Ceramic Femoral Heads Research Articles

Accelerating aging of zirconia femoral head implants: Change of surface structure and mechanical properties

Recently, alternations of zirconia ceramic femoral heads of total hip prostheses during in vivo conditions have caused concern in the medical disciplines regarding phase transformation of zirconia prosthetic components. In this paper, we have investigated the mechanical and structural properties of different laboratory aged zirconia femoral heads and correlated changes in mechanical properties with the phase compositions of the sample. From laser microscope observation, cross-sectional Scanning electron microscopy imaging, and X-ray diffraction analysis on the surface of the zirconia femoral heads, we found monoclinic to tetragonal phase transformation in zirconia prostheses over time during the aging process in the laboratory. Mechanical properties, mainly hardness (H) and Young's modulus (E) values, were measured by nanoindentation technique on the surface of these implants. The results showed that both H and E values decreased with increased monoclinic phase in zirconia, thus confirming a phase transformation over time during aging.

Fracture of a Ceramic Femoral Head After Ceramic-On-Ceramic Total Hip Arthroplasty

A case of fracture of the ceramic head of a total hip arthroplasty is presented, which was a total cementless arthroplasty with ceramic-on-ceramic articulation. No history of trauma was observed. The arthroplasty was revised, and a new cementless arthroplasty with a polyethylene insert and a metal head was inserted. The result has been satisfactory.

Die Bedeutung der Setzkraft für die Sicherheit einer Konuskopplung von Hüftstiel und keramischem Prothesenkopf / Relevance of the insertion force for the taper lock reliability of a hip stem and a ceramic femoral head

In endoprosthetics alumina ceramic femoral heads have been established for many years and their outstanding wear characteristics are scientifically proven. The taper connection between the hard but brittle ceramic head and the metallic stem must be performed by the operating surgeon intraoperatively. Thereby it is left to the surgeon to interpret imprecise and strongly deviating instructions given from manufacturer to manufacturer. This study clarifies the enormously large variations of interpretation in the clinical everyday life based on interviews and force measurements during handling when assembling. In comparable situations the axial cone setting forces, applied by a total of 39 operating surgeons from German hospitals, varied between 273 N and 7848 N. An additional coupling strength examination in the laboratory shows that torque loadings necessary for loosening several cone connection designs are in the range of those occurring under usual in vivo situations. This leads to the conclusion that for low-force-connected cone tapers joint friction of the artificial hip joint can cause a rotation and thus a loosening of the ceramic head of the implant neck during everyday activities. The authors proclaim the urgent necessity for clear handling references and the supply of a reproducibly safe taper lock method.

Ceramic Failure After Total Hip Arthroplasty with an Alumina-on-Alumina Bearing

The mechanical properties of alumina ceramic, now in its third generation, have been markedly improved through the evolution of design features and manufacturing processes and the introduction of proof-testing. Nonetheless, because of the lack of ductility of alumina ceramic, there is concern regarding the risk of fracture during insertion or in vivo use. The purpose of the present study was to present a multicenter review of primary total hip arthroplasties performed with use of a polyethylene-ceramic composite liner combined with a ceramic femoral head, with particular attention to failure of the ceramic bearing. We evaluated 357 primary total hip arthroplasties that had been performed in 319 patients with use of a contemporary alumina-on-alumina bearing design incorporating a polyethylene-ceramic composite liner within a titanium-alloy shell coupled with a 28-mm-diameter ceramic femoral head. The procedures were performed at four participating centers from 1998 to 2001. Ceramic failure without trauma occurred in six hips (1.7%). All of these hips were revised, and the retrieved alumina implants were examined by means of visual inspection and scanning electron microscopy equipped with energy-dispersive x-ray spectrometry. Two femoral heads fractured during the first postoperative year, and four alumina liners fractured after an average of 36.8 months in vivo. All four of the explanted alumina liners revealed evidence of rim contact with the metal neck of the femoral component. Composition analysis confirmed that surface-stain materials were titanium particles transferred from the femoral component. Despite the theoretical improvement in the fracture toughness of a polyethylene-alumina composite liner, a relatively high rate of catastrophic ceramic bearing surface failure was still observed at the time of short-term follow-up. This finding prompted us to discontinue the use of this type of alumina bearing design.

Transfer of metallic debris after dislocation of ceramic femoral heads in hip prostheses

Main reasons for the early revision of total hip arthroplasties are aseptic loosening as a result of wear debris caused by polyethylene particles, and postoperative dislocations. In revision arthroplasty of the hip metallic deposits were frequently found on femoral heads after dislocation or repositioning in total hip arthroplasties with metal back acetabular components. In this study we examined ceramic femoral heads from alumina-on-alumina and alumina-on-polymer pairings, respectively. All the heads resulted from revision of total hip replacement with a titanium containing acetabular component and showed metallic deposit on their surface. The metallic deposit was characterized by environmental scanning electron microscopy, energy dispersive X-ray spectroscopy and laser scanning microscopy. The metallic deposits covered areas between 5 mm(2) and 8 cm(2) and reached a maximum height of 30 mum. They were shown to consist of titanium, and thus resulted from contact between the femoral head and the posterior part of the metal back. In case of twofold dislocated alumina-on-alumina pairings the titanium deposits showed different roughness profiles, whereas no differences were detectable for alumina-on-polymer pairings. From the obtained results it can be concluded, that titanium deposited onto a femoral head during dislocation will be abraded within the harder alumina-on-alumina bearing couple during normal gait and will subsequently be released into the body by synovial fluid. In case of a ceramic-on-polymer bearing the deposited metal seems to be more harmful. The increased surface roughness of the femoral head within the tribological pairing probably initiates damage of the polymeric acetabular inlay and increases the wear of the bearing surface through a third-body wear mechanism resulting in the release of high amounts of PE.

Severe damage of the femoral head after dislocation and difficult reduction maneuvers after total hip arthroplasty

Aseptic loosening associated with osteolysis and release of wear particles is the main reason for revision of total hip arthroplasty (THA). Damage of femoral heads is well known to increase the wear rate at the articulating surface. Instability and dislocation are serious complications and are the second most frequent reason for revision surgery after THA. In the present work the possible damaging of the femoral head as a result of difficult reduction maneuvers of dislocated THA should be investigated. In three cases of total hip dislocation an open reduction was performed after dislocation of primary THA. Thereby one metal and two ceramic femoral heads were retrieved. Each head was analyzed macroscopically and by scanning electron microscopy (SEM) subsequently. In the first case the SEM analysis revealed severe titanium deposits on the retrieved ceramic head in the case of repeated unsuccessful closed reduction maneuvers. In the second case the retrieved ceramic head showed multiple scratches and a spalling of the surface structure. In the third case the retrieved metal head presented a roughened surface and severe scratches at the articulating area. Difficult reduction maneuvers following total hip dislocation can lead to severe damaging of the femoral head associated with an increase of the surface roughness. While repeated reduction maneuvers can lead to metallic deposits and spalling of the surface of ceramic heads, severe scratches can occur at metal heads. The damaging of the femoral head at the articulating surface can lead to increased wear and subsequent aseptic implant loosening. Therefore, open joint reduction has to be considered in cases of difficult or unsuccessful closed reduction maneuvers to prevent severe femoral head damage which may cause an increased release of wear particles.

Total Hip Arthroplasty with Ceramic-on-Ceramic Articulation: Minimum 5-year Follow-up Results

Purpose : To evaluate the medium-term clinical and radiographic results of uncemented total hip arthroplasty with ceramic-on-ceramic articulation. Materials and Methods : From February 1999 to August 2000, fifty-two primary total hip arthroplasties were performed on forty-two patients using a ceramic-on-ceramic bearing implant. The mean follow-up period was 5.4 years (range, 5-6.6 years) and the mean age at surgery was 43.2 years (range, 19-66 years). The clinical results were evaluated using the Harris hip score. The radiographic evaluations were carried out in terms of the stability of the components, the prevalence of osteolysis and wear. Results : At the most recent follow-up, the mean preoperative Harris hip score improved from 63 points (range, 26-93 points) to 97 points (range, 82-100 points). The Harris hip score showed excellent results in 49 hips (94%) and good results in 3 hips (6%). Fixation by bone ingrowth was noted in all cases and there was no case with osteolysis or a deep infection. Ceramic wear was not detectable on the plain radiograph. Complications included one case of dislocation, one case of a fracture of the ceramic femoral head and one case of an intraoperative periprosthetic proximal femoral crack. Conclusion : Ceramic-on-ceramic articulation showed excellent clinical and radiographic results in terms of wear, osteolysis and loosening. A further follow-up study should be performed to evaluate the long-term clinical and radiographic results with special focus on the fracture of the ceramic material.

A simple fully integrated contact-coupled wear prediction for ultra-high molecular weight polyethylene hip implants

A fully coupled contact and wear model was developed in the present study for hip implants employing an ultra-high molecular weight polyethylene (UHMWPE) cup in combination with a metallic or ceramic femoral head. A simple elasticity equation based on the concept of constrained column model was employed to solve the contact mechanics between the acetabular cup and the femoral head under the three-dimensional physiological loading condition. The wear model was based on the classical Archard-Lancaster equation in common with all other studies reported in the literature. The fully coupled contact and wear model was applied to both conventional and cross-linked UHMWPE cups under a wide range of design parameters such as the clearance and the femoral head radius. The predicted linear and volumetric wear as well as their rates for conventional UHMWPE cups were found to be in good agreement with those obtained from a similar analysis by Maxian but using the finite element method for the contact mechanics analysis. The predicted maximum contact pressure was found to decrease rapidly within the first 10(6) cycles, and below the limit to cause plastic deformation within the UHMWPE cup with a nominal radial clearance of 0.2 mm. The effect of the clearance between the head and the cup on the predicted wear was found to be negligible. For the cross-linked UHMWPE cup with relatively large diameters up to 48 mm and a fixed outside diameter of 50 mm, the predicted wear, which was found to increase with increasing femoral head radius, remained small owing to the small wear factor associated with these materials. Furthermore, if the head diameter increases beyond 42 mm, a rapid increase in the contact pressure was predicted, owing to the decrease in the wall thickness of the cross-linked UHMWPE cup.

319 人工股関節用セラミックス骨頭の衝撃破壊メカニズム(OS3-4,オーガナイズドセッション3:臨床系のバイオメカニクス,学術講演)

319 人工股関節用セラミックス骨頭の衝撃破壊メカニズム(OS3-4,オーガナイズドセッション3:臨床系のバイオメカニクス,学術講演)

Ceramic femoral head fracture with massive metallosis and severe wear of the cone: a case report and review of the literature

A case of a fractured ceramic femoral head without subsequent trauma, 14 months after a primary total hip arthroplasty, in a 40-year-old woman with hip dysplasia is reported. Intraoperative findings were multifragment femoral head and a damaged polyethylene insert along with diffuse metallosis and excessive wear of the cone of the stem. Both the stem and the acetabular component were stable. After the removal of ceramic fragments, metallotic tissue excision and careful lavage of the joint, the inlay was replaced by a similar one and a cobalt–chromium femoral head was placed to the existing notched taper of the firmly incorporated stem. At 22-month follow-up examination, the patient had no pain, used no walking aids and had normal activity.

Mislabeling Leads to Recall Of Ceramic Femoral Heads

Mislabeling Leads to Recall Of Ceramic Femoral Heads

Total hip replacement with a zirconium oxide ceramic femoral head

We investigated the wear characteristics and clinical performance of four different total hip joint articulations in 114 patients. Wear and migration was measured by roentgenstereophotogrammetric analysis at five years or at the last follow-up. The mean annual wear was 0.11 mm for a stainless steel/Enduron articulation, 0.34 mm for stainless steel/Hylamer cup, 0.17 mm for zirconium oxide ceramic/Enduron and 0.40 mm for zirconium oxide ceramic/Hylamer. The difference between the groups was significant (p < 0.008) except for stainless steel/Hylamer vs zirconium oxide ceramic/Hylamer (p = 0.26). At present, 12 patients have undergone a revision procedure, four at five years and eight thereafter. No patient who received a stainless steel/Enduron articulation at their primary replacement required revision. Conflicting results have been reported about the performance of the zirconium oxide ceramic femoral head, but our findings suggest that it should not be used with a polymethylmethacrylate acetabular component. Hylamer has already been withdrawn from the market.

Low-friction arthroplasty of the hip using alumina ceramic and cross-linked polyethylene

We report the results of our continued review of 11 total hip arthroplasties using 22.225 mm alumina ceramic femoral heads on a Charnley flanged stem, articulating with chemically cross-linked polyethylene. There was an initial bedding-in of up to 0.41 mm at the articular surface in the first two years. This had not progressed further, at a minimum follow-up of 15 years. Radiographically no femoral or acetabular component showed loosening or osteolysis.

Comparison of Polyethylene Wear Associated with Cobalt-Chromium and Zirconia Heads After Total Hip Replacement&lt;sbt aid="1024890"&gt;A Prospective, Randomized Study&lt;/sbt&gt;

A ceramic femoral head is an alternative to a metal femoral head for the bearing surface of total hip arthroplasty. The purpose of this study was to compare polyethylene wear in patients who had undergone bilateral total hip arthroplasty with implants that differed only with regard to the material used for the femoral head: a zirconia head was used on one side, and a cobalt-chromium head was inserted on the contralateral side. A prospective, randomized study was performed to evaluate the outcomes in fifty-two patients who had undergone sequential bilateral primary total hip replacement. A zirconia head was used in one hip, and a cobalt-chromium head was used in the other. There were forty-eight men and four women; the mean age at the time of surgery was 44.2 years. The mean duration of follow-up was 7.1 years. Clinical and radiographic evaluations were performed preoperatively and at six weeks; three, six, and twelve months; and yearly postoperatively. Linear wear of the polyethylene liner was measured radiographically. Two femoral components with a zirconia head had aseptic loosening and were revised. The explanted heads were evaluated with use of interferometry, environmental scanning electron microscopy, and x-ray diffraction studies. The mean polyethylene wear rate was 0.08 mm/yr in association with the zirconia heads and 0.17 mm/yr in association with the cobalt-chromium heads (p = 0.004). The mean amount of volumetric polyethylene wear was 350.8 mm3 in association with the zirconia heads and 744.7 mm3 in association with the cobalt-chromium heads (p = 0.004). With regard to surface roughness, the Ra values of the two explanted zirconia heads were 15.87 and 17.35 nm and the Rpm values were 153.86 and 156.18 nm. Two identical zirconia heads that had not been implanted had Ra values of 5.31 and 5.48 nm and Rpm values of 65.27 and 66.35 nm. Four unimplanted cobalt-chromium heads that were identical to the ones implanted in this study had Ra values ranging between 25 and 50 nm and Rpm values ranging between 262.6 and 525.2 nm. Little phase transformation was noted in the two revised zirconia heads. The mean amount and rate of polyethylene wear were significantly lower in the hips with a zirconia head than they were in the hips with a cobalt-chromium head, presumably because the zirconia heads had a smoother articulating surface.

COMPARISON OF POLYETHYLENE WEAR ASSOCIATED WITH COBALT-CHROMIUM AND ZIRCONIA HEADS AFTER TOTAL HIP REPLACEMENT

Background: A ceramic femoral head is an alternative to a metal femoral head for the bearing surface of total hip arthroplasty. The purpose of this study was to compare polyethylene wear in patients who had undergone bilateral total hip arthroplasty with implants that differed only with regard to the material used for the femoral head: a zirconia head was used on one side, and a cobalt-chromium head was inserted on the contralateral side. Methods: A prospective, randomized study was performed to evaluate the outcomes in fifty-two patients who had undergone sequential bilateral primary total hip replacement. A zirconia head was used in one hip, and a cobalt-chromium head was used in the other. There were forty-eight men and four women; the mean age at the time of surgery was 44.2 years. The mean duration of follow-up was 7.1 years. Clinical and radiographic evaluations were performed preoperatively and at six weeks; three, six, and twelve months; and yearly postoperatively. Linear wear of the polyethylene liner was measured radiographically. Two femoral components with a zirconia head had aseptic loosening and were revised. The explanted heads were evaluated with use of interferometry, environmental scanning electron microscopy, and x-ray diffraction studies. Results: The mean polyethylene wear rate was 0.08 mm/yr in association with the zirconia heads and 0.17 mm/yr in association with the cobalt-chromium heads (p = 0.004). The mean amount of volumetric polyethylene wear was 350.8 mm3 in association with the zirconia heads and 744.7 mm3 in association with the cobalt-chromium heads (p = 0.004). With regard to surface roughness, the Ra values of the two explanted zirconia heads were 15.87 and 17.35 nm and the Rpm values were 153.86 and 156.18 nm. Two identical zirconia heads that had not been implanted had Ra values of 5.31 and 5.48 nm and Rpm values of 65.27 and 66.35 nm. Four unimplanted cobalt-chromium heads that were identical to the ones implanted in this study had Ra values ranging between 25 and 50 nm and Rpm values ranging between 262.6 and 525.2 nm. Little phase transformation was noted in the two revised zirconia heads. Conclusions: The mean amount and rate of polyethylene wear were significantly lower in the hips with a zirconia head than they were in the hips with a cobalt-chromium head, presumably because the zirconia heads had a smoother articulating surface. Level of Evidence: Therapeutic Level I. See Instructions to Authors for a complete description of levels of evidence.

Ceramic-on-ceramic versus ceramic-on-polyethylene bearings in total hip arthroplasty: Results of a multicenter prospective randomized study and update of modern ceramic total hip trials in the United States.

One reason why otherwise well-functioning total hip replacements have a finite service life is eventual aseptic loosening of the implants because of osteolysis induced by wear particles from the artificial bearing. Pain and osteolysis from wear debris can manifest even in the absence of aseptic loosening. Total hip replacements with ceramic-on-ceramic articulations have shown less wear both in vitro and in vivo. A randomized prospective clinical trial was conducted to compare the outcomes of ceramic-on-ceramic articulations to ceramic-on-polyethylene articulations. Two-year data are of interest because premature failures of ceramic femoral heads usually occur by this time interval. Of 500 patients enrolled in this trial, half received total hip replacements with alumina-on-alumina bearings, while the other half had ceramic-on-polyethylene bearings. At the two-year follow-up, 444 patients (217 study group and 227 control group) were available for review. The clinical and radiographic outcomes between the groups were comparable, and reflected the typical results of primary total hip replacements. No complications related to spontaneous failures of the ceramic bearings were observed at this early follow-up period. Further follow-up is needed to confirm these findings over the long-term, but the short-term safety of alumina ceramic bearings in hip replacements reported in other recent reports is further validated by our findings. (Hip International 2005; 15: 129-35).

Comparison of wear of ultra high molecular weight polyethylene acetabular cups against alumina ceramic and chromium nitride coated femoral heads

Over 80% of artificial hip joints utilise polyethylene acetabular cups articulating on metal or ceramic femoral heads. Alumina ceramic heads have previously been shown to reduce polyethylene wear. However, there are concerns about the brittle nature of ceramics and this places design constraints on neck length and head size. It is therefore of interest, to investigate ceramic-like coatings on metallic heads. The aim of this study was to compare the wear of polyethylene against alumina ceramic and chromium nitride (CrN) coated CoCr femoral heads in a hip joint simulator. Three 28-mm diameter Biolox™ Forte alumina ceramic heads and three CrN coated CoCr heads were articulated against UHMWPE GUR 1020 GVF (gamma irradiated in a vacuum foil pack), acetabular cups in the Leeds II hip joint simulator. The CrN heads were coated at Ionbond Limited using arc evaporative physical vapour deposition. The wear of polyethylene against alumina ceramic was 17 mm 3/million cycles and against CrN was 23 mm 3/million cycles. The difference was not statistically significant. Deliberate scratching of the femoral heads after 5 million cycles did not alter the wear rate. The coated heads had a slightly higher surface roughness and a higher contact angle than the ceramic heads. The contribution of both factors to the wear rate is currently being investigated.

Surface Roughness of Ceramic Femoral Heads After in Vivo Transfer of Metal

A dark metallic-appearing smear, resembling a lead pencil mark, may be seen on a ceramic femoral head component at revision total hip arthroplasty. The purpose of this study was to investigate the hypothesis that such a mark on a retrieved ceramic femoral head is associated with increased surface roughness of the head and increased polyethylene liner wear in total hip replacement. Fifteen ceramic prosthetic femoral heads retrieved from fifteen patients at revision arthroplasty were examined in this study. Thirteen heads had been in vivo for an average of 10.8 years (range, 7.8 to 14.2 years). The remaining two heads had been in vivo for less than one month. The surface roughness characteristics of the explanted ceramic heads, the linear wear of the polyethylene liner, and the patient activity levels after the primary replacement and before the revision were determined. Four of the thirteen ceramic heads that had been in vivo for >/=7.8 years had severe smears (>6% of the surface area), and the remaining nine heads had slight smears (<6% of the surface area). The two heads that had been in vivo less than one month had severe smears. The mean Ra and Rpm, the values for surface roughness, were 44.95 nm and 571.15 nm, respectively, in the hips with slightly smeared regions and 180.77 nm and 1245.88 nm, respectively, in the hips with severely smeared regions (p = 0.002). The mean linear liner wear rate was 0.10 mm/yr in the hips with slightly smeared heads and 0.19 mm/yr in the hips with severely smeared heads (p = 0.002). The activity score for all patients was 5 or 6 points on a 6-point scale. The results of this study confirm the hypothesis that a visual dark metallic-appearing smear on a ceramic femoral head correlates with increased surface roughness of the head and increased polyethylene wear. These findings imply that contact of a ceramic femoral head with a metallic material, such as may occur with femoral head reduction or dislocation of a total hip replacement, is best avoided to prevent this metallic smear phenomenon.

Ceramic-on-ceramic versus ceramic-on-polyethylene bearings in total hip arthroplasty: Results of a multicenter prospective randomized study and update of modern ceramic total hip trials in the United States

One reason why otherwise well-functioning total hip replacements have a finite service life is eventual aseptic loosening of the implants because of osteolysis induced by wear particles from the artificial bearing. Pain and osteolysis from wear debris can manifest even in the absence of aseptic loosening. Total hip replacements with ceramic-on-ceramic articulations have shown less wear both in vitro and in vivo. A randomized prospective clinical trial was conducted to compare the outcomes of ceramic-on-ceramic articulations to ceramic-on-polyethylene articulations. Two-year data are of interest because premature failures of ceramic femoral heads usually occur by this time interval. Of 500 patients enrolled in this trial, half received total hip replacements with alumina-on-alumina bearings, while the other half had ceramic-on-polyethylene bearings. At the two-year follow-up, 444 patients (217 study group and 227 control group) were available for review. The clinical and radiographic outcomes between the groups were comparable, and reflected the typical results of primary total hip replacements. No complications related to spontaneous failures of the ceramic bearings were observed at this early follow-up period. Further follow-up is needed to confirm these findings over the long-term, but the short-term safety of alumina ceramic bearings in hip replacements reported in other recent reports is further validated by our findings. (Hip International 2005; 15: 129-35).

The Pros and Cons of Polyethylene Sterilization with Gamma Irradiation

This retrospective study evaluated the implant, patient and surgical factors associated with polyethylene wear for one type of porous-coated hemispheric total hip arthroplasty cup. Radiographic wear measurements among 567 Duraloc cups (512 patients) revealed that liners sterilized by gamma-irradiation wore 0.085 mm/year less than those that were sterilized by gas-plasma, a noncross-linking chemical surface treatment. The substantially decreased wear rate associated with gamma-irradiation was attributed to sterilization-induced polyethylene cross-linking. Shelf-aging adversely affected liners that were gamma irradiated in air. On average, highly crystalline Hylamer liners showed a 0.064 mm/year increase in wear rates for each year of shelf storage after terminal sterilization with gamma-irradiation in air. Among conventional Enduron liners, the effect of shelf aging after gamma-irradiation in air was more modest, increasing wear rates by 0.014 mm/year for each year of shelf storage. Because Hylamer's wear performance degraded at about five times the rate of Enduron's, the improved wear resistance associated with gamma-irradiation in air would be lost after 1.3 years of shelf aging for Hylamer compared with 6.1 years for Enduron. For every additional year of age at the time of surgery, the wear rate decreased by 0.003 mm/year. Increased body mass index, a preoperative diagnosis of inflammatory arthritis, and a ceramic femoral head also were associated with decreased wear rates.