Innovation and Technology Give Ankle Implants Resurgence

Total knee and hip replacement implants have beenrheumatoid arthritis. The advantage of the mobile
used with success for years, but ankle implants havebearing system is the third component, made of
had a long history of failure. In the late '70s and earlypolyethylene, a medical grade plastic. This insert
'80s the ankle implants wore out, popped out orallows for translation and rotation and decreases
collapsed into the bone. Ankle implant surgeryexcess shearing and breakdown of the polyethylene,
disappeared, for the most part, for almost twocommon in the two-component systems. Excess
decades, with surgeons recommending an ankleshear and stress on the interface between the metal
fusion for those patients with severe pain andcomponent and the bone can lead to implant failure.
disability due to ankle arthritis. In the earlier part ofSmall Bone Innovations, Inc. (SBi) notes that the
this decade, ankle implants have started to make aS.T.A.R. ® Ankle has been in development for 30
resurgence with the new emerging technology.years and the most recent design has been
Why the failures? Early ankle replacement devicesimplanted in over 15,200 patients around the world.
were fixed to the bone with cement. The fixationThere have been thirty-five peer-reviewed outcomes
was lost with the excess shearing forces causing thepapers published on the S.T.A.R. ® Ankle
bone support to fail. Compared with the hip and kneereplacement device.
joints, the ankle joint has a much smaller surface withIn August of 2000, a U.S. IDE Trial of S.T.A.R.®
much greater weight to support and greater shearingwas initiated to evaluate and safety and
forces.effectiveness of the device. The 2 year, prospective,
An ankle fusion, the current standard of care formulti-center controlled study evaluated 670 patients
surgical treatment of chronic ankle pain due toand compared the S.T.A.R. implant to joint fusion
arthritis, is limiting because of the lack of motion atsurgery. The results showed superior efficacy and
the ankle after the procedure. The newer anklesafety with the S.T.A.R. ® Ankle compared to
implant devices have higher success rates than theankle fusion.
older models. There are many two componentThe Scandinavian Total Ankle Replacement (S.T.A.R.)
implants on the market and currently being used,system is a 3- component, mobile bearing device,
including the Inbone Total Ankle Replacement (Wrightapproved for use without cement. The first
Medical Technology), Agility Total Ankle Systemcomponent is designed to fit into the tibia, the
(DePuy), the Eclipse Total Ankle Implantbottom portion of the shin bone. The second
(Kinetikos Medical, Inc.) and the Salto-Talaris Totalcomponent is designed to fit on the talus, also known
Ankle Prosthesis (Tornier).as the ankle bone. The third component is called the
Mobile bearing, three component ankle replacementUHMWPE Sliding Core, the mobile bearing made of
systems have been under review and in clinical trials.medical grade plastic. The Sliding Core is designed to
Entering the market, but still under review, are themove between the two metal components, to
Buechel-Pappas Ultra Total Ankle Replacementsimulate normal ankle joint motion.
(Endotec) and Hintegra Total Ankle ReplacementIndications for ankle joint replacement systems
(Integra). The S.T.A.R. (Small Bone Innovations, Inc)include severe pain and loss of mobility and function
total ankle replacement system was approved bydue to post traumatic arthritis, ankle osteoarthritis
the FDA in May, 2009, for ankle joint replacementand rheumatoid arthritis.
due to osteoarthritis, post-traumatic arthritis or