Last updated on December 19 2023
Description
The Knee Osteotomy procedure can be used to correct an abnormal size, shape, position or composition of the leg. To perform the leg alignment, it is needed to have knowledge of anatomical measurements and provide the anatomical and mechanical axes of deformed limbs, which are compared to standard values, to later simulate corrective procedures.
The Knee Osteotomy procedure will advise the user to perform a correctional procedure depending on the calculated measurements.
The system will determine if there is any deformity. If one is detected, the system will suggest the type of osteotomy to be performed - High Tibial Osteotomy (HTO), Distal Femoral Osteotomy (DFO) or both - and make the necessary corrections.
Requirements
To perform this procedure, a CR of the full leg is required.
Measurements
In this procedure, there are several parameters to analyze:
- Joint Line Congruence Angle (JLCA): the angle between the lines of the femur and tibia
plateaus. - Joint Line Obliquity (JLO): the angle between the tibial plateau line and a horizontal line that is perpendicular to the vertical line of the medical image.
- Weight Bearing Angle (WBA): the angle between the center of the femoral head to the Weight Bearing Position (WBP) and the WBP to the midpoint of the tibial distal articular surface.
- Weight Bearing Position (WBP): percentage where the mechanical axis line crosses the tibial plateau line;
- Mechanical Lateral Distal Femoral Angle (mLDFA): the angle between the tangent line to the femoral condyles and the femoral mechanical axis, measured on the lateral side;
- Mechanical Medial Proximal Tibial Angle (mMPTA): the angle between the tibial plateau and the tibial mechanical axis, measured on the medial side;
- Mechanical Tibiofemoral Angle (mTFA): The angle between the line from the center of the femoral head to the center of the femoral articular surface and the line from the center of the tibial plateau to the center of the tibial distal articular surface.
Auxiliary references
To show this procedure, PeekMed® needs additional references, not shown to the user, but relevant for planning:
- Mechanical Axis of the Tibia (MAT): is the tibial length, i. e., the length between the tangent line of the tibial distal articular surface and the midpoint of the tibial plateau;
- Mechanical Axis (MA): the total leg length, i. e., the length between the center of the femoral head and the tangent line of the tibial distal articular surface;
- Mechanical Axis of the Femur (MAF): is the femur length, i. e., the length between the center of the femoral head and the midpoint of the femur plateau.
How to perform
Pre-op stage
- Validate landmarks and consult measurements
After creating the case and uploading the image, all the relevant landmarks will be automatically placed, and you will be able to view the pre-operative values of each measurement.
At this point, you can adjust the position of the landmarks if needed. Just click "Edit landmarks" , adjust the position, and then save the changes by clicking "Save".
The measurements will then be updated based on your adjustments and you can proceed to the next step by clicking “Approve”.
Note: To change the position of the landmarks, you should hover the mouse over the landmark and then use the left mouse button to move each handle to the most suitable position.
- Edit WBP
Due to the impact on recovery and on the planning, you may set a WBP aim. You can use the slider to set the value and the WBP will be updated in the renderer.
Plan stage
When you enter the plan stage, two outcomes are possible. Either the osteotomy criteria is reached (i.e. values are outside the normal range and PeekMed Web suggests an approach) or not reached (i.e. the values considered for planning are within normal range).
Regardless of the scenario, you can always consult the measurements associated with the procedure by clicking on 
.
Note: Please note that it is not possible to edit the landmarks position after measurement approval.
When the osteotomy criteria is NOT reached
The system will not perform any action. You may “Approve” this feedback and end the plan. You will then be taken to the Export state.
When the osteotomy criteria is reached
PeekMed Web performs the suggested knee osteotomy.
The medical image is cut and the segmented bones aligned. The suggested osteotomy type is identified on the floating window, and here you can adjust the length/angle of the wedge. If you agree with the suggestion, you may finish the plan by clicking “Approve”. Otherwise, you can use the “Redo” menu to make changes in the planning.
In the “Redo” window, the medical image and calculations are returned to their initial state. Here, you may alter the Weight-bearing line position, consider the JLCA (when available) and select an alternative knee osteotomy type. The Weight-bearing line position and the JLCA may have an impact on the alternative knee osteotomy type made available to you, thus these two factors must be considered before deciding on a knee osteotomy type. Be sure to click “Apply changes” after selecting an alternative osteotomy type to save your selection.
If you wish to discard your adjustments and continue with the default suggestion, just click "Back".
Once you are finished editing, click “Validate” to complete and save your changes. You will then be able to adjust the length and angle of the wedge again and approve the procedure.
After approving the procedure, you will move on to the templating stage. You can start by choosing the manufacturer you want to use. If only one manufacturer is available, it will be selected by default.
In the template configuration stage you can modify the properties of the template(s) as well as their position.
To approve the plan, the user must click "Approve plan" and confirm the action in the dialog window.
Export stage
The last step of the planning process will be the Export. Here you can download a PDF report where all the planning information is identified.