Modular Interfaces
Modularity is defined as the ability to combine variable components of an implant in order to accommodate clinical hip, knee, or shoulder cases where standard monoblock designs may not offer optimum outcomes. Modular designs have been used for decades in
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George C. Babis and Vasileios I. Sakellariou
Introduction Modularity is defined as the ability to combine variable components of an implant in order to accommodate clinical hip, knee, or shoulder cases where standard monoblock designs may not offer optimum outcomes [1]. Modular designs have been used for decades in adult reconstruction surgery [1]. However, recent innovations, such as a second neck-stem taper junction in hip implants (Fig. 18.1) or multi-modular revision implants for hip (Fig. 18.2), knees, and shoulder cases, have been presented and favored in clinical use for their advantages in facilitating the anatomic restoration of the defective joints [2]. Intraoperative adjustment of limb length, headneck angle, neck-shaft version in hip and shoulder cases, and accurate reestablishment of joint line in knee arthroplasties, all provide flexibility and a variety of available options [2–6].
However, new problems have also arisen from the presence of additional metal interfaces. Catastrophic fractures at the junction sites, cold, welding, corrosion and fretting as well as the
G.C. Babis, MD, DSc (*) First Department of Orthopaedic Surgery, University of Athens, Attikon University General Hospital, Chaidari, Attica, Greece First Department of Orthopaedics, Attikon University Hospital, University of Athens Medical School, 1 Rimini Street, 12462 Chaidari, Attica, Greece e-mail: [email protected] V.I. Sakellariou, MD, DSc First Department of Orthopaedic Surgery, University of Athens, Attikon University General Hospital, Chaidari, Attica, Greece
Fig. 18.1 Neck-stem modularity. A variety of necks facilitates leg length and joint stability
T. Karachalios (ed.), Bone-Implant Interface in Orthopedic Surgery, DOI 10.1007/978-1-4471-5409-9_18, © Springer-Verlag London 2014
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G.C. Babis and V.I. Sakellariou
Total Hip Replacement Acetabular Components
Fig. 18.2 A modern modular revision femoral stem is shown
clinical implications of early implant loosening, and systemic immune reactions have been noted [2, 7–10]. With regard to the above statements and concerns, we present in this chapter up-to-date experimental and clinical data about the use of modular implants in hip, knee, and shoulder arthroplasties. We show the advantages and disadvantages associated with their use and known future directions.
Modular acetabular components have a history of almost 30 years [1]. Although clinical reports did not show a clear advantage of the primary cemented modular over monoblock implants in terms of longevity and loosening, their ability to replace the liner without disrupting the prosthesisbone interface in future procedures has been a significant evolution in implant design [1]. New cementless metal-backed implant designs with different surface porous coatings have been used, showing at least an outcome equal to that of cemented cups, while in revision cases modular implants have outperformed monoblock-cemented components [11–13]. The major advantage of modular metal-backed acetabular components lies in
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