Every Prosthetic Socket Type Explained

PTB, TSB, quad, IC, sub-ischial, pin lock, seal-in, vacuum. Every prosthetic socket is really answering 3 questions: where your weight goes (the shape), how it stays on (the suspension), and what it's made of (the construction). BELOW THE KNEE. The PTB (patellar tendon bearing) socket came out of the University of California in the late 1950s. It loads the patellar tendon and the inner flare of the shin bone and keeps pressure off the end of the bone. The "restricts blood flow" reputation comes from the old thigh cuff. TSB (total surface bearing) spreads the load over the whole limb, usually with a gel or silicone liner. A large review found active, younger and trauma amputees did better in TSB, but TSB was mostly tested with gel liners and PTB with foam, so shape and liner can't be fully separated. Hydrostatic sockets are cast under even pressure. ABOVE THE KNEE. The quad socket (1950s) gives the sitting bone a flat seat. The ischial containment (IC) socket, from the 1980s, wraps around the sitting bone and part of the pelvis; it is the most common today, but a 2021 review found it has not been proven better than the quad. The Marlo Anatomical Socket (MAS) contains the pelvic bone more closely and cuts the front and back lower. Sub-ischial sockets such as the NU-FlexSIV stop below the sitting bone; in a randomized trial they were more comfortable than IC, but a 2025 review rated the certainty that they are better as very low. HOW IT STAYS ON. Straps and belts, sleeves (since 1968), and liners with a pin lock, a lanyard or suction. Elevated vacuum had the least movement inside the socket in a 2019 clinical guideline, but it needs more attention and maintenance. WHAT IT'S MADE OF. Laminated carbon or resin shells, flexible inner sockets in a rigid frame (Össur Kristinsson, 1983), clear check sockets, early 3D-printed sockets, and adjustable sockets. In a 2026 trial of 3 commercial above-knee adjustable sockets, people gave up on a quarter of the LIM Infinite Sockets and 41% of the CJ Sails while getting used to them. HOW MANY. Several sockets in the first year is common while the limb shrinks. A 10-year UK study found established users needed about 3 new sockets per decade. A textbook rule of thumb: at about 10 plies of socks, it's time to talk about a new socket. The 3D limb and the illustrated hip are drawn to show the idea, not measurements. This video is information, not medical advice. Your prosthetist is the person to ask about your own fit. SOURCES. Atlas of Limb Prosthetics, ch. 4, 18B, 20B; Wilson 1969; Radcliffe 1955; Stevens et al., transtibial clinical practice guideline, 2019; Safari & Meier, systematic review, 2015; Brodie et al., 2021; Fatone & Caldwell, NU-FlexSIV technique, 2017; Fatone et al., randomized trial, 2021-2022; Bevacqua et al., 2025; Board et al., 2001; Kim et al., 3D-printed sockets review, 2022; Baldock et al., 2023; Gates et al., Arch Phys Med Rehabil 2026; Nair et al., 2008; Gholizadeh et al., 2012. LINKS. LIM Innovations Infinite Socket: https://www.liminnovations.com/ CJ Socket (the Sail): https://www.cjsocket.com/activfit-pro... Quorum Prosthetics Quatro Socket: https://www.quorumprosthetics.com/qua... NU-FlexSIV technique (Northwestern University): https://pubmed.ncbi.nlm.nih.gov/28094... Össur Iceross Seal-In X liner: https://www.ossur.com/en-us/prostheti... isbrave guide, prosthetic sockets explained: https://isbrave.com/guides/prosthetic... isbrave guide, vacuum sockets: https://isbrave.com/guides/vacuum-soc... isbrave guide, flexible inner sockets: https://isbrave.com/guides/flexible-i... FOOTAGE. All footage is real and credited on screen: AmputeeOT, BioApps Sdn Bhd, Bulow Orthotic & Prosthetic Solutions, Del Bianco Prosthetics, Govind Verma, Jeremy Warriner (Walking Spirit), Leimkuehler Orthotic-Prosthetic Center, LIM Innovations, Martin Bionics, Mary Free Bed Rehabilitation Hospital, Mission Gait, OrthoPro Twin Falls, Ottobock, Ottobock India, Ottobock Professionals, Össur, Prisma Health, Quorum Prosthetics, Sky Orthotics & Prosthetics, Stokosa Prosthetic Clinic, Summit City Prosthetics & Orthotics, The Leg Lady, Vessl Prosthetics, Vivid Frames Media. The 3D limb, the hip illustration and the stickers are illustrations. If you own any footage here and would like it removed, contact us and it comes down. Chapters 0:00 Why sockets get confusing 0:35 The 3 questions every socket answers 0:55 Below the knee, PTB 2:45 TSB 3:23 Hydrostatic 3:46 Above the knee, quad 4:27 Ischial containment (IC) 5:06 MAS 5:27 Sub-ischial (NU-FlexSIV) 6:06 How it stays on, straps to vacuum 7:45 What it's made of 8:45 Adjustable sockets 9:25 How many sockets you'll need #isbrave #prosthetics #prostheticsocket #amputee #limbloss #prostheticleg #aboveknee