OrthoLoad Videos

Video format

The older OrthoLoad videos have a frame rate of 25 fps (time resolution = 0.04 s). Newer videos run at a speed of 50 fps (time resolution = 0.02 s).

Video size

All OrthoLoad videos have a size of 1024×768 pixels. In order to see them in best quality in a media player, choose Zoom = 100%. On a notebook with a resolution of 1024×768 pixels you should play the videos in the ‘Full Screen’ modus.

Video codec

We encode all files using the Windows Media Encoder 9 which produces files in the wmv-format (Windows Media Video). The quality and file size are at least as good as those of avi-files using the DivX or Xvid codec. The wmv- codec is supplied with each Windows installation from Windows XP onwards. In nearly all cases the OrthoLoad videos therefore run on Windows computers without any difficulties. This is an advantage as no additional codec must be installed on your PC, and the videos almost always run in PowerPoint presentations. If the wmv-codec is not installed on your PC, you can download it. Or you can download the newest version of the Windows Media Player which includes the wmv codec (see comments on the Windows Media Player).

Furthermore, we convert all OrthoLoad videos in the mp4-video format(H.264) using ffmpeg codec library. You can play mp4-videos on Windows, Mac OS X and Linux computers with VLC player. We suggest VLC Player 2.0 or higher.

Conversion of wmv video format

If you want to convert an OrthoLoad video to another format, for example to an avi-file with the Xvid-codec, we suggest that you use the free conversion program ‘Super’.

Media player

These are some popular free video players:

Media Player Classic

This simple player must not be installed. It plays 25 fps and 50 fps videos at a correct speed and you can study movements in detail frame by frame by using the arrow key button (forwards only !). The time counter has a resolution of only 1s, but the precise time is shown in the small table ‘Video’ & ‘Time Now’ in the OrthoLoad videos. You can open several instances of the program at the same time, for example if you would like to compare different exercises.

FairPlay Lite

This player is very small, easy to handle and for free. Installation is not required. 50 fps videos are shown at correct speed and you can proceed with the arrow keys. The time counter has a resolution of 0.02s (50 fps). Several instances of the player can be opened.

Windows Media Player

This player is installed together with Windows. It does play 50 fps videos, but it is overloaded with features, and it is difficult to select a single video frame using the mouse. Proceeding frame-by-frame is not possible. The time counter has a resolution of only 1s.

VLC media player

VLC player is a powerfull open source media player für Windows, Mac OS X and Linux. It plays 25 fps and 50 fps videos at a correct speed and you can study movements in detail frame by frame by using the hotkey ‘e’ (see ‘Tools/Options/Hotkeys’).

Other Video Players

Kinovea can be used to play 2 videos synchronously. It doesn’t work properly with wmv-videos, however.

We suggest

Use of the Media Player Classic or FairPlay Lite as the Standard Video Player for the wmv-video format (Windows). Use of the VLC media player as the Standard Video Player for the mp4-video format (Windows, Mac OS X, Linux).

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Introduction

What is OrthoLoad?

OrthoLoad is a public database containing the loads acting in orthopaedic implants. They were measured in vivo using instrumented implants with telemetric data transmission. Currently load data are available for the

Hip joint, shoulder joint, knee joint, vertebral body replacement and internal spinal fixator.

Data is presented as videos, containing the time-dependent forces and moments, force vectors, video images of the patients activity and numerical data. Many results involving the ‘Hip Joint’ are already available in the database. More data are continuously added from the actual ‘Hip Joint III’ where also the three moments were measured. From hip and knee implants, only selected examples are available because access to this data must be detained until it has been published in scientific journals.

From the OrthoLoad database you can select an implant, an activity with parameters, a patient and one or several trials. The time course of the loads is shown in videos (encoded in the wmv- or mp4-format) and can be analyzed in more detail by displaying single video frames. Numerical data files (text files, suffix .akf) can additionally be downloaded and the forces and moments then be used in finite element studies or joint simulators, for example.

It’s recomended to run OrthoLoad on a Windows PCs with Media Player Classic, VLC Player or FairPlay Lite player or on Linux/Mac OS X with VLC Player!

 

How to use OrthoLoad?

Structure of an ORTHOLOAD
Video

Enter DATABASE and in the top left frame ‘Joint Loads’ you can choose an ‘Implant’ type, an ‘Activity’,  possibly an additional ‘Parameter’, a ‘Patient’ and a trial by ‘File Name’. Then an OrthoLoad video will be shown on the right frame ‘Now Selected’.

Alternatively you may select a trial directly by typing its basic trial number into the upper right frame ‘Select Video by File Name’. The basic trial number is the first part of the file name e.g. ‘s1r_211005_1_80′ of the file ‘s1r_211005_1_80_screen.mp4′

 (s1r = shoulder patient #1 with implant at the right side, _211005 = date: October 21st 2005, _1_80 = internal trial number _screen = video file, _fmax = png-image)

Use the buttons in the top left frame ‘Joint Loads’ to play, show or download videos, data or pictures. You may just play the video in your browser with Flash Plug-in. Or you download and play the video on your computer with your standard video player. We clearly favour the ‘Media Player Classic’ or ‘VLC Player’ for MS Windows and ‘VLC Player’ for Mac OS X and Linux. Videos are encoded in the wmv or mp4(H.264) format.

The vertical marker line inside the force diagram shows the actual measuring time. All other data is displayed synchronously to this time (patient video, vectors, tables …).

The ‘Hip Joint’ was instrumented with a 4-channel telemetry transmitter and only the forces were measured, no moment diagram is shown. All other implants measure forces and moments with measuring units %BW and %BW*m. Using the patients’ body weight (BW), the values in N and Nm can be recalculated.

To show or download a data file *.akf belonging to the video *.wmv or *.mp4 use the buttons ‘Show’ or ‘Download’ in the top left frame ‘Joint Loads’.

‘Additional Data’ *.eof, *.cof etc. synchronized to the video file is available for some trials

Measurements

A coil for the inductive power supply is arranged around the implant and the antenna is placed close to it. The data received is at first controlled in regard to transmission errors and then led to a notebook where the forces and moments are calculated and displayed in real time. The images of the patients’ exercises and the synchronous data stream are both recorded on the same video tape. On a monitor or using a video beamer, the forces and moments can be controlled immediately. This allows one to detect unexpected loading situations and immediately modify the way an exercise is performed.

Measurements

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Measuring set-up

During the measurements, a power induction coil and a receiver antenna are fixed near the patient’s implant. The implanted telemetry transmitter is powered inductively by the external magnetic field. The signals measured were transmitted to the external device TELEPORT for on-line force display on a notebook screen. The activities of the patient are videotaped, and the data from the implants are recorded simultaneously on the audio tracks of the same cassette.

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Additional Load Data

Example AKF

Numerical data files

For each OrthoLoad video *.wmv, an additional numerical data file *.akf exists. The data in k2l_140607_1_9.akf, for example, belongs to the video k2l_140607_1_9_screen.wmv. The video frame rate is only 25 or 50 Hz and thus the load values seen in the bottom left table of the OrthoLoad video are available at this rate, too. The loads from the instrumented implants were measured at the much higher sampling rate of typically 120 Hz. They are stored in the akf files, which can be opened with any text editor. Small time shifts between the videos and the numerical data can exist. They were compensated for during production of the OrthoLoad videos.

The data in the akf-files are self-explanatory. ‘Marker’ is a signal used to synchronize the telemetric data with external measurements and is of no use to you. The time is given in seconds. Forces or moments are not listed in %BW or %BW*m, as in the OrthoLoad videos (more info). Instead, they are given in measuring units N or Nm in the akf-files. Because the body weight on the measuring day is also stated in the akf-files, you can easily transform the units to %BW or %BW*m. Just divide them by one percent of the body weight [N]. A force of 1000N in a patient with a body weight of 870N (88.7kg), for example, equals the force of 114.9 %BW.10 Nm then corresponds to a moment of 1.15 %BW*m.

If you want, you can directly apply the numerical data, i.e. the time-dependent forces and/or moments in finite element studies or in joint simulators.

You can access each file separately (button ‘Download’ in the frame ‘Additional Data File’).

Data collection ‘HIP98‘

Hip98 Screen

The data collection HIP98 contains the forces acting in the hip joint during the most common activities of daily living. Measurements were taken in 1998 in 4 subjects. In addition to the implant loads and the synchronous videos of the subjects (as in OrthoLoad), this database provides gait analysis data, calculated muscle forces, EMG signals and numbers for the frequencies of the different activities (show abstract of Bergmann et al., 2001 (http://www.ncbi.nlm.nih.gov/pubmed/11410170?dopt=Abstract)).

The forces acting at the acetabulum, i. e. the pelvic side of the hip joint, were additionally determined, using the forces acting relative to the femur plus the belonging gait analysis data. From the results of the individuals, the loads acting in a ‘typical’ or representative subject are also provided (download HIP98 (http://www.orthoload.com/wp-content/files/uploads/hip98.zip)).

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New Publication: Analysis of hip joint loading during walking with different shoe types using instrumented total hip prostheses

Palmowski Y., Popović S., Kosack D., Damm P. 
Analysis of hip joint loading during walking with different shoe types using instrumented total hip prostheses
Scientific Reports, 2021
https//doi/10.1038/s41598-021-89611-8

Find examples in the OrthoLoad Database under Implant “Hip Joint III” – Activity “Footwear” or use the keyword “footwear” at the full-text search in the database

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