Palmer Pletsch and trousers.

[Tiggy]

I have spent an enormous amount of mental energy trying to figure out the diagonal wrinkles I get on the backs of my trousers going from hip to inside thigh/knee.  I tried the tissue fitting technique of putting a pleat in the pattern up the back and while it works on the back of my leg, it makes the hip and the waist band far too small.  Just for completeness, does anybody know what I’m doing wrong?

(Incidentally, I have found that by unpicking the inside seam to the knee of each leg and part of the rise, I can pull part of the back leg through enough to remove the wrinkles.  Basically, I am shortening the rear crotch length if that makes sense.   (A tip from Pamela Howard in Threads magazine).  It doesn’t mess up the hip or the waist either.)

[toileandtrouble]

Seen that crease on OHs trousers.  The crotch seam may need scooping about 1/4" lower at the back.  Our bottoms sadly tend to get lower as we age.

[Ohsewsimple]

Have you got any photos @Tiggy.  There are lots of different variations of these wrinkles 
My first thought was the back crutch fork needs lengthening. 

[Greybird]

Not sure about your particular wrinkling issue, but several years ago I made an Ann Ladbury trouser block. I have used it in conjunction with any trouser pattern I have liked ever since. What I have found is that the distance from the crotch point to the side seam on the patterns is way too long for me. I have a fairly average sized bum, neither too small or, surprisingly, too big. The pattern makers seem to assume, however, that we all have very big bums. My trouser block has turned out to be one of the best things I have ever done.

[Helen M]

Seen that crease on OHs trousers.  The crotch seam may need scooping about 1/4" lower at the back.  Our bottoms sadly tend to get lower as we age.

I was thinking the same.

I thought I had a link about 'crotch width - what causes crotch smiles' from 7pine designs but the link is dead. I think I found it on her Facebook page but can't seem to find that either right now. Basically from memory it is the width that forms in the U that you see if you lie back and front pattern pieces. I think you extended the 'hook' on the back piece.

Maybe a timely reminder to check out your 'old' saved links........

I've made a similar adjustment by letting out leg inner seam on RTW pants.

[Ploshkin]

Is the outside leg seam vertical?  If not I would be inclined to correct that first as it could make a difference to other changes that are required.

[PollyWally]

Closet Core Patterns has a pants fitting guide. Pants Fitting Adjustments Not sure if that could give you any clues on fixing your issues.