Various of Cementless Acetabular Cups and Femoral Stems Utilized in Multiple Applications: A Review

Review Article

Austin J Musculoskelet Disord. 2019; 6(1): 1052.

Various of Cementless Acetabular Cups and Femoral Stems Utilized in Multiple Applications: A Review

Bernardino S*

Department of Orthopaedic and Trauma Surgery, ASL Bari Institution, Viale Regina Margherita, Altamura (Bari), Italy

*Corresponding author: Saccomanni Bernardino, Department of Orthopaedic and Trauma Surgery, ASL Bari Institution, Viale Regina Margherita, Altamura (Bari), Italy

Received: May 01, 2019; Accepted: May 28, 2019; Published: June 04, 2019


Today, the majority of cementless acetabular cups are hemispherical pressfit. Thus, acetabular cups without extruded liners with improved congruity are being widely introduced and have shown outstanding clinical outcomes. Various designs of cementless femoral stems were developed and utilized in multiple applications. These can be classified and subjected to direct comparisons based on their contact area and contact site between implants and cortical bones. Even though short femoral stems were introduced with several theoretical merits, enough follow-up results have not accumulated, and thus further studies are warranted. A clear understanding of fixation principles per different implant designs would be informative and helpful for selection of optimal implants for respective applications to patients.

Keywords: Hip Replacement Arthroplasty; Cementless; Implant Design


One of the most important factors in driving a successful cementless Total Hip Arthroplasty (THA) is achieving osteointegration between implant and bone. Although multiple factors impacting osteointegration, implant design, appropriate surface treatment, primary mechanical stability, and patient’s osteogenesis are the most critical [1]. In this review, the authors review fixation principles of respective cementless hip replacement implants and considerations for making an optimal selection.

Surface Treatment of Cementless Hip Replacement Implants

Osteointegration can be achieved by bone in-growth and bone on-growth. Bone in-growth indicates firm fixation between bone and metal through bone growth into the porous surface of metal implants. Meanwhile, bone on-growth is fixation between metal and bone via bone growth on the rough surface of an implant. Depending upon the surface treatment, mechanisms of biological fixation differ [2].

Design of Acetabular Cup

Acetabular cups can be classified as either cemented or cementless depending on the presence or absence of cement used during fixation. In this chapter, we discuss the design of surface-treated hemispherical press-fit acetabular cups, currently the most widely utilized cementless acetabular cups.

Surface-treated press-fit fixation cup

Press-fit fixation is a technique, which uses physical force on the substance to be inserted so that maximal press fit can be achieved by surrounding material. For this application, the size of press-fit fixation acetabular cups are generally 1-4 mm bigger than reaming diameter so that viscoelasticity of acetabulum maximizes the binding force of acetabular cups [3].

Theoretically, the press-fit method does not require additional fixation such as the use of screws since sufficient primary fixation can be achieved. However, additional screw fixation might be used in the certain cases if press-fit fixation is not satisfactory. Further, inexperienced orthopedic surgeons may judge the gap between acetabular bone and cup through screw holes thus, it is recommended to select a cup design with screw holes.

Evolution of cementless hemispherical acetabular cups

Cementless acetabular cups have evolved through three generations based on their development periods and design characteristics [4].

1st generation hemispherical acetabular cups: These acetabular cups were an early design developed in the 1980s. Extension of the polyethylene liner was designed to be extruded from the acetabular cup for assembly. However, extruded liners were easily damaged by impingement as liners were somewhat thin and fragile; this results in frequent damage of the locking mechanism and following liner dissociation. Further, congruity was not sufficient, and there often was a gap between liners and the inner surface of acetabular cups in which the back-side of liners was subjected to wear (Figure 1).