Resources · Glossary

The shared vocabulary of O&P

Plain-language definitions for the terms that appear across the CMG catalog, from alignment and check sockets to K-levels and volume management. Written for new staff, referral partners, and anyone onboarding into the profession.

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83 of 83 terms

A

Abduction: Movement of a limb away from the midline of the body; orthoses are sometimes designed to hold a joint in a set degree of abduction.
Adduction: Movement of a limb toward the midline of the body, the counterpart to abduction in describing joint position and alignment.
AFO (Ankle-Foot Orthosis): A brace spanning the ankle and foot that controls ankle motion and alignment, commonly used for foot drop, instability, or post-stroke gait support.
Alignment: The spatial relationship between prosthetic components and the user's anatomy; correct alignment distributes load comfortably and produces an efficient gait.

B

Bench Alignment: The initial component alignment set in the workshop using standard reference values, before the patient ever stands in the prosthesis.

C

Central Fabrication: Outsourced manufacture of custom devices by a specialized lab working from a clinician's cast, scan, or measurements.
Check Socket: A transparent diagnostic socket fitted before the definitive socket is fabricated, allowing the clinician to observe pressure distribution and refine fit.
Cosmesis: The external finishing of a prosthesis — shaping, skin tones, and covers — that gives the device a natural appearance.
Cranial Remolding Orthosis: A custom helmet that gently redirects skull growth in infants with positional plagiocephaly or related head-shape conditions.
CROW (Charcot Restraint Orthotic Walker): A rigid, custom boot-style orthosis that encloses the foot and ankle to offload and protect a Charcot foot.

D

Definitive Prosthesis: The long-term prosthesis delivered after residual limb volume stabilizes, replacing the preparatory or temporary device.
Diagnostic Socket: Another name for a check socket: a test socket used to validate fit and comfort before definitive fabrication.
Distal: Anatomical direction meaning farther from the center of the body; the distal end of a residual limb is its tip.
Donning / Doffing: Putting on (donning) and taking off (doffing) a prosthesis or orthosis; ease of donning is a major factor in device selection.
Dorsiflexion: Upward motion of the foot at the ankle, bringing the toes toward the shin; many AFOs assist dorsiflexion during swing phase.
Dynamic Alignment: Fine-tuning of prosthetic alignment performed while the patient walks, refining the bench settings against observed gait.

E

Elevated Vacuum: A suspension method that uses a pump to maintain negative pressure inside the socket, improving linkage and helping stabilize limb volume.
Endoskeletal: Prosthesis construction built around an internal pylon-and-component frame, usually finished with a cosmetic cover; the dominant modern approach.
Energy Return: The spring-like behavior of a carbon or composite foot that stores load at midstance and releases it at push-off.
Exoskeletal: Older prosthesis construction in which a rigid outer shell carries the load, with no internal modular frame.
Extra-Depth Shoe: Therapeutic footwear with added internal volume to accommodate custom inserts, deformity, or dressings without pressure points.

F

Foot Shell: The cosmetic outer covering of a prosthetic foot that protects the keel and gives the foot a natural shape inside a shoe.

G

Gait Deviation: Any departure from a typical walking pattern — such as vaulting, circumduction, or lateral trunk lean — often signaling a fit or alignment issue.
Gait Training: Structured therapy that teaches a prosthesis or orthosis user safe, efficient walking patterns with their device.

H

HCPCS: The Healthcare Common Procedure Coding System, whose L-code section describes orthotic and prosthetic devices and services for billing.

I

Ischial Containment Socket: A transfemoral socket design that captures the ischium for skeletal stability and rotational control, succeeding the quadrilateral design for most users.

K

K-Level: Medicare's five functional classification levels (K0–K4) describing an amputee's mobility potential; component coverage is tied to the assigned level.
KAFO (Knee-Ankle-Foot Orthosis): A long-leg brace spanning the knee, ankle, and foot, used when the knee itself requires external control or support.
Knee Disarticulation: Amputation through the knee joint itself, preserving the full femur and offering end-bearing potential in socket design.

L

L-Code: An HCPCS code beginning with 'L' that identifies a specific orthotic or prosthetic device, addition, or service for claims and documentation.
Lanyard Suspension: A suspension method in which a strap attached to the liner is drawn through the socket and secured, simplifying donning for some users.
Last: The foot-shaped form a shoe is built around; therapeutic footwear uses lasts engineered for depth, width, and pressure distribution.
Liner: A cushioning gel or silicone interface worn over the residual limb that protects skin and often participates in suspension.
Locking Pin: A serrated pin at the distal end of a locking liner that engages a shuttle lock in the socket to suspend the prosthesis.
LSO (Lumbo-Sacral Orthosis): A spinal orthosis supporting the lumbar spine and sacrum, used for pain management, post-surgical protection, or stable fracture care.

M

Metatarsal Pad: A contoured pad placed proximal to the metatarsal heads to redistribute forefoot pressure, common in diabetic insert work.
Microprocessor Knee: A prosthetic knee whose onboard sensors and processor adjust resistance in real time, improving stability on stairs, slopes, and uneven ground.
Multiaxial Foot: A prosthetic foot that allows motion in several planes, helping the user adapt to uneven terrain.
Myoelectric: Control technology that reads electrical signals from residual muscles to drive a powered prosthetic hand, wrist, or elbow.

N

Negative Cast: The plaster or fiberglass impression taken directly off the patient's limb, from which a positive model is made.
Night Splint: An orthosis worn during sleep to hold a joint in a therapeutic position, commonly used for plantar fasciitis or contracture management.
NPI: The National Provider Identifier, a ten-digit number identifying healthcare providers; CMG uses it during business account verification.

O

Off-the-Shelf: A device prefabricated in standard sizes requiring minimal adjustment at fitting, as opposed to custom-fabricated or custom-fitted devices.
Orthosis: An external device applied to the body to support, align, correct, or improve the function of a body segment; the plural is orthoses.
Orthotist: A certified clinician who evaluates patients and designs, fits, and adjusts orthoses.

P

Partial Foot Prosthesis: A device restoring length and lever arm after amputation of part of the foot, ranging from toe fillers to rigid-plate designs.
Pistoning: Unwanted vertical movement of the residual limb inside the socket during gait, a classic sign of inadequate suspension or volume loss.
Plantarflexion: Downward motion of the foot at the ankle, pointing the toes; controlled plantarflexion at heel strike smooths loading response.
Ply: The thickness rating of a prosthetic sock; users add or remove plies through the day to manage limb volume changes inside the socket.
Positive Model: The plaster or digital model of the limb created from the negative cast or scan, modified by the clinician and used to form the device.
Prosthesis: A device that replaces a missing body part; in limb care, an assembly of socket, components, and interface tailored to the individual user.
Prosthetic Sock: A knitted sock worn over the residual limb or liner to fine-tune socket fit as limb volume fluctuates.
Prosthetist: A certified clinician who evaluates amputees and designs, fits, and aligns prostheses.
Proximal: Anatomical direction meaning closer to the center of the body; the proximal brim of a socket is its upper edge.
PTB (Patellar Tendon Bearing): A transtibial socket philosophy that concentrates load on pressure-tolerant areas, especially the patellar tendon.
Pylon: The structural tube connecting the socket to the foot in an endoskeletal prosthesis, available in aluminum, titanium, and carbon.

R

Residual Limb: The portion of the limb remaining after amputation, around which socket fit, suspension, and volume management revolve.
Rotator: A component that permits controlled axial rotation of the prosthesis, easing tasks like getting in and out of cars or sitting cross-legged.

S

SACH Foot: Solid Ankle Cushion Heel — a simple, durable prosthetic foot whose compressible heel substitutes for ankle motion; a longtime K1–K2 standard.
Sheath: A thin interface sock worn directly against the skin under socks or liners to reduce friction and wick moisture.
Shrinker: A graduated compression garment worn over the residual limb to control edema and shape the limb before and between fittings.
Shuttle Lock: The socket-mounted mechanism that captures a locking liner's pin, providing mechanical suspension with an audible click.
SMO (Supramalleolar Orthosis): A low-profile orthosis ending just above the ankle bones, used mostly in pediatrics to stabilize the hindfoot without limiting ankle motion.
Socket: The custom-shaped interface that contains the residual limb and transfers load between user and prosthesis; the part everything else depends on.
Socket Flexion: The built-in flexion angle of a transfemoral or transtibial socket relative to vertical, set to position muscles for efficient gait.
Stance Control Orthosis: A KAFO whose knee joint locks during stance for support yet releases during swing, allowing a more natural gait than a locked knee.
Stance Phase: The portion of the gait cycle when the foot is on the ground, bearing weight — roughly sixty percent of each stride.
Suction Suspension: Suspension achieved by maintaining negative pressure between limb (or liner) and socket, typically through a one-way valve.
Suspension: Whatever holds the prosthesis onto the body — pin locks, suction, vacuum, lanyards, sleeves, or anatomical contours.
Suspension Sleeve: An elastomeric sleeve rolled over the socket brim onto the thigh to seal or secure a transtibial prosthesis.
Swing Phase: The portion of the gait cycle when the foot is off the ground advancing forward; prosthetic knees are tuned for its timing.

T

Terminal Device: The functional end of an upper-limb prosthesis — a hook, hand, or task-specific tool, body-powered or externally powered.
TLSO (Thoraco-Lumbo-Sacral Orthosis): A spinal orthosis extending from below the collarbones to the pelvis, used for scoliosis management, fracture care, or post-surgical support.
Total Surface Bearing: A transtibial socket philosophy that distributes load evenly across the whole limb surface rather than concentrating it on tolerant zones.
Transfemoral: Above-knee: describing an amputation level through the femur, or the prosthesis built for it.
Transhumeral: Above-elbow: describing an amputation level through the humerus, or the prosthesis built for it.
Transradial: Below-elbow: describing an amputation level through the radius and ulna, or the prosthesis built for it.
Transtibial: Below-knee: describing an amputation level through the tibia and fibula, or the prosthesis built for it.
Trim Lines: The cut edges of a socket or orthosis; raising or lowering trim lines changes stiffness, control, and range of motion.

U

UCBL: A rigid foot orthosis with deep heel cup and high trim lines, named for the University of California Biomechanics Laboratory, used to control flexible hindfoot deformity.

V

Valgus: Angulation of a body segment away from the midline — as in knee valgus ('knock-knee') — which orthoses may correct or accommodate.
Varus: Angulation of a body segment toward the midline — as in knee varus ('bow-leg') — the counterpart of valgus.
Volume Management: The daily practice of compensating for residual limb volume change using sock plies, adjustable sockets, or vacuum so socket fit stays safe and comfortable.