Medical Apparatus: Imaging Guide to Orthopedic Devices

Glossary: U - Z



Terms: Click below for the desired term





Medical Devices, Medical Procedures, and Foreign Bodies:
Abbreviations, Acronyms, and Definitions

by Tim B Hunter, MD, MSc and Mihra S. Taljanovic, MD, PhD



UAC  Umbilical artery catheter.

UDI. Unique device identifier. "FDA has established and continues to implement a unique device identification system to adequately identify medical devices through their distribution and use. When fully implemented, the label of most devices will include a unique device identifier (UDI) in human- and machine-readable form." (FDA, 2018).

UHMWPE.  Ultrahigh molecular weight polyethylene, a type of polyethylene popular for use as the bearing interface in total joint arthroplasty.

umbilical catheter.  A type of central venous catheter used in neonates. The catheter is inserted either into the umbilical vein or into one of the umbilical arteries.

Unicompartmental (knee arthroplasty, prosthesis, replacement).  A type of knee prosthesis that is limited to either the medial or lateral knee compartment.

Uni-Flate 1000.  A type of penile prosthesis.

unipolar (prosthesis).  A type of hip prosthesis in which the implant is a single metallic unit with the prosthetic head sized appropriately to press fit into the patient’s acetabulum.

universal rod. A type of spinal rod used with the modular spine fixation system.

UKA. Unicompartmental knee arthroplasty.

UKR. Unicompartment(al) knee replacement.

ureteral stent.  A urinary stent placed in the ureter.

urinary stent.  A generic term used for any stent employed in the urinary system to transverse benign and malignant strictures, bypass areas of dehiscence or obstructing calculi, and help with fistula healing.

UniSpacer (Unispacer). A cobalt-chrome self centering tibial hemiarthroplasty used in the treatment of isolated medial compartment osteoarthritis of the knee.

Urolume stent.  A metallic stent used for the treatment of urethral strictures. The stent is woven in the form of a tubular mesh composed of a superalloy (a high-temperature, high-stress alloy).

USPSTF. U,S, Preventive Services Taks Force: "The U.S. Preventive Services Task Force is an independent, volunteer panel of national experts in disease prevention and evidence-based medicine. The Task Force works to improve the health of people nationwide by making evidence-based recommendations about clinical preventive services."

UVC. Umbilical vein catheter.


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V & P.  Vagotomy and pyloroplasty.

VA. Veterans Administration, U.S. Department of Veterans Affairs. In the proper context VA can also mean vetebral augmentation (vertebroplasty or kyphoplasty).

V.A.C. Therapy. A therapy system of Kinetic Concepts, Inc., Austin, TX (KCI) that promotes wound healing through negative pressure (vacuum) suction at the wound surface to draw wound edges together, remove infectious materials, and actively promote granulation tissue formation. More commonly, this system and its wound drain which is directly placed over a wound, such as a diabetic foot ulcer, is known as a Wound Vac.

VAD.  See ventricular assist device. (Also sometimes known as LVAD [left ventricular assist device].)

van  Sonnenberg catheter.  A sump drainage catheter system developed  for the percutaneous treatment of abscesses.

VAERS. Vaccine Adverse Event Reporting System.

Vasport.  A type of vascular access port.

VCE. Video capsule endoscopy (also known as capsule endoscopy), a wireless video endscopic capsule which passes through the bowel to investigate small bowel pathology, particularly obscure gastrointestinal bleeding and iron deficiency anemia.

Vena Tech filter.  A type of inferior vena cava filter used to prevent clot propagation to the lungs.

veneer (dental). A layer of material placed over a tooth to improve its aesthetics and/or to protect it from damage.

ventricular assist device (VAD).  A device used to assist the heart in its blood pumping function. VADs may be univentricular or biventricular. For example, the Novacor left ventricular assist device is an implantable electrically driven pump that takes blood through a Dacron conduit from the apex of the left ventricle and pumps it through another Dacron conduit to the aorta.

ventriculoperitoneal shunt.  A shunt system designed to reduce intracranial pressure and prevent the development of hydrocephalus. Cerebrospinal fluid is shunted from the ventricular system of the brain to the peritoneal cavity.

VEPTR. Vertical Expandable Prosthetic Titanium Rib (DePuy Synthes).

VERILAST hip technology. A product of Smith & Nephew for hip replacement. It is a prosthetic femoral head which combines Oxinium with XLPE.

Vertebral cage.  A device used to replace or support a vertebral body destroyed by tumor, infection, or trauma. These are also known as a titanium interbody spacer (TIS), because they are often made from titanium. A typical vertebral cage has a hollow, threaded cylindrical structure filled with bone graft, and it is fixed to vertebral end plates superiorly and inferiorly by teeth. There are many different designs, some of which are the Bagby and Kuslich (BAK) Cage, the Ray Threaded Fusion Cage (Ray-TFC), the Harms Cage, and the Brantigan Cage.

Vertebroplasty.  Percutaneous injection of methylmethacrylate or similar material into a vertebral body to provide pain relief from a vertebral lesion, such as a pathologic fracture of the vertebra or the collapse of the vertebra due to trauma or osteoporosis.

v.i. vide infra; Latin for “see below.

Vitallium. A registered  trademark of Howmedica Osteonics (Mahwah, NJ) for a cobalt-chromium molybdenum alloy used in a variety of prostheses and medical instruments.

Vitoss bone graft substitute. Vitoss bone graft substitute (Stryker) and related Vitoss products consist of bioactive glass particles used for filling bony voids in the skeletal system to facilitate bone healing and remodeling.

Vivacit-E (polyethylene bearing). A product of Zimmer Biomet using a highly cross-linked polyethylene blended with Vitamin-E as a joint bearing surface to improve its mechanical properties.

viz. videlicet; Latin for “namely.”

VME. Virtual monoenergetic imaging, a metal artifact reduction application for dual-source CT.

VMI. Virtual monoenergetic imaging reconstruction.

VOICE. Value of imaging through comparative effectiveness.

VP shunt. Ventriculoperitoneal shunt.

v.s. vide supra; Latin for “see above.”

vulcanization. The process of treating rubber, either crude of synthetic, or plastic chemically to give it useful properties. Traditionally, rubber has been treated with sulfur and heat.


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Wallis device (Zimmer Holdings). A lumbar interspinous distraction device designed to hold the lumbar spine in flexion to reduce the effects of position dependent intermittent spinal stenosis related claudication.

Wallstent. A type of self-expanding metallic stent.  It is composed of a wire mesh and is used to bypass biliary and vascular obstructions.

wax plombage (oleo plombage).  A treatment for tuberculosis in which wax was placed in the thoracic cavity to collapse and replace the affected lung.

WFME. World Federation for Medical Education.

WHO. World Health Organization.

Wiltse system.  An orthopedic spine-fixation system in which pedicle screws are connected to a rod by clamps.

WNL. Within normal limits.

w/o.  Without.

Wolff's Law. A theory developed by German anatomist and surgeon Julius Wolff (1836-1902). Bone in a healthy individual will adapt to the loads under which it is placed with remodeling over time to resist the loading.

Wound Vac. A common name for the wound therapy system of Kinetic Concepts, Inc., Austin, TX (KCI) or its equivalent that promotes wound healing through negative pressure (vacuum) suction at the wound surface to draw wound edges together, remove infectious materials, and actively promote granulation tissue formation. The system uses the concept of negative pressure wound therapy (NWPT).

wraparound (fold-in, foldover) artifact.  A type of magnetic resonance imaging artifact in which a portion of the image is folded over onto some other portion of the image.

Wrt. With respect to.

WYSIWYG.  What you see is what you get.

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xenograft.  Same as a heterograft.

XIP.  {Perform} x-ray study in plaster.

XLIF. Extreme lateral interbody fusion. A minimally invasive surgery performed through the side of the body to treat spinal disorders.

XLPE. Highly cross-linked plastic created by altering chemical bonds in polyethylene.

XOP. {Perform} x-ray study out of plaster.

X-Stop device (Medtronic). A lumbar interspinous distraction device designed to hold the lumbar spine in flexion to reduce the effects of position dependent intermittent spinal stenosis related claudication.



YAG (laser). Yttrium aluminum garnet (laser).

Yale brace.  A type of cervical spine brace.

Yasargil clip.  A type of clip for occluding a cerebral aneurysm.

yaw.  The angle between the long axis of a bullet and its path of flight. More generally, movement of a ship or aircraft about a vertical axis.



zero-profile spine fixation. Anterior spinal fixation using a low profile spacer anchored by fixation screws into vertebral bodies above and below the diskectomy level. Anterior cervical disk fusion (ACDF) and anterior lumbar interbody fusion (ALIF) is often performed using zero-profile systems.

Zickle (nail) device. Misspelling of Zickel.

Zickel (nail) device. A system designed for the stabilization of pathologic femur fractures and subtrochanteric hip fractures.  It consists of an intramedullary rod and triflanged femoral neck nail combination.

Ziegler catalyst. Anyone of a group of catalysts that produce stereospecific polymers. Common examples include titanium trichloride (TiCl3) and aluminum alkyl {Al(CH3)3}. Named for Carl Ziegler (1893-1973).

Zielke rod. A type of spine-fixation device in which a unilateral plate is affixed to the lateral portion of adjacent vertebral bodies by screws.

Zielke system. See Dwyer-Zielke system.

zipper artifact. A type of computed radiographic artifact caused by missing information being reflected in the image as a lucent vertical band.  Also refers to a type of magnetic resonance imaging artifact consisting of a prominent black-and-white stripe often in the center of the frequency-encoding or phase-encoding axis.

Z-stent. A generic term for a variety of metallic stents used to overcome areas of narrowing in such tubular structures as vessels, bile ducts, ureters, and the urethra.


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Tim Hunter

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