Debris from failed ceramic-on-ceramic and ceramic-on-polyethylene hip prostheses

Pelvic Pseudotumor Associated With a Ceramic Bearing Total Hip

Pseudotumors have been well documented to occur most frequently in metal-metal bearing total hip arthroplasties and less frequently in metal-polyethylene bearings. There are few cases in the literature of pseudotumors occurring in ceramic-ceramic articulations. We report a case of a large pelvic pseudotumor in a patient with a ceramic-ceramic bearing articulation in a 67-year-old man. In addition to the usual investigations, we did a detailed wear analysis of the ceramic implants and an examination of the soft tissues for particulate debris. The detailed wear analysis did show evidence of stripe wear; however, the volumetric wear was within the expected range. Synchrotron imaging identified strontium and zirconium debris arising from the ceramic surfaces. Although association does not mean causation, no other cause for the large pseudotumor could be identified and presumably represents an idiosyncratic reaction to ceramic debris.

Outcomes of Ceramic-On-Ceramic Bearing Total Hip Arthroplasty: A Minimum 10-Year Follow-Up Study

BACKGROUND

Although the fourth generation of ceramics has demonstrated excellent clinical results 5 to 6 years postoperatively, concerns over ceramic fracture and squeaking persist and longer-term follow-up (minimum 10 years) studies are warranted. Our study aimed to evaluate the minimum 10-year clinical outcomes and bearing-specific complications of ceramic-on-ceramic (CoC) total hip arthroplasties.

METHODS

We retrospectively evaluated all patients who underwent primary delta CoC total hip arthroplasty in our institution between January 2004 and February 2013. Demographics, surgical techniques, complications, patient-reported outcomes, and radiographic outcomes were collected and analyzed. For continuous variables, the comparison between groups was conducted using a one-way analysis of variance. Of all 235 patients included in the study, 70.5% were women (190 hips). The mean follow-up period was 12 years (range, 10 to 18). The femoral head sizes of 28- mm, 32 mm, and 36 mm were used in 50, 26, and 197 cases, respectively. Mean acetabular inclination and anteversion angles were 39.2 ± 7.1° and 14.9 ± 3.5°.

RESULTS

There were 5 hips revised at a mean 4.6 years (range, 0.1 to 7.1). One revision was squeaking-related. Squeaking was also reported by 8 other patients, but did not require revision. Other reasons for revision were early infection in 2 cases, stem loosening in 1 case, and stem fracture in 2 cases. The survival analysis for any causes for revision as an endpoint was 96.7% (95% confidence interval 0.313%-2.57%).

CONCLUSION

We report excellent mean 12-year follow-up results regarding the complications and survivorship of the fourth generation CoC bearings.

Aluminum Nanoparticles Affect Human Platelet Function In Vitro

Endoprostheses are prone to tribological wear and biological processes that lead to the release of particles, including aluminum nanoparticles (Al NPs). Those particles can diffuse into circulation. However, the toxic effects of NPs on platelets have not been comprehensively analyzed. The aim of our work was to investigate the impact of Al NPs on human platelet function using a novel quartz crystal microbalance with dissipation (QCM-D) methodology. Moreover, a suite of assays, including light transmission aggregometry, flow cytometry, optical microscopy and transmission electron microscopy, were utilized. All Al NPs caused a significant increase in dissipation (D) and frequency (F), indicating platelet aggregation even at the lowest tested concentration (0.5 µg/mL), except for the largest (80 nm) Al NPs. A size-dependent effect on platelet aggregation was observed for the 5-20 nm NPs and the 30-50 nm NPs, with the larger Al NPs causing smaller increases in D and F; however, this was not observed for the 20-30 nm NPs. In conclusion, our study showed that small (5-50 nm) Al NPs caused platelet aggregation, and larger (80 nm) caused a bridging-penetrating effect in entering platelets, resulting in the formation of heterologous platelet-Al NPs structures. Therefore, physicians should consider monitoring NP serum levels and platelet activation indices in patients with orthopedic implants.

An Atypical Adverse Local Tissue Reaction After Ceramic-on-Ceramic Primary Total Hip Arthroplasty

Adverse local tissue reaction is an uncommon but frequently described complication after total hip arthroplasty (THA). It is most often associated with metal-on-metal hips and less frequently with metal-on-polyethylene implants as part of a mechanically assisted crevice corrosion process. In this report, we describe a rare case of an atypical adverse local tissue reaction in a patient with a ceramic-on-ceramic THA. Abrasive backside liner wear from a prominent screw head, failure of the liner locking mechanism, and liner fragmentation secondary to component-component impingement created an atypical mass and fluid collection leading to THA failure. This case demonstrates the importance of appropriate cup-liner positioning, thorough workup of pain after THA, and the ability of ceramic debris to cause an associated, atypical adverse local tissue reaction.

Adverse local tissue reaction after ceramic-on-ceramic total hip arthroplasty

We report a rare case of symptomatic adverse local tissue reaction in a patient with a ceramic-on-ceramic total hip bearing surface and review the literature. Probably, ceramic wear debris is not entirely inert and may lead to adverse local tissue reactions.

IL-17A-Mediated Immune-Inflammatory Periarticular Mass and Osteolysis From Impingement in Ceramic-On-Ceramic Total Hip Arthroplasty

We present a rare case of symptomatic adverse local tissue reaction in a 54-year-old female patient who had undergone total hip arthroplasty with ceramic-on-ceramic bearing. Inflammatory periarticular mass and osteolysis developed in the absence of cobalt chrome alloy interfaces and a modular neck component. On the pathologic images, there was no clear evidence of gross metal staining of tissues, metal corrosion, and ceramic or metal wear particles. However, there were impingement scars on the titanium alloy femoral neck and acetabular cup associated with a high combined anteversion angle of 75° (stem: 40° and cup: 35°), suggesting titanium debris release in vivo. Immunohistochemical staining proved a predominant infiltration of CD4+ T cells and the corresponding IL-17A response to metal. We conclude that neck-rim impingement may lead to the development of adverse local tissue reaction (periarticular mass and osteolysis) due to a metal hypersensitivity with the production of proinflammatory cytokines (IL-17A) by CD4+ T cells even in ceramic-on-ceramic total hip arthroplasty.

Impingement of metal-polyethylene hip prostheses : Potential cause of high systemic titanium levels?

High blood metal levels have been described in the past, primarily in metal-on-metal bearings. Other possible causes are often underestimated. This report presents the case of a 70-year-old female patient who suffered from pronounced neurological symptoms (especially fatigue and concentration problems) 13 years after implantation of a hip endoprosthesis with metal-polyethylene (ME-PE) bearing. An osteolysis in the pelvis and loosening of the acetabular component were detected. In addition, large quantities of metallic black discolored granulomas were detected in the periarticular environment during surgery. A ventral impingement with destruction of the titanium cup and the PE insert was identified as the suspected cause of this condition. The postoperative course of the blood metal levels was unexpected as titanium levels increased massively in the blood. Anamnesis, course of the disease and the surgical procedure as well as especially the course of the metal values in the blood of the patient are presented. Possible causes for the excessive occurrence of metal abrasion, the systemic distribution and potential toxic effects of titanium are explained and discussed in detail. In addition, the currently available literature on the subject is critically examined.

Evaluation of Aerosol Electrospray Analysis of Metal-on-Metal Wear Particles from Simulated Total Joint Replacement

Wear is a common cause for aseptic loosening in artificial joints. The purpose of this study was to develop an automated diagnostical method for identification of the number and size distribution of wear debris. For this purpose, metal debris samples were extracted from a hip simulator and then analyzed by the electrospray method combined with a differential mobility analyzer, allowing particle detection ranging from several nanometers up to 1 µm. Wear particles were identified with a characteristic peak at 15 nm. The electrospray setup was successfully used and validated for the first time to characterize wear debris from simulated total joint replacement. The advantages of this diagnostic method are its time- and financial efficiency and its suitability for testing of different materials.

Recovery of low volumes of wear debris from rat stifle joint tissues using a novel particle isolation method

Less than optimal particle isolation techniques have impeded analysis of orthopaedic wear debris in vivo. The purpose of this research was to develop and test an improved method for particle isolation from tissue. A volume of 0.018 mm³ of clinically relevant CoCrMo, Ti-6Al-4V or Si₃N₄ particles was injected into rat stifle joints for seven days of in vivo exposure. Following sacrifice, particles were located within tissues using histology. The particles were recovered by enzymatic digestion of periarticular tissue with papain and proteinase K, followed by ultracentrifugation using a sodium polytungstate density gradient. Particles were recovered from all samples, observed using SEM and the particle composition was verified using EDX, which demonstrated that all isolated particles were free from contamination. Particle size, aspect ratio and circularity were measured using image analysis software. There were no significant changes to the measured parameters of CoCrMo or Si₃N₄ particles before and after the recovery process (KS tests, p > 0.05). Titanium particles were too few before and after isolation to analyse statistically, though size and morphologies were similar. Overall the method demonstrated a significant improvement to current particle isolation methods from tissue in terms of sensitivity and efficacy at removal of protein, and has the potential to be used for the isolation of ultra-low wearing total joint replacement materials from periprosthetic tissues.

STATEMENT OF SIGNIFICANCE

This research presents a novel method for the isolation of wear particles from tissue. Methodology outlined in this work would be a valuable resource for future researchers wishing to isolate particles from tissues, either as part of preclinical testing, or from explants from patients for diagnostic purposes. It is increasingly recognised that analysis of wear particles is critical to evaluating the safety of an orthopaedic device.

Inflammatory pseudotumor after ceramic-on-ceramic total hip arthroplasty

We present a unique case of a symptomatic adverse local tissue reaction in a patient with a ceramic-on-ceramic total hip bearing surface. To our knowledge, this pathological finding has not yet been described in a ceramic-on-ceramic articulation without a cobalt-chromium alloy trunnion or modular neck component as a source of metal wear. We conclude that despite its mechanical mostly benign wear characteristics, ceramic wear debris is not entirely inert and may lead to the development of adverse local tissue reaction.

Ceramic on Ceramic or Ceramic-on-polyethylene for Total Hip Arthroplasty: A Systemic Review and Meta-analysis of Prospective Randomized Studies

BACKGROUND

Wear debris of polyethylene has become a restraining factor of the durability for total hip arthroplasty (THA). Ceramic on ceramic (COC) has better wear resistance while the squeaking sound and prosthesis fracture are of concern. It is still a controversy that bearing couples are better for THA.

METHODS

We performed a systematic review of all English articles identified from PubMed (1966-), Embase (1980-) and the Cochrane Library. Clinical outcomes, complications, revision rates, and radiographic outcomes of COC-THA and ceramic on polyethylene (COP)-THA were compared and evaluated.

RESULTS

Eight prospective randomized trials enrolling a total of 1508 patients and 1702 THA surgeries were identified. Our results demonstrated the prosthesis fracture and the squeaking sound is significantly higher in COC group and higher wear rate of the COP. Hip function, loosening rate, dislocation rate, revision rate, and the osteolysis rate were comparable between two groups. According to Grading of Recommendations Assessment, Development and Evaluation system assessment, the strength of evidence was high for prosthesis fracture, dislocation, osteolysis, and moderate for radiolucent line or loosening, hip noise, and revision.

CONCLUSIONS

Up to now, there is insufficient evidence to identify any clinical advantage of COC compared with COP. Longer follow-up of larger randomized trial is needed to clarify the outcomes.

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.

Wear Debris Characterization and Corresponding Biological Response: Artificial Hip and Knee Joints

Wear debris, of deferent sizes, shapes and quantities, generated in artificial hip and knees is largely confined to the bone and joint interface. This debris interacts with periprosthetic tissue and may cause aseptic loosening. The purpose of this review is to summarize and collate findings of the recent demonstrations on debris characterization and their biological response that influences the occurrence in implant migration. A systematic review of peer-reviewed literature is performed, based on inclusion and exclusion criteria addressing mainly debris isolation, characterization, and biologic responses. Results show that debris characterization largely depends on their appropriate and accurate isolation protocol. The particles are found to be non-uniform in size and non-homogeneously distributed into the periprosthetic tissues. In addition, the sizes, shapes, and volumes of the particles are influenced by the types of joints, bearing geometry, material combination, and lubricant. Phagocytosis of wear debris is size dependent; high doses of submicron-sized particles induce significant level of secretion of bone resorbing factors. However, articles on wear debris from engineered surfaces (patterned and coated) are lacking. The findings suggest considering debris morphology as an important parameter to evaluate joint simulator and newly developed implant materials.

Comparison of surgical outcomes and implant wear between ceramic-ceramic and ceramic-polyethylene articulations in total hip arthroplasty

The results of a prospective multicenter trial comparing 357 hips randomized to total hip arthroplasty with either ceramic-ceramic or ceramic-polyethylene couplings are presented. No statistically significant difference in clinical outcomes scores between the ceramic-ceramic and ceramic-polyethylene groups was observed at any time interval. The mean linear rate was statistically lower (P < .001) in the ceramic-ceramic group (30.5 μm/year) when compared with the ceramic-polyethylene group (218.2 μm/year). The rates of ceramic implant fracture (2.6%) and audible component-related noise (3.1%) were statistically higher in the ceramic-ceramic group when compared with the ceramic-polyethylene group (P < .05). Lastly, there was no statistically significant difference in the dislocation or revision rate between the groups at the time of last clinical follow-up.

Submicron sized ultra-high molecular weight polyethylene wear particle analysis from revised SB Charité III total disc replacements

Submicron sized particles are frequently observed in retrieved total hip and knee periprosthetic tissues and appear to be critical in the activation of the phagocytic inflammatory response. In this paper the concentration, size and shape of ultra-high molecular weight polyethylene (UHMWPE) wear particles between 0.05 and 2.00μm were determined after isolation from periprosthetic tissues from retrieved lumbar SB Charité III total disc replacements (TDR) using scanning electron microscopy (SEM). For comparison, UHMWPE wear particles were isolated from γ-radiation-air sterilized total hip arthroplasty (THA) revision tissues. The mean concentration of UHMWPE particles in TDR tissues was 1.6×10(9)g(-1)tissue (range 1.3-2.0), which was significantly lower than the concentration of 2.3×10(9)g(-1) THA revision tissue (range 1.8-3.2) (P=0.03). The mean particle size (equivalent circular diameter: TDR, 0.46μm; THA 0.53μm, P=0.60) and mean shape were comparable between TDR and THA (aspect ratio: TDR, 1.89; THA, 1.99, P=0.35; roundness: TDR, 0.58; THA, 0.56, P=0.35). However, the TDR particles tended to be smaller and more round. Although no correlations were found between visible damage to the UHMWPE core and the concentration or shape of the UHMWPE particles, a positive correlation was found between increasing particle size and increasing rim penetration of the TDR core (P=0.04). The presence of UHMWPE particles of similar size and shape in TDR tissue, albeit lower in concentration, might explain why, unlike THA, pain rather than osteolysis is the major reason for revision surgery.

Metal neck and liner impingement in ceramic bearing total hip arthroplasty

Although impingement between the neck of the metallic stem and the ceramic liner has been suspected to be the cause of ceramic liner failure in ceramic-on-ceramic total hip arthroplasty (THA), no report has directly demonstrated microscopic damage on ceramic liner. We performed 18 reoperations on 18 patients who had undergone third generation ceramic-on-ceramic THA. Considering impingement, 16 patients, who were reoperated more than 1 year after previous ceramic bearing THA, were evaluated. Retrieved alumina liners, showing evidence of impingement, were examined by means of visual inspection and scanning electron microscopy (SEM). Four of the 16 hips showed neck notching and black stained liners, evidence of metallic neck to ceramic impingement. Impinged alumina bearings had been implanted for an average of 62.5 months (range: 35-99 months) before reoperation. SEM of the black stained area demonstrated disruptive wear and loss of surface integrity. Furthermore, one liner had multiple microcracks, and its cross-sectional SEM analysis revealed one microcrack propagating into the deep portion of the ceramic liner. Our observations suggest that metal neck-to-ceramic impingement in ceramic-on-ceramic THA can cause microcrack formation in ceramic liner.

Thirty years of experience with alumina-on-alumina bearings in total hip arthroplasty

Alumina-on-alumina bearings in total hip arthroplasty have been developed in an attempt to minimise debris and the occurrence of osteolytic lesions. The outstanding tribological properties of this bearing system are explained by low surface roughness, high hardness for major scratch resistance, and high wettability. Since the 1970s, technological improvements in the manufacturing process of alumina components together with a better understanding of Morse taper technology have provided a surgical grade material with high density, high purity and small grains. Published studies on the outcome of total hip arthroplasty performed with this new generation of implants showed high survivorship especially in young and active patients, with survival rates free of revision of 90.8% to 97.4% at ten years. However, concern remains over ceramic liner fracture and squeaking, which has been noted recently with increasing prevalence. This review will discuss the current knowledge on the use of alumina-on-alumina bearings.

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

BACKGROUND AND PURPOSE

Ceramic-on-ceramic articulation is an attractive alternative to metal-on-polyethylene (PE) bearings, but little is known about the in vivo effects induced by dissemination of alumina wear debris in the periprosthetic tissues. We hypothesized that wear debris is not the main factor responsible for loosening and failure of the implant but that mechanical problems caused by incorrect surgical technique, prosthetic design, or trauma, may cause instability of the implants and result in production of wear debris.

PATIENTS AND METHODS

Clinical, radiographic, laboratory, and microbiological data from 30 consecutive patients with failed alumina-on-alumina arthroplasties, 19 with screwed socket and 11 with press-fit socket, were systematically collected and evaluated. Retrieved peri-implant tissues and prosthesis wear were also analyzed.

RESULTS AND INTERPRETATION

Loosening was due to malpositioning, primary mechanical instability, trauma, or infection. Bone stock was generally preserved, even if screwed implants showed higher levels of osteolysis. Variable implant wear and tissue macrophage reaction were present but activation of giant cells/osteoclasts was not induced, and no correlation between histocytic reaction and the level of osteolysis was found. These findings indicate that, in contrast to the situation with metal-on-PE bearings, wear debris and occasional osteolysis were the effect rather than the cause of failure of ceramic-on-ceramic implants, and that press-fit socket fixation was the socket fixation design of preference.

Fabrication and testing of silicon nitride bearings in total hip arthroplasty: winner of the 2007 "HAP" PAUL Award

Total hip arthroplasty (THA) bearings were fabricated from silicon nitride (Si(3)N(4)) powder. Mechanical testing showed that Si(3)N(4) had improved fracture toughness and fracture strength over modern alumina (Al(2)O(3)) ceramic. When tested with Si(3)N(4) cups in a hip simulator, both cobalt-chromium (CoCr) and Si(3)N(4) femoral heads produced low wear rates that were comparable to Al(2)O(3)-Al(2)O(3) bearings in THA. This study offers experimental support for a novel metal-ceramic THA bearing couple that combines the reliability of CoCr femoral heads with the wear advantages of ceramic surfaces.

The combined role of wear particles, macrophages and lymphocytes in the loosening of total joint prostheses

This review considers the causes of loosening of prosthetic joint replacement paying attention to the biological mechanisms rather than other effects that are physical, such as component fracture and other failure related to mechanical problems. Infection accounts for approximately 1.5 per cent of joint loosening and when it occurs it is a cause of serious concern to the surgeon. The loosening of prosthetic joints in the absence of infection is by far the most common reason for revision surgery and is known as aseptic loosening. While this may be multifactorial in terms of causation, and non-biological factors may contribute significantly in a particular individual, a significant part is undoubtedly played by the generation of wear debris, mainly from the bearing surfaces of the joint, and the cellular reaction to this in the implant bed. Phagocytic cells (macrophages and multinucleated giant cells) are the ones that remove foreign material from the tissues, and the ways in which these cells function in the interface between implant and bone are described. Mediators produced locally include numerous cytokines, enzymes and integrins. There is evidence for interactions between macrophages and locally recruited lymphocytes, which may or may not give rise to an immunologically mediated process.Sensitization of individuals having metal implants in place has been shown by positive skin tests or blood lymphocyte transformation tests and in these cases has been accompanied by loosening and failure of the replacement joint. The question remains as to whether this process is also present in a proportion of individuals with aseptic loosening in the absence of clearly defined clinical evidence of sensitization.Numerous studies performed by the author's group and, latterly, by others suggest that the cellular reactions detected in the tissues in cases of aseptic loosening are indeed those of contact sensitization. There is good evidence to show that a type IV cell-mediated immune reaction is taking place, with TH1 cell involvement and active antigen presentation. The extent to which sensitization is present in individual cases of aseptic loosening remains a subject for further work and this needs all the sophisticated molecular methods now available to modern biology to be applied in appropriate prospective clinical studies coupled with experimental models in vitro and in vivo. Immunological processes may play a more important part in joint loosening than previously considered.

Osteolysis in third-generation alumina ceramic-on-ceramic hip bearings with severe impingement and titanium metallosis

The most common cause of long-term failure of total hip arthroplasty is osteolysis and aseptic loosening secondary to wear debris. Combinations of hard materials such as ceramic-on-ceramic generate smaller volumes of particulate wear debris than traditional combinations such as metal-on-polyethylene. We describe 2 cases where osteolysis arose in hips with third-generation alumina ceramic-on-ceramic couplings. Periarticular tissue in both cases contained titanium wear debris due to impingement of the neck of the titanium femoral component against the rim of the titanium shell and ceramic debris from edge loading wear (stripe wear) of the ceramic. It is not clear whether the titanium debris, the ceramic debris, or both caused the osteolysis. These cases illustrate that the risk of osteolysis persists, even with third-generation alumina ceramics.

Identification of nanometre-sized ultra-high molecular weight polyethylene wear particles in samples retrieved in vivo

Nanometre-sized particles of ultra-high molecular weight polyethylene have been identified in the lubricants retrieved from hip simulators. Tissue samples were taken from seven failed Charnley total hip replacements, digested using strong alkali and analysed using high-resolution field emission gun-scanning electron microscopy to determine whether nanometre-sized particles of polyethylene debris were generated in vivo. A randomised method of analysis was used to quantify and characterise all the polyethylene particles isolated. We isolated nanometre-sized particles from the retrieved tissue samples. The smallest identified was 30 nm and the majority were in the 0.1 microm to 0.99 microm size range. Particles in the 1.0 microm to 9.99 microm size range represented the highest proportion of the wear volume of the tissue samples, with 35% to 98% of the total wear volume comprised of particles of this size. The number of nanometre-sized particles isolated from the tissues accounted for only a small proportion of the total wear volume. Further work is required to assess the biological response to nanometre-sized polyethylene particles.

A case report of fracture of ceramic head in total hip arthroplasty: histological and biochemical features of perimplant tissues

The authors analyzed the case of a patient with a non-cemented hip prosthesis with a ceramic-ceramic coupling. As a consequence of trauma the head fractured. Although the patient could feel the joint grinding, there was no pain and he continued daily living activities for nearly six months, which led to marked wearing of the ceramic head. SEM analysis with microprobe showed 'planed' surfaces on the ceramic head, suggesting repeated movements between the fractured components. Inside the cone of the head, signs of TiAlV, which is an alloy of the prosthetic stem, could be seen. Periprosthetic tissues were packed with ceramic wear particles of sizes ranging between 0.2 and 10 microns, according to the harvest site. Metal and mixed particles were also found. IL1, IL6, IL8 and IL10 assays in the synovial liquid confirmed the inflammatory state and a modest induction of bone resorption, which was less than that observed in patients with loosened metal-polyethylene couplings. The humoral picture was compatible with the radiological aspect, which did not show marked signs of bone resorption. In revision surgery both ceramic components were replaced by a metal head and polyethylene liner. The clinical outcome after 12 months was very good.

No difference in early cellular response of the pseudo-synovial membrane after total hip arthroplasty: comparison of 3 combinations of bearing materials

BACKGROUND

Wear-resistant bearing materials may hypothetically reduce chronic inflammation in the pseudosynovial membrane as compared to less wear-resistant bearing materials such as polyethylene. We assessed the foreign body response in the pseudosynovial membrane in vivo after total hip replacement.

METHODS

37 patients from a larger prospective randomized trial of 225 patients had biopsies taken arthroscopically from the artificial hip joint (i.e. the pseudosynovial membrane) 1 year after insertion of the implant. All patients had an identical hip prosthesis (Bimetric-RingLoc) except for the bearing materials, which consisted of polyethylene on zirconia, CoCr on CoCr, or alumina on alumina. Histological quantification was performed on 2-mum-thick semi-thin plastic sections or paraffin sections by point counting technique to compare the volume fraction of macrophages, granulomas and endothelial cells in biopsies of the pseudosynovial membrane.

RESULTS

The median macrophage volume fractions for polyethylene-on-zirconia bearing material (n = 15), CoCr-on-CoCr (n = 9), and alumina-on-alumina (n = 11) were 0.02, 0.04, and 0.004, respectively. The median granuloma volume fractions for polyethylene-on-zirconia (n = 13), CoCr-on-CoCr (n = 9), and alumina-on-alumina (n = 13) were 0.02, 0.04, and 0.02, respectively. The median endothelial cell volume fractions for polyethylene-on-zirconia (n = 15), CoCr-on-CoCr (n = 9), and alumina-on-alumina (n = 11) were 0.03, 0.02, and 0.05, respectively. Statistical analysis showed no significant differences between the three groups with the different bearings with respect to volume fraction of macrophages, granulomas and endothelial cells.

INTERPRETATION

Our study demonstrated that a granulomatous inflammation is a common finding in non-loose implants as early as 1 year after the operation not demonstrating a difference in macrophages and granuloma formation with the various bearing materials. Thus a high volume fraction of macrophages was found in the osteoarthritis control group compared to the operated group.

[Arthrosynovial cyst of the hip after total hip arthroplasty with a ceramic-on-ceramic interface]

An inguinal arthrosynovial cyst of the hip joint developed after total hip arthroplasty leading to compression of the femoral vein. This complication occurred after implantation of a non-cemented prosthesis with a ceramic-on-ceramic interface inserted in a polyethylene sandwich. Multiple foreign bodies composed of both ceramic and polyethylene particles were visualized microscopically. Later, rupture of the joint interface required implant replacement. This cyst was a precursor sign of a deteriorating prosthesis surface.

Concerns about ceramics in THA

Currently available ceramic materials are superior to those used originally in total hip arthroplasty, which should translate into a much lower complication rate than what has been reported previously. In spite of this, a number of concerns remain. The ceramic-on-ceramic articulation is not immune to wear and surface damage. Conditions associated with ceramic wear include vertical cup position, femoral neck impingement, and femoral head separation. A unique pattern of stripe wear has been described as something that results from microseparation during gait. Catastrophic failure, although rare, continues to be a concern, and not all fractures can be predicted by proof testing. Revisions needed because of ceramic fractures can be extensive, and the results of the revision procedures can be compromised by the presence of highly abrasive particulate debris that is retained. Other concerns include the generation of debris from modular interfaces, neck damage and debris generation from impingement of some designs, inability to use a ceramic head a second time on a metal trunnion, and the dramatic loss of head and liner options intraoperatively. Although ceramics show great promise as a lower wear articulation, manufacturing and design modifications and improvements will continue in an attempt to address the substantial concerns that persist.