Review of a Slash and Overlap Method to Alter Patterns for Knock Knees

One of the cool features of VStitcher is being able to move the avatar into different positions. One of the positions I thought would be helpful to understand fit is a subtle knock-knees stance.

Knee Alignment

I’m going to ignore bowlegs since that issue is less frequent. However, the approach can be applied similarly if needed. For regular anatomical alignment, the center of the ankle, the center of the knee, and the center of the hip can all be aligned along the same vertical line. However, with knock knees, when the ankle and hip are aligned, the center of the knee will deflect toward the midline.

I choose only a 3% knee deflection on my avatar to explore fit changes. The avatar knock-knees are the same across patterns.

Slash and Overlap

To make an alteration for knock-knees, I used a slash and overlap method at the knee level. Cutting along the horizontal knee level, overlap along the side seam the amount needed leaving the inseam untouched. How to determine the amount to overlap? You may be able to pinch out the excess on a muslin. The goal is to get the hem parallel with the ground if it’s a wider leg or to get the center grainline centered with your ankle if the leg is more narrow.

Knock-knee adjustments should be made after adjusting the center grainline at the hip. Why? Adjusting the center grainline at the hip impacts the fit from the hip down. Knock-knees only impact fit from the knee down. You want to fit pants starting at the top and working down because alterations at the top will cascade down and change the fit. Let’s look at three patterns to see how the alteration is made and the impact on fit.

May Jeans from Make by TFS

Knock-Knees Alteration

May Jeans Knock-Knees Alteration

Using the slash and overlap method, I only had to overlap 0.375 inches at the side seam. The key point to getting this alignment was to focus on the hem. I wanted the hem parallel to the floor, and I wanted the hem to not be touching along the inseam. Notice that the center grainline is still in the middle of the ankle and knee level! The center grainline will NOT be perpendicular to the floor from the ankle to the knee. The center grainline is only perpendicular from the knee upward.

Avatars Across Alterations

In the following images, I show the knock-knees and anatomically aligned avatars across the adjustments previously made. For a full review of alterations, visit my blog post here. Briefly, I made sure the center grainline bisected the knee reference line. Next, I adjusted the center grainline placement at the hip so the legs would hang straight. Finally, I adjusted the lower leg using the slash and overlap method.

Front View
45º View
Side View
135º View
Back View

The view from the back is the clearest. The hem on the knock-knees adjusted grainline is not parallel to the floor. The hem is also touching along the inseam. However, the spread and overlap adjustment changes the hem, so it is parallel to the floor, and the inside is no longer touching.

Ginger Jeans from Closet Core Patterns

Knock-Knees Alteration

Ginger Jeans Knock-Knees Alteration

Using the slash and overlap method, I only had to overlap 0.5 inches at the side seam. I wanted the center of the hem to line up with the center of the ankle. This alteration also removed some of the draglines from the front and side of the knee. Notice that the center grainline is still in the middle of the ankle and knee level! The center grainline will NOT be perpendicular to the floor from the ankle to the knee. The center grainline is only perpendicular from the knee upward.

Avatars Across Alterations

In the following images, I show the knock-knees and anatomically aligned avatars across the adjustments previously made. For a full review of alterations, visit my previous blog post here. Briefly, I made sure the center grainline bisected the knee reference line. Next, I adjusted the center grainline placement at the hip so the legs would hang straight. Finally, I adjusted the lower leg using the slash and overlap method.

Front View
45º View
Side View

The draglines around the front of the knee are finally removed with the slash and overlap method. The knock-knees avatar and aligned knees avatar have a similar fit in the end, even though that fit includes wrinkles.

135º View
Back View

The center grainline is not aligned with the back of the foot until the slash and overlap method is done. Prior the center grainline hung towards the inseam.

Brassie Joggers from Green Style

Alteration

Brassie Joggers Knock-Knees Alteration

Using the slash and overlap method, I only had to overlap 1 inch at the side seam. The key point to getting this alignment was to focus on the hem. I wanted the center of the hem to line up with the center of the ankle. This alteration also removed some of the draglines from the front and side of the knee. Notice that the center grainline is still in the middle of the ankle and knee level! The center grainline will NOT be perpendicular to the floor from the ankle to the knee. The center grainline is only perpendicular from the knee upward.

Avatars Across Alterations

In the following images, I show the knock-knees and anatomically aligned avatars across the adjustments previously made. For a full review of alterations, visit my previous blog post here. Briefly, I adjusted the lower leg using the slash and overlap method. I didn’t need to bisect the knee since the pattern was already drafted that way.

Front View
45º View
Side View

The most notable change was in this view. The draglines along the side and front of the knee are eliminated when the slash and overlap alteration is completed.

135º View
Back View

Suggestions

Just like adjusting the center grainline placement at the hip, altering patterns for knock-knees is driven by the pattern and the shape of the lower leg. It appears from these data the wider the leg, the less adjustment is needed. The narrower and tighter the leg, the more adjustment may be needed. With wider legs, focus on the hem and whether it is parallel to the floor and not touching along the inseam. With narrower legs, focus on the draglines in the front and to the side seam. You may even be able to pinch out some of the excess fabric along the side of the knee to determine how much to slash and overlap.

How to alter the center grainline at the hip when the knee doesn’t align with the foot and ankle? Please review my previous post about using a laser level and body alignment. If you are standing with your feet hip-width apart and your second toe is aligned with your ankle, you can determine how far the center of your knee is from the laser level. Take some wide paper like wrapping paper and trace your feet so you know how to stand each time you try fitting slacks with a laser level. On the paper with your feet traced, write down the distance between the laser level and the center of your knee. When marking your knee on the muslin, mark that distance away from the center of your knee to optimize alignment with the laser level.

Possible Limitation

The only other post I could find was this post. They placed the pivot point in the middle of the knee so the inseam is lengthened and the side seam is shortened. The hem on the inseam side is shortened because of the added length. I was not able to determine if you have to adjust the hem after slashing and overlapping. My method leaves the inseam length as is since the pivot point is on the inside of the knee and only removes the excess length along the side seam. I tried lengthening the hem along the side seam so that the hem is parallel with the floor and couldn’t determine if it helped fit. This is where real-world testing is needed.

Conclusions

I hope this was helpful and informative about a possible method for addressing knock-knees. I definitely learned a lot about fitting slacks, and I feel more confident using the Browzwear app. Enjoy!

9 thoughts on “Review of a Slash and Overlap Method to Alter Patterns for Knock Knees

Add yours

  1. So interesting to see all these comparisons! Thanks for putting the time in. If you ever have the energy/inclination, I’d be curious to see how fit is affected by the leg alignment where the knees are inwards, in relation to the hip point, but the ankle doesn’t go back outwards (not sure what this is called?).

    Liked by 1 person

      1. Ah ok. The q-angle impacts the shape of your torso region (are you more ellipsoid or circular in your lower body), which corresponds to the placement of the center grainline at the hip. The q-angle can sometimes result in an unbalanced knee (i.e., knock-knees), but not always. I emphasize that ankles should be in line with the hip when standing for a reason. With the ankle and hip aligned, you can determine if your knee’s center is inline, inward (knock knees), or outward (bow legs). Just because you might have an abnormal q angle, that should only impact center grainline line placement at the hips. Knee alignment is a separate thing. Torso shape is a big reason why pant patterns will never look the same on everyone. 3D body scan research is just beginning to unpack shape differences and fit.

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  2. This is really helpful. I never realized I have knock knees. Like many, it is a small angle. I’m going to buy a laser level to help myself figure out the angles since I don’t have anyone to help me with fitting.
    The Avatars showing the different views with different adjustments are really helpful. They work well for the way my mind works.
    Thanks!

    Liked by 1 person

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