Abstract
The Acetabulum – In primary total hip arthroplasty the choices between cemented and cementless acetabular reconstruction are relatively simple. For the vast majority of surgeons now in practice cementing acetabular components is a relatively little practiced skill. Difficulty in minimising blood at the interface, pressurisation of the cement and the inability to easily use modularity makes this a less attractive option for most surgeons. That is not to say that good results cannot be routinely achieved and that there is anything wrong with this approach. Cementless fixation of the acetabulum is also reliable. Current controversies remain in the realm of adjuvant fixation techniques (degree of press fit, screw usage and other adjuvant fixation techniques.) Poly wear and concern with backside wear and rigidity of modular polyethylene capture remain concerns. In the realm of revision, cementless fixation has become the standard method for most revision surgeons and is employed in over 90% of cases. Here, the use of screws is less controversial. Cement is used almost exclusively to fix components to anti-protrusion cages.
The Femur – Fixation of the femoral component remains more controversial. Cemented stems currently available employ a wide variety of design features and surface finishes, and controversy regarding appropriate design and surface finish is extensive. However, the development of a symmetric cement mantle about the entire stem is considered an essential feature of modern cement technique. Cementless fixation has been shown to be effective in multiple settings including the aged and in patients with avascular necrosis and with inflammatory arthritis. Designs including proximally coated, extensively coated, and hydroxyapatite coated in straight, tapered and anatomic stem designs have all demonstrated good intermediate term results. The most concerning issue is the migration of particulates about the effective joint space and most implants attempt to create an ingrowth seal about the proximal part of the stem to prevent egress of particulates more distally. While concern remains about long-term stress shielding of proximal bone, there is little in the way of clinical data to support these concerns. Some data indicate that tapered stems, proximally coated stems with distal fixation features and extensively coated stems are more reliable at preventing thigh pain but, this issue appears significantly less problematic now than it did a decade ago.
Revision components are largely cementless and extensively coated though there is good evidence that roughened surface tapered components can be effective in the revision setting and that stem modularity, while adding potential long-term problems, may allow for greater intraoperative adaptability.
The abstracts were prepared by Mrs Dorothy L. Granchi, Course Coordinator. Correspondence should be addressed to her at PMB 295, 8000 Plaza Boulevard, Mentor, Ohio 44060, USA.
