New type of hip arthroplasty failure related to modular femoral components: Breakage at the neck-stem junction

Abstract

Total hip replacements (THR) with modular femoral components (stem-neck interface) make it possible to adapt to extramedullary femoral parameters (anteversion, offset, and length) theoretically improving muscle function and stability. Nevertheless, adding a new interface has its disadvantages: reduced mechanical resistance, fretting corrosion and material fatigue fracture. We report the case of a femoral stem fracture of the female part of the component where the modular morse taper of the neck is inserted. An extended trochanteric osteotomy was necessary during revision surgery because the femoral stump could not be grasped for extraction, so that a long stem had to be used. In this case, the patient had the usual risk factors for modular neck failure: he was an active overweight male patient with a long varus neck. This report shows that the female part of the stem of a small femoral component may also be at increased failure risk and should be added to the list of risk factors. To our knowledge, this is the first reported case of this type of failure.

Fracture of the cobalt-chromium modular femoral neck component in total hip arthroplasty

“…Subsequently, many cases of modular titanium neck fracture were published [3][4][5]8,[10][11][12]. Most of them occurred in active and/or obese patients who had the ProfemurZ implant, which is the most widely used hip prosthesis with cervico-metaphyseal modularity in the USA.…”

“…Modularity provides greater versatility for matching the prosthetic hip to the native bone and joint geometry in terms of length, anteversion, and femoral offset [2]. However, modular THPs have been incriminated in a long list of complications including corrosion, pseudotumours, disassembly and, most notably, fracture of the removable-neck [3][4][5][6][7][8][9][10][11][12]. Most of the reported fractures occurred with titanium-alloy (Ti-6Al-4 V) necks.…”

High Risk of Failure With Bimodular Femoral Components in THA

“…Because of a substantial rate of loosening by subsidence with the bimodular PROFEMUR 1 E, in 2006 the bimodular PROFEMUR 1 Z stem was chosen for use. Because of reports of fracture of the bimodular neck, use of PROFEMUR 1 stems that accommodated the bimodular neck was abandoned [5,7,13,16,28,32,33]. Bearing surface…”

Stem-Sleeve Junction Failure of a Modular Femoral Hip System: A Retrieval Analysis

“…Improving the modular taper junction is crucial to preventing micromotion at the stem-sleeve interface that accelerates fretting corrosion mechanisms that can weaken the femoral stem causing subsequent implant failure. It is commonly known that perfect drying of the tapered surfaces before assembly is recommended to limit the risk of fretting and corrosion [42]. The present report is based on a detailed retrieval analysis.…”