Coding

Rotation Flap Calculator (Github)

One of the common types of local flaps used are rotation flaps. These types of flaps utilize the ability of a local skin flap to advance over a defect usually made from the excision of a lesion. The goal of this code is to ease pre-operative measurement calculations and aid in visualization of flap design and ensure appropriate flap length to cover the patient defect. Below is a diagram describing common geometry of rotational flap design where the grey circle represents the defect and the blue line is the arc of advancement.

In order to ease the pre-operative drawing of this flap design the user can input the diameter of the defect (in the above diagram this value is x). Users are prompted to use a value between 1-10, any unit is appropriate as all calculations are based on a ratio. Next the user is prompted to click repair.

For example, for a defect of 5cm diameter. The user will input this in the above line and click repair. The following output is then generated.

The image output shows the following:

• a red circle representing the original defect

• a dotted triangle representing the defect excision

• a solid black line representing the lower bound of the arc length as defined in the initial diagram as 5 x defect diameter

• a dotted black line representing the upper bound of the arc length as defined in the initial diagram as 8 x defect diameter

Additionally, and more applicable to the surgeon's drawing is the text output at the top of the UI. This shows the x and y distances from the central pivot point to the endpoint of the lower bound of the arc length (grey) and the upper bound of the arc length (green). The surgeon can then connect this point to the triangular defect excision via an an estimated arc and be assured they will have enough mobilized tissue to cover the defect.