / Line 438: @@
-=== XYZ coordinates for the Hip Joint Center ===
+== XYZ coordinates for the Hip Joint Center ==
 **While defining/entering these metrics may appear time consuming, these are saved in the //Model Template// (.mdh) file, and so do not have to be entered for every patient/subject.**
@@ Line 494: / Line 496: @@
-=== Creating the Hip Joint Center Landmarks ===
+== Creating the Hip Joint Center Landmarks ==
 Go to the **Landmarks** tab, and click on **Add New Landmark**:
@@ Line 523: / Line 525: @@
 //Do Not Check Offset By Percent//
 **Do Not Check Calibration Only Landmark**
-==== Thigh Segment ====
+=== Thigh Segment ===
-{{ThighPiG.png}}
+{{:ThighPiG.png}}
 RHJC, LHJC = Hip joint center
 RTHI, LTHI = Lateral Thigh marker
 RKNE, LKNE = Lateral Knee marker
-=== Creating the Thigh Segment Without a Knee Alignment Device ===
+== Creating the Thigh Segment Without a Knee Alignment Device ==
-== Creating the Thigh Segments ==
+= Creating the Thigh Segments =
 Once the Hip Joint Centers have been created, the thigh segments can now be defined.
-{{PiGThigh.png}}
+{{:PiGThigh.png}}
 From the **Segment Name** list, select //Right Thigh//\\
@@ Line 562: / Line 564: @@
   - Click on **Build Model**
-=== Creating the Thigh Segment With a Knee Alignment Device ===
+== Creating the Thigh Segment With a Knee Alignment Device ==
-== Create KAD Segments ==
+= Create KAD Segments =
 We must make a virtual segment (kinematic only) for the KAD. To create a //Kinematic Only// right KAD segment:
@@ Line 573: / Line 575: @@
   - Check the **Kinematic Only** box
   - Click **Create.**\\
-[[index.php?title=Special:Upload&wpDestFile=HH_KAD_segment1.jpg|File:HH KAD segment1.jpg]]\\
+{{:HH_KAD_segment1.jpg}}\\
   - A dialogue box labeled **Helen Hayes/Derived Segment Markers** will open. Select the markers so that they correspond to the figure below. Click **Close.**\\
-[[index.php?title=Special:Upload&wpDestFile=HH_KAD_segment_markers1.jpg|File:HH KAD segment markers1.jpg]]\\
+{{:HH_KAD_segment_markers1.jpg}}\\
   - Click **Build Model** to build the segment. You should now see the KAD segment coordinate system on your standing model. If you do not see the KAD coordinate system after clicking **Build Model**, double check the values you entered in the last step.\\
-[[index.php?title=Special:Upload&wpDestFile=HH_KAD_segments.jpg|File:HH KAD segments.jpg]]\\
+{{:HH_KAD_segments.jpg}}\\
@@ Line 595: / Line 597: @@
 **Note: Many laboratories have taken to replacing the 25 mm markers with smaller markers, in an erroneous assumption that it would be a good idea to have all markers used on the body and the KAD to be the same size. This actually introduces an error in the assumptions of how the KAD is used. If this is done, the user must be careful to accommodate this change to the original assumptions.**
-== Edit Subject Metrics and Landmarks ==
+= Edit Subject Metrics and Landmarks =
 When the KAD segments are created, Visual 3D creates the Knee and Ankle width subject metrics from default values. These need to be edited to reflect the current subject. #Click on **Subject Data/Metrics** tab and enter the values by selecting **Modify Selected Item** for each of the items below:
@@ Line 609: / Line 611: @@
 The Subject Data/Metrics should look like the image below.
-[[index.php?title=Special:Upload&wpDestFile=HH_Subject_Data_Metrics_KAD_All1.jpg|File:HH Subject Data Metrics KAD All1.jpg]]
+{{:HH_Subject_Data_Metrics_KAD_All1.jpg}}
-== Create Thigh Segments ==
+= Create Thigh Segments =
 To create the right thigh segment:
@@ Line 630: / Line 632: @@
 You should now see a thigh segment on your standing model. If you do not see the thigh segment after clicking Build Model, double check the values you entered in the last step.\\
-[[index.php?title=Special:Upload&wpDestFile=HH_KAD_Thigh_segment1.jpg|File:HH KAD Thigh segment1.jpg]]
+{{:HH_KAD_Thigh_segment1.jpg}}
 To create the left thigh segment:
@@ Line 648: / Line 650: @@
   - Click on **Build Model**
-[[index.php?title=Special:Upload&wpDestFile=HH_KAD_Thigh_segment_all.jpg|File:HH KAD Thigh segment all.jpg]]
+{{:HH_KAD_Thigh_segment_all.jpg}}
-==== Shank Segment ====
+=== Shank Segment ===
-{{ShankPiG.png}}
+{{:ShankPiG.png}}
 RKJC, LKJC = Knee joint center
 RTIB, LTIB = Lateral Shank marker
 RANK, LANK= Lateral Malleolus
-=== Creating the Shank segments ===
+== Creating the Shank segments ==
-== Creating the Knee Joint Centers ==
+= Creating the Knee Joint Centers =
 First the Knee Joint Centers need to be created:
-{{PiG_RKJC.png}}
+{{:PiG_RKJC.png}}
 In the Landmarks tab, click on **Add New Landmark**.
@@ Line 683: / Line 685: @@
 Once the Knee Joint Centers have been created, the Shank segments can now be defined.
-== Defining the Shank Segments ==
+= Defining the Shank Segments =
-{{PiGShank.png}}
+{{:PiGShank.png}}
 From the **Segment Name** list, select //Right Shank//\\
@@ Line 711: / Line 713: @@
   - Click on **Build Model**
-==== Foot Segments ====
+=== Foot Segments ===
-{{FootPiG.png}}
+{{:FootPiG.png}}
 RAJC, LAJC = Ankle Joint Center
 RTOE, LTOE = Second metatarsal head
 RHEE, LHEE = Center of Calcaneus
-=== Creating the Foot Segments ===
+== Creating the Foot Segments ==
-== Creating the Ankle Joint Centers ==
+= Creating the Ankle Joint Centers =
 First the Ankle Joint Centers need to be created:
-{{PiG_RAJC.png}}
+{{:PiG_RAJC.png}}
 In the Landmarks tab, click on **Add New Landmark**.
@@ Line 744: / Line 746: @@
 Once the Ankle Joint Centers have been created, the Foot segments can now be defined.
-== Defining the Foot Segments ==
+= Defining the Foot Segments =
-{{PiGFoot.png}}
+{{:PiGFoot.png}}
 From the **Segment Name** list, select //Right Foot//\\
@@ Line 774: / Line 776: @@
-== Defining the Virtual Foot Segments ==
+= Defining the Virtual Foot Segments =
-{{PiGVFoot.png}}
+{{:PiGVFoot.png}}
 In the **Segment Name** list, enter //Right Virtual Foot//\\
@@ Line 804: / Line 806: @@
   - Click on **Build Model**
-== Rotate Local Coordinate System ==
+= Rotate Local Coordinate System =
 Once the Virtual Foot Segment are created, their corresponding local coordinate system must be modified to be aligned with the other segment's coordinate systems.
@@ Line 823: / Line 825: @@
-{{PiGRotateRMF.png}}
+{{:PiGRotateRMF.png}}
-===== Export to Vicon Polygon =====
+==== Export to Vicon Polygon ====
-==== Verifying Force Assignments ====
+=== Verifying Force Assignments ===
 [[Visual3D:Documentation:Kinematics_and_Kinetics:External_Forces:Force_Assignment|Force Assignment]]
-==== Basic Signal Processing ====
+=== Basic Signal Processing ===
 [[Visual3D:Tutorials:Knowledge_Discovery:Signal_Processing|Tutorial: Signal Processing]]
-==== Computing Gait Events ====
+=== Computing Gait Events ===
 [[Visual3D:Documentation:Pipeline:Event_Commands:Automatic_Gait_Events|Automatic Gait Events]]
-==== Computing Joint Angles ====
+=== Computing Joint Angles ===
-==== Computing Joint Moments ====
+=== Computing Joint Moments ===
-==== Export the Polygon C3D file ====
+=== Export the Polygon C3D file ===
-===== References =====
+==== References ====
 **Bell AL, Pederson DR, and Brand RA** (1989) Prediction of hip joint center location from external landmarks. Human Movement Science. 8:3-16