One concern about the fixation of HA-coated implants is the possible disintegration of the surface, with the migration of HA granules into the joint space, producing third-body wear. We report a study of six revisions of HA-coated polyethylene RM cups at 9 to 14 years after successful primary arthroplasty. In all six hips, we found HA granules embedded in the articulating surface of the polyethylene, with abrasive wear of the cup and the metal femoral head. The cup had loosened in four hips and three showed severe osteolysis of the proximal femur. Third-body wear due to HA particles from implant coating may produce severe clinical problems with few early warning signs. Further clinical, radiological and histological observations are needed to determine the possible incidence of this late complication in the various types of coating of a variety of substrates

Introduction: Polyethylene wear debris is the main contributing factor that leads to aseptic loosening and osteolysis. The main objective of this study was to evaluate the role of hydroxyapatite (HA) in third-body polyethylene wear in total hip arthroplasty. Materials: 199 primary cementless THA’s (174 patients) performed by a single surgeon were enrolled in a prospective randomized study comprising hydroxyapatite and non-hydroxyapatite coated femoral implants. The femoral component had metaphyseal-diaphyseal fit design with proximal plasma sprayed titanium circumferential porous coating. The hydroxyapatite coating was 50 – 75 micrometers over the porous surface with the components of identical design. The acetabular component was plasma sprayed titanium porous coated shell without hydroxyapatite. T he polyethylene liners were machined molded from ram extruded Hi-fax 1900H polyethylene resin gamma-sterilized in argon (inert) gas. Clinical and Radiographic evaluation was performed employing HSS scores and Engh criteria. Results: At a mean follow-up of 5 years, the radiographs of 83 HA and 73 Non-HA hips were evaluated by two independent observers utilizing computer-assisted wear analysis on digitized standardized radiographs described by Martell et al (1997). The radiographs were also evaluated for osteolysis or aseptic loosening. The mean linear wear rate in HA group was 0.19mm/yr and in the non-HA group was 0.21mm/yr, which was not significant (p> 0.05). There was no case of osteolysis or aseptic loosening of any component. Both groups had comparable outcomes in terms of HSS scores, walking ability and sports participation. Discussion: This study has attempted to demonstrate through an appropriately controlled in vivo study that hydroxyapatite does not play a significant role in third-body polyethylene wear in THA at a mean follow-up of five years. The concern of three-body wear with hydroxyapatite coating is no greater than porous coated cementless implants

Introduction: Polyethylene wear debris is the main contributing factor that leads to aseptic loosening and osteolysis. The main objective of this study was to evaluate the role of hydroxyapatite (HA) in third-body polyethylene wear in total hip arthroplasty. Materials: 199 primary cementless THA’s (174 patients) performed by a single surgeon were enrolled in a prospective randomized study comprising Hydroxyapatite and non-hydroxyapatite coated femoral implants. The femoral component had metaphyseal-diaphyseal fit design with proximal plasma sprayed titanium circumferential porous coating. The hydroxyapatite coating was 50 – 75 micrometers over the porous surface with the components of identical design. The acetabular component was plasma sprayed titanium porous coated shell without hydroxyapatite

Between 1995 and 1998, eighty revision total knee arthroplasties were done for the primary reason of advanced polyethylene wear. The primary arthroplasties prosthesis that failed included thirty-four mobile bearing knees and forty-six fixed bearing knees. In thirty-four Low Contact Stress (LCS) mobile bearing knees, osteolysis was identified intraoperatively in sixteen knees (forty-seven per cent). There were varying of fixation methods included nine cemented, four cementless and three hybrids. In forty-six fixed bearing knees, osteolysis was identified intraoperatively in six knees (thirteen per cent). The fixation methods of prostheses included two cemented and four cementless. The incidence of osteolysis was statistically significant difference between the mobile bearing and fixed bearing knees (p< 0.02).

Both scattering electron microscope (SEM) and light scattering analysis were used to examine the UHMWPE wear debris collected from tissue sample. The particle size analyzed by light-scattering is coincident with the measurement by SEM. The major type of wear debris extracted from failed knee prostheses is granular shape. There are more granular wear debris appear in the mobile bearing knees than in the fixed bearing knees. The particle size of UHMWPE wear debris with osteolysis was significantly smaller than that without osteolysis. The high rate of osteolytic lesions in mobile bearing knee (LCS) is well illustrated in our result that a lot of fine UHMWPE wear debris generated in the Low Contact Stress knee. The result also illustrates that there is no relationship between fixation methods and the third body wear that associate with osteolysis.

Aims. The aims of this study were to evaluate wear on the surface of cobalt-chromium (CoCr) femoral components used in total knee arthroplasty (TKA) and compare the wear of these components with that of ceramic femoral components. Methods. Optical profilometry was used to evaluate surface roughness and to examine the features created by the wear process in a knee wear simulator. We developed a method of measuring surface changes on five CoCr femoral components and quantifying the loss of material from the articular surface during the wear process. We also examined the articular surface of three ceramic femoral components from a previous test for evidence of surface damage, and compared it with that of CoCr components. Results. We found that the surface roughness of CoCr components rapidly increased during the first 1,000 wear cycles, then reached a steady state, but material loss from the surface continued at a rate of 1,778,000 μm. 3. per million cycles as carbides were removed from its matrix. These carbides formed third-body wear particles, leading to the formation of new scratches even as older scratches were worn away. In contrast, no scratching, loss of material, or other surface damage, when evaluated with one nanometer resolution, was found on the surface of the ceramic components after a 15 M wear cycle test. Conclusion. This study showed wear and loss of CoCr material from scratching and microabrasive wear in TKA. The material loss from the surface continued in a linear relationship with increasing cycles. We also found the absence of scratching and roughening of ceramic femoral components in simulated wear, suggesting an advantage in wear rate and avoiding metal sensitivity. This may have implications in the management of persistent pain after TKA. Cite this article: Bone Joint J 2021;103-B(6 Supple A):94–101

Objectives. Third-body wear is believed to be one trigger for adverse results with metal-on-metal (MOM) bearings. Impingement and subluxation may release metal particles from MOM replacements. We therefore challenged MOM bearings with relevant debris types of cobalt–chrome alloy (CoCr), titanium alloy (Ti6Al4V) and polymethylmethacrylate bone cement (PMMA). Methods. Cement flakes (PMMA), CoCr and Ti6Al4V particles (size range 5 µm to 400 µm) were run in a MOM wear simulation. Debris allotments (5 mg) were inserted at ten intervals during the five million cycle (5 Mc) test. . Results. In a clean test phase (0 Mc to 0.8 Mc), lubricants retained their yellow colour. Addition of metal particles at 0.8 Mc turned lubricants black within the first hour of the test and remained so for the duration, while PMMA particles did not change the colour of the lubricant. Rates of wear with PMMA, CoCr and Ti6Al4V debris averaged 0.3 mm. 3. /Mc, 4.1Â mm. 3. /Mc and 6.4 mm. 3. /Mc, respectively. . Conclusions. Metal particles turned simulator lubricants black with rates of wear of MOM bearings an order of magnitude higher than with control PMMA particles. This appeared to model the findings of black, periarticular joint tissues and high CoCr wear in failed MOM replacements. The amount of wear debris produced during a 500 000-cycle interval of gait was 30 to 50 times greater than the weight of triggering particle allotment, indicating that MOM bearings were extremely sensitive to third-body wear. Cite this article: Bone Joint Res 2015;4:29–37

Introduction. The release of metal debris and ions has raised concerns in joint arthroplasty. In THA metal debris and ions can be generated by wear of metal-on-metal bearing surfaces and corrosion at modular taper interfaces, currently understood to be mechanically assisted crevice corrosion (MACC) [1]. More recently, inflammatory-cell induced corrosion (ICIC) has been identified as a possible source of metal debris and/or ions [2]. Although MACC has been shown to occur at modular junctions in TKA, little is known about the prevalence of other sources. The purpose of this study was to determine the sources of metallic debris and ion release in long-term implanted (in vivo > 15y) TKA femoral components. Specific attention was paid to instances of ICIC as well as damage at the implant-bone interface. Methods. 1873 retrieved TKA components were collected from 2002–2013 as part of a multi-center, IRB-approved retrieval program. Of these, 52 CoCr femoral condyles were identified as long term TKA (Average: 17.9±2.8y). These components were predominantly revised for loosening, PE wear and instability. 40/52 of the components were primary surgeries. Components were examined using optical microscopy to confirm the presence of 5 damage mechanisms (polyethylene failure, MACC corrosion of modular tapers, corrosion damage between cement and backside, third-body wear, and ICIC). Third-body wear was evaluated using a semi-quantitative scoring method based on the percentage of damaged area. A score of 1 had minimal damage and a score of 4 corresponded to severe damage. Polyethylene components were scored using the Hood method and CoCr components were scored similarly to quantify metal wear. The total area damaged by ICIC was quantified using photogrammetry. Images were taken using a digital SLR with a calibrated ruler in the same focal plane. Using known pixel dimensions, the ICIC damaged area was calculated. Results. Surface damage indicative of corrosion and/or CoCr debris release was identified in 92% (n=48) of the components. Third-body wear was the most prevalent damage mechanism identified in 77% (n=40/52; Figure 1) of these components. ICIC was identified in 38% (n=20/52, figure 2) of the components. The polyethylene damage scores were predominantly a score of 4 out of a maximum score of 4 (89%). The corresponding femoral components had moderate to severe damage scores, with 39% with a score of 2, 37% scoring 3 and 22% scoring 4 out of a maximum score of 4. The total ICIC damaged area was an average of 0.11 ± 0.12 mm. 2. (Range: 0.01–0.46mm. 2. ). Discussion. In this study, we sought to identify mechanisms that could lead to the release of CoCr debris/ions in TKA. Five different mechanisms of potential metal release were observed. The most prevalent were third-body wear and ICIC damage. However the clinical implications remain unclear for several mechanisms because none of the devices were revised due to adverse local tissue reactions or biologic reactions to CoCr. Although we documented the prevalence of each damage mechanism, the quantity of metal removal was not investigated, warranting future studies

Introduction. Today TKR is considered one of the most successful operative procedures in orthopedic surgery. Nevertheless, failure rates of 2 – 10% depending on the length of the study and the design are still reported. This provides evidence for further development in knee arthroplasty. Particularly the oxide ceramics used now in THA show major advantages due to their excellent tribological properties, their significantly reduced third-body wear as well as their high corrosion resistance. A further advantage of ceramic materials is their potential use in patients with metal allergy. Metallic wear induces immunological reactions resulting in hypersensitivity, pain, osteolysis and implant loosening. The purpose of our study was to examine the safety of the tibial component of a novel all-ceramic TKR. Materials and Methods. We tested the tibial components of the primary knee implant BPK-S Integration Ceramic. Both the tibial and the femoral component consist of BIOLOX®delta ceramic The standards ISO 14879-1 and ASTM F1800-07 describe the test set-up for the experimental fatigue strength testing of tibial components from knee implants. We conducted the testing with a significantly increased maximum load of 5,300 N (900 N are required). A final burst strength test was carried out after the fatigue load testing in the same embedding and with the same test set-up. Results. No specimen failed during fatigue load testing. The subsequent post-fatigue burst strength testing showed a maximum strength against fracture of at least 9.7 kN for size 3 and at least 12.1 kN for size 6. Discussion. The good results of the strength testing of the tibial component of the BPK-S Integration Ceramic tibial plateau supported the good initial clinical outcome without any implant specific complications of this knee design. Further clinical studies have to show if this design fulfills the high expectations over long periods of time

We carried out a histological study of a proximally hydroxyapatite (HA)-coated femoral component, retrieved after 9.5 years of good function. The HA coating had completely degraded. Bone was in direct contact with the titanium surface in all the areas which had been coated, with no interposing fibrous tissue. There were no signs of particles, third-body wear, adverse tissue reactions or osteolysis. Bone remodelling was evident by the presence of resorption lacunae; tetracycline labelling showed bone laid down six years after implantation. The loss of the HA-coating had no negative effect on the osseo-integration of the stem. We conclude that the HA coating contributes to the fixation of the implant and that its degradation does not adversely affect the long-term fixation

There are several techniques for the accurate measurement of the migration of components after arthroplasty some of which require the operative placement of tantalum balls. We have reviewed the position and migration of these markers in 64 patients after total hip arthroplasty. In 40% of cases, one or more balls was seen to be outside the proximal femur on the postoperative radiograph, although all were considered to be within the bone at operation. In two hips, one ball appeared to have migrated towards the joint, although none was seen within the joint. Misplacement was not related to the experience of the surgeon or the operative approach. Migration analysis which necessitates the insertion of tantalum balls requires careful technique to avoid a potential source of third-body wear. It should probably be used only for research in small series of patients

Our aim was to determine whether tantalum markers improved the accuracy and/or precision of methods for the measurement of migration in total hip replacement based on conventional measurements without mathematical correction of the data, and with Ein Bild Roentgen Analyse – Femoral Component Analysis (EBRA-FCA) which allows a computerised correction. Three observers independently analysed 13 series of roentgen-stereophotogrammetric-analysis (RSA)-compatible radiographs (88). Data were obtained from conventional measurements, EBRA-FCA and the RSA method and all the results were compared with the RSA data. Radiological evaluation was also used to quantify in how many radiographs the intraosseous position of the bone markers had been simulated. The results showed that tantalum markers improve reliability whereas they do not affect accuracy for conventional measurements and for EBRA-FCA. Because of the danger of third-body wear their implantation should be avoided unless they are an integral part of the method

We examined 86 polyethylene inserts, retrieved from total and unicompartmental knee prostheses after an average of 39.5 months in situ, grading them from 0 to 3 for seven modes of polyethylene degradation. Severe wear, with delamination or deformation, was observed in 51% of the implants, and was associated with time in situ, lack of congruency, thin polyethylene, third-body wear debris, and heat-pressed polyethylene. Significant under-surface cold flow was identified in some areas of unsupported polyethylene, and was associated with delamination in the load-bearing areas of thin inserts above screw holes in the underlying metal tray. We recommend the use of thicker polyethylene inserts, particularly in young, active patients and in designs with screw holes in the tibial baseplate. Thin polyethylene inserts which are at risk for accelerated wear and premature failure should be monitored radiographically at annual intervals

With the plasma–spray technique of applying a hydrox-ylapatite (HA) coating bone ingrowth can be enhanced and early migration of hip prostheses reduced. The significance of coating resorption is controversial. In this study the bone growth and the degradation of the HA coatings were evaluated and compared by SEM. Premature loosening was identified in four cups with an Ha coating over a porous-coated surface 3 years post-operatively.The Ha coating has a thickness of up to 50 μm. The cup specimens were soaked in 6% sodium hypochlorite to render them anorganic, dehydrated, and sputter-coated with gold-palladium. Secondary electron images of all specimens were obtained by field emission SEM (Zeiss:DSM.962). Ultrastructural analysis showed that all porous-coated Ha-coated cups had bridges of lamellar bone in direct contact with the implant surface (30% bone in-on growth). Different types of coating degradation were observed. Delamination between the coating and implant surface releases numerous particles or fragments; the resorption by osteoclasts of the amorphous phase was shown to expose the crystalline phase of the coating grains. This study suggests that resorption disintegrates the Ha coating and reduces the bonding strength between implant and bone and the strength of the coating-implant interface, which might lead to implant loosening,coating delamination and acceleration of third-body wear processes

Revision of fractured ceramic-on-ceramic total hip replacements with a cobalt-chromium (CoCr) alloy-on-polyethylene articulation can facilitate metallosis and require further expensive revision surgery [1–3]. In the present study, a fifty-two year old male patient suffered from fatal cardiomyopathy after undergoing revision total hip arthroplasty. The patient had received a polyethylene-ceramic acetabular liner and a ceramic femoral head as his primary total hip replacement. The polyethylene-ceramic sandwich acetabular liner fractured in vivo after 58 months and the patient underwent his first revision surgery where he received a Vitamin E stabilized acetabular Polyethylene (PE) liner and a CoCr alloy femoral head with documented synovectomy at that time. After 15 months, the patient was admitted to hospital in cardiogenic shock, with retrieval of the bearing components. Before the second revision surgery, peak serum cobalt levels measured 6,521 μg/L, 78-times greater than serum cobalt levels of 83μg/L associated with cobalt poisoning [4]. Serum titanium levels found in the patient measured 17.5 μg/L) normal, healthy range 0–1.4 μg/L). The retrieved CoCr alloy femoral head had lost a total of 28.3g (24% or an estimated amount of 102 × 10. −9. wear particles (∼2 μm diameter) [1]) within 16 months of in vivo service. Despite initiating a cobalt chelating therapy, the patients' cardiac left ventricular ejection fraction remained reduced at 6%. This was followed by multi-organ failure, and ultimately the patient passed away shortly after being taken off life support. Embedded ceramic particles were found on the backside and articular surfaces of the Vitamin E-stabilized PE acetabular liner. Evidence of fretting wear on the titanium (Ti) alloy acetabular shell was present, possibly explaining the increased serum Ti levels. Scanning electron microscopy and energy dispersive X-ray analyses confirmed Ti alloy transfer on the embedded ceramic particles on the backside PE liner surface and CoCr alloy transfer on the embedded ceramic particles on the articular PE liner surface. A fractured ceramic-on-ceramic total hip replacement should not be revised to a CoCr alloy-on-polyethylene articulation irrespective of concurrent synovectomy [5] as it can cause severe, third-body wear to the CoCr alloy femoral head that can lead to metallosis with fatal, systemic consequences

Summary. The 80% porous structure of trabecular metal allows for bone ingrowth in more than 90% of the available surface. The Nexgen LPS Uncemented Knee using a trabecular metal tibial component has performed well at minimum of 5 years’ follow-up. Introduction. Total Knee Arthroplasty prostheses most frequently used in today's practice have cemented components. These have shown excellent clinical results. The fixation can however weaken with time, and cement debris within the articulation can lead to accelerated wear. Cementless implants are less commonly used, but some have also shown good long-term clinical results. The potential advantages of cementless implants are retention of bone stock, less chance of third-body wear due to the absence of cement, shorter operative time, and easier treatment of periprosthetic fractures. The posterior stabilised knee replacement has been said to increase tangential shear stresses on the tibial component and increases contact stresses on the cam and post mechanism hence the great debate of cruciate retaining or cruciate sacrificing implants. Objectives. We report the results of a prospective cohort of consecutive primary total knee arthroplasties using an uncemented posterior stabilised prosthesis using a trabecular metal (tantalum) tibial component at a minimum 5-year follow-up. Methods. Prospective 5 year follow-up of patients undergone an uncemented posterior stabilised total knee replacement using a trabecular metal tibial component (NexgenLPS). Clinical examination, Oxford knee score, Knee society score, SF12 and radiological evaluation undertaken at review. Results. 81 patients, 45 female, 36 male. Left 31, Right 50. Mean age 74.3 yrs range (51–90). SF12, mean: 31.8 range (25–37). Oxford Knee Score Pre-op Mean 20.1 range (9–36) Post op: Mean 32.1 range (9–48). Knee Society score. Pain Mean 91.8; range (60–100). Functional score mean 76.2; range (30–100). Mean Range of movement 110.5 degrees range (90–125). No evidence of loosening at 5 yrs. No deep infection. No Revisions. Conclusion. Although there are a variety of methods of achieving satisfactory initial fixation in cementless components, trabecular metal has an advantage owing to its cellular structure resembling bone. The 80% porous structure of trabecular metal allows for bone ingrowth in more than 90% of the available surface. The Nexgen LPS Uncemented Knee using a trabecular metal tibial component used in this series has shown no evidence of loosening at a minimum of 5 years’ follow-up and the prosthesis as a whole has performed very well clinically. Its early results are comparable to those prostheses most commonly used as reported by the arthroplasty registers. The longer term results from this prosthesis are awaited with interest

Introduction. From a tribological point of view and clinical experience, a ceramic-on-ceramic bearing represents the best treatment option after rare cases of ceramic component fracture in total hip arthroplasty (THA). Fractured ceramic components potentially leave small ceramic fragments in the joint capsule which might become embedded in PE acetabular liners. Purpose. This in vitro study compared for the first time the wear behaviour of femoral ball heads made of ceramic and metal tested with PE liners in the presence of ceramic third-body debris. The contamination of the test environment with third-body ceramic debris, insertion of ceramic fragments into the PE liners and implementation of continuous subluxation simulated a worst-case scenario after revision of a fractured ceramic component. Materials and Methods. Ceramic femoral ball heads (ϕ 32 mm) made of alumina matrix composite (AMC; BIOLOX® delta, CeramTec, Germany) were tested in combination with PE and cross-linked liners and compared to metal femoral ball heads (CoCrMo) of the same diameter. All PE liners were fixed into Ti-6Al-4V metal shells by conical fixation as intended for clinical use. The tests were performed based on ISO 14242-1 utilizing a hip simulator (EndoLab, Germany). Alumina ceramic debris (BIOLOX® forte, CeramTec, Germany) of about 2 mm diameter (maximum 5 mm) were inserted into the PE liners in predefined specific points corresponding to the main load transfer area before the test. The acetabular liners were tested at an inclination of 45° in the medial-lateral plane with the specimens placed in an anatomically correct position. During the test, additional alumina ceramic debris was introduced into the articulation area as a part of the test fluid (calf serum) used in the simulator test chambers. All specimens were tested up to 5 million cycles. Damages to the surfaces of the materials were assessed visually. The wear of the femoral ball heads was measured gravimetrically. Results. High wear rates were found for metal femoral ball heads, being 1,010 times higher when compared to ceramic femoral ball heads tested with XPE liners and 560 times higher when compared to ceramic femoral ball heads tested with conventional PE liners. The conventional and crosslinked PE liners used in combination with metal femoral ball heads clearly exhibited a scratched surface, whereas the surface of the liners tested with ceramic femoral ball heads exhibited significantly less scratching. Discussion and Conclusion. This study demonstrates that apart from the recommended ceramic-on-ceramic option also ceramic-on-PE and ceramic-on-crosslinked PE bearing couples may be a viable treatment option after fracture of a ceramic component. The use of a ceramic femoral ball head after fracture of a ceramic articulation component minimizes wear and wear-related complications caused by third-body wear. Based on the results of this in vitro study and clinical findings, the use of a metal femoral ball head in articulation with any PE liner after a ceramic fracture is contraindicated

Poly-L-lactic acid (PLLA) is characterized by its biocompatibility and biodegradability, and is used clinically. In our hospital, we started to use PLLA screws instead of metallic or ceramic screws in the fixation of acetabular bone grafts in total hip arthroplasty (THA) in 1990, because there were concerns about the use of rigid and nonbioabsorble screws, which might contribute to the absorption of the grafted bone and induce metallosis or third-body wear when breakage of the screws occurs. The purpose of this study was to review a series of cemented THA for dysplasia, with structural autograft fixed with PLLA screws. We focused on the survival rate of the acetabular component and radiological change of the grafted bone–socket interface. This study included 104 consecutive cemented total hip arthroplasties (80 patients) performed between July 1990 and December 1995 in our hospital. All patients were followed over 10 years and reviewed retrospectively. The grafted bone trimmed from the excised femoral head was fixed rigidly with 1 or 2 PLLA screws (cancellous lag screws 6.5 mm in bore diameter and 4.1 mm in grove diameter) (Fixsorb; Takiron Co., Ltd., Osaka, Japan). X-ray photographs taken just after the primary operation showed an obscure but still visible radiolu-cent region corresponding to the inserted PLLA screws in many cases. However, X-ray photographs at the final follow-up showed an unclear radiolucent zone at the sites of the PLLA screws, and the osteosclerotic line surrounding the site where the radiolucent zone had been found was confirmed in only 4 cases. Bone union was confirmed radiologically at the grafted site in every case, and there were no cases of early collapse or extravasation of the grafted bone. No positive resorption of the grafted bone was observed in any case. Kaplan–Meier survivorship analysis of socket revision, radiological loosening of the socket, and the appearance of a radiolucent line > 1 mm in the graft–socket interface as the endpoints indicated survival rates of 99%, 97.1%, and 63.5% at 10 years, and 96.6%, 90.2%, and 56.1% at 15 years, respectively. The results of this study indicated that PLLA screws are safe and useful for the fixation of acetabular bone graft concomitant to cemented THA with a careful rehabilitation program. However, because of concern about the mechanical insufficiency of the PLLA screws for THA with an early weight-bearing rehabilitation program, we have used mechanically stronger and bioabsorbable screws made of forged composites of hydroxyapatite and PLLA since 2003

Aseptic loosening induced by wear debris of polyethylene (PE) is the most common cause of long-term total hip arthroplasty failure. In the previous studies, we reported that the protruding contour and surface morphology of metallic femoral head brought an increase of PE wear. Alumina ceramics is advantageous (neutral shape and smooth surface) for precision machining compared with metal materials, because hardness of ceramics is higher than that of metal materials. In this study, we measured the roundness and the roughness of retrieved alumina ceramic and metallic heads, aiming to evaluate the change of surface morphology of those heads in vivo. Fourteen retrieved alumina ceramic femoral heads (Kyocera Corp., currently Japan Medical Materials Corp.) were examined: ten femoral heads were made of small grain-size alumina ceramic (SG-alumina; mean grain size is 3.4 um) with a diameter of 28 mm, with clinical use for 16–28 years (mean 22 years) and four femoral head was made of extra-small-grain size alumina ceramic (XSG-alumina; mean grain size is 1.3 um) with a diameter of 26 mm, with clinical use for 14–19 years (mean 16 years). Six retrieved metallic femoral heads with average clinical use for 12–28 years (mean 18 years) were examined: a diameter of from 22 to 32 mm (e.g. Zimmer Inc., Stryker Corp.) The roundness of the retrieved femoral heads was measured by a contour tracer. The surface roughness in the contact area and the non-contact area of the retrieved femoral heads was measured by a surface roughness tester. Out-of-roundness of SG-alumina and XSG-alumina heads was 0.15 um and 0.19 um, respectively. In contrast, that of metal heads was 2.43 um, and the profiles were in wide distortion compared with both alumina heads. The surface roughness was 0.012 um in the contact area, and 0.009 um in the non-contact area of retrieved SG-alumina heads. The surface roughness in the contact area, 0.007 um, of XSG-alumina was slightly higher than that in the non-contact area, 0.003 um, and the both area of XSG-alumina represent lower value than SG-alumina, with all alumina heads having a reentrant surface profile. In contrast, the surface roughness of metallic heads was in a range of 0.003–0.053 um and several heads showed the protrusion surface profile. In this retrieval study, the roundness and the roughness of both alumina ceramic femoral heads after long-term clinical use were low and stable compared with metallic heads. And also, the surface roughness increased in the order of XSG-alumina < SG-alumina < metallic head. The alumina ceramic femoral head showed the reentrant surface whereas the metallic head showed the protruding surface. When third-body wear occurs during the clinical use, generally reentrant form may occur on the ceramic surface whereas protrusion form may occur on the metallic surface. We have good clinical results more than 20 years using the SG-alumina, and clinical results for a long term will be expected with XSG-alumina of improved microstructure