Modular ulnar head decoupling strength: a biomechanical study.

Purpose: Knowing the assembly and disassembly forces of modular ulnar head implants will be invaluable to the surgeon faced with the challenge of either revising or extracting the implant. Our goal in this study was to evaluate the decoupling strength of the modular ulnar head implant as a function of assembly impaction force for the 3 most commonly used combinations of modular ulnar head implants.

Methods: Assembly forces and axial decoupling strength for 3 combinations of modular ulnar head implants were measured on an Instron 4206 instrument.

External fixator clamp reuse degrades clamp mechanical performance.

Objective: To determine the effects of clamp reuse for the Kirschner-Ehmer (KE); Securos; and the IMEX-SK clamp.

Study Design: Experimental bench test of mechanical properties.

Methods: Specially designed fixtures were used to mechanically test 18 clamps of each type with respect to 6 mechanical variables: fixator pin slippage, connecting bar slippage, fixator pin rotation, connecting bar rotation, and clockwise and counterclockwise clamp-bolt axis pivot.

Modular ulnar head decoupling force: case report.

Cobalt-chrome modular distal ulnar head replacement arthroplasty is a surgical option to restore stability to the distal radioulnar joint rendered unstable by hemi-resection arthroplasty or a total resection arthroplasty. However, the revision of dislocated modular cobalt-chrome ulnar head implants may pose an important intraoperative challenge. The Morse-taper disassembly force of modular ulnar head implants is not available in the current published literature.

Isoelastic distal ulnar head prosthesis: an in vitro joint simulator study.

Purpose: A prosthetic ulnar head that matches the mechanical properties of the sigmoid notch of the radius may produce a superior clinical outcome. In this study, we investigated the feasibility of an ultrahigh-molecular-weight polyethylene (UHMWPE) ulnar head prosthesis as a bearing material and compared the tribology (wear properties) with that of a cobalt chrome (CoCr) distal ulnar replacement.

Methods: We compared the friction properties, termed lubricity of the UHMWPE ulnar head prosthesis and polished CoCr ulnar head in an in vitro joint simulator with physiologic saline maintained at body temperature.

Failure mode and bending moment of canine pancarpal arthrodesis constructs stabilized with two different implant systems.

Objective: To compare failure mode and bending moment of a canine pancarpal arthrodesis construct using either a 2.7 mm/3.5 mm hybrid dynamic compression plate (HDCP) or a 3.