Biomedical subjects

T E McIff

Publications and source records attributed to T E McIff.

3 recordsLinked to original sources

PubMed2005

The effect of accuracy of implantation on range of movement of the Scandinavian Total Ankle Replacement.

When performing the Scandinavian Total Ankle Replacement (STAR), the positioning of the talar component and the selection of mobile-bearing thickness are critical. A biomechanical experiment was undertaken to establish the effects of these variables on the range of movement (ROM) of the ankle. Six cadaver ankles containing a specially-modified STAR prosthesis were subjected to ROM determination, under weight-bearing conditions, while monitoring the strain in the peri-ankle ligaments. Each specimen was tested with the talar component positions in neutral, as well as 3 and 6 mm of anterior and posterior displacement. The sequence was repeated with an anatomical bearing thickness, as well as at 2 mm reduced and increased thicknesses. The movement limits were defined as 10% strain in any ligament, bearing lift-off from the talar component or limitations of the hardware. Both anterior talar component displacement and bearing thickness reduction caused a decrease in plantar flexion, which was associated with bearing lift-off. With increased bearing thickness, posterior displacement of the talar component decreased plantar flexion, whereas anterior displacement decreased dorsiflexion.

Aged↗

PubMed2004

The effect of agility ankle prosthesis misalignment on the peri-ankle ligaments.

In the Agility total ankle replacement system, motion is constrained by the implant's articulating surfaces and the peri-ankle ligaments. The effects of plausibly occurring implant malpositioning on peri-ankle ligament functional extension during walking were explored in this study. The intent was to determine whether certain ligaments could serve as guides to assist in proper component positioning at implantation. Using a cadaver preparation with simulated physiologic motion and loading, we monitored change of ligament length of the anterior talofibular, posterior talofibular, calcaneofibular, and tibiocalcaneal ligaments resulting from controlled malpositioning of the tibial component relative to a neutral position. During a simulated walking cycle, effects of mediolateral and anterior/posterior translation, internal and external rotation, inversion and eversion, and elevation of the component were evaluated. In all cases, tibial component displacement from the neutral position caused atypical length change in one or more of the peri-ankle ligaments. In particular, anterior/posterior displacement significantly changed the lengthening behavior of all four tested ligaments. The anterior talofibular ligament was sensitive to transverse plane displacements, whereas the tibiocalcaneal ligament was sensitive to coronal plane displacements. For the Agility prosthesis, these two ligaments seem to be sensitive guides for tibial component positioning at implantation.

Ankle Joint↗

PubMed2000

Total ankle replacement revisited.

The surgical treatment of painful, end-stage ankle arthritis includes ankle arthrodesis and total ankle replacement. In the past decade, total ankle replacement has become a viable alternative to ankle arthrodesis. Modern implant designs either involve a syndesmosis fusion and resurfacing of the medial and lateral recesses of the ankle joint or the use of a 3-component, mobile bearing implant. In limited clinical series, the early results of both these prosthetic design approaches are encouraging. In selected patients, ankle arthroplasty is an effective approach to relieving pain and improving function. The purposes of this paper are to review the clinical results from total ankle replacement and ankle arthrodesis; discuss indications, contraindications, design features, postoperative rehabilitation, and initial results for the major current total ankle designs; and present concepts for future total ankle development. In particular, this article explores the advantages and concerns with 2 prevalent but different design approaches. It also discusses future directions for total ankle replacement.

Ankle Joint↗