Different types of highly cross-linked polyethylene (HXLPE) have been introduced widely in acetabular cups in hip prostheses to reduce the incidence of wear debris-induced osteolysis. Also, we reported that HXLPE cups with 28-mm alumina ceramic femoral head exhibited lower wear than conventional PE cups. Recently, the combination of HXLPE cup and larger diameter femoral head is used widely to prevent dislocation. In this study, we examined the wear of HXLPE with 32-mm alumina ceramic femoral head and compared it with the wear of HXLPE with 28-mm alumina ceramic femoral head. The in vivo wear of 60 HXLPE cups (Aeonian; Kyocera Corp., Kyoto, Japan, currently Japan Medical Materials Corp., Osaka, Japan) with 28-mm alumina ceramic femoral head with clinical use for 3.1–9.1 years (mean 7.4 years) and eight HXLPE cups with 32-mm alumina ceramic femoral head used for 2.3–3.2 years (mean 2.8 years) were examined by radiographic analysis. The early wear rate for the first year of HXLPE cups with 28-mm and 32-mm alumina ceramic femoral head were 0.24±0.10 mm/year and 0.29±0.12 mm/year respectively. There was no significant difference in both femoral head groups (p>0.05). The steady wear rate after 1 year were 0.001±0.03 mm/year and −0.03±0.10 mm/year respectively. There was no significant difference either in both femoral head groups (p>0.05). These findings from this radiographic analysis suggest that the early wear rate in the first 1 year probably represents the creep deformation in bedding-in stage; and the steady wear rate after 1 year probably represents mainly the wear than of the creep deformation. By the radiographic analysis, HXLPE cups in both femoral head groups exhibited low steady wear rate. In conclusion, we expect that the combination of HXLPE cup and 32-mm diameter alumina ceramic femoral head has favorable wear properties with possibility of prevention of dislocation in long-term clinical use

Introduction. Wear of the ultra high molecular weight polyethylene (UHMWPE) cup and the resulting loosening has been shown to limit the long-term results of the Charnley low-frictional torque arthroplasty (LFA). Factors affecting wear rates have been studied: level of patient activity, effective roughness of the stainless steel head, impingement and the possible variations in wear characteristics of UHMWPE. Since patients' activity level cannot be predicted or modified, alternative materials were examined. Methods and Results. The Charnley 22.225 mm diameter head of alumina ceramic in combination with chemically cross-linked polyethylene cup has now reached over 23 years of clinical and radiographic follow-up. Of the initial 17 patients (19 hips) in the study, 4 patients (4 hips) have died, 1 hip has been revised for deep infection and 3 patients (3 hips) are unable to attend follow-up due to medical problems unrelated to the hip. Nine patients (11 hips) are still attending follow-up at a mean of 22 years 5 months (21 year 3 months-23 years 6 months). The mean age at surgery in this group was 47 years (26-58) and the mean weight 81kgs (54-102). The mean penetration rate was 0.02mm/year and none have exceeded 0.41mm total penetration. Conclusion. Since the problem of cup wear and loosening is mechanical rather than biological the long-term solutions are more likely to come from materials rather than radical changes of design of methods of component fixation

Aim

Local concentration of antibiotic at the site of infection is a major parameter for its efficiency. However, bone diffusion is poor leading either to their non-use (ex: gentamicin) or the use of high concentration (ex: vancomycin). Local administration could optimize their local concentration combined with lower side effects. We report the clinical experience and pharmacological results of an antibiotic loaded porous alumina used to replace infected bone in 4 patients.

Purpose

The fourth generation ceramic, in which zirconia is incorporated into the alumina matrix, was developed to reduce the risk of ceramic fractures. The purpose of this study was to evaluate the survivorship, clinical and radiographic results, and bearing-related failures associated with total hip arthroplasty using zirconia-toughened alumina ceramic-on-ceramic bearings over a minimum follow-up of 5 years.

Introduction

The optimal bearing for hip arthroplasty is still a matter of debate. in younger and more active patients ceramic-on-polyethylene (CoP) bearings are frequently chosen over metal-on-polyethylene (MoP) bearings to reduce wear and increase biocompatibility. However, the fracture risk of ceramic heads is higher than that of metal heads. This can cause serious issue, as ceramic fractures pose a serious complication often necessitating major revision surgery – a complication more frequently seen in ceramic-on-ceramic bearings. To date, there are no long-term data (> 20 years of follow-up) reporting fracture rates of the ceramic femoral heads in CoP bearings.

INTRODUCTION

Young patients (< 50 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.

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.

Introduction. The success of total hip arthroplasty has meant its indications have been extended to the younger more active patient. Due to the higher activity levels and increased demands of these patients, revision rates have been traditionally higher than when compared to older patients [1]. Ceramic on ceramic bearings may offer a viable long term solution as manufacturing methods have evolved resulting in improved mechanical properties, particularly of third and fourth generation ceramics. We report the outcome of primary cementless, alumina-on-alumina hip arthroplasty with a minimum 10 year follow up in 110 patients under the age of 55 years of age at time of surgery. Methods. A series of 120 consecutive total hip arthroplasties in 110 patients were performed between June 1997 and February 1999 by the two senior authors. All patients had an Osteonics ABC acetabular component and SecurFit or SecurFit Plus femoral component (Stryker Orthopaedics, Mahwah, NJ) with an alumina C-taper ceramic head (Biolox Forte, Ceramtec, Plochingen, Germany). Results. Of the 110 patients originally in the study, 4 (3.6%) patients died, 6 (5%) were lost to follow up and 4 hips (3.6%) were revised by the time of the latest follow up. Clinical information was available for 106 hips in 96 surviving patients at a minimum of ten years of follow-up, and radiographic information was available for 90 hips from the same 96 patients. The mean follow up was 11.5 years (range 10 to 13.5 years). Survivorship analysis with revision for any reason as an endpoint was 96.5% at 10 years (CI 94.5% −98.7%) using the Kaplan-Meier method. Modified mean UCLA scores improved from 6.4 (range 4 to 10) pre operatively to 9 (range 4 to 10) at latest follow up. The mean Harris Hip Score improved from 53.4 points (range 15 to 86) preoperatively, to 94.7 points (range 63 to 100) at latest follow up. All femoral stems had stable bone ingrowth, with no migration. Osteolysis was not observed around the femoral or acetabular components and there were no signs of radiological wear. 98 patients (92.4%) managed to continue with their current occupations during the follow up period whilst 5 patients (4.7%) changed occupation to work that required increased activity. Complications included 3 cases of iliopsoas tendonitis, 2 cases of squeaking, a ceramic liner chipping during insertion and sciatic nerve palsy. There were no cases of ceramic fracture in this younger, active cohort of patients. No evidence of bearing failure was demonstrated nor any signs of adverse reaction to wear debris. Conclusions. Alumina ceramic on ceramic bearings in cementless primary total hip arthroplasty show good clinical and radiological outcomes in the higher demand younger age patient. Based on these results we now support heavy occupational work and regular impact sports in these patients once they have recovered from surgery

Key Points:. Historically, 22.25, 26, 28, or 32 mm metal femoral heads were used in primary total hip arthroplasty, but innovations in materials now permit head sizes 36 mm or larger. Stability and wear of primary total hip arthroplasty are related to the diameter and material of the femoral head. Larger diameter femoral heads are associated with increased joint stability through increases in arc range of motion and excursion distance prior to dislocation. Fixation of the acetabular component may be related to the size of the femoral head, with increased frictional torque associated with large diameter heads and certain polyethylene. Linear wear of highly crosslinked polyethylenes seems unrelated to femoral head diameter, but larger heads have been reported to have higher volumetric wear. Mechanically assisted crevice corrosion at the connection between the modular femoral head and neck may be associated with the femoral head size and material. Cobalt chromium alloy, alumina ceramic composite, or oxidised zirconium femoral heads on highly crosslinked polyethylene are the most commonly used bearing surfaces, but each may have unique risks and benefits. Conclusions. At present, there is a wave of enthusiasm for the routine use of “large” (32, 36 mm, or larger) femoral heads with highly crosslinked polyethylene for the vast majority of patients having a primary THA. It may be reasonable to consider the “graduated femoral head-outer acetabular diameter system”, using 28 mm femoral heads with “smaller” acetabular components (<50 mm), 32 mm femoral heads with acetabular components 50 – 56 mm outer diameter, and 36 mm or larger femoral heads with acetabular components 58 mm or larger in diameter, to minimise both the risk of dislocation and the frictional torque. Although the linear wear of highly crosslinked polyethylene appears to be independent of head size, the reported increase in volumetric wear with large femoral heads and highly crosslinked polyethylene requires further study, and should temper the use of femoral heads 36 mm or larger in younger and more active patients. With its long and successful history, it is difficult to recommend the complete abandonment of the cobalt chromium alloy femoral head in all patients having a primary THA. Alumina ceramic or oxidised zirconium heads may be considered for younger, heavier, and more active patients, who seem to have the highest risk of trunnion corrosion. Surgeons and patients should be aware of the unique possible complications of these two newer femoral head materials

INTRODUCTION. Squeaking after total hip replacement has been reported in up to 10% of patients. Some authors proposed that sound emissions from squeaking hips result from resonance of one or other or both of the metal parts and not the bearing surfaces. There is no reported in vitro study about the squeaking frequencies under lubricated regime. The goal of the study was to reproduce the squeaking in vitro under lubricated conditions, and to compare the in vitro frequencies to in vivo frequencies determined in a group of squeaking patients. The frequencies may help determining the responsible part of the noise. METHODS. Four patients, who underwent THR with a Ceramic-on-Ceramic THR (Trident(r), Stryker(r)) presented a squeaking noise. The noise was recorded and analysed with acoustic software (FMaster(r)). In-vitro 3 alumina ceramic (Biolox Forte Ceramtec(r)) 32 mm diameter (Ceramconcept(r)) components were tested using a PROSIM(r) hip friction simulator. The cup was positioned with a 75° abduction angle in order to achieve edge loading conditions. The backing and the cup liner were cut with a diamond saw, in order to avoid neck-head impingement and dislocation in case of high cup abduction angles (Figure1). The head was articulated ± 10° at 1 Hz with a load of 2.5kN for a duration of 300 cycles. The motion was along the edge. Tests were conducted under lubricated conditions with 25% bovine serum without and with the addition of a 3. rd. body alumina ceramic particle (200 μm thickness and 2 mm length). Before hand, engineering blue was used in order to analyze the contact area and to determine whether edge loading was achieved. RESULTS. Edge loading was obtained. In-vitro, no squeaking occurred under edge loading conditions. However, with the addition of an alumina ceramic 3. rd. body particle in the contact region squeaking was obtained at the beginning of the tests and stopped after ∼20 seconds (dominant frequency 2.6 kHz). In-vivo, recordings had a dominant frequency ranging between 2.2 and 2.4 kHz. DISCUSSION. For the first time, squeaking was reproduced in vitro under lubricated conditions. In-vitro noises followed edge loading and 3. rd. body particles and despite, the severe conditions, squeaking was intermittent and difficult to reproduce. However, squeaking is probably more difficult to reproduce because the cup was cut and the head was fixed in the simulator, preventing vibration to occur. Squeaking noises of a similar frequency were recorded in-vitro and in-vivo. The lower frequency of squeaking recorded in-vivo, demonstrates a potential damping effect of the soft tissues. Therefore, the squeaking in the patients was probably related to the bearing surfaces and modified lubrication conditions that may be due to edge loading. Varnum et al reported recently (3) that all the revised squeaking patients had a neck-cup impingement with metal 3. rd. body particles. These metallic wear particles may generate squeaking as shown in vitro. However, a larger cohort of squeaking patients is needed to confirm these results

Aim. Alumina ceramic on ceramic bearings in total hip arthroplasty (THA) may reduce the prevalence of osteolysis due to its properties of low wear and chemical inertness. This is critical in the younger patient population as they place increased demands over a longer period. This study reports on the clinical and radiographic outcomes of a series of modern cementless ceramic on ceramic THA at a minimum of 10 years in this younger group. Method. A series of 120 consecutive third generation ceramic cementless THA were performed at a single centre in 110 patients from 1997 to 1999. The average age of the patients at the time of surgery was 45 years (20 to 55 years). All procedures were carried out via the posterior approach using the same implant by the two senior authors. Results. At 10 years, 4 patients had died and 6 were lost to follow-up (5%). The mean Harris Hip Score was 94.7 points. All surviving implants analysed radiographically had evidence of stable bony ingrowth, with no cases of osteolysis. Wear rates were undetectable. There were 3 revisions (2.5%). One stem was revised following periprosthetic fracture, one stem was revised to facilitate a femoral shortening osteotomy. One cup was revised for anterior impingement causing psoas tendonitis. There was one incident of intraoperative ceramic liner chipping, which was changed without complication. There were no postoperative bearing fractures. Two patients reported intermittent squeaking at extreme hip flexion and internal rotation, the hips otherwise functioned well. The survival for both components with revision for any cause was 97.5%. Conclusion. Alumina ceramic on ceramic bearings in cementless primary THA in this series have resulted in good clinical and radiographic outcomes with low wear rates and excellent function in the demanding younger patient group at 10 years

One of serious issues in total hip arthroplasty (THA) is the osteolysis which results in aseptic loosening caused by the wear particles from a polyethylene (PE) acetabular cup. In addition, oxidation degradation of PE cup resulting in the fracture or the severe wear caused by the reduction of mechanical properties in vivo is also the issue. The oxidation degradation is considered to be induced by residual free radicals generated by gamma-ray irradiation for cross-linking to reduce wear or for sterilization. In this study, (1) wear property, (2) oxidation degradation of retrieved PE and highly cross-linked PE (CLPE) cups against alumina ceramic femoral heads, and (3) the correlation between those properties were evaluated. The radiographic wear of six conventional PE cups with the mean follow-up of 19.1–23.3 years and 60 CLPE cups with the mean follow-up of 3.1–9.1 years were measured by a non-radiostereometric analysis method (Vectorworks. ®. 10.5 software package). As a retrieval analysis, 26 retrieved acetabular cups were evaluated; 16 cups were ethylene oxide gas-sterilized conventional PE cups with clinical use for 16.0–24.9 years and 10 cups were gamma-ray-sterilized CLPE cups with clinical use for 0.9–6.7 years. The linear and the volumetric wear were measured using a three-dimensional (3D) coordinate measurement machine. The shapes of unworn and worn surfaces with 15- and 30-point intervals, respectively, were measured. Oxidation degradation of the surface, sub-surface and inner for both worn and unworn parts of the retrieved cups was measured using a Fourier-transform infrared (FT-IR) spectroscopy. Oxidation indices were calculated using the peak at 1740 cm. −1. and 1370 cm. −1. according to ASTM F2012. In the radiographic analysis, the linear wear rate of CLPE cups was significantly lower than that of conventional PE cups [Fig. 1]. In the retrieval analysis, the linear wear rate of CLPE cups (mean: 0.07 mm/year) showed a 51% reduction (p = 0.002) compared to conventional PE cups (mean: 0.14 mm/year) [Fig. 2]. The retrieval and the radiographic analysis for both conventional PE and CLPE cups showed similar results (p = 0.7 and 0.1, respectively). Maximum oxidation indices for CLPE cups were similar to those of conventional PE cups regardless of the difference of clinical duration [Fig. 3]. This result is different from in vivo wear, which increases as the clinical duration. For both conventional PE and CLPE cups, the oxidation indices of subsurface were higher than those for surface. The worn parts showed higher oxidation indices than those for unworn parts. From the results, even when the free radicals were so few or absent, the oxidation degradation would be induced in vivo. In conclusion, the wear resistance for CLPE cups was greater than that for conventional PE cups from both radiographic and retrieval analyses. The in vivo oxidation degradation might not be caused by only residual free radicals. It was found that oxidation degradation of PE cups when used with alumina ceramic femoral heads is not correlated to their wear properties

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

Introduction. Alumina Ceramic liners are increasingly used in patients undergoing Total Hip Replacement (THR). The rate of fracture of ceramic liner is decreasing with improved manufacturing techniques from 1. st. to 3. rd. generation alumina-ceramic liners. We report the first case of a fracture of a modern, 4. th. generation alumina bearing ceramic liner, which incorporates a metal sheath to help avoid fracture. Our case is a 60 years old female presenting two years and three months after a bilateral total hip replacement using Stryker Trident cup, securfit stem and alumina on alumina bearing ceramic liner. Ceramic liners are commonly used, especially in young patients because of their excellent biocompatibility, low wear rate and superior tribology. Although fracture of ceramic liner is a less common complication of modern total hip arthroplasty, it is a major concern with the use of ceramic on ceramic THR, the reason being brittleness of ceramic. Cases of 3. rd. generation ceramic liner fracture have been reported which might be associated with impingement due to excessive anteversion of the socket in Asian patients who habitually squat. Habitual squatting, sitting cross legged and kneeling were not characteristic of this case. Methods. The patient presented with complains of mechanical grinding in left hip. She also reported a past history of clicking sound from left hip on extension of left hip and long stride gait. There was no history of trauma or fall. On examination she had a nonantalgic gait and left hip had audible and palpable crepitations. The range of motion on left hip was intact with no subluxation. Right hip was symptom free and examination did not detect any abnormalities. Evaluation & Results. Radiographs of left hip revealed eccentric positioning of the head [Fig. 1] within the socket and excessive anteversion of the socket, which likely caused edge-loading in extension, leading to catastrophic failure in form of fracture of ceramic liner on left hip. She was treated with revision surgery using polyethylene liner with metal head. Intra-operative findings confirmed the ceramic liner fracture [Fig. 2] and revealed impingement of the metal neck against the metal rim of the liner. Discussion & Conclusion. Although ceramic on ceramic hips have excellent wear properties, it is subject to fracture due to its brittle nature. This can lead to catastrophic failure with edge loading. In this case, the alumina-ceramic liner fractured; despite of being surrounded by a metal rim to prevent fracture. It fractured at the anterior edge, which is where it was loaded in extension. We believe that careful attention must be paid not only to inclination, but version of the socket, so as to avoid this complication. Other factors which might lead to such complication are obesity, high activity level, improper manufacturing teachniques for ceramic liners and entrapment and impingement of a micromm sized foreign body between ceramic liner and prosthetic head which initiates wear

Aim. To study the efficacy of Hydroxyapatite (HAC) Ceramic Coated hip arthroplasty. Is it suitable for the younger patient?. Methods. This series of 2390 primary HAC hip arthroplasties has been studied for up to 21 years. (569 hips over 10 years including 98 hips over 15 years) Patients are assessed by Harris Hip Score and plain X-ray. The prosthesis consists of a fully coated stem and a fully coated acetabulum. A ceramic head articulates with an acetabular liner which is either plastic (UHMW polythene) or ceramic. No cement is used. HA coated implants are physiologically fixed to cancellous bone by a process of osseointegration. Other uncemented implants are pathologically fixed by fibrous scar tissue. These two methods of fixation should be considered separately and not combined as ‘uncemented’. Results. Aseptic loosening in this series is 0.63 %. The revision rate in this series for all reasons is only 3.5%. Harris Hip Score (HHS) demonstrates excellent medium to long term results in 97% of cases (i.e. up to 20 years). Poor HHS results (36 cases: 1.51%) are mostly related to medical or other joint problems. HA fixation will outlast some of the components and wear in polythene acetabular liners can be a problem after 15 years. A sub-group of 629 hips using alumina ceramic/ ceramic bearings is successful but five components fractured (out of 1258 individual components). Wear debris from ceramic materials appears to be benign. Zirconia Toughened Alumina (ZTA) has been introduced to replace alumina and should obviate problems of ceramic implant fracture. An HA coated implant with ZTA bearings is suggested for the younger patient of either sex

INTRODUCTION. In theory, Finite Element Analysis (FEA) is an attractive method for elucidating the mechanics of modular implant junctions, including variations in materials, designs, and modes of loading. However, the credence of any computational model can only be established through validation using experimental data. In this study we examine the validity of such a simulation validated by comparing values of interface motion predicted using FEA with values measured during experimental simulation of stair-climbing. MATERIALS and METHODS. Two finite element models (FEM) of a modular implant assembly were created for use in this study, consisting of a 36mm CoCr femoral head attached to a TiAlV rod with a 14/12 trunnion. Two head materials were modelled: CoCr alloy (118,706 10-noded tetrahedral elements), and alumina ceramic (124,710 10-noded tetrahedral elements). The quasi-static coefficients of friction (µ. s. ) of the CoCr-TiAlV and Ceramic-TiAlV interfaces were calculated from uniaxial assembly (2000N) and dis-assembly experiments performed in a mechanical testing machine (Bionix, MTS). Interface displacements during taper assembly and disassembly were measured using digital image correlation (DIC; Dantec Dynamics). The assembly process was also simulated using the computational model with the friction coefficient set to µ. s. and solved using the Siemens Nastran NX 11.0 Solver. The frictional conditions were then varied iteratively to find the value of µ providing the closest estimate to the experimental value of head displacement during assembly. To validate the FEA model, the relative motion between the head and the trunnion was measured during dynamic loading simulating stair-climbing. Each modular junction was assembled in a drop tower apparatus and then cyclically loaded from 230–4300N at 1 Hz for a total of 2,000 cycles. The applied load was oriented at 25° to the trunnion axis in the frontal plane and 10° in the sagittal plane. The displacement of the head relative to the trunnion during cyclic loading was measured by a three-camera digital image correlation (DIC) system. The same loading conditions were simulated using the FEA model using the optimal value of µ derived from the initial head assembly trials. RESULTS. For both head materials, the predicted values of axial displacement of the head on the trunnion closely approximated the measured values derived from DIC measurements, with differences of −0.17% to +6.5%, respectively. Larger differences were calculated for individual components of motion for the stair climbing activity. However, the predicted magnitude of interface motion was still within 10% of the observed values, ranging from −7% to −5%. CONCLUSIONS. Our simulations closely approximated physical testing using complex loading, coming within 7% of the target values. By generating a validated computational model of a modular junctions with varying head materials, we will be able to simulate additional activities of daily living to determine micromotion and areas of peak pressure and contact stresses generated. For any figures or tables, please contact authors directly

Background/Purpose. Total hip arthroplasties (THAs) with ceramic bearings are widely performed in young, active patients and thus, long-term outcome in these population is important. Moreover, clinical implication of noise, in which most studies focused on ‘squeaking’, remains controversial and one of concerns unsolved associated with the use of ceramic bearings. However, there is little literature regarding the long-term outcomes after THAs using these contemporary ceramic bearings in young patients. Therefore, we performed a long-term study with a minimum follow-up of . 1. 5 years after THAs using contemporary ceramic bearings in young patients with osteonecrosis of the femoral head (ONFH) less than fifty. Materials and Methods. Among sixty patients (71 hips) with a mean age of 39.1 years, 7 patients (7 hips) died and 4 patients (4 hips) were lost before 15-year follow-up. The remaining 60 hips were included in this study with an average follow-up period of 16.3 years (range, 15 to 18). All patients underwent cementless THA using a prosthesis of identical design and a 28-mm third-generation alumina head by single surgeon. The clinical evaluations included the modified Harris hip score (HHS), history of dislocation and noise around the hip joint: Noise was classified into squeaking, clicking, grinding and popping and evaluated at each follow-up. Snapping was excluded through physical examination or ultrasonography. Radiographic analysis was performed regarding notching on the neck of femoral component, loosening and osteolysis. Ceramic fracture and survivorship free from revision were also evaluated. Results. The mean Harris hip score improved from 55.3 to 95.5 points (range, 83 to 100) at the time of the final follow-up. Seventeen patients (34.7%) reported noise around the hip joint: “squeaking” in one and “clicking” in 16 patients. Notching on the neck of femoral component suggesting impingement between neck and ceramic liner was demonstrated in 9 hips (15%) at average of 6.9 years postoperatively and located at 2 to 3.5 mm distal to edge of ceramic head. Although no chip fracture of ceramic ‘liner’ occurred, notching was associated with “clicking” sound (p<0.01). One patient who reported clicking sound underwent a revision THA because of ceramic ‘head’ fracture. Loosening, osteolysis or dislocation was not observed in any hip and survivorship free from revision at 5 years was 98%. Conclusion. Cementless THAs using 28-mm contemporary alumina ceramic head demonstrated excellent long-term outcome in young, active patients with ONFH. Despite this encouraging result, however, we remain concerned about ‘clicking’ sound, because we did observe it associated with notching on the neck of stem. Acknowledgement. This work was supported by Institute for Information & communications Technology Promotion (IITP) grant funded by the Korea government (MSIP) (#B0101-14-1081)

Introduction. Ceramic total knee arthroplasty (TKA) was introduced as a new-generation of knee prostheses in clinical practice, and are expected to reduce polyethylene wear due to its resistance to abrasion and lubrication. In 1992, we developed a cruciate retaining LFA-I total knee prosthesis (KYOCERA Medical Co., Japan), which comprises an alumina ceramic femoral component and a titanium-alloy tibial component with a polyethylene insert. The purpose of this study was to evaluate clinical results in rheumatoid patients who were treated with the alumina-ceramic LFA-I prosthesis with a minimum 15-year follow-up period. Methods. A total of 70 primary TKAs were performed in 51 patients between 1993 and 1996 using the cemented alumina-ceramic LFA-I prosthesis. Sixteen of these patients (20 knees) had died by the time of this study, of causes unrelated to the index arthroplasty, and 11 patients (16 knees) were lost to the follow-up. The remaining 34 knees were clinically and radiographically evaluated in the present study. The average follow-up time was 16.7 years. The average age of the patients was 58.2 years at the time of the operation. The clinical assessment was conducted with the Hospital for Special Surgery Knee rating score and the Knee Society scoring system. The component alignment and bone-implant interface were evaluated according to the Knee Society Roentgenographic Evaluation System. Results. The cumulative survival rate for revision for any reason at 15 years was 94.1%. The mean postoperative range of motion was 115.3 degrees at the time of the most recent follow-up. The mean postoperative knee score was 90.1 and 84.7 using the Knee Society and the Hospital for Special Surgery rating systems, respectively. Reoperations had been required on two knees due to loosening and on one knee due to infection. Periprosthetic radiolucencies or osteolysis were present in six knees. All lesions occurred around the prosthetic rim; 3 lesions at the anterior femoral flange, 5 lesions at the medial tibia, 2 lesions at the lateral tibia, and 1 lesion at the anterior tibia. These implants did not migrate, subside, or have circumferential radiolucencies that would indicate radiographic loosening. Discussion. In this series of patients with rheumatoid arthritis, the alumina-ceramic LFA-I prosthesis has performed well for the average 16.7 years of follow-up. It is not possible to draw any conclusions regarding the superiority of the ceramic prosthesis with respect to wear and survivability, however, the lack of a ceramic breakage with this anatomical design has encouraged us to continue to use this ceramic prostheses

Two types of ceramic materials currently used in total hip replacements are third generation hot isostatic pressed (HIPed) alumina ceramic (commercially known as BIOLOX®forte, CeramTec) and an alumina matrix composite material consisting of 75% alumina, 24% zirconia, and 1% mixed oxides (BIOLOX®delta, CeramTec). The aim of this study is to compare BIOLOX delta femoral heads to BIOLOX forte femoral heads revised within 2 years in vivo. Ceramic bearings revised at one center from 1998 to 2010 were collected (61 bearings). BIOLOX delta heads (n=11) revised between 1–33 months were compared to BIOLOX forte femoral heads with less than 24 months in vivo (n=20). The surface topography of the femoral heads was measured using a chromatically encoded confocal measurement machine (Artificial Hip Profiler, RedLux Ltd.). The median time to revision for BIOLOX delta femoral heads was 12 months, compared to 13 months for BIOLOX forte femoral heads. Sixteen out of 20 BIOLOX forte femoral heads and 6 out of 11 BIOLOX delta femoral heads had edge loading wear. The average volumetric wear rate for BIOLOX forte was 0.96 mm3/yr (median 0.13 mm3/yr), and 0.06 mm3/yr (median 0.01 mm3/yr) for BIOLOX delta (p=0.03). There was no significant difference (p>0.05) in age, gender, time to revision or femoral head diameter between the two groups. Early results suggest less volumetric wear with BIOLOX delta femoral heads in comparison to BIOLOX forte femoral heads

Despite 46 years clinical experience with ceramic-on-ceramic (COC) hip bearings, there is no data on what constitutes a successful long-term wear performance. There have been many studies of short-term failures (Dorlot, 1992; Nevelos, 2001, Walters, 2004). One retrieval study using optical-CMM technology (OCM) documented volumetric wear-rates ranging up to 7mm. 3. /year on femoral heads (Esposito 2012). It was noted that 83% of these revisions showed stripe damage within 3–4 years. The supposition would appear to be that these were bearing-related failures. Our selected COC case for this study was particularly interesting, a female patient having her index surgery performed at age 17 and revised at age 49 (following onset of hip pain). This patient led an active lifestyle, went dancing multiple times per week, and was mother to three children. The 38mm Autophor. TM. THA (left hip) was eventually revised due to the cup painful migrating (Fig. 1: 32-years follow-up). Radiographs showed cup inclination at approximately 19. °. Impingement marks were noted on the CoCr neck and collared stem (Fig. 2). Implant geometry and form factors were analyzed by standard contour measurement (CMM) while SEM and EDS imaging provided wear topography and evidence of metal contaminants. Linear and volumetric wear in head and cup were studied by OCM at Redlux (Southampton, UK). The head's main wear-pattern consisted of two overlapping circular areas (Fig. 3). The narrowest margin made by the wear-pattern was used to define the superior aspect of the head. By light microscopy, the superior main-wear zone covered 1490–1680mm. 2. area while the total bi-lobed area covered larger 2170mm. 2. area. OCM analysis delineated the same bi-lobed appearance of head wear with the superior worn area assessed at 1365mm. 2. The cup revealed a more extensive wear pattern that circumnavigated its surface. The black staining identified by EDS imaging in the cup revealed Co and Cr elements. By OCM technique the head volumetric wear was 179 mm³ and the cup was 214mm. 3. (Fig. 4), i.e. 20% greater than head. Volumetric wear-rate averaged 12.3mm. 3. per year for this pioneering alumina ceramic. This first demonstration of long-term, COC volumetric wear provides the foundation for retrieval and simulator studies alike. Our patient represented a “worst-case” scenario for hip-replacement surgery, due to extreme youth and long-term sporting life. While the superior wear pattern was not totally contained within the cup (Fig. 3), her implant positioning was clearly adequate. Nevertheless both cup edge-wear and CoCr contamination indicated this patient experienced habitual impingement, i.e. alumina cup rim wearing against CoCr femoral neck (Fig. 2). The head wear-pattern was distinctly bi-lobed but OCM images showed the majority of wear was in the superior hemisphere as noted in MOM retrievals (Clarke, 2013). The head wear-rate in this pioneering “Mittelmeier” THA averaged 5.6mm³/year over 32-years of follow-up. This appeared directly comparable to ceramic head wear measured with the same OCM-technique in modern ceramic THA (Esposito, 2012: 0.1 to 7mm. 3. /year). This indicated to us that COC wear rates of the order 10–14mm. 3. /year represented an acceptable “normal” level of performance in young and active individuals