Current concepts and outcomes in cemented femoral stem design and cementation techniques: the argument for a new classification system

Abstract

Cemented implant fixation design principles have evolved since the 1950s, and various femoral stem designs are currently in use to provide a stable construct between the implant–cement and cement–bone interfaces. Cemented stems have classically been classified into two broad categories: taper slip or force closed, and composite beams or shaped closed designs. While these simplifications are acceptable general categories, there are other important surgical details that need to be taken into consideration such as different broaching techniques, cementing techniques and mantle thickness. With the evolution of cemented implants, the introduction of newer implants which have hybrid properties, and the use of different broaching techniques, the classification of a very heterogenous group of implants into simple binary categories becomes increasingly difficult. A more comprehensive classification system would aid in comparison of results and better understanding of the implants’ biomechanics. We review these differing stem designs, their respective cementing techniques and geometries. We then propose a simple four-part classification system and summarize the long-term outcomes and international registry data for each respective type of cemented prosthesis. Cite this article: EFORT Open Rev 2020;5:241-252. DOI: 10.1302/2058-5241.5.190034

Early failure of an uncemented femoral stem, as compared to two other stems with similar design, following primary total hip arthroplasty performed with direct anterior approach

“…All failed implants were revised using a cemented, standard Exeter and published data show no difference in the risk of second revision between cementless and cemented techniques providing there is no significant proximal bone loss and appropriate stem designs with modern cementing technique are used. 31,32 In our department, we favour contemporary distal bearing cementless femoral implants for revision surgery. However, the insertion of these implants through an anterior approach poses technical problems with the risk of intraoperative fractures possible.…”

Femoral Stem Cementation in Primary Total Hip Arthroplasty

“…They found that reaming to the size of the prosthesis resulted in better outcomes, with comparable long-term survival, and significantly less radiolucent lines. Such results challenge conventional wisdom on cement mantle thickness 76,99,108,111 . Although a mantle of .2 mm is still preferred by most surgeons, good outcomes have been demonstrated with thinner mantles with specific stem designs and techniques.…”

“…Cassar-Gheiti et al sought to expand on this dichotomous classification scheme by accounting for other designs (Table II) 76 . In their four-type classification system, they introduced a type 3 implant that achieves a composite beam effect with a self-centering, press-fit design.…”

Comparison of periprosthetic femoral fracture torque and strain pattern of three types of femoral components in experimental model

“…Implants. We used three types of stems based on the new classification of cement stems described by Cassar-Gheiti et al 9 (Figure 1). The CPT stem (Zimmer Biomet) is also known as a taper-slip or force-close stem.…”