Assessment of external fixator reusability using load- and cycle-dependent tests.

No standard method has been established for investigating repeated use of an external fixator. The purpose of the current study was to establish a fatigue testing method for assessing fixator frame reuse. A unilateral DynaFix trade mark external fixator system was tested using high-load and low-cycle (900-150 N at 5 Hz) and low-load and high-cycle (450-100 N at 10 Hz) tests (assumed one use of 500,000 and 1 million cycles, respectively).

Tibial interface wear in retrieved total knee components and correlations with modular insert motion.

Background: Wear occurring at the interface between the polyethylene insert and metal baseplate of a modular tibial component has become an increasingly common finding at the time of revision total knee arthroplasty. Although this so-called backside wear on retrieved polyethylene inserts has been evaluated in prior studies, wear on retrieved metal baseplates has not been described, to our knowledge. The purposes of the present study were to characterize backside wear on retrieved polyethylene inserts and on the mating surfaces of their corresponding baseplates and to investigate if there is a relationship between backside wear and relative motion of the modular elements.

In vivo deterioration of tibial baseplate locking mechanisms in contemporary modular total knee components.

Background: The results of recent studies documenting the backside wear of polyethylene inserts retrieved from total knee implants call into question the stability of the locking mechanisms of modular tibial components. Wear of the metal tibial baseplate suggests that the capture mechanisms of some modular fixed-bearing tibial components do not adequately restrict in vivo motion of the insert. The purposes of this study were (1) to present a method for evaluating locking-mechanism stability and (2) to investigate the stability of modular tibial components after an interval in vivo.

Comparison of two systems for tibial external fixation in rabbits.

Background And Purpose: Use of rabbits in orthopedic investigations is common. In this study, focus is on factors that influence bone healing and on distraction osteogenesis. Biomechanical characteristics of two external fixator systems (Orthofix device and Hoffmann device) for long bones were tested.