Periprosthetic joint infection (PJI) is one of the most dreaded complications after arthroplasty surgery; thus numerous approaches have been undertaken to equip metal surfaces with antibacterial properties. Due to its antimicrobial effects, silver is a promising coating for metallic surfaces, and several types of silver-coated arthroplasty implants are in clinical use today. However, silver can also exert toxic effects on eukaryotic cells both in the immediate vicinity of the coated implants and systemically. In most clinically-used implants, silver coatings are applied on bulk components that are not in direct contact with bone, such as in partial or total long bone arthroplasties used in tumour or complex revision surgery. These implants differ considerably in the coating method, total silver content, and silver release rates. Safety issues, such as the occurrence of argyria, have been a cause for concern, and the efficacy of silver coatings in terms of preventing PJI is also controversial. The application of silver coatings is uncommon on parts of implants intended for cementless fixation in host bone, but this option might be highly desirable since the modification of implant surfaces in order to improve osteoconductivity can also increase bacterial adhesion. Therefore, an optimal silver content that inhibits bacterial colonization while maintaining osteoconductivity is crucial if silver were to be applied as a coating on parts intended for bone contact. This review summarizes the different methods used to apply silver coatings to arthroplasty components, with a focus on the amount and duration of silver release from the different coatings; the available experience with silver-coated implants that are in clinical use today; and future strategies to balance the effects of silver on bacteria and eukaryotic cells, and to develop silver-coated titanium components suitable for bone ingrowth. Cite this article:
A modular femoral head–neck junction has practical
advantages in total hip replacement. Taper fretting and corrosion
have so far been an infrequent cause of revision. The role of design
and manufacturing variables continues to be debated. Over the past
decade several changes in technology and clinical practice might
result in an increase in clinically significant taper fretting and
corrosion. Those factors include an increased usage of large diameter
(36 mm) heads, reduced femoral neck and taper dimensions, greater
variability in taper assembly with smaller incision surgery, and
higher taper stresses due to increased patient weight and/or physical
activity. Additional studies are needed to determine the role of
taper assembly compared with design, manufacturing and other implant
variables. Cite this article:
Since 1996 more than one million metal-on-metal
articulations have been implanted worldwide. Adverse reactions to
metal debris are escalating. Here we present an algorithmic approach
to patient management. The general approach to all arthroplasty
patients returning for follow-up begins with a detailed history,
querying for pain, discomfort or compromise of function. Symptomatic
patients should be evaluated for intra-articular and extra-articular
causes of pain. In large head MoM arthroplasty, aseptic loosening
may be the source of pain and is frequently difficult to diagnose.
Sepsis should be ruled out as a source of pain. Plain radiographs
are evaluated to rule out loosening and osteolysis, and assess component
position. Laboratory evaluation commences with erythrocyte sedimentation
rate and C-reactive protein, which may be elevated. Serum metal
ions should be assessed by an approved facility. Aspiration, with
manual cell count and culture/sensitivity should be performed, with
cloudy to creamy fluid with predominance of monocytes often indicative
of failure. Imaging should include ultrasound or metal artifact
reduction sequence MRI, specifically evaluating for fluid collections
and/or masses about the hip. If adverse reaction to metal debris
is suspected then revision to metal or ceramic-on-polyethylene is indicated
and can be successful. Delay may be associated with extensive soft-tissue
damage and hence poor clinical outcome.
The management of bone loss in revision replacement of the knee remains a challenge despite an array of options available to the surgeon. Bone loss may occur as a result of the original disease, the design of the prosthesis, the mechanism of failure or technical error at initial surgery. The aim of revision surgery is to relieve pain and improve function while addressing the mechanism of failure in order to reconstruct a stable platform with transfer of load to the host bone. Methods of reconstruction include the use of cement, modular metal augmentation of prostheses, custom-made, tumour-type or hinged implants and bone grafting. The published results of the surgical techniques are summarised and a guide for the management of bone defects in revision surgery of the knee is presented.
Polymethylmethacrylate remains one of the most enduring materials in orthopaedic surgery. It has a central role in the success of total joint replacement and is also used in newer techniques such as percutaneous vertebroplasty and kyphoplasty. This article describes the current uses and limitations of polymethylmethacrylate in orthopaedic surgery. It focuses on its mechanical and chemical properties and links these to its clinical performance. The behaviour of antibiotic-loaded bone cement are discussed, together with areas of research that are now shedding light upon the behaviour of this unique biomaterial.
The long-term effects of metal-on-metal arthroplasty are currently under scrutiny because of the potential biological effects of metal wear debris. This review summarises data describing the release, dissemination, uptake, biological activity, and potential toxicity of metal wear debris released from alloys currently used in modern orthopaedics. The introduction of risk assessment for the evaluation of metal alloys and their use in arthroplasty patients is discussed and this should include potential harmful effects on immunity, reproduction, the kidney, developmental toxicity, the nervous system and carcinogenesis.
We undertook a review of the literature relating to the two basic stem designs in use in cemented hip replacement, namely loaded tapers or force-closed femoral stems, and the composite beam or shape-closed designs. The associated stem fixation theory as understood from It is clear that both design principles are capable of producing successful long-term results, providing that their specific requirements of stem metallurgy, shape and surface finish, preparation of the bone and handling of the cement are observed.
