The leading indication for revision total hip arthroplasty (THA) remains aseptic loosening owing to wear. The younger, more active patients currently undergoing THA present unprecedented demands on the bearings. Ceramic-on-ceramic (CoC) bearings have consistently shown the lowest rates of wear. The recent advances, especially involving alumina/zirconia composite ceramic, have led to substantial improvements and good results in vitro. Alumina/zirconia composite ceramics are extremely hard, scratch resistant and biocompatible. They offer a low co-efficient of friction and superior lubrication and lower rates of wear compared with other bearings. The major disadvantage is the risk of fracture of the ceramic. The new composite ceramic has reduced the risk of fracture of the femoral head to 0.002%. The risk of fracture of the liner is slightly higher (0.02%). Assuming that the components are introduced without impingement, CoC bearings have major advantages over other bearings. Owing to the superior hardness, they produce less third body wear and are less vulnerable to intra-operative damage. The improved tribology means that CoC bearings are an excellent choice for young, active patients requiring THA. Cite this article: Bone Joint J 2016;98-B(1 Suppl A):14–17

Introduction: Ceramics appear to be good material for bearing surfaces due to their extreme hardness. We present the follow up results on 726 Total Hip Replacements using ceramics done in an institution over 19 years. Patients and methods: This is a single surgeon series of 836 total hip replacements using ceramic as a bearing surface, performed since 1981. 283 of these were ceramic on ceramic whereas 408 were ceramic on polyethylene, most inserted without cement. 726 (86.9%) of these patients were either examined (546) or assessed with a questionnaire (149). 31 patients had died and their dates of death were taken as the point in time when their hips were surviving. These three groups are included in the analysis. 43 of the hips were revised. A survivorship analysis – using the life table technique – of the two groups was performed using revision as the end point. Results: 31 total ceramics, and 12 ceramic-on-polyethylene hips required revision. The survivorship illustrated a superior performance of the ceramic-on-polyethylene implants. Discussion: The patients in the total ceramic group were considerably younger (average age 34.7) compared to the ceramic on polyethylene group (average age 59.2). Seven patients with failed implants from the ceramic-on-ceramic group had been subjected to previous surgery compared to only one in the other group. The majority of the ceramic-on-ceramic group had a primary pathology more likely to cause a distorted anatomy of the hip joint. In general the patients in the total ceramic group were at higher risk of failure for technical reasons. The follow up period – mean 9.23 years for the total ceramic group, and 8.22 years for the ceramic-on-polyethylene group – is relatively short, and future years will further clarify the situation

Purpose: Ceramic/ceramic bearing surfaces have the advantage of significantly decreased wear and high biocompatibility compared to CoCr/PE or ceramic/PE. The purpose of this randomized, controlled, multi-center, prospective study was to evaluate the clinical and roentgenographic results of 469 ceramic/ceramic versus 321 ceramic/PE THA at a 2 to 7 year follow-up. Methods: The ceramic/ceramic THA had a polished alumina femoral head articulating with a polished alumina acetabular liner seated into the metal acetabular shell designed to avoid any impingement of the ceramic liner on the femoral component. Evaluations were completed preoperatively, at 6 months and yearly postoperatively. Results: Mean age of the 790 patients was 59 years, with slightly more females. There were no significant demographic differences between the two groups. The main diagnoses were OA in 74% and osteonecrosis in 19%. Preoperatively the mean Harris Hip Score (HHS) and WOMAC scores were 44 and 41, respectively, and did not differ significantly between the two groups. At follow-up, the mean HHS was 93 for the ceramic/ ceramic THA and 93 for the ceramic/PE THA. The mean WOMAC scores showed no differences at follow-up. Roentgenographic analysis revealed one acetabular cup migration with a PE liner. One ceramic liner fractured upon insertion that was not properly positioned prior to impaction. Otherwise, there were no revisions or complications related to either bearing surface. Conclusions: This short-term study has demonstrated efficacy and safety of a ceramic/ceramic bearing surface compared to the standard ceramic/PE surface currently used in clinical practice, with no failures or complications related to the bearing surface. Further follow-up is indicated to determine the long-term outcome. Funding: Commerical funding. Funding Parties: Encore Orthopaedics

A standard is defined as something established by authority, custom, or general consent. Clearly that does not exist for ceramic on ceramic total hip replacement. A better question is: Is there any indication for a ceramic on ceramic total hip. The answer to that question should when possible be based on clinical outcome data including the value added (or not) with this more expansive technology. Ceramic on ceramic has been popularised based on its low wear. Is this clinically relevant? Probably not, based on currently available data. Both metal on highly crosslinked polyethylene and ceramic on highly crosslinked polyethylene have very low clinically documented wear rates with excellent outcomes in multiple studies. In addition, ceramic on ceramic bearings are more sensitive to implant position. Whereas polyethylene may tolerated edge loading and impingement, ceramic bearings are less likely to do so. Dislocation remains one of if not the top reason for early revision. Even with newer ceramics, there are still less options to fine tune hip stability with ceramic on ceramic bearing surfaces. When looking at the overall, risk of revision, Bozic et al concluded that hard bearings provided no benefit in terms of risk reduction of revision. Considering their higher cost, they questioned the use of these products especially in the 65 and older age group. Looking at the Australian Registry, the cumulative percent revision for ceramic-ceramic THA was 5.7% at 11 years compared to 5.1% for metal on crosslinked poly. The hazard ratio (adjusted for age and gender) was 1.09 in favor of ceramic on poly and the difference was highly significant (p=0.012). When one take into account the increased cost of ceramic on ceramic bearings, it is hard to make a case for ceramic on ceramic bearings. Any use of ceramic on ceramic bearings would have to be based on the hypothesis that in the long run in young active patients they may provide an advantage. This is a hypothesis with no data to support it currently

Squeaking in ceramic total hip joint replacements has become a controversial topic. This study aims to document the incidence of squeaking and other noise generation in a single surgeon series for ceramic on ceramic total hip joint replacements. Possible aetiological for squeaking causes are explored. All patients from public and private who received ceramic on ceramic total hip joint replacements (Stryker trident-accolade) from 2002 to 2007 were identified via the New Zealand Joint registry. Following ethics approval all patients were contacted for a phone interview to question as to whether they had noted any noise generation. Patients who demonstrated noise generation were reviewed in clinic for full history and examination. Data including age, sex, weight, primary diagnosis, head size and cup size were obtained from clinical notes. Post operative x-rays were reviewed to analyse cup abduction and version. Forty one ceramic total hip joint replacements in a total of thirty seven patients were reviewed via telephone interviews. Three patients complained of squeaking in the ceramic bearing while one patient complained of a grinding and one other of clicking. Two of the three who had recognised the squeaking were both able to reproduce the squeaking in the clinic room. The third patient was noted to have crepitus from anterior patello-femoral osteoarthritis. There was no statistical difference in age, weight, primary diagnosis or head size. In terms of abduction and version of the acetabular cups that squeaked, one had twenty seven degrees of ante-version and forty seven degrees of abduction and the other fifteen degrees of anteversion and thirty degrees of anteversion. Four cups lay outside the recommended fifteen-thirty five degrees of anteversion and thirty five-fifty five degrees of abduction yet showed no squeaking. Neither patient is troubled by the squeaking and neither would seek revision surgery. The incidence of squeaking in ceramic on ceramic total hip joint replacements appears to be around five percent with a similar number of patients experiencing other noises. The position of the acetabular cup does not appear to be the sole contributor to the noise and other aetiological causes need to be further investigated

Hallux rigidus is a common condition involving the first Metatarsophalyngeal (MTP) joint. Total joint arthroplasty is an acceptable modality of treatment. A number of different prosthesis have been used. Our study aims to evaluate the outcome of uncemented ceramic on ceramic (MOJE) prosthesis, in the treatment of painful hallux rigidus. Between March 2000 and June 2005, 38 patients (53 feet) with painful hallux rigidus were treated with uncemented ceramic on ceramic (MOJE) prosthesis. There were 30 female and 8 male patients. The hallux meta-tarsophalangeal-interphalangeal scoring scale, by the American Orthopaedic Foot and Ankle Society, was used to assess these patients, pre-operatively and at follow up. A total score of 100 is possible in a patient with no pain, full range of MTP joint movement and good alignment. The average follow up was for 34 months (range 12–68 months). Three revisions were carried out in three patients, 2 for deep infection, and 2 for persisting pain. Five patients showed radiological signs of osteolysis but had no symptoms. There was one late subluxation after 32 months. One patient developed a superficial infection, which was treated successfully. The average AOFAS score pre-operatively was 45, compared to 91 post-operatively (p< 0.05). 23 patients (36 feet) classed the outcome as excellent to good. Ten of the patients subjectively described the out come of the procedure as excellent. The preop range of movement (combined dorsiflex-ion and plantarflexion) was improved from a mean of 22 degrees to 68 degrees postoperatively. The ceramic/ceramic (MOJE) total arthroplasty gave excellent results in 77% of patients. The early outcome is encouraging. We ewcommend continued use of this prosthesis for painful hallux rigidus

Aim: Alumina ceramic on ceramic bearings have gained popularity in hip arthroplasty due to the properties of low wear, low friction and chemically inert wear debris. In a previous study, we reported the excellent clinical results of a series of cementless ceramic on ceramic primary total hip arthroplasties at a minimum of 5 years. We now present the follow up results at 10 years. Method: Between June 1997 and February 1999, 301 consecutive, primary cementless hip arthroplasties were performed on 283 patients in our unit. The mean age of the patients was 57.8 years, with 145 (51%) being female. All of the hips received the same implant: (Osteonic ABC cup and Secure-Fit or Secure-Fit Plus stem; Stryker Orthopaedics). A third generation alumina ceramic on ceramic bearing (Biolox Forte; CeramTec) was used for articulation in all cases. All the operations were performed through a posterior approach with enhanced posterior repair, and the post-operative protocols were the same for all the patients. The clinical and radiographic outcome at 10 years were analysed. Results: At 10 years, 7.3% had died of unrelated cause and 3% were revised. The average Harris Hip score was 94.3 points at the last follow up. Ninety six percent of patients scored an excellent or good result, with less than 3% have moderate residual pain. Radiographically, all patients assessed had evidence of stable bony ingrowth. There were nine revisions in all, four stem revisions due to periprosthetic fracture, one secondary to aseptic loosening and one to facilitate a femoral shortening osteotomy. There was one cup revision for psoas tendonitis and one for cup repositioning. This same patient subsequently underwent further revision due to acetabular osteolysis with metallosis and some ceramic wear. Overall, the survival rate of the implants was 96% at 10 years. The retrieved femoral heads showed a median wear rate of 0.2 cubic millimeters per year. Conclusions: Alumina ceramic on ceramic bearings in cementless primary total hip arthroplasty had been shown to have good survival rate at 10 years with good function, low wear rate and no adverse radiographic changes. The one case of osteolysis may be due to ceramic wear debris or may be due to metal wear debris from the neck to rim impingement

The purpose of this study is to analyze clinical and radiological results of total hip arthroplasty using the 3rd generation ceramic on ceramic articular surface. Between July 1999 and May 2005, 339 hips of 250 patients had primary cementless total hip arthroplasty with the 3rd generation ceramic on ceramic bearing implants. And 325 hips of 236 patients were followed up over 3 years. Male were 168 patients(237 hips) and female were 68 patients(88 hips). The mean age at the time of operation was 47.3(range, 25~76) years old and the mean follow up period was 62.4(range, 36~107.6) months. The preoperative diagnoses were osteonecrosis of the femoral head (ONFH) in 250 hips, secondary osteoarthritis in 55 hips(dysplasia in 35, infection sequalae in 12, LCP in 2, CDH in 2), hemophilic arthropathy in 9 hips, ankylosing spondylitis in 7 hips etc. We used Bicontact system(Aesculap, Germany) in 65 hips, Secur-FitTM(Stryker Howmedica Osteonics, USA) in 206 hips, Trilogy ABTM (Zimmer, USA) in 54 hips. Clinically, Harris Hip Score, thigh pain, squeaking and other complications were evaluated. Radiologically, the serial radiographs were analyzed. Clinically, the Harris hip score was improved from preoperative 66.0(19~91) to 96.2(58~100) at the last follow-up. Radiologically, there was no loosening of implants and visible wear and osteolysis. Heterotopic ossifications were noted in 5 cases. In complications, there was dislocation in one case, periprosthetic fracture in 2 cases and thigh pain in 9 cases. Intermittent squeaking sound has occurred in 8 cases(2.5%). Among these, one case of loud squeaking which happened after fall down had revision surgery. There was no infection and fracture of ceramic implant. Our midterm results of THA with the 3rd generation ceramic bearing system were very satisfactory and demonstrated that the 3rd generation ceramic bearings remain as an excellent bearing choice because of their superior wear characteristics. However, the results of this study suggests that the squeaking would be one of strong potential risk factors for failure of ceramic on ceramic total hip arthroplasty and we must be very cautious to prevent squeaking

Hydroxyapatite Ceramic Coated Hips (HAC) were first used in Sunderland, U.K. in May 1988. More than 1725 HAC hips have been inserted. There are 264 hips in 237 patients with ceramic/ceramic (alumina) bearings. These hips are inserted into patients with a 20+ year life expectancy. Their mean age is 50.5 years. All patients are assessed using the Harris Hip Score pre. and postoperatively. There are 14 patients with Harris Hip Scores of less than 80, but only 8 patients have problems attributable to HAC hip surgery. These include 1 patient with infection, 3 fractured ceramic acetabular liners, one broken ceramic head, 2 with aseptic loosening and 1 patient who chronically dislocated her hip. Amongst the indications were osteoarthritis 136, hip dysplasia 44, and ankylosing spondylitis 13. Twenty six had had previous childhood hip disorders, and 16 had rheumatoid arthritis. The series also includes 4 revisions from cemented hip replacement. The results have been rewarding. There are 1700+ HAC hips in the whole series. This sub group of 264 ceramic/ceramic HAC hips is small and follow up is relatively short. There have been few failures which could be attributed to the HA coated device. However, there are 4 broken ceramic components. Conclusion: Hydroxy Apatite bony bonding secures the implants. No polyethylene is used which can contribute to debris disease. Wear in ceramic bearings will be negligible. Third body inclusions must be avoided. The femoral spigot must not impinge on the acetabular margin. The ceramic material has to be supported to prevent fracture

BACKGROUND CONTEXT. Ceramic bearings are widely used in total hip arthroplasty (THR) along with metal and polyethylene bearings. There were several studies in past few years evaluating the advantage of one over the other. The young population with high activity levels has an increased risk of wear debris production at bearing surface and subsequent implant failure. Recently, interest and use of a ceramics with high wear resistance has been growing. Early reports on ceramic on ceramic THR have demonstrated excellent clinical and radiological results. PURPOSE. To evaluate clinical, functional and radiological outcomes of cement-less ceramic on ceramic primary total Hip Replacement (THR) in young patients (<50 years age) with diagnosis of avascular necrosis femoral head. STUDY DESIGN. Single - centre, prospective comparative study of prospectively collected outcomes, with a minimum of 12 month follow-up. PATIENT SAMPLE. 30 patients who underwent cement-less ceramic on ceramic primary THR in young patients (< 50 years age) for avascular necrosis of femoral head. OUTCOME MEASURES. For clinical evaluation, Harris hip scores was measured pre-operatively and post-operatively at predefined intervals. For radiological evaluation, Post- operative radiographs were checked for alignment of femoral stem, loosening of stem, presence of heterotopic ossification, loosening of acetabular component at predefined regular intervals. METHOD. This study included 30 patients, who underwent cement-less ceramic on ceramic primary THR in young patients (< 50 years age) for avascular necrosis of femoral head between July 2013 to April 2015 with a minimum of 12 month follow –up. RESULTS. The mean Harris hip score in our study increased from 32.73 pre-operatively to 87.8 post-operatively at the latest follow up with 90% hips having good to excellent results. This improvement was statistically significant (p<0.005). On evaluation of alignment of femoral stem 27 stems were central (90%) and 3 stems found to be in valgus (10%) and none to be in varus position. There was no significant correlation between stem alignment and clinical outcome based on Harris hip score. Not a single case of focal osteolysis, stem loosening or heterotopic ossification was seen in our study till latest follow-up. None of the major complication was noticed during evaluation of our cases except minor chronic hip pain in one patient which did not restricted his daily living activities. CONCLUSION. In our study, we found better results of ceramic on ceramic THR for younger patients(<50 years age) comparable to previous studies with no serious complication found in any patient. Based on our study, we recommend ceramic on ceramic THR for younger patients in the age group of less than 50 years of age. We need a study of large sample size with long term follow up to further confirm the findings of our study

Introduction: The treatment of stage 3 hallux rigidus is controversial. Cheilectomy, fusion and total joint replacement have all been advocated. No consensus is agreed on the best optimal management. We present our results of a ceramic on ceramic MOJE metatarsophalangeal (MTP) joint replacement. Aim: To find out the medium to long term outcome following MOJE MTP joint replacement. Material and Methods: A sample of 95 patients was identified, between January 1999 to July 2006 from our data base who underwent MOJE metatarsophalangeal joint replacement. We divided these patients into three groups. First group had screw fit ceramic MOJE joint replacement; second group Mark 1 ceramic on ceramic press fit MOJE joint replacement and third group Mark 2. Indications of the surgery were osteoarthritis (primary or secondary), osteochondral defects, inflammatory arthropahty, previous infections and previously failed surgery. The outcome was analysed clinically, radiologically and functionally (using AOFAS and QALY scoring system). Results: This study shows that the early results are promising but the medium and long term results show early radiological loosing. The significance of this is not known but based on these results we would advice caution on the use of these implants and further long term studies are required

Aims Osteolysis from polythene debris contributes to loosening of total hip components. Will ceramic/ceramic bearings in conjunction with Hydroxyapatite Ceramic Coated Hips (HAC) survive any better?. Material. Hydroxyapatite Ceramic Coated Hips were first used in Sunderland, U.K. in May 1988. More than 2400 HAC hips have been inserted. There are 521 hips in 441 patients with ceramic/ceramic bearings. I am reporting this consecutive series. These hips are generally inserted into patients with a 20+ year life expectancy. This ranges from 18 to 74. Mean age is 52.4 years. These young patients are mostly active and many are working. Amongst the indications were osteoarthritis 297, hip dysplasia 76, and ankylosing spondylitis 18. Thirty eight had had previous childhood hip disorders, and 19 had rheumatoid arthritis. The series also includes 43 with AVN and 7 revisions from cemented hip replacement. All the patients are assessed using the Harris Hip Score before and after surgery. They are assessed annually. Post operative scores show 22 patients with Harris Hip Scores of less than 80, but only 9 patients have problems attributable to HAC hip surgery. These include 2 patients with infection, 3 fractured ceramic acetabular liners, two broken heads and 2 patients with loose cups, one from aseptic loosening. Apart from this one case, aseptic loosening has not been a problem. Discussion. The results have been rewarding. There are 2400+ HAC hips in the whole series. This sub group of 521 ceramic/ceramic HAC hips is small with a maximum follow up of 14 years. However, there have been few failures which could be attributed to the HA coated device. The broken ceramic components are a concern. It is probable that third body inclusions between the modular components led to stress concentrations. It is also possible that acetabular impingement was a problem and the hips may have been subluxing a few microns with every step and not just gliding with every step. This might overload the alumina implants leading to their failure. All the earlier prostheses are alumina/alumina but 55 hips inserted since august, 2005 have an alumina/zirconia compound head (Biolox Delta®). There have been no cases of periprosthetic osteolysis. Conclusions. Hydroxy Apatite bony bonding secures the implants. No cement or polyethylene is used which can contribute to osteolysis. Wear in ceramic bearings will be negligible. Third body inclusions must be avoided to prevent wear or fracture. The femoral spigot must not impinge on the acetabular margin causing subluxation which may lead to fracture. The ceramic material has to be supported to prevent fracture. The outcome of the patients in this sub-group has been rewarding. Alumina/alumina hip arthroplasty should be considered where life expectancy is substantial

Background: Squeaking in hip arthroplasty is a phenomenon that was described decades ago, but has only been brought back to attention recently. It occurs predominantly in ceramic on ceramic bearings, and has a reported incidence from less than 1% to 21%. The cause and the implication of squeaking are still unknown and many factors have been suggested to contribute. This study has looked into the patient factors to investigate if any clinical features are associated with an increased risk of squeaking. Methods: All primary total hip arthroplasties with ceramic on ceramic bearing that were performed at our unit were reviewed and all squeaking hips presented are included in the study. Patient demographics and clinical outcome data were analysed and compared with matched controls from the silent hips. Results: Between 1997 and 2008, 3375 primary hip arthroplasties in 3182 patients with ceramic on ceramic bearing were performed in our unit. Seventy one hips (2.1%) presented with squeaking on direct questioning and self reporting. Those patients were found to be taller, heavier and younger. They also have a significantly higher post-operative range of hip motion and higher Harris hip score when compared to matched controls. There was no difference in the satisfaction score. Only 4 patients (5.6%) presented with pain as well as squeaking, and 2 (2.8%) resulted in revision surgery for problematic squeaking. Conclusions: We present the largest series of squeaking primary hip arthroplasties with ceramic on ceramic bearing to date. A number of patient factors were found to be associated with squeaking. The taller, heavier and younger patients with more flexible and functional hips were at a higher risk, presumably because these patients put greater mechanical demands on their hips. Majority of the patients with squeaking are pain free and there is only a small risk of requiring revision surgery

Introduction: With ceramic on ceramic bearing surfaces in total hip arthroplasty audible noise is a frequently documented problem. With increasing head size, there is less chance of component-on-component impingement and therefore a decreased risk of chipping, breaking and maybe noise occurrence. Material and Methods: Prospective multicentre follow-up study of n=149 cases (91 males and 58 females). All patients were treated with either 32 or 36mm ceramic on ceramic articulation (Bionit. ®. ) in combination with the non-cemented modular pressfit cup seleXys. ®. (Mathys Ltd Bettlach, Switzerland). There were n=4 patients with bilateral surgery. 56 patients received a 32mm head whereas 93 patients were treated with a 36mm head. In the group with 32 mm head diameter 79% were women, whereas in the 36 mm group only 16% were women. Patients were operated between December 2005 and January 2007. The mean age at surgery was 67.2 years (range, 46.3 – 86.4 years). Mean body mass index was 28.0 kg/m2 (range, 17.1 – 45.4 kg/m2). Patients were followed clinically and radiographically at three and six months, then after one and two years. Results: 5 patients died and 2 patients were lost to follow-up. Only one patient reported squeaking noise immediately after the operation. At the one year follow-up the patient reported a feeling of subluxation and the noise turned into a clicking. The patient had to be revised after 14 months with a polyethylene inlay. No other revisions had taken place. Patients with femoral heads of 32 mm and 36 mm diameter had excellent clinical results after 2 years follow-up for flexion angle, range of motion and Harris Hip Score. The Harris Hip Score increased from a pre-operative mean of 48.7 points to 93.5 points. Hip flex-ion increased from 91° to 113°. The Visual Analogue Scale for pain decreased from 6.7 to 0.9 and VAS for satisfaction increased from 3.2 to 9.3. Conclusion: Compared to other studies the occurrence of noise and resulting revision procedures is very low. We assume that the insertion of bigger heads may reduce this problem and simultaneously allow the patient a better range of motion. The non-cemented modular cup combined with a ceramic inlay and a ceramic femoral head is a safe implant with excellent clinical results after two years

Young patients have been reported to have a higher risk of revision following total hip arthroplasty than older cohorts. This was attributed to the higher activity level which led to increased wear, osteolysis, and component fracture. We prospectively assessed the clinical results, wear and osteolysis, the incidence of squeaking, and the survivorship of ceramic on ceramic THA in patients younger than 50 years (mean age of 42 [18–50] years). The series included 425 THAs in 370 patients with 368 hips followed for a minimum of 2 years (mean 7.1 years, range 2–14 years). All patients received uncemented acetabular components with flush-mounted acetabular liners using an 18 degree taper. No osteolysis was observed in any uncemented construct. There was osteolysis around one loose cemented femoral component. The survivorship for reoperation for implant revision was 96.7%. There were only two acetabular liner fractures (0.47%) and one femoral head fracture (0.24%). Two of the three fractures involved a fall from a significant height. There were no hip dislocations. Five patients (1.17%) noted rare or occasional squeaking. None had reproducible squeaking. In summary, the current study shows that ceramic-on-ceramic THAs in the young patient population are extremely reliable with a very low revision rate and an absence of wear-induced osteolysis. In addition, it shows that both bearing fracture in this young patient population typically occurs with polytrauma and squeaking issues that have been raised relative to ceramic bearings occur very rarely with the flush-mounted ceramic liner design used in this study

In vivo and in vitro studies of ceramic on ceramic (COC) bearings have demonstrated that swing phase microseparation followed by the impact of the femoral head on the superior acetabular insert rim leads to accelerated wear. However, resultant wear remained low. The wear of ceramic on polyethylene (COP) and metal on metal (MOM) couples under swing phase microseparation is unknown, this study aimed to compare the wear of these total hip replacements under standard and microseparation conditions. A physiological hip simulator was used, loads and motions were applied to approximate in vivo conditions. Microseparation was achieved by displacing the femoral head inferiorly during swing phase, the head contacted the inferior cup rim and was laterally displaced. On heel strike the head contacted the superior cup rim prior to relocation. Components (as shown in table 1) were tested for 5 million cycles, at a frequency of 1 hertz in 25% (v/v) new born calf serum. Under standard conditions, wear of COC and MOM bearings was significantly lower than wear of COP couples. Under microseparation conditions the COC and MOM wear increased by 4 and 25 times respectively. Microseparation conditions reduced wear of COP couples by a factor of 4. Creep deformation and damage to the UHMWPE cup rim was observed, however, wear remained low. It is postulated that this reduction in polyethylene wear is due to the separation of the components in swing phase improving the entrapment of lubricant, hence wear is reduced via a squeeze film lubrication mechanism

While crosslinked polyethylene has reduced the rate of wear and osteolysis in THA, osteolysis still occurs and taper-corrosion induced wear has become recognised as an increasing problem especially when larger diameter metal bearings are used. Long-term follow up studies of newer polyethylene bearings continue to lag those of ceramic-on-ceramic bearings by several years.

Ceramic-on-ceramic (CoC) bearing surfaces have consistently demonstrated reliable clinical results with when coupled with appropriated designed femoral stems and acetabular shells and have been shown to exhibit virtually no risk of adverse biologic reaction. Further, CoC bearings have not been associated with corrosion-induced adverse tissue reactions that occur with metal taper junctions.

Revisions for squeaking have been associated with specific designs and materials, including the use of a titanium elevated metal rim on the acetabular side, and more flexible femoral components made of a beta-titanium alloy (TMZF) which had thin necks and relatively small tapers.

Multiple clinical studies document excellent long-term survival of CoC bearing couples in young patients with revision for any reason as the primary endpoint. Our own experience with 341 hips in patients under 50 with 2–15 years and average 9.1-year follow up demonstrates a 95% overall survivorship (revision for any reason) at 13 years.

CoC bearings continue to show excellent durability in young, high demand patients with an absence of osteolysis in any case. CoC bearings continue to represent an excellent alternative to bearing couples containing polyethylene.

Ceramics are used in hip prostheses in approximately 40% of the implants (ce/ce and ce/pe). The increase of the diameters (32 and 36 mm) in order to improve the stability and the Range of Motion of the prostheses is now the topic. Research and development has allowed creating new alumina inserts with smaller out diameter (39 mm for the 32 mm bearing and of 44 mm for the 36 mm ones). The new alumina matrix composite has allowed the realization of ceramic revision ball-heads. This system, made of 28 or 32 mm ball-heads with a titanium slivers (12714 internal cone), will allow applications of the ceramic ball-head on an in situ damaged taper. Beyond S, M and L lengths, will be available also an XL version. A femoral knee component, still in phase of study, has shown advanced resistances of 5, 8 and 15 times the body-weight in different load configurations. Have been carry out some tests in order to estimate the adhesion between the ceramic and the cement of different thickness and have been caught up values of 6,17 MPa (2 mm) and 14,90 MPa (0,7mm)

INTRODUCTION. Analysis of retrieved ceramic components have shown areas of localized ‘stripe wear’, which have been attributed to joint laxity and/or impingement resulting in subluxation of the head, causing wear on the edge of the cup. Studies have been conducted into the effects of mild subluxation, however few in vitro tests have looked at severe subluxation. The aim of this study was to develop a more clinically relevant subluxation protocol. MATERIALS & METHODS. Seven (Subluxation n=4; standard test n=3) of 36mm Biolox Forte (R3, Smith & Nephew) ceramic devices were tested for 0.5m cycles (mc). Two of the subluxed joints were further tested to 1 Mc. The devices were subjected to subluxation under standard testing conditions. The flex/ext was 30° and 15° respectively, with internal/external rotation of ±10°. The force was Paul type stance phase loading with a maximum load of 3 kN, and a standard ISO swing phase load of 0.3 kN at 1 Hz. The test was conducted on a ProSim hip joint wear simulator (SimSol, UK). The simulator is equipped with a novel mechanism to achieve translation of the head, to achieve subluxation. During the ISO swing phase load of 0.3kN, a controlled lateral force required for the translation of the head is applied by a cam mechanism, head retraction then occurs during heel strike. The lubricant used was new born calf serum diluted with de-ionised water to achieve average protein concentration of 20 g/l, with 0.2 wt % concentration NaN3, and changed every 250k cycles. Measurements have been taken at 0.5 & 1 mc stages. RESULTS. Linear wear measurements conducted on the subluxed joints resulted in stripe wear similar to that reported in vivo. Average length, width and depth dimensions were 25.34±1.96 mm, 8±1.60 mm and 16.95±3.87 μm (± 95% CL) respectively. Linear wear at 0.5 Mc for standard joints, were undistinguishable from the original profile. Gravimetrically, weight loss was undetectable for joints tested under standard conditions. The volume loss of the joints under subluxation was 1.9± 0.7 mm3 at 0.5 mc. Two joints tested to 1mc generated an average volume loss of 3.1±2.3 mm3. The stripe wear length, width and depth at 1 Mc were 25.30±3.33mm, 8±3.92mm and 35±17.07 μm respectiveley. DISCUSSION. The current study presents test results of a hip joint simulator with a novel subluxation mechanism to simulate severe and clinically relevant hip joint. Past techniques have had to reduce the swing phase load to achieve stripe wear patches of varying size and depth. The subluxed joints produced significantly higher volumetric wear than the standard joints. Dimensional measurements in terms of length, width and depth of wear patches of subluxed joints generated similar results to that which have been observed following retrieval analysis. Tests that can simulate different types of activity in hip joint simulators will help to improve the design and understanding of implant behaviour in vivo

Audible squeaking following ceramic-on-ceramic total hip arthroplasty (THA) is a rare but troublesome problem. We retrospectively reviewed records of 1002 patients where a ceramic-on-ceramic THA had been done during the study period. Fifteen patients complained of squeaking, at any time following their arthroplasty. Fourteen of these 15 patients were evaluated clinically and radiologically. The demographics of these patients were compared to that of all the other patients who did not have squeaking following ceramic-on-ceramic THA. The radiographic data was compared to a control group matched for age, sex, body mass index (BMI), primary diagnosis, type of implant, date of surgery and length of follow-up.

There were 12 males and 2 females of a mean age of 44.5 years (range, 25–65 years). These 14 patients were found to have significantly higher BMI of 25.98 kg/m2 (range, 21.6–32.3 kg/m2) as compared to the other patients who had ceramic-on-ceramic THA (mean, 23.61 kg/m2; range, 15.8 –30.3 kg/m2) (p=0.005). The lateral opening angle was found to be significantly lower (mean, 34°; range 29°–40°) in these patients than the matched control group (mean, 38°; range 30°–41°) (p=0.016). Mean acetabular anteversion was 22° (range 9°–37°), which was not significantly different to that of the matched controls (mean 23°; range 2°–33°) (p=.957). Limb length shortening of more than 5mm was observed in 12 of the 14 (85.7%) patients as compared to only 4 of 14 (28.6%) patients in the matched control group. Two patients had intermittent squeaking while the other 12 had continuous squeaking. Flexion and sitting cross legged were identified as the movements which most commonly (11 of 12) resulted in squeaking. Mean Harris hip score (HHS) improved from 44 (range, 19–66) to 94 (range, 88–100) and most patients (13 of 14) were satisfied with the outcome of the surgery.

Thus the incidence of squeaking was found to be low (1.5%, 15 of 1002) in our series. We identified high BMI, decreased lateral opening angle and limb length shortening as factors associated with occurrence of squeaking. Proper patient selection, implant placement, and avoidance of limb length discrepancy are likely to further reduce the incidence of this complication of ceramic-on-ceramic THA.