Is wear debris responsible for failure in alumina-on-alumina implants?

Alumina ceramic-on-ceramic hybrid total hip arthroplasty. A median of 15 years follow-up

INTRODUCTION

The optimum choice of bearing surfaces in total hip replacement (THR) in the younger and active patient remains controversial. The aim of this study was to report the 10 year clinical outcomes, and a median of 15 year implant survival and incidence of complications in a series of Alumina ceramic-on-ceramic THRs utilising an uncemented shell and cemented stem.

METHODS

From January 2004 to December 2007, 175 consecutive patients (195 hips) underwent primary THR. The acetabular components was Trident Peripheral Self Locking (Stryker Orthopaedics) with a third-generation ceramic head and liner (Alumina ceramic, Stryker Orthopaedics). The stem utilised was an Exeter V-40 (Stryker Orthopaedics). Data were collated on demographics, surgical factors, clinical outcomes, radiographic outcomes and revision.

RESULTS

23 patients (27 THRs) died during the follow-up period at a median of 7.8 (3.8 to 9.0) years post-operatively due to causes unrelated to the THR. Median age at time of surgery was 55 (interquartile range 48-60) years. Median follow-up for surviving patients was 15.2 years. Survivorship for all-cause revision was 97.2%. Increasing patient age at time of surgery was associated with a higher OHS at 10 years (p = 0.022). 32 mm head diameter had an improved OHS at 3 months (p = 0.014) and 10 years (p = 0.030). Posterior surgical approach had a statistically significant better OHS at 3 months (p = 0.015) and 1 year (p < 0.001), but the effect was not significant at 10 years (p = 0.440).

CONCLUSION

The findings of this study support excellent long-term outcomes and survivorship of Alumina ceramic-on-ceramic bearing in a hybrid THR in a younger population. Surgical factors leading to a more favourable outcome were the use of a 32 mm femoral head and a posterior approach. Increasing age at surgery demonstrated the most sustained improvement in 10 year clinical outcomes.

Diagnostic guidelines for the histological particle algorithm in the periprosthetic neo-synovial tissue

BACKGROUND

The identification of implant wear particles and non-implant related particles and the characterization of the inflammatory responses in the periprosthetic neo-synovial membrane, bone, and the synovial-like interface membrane (SLIM) play an important role for the evaluation of clinical outcome, correlation with radiological and implant retrieval studies, and understanding of the biological pathways contributing to implant failures in joint arthroplasty. The purpose of this study is to present a comprehensive histological particle algorithm (HPA) as a practical guide to particle identification at routine light microscopy examination.

METHODS

The cases used for particle analysis were selected retrospectively from the archives of two institutions and were representative of the implant wear and non-implant related particle spectrum. All particle categories were described according to their size, shape, colour and properties observed at light microscopy, under polarized light, and after histochemical stains when necessary. A unified range of particle size, defined as a measure of length only, is proposed for the wear particles with five classes for polyethylene (PE) particles and four classes for conventional and corrosion metallic particles and ceramic particles.

RESULTS

All implant wear and non-implant related particles were described and illustrated in detail by category. A particle scoring system for the periprosthetic tissue/SLIM is proposed as follows: 1) Wear particle identification at light microscopy with a two-step analysis at low (× 25, × 40, and × 100) and high magnification (× 200 and × 400); 2) Identification of the predominant wear particle type with size determination; 3) The presence of non-implant related endogenous and/or foreign particles. A guide for a comprehensive pathology report is also provided with sections for macroscopic and microscopic description, and diagnosis.

CONCLUSIONS

The HPA should be considered a standard for the histological analysis of periprosthetic neo-synovial membrane, bone, and SLIM. It provides a basic, standardized tool for the identification of implant wear and non-implant related particles at routine light microscopy examination and aims at reducing intra-observer and inter-observer variability to provide a common platform for multicentric implant retrieval/radiological/histological studies and valuable data for the risk assessment of implant performance for regional and national implant registries and government agencies.

Oscillatory device for use with linear tribometer, for tribological evaluation of biomaterials

Orthopedic implants still have limitations regarding their durability, despite being in use for over fifty years. Particles arising from wear due to the relative motion of their surfaces remain responsible for aseptic failure. This paper presents a device to be coupled with a reciprocal linear tribometer to reproduce the ex vivo wear of biomaterials, allowing the measurement of force and coefficient of friction. The device consists of a structure connected to the tribometer that transforms its reciprocal linear motion into one that is oscillatory for the mechanical assembly that contains the samples to test the desired biomaterials. The tribological pair used for testing consisted of Ultra High Molecular Weight Polyethylene (UHMWPE) in conjunction with the austenitic stainless steel AISI 316L in dry lubrication. The results showed that the values of the coefficient of friction in the linear mode and oscillatory mode and the UHMWPE life curve in the oscillatory mode were consistent with those cited in the literature for tests in a dry lubrication environment. Moreover, the UHMWPE sample life curve showed a reduction in the wear rate that can be explained by the preponderance of a wear mechanism over the others. The volumetric wear showed an increase with the number of cycles.

Biological response to prosthetic debris

Joint arthroplasty had revolutionized the outcome of orthopaedic surgery. Extensive and collaborative work of many innovator surgeons had led to the development of durable bearing surfaces, yet no single material is considered absolutely perfect. Generation of wear debris from any part of the prosthesis is unavoidable. Implant loosening secondary to osteolysis is the most common mode of failure of arthroplasty. Osteolysis is the resultant of complex contribution of the generated wear debris and the mechanical instability of the prosthetic components. Roughly speaking, all orthopedic biomaterials may induce a universal biologic host response to generated wear débris with little specific characteristics for each material; but some debris has been shown to be more cytotoxic than others. Prosthetic wear debris induces an extensive biological cascade of adverse cellular responses, where macrophages are the main cellular type involved in this hostile inflammatory process. Macrophages cause osteolysis indirectly by releasing numerous chemotactic inflammatory mediators, and directly by resorbing bone with their membrane microstructures. The bio-reactivity of wear particles depends on two major elements: particle characteristics (size, concentration and composition) and host characteristics. While any particle type may enhance hostile cellular reaction, cytological examination demonstrated that more than 70% of the debris burden is constituted of polyethylene particles. Comprehensive understanding of the intricate process of osteolysis is of utmost importance for future development of therapeutic modalities that may delay or prevent the disease progression.

How has the introduction of new bearing surfaces altered the biological reactions to byproducts of wear and modularity?

BACKGROUND

Biological responses to wear debris were largely elucidated in studies focused on conventional ultrahigh-molecular-weight polyethylene (UHMWPE) and some investigations of polymethymethacrylate cement and orthopaedic metals. However, newer bearing couples, in particular metal-on-metal but also ceramic-on-ceramic bearings, may induce different biological reactions.

QUESTIONS/PURPOSES

Does wear debris from the newer bearing surfaces result in different biological responses compared with the known responses observed with conventional metal-on-UHMWPE bearings?

METHODS

A Medline search of articles published after 1996 supplemented by a hand search of reference lists of included studies and relevant conference proceedings was conducted to identify the biological responses to orthopaedic wear debris with a focus on biological responses to wear generated from metal-on-highly crosslinked polyethylene, metal-on-metal, ceramic-on-ceramic, and ceramic-on-polyethylene bearings. Articles were selected using criteria designed to identify reports of wear debris particles and biological responses contributing to prosthesis failure. Case reports and articles focused on either clinical outcomes or tribology were excluded. A total of 83 papers met the criteria and were reviewed in detail.

RESULTS

Biological response to conventional UHMWPE is regulated by the innate immune response. It is clear that the physical properties of debris (size, shape, surface topography) influence biological responses in addition to the chemical composition of the biomaterials. Highly crosslinked UHMWPE particles have the potential to alter, rather than eliminate, the biological response to conventional UHMWPE. Metal wear debris can generate elevated plasma levels of cobalt and chromium ions. These entities can provoke responses that extend to the elicitation of an acquired immune response. Wear generated from ceramic devices is significantly reduced in volume and may provide the impression of an "inert" response, but clinically relevant biological reactions do occur, including granulomatous responses in periprosthetic tissues.

CONCLUSIONS

The material composition of the device, the physical form of the debris, and disease pathophysiology contribute to complex interactions that determine the outcome to all wear debris. Metal debris does appear to increase the complexity of the biological response with the addition of immunological responses (and possibly direct cellular cytotoxicity) to the inflammatory reaction provoked by wear debris in some patients. However, the introduction of highly crosslinked polyethylene and ceramic bearing surfaces shows promising signs of reducing key biological mechanisms in osteolysis.

How have new bearing surfaces altered the local biological reactions to byproducts of wear and modularity?

BACKGROUND

The biologic reactions to byproducts of wear or corrosion can involve innate and adaptive processes and are dependent on many factors, including the composition, size, surface properties, shape, and concentration of debris.

QUESTIONS/PURPOSES

We used a systematic literature review to compare the reported patterns of inflammation in tissues around total hip implants with the goal of identifying whether there are unique or characteristic patterns associated with the newer bearing options or modular components.

METHODS

A search of the Ovid Medline database between 1996 and early December 2013 identified articles that compared the histology around six implant groups: (1) metal-on-metal; (2) ceramic-on-ceramic; (3) metal-on-crosslinked polyethylene; (4) metal-on-conventional polyethylene with or (5) without modularity; and (6) tissue obtained at primary arthroplasty. Our initial search yielded 865 citations. After excluding articles that lacked a quantitative or semiquantitative description of histologic findings in periprosthetic tissue, we reviewed 34 articles.

RESULTS

No pattern of inflammation is specific for any given bearing combination. Histologic features suggestive of an adaptive immune response appear to be more frequent and of greater magnitude in failed metal-on-metal implants, but tissues around many failed metal-on-metal implants show features of an "innate" foreign body reaction without lymphocytes. Occasional nonmetal-on-metal implants show features of an immune reaction, possibly associated with metal particles. Modular connections are one source of metal debris in nonmetal-on-metal implants. Features of an immune reaction appear rare in ceramic-on-ceramic implants that lack corrosion. Insufficient reports are available to characterize the biologic response to crosslinked polyethylene.

CONCLUSIONS

All total hip bearing combinations will wear in vivo, and modular interfaces are a likely source of metal that may be associated with a biological response regardless of the composition of the bearing surfaces. Surgeons must weigh the potential advantages of each articular combination and modular connection with the potential adverse tissue reactions in any given patient. Additional work is needed to clarify the implant and host-related factors associated with adverse tissue reactions and that seem to induce an immune reaction in some patients.

Retrieval analysis of alumina ceramic-on-ceramic bearing couples

BACKGROUND AND PURPOSE

Ceramic-on-ceramic (CoC) bearings have been in use in total hip replacement (THR) for more than 40 years, with excellent long-term survivorship. Although there have been several simulator studies describing the performance of these joints, there have only been a few retrieval analyses. The aim of this study was to investigate the wear patterns, the surface properties, and friction and lubrication regimes of explanted first-generation alumina bearings.

MATERIALS AND METHODS

We studied 9 explanted CoC bearings from Autophor THRs that were revised for aseptic loosening after a mean of 16 (range 7-19) years. The 3D surface roughness profiles of the femoral heads and acetabular cups (Srms, Sa, and Ssk) were measured to determine the microscopic wear. The bearings were imaged using an atomic-force microscope in contact mode, to produce a topographical map of the surfaces of the femoral heads. Friction tests were performed on the bearing couples to determine the lubrication regime under which they were operating during the walking cycle. The diametral clearances were also measured.

RESULTS

3 femoral heads showed stripe wear and the remaining 6 bearings showed minimal wear. The femoral heads with stripe wear had significantly higher surface roughness than the minimally worn bearings (0.645 vs. 0.289, p = 0.04). High diametral clearances, higher than expected friction, and mixed/boundary lubrication regimes prevailed in these retrieved bearings.

INTERPRETATION

Despite the less than ideal tribological factors, these first-generation CoC bearings still showed minimal wear in the long term compared to previous retrieval analyses.

Ceramic debris in hip prosthesis: correlation between synovial fluid and joint capsule

Detection of ceramic particles in synovial fluids allows early diagnosis of ceramic damage, but there is no evidence of a relationship between ceramic debris in the articular space and in the joint capsule. The aim of the present study is to verify if the particles isolated in the synovial fluid are comparable with those stored in the capsular tissue. Twenty-one patients were enrolled. Both synovial fluid and capsular samples were collected during revision surgery and ceramic particles were isolated and analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis. It resulted a significant correlation between the samples couples (18 out of 21). This study confirms that the synovial fluid analysis can give a clear definition of the presence of particles in the joint capsule.

Catastrophic failure of ceramic-on-ceramic total hip arthroplasty presenting as squeaking hip

A 68-year-old woman with osteoarthritis had a ceramic-on-ceramic left total hip arthroplasty, including ceramic femoral head and acetabular liner. At 5 years after surgery, the patient developed onset of a very loud squeaking noise, which could be heard 25 m from her, associated with limited hip movement. Findings at revision surgery included a broken ceramic femoral head component, complete wear of the ceramic acetabular component, and black wear debris. Squeaking hip after ceramic-on-ceramic total hip arthroplasty may be associated with catastrophic failure of the arthroplasty components.

Orthopaedic research in italy: state of the art

The most significant results in experimental and clinical orthopaedic research in Italy within the last three years have been primarily in major congenital diseases, bone tumors, regenerative medicine, joint replacements, spine, tendons and ligaments. The data presented in the following discussion is comparable with leading international results, highlighting Italian orthopaedic research excellemce as well as its shortcomings.

Acetabular orientation with different pelvic registration landmarks

This study determined the relationship of various pelvic landmarks to the pelvic plane in the lateral position. Five whole-body cadavers were used in this study. All navigation data were collected using the OrthoPilot navigation system (B. Braun Aesculap, Tuttlingen, Germany) to register all landmarks. The pelvic plane was registered with the body in the supine position for comparison. The ipsilateral posterosuperior iliac spine (PSIS) and contralateral PSIS were registered for comparison of the line made by the 2 anterosuperior iliac spines (ASIS) in the supine position. Registration points along the acetabular rim at the 12-, 3-, and 9-o'clock positions were recorded, and the transverse acetabular ligament (TAL) was registered using the ends and middle of the ligament for the 3 registration points. Inclination as determined by the TAL was 49.7 degrees +/-25.8 degrees , whereas the acetabular rim resulted in an inclination of 36.3 degrees +/-7.2 degrees . When the interspinal posterior line was calculated, the difference in inclination compared with the pelvic plane was 1.8 degrees +/-1.7 degrees . Anteversion using the acetabular rim resulted in a difference of 8.1 degrees +/-4.9 degrees and using the TAL resulted in a difference of 13.4 degrees +/-7.9 degrees . The difference in anteversion using the pelvic plane and the posterior interspinal line was 1.2 degrees +/-1.3 degrees . This study determined that the alternative landmarks of the acetabular rim and the TAL were not as accurate as using the posterior interspinal line as determined by registering the PSIS.