A number of studies have reported satisfactory results from the isolated revision of an acetabular component. However, many of these studies reported only the short- to intermediate-term results of heterogeneous bearing surfaces in a mixed age group.

We present our experience of using a ceramic-on-ceramic (CoC) bearing for isolated revision of an uncemented acetabular component in 166 patients (187 hips) who were under the age of 50 years at the time of revision. There were 78 men and 88 women with a mean age of 47.4 years (28 to 49). The most common reason for revision was polyethylene wear and acetabular osteolysis in 123 hips (66%), followed by aseptic loosening in 49 hips (26%).

We report the clinical and radiological outcome, complication rate, and survivorship of this group. The mean duration of follow-up was 15.6 years (11 to 19).

The mean pre-operative Harris hip score was 33 points (1 to 58), and improved to a mean of 88 points (51 to 100) at follow-up. The mean pre-operative total Western Ontario and McMaster Universities Osteoarthritis Index score was 63.2 (43 to 91) and improved to 19.8 points (9 to 61) post-operatively. Overall, 153 of 166 patients (92%) were satisfied with their outcome. Kaplan–Meier survivorship analysis, with revision or radiological evidence of implant failure (13 patients, 8%) as end-points, was 92% at 15 years (95% confidence interval 0.89 to 0.97).

Isolated revision of a cementless acetabular component using a CoC bearing gives good results in patients under 50 years of age.

Cite this article: Bone Joint J 2015;97-B:1197–1203.

Dislocation is a common reason for revision following total hip replacement. This study investigated the relationship between the bearing surface and the risk of revision due to dislocation. It was based on 110 239 primary total hip replacements with a diagnosis of osteoarthritis collected by the Australian Orthopaedic Association National Joint Replacement Registry between September 1999 and December 2007. A total of 862 (0.78%) were revised because of dislocation. Ceramic-on-ceramic bearing surfaces had a lower risk of requiring revision due to dislocation than did metal-on-polyethylene and ceramic-on-polyethylene surfaces, with a follow-up of up to seven years. However, ceramic-on-ceramic implants were more likely to have larger prosthetic heads and to have been implanted in younger patients. The size of the head of the femoral component and age are known to be independent predictors of dislocation. Therefore, the outcomes were stratified by the size of the head and age. There is a significantly higher rate of revision for dislocation in ceramic-on-ceramic bearing surfaces than in metal-on-polyethylene implants when smaller sizes (≤ 28 mm) of the head were used in younger patients (< 65 years) (hazard ratio = 1.53, p = 0.041) and also with larger (> 28 mm) and in older patients (≥ 65 years) (hazard ratio = 1.73, p = 0.016)

We have developed a CT-based navigation system using infrared light-emitting diode markers and an optical camera. We used this system to perform cementless total hip replacement using a ceramic-on-ceramic bearing couple in 53 patients (60 hips) between 1998 and 2001. We reviewed 52 patients (59 hips) at a mean of six years (5 to 8) postoperatively. The mid-term results of total hip replacement using navigation were compared with those of 91 patients (111 hips) who underwent this procedure using the same implants, during the same period, without navigation. There were no significant differences in age, gender, diagnosis, height, weight, body mass index, or pre-operative clinical score between the two groups. The operation time was significantly longer where navigation was used, but there was no significant difference in blood loss or navigation-related complications. With navigation, the acetabular components were placed within the safe zone defined by Lewinnek, while without, 31 of the 111 components were placed outside this zone. There was no significant difference in the Merle d’Aubigne and Postel hip score at the final follow-up. However, hips treated without navigation had a higher rate of dislocation. Revision was performed in two cases undertaken without navigation, one for aseptic acetabular loosening and one for fracture of a ceramic liner, both of which showed evidence of neck impingement on the liner. A further five cases undertaken without navigation showed erosion of the posterior aspect of the neck of the femoral component on the lateral radiographs. These seven impingement-related mechanical problems correlated with malorientation of the acetabular component. There were no such mechanical problems in the navigated group. We conclude that CT-based navigation increased the precision of orientation of the acetabular component and control of limb length in total hip replacement, without navigation-related complications. It also reduced the rate of dislocation and mechanical problems related to impingement

Bearing surfaces in Total Hip Arthroplasty (THA) may affect implant longevity and hence patient outcomes. This randomised clinical trial (RCT) determined how ceramic-on-ceramic bearing (CERAMIC) THA affected joint-specific pain, function and stiffness, and prosthesis fixation/longevity over 10 postoperative years compared with ceramic-on-highly-crosslinked-polyethylene bearing (POLYETHYLENE) THA. This is a follow-up to previously reported five year outcomes. Subjects aged less than 61 years were randomised to CERAMIC [n=48] or POLYETHYLENE [n=44] THA. Subjects were assessed using the Western Ontario McMaster Osteoarthritis Index (WOMAC) and the RAND 12-Item Health Survey (RAND-12) preoperatively, and at one, five and 10 years postoperatively. Plain radiographs were evaluated at 10 years for fixation and medical records were reviewed for revisions. Of 92 subjects, six (7%) died within 10 years; 68 (79%) survivors provided radiographic and/or clinical follow-up at 10 years postoperatively. Improvements seen at five years in both the WOMAC and RAND-12 were retained at 10 years with no group differences (p>0.48). There were no failures/loss of fixation related to bearing surfaces/wear in either group. Over 10 years, three subjects in the POLYETHYLENE group had revisions that were related to recurrent dislocation; two revisions were performed within two years of surgery and one further subject underwent revision at 7 years postoperatively. This is one of the first RCTs to examine 10 year outcomes between ceramic-on-ceramic and ceramic-on-highly-crosslinked-polyethylene bearing THA. Both bearing surfaces performed well out to 10 years in subjects who were less than 61 years at time of surgery

The ideal bearing surface for total hip arthroplasty is still an area of debate.Increasing numbers of total hip replacements are being done in the younger patient population.Ceramic-on-ceramic bearings have gained popularity due to their low wear rate.However, ceramic fractures with subsequent catastrophic failures have been reported. This study reports on early results of ceramic-on-ceramic total hip replacements. This is a study analyzing a prospectively collected data for seventy-five ceramic-on-ceramic total hip replacements with minimum follow up of eighteen months. Average age at time of surgery was forty-seven years. This study focused on the complications of this ceramic population. Complications included: One posterior dislocation, two intra-operative calcar fractures that needed wiring, one intra-operative fracture of the acetabular liner, two cases of impingement (one which resulted in a revision), and one periprosthetic fracture. The two patients that required further surgery were the periprosthetic fracture after a fall and one for component impingement. No revisions were performed for loosening or catastrophic failures. No wear, loosening, or osteolysis was seen on radiographs. The SF-12, WOMAC, and Harris Hip scores were not significantly different from other reported hip series. Ceramic-on-ceramic bearing surfaces in total hip arthroplasty are a safe option with outcome equivalent to standard THR in the short term. Ceramic Hips may provide a more durable prosthesis, especially in young and active patients. Intra-operative technical guidelines that may enhance the quality of the results will be presented and fully disclosed

Introduction and Objective

Ceramic on Ceramic bearings in Total Hip Arthroplasty (THA) afford a low friction coefficient, low wear rates and extreme hardness. Significant complications include hip squeak, ceramic fracture and poor polyethylene performance in revision procedures due to imbedding of abrasive microscopic ceramic fragments. We report on the results of this bearing at a minimum of 10 years.

Aims

Ceramic-on-ceramic (CoC) bearings in total hip arthroplasty (THA) are commonly used, but concerns exist regarding ceramic fracture. This study aims to report the risk of revision for fracture of modern CoC bearings and identify factors that might influence this risk, using data from the National Joint Registry (NJR) for England, Wales, Northern Ireland and the Isle of Man.

Ceramic-on-ceramic (CoC) articulations in total hip arthroplasty (THA) have low wear, but the unique risk of fracture. After revision for CoC fracture, ceramic third bodies can lead to runaway wear of cobalt chrome (CoCr) causing extremely elevated blood cobalt. We present five cases of ceramic liner fractures revised to a CoCr head associated with the rapid development of severe cobalt toxicity.

We identified 5 cases of fractured CoC THA treated with revision to CoCr on highly cross-linked polyethylene (HXLPE) – three to conventional bearings and two to modular dual mobility bearings (CoCr acetabular liner, CoCr femoral head, and HXLPE). Mean follow up was 2.5 years after CoCr/HXLPE re-revision.

Symptoms of cobalt toxicity occurred at average 9.5 months after revision for ceramic fracture (range 6–12). All patients developed vision and hearing loss, balance difficulties, and peripheral neuropathy. Several had cardiomyopathy, endocrinopathy, and local skin discoloration. Two reported hip pain. Re-revision for cobalt toxicity occurred at an average of 22 months (range 10–36) after revision for ceramic fracture. Average serum cobalt level at re-revision was 991 μg/L (range 734–1302, normal <1 μg/L). All CoCr heads exhibited massive wear with asphericity; deep tissues exhibited prominent metallosis. Treatment consisted of debridement and revision to a ceramic head with HXLPE. Serum cobalt improved to an average of 25 μg/L at final follow up. All patients reported partial improvement in vision and hearing; peripheral neuropathy and balance did not recover.

Systemic cobalt toxicity is a rare but devastating complication of ceramic fracture in THA treated with cobalt-alloy bearings. Cobalt alloy bearings should be avoided in this setting. The diagnosis of systemic cobalt toxicity requires a high index of suspicion and was typically delayed following systemic symptoms. Debridement and revision to a ceramic-on-HXLPE leads to improvement but not resolution of cobalt toxicity complications.

Ceramic on ceramic (CoC) bearings in total hip arthroplasty (THA) are commonly used but concerns exist regarding ceramic fracture. This study aims to report the risk of revision for fracture of modern CoC bearings and identify factors that might influence this risk, using data from the National Joint Registry.

We analysed data on 111,681 primary CoC THA's and 182 linked revisions for bearing fracture recorded in the National Joint Registry of England, Wales, Northern Ireland and the Isle of Man (NJR). We used implant codes to identify ceramic bearing composition and generated Kaplan-Meier estimates for implant survivorship. Logistic regression analyses were performed for implant size and patient specific variables to determine any associated risks for revision.

99.8% of bearings were CeramTec Biolox® products. Revisions for fracture were linked to 7 of 79,442 (0.009%) Biolox® Delta heads, 38 of 31,982 (0.119%) Biolox® Forte heads, 101 of 80,170 (0.126%) Biolox® Delta liners and 35 of 31,258 (0.112%) Biolox® Forte liners. Regression analysis of implant size revealed smaller heads had significantly higher odds of fracture (χ2=68.0, p<0.0001). The highest fracture risk were observed in the 28mm Biolox® Forte subgroup (0.382%). There were no fractures in the 40mm head group for either ceramic type. Liner thickness was not predictive of fracture (p=0.67). BMI was independently associated with revision for both head fractures (OR 1.09 per unit increase, p=0.031) and liner fractures (OR 1.06 per unit increase, p=0.006).

We report the largest registry study of CoC bearing fractures to date. Modern CoC bearing fractures are rare events. Fourth generation ceramic heads are around 10 times less likely to fracture than third generation heads, but liner fracture risk remains similar between these generations.

To analyze the long term results of a third generation ceramic on ceramic bearing in cementless total hip arthroplasty (THA), we reviewed the clinical and radiological results of 100 consecutive THAs performed in 86 patients (68 females, 80 hips; 18 males, 20 hips) between 1996 and 1998. The average age at operation was 55 years with a range of 26 to 73 years. The diagnoses were osteoarthritis in 83 hips, osteonecrosis in 10 hips and rheumatoid arthritis in 7 hips. The articulation was composed of a hemispherical titanium porous bead-coated cup (AnCA), a Biolox Forte alumina ceramic cup liner and a ball with a diameter of 28-mm. The modular ceramic liner was fixed directly to the metal cup without polyethylene sandwich or metal rim. A press-fit technique of 1 mm under-reaming without screws was used for cup fixation. The ceramic head was fixed to a 12/14 taper cone of a modular neck which allowed changes in neck-shaft angle, anteversion, and offset. All operations were performed via a posterolateral approach under general anesthesia. To measure the cup orientation, an ellipse was fitted to the acetabular component rim on the early postoperative AP radiographs using computer software. The average cup inclination and anteversion in the radiographic definition were 41 (range 28 to 63) and 17 (range 3 to 34) degrees, respectively. 22 cups were outside the Lewinnek safe zone. All patients were radiographically evaluated in term of implant stability at two years using Engh’s criteria. All of the acetabular components radiologically were judged to be bone-ingrown stable at two years except one cup. 98 stems were judged to be bone-ingrown stable and the remaining two stems were judged to be fibrous stable at two years. After two years, all patients except for two were followed up clinically and radiologically for at least 10 years or until revision or death. One unstable cup was revised at 2.5 years. This case had a previous Chiari’s pelvic osteotomy and insufficient press-fit of the cup was assumed to have led to loosening. One of the two fibrous stable stems was revised at six years due to aseptic loosening. One rheumatoid arthritis hip with stable bone ingrown fixation developed late infection at six years and was revised. One stable cup showed chipping of the acetabular liner at 8 years and required revision. The orientation of this cup was 55 degrees of inclination and 17 degrees of anteversion and the high inclination was thought to be related to the ceramic liner chipping. The remaining hips showed no osteolysis or loosening at the final follow-up. There were no squeaking hips. The 10-year survivorships with the endpoint of mechanical loosening or revision were 96.7% and 95.6%, respectively. We conclude that the third generation ceramic on ceramic hip bearing without polyethylene sandwich provided long term stability and eliminated periprosthetic osteolysis.

The problem associated with ceramic on ceramic total hip replacement (THR) is audible noise. Squeaking is the most frequently documented sound. The incidence of squeaking has been reported to wide range from 0.7 to 20.9%. Nevertheless there is no study to investigate on incidence of noise in computer assisted THR with ceramic on ceramic bearing. The purpose of this study was to determine the incidence and risks factors associated with noise. We retrospectively reviewed 200 patients (202 hips) whom performed computer assisted THR (Orthopilot, B. Braun, Tuttlingen, Germany) with ceramic on ceramic bearing between March 2009 and August 2012. All procedures underwent uncemented THR with posterior approach by single surgeon. All hips implanted with PLASMACUP and EXIA femoral stem (B. Braun, Tuttlingen, Germany). All cases used BIOLOX DELTA (Ceramtec, AG, Plochingen, Germany) ceramic liner and head. The incidence and type of noise were interviewed by telephone using set of questionnaire. Patient's age, weight, height, body mass index, acetabular cup size, femoral offset size determined from medical record for comparing between silent hips and noisy hips. The acetabular inclination angle, acetabular anteversion angle, femoral offset, hip offset were reviewed to compare difference between silent hips and noisy hips. The audible noise was reported for 13 hips (6.44%). 5 patients (5 hips) reported click (2.47%) and 8 patients (8 hips) squeaked (3.97%). The mean time to first occurrence of click was 13.4 months and squeak was 7.4 months after surgery. Most common frequency of click was less than weekly (60%) and squeak was 1–4 times per week (50%). Most common activity associated with noise was bending; 40% in click and 75% in squeaking. No patients complained for pain or social problem. Moreover, no patient underwent any intervention for the noise. The noise had not self-resolved in any of the patients at last follow up. Age, weight, height and BMI showed no statistically significant difference between silent hips and click hips. In addition, there was also same result between silent hips and squeaking hips. Acetabular cup insert size and femoral offset stem size the results showed that there was no statistically significant difference between silent hips and click hips, also with squeaking hips. Acetabular inclination, angle acetabular anteversion angle, femoral offset, hip offset the results shown that only acetabular anteversion angle differed significantly between silent hips (19.94±7.78 degree) and squeaking hips (13.46±5.54 degree).

The results can conclude that incidence of noise after ceramic on ceramic THR with navigation was 6.44 %. Squeaking incidence was 3.97% and click incidence was 2.47%. The only associated squeaking risk factor was cup anteversion angle. In this study, squeaking hip had cup anteversion angle significant less than silent hip.

Introduction

The prevalence of adverse reactions to metal debris around metal-on-metal (MOM) hip replacements has been reported to range from 7 to 69%. Little has been published on MRI scans with conventional total hip bearing surfaces. This study aimed to establish the prevalence of soft tissue lesions associated with metal-on-polyethylene (MOP) and ceramic-on-ceramic (COC) bearings, compared to MOM prostheses.

Total Hip Arthroplasty (THA) has been more frequently performed for relatively young patients with osteonecrosis of the femoral head in Korea. Moreover, squatting and sitting with crossed legs are more common in Asian cultures than in Western cultures. Wear debris generated by conventional metal-on-PE articulations has been giving rise to extensive osteolysis. Due to these characteristics, higher incidence of pelvic osteolysis was observed after THA in Korea. As a result, interest in alternative bearings such as ceramic-on-ceramic bearing has been increased. Furthermore, the patients who require revision THA are still young in Korea. With this point of view, an application of ceramic-on-ceramic bearing throughout revision THA seems to be reasonable. The clinical and radiographical outcomes after revision THA with use of third generation ceramic-on-ceramic bearing in Korean patients were evaluated. Materials and Methods: We have analyzed 42 hips (37 patients; 17 men and 20 women), in whom revision THAs were performed using cementless cups with ceramic-on-ceramic bearing (Biolox Forte; CeramTec, Plochingen, Germany). They underwent THA at a single institution between February 2000 and December 2004, and were consecutively enrolled in this study. Their mean age was 48.8 years (32 – 59 years), and their mean weight was 61.5 ± 5.8 kg (50 – 72 kg) and BMI was 23.8. The mean interval from primary to revision THA was 9.5 ± 3.2 years (3.3 – 16.1 years). The preoperative diagnoses for primary THA were osteonecrosis of the femoral head in 31 hips, neglected femoral neck fracture in 3, rheumatoid arthritis in 2, degenerative osteoarthritis in 2, pyogenic arthritis in 2, tuberculosis arthritis in 1, and fused hip in 1. Dissociation of PE liner was observed in 21 hips (50%). For acetabular cup revision, Trilogy ceramic acetabular cups (Zimmer, Warsaw, IN) were used in 22 hips, EP-FIT plus cups (Plus Orthopedics, Rotkreuz, Switzerland) in 14 hips, and Duraloc Option Ceramic cups (DePuy, Warsaw, IN) in 6 hips. Stems were revised in all hips. The follow-up protocol included radiographic and clinical evaluations, and the mean duration of follow-up monitoring after revision THA was 5.4 ± 1.7 years (3.2 – 8.0 years). At final follow-up examination, clinical outcomes including Harris Hip Score and complications were assessed. All changes in inclination were documented radiographically. The presence of radiolucent lines, vertical or horizontal migration of acetabular cup (> 2 mm), and osteolysis were also evaluated. Results: At final follow-up evaluation after revision, the average Harris Hip Score was 91.3. There were no revised hips during follow-up period. In 6 hips (14.3%), minor complications were observed: 3 heterotopic ossifications, 2 dislocations, 1 infection. No revision was necessary for the treatment of these complications. There were no hips with radiolucent lines, vertical or horizontal acetabular cup migration or osteolysis during the follow-up period. In 21 hips with bone graft, incorporation of bone graft was observed radiographically at final follow-up examination. Conclusions: Our data showed that clinical and radiographical outcomes after revision THA using third generation ceramic-on-ceramic bearing were favorable. Revision THA with the use of ceramic-on-ceramic bearing surfaces can be preferentially considered especially in young patients. Further studies with long-term follow-up data are warranted

Purpose of the study: The ceramic-on-ceramic bearing for total hip arthroplasty (THA) has been widely used in Europe for many years. There have however been few publications on its long-term outcome. The purpose of this study was to examine the outcome at nine years follow-up of 100 THA implanted without cement using a ceramic-on-ceramic bearing. Material and methods: The first 100 ceramic-on-ceramic THA implanted from November 1999 in our unit in patients aged less than 65 years were studied. The clinical assessment included the physical examination with search for complications and the Harris and Postel-Merle-d’Aubigné scores noted preoperatively and at last follow-up. The radiographic assessment was performed by two surgeons (double reading) to search for peri-prosthetic lucency, osteolysis, ossifications and implant migration. The state of the calcar was noted. The Delee-Charnley classification was used to classify the lucent lines for the acetabulum and the Gruen McNiece and Amstutz classification for the femur. Results: Among the 100 THA, 20 patients were lost to follow-up. The Harris score was 42.6 (29–55) preoperatively and 93.9 (67–100) at last follow-up. The PMA was 8 (5–11) preoperatively and 16.7 (9–18) at last follow-up. One hip was revised to change the acetabular implant at five years. There were six early dislocations [one episode (n=4), two episodes (n=2)], one late dislocation, and two episodes of subluxation without recurrence. There were no fractures of the femoral head. The radiographic analysis identified moderate bone absorption of the calcar without real osteolysis in nearly all of the patients. For a few patients, a lucent line seen early postoperatively had disappeared at last follow-up. No implant migration (cup, stem) was noted. Discussion: The clinical and radiographic outcomes are in agreement with the literature. The relatively high rate of dislocation can be explained by the diverse levels of experience of the surgical teams. The prostheses presenting dislocation did not have an unfavourable outcome, particularly radiographically. Conclusion: These clinical and radiographic results at nine years follow-up, and the current systematic use of computer assisted navigation for optimal implant positioning favour continuation of the implantation of the ceramic-on-ceramic bearing in patients aged less than 65 years

Summary Statement. The frictional torque of ceramic-on-ceramic bearings tended to increase with increasing the bearings size (32, 48, 56mm). However, the frictional torque was significantly lower than that measured on metal-on-metal bearings under well positioned and well lubricated conditions. Introduction. Larger head size in total hip replacement theoretically provides increased range of motion and enhanced stability. However, there are potential clinical concerns regarding increased frictional torques with large diameter metal-on-metal bearings causing loosening of the acetabular cups and corrosion at the taper. The aim of this study was to determine the frictional torques of large diameter BIOLOX® delta ceramic-on-ceramic bearings. Materials and Methods. The single-station pendulum friction simulator (SimSol, UK) was used to determine the frictional torque of three ceramic-on-ceramic bearing sizes: 32mm and 48mm (DeltaMotion®, DePuy Synthes Joint Reconstruction, Leeds, UK) and a 56mm prototype design. Four repeats were tested for each bearing size using 100% new-born calf serum, 25% new-born calf serum and water as lubricants. The input profiles were a simplified loading regime with a peak of 2kN and an angular motion of ±25° [1]. The frictional torque was determined under swing phase loads of 25N, 100N or 300N. The bearings were tested under standard conditions where the cup was positioned so the face was horizontal to the loading axis and at an inclination angle equivalent to 65° in vivo. Results. When lubricated with 100% serum, size 48mm bearings showed similar frictional toque to the 32mm bearings (1.5Nm and 1.7Nm respectively, p=0.28), however, the frictional torque of the 56mm prototype design bearings was significantly higher (2.2Nm, p=0.01). When using 25% serum, there was a trend of increased frictional torque (p=0.016) with increased head size; increasing from 1.2 Nm to 1.5 Nm to 1.9 Nm for the 32mm, 48mm, and 56mm bearings respectively. The frictional torque significantly decreased when water was used compared to using new-born calf serum as lubricant. There was no significant difference in the frictional torque between all bearings sizes with water as lubricant, however, there was a trend of increased frictional torque with increased swing phase load. Changing the swing phase load had no influence on the frictional torques obtained for all bearing sizes when using 100% or 25% new-born calf serum. Under a steep inclination angle, the frictional torque for all bearing sizes did not significantly change compared to the flat cup condition. Discussion and Conclusion. The frictional torque tended to increase with increased head size. The highest frictional torque measured in this study was 2.5Nm for the 56mm ceramic-on-ceramic bearing (25% serum, steep cup) compared to 5.3Nm maximum torque measured using the same method for well-positioned and well lubricated 54mm metal-on-metal bearings. The frictional torque for all ceramic-on-ceramic bearing sizes (32mm, 48mm, and 56mm) decreased as the concentration of protein decreased. This was consistent with previous work done on 28mm bearings and the understanding that for ceramic-on-ceramic bearings the adherence of proteins to the surface reduces the effectiveness of lubricant film thickness, thus resulting in higher frictional torques due to the force required to shear the proteins

Introduction. Dislocation is one of the major factors for revision surgery. Current literature states that the usage of larger bearing couples (> 36 mm) have the potential of reducing the risk of dislocation. Smaller ceramic-on-ceramic bearing couples (< 36 mm) have demonstrated very low wear rates. But does the wear behaviour change with increasing diameter? Therefore, the aim of this study was to compare wear rates of larger ceramic-on-ceramic bearing couples for total hip arthroplasty. Materials and Methods. Wear tests according to ISO 14242 with 36, 40 and 44 mm zirconia platelet toughened alumina (ZPTA) bearings were performed in a servo-hydraulic hip simulator. In total, the specimens were loaded up to 5 million cycles. Wear was measured gravimetrically every million cycles. For each diameter three different combinations regarding clearance and roundness were chosen. One combination represented in tolerance parts (70 μm clearance, < 5 μm roundness). The other two combinations represented parts at the lower end and at twice the upper end of the tolerance band regarding clearance and out of specification parts regarding the roundness. Results. In general, ball heads showed higher wear than liners. 44 mm bearings showed highest and 36 mm bearings showed lowest run-in wear rates (Table 1). Except for the 36 mm bearing negligible influence on wear rates caused by the different clearance and roundness was found. The highest linear wear rate was found for the 36 mm bearing having a clearance of 20 μm and a roundness of 15 μm. The smallest linear wear rate was also found for the 36 mm bearing. Here, in tolerance parts were tested. Discussion and Conclusion. Generally, the current study shows extremely low wear rates for ZPTA/ZPTA even for larger diameter bearings. Except for the 36 mm bearing different machining tolerances in the investigated range seem to have only minor effects on the wear rates of larger diameter bearings under ISO 14242 test conditions. The wear rates determined in the current study might be lower in reality due to metal transfer from the tapers and the cups to the ball heads and liners occurring while assembling and disassembling procedures throughout testing. Larger diameter bearings increase range of motion, stability and reduce the risk of impingement. Thus, larger diameter ZPTA bearings have the potential to minimize the dislocation risk while at the same time having maintained the extremely low wear rates of small diameter ceramic articulations

Introduction: Dislocation is the most common complication resulting in re-operation following total hip arthroplasty, accounting for 33.5% of revisions. This study investigates the relationship between bearing surface and the risk of revision due to dislocation. Materials and Methods: Analysis was based on 110,239 primary total hip arthroplasties with a primary diagnosis of osteoarthritis. Data were collected by the Austra-lian Orthopaedic National Joint Replacement Registry from September 1999 to December 2007. The bearing surfaces were: 20627 (18.7%) ceramic-on-ceramic, 14001 (12.7%) ceramic-on-polyethylene, 12208 (11.1%) metal-on-metal, and 62437 (56.6%) metal-on-polyethylene. In 966 (0.8%) hips the bearing surface was unknown. Results: There were 862 (0.8%) hips revised due to dislocation, with a rate of 0.3 revisions per 100 component years. Survival analysis with an end point of revision due to dislocation was performed. Revision for dislocation is potentially associated with variables other than bearing surface (including age and femoral component head size). Therefore analyses were stratified by femoral head size (≤28mm and > 28mm), and age (< 65 years and ≤65 years). There is a significantly higher rate of revision for dislocation in ceramic-on-ceramic bearing surfaces compared to metal-on-polyethylene bearing surfaces after adjustment for age, sex and head size in the head size < =28mm/Age < 65 group (hazard ratio = 1.53, 95% C.I. = 1.02 to 2.30, p=0.041) and the head size > 28mm/Age > =65 group (hazard ratio = 1.73, 95% C.I. = 1.10 to 2.74, p=0.016). Discussion: Ceramic-on-ceramic bearing surfaces have a higher risk of revision due to dislocation in the femoral head sizes and ages discussed above, compared with metal-on-polyethylene. Possible mechanisms for this observed difference may include patient selection, the limits to head and liner offset options when using ceramic bearing surfaces or higher rates of revision after dislocation due to ceramic head or liner damage. However our results are based on a seven year follow-up, and higher rates of late dislocation with polyethylene bearings may be observed in association with higher wear rates compared with ceramic liners

Ceramic bearings are currently the most widely used alternative to metal-on-polyethylene bearings in total hip arthroplasty (THA). A workgroup at International Consensus Meeting (ICM) analyzed the potential link between the type of bearing surface and the subsequent periprosthetic joint infection (PJI), and found a higher incidence of PJI when using a metal-on-metal (MoM) bearing surface. A potential reason is that the failure of a MoM bearing surface can result in adverse local tissue reactions (ALTR), which might provide a favorable environment for bacterial proliferation. In the last few years, several observational studies including national registries, showed that metal-on-polyethylene (MoP) bearing surfaces are associated with a higher rate of infection following total hip arthroplasty (THA) compared to ceramic bearings, in particular with the use of ceramic-on-ceramic bearing (CoC) surfaces. After adjusting for selection bias and various confounding factors, patients treated with ceramic bearings experienced reduced risk of infection and MoP bearing surface is an independent risk factor correlating with higher incidence of PJI. The meta-analysis by Lee et al. comparing MoM with CoC cementless THA confirmed that the MoM is associated with a significantly higher revision rate than CoC group for any reason as well as for PJI. Furthermore, initial in-vitro studies have shown lower bacterial biofilm formation on ceramic bearing surfaces. Summarizing the current literature, ceramic bearings are associated with a lower risk of infection following THA

Introduction. The aim is to study the outcome of a consecutive single surgeon's series using the ReCap Hip resurfacing arthroplasty (HRA) system. Methods. This is an ongoing prospective study. HRA was performed in active males under 65 years with good bone quality and in pre-menopausal females with adequate bone density proven by a DEXA scan. Radiographs were analysed for acetabular inclination, notching, neck thinning and change in implant position. Pre-op and follow-up Oxford hip and UCLA scores were recorded. Results. 72 HRA's were performed in 66 patients with a mean age of 54.7 years. The mean follow-up was 5.96±1.33 years. The mean theta angle was 38.21±4.270 and stem-shaft angle was 139.98±6.650. Femoral neck thinning was observed in two cases. There was a significant improvement in Oxford Hip score and UCLA score (p<0.001). All patients returned to their normal level of activity. We did not observe any significantly abnormal Cobalt or Chromium levels at follow-up. One hip developed avascular necrosis at three years, and was revised to a ceramic-on-ceramic bearing. The survivorship was 98.61% at 5years. Conclusion. The ReCap hip resurfacing system demonstrated good medium-term results in a cohort of active patients, whom we will continue to monitor in the longer term

INTRODUCTION. Patients less than 60 years old have been reported to have a higher risk of revision following total hip arthroplasty (THA) than older patient cohorts, possibly to due higher activity, a higher incidence of deformity and greater probability of prior surgery. Ceramic-on-ceramic bearing surfaces have been proposed for use in young and active individuals due to their low wear, low risk of adverse biologic reaction, and long-term survivorship. We assessed the clinical results and long-term survivorship of uncemented ceramic-on-ceramic THA in a young patient population. METHODS. For the six year period from May 1999 to March 2005, 278 hip replacements in 244 patients less than 60 yeas of age at the time of surgery were performed using alumina ceramic-ceramic bearings. All hips had uncemented titanium femoral and acetabular components. The ceramic liner was fixed to the shell with an 18-degree flush-mounted taper design. Patients were followed clinically and radiographically. Attempts were made to contact all patients who had not been seen in the prior 3 years. Of the 278 hips, 17 hips (16 patients) remain lost to follow-up, leaving 261 hips (228 patients; 155 hips in men, 106 hips in women) for assessment. Mean age of the patients was 46.2 years at the time of surgery (range 17.8 to 59.9 years). 17% of hips had at least one previous hip surgery. Mean time following surgery was 9.75 years (range 2 to 16.8 years). RESULTS. At mean 9.75 year follow-up, none of these 261 hips experienced early or late deep infection or dislocation. Four patients died of causes unrelated to their arthroplasty at a mean of 6.1 years, all with well functioning constructs. Nine hips (3%) were revised: 2 stems and 2 cups failed to osseointegrate; 1 modular neck component sustained a modular neck fracture; and ceramic fracture occurred in 1 femoral head and 3 liners. Three of the 4 patients with fracture sustained severe trauma from life-threatening injuries. CONCLUSION. Total hip arthroplasty in young patients demonstrates excellent survivorship when uncemented titanium implants are coupled with ceramic-ceramic bearings