Acetabular cage - a device for acetabular revision that allows restoration of a proper center of rotation for the femoral head in cases where host bone is inadequate to support standard acetabular components; acetabular cages feature moldable tabs for fixation to available bone stock.
Articular function restoration - a primary objective of revision THA; successful restoration of articular function requires good approximation of the proximal anatomical frame so that joint motion mechanics and gait are preserved.
Aseptic loosening - loss of implant fixation attributed to osteolysis that is not associated with infection; most discussions of aseptic loosening are concerned with implant-generated debris.
Bone stock - bone that surrounds an implant and provides the interface for fixation and bony integration; the adequacy of a revision patient's available bone stock strongly influences a surgeon's operative decision-making.
Cerclage - wires, cables or bands used to prevent or manage fractures of the femur
Corrosion - chemical degradation of metallic components arising from usage environment; the inside of the body is considered a highly corrosive environment requiring material selections with high corrosion resistance; points of connection and/or wear between components or where dissimilar metals meet are particularly vulnerable to corrosion.
Corundum - a crystalline form of aluminum oxide used as the blasting media (grit) in the surface roughening of the Lima Revision stem components.
Distal Fixation - the means by which a revision stem often achieves stability; in primary THA, proximal fixation is typically preferred for stress-shielding avoidance, but in revision THA where proximal bone loss may be extensive, distal fixation is relied upon.
Drop forging - a manufacturing process for creating complex geometries with high strength where heat-softened metal is dropped into a tool or die and formed to shape under high pressure in the tool; the Lima Modular Revision Hip neck components are drop forged.
Fatigue - deterioration of a mechanical device that occurs with long-term cyclic loading; testing and design for withstanding fatigue is an important part of developing hip prostheses, and is particularly important for modular designs where connection points present vulnerabilities and where extreme combinations of components can compromise fatigue performance.
Flutes - fins or ridges that run along the length of the implant body.
Fretting - wear caused by micromotion at the connection between modular components; can result in fretting corrosion and metal ion release.
Heat treat - a processing step in a manufacturing process in which the metallurgy of a device is altered by exposure to heat; the Lima Revision stem components undergo heat treating that increases mechanical strength by 20%.
Lysis - the dissolution or destruction of cells due to biochemical processes; bone lysis (osteolysis) leads to loss of implant fixation necessitating revision; osteolysis can arise from wear debris, infection or metabolic processes.
Modularity - a design feature where components of various sizes can be fit together in a custom-fit manner.
Morse taper - a standardized geometry for mating parts commonly used in orthopedics for connecting modular heads, necks and stems.
On-growth - the means of bony integration of a cementless prosthesis with a roughened or blasted surface in lieu of a porous coating; where porous coatings contain void space that permits ingrowth, roughened surfaces are limited to ongrowth.
Primary fixation - the initial, mechanical stability of an uncemented orthopedic implant before biological incorporation has taken place.
Proximal anatomical frame - the morphology of the proximal femur (distances, angles and offsets) that creates proper mechanics for motion; reconstructing the proximal anatomical frame is an essential objective of total hip replacement, and achieving satisfactory restoration can be extremely challenging in revision THA.
Revision - repeat operation to replace a failed prosthesis or other surgical intervention deemed necessary by the surgeon.
Roughness - a surface's lack of smoothness assessed by measuring height changes (peaks and valleys) in the surface; orthopedic implants may be deliberately roughened to increase friction for primary fixation and to increase the surface area for bony integration via ongrowth; the Lima Revision stem has an average surface roughness of 3 to 4 microns.
Secondary fixation - long term fixation of an uncemented orthopedic implant via bony integration; when secondary fixation is achieved, forces are able to be transmitted from the implant to bone in a distributed manner (e.g. load sharing); secondary fixation is important to implant survivorship.
Ti6Al4V - a titanium alloy containing aluminum and vanadium commonly used in orthopedic implants; the Lima Modular Revision Hip components are made from Ti6Al4V. The proximal body locking screw also has an anti-rotation peg made of UHMWPE. The acetabular reconstruction cages are made of commercially pure titanium.
Transfemoral or Wagner approach - surgical access technique sometimes employed for hip stem revision when proximal femoral integrity is a concern; approach involves creating a longitudinal bone flap in the femur for accessing the distal reaches of the medullary canal; care must be taken to maintain muscular attachments to the bone flap intraoperatively, and the flap is closed around the revision stem with cerclage wire.
Tribology - the science and engineering of articulating surfaces with concern for wear, friction and lubrication; important in orthopedics for the study and design of articulating wear surfaces.
Wagner Stem - a type of revision stem featuring a cylindrical, tapered distal portion with longitudinal straight flutes for cortical fixation and rotational stability; the original Wagner stem made by Zimmer (Wagner SL) is a one-piece design; many modular devices are marketed with Wagner-style distal component.