Clinical Measures
This page explains all relevant features on the Clinical Measures page of LaserCAM Prescribe.
Navigation
Click Clinical Measures from the menu to access this page in LaserCAM Prescribe.
Page Layout
Page Fields
Scan Angle
The Scan Angle specifies the alignment of the foot in the frontal plane relative to a provided reference position and is specified in degrees.
You cannot use Scan Angle as your reference alignment if you capture non-colour STL files unless you also provide a Forefoot Varus or Forefoot Valgus measurement. If your scanner captures a visible heel bisection then Scan Angle is an Acceptable Reference Measurement.
Default Value | Minimum Value | Maximum Value |
|---|---|---|
0° | -45° (Eversion) | 45° (Inversion) |
A positive value indicates an inversion of the 3D foot scan relative to its reference position.
Increasing the inversion angle will increase medial arch height, medial heel wedging and total medial support of the orthosis.
A negative value indicates an eversion of the 3D foot scan relative to its reference position.
Increasing the eversion angle will increase lateral arch height, lateral heel wedging and total lateral support of the orthosis.
Forefoot Varus
The Forefoot Varus specifies the alignment of the 3D foot scan. This measurement is a pre-requisite if you do not capture a scan with a heel bisection.
Default Value | Minimum Value | Maximum Value |
|---|---|---|
0° | 0° | 45° |
A captured Forefoot Varus may be maintained intrinsically within a Machined EVA orthosis. For more information refer to Maintain Forefoot Varus/Valgus on the Device Options help page for Machined EVA orthoses.
The image below shows a 7.5 degree Forefoot Varus. This measurement is then used to align the 3D scan in the frontal plane.
Make sure that you accurately measure the Forefoot Varus as this has significant effects on the orthosis.
Forefoot Valgus
The Forefoot Valgus specifies the alignment of the 3D foot scan. This measurement is a pre-requisite if you do not capture a scan with a heel bisection.
Default Value | Minimum Value | Maximum Value |
|---|---|---|
0° | 0° | 45° |
A captured Forefoot Valgus can be maintained intrinsically within a Machined EVA orthosis.
The image below shows a 10 degree Forefoot Valgus. This measurement is then used to align the 3D scan in the frontal plane.
Make sure that you accurately measure the Forefoot Valgus as this has significant effects on the morphology of the manufactured orthosis.
Heel Centre to 1st MPJ Centre
A measurement from the centre of the heel to the 1st MPJ can be entered in this field. This clinical measurement is used to calibrate a 3D scan. This is only possible with colour 3D scan formats.
If your scanner does not capture a highly accurate 3D scan, but still captures colour information then we recommend inputting data in this field to allow for calibration of the 3D scan during computer-aided design.
Default Value | Minimum Value | Maximum Value |
|---|---|---|
0mm | 0mm | 250mm |
The image below shows a 142mm Heel Centre to 1st MPJ Centre.
In the image below the digital measurement of the Heel Centre to 1st MPJ Centre is 141.9mm.
This digital measurement is then used to calibrate the 3D scan.
Some 3D scanners will be significantly more inaccurate than the example provided above.
What can happen if I don't provide this measurement?
Incorrectly scaled 3D scan leading to poor fit and contouring to foot.
Incorrect placement of additions on top surface of orthosis.
Providing this measurement will help to reduce these potential errors.
Posterior Heel to Heel Centre
A measurement from the most posterior point of the heel to the centre of the heel measured with a LaserCAM Goniometer. This measurement is used to position a 3D scan in the sagittal plane during computer-aided design.
Default Value | Minimum Value | Maximum Value |
|---|---|---|
0mm | 0mm | 100mm |
You do not need to capture this measurement if you scan with the LaserCAM VPS. This measurement is a prerequisite for all scanners that do not accurately capture the posterior aspect of the heel. Without this information a 3D scan cannot be accurately positioned in 3D space, which can lead to negative clinical implications.
The image below shows a 35mm Posterior Heel to Heel Centre measurement as captured in the clinic.
The measurement device above is called a LaserCAM Goniometer.
The image below shows the digital measurement being utilised during computer-aided design.
What can happen if I don't provide this measurement?
Foot sitting too proximally on orthosis within footwear.
Foot sitting too distally on orthosis within footwear.
Shortened length of MLA and LLA.
Extended length of MLA and LLA.
Providing this measurement will help to reduce these potential errors.
Acceptable Reference Measurement
Providing an Acceptable Reference Measurement is a critical step in orthosis prescription. We will provide some examples below.
Make sure you understand which Acceptable Reference Measurement is appropriate for your choice of 3D scanner.
Scan Angle Method
You can use the Scan Angle Method if your 3D scanner:
Captures a per-vertex colour scan.
Captures the posterior heel bisection that is marked on the foot prior to scan capture.
Mark Heel Bisection
Mark a heel bisection on the patient's foot.
A reliability study by LaPointe (2001) demonstrated that the clinical bisection technique has poor inter-rater reliability (mean error of 6° (±1°)) and poor validity. This however is of no concern, as the purpose of this measurement is to provide an Acceptable Reference Measurement throughout the computer-aided design process. The Scan Angle can be inverted or everted upon the clinicians request and essentially any line on the back of the heel can be used as a reference.
Capture/Import 3D Scan
Capture, or import a 3D scan of the patients foot into the 3D Scans page of LaserCAM Prescribe.
Make sure you have a good view of the posterior heel when capturing the 3D scan.
Measure Heel Bisection
After capturing or importing a scan into the 3D Scans page in LaserCAM Prescribe, view the scan from the posterior heel view.
Orientate the scan into your preferred alignment by left clicking the display and rotating the scan.
Rotating in small clockwise, or counter-clockwise circles is the easiest way to orientate the 3D scan on the display.
Use the Right Angle Measurement tool to measure with reference to the ground plane.
In the image above the measurement is 90°.
If this is the preferred frontal plane alignment, then the Scan Angle on the Clinical Measures page will be 0°.
It is the health care professionals responsibility to provide an accurate, valid and verifiable measurement.
Specify Scan Angle
Open the Clinical Measures page and enter your required Scan Angle.
Forefoot Varus/Valgus Method
The Forefoot Varus/Forefoot Valgus Method is the required method for 3D scanners that do not capture per-vertex colour.
If your scanner captures 3D colour then you can still use this method if you find it gives you greater control over your prescription.
Capture/Import 3D Scan
Capture, or import a 3D scan of the patients foot into the 3D Scans page of LaserCAM Prescribe.
We recommend that a health care professional consider the correction of the forefoot relative to the rearfoot during 3D scan capture.
Pre-Correction Forefoot Supinatus
Post-Correction Forefoot Supinatus
Measure Forefoot Varus/Valgus
Use the Measure Angle or Measure Right Angle tools to measure the Forefoot Varus or Forefoot Valgus that has been captured.
In the image above the measurement shows an 8.5° Forefoot Varus.
The alignment of the 3D scan above is an example only and will not necessarily represent any particular patient.
Specify Forefoot Varus/Valgus Angle
Open the Clinical Measures page and enter your required measurement.
Combining Measurements
If both Scan Angle and Forefoot Varus/Valgus are specified then both will be used.
The Scan Angle will always be the second measurement applied during alignment, with the Forefoot Varus/Valgus measurement specifying the initial frontal plane orientation of the foot scan during computer-aided design.
For example, in the image below a Scan Angle of 4° (Inversion) has been requested in combination with an 11° Forefoot Varus.
The subsequent alignment can be seen below, showing a final Forefoot Varus alignment of 15°.
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