Hi @Yorkshire coop, how is the chick doing?
It looks like you taped for splayed leg -- which makes sense. If the chick has a slipped tendon, it will probably need to have the hock joint taped while it heals.
You can check for a slipped tendon from behind the bird -- looking at the back of the hock joint. When the leg is bent, the tendon slips off to the inside, taking a shorter path. When the leg is extended straight, the tendon will slip right back into place, either on its own or with a little nudge. But keeping there is challenging.
In chicks, the groove that holds the achilles tendon in place as it travels along the back of the joint is not as deep as on an adult bird. Taping it in place for a few days (5 is what the vet recommended for mine) gives it a chance to heal. It also lets those bone grooves develop more. The tendon may also shorten a bit, which helps it stay in place, or at any rate, it doesn't get overstretched while the leg is taped.
The first thing to know about the taping is that taping around the leg will not work. Instead, you will make a flat splint -- flat like an envelope -- using wide adhesive tape. One piece goes on each side, sticky sides face each other and stick down. You want the leg extended mostly straight, with a little bend in it, so the tendon stays in place. I did one yesterday and found that it helped to put the inside piece of tape on first. This is a job that goes better with two people. More instructions below.
Here's a picture of the splint the vet made:
Here's a picture of one I did on a different bird yesterday:
First, you need wide cloth adhesive bandage tape -- if your tape is very thin or flexible, you can build it up with multiple layers. Start with the two pieces facing each other (outside & inside), so it makes an envelope shape with the knife edge of the envelope lined up with the big toe -- facing forward and backward. So looking straight on is like looking at the edge of the knife. At this point, it will be large, approximate rectangles. Put as many layers as needed to hold firm, make sure the leg is at a good angle (slight bend, mostly straight) and crimp the tape together so it sticks to the opposite side and conforms to the shape of the leg.
Once it is a good envelope, take your scissors and trim off the excess tape closer to the shape of the leg. Then take small strips of tape and overlap the edge, reaching to about the middle or a little past on each side of the envelope. Cover both the front and back knife edges to keep the tape strips from separating and add stability. You can see the vet managed to put a little twist in hers that matches the placement of a chick's leg naturally. (There's a reason vets get the big bucks!).
Try to keep it on for five days. Check to see if it needs more when you take it off.
The chick will eventually learn to stand up while the splint is on, using the other leg. I tried making chick chairs, but I have peafowl with big strong legs, and the chick just tore up the chair/pen/feed/water... and hurt himself.
The chick I am treating now is doing better -- I'm syringe feeding it which is helping. It has also started drinking water on its own. Chicks aren't very mobile in the tape splints, so be sure the chick can't drown in the water dish. I also have mine in a "hospital" cage with one other chick for company, so the other peachicks don't bother it or keep it from eating.
There are some pretty good, step-by-step photos in this link that @casportpony gave us the other day:
Hope this helps! Send more photos if you can. Good luck