Search

Despite advances in care, infection in total joint arthroplasty remains a serious problem that has yet to be solved. Reported infection rates range from

Modular necks are a relatively new innovation in total hip arthroplasty (THA), with several companies now offering modular neck options. The proposed advantages of reduced impingement, reduced dislocation rate, and better reconstitution of leg length and offset are compelling. However, few reports in the literature address the outcomes of these devices, and those that are published at best demonstrate equivalence to conventional THA. There are numerous disadvantages to this new technology. Neck dissociation has been reported with a specific design of the modular taper. Numerous case reports exist of the fracture of titanium modular femoral necks, with 1 large series of 5000 cases reporting a fracture rate of 1.4%. Fractures occurred more frequently in heavy men (>100 kg), with the preponderance of fractures occurring around the 2-year mark. Retrieval analysis demonstrates failure of the titanium components at the Morse taper junction of the neck and femoral stem at the point of maximal tension, likely related to notch sensitivity. The additional interface of modular necks in the effective joint space has the potential to generate significant metal ions through a pitting corrosion process. Evidence exists of highly elevated serum cobalt and chromium ions in a modular junction used in large-head THA supporting these concerns. The use of particular neck geometries, such as long retroverted necks, may adversely affect the local biomechanical forces on the femoral component. The proposed mechanism is an increased lever arm leading to increased torque on stair climbing or rising from a chair. Finally, modular necks add significant costs to the implant and the health care system. On balance, based on the literature, the proximal modular neck in THA is a bridge too far.

The use of antibiotic bone cement in total hip arthroplasty (THA) is the standard of care in countries with long-standing national registries, as data from the registries demonstrates an improvement in survivorship by reducing the incidence of both septic and aseptic failures. There is reluctance in North America to embrace antibiotic bone cement, although the percentage of use is increasing. Reasons cited for not using antibiotic cement include lack of efficacy, adverse effects on mechanical properties, increased costs, bacterial resistance, and systemic toxicity. Little to no compelling data in the literature support these claims, and significant evidence refutes them, specifically: registry data and randomized controlled trials demonstrate a clear reduction in deep joint infections with the use of antibiotic bone cement; antibiotic bone cement has lower incidence of both septic and aseptic loosening, indicating no negative effect on mechanical properties; antibiotic bone cement is cost-effective, given its proven ability to reduce revision rates and prevent poor patient outcomes; there is no evidence to support bacterial resistance, and antibiotic bone cement may reduce the incidence of resistance; and there are no reported cases of systemic toxicity from manufacturer-prepared antibiotic cement in primary THA or total knee arthroplasty. Based on the strong evidence supporting the benefits of antibiotic bone cement and the lack of evidence against its use, it is difficult to justify why antibiotic cement is not the standard of care for primary cemented THA in North America.

European nations, especially Scandinavian countries, have used cemented fixation since the introduction of total hip arthroplasty. In Sweden, with arguably the best national-level data on prostheses survivorship, >90% of all stems are fixated with cement. In sharp contrast, it is estimated that in the United States, >88% of all femoral stems use cementless technology. This represents a diametrically opposed difference in philosophical approach: the so-called North Atlantic Divide. The departure in North America from cemented femoral stems can be traced to the coinage of the phrase "cement disease," which implicated cement as a leading cause of osteolysis. This led to prolific innovation of uncemented technologies in North America, while European countries favored standardization enabled by the national arthroplasty registries. The term "cement disease" has been proven to be a misnomer, as supported by excellent outcomes from the Scandinavian registries, as well as excellent long-term outcomes for cemented stems in United States series, even in patients younger than 50 years. Like uncemented stems, there is variability in survivorship between femoral stems, and this appears to be related to specific design features. Despite the excellent long-term results, the use of cemented femoral components in Europe and Canada is decreasing in favor of uncemented stems. The reasons for this are not immediately obvious.