Does Biolox Delta ceramic reduce the rate of component fractures in total hip replacement?

Material-Intrinsic NIR-Fluorescence Enables Image-Guided Surgery for Ceramic Fracture Removal

Hip arthroplasty effectively treats advanced osteoarthritis and is therefore entitled as "operation of the 20th century." With demographic shifts, the USA alone is projected to perform up to 850 000 arthroplasties annually by 2030. Many implants now feature a ceramic head, valued for strength and wear resistance. Nonetheless, a fraction, up to 0.03% may fracture during their lifespan, demanding complex removal procedures. To address this, a radiation-free, fluorescence-based image-guided surgical technique is presented. The method uses the inherent fluorescence of ceramic implant materials, demonstrated through chemical and optical analysis of prevalent implant types. Specifically, Biolox delta implants exhibited strong fluorescence around 700 nm with a 74% photoluminescence quantum yield. Emission tails are identified extending into the near-infrared (NIR-I) biological transparency range, forming a vital prerequisite for the label-free visualization of fragments. This ruby-like fluorescence could be attributed to Cr within the zirconia-toughened alumina matrix, enabling the detection of even deep-seated millimeter-sized fragments via camera-assisted techniques. Additionally, fluorescence microscopy allowed detection of µm-sized ceramic particles, enabling debris visualization in synovial fluid as well as histological samples. This label-free optical imaging approach employs readily accessible equipment and can seamlessly transition to clinical settings without significant regulatory barriers, thereby enhancing the safety, efficiency, and minimally invasive nature of fractured ceramic implant removal procedures.

Ceramic-on-Ceramic or Metal-on-Polyethylene: The Bearing of Choice after Ceramic Component Fracture in Total Hip Arthroplasty along with Concise Follow-Up of the Previous Cohort

OBJECTIVE

We previously reported the questionable result of reoperation using metal-on-polyethylene (MoP) bearing after the fracture of the ceramic component. After the report, we abandoned the use of MoP; instead, we used ceramic-on-ceramic (CoC) bearing. This report aimed to present the outcome of reoperation to CoC bearing after ceramic component failures along with the longer-term outcome of the previously reported cohort with an MoP bearing.

RESULTS

The mean follow-up of the MoP cohort was extended from 4.3 years to 8.8 years. Metallosis had occurred in three of nine patients of the previous cohort, which all required re-reoperations. Two hips from 11 patients with revision to CoC had re-reoperations due to ceramic liner fracture and non-union of the osteotomized fragment, respectively. No metallosis and wear occurred in the cohort revised with CoC articulation. Otherwise, there were no adverse changes in radiographs and no impairment in functions.

METHODS

We conducted an extended prospective evaluation of a previous cohort consisting of six head fractures and three liner fractures. In this cohort, the patients underwent a bearing change to metal-on-polyethylene. Additionally, we retrospectively analyzed 11 cases of third-generation ceramic bearing fractures, comprising nine head fractures and two liner fractures. These cases were subsequently treated with a bearing change to fourth-generation CoC. We assessed clinical and radiological outcomes, including complication rates, in both groups.

CONCLUSION

We recommend the latest CoC as the bearing of choice in reoperation after the fracture of ceramic components. In the case of an MoP bearing after the ceramic component fracture, the risk of metallosis seemed high in the early postoperative period.

FEM wear prediction of ceramic hip replacement bearings under dynamic edge loading conditions

Hard-on-Hard hip implants, specifically ceramic tribo-pair, have produced the highest in-vivo wear resistance, biocompatibility, superior corrosion resistance, and high fracture toughness. However, this ceramic tribo-pair suffers from edge loading, sharply increasing wear and accelerating early implant failures due to micro-separation. Even though in-vitro studies have tested the occurrence of wear due to dynamic edge loading, the Finite Element Method (FEM) gives the advantage of accurately estimating the wear, minimizing the experimental time and cost. A new fundamental FEM model is developed to predict wear for ceramic hip replacement bearings under dynamic edge loading conditions for a fixed separation and fixed inclination angle. The model is directly validated with the existing hip simulator data up to 3 million cycles in terms of wear depth, wear scar and volumetric wear rate. The results from the model show that the accuracy in wear prediction was more than 98% for the wear depth and volumetric wear rate for the dynamic edge loading condition. A stripe wear scar is captured, depicting the edge loading conditions. The developed model from this study can predict wear under pure standard and dynamic edge loading conditions.

Updates on Biomaterials Used in Total Hip Arthroplasty (THA)

One of the most popular and effective orthopedic surgical interventions for treating a variety of hip diseases is total hip arthroplasty. Despite being a radical procedure that involves replacing bone and cartilaginous surfaces with biomaterials, it produces excellent outcomes that significantly increase the patient's quality of life. Patient factors and surgical technique, as well as biomaterials, play a role in prosthetic survival, with aseptic loosening (one of the most common causes of total hip arthroplasty failure) being linked to the quality of biomaterials utilized. Over the years, various biomaterials have been developed to limit the amount of wear particles generated over time by friction between the prosthetic head (metal alloys or ceramic) and the insert fixed in the acetabular component (polyethylene or ceramic). An ideal biomaterial must be biocompatible, have a low coefficient of friction, be corrosion resistant, and have great mechanical power. Comprehensive knowledge regarding what causes hip arthroplasty failure, as well as improvements in biomaterial quality and surgical technique, will influence the survivability of the prosthetic implant. The purpose of this article was to assess the benefits and drawbacks of various biomaterial and friction couples used in total hip arthroplasties by reviewing the scientific literature published over the last 10 years.

Outcomes of Ceramic-On-Ceramic Bearing Total Hip Arthroplasty: A Minimum 10-Year Follow-Up Study

BACKGROUND

Although the fourth generation of ceramics has demonstrated excellent clinical results 5 to 6 years postoperatively, concerns over ceramic fracture and squeaking persist and longer-term follow-up (minimum 10 years) studies are warranted. Our study aimed to evaluate the minimum 10-year clinical outcomes and bearing-specific complications of ceramic-on-ceramic (CoC) total hip arthroplasties.

METHODS

We retrospectively evaluated all patients who underwent primary delta CoC total hip arthroplasty in our institution between January 2004 and February 2013. Demographics, surgical techniques, complications, patient-reported outcomes, and radiographic outcomes were collected and analyzed. For continuous variables, the comparison between groups was conducted using a one-way analysis of variance. Of all 235 patients included in the study, 70.5% were women (190 hips). The mean follow-up period was 12 years (range, 10 to 18). The femoral head sizes of 28- mm, 32 mm, and 36 mm were used in 50, 26, and 197 cases, respectively. Mean acetabular inclination and anteversion angles were 39.2 ± 7.1° and 14.9 ± 3.5°.

RESULTS

There were 5 hips revised at a mean 4.6 years (range, 0.1 to 7.1). One revision was squeaking-related. Squeaking was also reported by 8 other patients, but did not require revision. Other reasons for revision were early infection in 2 cases, stem loosening in 1 case, and stem fracture in 2 cases. The survival analysis for any causes for revision as an endpoint was 96.7% (95% confidence interval 0.313%-2.57%).

CONCLUSION

We report excellent mean 12-year follow-up results regarding the complications and survivorship of the fourth generation CoC bearings.

A Nomogram That Characterizes a Patient's Odds of Developing Squeaking After Fourth-generation Ceramic-on-ceramic THA

BACKGROUND

Although ceramic-on-ceramic (CoC) bearings result in the lowest wear rate of any bearing combination, postoperative squeaking remains worrisome. However, data concerning squeaking in long-term follow-up studies are still lacking, especially for fourth-generation CoC THA.

QUESTIONS/PURPOSES

(1) After keeping the prosthesis in place for 10 years, what percentage of patients treated with fourth-generation CoC THA implants report squeaking, and are there points in time when squeaking occurs more frequently? (2) What are the characteristics, association with hip function, and factors associated with squeaking? (3) Can we create a nomogram that characterizes a patient's odds of experiencing squeaking based on the factors associated with it?

METHODS

Between January 2009 and December 2011, 1050 patients received primary THAs at our institution, 97% (1017) of whom received fourth-generation CoC THAs because this was the preferred bearing during this period. Of the 1017 eligible patients, 5% (54) underwent THAs performed by low-volume surgeons, 3% (30) were implanted with cemented prostheses, 2% (22) died, 1% (10) were immobile, 1% (six) underwent revision surgery, and 17% (169) were lost to follow-up before 10 years, leaving 726 patients for analysis here at a mean of 11 ± 1 years. In the study cohort, 64% (464) were male and 36% (262) were female, with a mean age of 44 ± 13 years at primary THA. We extracted data about articular noise from follow-up records in our institutional database and used a newly developed questionnaire to ascertain the percentage of patients who reported squeaking at the latest follow-up interval. Although not validated, the questionnaire was modeled on previous studies on this topic. The longitudinal pattern for squeaking was explored to find timepoints when squeaking occurs more frequently. Based on the questionnaire data, we calculated the percentages of frequent, reproducible, and avoidable squeaking. Hip function was evaluated with the Harris Hip Score and WOMAC score and compared between the squeaking and nonsqueaking groups. Factors associated with squeaking, which were examined in a multivariate analysis, were used to develop a nomogram.

RESULTS

At 10 years, 16% (116 of 726) of patients reported squeaking. Two squeaking peaks were determined, at 0 to 1 year and 8 to 10 years. Frequent, reproducible, and avoidable squeaking accounted for 42% (36 of 86), 20% (17 of 86), and 41% (35 of 86), respectively. The mean Harris Hip Score (93 ± 4 versus 94 ± 5; p = 0.81) and WOMAC score (16 ± 13 versus 15 ± 13; p = 0.23) did not differ between patients with squeaking and those without. After controlling for potential confounding variables such as etiology and head offset, we found that patients younger than 46 years (odds ratio 2.5 [95% confidence interval 1.5 to 5.0]; p < 0. 001), those who were male (OR 2.0 [95% CI 1.1 to 3.5]; p = 0.04), those having a total flexion and extension arc of less than 50° (OR 2.0 [95% CI 1.2 to 3.3]; p = 0.02), and those with the Corail hip implant (OR 4.1 [95% CI 2.1 to 7.7]; p < 0. 001) were more likely to report squeaking. We created a nomogram that can be used at the point of care that can help clinicians identify patients at a higher risk of experiencing squeaking; this nomogram had good performance (area under the receiver operating characteristic curve of 77%).

CONCLUSION

As a potential late complication, squeaking after fourth-generation CoC THA is of concern and may be related to increased stripe wear. We recommend that surgeons use this nomogram to assess the odds of squeaking before selecting a bearing, especially in patients at high risk, to facilitate shared decision-making and improve patient satisfaction. Future external validation of the model is still needed to enhance its applicability.Level of Evidence Level III, therapeutic study.

Mean 16-Year Results of Total Hip Arthroplasty with Alumina Ceramic Femoral Heads on Highly Cross-Linked Polyethylene in Patients 50 Years or Less

BACKGROUND

Highly cross-linked polyethylene (HXLPE) is a widely used bearing surface in total hip arthroplasty (THA); long-term results in young patients are limited. We previously demonstrated excellent results in HXPLE on cobalt-chrome femoral heads at 15-year mean follow-up. The purpose of the present study was to investigate polyethylene wear rates, implant survivorships, wear-related revisions, and patient-reported outcomes (PROs) in a young patient cohort who had alumina ceramic on HXPLE coupling at an average 16-year follow-up.

METHODS

This was a retrospective study of 128 hips who underwent THA with HXLPE on alumina ceramic bearings between March 1, 2004, and April 15, 2007. Patient mean age was 38 years (range, 13 to 50). All THAs utilized HXPLE liners with alumina ceramic heads. The University of California, Los Angeles (UCLA) Activity Score and modified Harris Hip Scores (mHHS) were collected pre-operatively and at each follow-up. Martell Hip Analysis Suite was used for wear calculations.

RESULTS

At average 16 years (range, 13 to 18), aseptic revision survivorship was 93.3% and osteolysis/wear survivorship was 99.2%. The mean linear wear rate was 0.0191 millimeters (mm)/year and mean volumetric wear rate was 19.43 mm³/year, both of which were clinically undetectable. We observed excellent patient reported outcomes with a significant increase in mean mHHS (43.6 to 87.4, P <0.0001) and UCLA Activity Scores (4.0 to 6.0, P <0.0001). There were no statistically significant differences in PROs or wear rates between ceramic and cobalt-chrome groups.

CONCLUSION

At mean 16-year follow-up, young patients who had HXLPE on ceramic coupling had excellent wear properties, PROs, and acceptable survivorships.

Damage analysis of retrieved BioloxⓇdelta components used in hard and soft bearings

This retrieval study included 43 Biolox delta explants (18 CoC, 25 CoP). Implants were examined macroscopically, whereby damage was evaluated using a semi quantitative scoring system. Confocal microscopy was used to examine wear related damage patterns of the articulating surfaces. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) was used to analyze wear marks on the implant surface and wear debris in periprosthetic tissue samples. Raman spectroscopy and X-ray diffraction (XRD) were used to quantify monoclinic zirconia fractions. On all components, in vivo wear resulted predominantly in different damage patterns caused by metal transfer. In CoC bearings stripe wear was additionally detected, and some implants underwent severe damage due to component breakage. The wear scores were higher for CoC components, with no differences between the scores for CoC heads and liners. Wear features caused comparable roughening on implants from CoC and CoP bearings. SEM studies demonstrated that most wear marks were caused by metal debris released from implant components. Grain pull-out was observed in stripe wear regions. Monoclinic phase shift was observed in a similar quantity on components from CoP and CoC bearings. The increase of monoclinic zirconia content around metal deposits was minimal and was more pronounced in areas of stripe wear. The results of this study indicate, that ZTA components in general undergo minimal wear in both, CoC and CoP bearings, however, it is more pronounced in the former. Metal deposits, as the most common wear feature, have no significant effect on monoclinic phase transition. STATEMENT OF SIGNIFICANCE: In this paper, we classify all damage patterns macroscopically according to an established scoring system and assess them regarding surface roughness (confocal microscopy) and monoclinic phase content (Raman spectroscopy) in order to derive the severity for patients. We compare hard-hard and hard-soft bearings and relate damage patterns with metal transfer based on SEM/EDS examinations. Furthermore, we work out correlations between patient-specific data, cause of revision and the physical condition of each individual sample Our cohort consists of 43 Biolox delta retrievals, a comparatively large quantity. In addition, we address current topics such as metal transfer and, based on the classification of damage patterns, provide incentives and/or meaningful focal points for further research.

Are CPR (Contact Patch to Rim) distance anomalies associated with the occurrence of abnormal noises from ceramic-on-ceramic THA?

INTRODUCTION

The ceramic-on-ceramic couple in total hip arthroplasties (THA) has the advantage of excellent wear resistance and the bioinert nature of its debris. Noise occurring from this friction torque is a common complication, the contributing factors of which are debated. The noise is caused by a lack of lubrication, due in most part to the positioning of the acetabular cup. The study of metal-on-metal couples identified that the calculation of the Contact Patch to Rim (CPR) distance provides information on lubrication defects and also that it is correlated with the wear of metal-on-metal implants. This CPR distance is not recognized to be correlated with the occurrence of noise for the ceramic-on-ceramic couple at a caliber ≤ 36mm. We therefore conducted a retrospective case-control study to assess: 1) The influence of the CPR distance on noise occurrence; 2) Whether other factors associated to noise occurrence exist?

HYPOTHESIS

Our hypothesis was that a low CPR distance was correlated with noise occurrence.

METHOD

This was a case-control study with 3 controls for each case, analyzing 21 THAs (21 patients) with noise compared to 63 THAs without noise (63 patients) matched for age, sex and body mass index. These patients were taken from a continuous retrospective series of 96 patients for 104 total hip arthroplasties (THA) with a single operator and 4^th generation Biolox Delta ceramic-on-ceramic single implant, performed between 2007 and 2012. The calculation of the CPR distance was then performed for both groups using measurements of inclination angles, anteversion angles, and implant data regarding the head/insert contact angle, head/insert diameter and clearance.

RESULTS

At the mean follow-up of 7.1 years±1.2 [5 to 9.6], the mean CPR distance was lower in the noise group 10mm±3.3 [3.8 to 16.4] than in the control group 14.8mm±4.3 [7.3 to 24.4] (p=0.0007). The mean inclination angle was higher in the noise group 45.1°±7.8 [31 to 62] than in the control group 41.2°±7.2 [26 to 56] (p=0.04). The occurrence of noise was independent of anteversion, head caliber, cup diameter, neck length and stem size, and stem type (standard or lateralized).

CONCLUSION

A low CPR distance was correlated with the occurrence of noises, similarly a steep inclination was correlated with the occurrence of noises.

LEVEL OF EVIDENCE

III; Retrospective case-control study.

The occurrence of squeaking under wear testing standards for ceramic on ceramic total hip replacements

Ceramic on ceramic total hip replacement clinical reports may on occasion note a noise or squeaking. There is much debate on whether this is an actual concern, but some medical centres want to avoid any possible negative impact on the patients' wellbeing due to the noise generated. The aim of this study was to determine what sound frequencies can be picked up from hip testing standards for ceramic on ceramic under different lubrication conditions. The ISO-14242-1 (35° cup angle) and ISO-14242-4 (55° cup angle with a 4 mm translational mismatch) standards were used for testing with dry, water and serum lubrication conditions up to 10000 cycles. No sound was detected for water and serum conditions under standard walking (ISO-14242-1) testing. An audible noise with a frequency range of 0.4-0.8 kHz was picked up within 600 cycles under water and edge loading (ISO-14242-4) conditions. All dry testing produced a high pitch squeak when the frequency was higher than 2 kHz. One sample under dry edge loading conditions had an audible noise of 0.8 kHz, considered not as squeaking, as it was not high pitch. Dry testing for both, standard walking (ISO-14242-1) and edge loading (ISO-14242-4) conditions, which resulted in a high pitch noise, had a frequency range of 2-8 kHz and 5-9 kHz respectively. One sample tested with edge loading and serum produced a faint squeak noise after 6000 cycles with a frequency of 7 kHz. Edge loading due to ISO-14242-4 conditions had an increased torque which may be playing a role in increased friction leading to noise. Edge loading conditions were more prone to the generation of audible noise and squeaking whilst under lubricated conditions.

Primary Total Hip Arthroplasty with Ceramic-on-Ceramic Articulations: Analysis of a Single-center Series of 1,083 Hips at a Minimum of 10-Year Follow-Up

BACKGROUND

There are limited long-term results of using ceramic-on-ceramic bearings (COC) in total hip arthroplasty (THA) in a large number of patient cohorts. The purpose of this study was to evaluate the minimum 10-year clinical and radiological outcomes and survivorship in a single surgeon series of CoC-THA.

METHODS

Among the 1,039 patients (1,391 hips) who underwent primary THA at our institution between 2008 and 2011, 49 patients (69 hips) experienced paralysis or death, and 194 patients (239 hips, 19%) were lost to follow-up. The remaining 796 patients (1,083 hips) were assessed at a mean of 11 years (range, 10 to 13 years) using the modified Harris hip score (mHHS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and a questionnaire on articular noises. Survival analysis was used to estimate the survivorship. Radiological evaluation was performed on 869 hips at the final follow-up.

RESULTS

Survivorship at 11 years was 98.3% for revision or aseptic loosening, and 98.2% for re-operation. At the final follow-up, the mean mHHS and WOMAC scores were 93 (range, 12 to 100) and 14.4 (range, 3 to 66), respectively. There were 131 (12%) hips experienced squeaking, but no patient required revision. No fracture of the ceramic was observed. Radiological evaluation at the final follow-up revealed that three (0.3%) hips exhibited loosening, two (0.2%) had femoral osteolysis, 81(9.3%) acquired radiolucencies, and 35 (4%) showed heterotopic ossification.

CONCLUSION

This ceramic-on-ceramic bearing for THA had a high survivorship and excellent functional outcomes for at least 10 years.

Bioactive Inorganic Materials for Dental Applications: A Narrative Review

Over time, much attention has been given to the use of bioceramics for biomedical applications; however, the recent trend has been gaining traction to apply these materials for dental restorations. The bioceramics (mainly bioactive) are exceptionally biocompatible and possess excellent bioactive and biological properties due to their similar chemical composition to human hard tissues. However, concern has been noticed related to their mechanical properties. All dental materials based on bioactive materials must be biocompatible, long-lasting, mechanically strong enough to bear the masticatory and functional load, wear-resistant, easily manipulated, and implanted. This review article presents the basic structure, properties, and dental applications of different bioactive materials i.e., amorphous calcium phosphate, hydroxyapatite, tri-calcium phosphate, mono-calcium phosphate, calcium silicate, and bioactive glass. The advantageous properties and limitations of these materials are also discussed. In the end, future directions and proposals are given to improve the physical and mechanical properties of bioactive materials-based dental materials.

Long-term survivorship of an exchangeable-neck hip prosthesis with a Ti-alloy/Ti-alloy neck-stem junction

INTRODUCTION

Breakage of exchangeable-neck (EN) and adverse local tissue reactions (ALTRs) to neck-stem junction (NSJ) damage products are responsible for increasing the revision rate of EN hip prostheses. We investigated the survivorship of an EN hip prosthesis including a NSJ with both components made of titanium alloy (Ti-alloy/Ti-alloy) to assess whether, and to what extent, EN breakage and NSJ damage affected implant survivorship.

MATERIALS AND METHODS

Using data from a hip replacement registry, we determined survivorship of 2857 EN prostheses. Long-offset configurations of head and EN were implanted in heavy (> 90 kg) patients only in 23 hips. We investigated under which conditions EN breakages or ALTRs occurred. We also measured titanium (Ti) and vanadium (V) blood concentrations in 24 patients with a unilateral well-working prosthesis.

RESULTS

The 17-year survival rates for any reason and aseptic loosening of any component were 88.9% (95%CI 87.5-90.1; 857 hips at risk) and 96.9% (95%CI 96.0-97.6), respectively. There were two cases of EN breakage and one case of ALTR (metallosis), due to rim-neck impingement, out of 276 revisions. After an average period of 9.8 years (range 7.8-12.8 years), the maximum Ti and V blood concentrations in patients with a well-working prosthesis were 5.0 µg/l and 0.16 µg/l, respectively.

CONCLUSION

The present incidence of EN breakage or ALTR is lower than those reported in other studies evaluating EN hip prosthesis survivorship. This study suggests that (i) the risk of EN breakage is reduced by limiting the use of long-offset configurations in heavy patients and (ii) Ti-alloy/Ti-alloy NSJ damage products do not promote ALTR nor significantly alter the rate of implant loosening. Since design decisions and implant configuration determine the NSJ strength, the NSJ strength in working conditions must be thoroughly investigated to proper define the clinical indications for any EN design.

Lower Rates of Ceramic Femoral Head Use in Non-White Patients in the United States, a National Registry Study

BACKGROUND

The purpose of our study was to investigate the association of race and ethnicity with the use of the newest technology and postoperative outcomes in total hip arthroplasty (THA) using the American Academy of Orthopaedic Surgeons (AAOS) American Joint Replacement Registry (AJRR).

METHODS

Adult THA procedures were queried from the AJRR from 2012 to 2020. A mixed-effects multivariate regression model was used to evaluate the association of race and ethnicity with the use of the newest technology (ceramic femoral head, dual-mobility implant, and robotic assist) at 30-day, and 90-day readmission. A proportional subdistribution hazard model was used to model a risk of revision THA.

RESULTS

There were 85,188 THAs with complete data for an analysis of outcomes and 103,218 for an analysis of ceramic head usage. The median length of follow-up was 37.9 months (interquartile range [IQR] 21.6 to 56.3 months). In multivariate models, compared to White non-Hispanic patients, Black (odds ratio [OR] 0.79, 95% confidence interval [CI] 0.69-0.92, P < .001), Hispanic (OR 0.76, CI 0.59-0.99, P = .037), Asian (OR 0.74, CI 0.55-1.00, P = .045), and Native American (OR 0.52, CI 0.30-0.87, P = .004) patients all had significantly lower rates of ceramic head use in THA. Compared to White non-Hispanic patients, Asian (hazard ratio [HR] 0.39, CI 0.18-0.86, P = .008) and Hispanic (HR 0.43, CI 0.19-0.98, P = .043) patients had significantly lower rates of revision. No differences in 30-day or 90-day readmission rates were seen.

CONCLUSION

Black, Hispanic, Native American, and Asian patients had lower rates of ceramic head use in THA when compared to White patients. These differences did not translate into worse clinical outcomes on a short-term follow-up. In fact, Asian patients had lower revision rates compared to non-Hispanic White patients. Additional study is necessary to evaluate the long-term consequence of lower ceramic head use in non-White patients in the United States.

A case-driven hypothesis for multi-stage crack growth mechanism in fourth-generation ceramic head fracture

BACKGROUND

Ceramic bearings are used in total hip arthroplasty due to their excellent wear behaviour and biocompatibility. The major concern related to their use is material brittleness, which significantly impacts on the risk of fracture of ceramic components. Fracture toughness improvement has contributed to the decrease in fracture rate, at least of the prosthetic head. However, the root cause behind these rare events is not fully understood. This study evaluated head fracture occurrence in a sizeable cohort of patients with fourth-generation ceramic-on-ceramic implants and described the circumstances reported by patients in the rare cases of head fracture.

METHODS

The clinical survivorship of 29,495 hip prostheses, with fourth-generation ceramic bearings, was determined using data from a joint replacement registry. The average follow-up period was 5.2 years (range 0.1-15.6). Retrieval analysis was performed in one case for which the ceramic components were available.

RESULTS

Clinical outcomes confirmed the extremely low fracture rate of fourth-generation ceramic heads: only two out of 29,495 heads fractured. The two fractures, both involving 36 mm heads, occurred without a concurrent or previous remarkable trauma. Considering the feature of the fractured head, a multi-stage crack growth mechanism has been hypothesized to occur following damage at the head-neck taper interface.

CONCLUSIONS

Surgeons must continue to pay attention to the assembly of the femoral head: achieving a proper head seating on a clean taper is a prerequisite to decrease the risk of occurrence of any damage process within head-neck junction, which may cause high stress concentration at the contact surface, promoting crack nucleation and propagation even in toughened ceramics.

Improving the Endoprosthesis Design and the Postoperative Therapy as a Means of Reducing Complications Risks after Total Hip Arthroplasty

One of the most high-tech, efficient and reliable surgical procedures is Total Hip Arthroplasty (THA). Due to the increase in average life expectancy, it is especially relevant for older people suffering from chronic joint disease, allowing them to return to an active lifestyle. However, the rejuvenation of such a severe joint disease as osteoarthritis requires the search for new solutions that increase the lifespan of a Total Hip Replacement (THR). Current trends in the development of this area are primarily focused on the creation of new materials used in THR and methods for their processing that meet the requirements of biocompatibility, long-term strength, wear resistance and the absence of an immune system response aimed at rejection. This study is devoted to the substantiation of one of the possible approaches to increase the reliability and durability of THR, based on the improvement of the implant design and postoperative rehabilitation technology, potentially reducing the risk of complications in the postoperative period.

Ceramic-on-metal coupling in THA: long term clinical and radiographic outcomes using two different short stems

BACKGROUND

Hip prosthetic replacement surgery is the gold standard for patients affected by symptomatic osteoarthritis. The ceramic-on-metal hybrid hard-on-hard bearing was initially launched on the market with the purpose of reducing adhesive and corrosion wear, loss of metal debris and ions and risk of fracture and squeaking. However, this bearing was withdrawn from the market, in the apprehension of local and systemic toxicity. The aim of this study is to evaluate the reliability and safety of ceramic-on-metal bearing at long term follow-up.

METHODS

From 2 cohorts of patients suffering of hip osteoarthritis who underwent total hip arthroplasty using ceramic-on-metal bearing with two different short stems, 19 of the GROUP A and 25 of the GROUP B were suitable for this study. All patients were compared clinically using the Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), visual analogue scale (VAS), 12-item Short Form Health Survey (SF12P/M), and radiographically. Blood samples were collected in order to evaluate chromium and cobalt ions level. The two groups were compared in terms of metal ions blood levels, and finally all the implanted prostheses were compared with a healthy control group.

RESULTS

All the implanted stems were well-positioned and osseointegrated at a mean follow-up of 114 months. Improvements were observed for all clinical scores comparing preoperative and postoperative values in both groups. Radiographic evaluation showed a good ability to restore proper articular geometry. Chromium and cobalt ion analysis revealed values below the safety threshold except for 1 case in GROUP A (cup malposition) and 2 cases in GROUP B (6.1%). No revision occurred.

CONCLUSIONS

Ceramic-on-metal bearing is safe and reliable at long term follow-up in association to short stems arthroplasty, if the implant is correctly positioned. Chromium and cobalt metal ions blood levels evaluation should be performed annually.

Long-Term Results of Delta Ceramic-on-Ceramic Total Hip Arthroplasty

Background

Ceramic-on-ceramic (COC) bearings in total hip arthroplasty (THA) have long been considered the coupling with the lowest overall wear. However, concerns about complications such as ceramic breakage and noise, combined with the improved performance of polyethylene, have limited its use in the United States. This postapproval follow-up reports long-term (10 years) results of Delta COC in THA patients primarily enrolled in an Investigational Device Exemption study.

Methods

Patients received Delta COC THA in a prospective multicenter study with either 28-mm (N = 105 hips in 104 patients) or 36-mm (N = 81) articulations. Annual clinical and radiographic evaluations were performed for years 5 to 10, and study patients were asked about hip noises and reproducibility.

Results

There have been 4 additional reports of noise in 4 patients (COC 28, n = 3; COC 36, n = 1). The cumulative incidence rate for squeaking or noise at 10 years is 5.9% for COC 28 and 13.5% for COC 36. There have been 2 additional reports of dislocation in 2 patients (COC 28, n = 1; COC 36, n = 1). The cumulative incidence rate for dislocation at 10 years is 3.7% for COC 28 and 3.5% for COC 36. At 10 years, there were greater than 40 hips available for follow-up. At mean 10-year follow-up, there were a total of 3 ceramic liner fractures, but none since the previous report. There were no revisions in the 28-mm cohort, and 2 revisions in the 36-mm cohort (1 for recurrent dislocation and 1 for pain and noise). Overall Kaplan-Meier survivorship was 95.96% at 10.5 years (28 mm: 97.68% at 10.2 years; 36 mm: 94.11% at 10.4 years.)

Conclusions

At 10-year follow-up, we report excellent results in regard to survivorship, with one patient revised for pain with associated squeaking.

Surgeons’ Awareness and Impaction Technique of a Ceramic Liner into a Metal Shell

Background

In ceramic-on-ceramic total hip arthroplasty, firm locking is necessary between a ceramic liner and an acetabular metal shell to prevent dissociation of the liner from the metal shell. We evaluated surgeons’ awareness of the technique for inserting the ceramic liner and measured the impaction force applied by surgeons during the insertion of the ceramic liner.

Methods

To evaluate the awareness, we conducted a survey using a questionnaire including techniques for ceramic liner insertion. The impaction force was measured using an impaction simulator in 224 surgeons.

Results

Most surgeons answered that they cleaned and dried up the inner surface of the metal shell before inserting a ceramic liner (96.4% and 86.2%, respectively), and 74.6% checked the correct seating of the ceramic liner. However, only 23.2% correctly answered that a minimum of 2kN (a light strike) was necessary to obtain a sufficient fit between the metal shell and the ceramic liner. The impaction force was weaker than 2 kN in 9.4% of the surgeons.

Conclusions

Education about the adequate impaction force to obtain a firm fit of the ceramic liner is necessary for surgeons who perform total hip arthroplasty using ceramic-on-ceramic bearings.

Updates in biomaterials of bearing surfaces in total hip arthroplasty

Total hip arthroplasty (THA) is one of the most successful surgical procedures. It entails replacement of the damaged or diseased joint surface with artificial materials. Various materials had been developed and used to achieve optimal outcomes, including longer survivorship and minimal complications. The primary materials used in the manufacture of THA implants are polymers, metal alloys, and ceramics. The failures of THA mainly result from aseptic loosening due to the production of wear particles and the development of periprosthetic joint injection. A lot of advancement and introduction of new biomaterials in THA implants’ armamentarium are designed to avoid the common failure mechanisms and improve the longevity of the implants. In this review, we discussed various aspects of commonly used biomaterials in THA implants, to provide some updated information.

Catastrophic intraoperative failure of a ceramic femoral head

Approximately 17 years after a primary metal-on-metal total hip arthroplasty, a 59-year-old female developed pain, swelling, and weakness in her right hip accompanied by laboratory findings and imaging suggestive of an adverse local tissue reaction. Acetabular revision was performed to upsize the femoral head and improve hip stability. Upon impaction of the new, non-option ceramic femoral head onto the unsleeved retained stem, the head split into two pieces without fragmentation. The surgery was completed using a cobalt-chromium head, which was impacted without issue onto the stem’s taper. Although BIOLOX delta femoral heads do not require titanium sleeves, we believe that careful consideration should be given to their use in revision total hip arthroplasty with ceramic heads, regardless of the extent of trunnion damage noted intraoperatively.

Intraoperative Fracture of a Dual Modular Delta Ceramic Femoral Head During Total Hip Arthroplasty: A Case Report

CASE

A 39-year-old man with cerebral palsy and hip dysplasia status post right Chiari osteotomy presented with right hip osteoarthritis in consultation for total hip arthroplasty (THA). During THA, a Delta ceramic head was misaligned on the taper, but this was obscured by an overlying dual modular polyethylene shell. When we attempted to tap the head onto the taper, fracture occurred requiring revision to a cobalt-chromium head due to slight taper damage.

CONCLUSION

To our knowledge, this is the first reported case of intraoperative fracture of a BIOLOX Delta dual modular head.

Nano/micro implant debris affect osteogenesis by chondrocytes: Comparison between ceramic and UHMWPE from hip walking simulator

A new generation of ceramic on ceramic (BIOLOX ®delta) bearings has emerged more than 10 years ago proving a high resistance to wear and good clinical results. However, biological reactions to wear debris, particularly the nanoparticles, need to be evaluated. The first originality of this study is to start from real wear particles obtained by the hip walking simulator (CERsim). These particles were compared with particles obtained by usual methods to assess the biocompatibility of materials: press machine (CERpress). Two ranges of ceramic particles were thus observed: ceramic particles with micron (intergranular fractures) and nano sizes (intragranular fractures), and characterized compared to ultra-high molecular weight polyethylene (UHMWPE). The second originality of this work is to assess the cellular reaction using the primary joint chondrocyte cultures simulating the osteogenesis process and not the cell lines, which are used to simulate the biological reaction of osteolysis. The first results showed a significant difference in cell viability between the cells in contact with particles from the walking simulator and those obtained with the press machine. On the other hand, it was found that the way of extraction of the particles from the lubricant could significantly affect the biological reaction. More interestingly, nano-sized ceramic particles showed a significant impact on the secretion of functional inflammatory mediators, agreeing with recent results in vivo. These novel methods of characterizing the osteogenic impact of UHMWPE and ceramic wear debris can complement the conventional expertise method focusing previously on the osteolysis aspect.

Cementless ceramic-on-ceramic total hip arthroplasty in post-traumatic osteoarthritis after acetabular fracture: long-term results

INTRODUCTION

Total hip arthroplasty (THA) is the standard procedure for post-traumatic osteoarthritis (OA) of the hip after acetabular fracture. However, it is not as simple as a primary THA, challenging the surgeon with anatomical deformity and intra and postoperative complications. In the current literature, there is a lack of studies reporting long-term results. May ceramic-on-ceramic (CoC) bearings provide good clinical and radiological outcomes at a long-term follow-up in patients undergoing THA following acetabular fracture?

MATERIALS AND METHODS

We retrospectively analyzed 68 patients (mean age 47 years [range 22-75)] who underwent cementless modular neck stem THA, all implants CoC bearings (50 previously operatively treated and 18 non-operatively treated) after a specific CT study protocol at our Institute since 2000-2008. Clinical outcomes, prosthetic components' osseointegration, survival rate, and reasons for revision were analyzed. Minimum clinical and radiological follow-up was 10 years.

RESULTS

HHS improved significantly after surgery from 37.6 ± 14.1 to 88.4 ± 11.6. 8 revision surgeries were performed, none for infection: we reported 2 stem aseptic loosening, 2 periprosthetic femoral fractures and 4 modular neck fractures. One implant noise (third-generation ceramic coupling) was described. Cup osseointegration was present (according to Moore the presence of at least 3 radiological criteria defines an effective osseointegration) in 67 patients (98.5%). After a 10 years follow-up, survival rate resulted 88.4%, sensibly higher than most of results reported in the current literature.

CONCLUSION

The high survival rate may be related to CoC: no osteolysis and no infections were reported. Also acetabular cup loosening incidence was sensibly lower (1.47%) among loosening rate described by other authors. Clinical and radiological outcomes were decent, probably due to modular prosthesis design. Modular necks are a solution which can help achieving a proper functional reconstruction of the hip (offset, center of rotation), but should be avoided in young and overweight patients because of the high risk of fracture. CoC bearings in THAs in post-traumatic OA after acetabular fracture showed good results despite the fact that specific ceramic-related issues have to be considered.

The reasons for ceramic-on-ceramic revisions between the third- and fourth-generation bearings in total hip arthroplasty from multicentric registry data

This study aimed to evaluate (1) the overall reasons for first revision in CoC THAs; (2) whether the reasons for revision differ between third-generation and fourth-generation CoC THAs; and (3) the specific factors associated with bearing-related problems as the reason for revision. We retrospectively reviewed 2045 patients (2194 hips) who underwent first revision THA between 2004 and 2013, among which 146 hips with CoC bearings underwent revision. There were 92 hips with third-generation ceramic bearings and 54 hips with fourth-generation ceramic bearings. The major reasons for CoC THA revisions were ceramic fracture and loosening of the cup or stem. When ceramic fracture, squeaking, incorrect ceramic insertion, and unexplained pain were defined as directly related or potentially related to ceramic use, 28.8% (42/146) of CoC revisions were associated with bearing-related problems. Among the third-generation ceramic bearings, revision was performed in 41.3% (38/92) of cases owing to bearing-related problems whereas revisions were performed for only 7.4% (4/54) of cases with fourth-generation ceramic bearings owing to bearing-related problems (p < 0.001). Younger age, lower American Society of Anesthesiologists (ASA) grade, and preoperative diagnosis of osteonecrosis were factors related to CoC THA revisions due to bearing-related problems.

Pushing Ceramic-on-Ceramic in the most extreme wear conditions: A hip simulator study

BACKGROUND

Hip revision surgery for fractured ceramic components may represent the worst-case wear scenario due to the high risks of recurrent dislocations, instability, and third body wear. The ideal bearing choice for the new prosthetic articulation is still subject of debate, while alumina matrix composite (AMC) articulations offer theoretical superior performances; the present work was designed to test the wear behaviour of ceramic on ceramic articulations (liner and head) in a worst-case scenario by adding ceramic third-body particles to the test lubricant with combined walking and subluxation cycles in a hip joint simulator. Therefore, we performed an in vitro study aiming to assess how does AMC articulation perform with 1) third-body particles added to the test environment and 2) under subluxation stresses.

HYPOTHESIS

We hypothesised that AMC articulations offer superior performances in such worst conditions.

MATERIALS AND METHODS

A hip simulator test was designed to analyse how AMC articulation performs with third-body particles added to the test environment and under subluxation stresses. Two different load patterns including level walking and subluxation of the ceramic liner were applied. The test fluid lubricant was contaminated by adding coarse ceramic particles during the first 2 million cycles and fine ceramic particles from 2 to 4 million cycles. Group 1 consisted of an alumina matrix composite articulation (liner and head); group 2 consisted of an alumina liner and an alumina matrix composite head. A control group consisting of an alumina ceramic liner articulated against an alumina matrix composite head was provided and only axially loaded. The liners of groups 1 and 2 were tested at an in vivo angle of 45° in the medial lateral plane (inclinationangle), which corresponds to an angle L=30° relative to the ISO standard fixated position used for in vitro testing. All mass measurements were performed using a high precision balance (Sartorius BP211D). During each examination, images on dedicated location of the bearing surfaces were taken using a digital microscope.

RESULTS

Mean cumulative wear of 0.09mg per million cycles between 2 and 4 million cycles was detected in group 2, and this value was significantly lower (p=0.016) in comparison with the average value in group 1 (0.21mg per million cycle). This result can be explained in light of a possible transformation phase of zirconia in AMC liners, probably due to excessive stress during subluxation cycles. However, wear levels observed are close to the gravimetric measurement detection limit of the Sartorious Balance (about 0.1-0.2mg); therefore, wear can be considered negligible in all groups.

CONCLUSION

Our results confirm that AMC couplings perform very well even in the worst-case wear scenario. Since AMC articulations revealed 25% lower cumulative wear respect to AMC on cross linked polyethylene in same simulator setup, AMC articulations should be considered the bearing of choice in revision surgery in light of the high risk of recurrent dislocations, instability, and third body wear.

LEVEL OF EVIDENCE

III, prospective case-control study, in vitro.

Histochemical identification of wear debris released by alumina-on-alumina hip prostheses in the periprosthetic tissues

BACKGROUND

Tribological studies have shown that the most used couples for hip prostheses consist of metal-on-polyethylene and alumina-on-alumina prostheses. Over time, wear products accumulate in the joint cavity and in the periprosthetic tissues. Although polyethylene and metal are easily identifiable by microscopy in periprosthetic tissues, alumina particles are very difficult to identify.

HYPOTHESIS

The fluorescent azo-dye lumogallion was evaluated as a suitable histochemical stain for alumina particles in periprosthetic tissues.

MATERIAL AND METHOD

In 28 patients who had a prosthetic revision of an alumina-on-alumina prosthesis, periprosthetic tissues were removed and embedded in paraffin; sections were stained with HPS (for conventional diagnosis) or with lumogallion. Sections were examined for wear particles in light and fluorescence microscopy. Some sections were counter-stained using DAPI for visualization of cell nuclei.

RESULTS

The wear particles of the alumina-alumina prostheses were very difficult to identify on the HPS stained sections; they were clearly evidenced by lumogallion staining with a bright orange fluorescence. The stain revealed large quantities of particles (of the order of several thousand per section). Only two patients had no particles. The staining technique identified numerous particles that were not visible on HPS-stained sections in macrophages, synoviocytes and fibroblasts.

CONCLUSION

This staining, which has been validated in neuromuscular pathology for the identification of alumina used as a vaccine adjuvant, gave successful results in the present study. Alumina particles are modified when they are phagocytized by macrophages. lumogallion staining easily shows the presence of thousands of wear particles released by alumina-on-alumina prostheses in periprosthetic tissues.

LEVEL OF EVIDENCE

V expert opinion study.

Ceramic-on-ceramic cementless total hip arthroplasty in patients aged 40 years or under: Do preoperative conditions affect long-term results?

INTRODUCTION

Underlying diseases, bone deformities and polyethylene wear affect outcome in young patients undergoing total hip arthroplasty (THA). These issues are not widely confirmed for ceramic - on-ceramic THA, particularly regarding cup fixation. Therefore, we did a retrospective long-term investigation on a large population of cementless ceramic-on-ceramic THA in patients aged 40 years or younger aiming to analyze: 1) the complication rate; 2) clinical results; and 3) survival for cup loosening with regard to their preoperative conditions.

HYPOTHESIS

Cup loosening could be related to preoperative diagnosis in young patients with a cementless ceramic-on-ceramic THA.

PATIENTS AND METHODS

Two hundred and seven hips in 171 patients (97 men and 74 women) underwent a cementless ceramic-on-ceramic THA at a mean age of 31.6±6.8 years. The most frequent diagnoses were avascular necrosis (AVN) of the femoral head (74 hips), pediatric hip diseases (35 hips), severe congenital hip dysplasia (CHD) (31 hips), juvenile rheumatoid arthritis (30 hips) and mild CHD (26 hips). The prosthesis included a press-fit metal backed cup with a hydroxyapatite coating and a macrotexture surface on either the equatorial region (93 cups) or the entire surface of the shell (114 cups). Ceramics were made of pure alumina and had a femoral head size of 28 (60 hips) or 32mm (147 hips). In all cases same the straight cementless tapered stem was inserted.

RESULTS

There were three early dislocations, one requiring cup revision No hip was revised due to infection, ceramic fracture, or femoral component loosening. Eight cups were revised for aseptic loosening (3,8%). The mean preoperative Harris Hip score was 52.8±6.2 and 93.4±6.9 at the end of follow-up. It was better in AVN (95.7±2.3) and worst in severe CHD (88.8±11.8) (p=0.001). If the end-point was cup aseptic loosening, the survival rate at 17 years was 95.1% (95% CI: 91.3-98.9), 100% for AVN and post-traumatic arthritis, and 86.8% (95% CI: 74.9-98.7) for severe CHD.

CONCLUSIONS

Despite diagnoses frequently causing technical difficulties at the surgery, outcome of cementless ceramic-on-ceramic THA in patients under the age of 40 years is satisfactory over ten years of follow up. Cup aseptic loosening was the main cause of failure and appears more related to the initial hip diseases than the age of the patient.

LEVEL OF EVIDENCE

III; retrospective comparative study.

Impingement Between the Metal Stem and the Ceramic Liner in Total Hip Arthroplasty: The Neck Is Not the Only Place Where Impingement Occurs

BACKGROUND

It is assumed that impingement between the ceramic liner and the stem increases the possibility of a liner fracture in total hip arthroplasty with a ceramic-on-ceramic bearing. The purpose of this study was to analyze the pattern of the impingement by evaluating the notches (U-shaped indented wear scars engraved on the stem) on radiographs to determine when and where impingement develops and to analyze the factors affecting its occurrence.

METHODS

Among the primary total hip arthroplasty cases using a ceramic-on-ceramic bearing performed from November 1997 to December 2003, 244 cases of 197 patients (123 male patients and 74 female patients) that had follow-up of ≥15 years were included. All of the radiographs were examined with special regard to the notches and the cup positions.

RESULTS

Notches were detected at 77 sites of 57 cases (23.4%) for the first time between 8 months and 14.8 years after the surgical procedure. They were located on the neck or the shoulder of the stem. Shoulder notches were detected only in the cases with a short-neck head. Shoulder notches were found in 29 cases (20.0% of short-neck cases). Cup inclination was lower (p = 0.01) and anteversion was higher (p = 0.01) in the group with notches than the group without notches. There were 5 cases of ceramic head fracture. One of them experienced another ceramic liner fracture, assumed to be caused by prosthetic shoulder impingement, after the revision surgical procedure.

CONCLUSIONS

The results of this study suggest that impingement between the stem and the ceramic liner occurs in a considerable proportion of patients who underwent total hip arthroplasty not only on the neck but also on the shoulder of the stem. Forceful and abrupt impingement on the stem shoulder can cause ceramic liner fracture. Impingement between the stem shoulder and the ceramic liner should be considered in designing a stem. It seems to be prudent to recommend that patients avoid squatting or sitting cross-legged on the floor as much as possible.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Ceramic Liner Fracture Caused by an Impingement between the Stem Shoulder and the Ceramic Liner

Mechanisms of ceramic liner fractures have not yet been fully elucidated. Impingement between a stem and ceramic liner is a proposed cause of ceramic liner fractures. We experienced a case of ceramic liner fracture caused by direct impingement between the stem shoulder and the ceramic liner. This type of impingement, unlike impingements with a stem neck, has not been previously reported. While we assume that certain characteristics of the stem contributed to the impingement, we report this case to note that caution may be needed when using certain stem designs.

Outcome of Ceramic-on-Ceramic Total Hip Arthroplasty with 4th Generation 36 mm Head Compared to that with 3rd Generation 28 mm Head by Propensity Score Matching

BACKGROUND

With the development of 4th generation ceramic bearing, the large ceramic head is available for ceramic-on-ceramic total hip arthroplasty (THA). This retrospective study aimed to compare the outcomes of ceramic-on-ceramic THA with 4th generation 36 mm head to those with 3rd generation 28 mm head using propensity score matching.

METHODS

We retrospectively reviewed the results of 133 ceramic-on-ceramic THAs with 4th generation 36 mm ceramic head in 129 patients and 133 ceramic-on-ceramic THAs identified from 405 ceramic-on-ceramic THAs with 3rd generation 28 mm head by propensity score matching. There were 83 males and 50 females in both groups with a mean age of 55 years. There was no significant difference in other demographic features except for follow-up period (4.2 years in the 36 mm group and 6.4 years in the 28 mm group, p < 0.001). Clinical and radiological results and occurrence of complication were compared between the two groups.

RESULTS

Harris Hip Score was increased significantly from 46.4 to 92.1 in the 36 mm group and from 46.7 to 93.6 in the 28 mm group. No loosening or osteolysis was observed in the 36 mm group. However, one hip showed radiologic sign of loosening in the 28 mm group. As for complication, postoperative dislocation was more frequent in the 28 mm group (6 in the 28 mm group vs. 0 in the 36 mm group, p = 0.03). Otherwise, there was no significant difference in other results including inguinal pain, squeaking or ceramic fracture.

CONCLUSION

Ceramic-on-ceramic THA with 4th generation 36 mm head significantly reduced postoperative dislocation rate without increasing the rate of inguinal pain, squeaking, or ceramic fracture compared to that with 3rd generation 28 mm head.

What Is the Frequency of Fracture of Ceramic Components in THA? Results from the Norwegian Arthroplasty Register from 1997 to 2017

BACKGROUND

Ceramic bearings in THA have been used to reduce wear and, more recently, to avoid metals in the bearing because of the risk of metal ions adverse effects. Potential disadvantages to ceramic bearings are their brittleness and the ceramic fracture risk, which may lead to revision surgery. The frequency of revision for a fracture ceramic bearing, however, has not been thoroughly studied.

QUESTIONS/PURPOSES

(1) What is the frequency of revision for a fractured ceramic bearing in ceramic-on-polyethylene (CoP) and ceramic-on-ceramic (CoC) THAs, and is there any difference between alumina ceramics and alumina matrix composites (AMC)? (2) What are the factors associated with this complication? (3) To what extent did the patients who underwent revision for a fractured ceramic bearing undergo subsequent revisions, and for what reason?

METHODS

The Norwegian Arthroplasty Register has collected data on hip arthroplasty since 1987 and has a completeness of reporting of 97.3% for primary THAs and 93.3% for revision. From 1997 to 2017, 146,171 primary THAs were registered in the Norwegian Arthroplasty Register. Of these, 31,479 had a CoP articulation and 5790 had a CoC articulation. Two manufacturers produced ceramic heads; one produced 25,678 alumina heads and the other made 2465 alumina heads. All 7901 AMC heads were made by the same manufacturer. Patients who underwent CoP THA were a median (range) of 63 years old (11 to 98) and CoC THA were a median (range) 61 years old (17 to 95); 38% (11,833 of 31,479) of the patients who underwent CoP THA and 41% (2379 of 5790) of the patients who underwent CoC THA were males. Femoral heads made of alumina (n = 28,143), zirconia (n = 1225), and AMC (n = 7901) ceramics were used. To assess revision frequency, we identified patients who underwent revision because of fracture of a ceramic head and/or liner, and calculated the Kaplan-Meier survivorship free of revision for fracture in CoC and CoP articulations. Alumina ceramics and AMC were compared. In terms of factors potentially associated with revision, patient factors (age, sex, and diagnosis), type of articulation (CoP or CoC), femoral head size, and femoral head/neck length were evaluated with Cox regression models to evaluate any association with ceramic fracture and a Poisson regression to compare alumina and AMC head fractures. To evaluate subsequent revisions, hips that were revised for ceramic fracture were evaluated for any further revisions; Kaplan-Meier survivorship free of further revisions was calculated, and revision causes were identified.

RESULTS

Survivorship free from revision for ceramic fracture was 99.9% (95% CI 99.9 to 99.9) for CoP bearings, and 99.8% (95% CI 99.6 to 100) for CoC bearings at 10 years, with 7467 and 1884 hips at risk in the two groups, respectively. The hazard ratio for ceramic head fracture was 3.6 (95% CI 1.7 to 7.6) for CoC compared with CoP. The risk of fracture was greater for alumina ceramics than for AMC heads (adjusted HR 14.1 [95% CI 4.2 to 47.0]; p < 0.001). Factors that were associated with revision for fracture of a ceramic head were male sex (HR 5.2 [95% CI 2.6 to 10.4]; p < 0.001), a CoC articulation compared with CoP (HR 3.6 [95% CI 1.7 to 7.6]; p = 0.001), a 28-mm femoral head compared with a 32-mm head (HR 2.7 [95% CI 1.1 to 6.4]; p = 0.02), and short head/neck length compared with a medium head/neck length (HR 2.5 [95% CI 1.1 to 5.3]; p = 0.03). Five of 50 patients undergoing revision for ceramic fracture underwent further revisions, resulting in a 5-year survivorship free from re-revision of 86% (95% CI 74.4 to 98.0). The reasons for re-revision were infection (n = 2), another ceramic head fracture (n = 2), and cup loosening (n = 1).

CONCLUSIONS

Fracture of a ceramic THA bearing is rare and seems to affect about one in 1000 patients who receive such a bearing. To minimize the risk of this complication, surgeons should avoid small femoral heads (< 32 mm) and the shortest head/neck lengths. Surgeons should also know that the risk is increased in CoC articulations and in males. Bearings made of AMC appear to be at lower risk than those made from alumina ceramics. However, the long-term clinical wear performance of AMC bearings has not been extensively studied and should be studied further.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Incidence of Ceramic Fracture in Contemporary Ceramic-on-Ceramic Total Hip Arthroplasty: A Meta-analysis of Proportions

BACKGROUND

We performed a proportion meta-analysis of currently available data to determine the prevalence of ceramic fracture for each generation.

METHODS

A total of 10,571 total hip arthroplasties from 45 studies were included. Proportion meta-analysis with a random-effects model was performed to estimate the prevalence of ceramic fracture. To determine whether the ceramic fractures have a fatigue nature and a risk or latent period for the development, postoperative time lapse, patient age, and body mass index were related with ceramic fracture by metaregression analysis.

RESULTS

As of postoperative 2.0 to 18.8 years, the rate of ceramic fracture was 0.5% (95% CI, 0.3%-0.8%) in the forte group and 0.2% (95% CI, 0.1%-0.4%) in the delta group (P = .059). The ceramic fracture rate for each component was 0.2% (95% CI, 0.1%-0.3%) for the forte head, 0.1% (95% CI, 0.0%-0.2%) for the delta head (P = .210), 0.2% (95% CI, 0.1%-0.3%) for the forte liner, and 0.2% (95% CI, 0.1%-0.4%) for the delta liner (P = .305). The rate of ceramic fracture per 1000 patient-years was 0.9 (95% CI, 0.5-0.13) in the forte group and 0.5 (95% CI, 0.2-0.8) in the delta group (P = .072). In metaregression analysis, no significant associations were found between prevalence of ceramic fracture and postoperative time lapse, patient age, or body mass index.

CONCLUSIONS

The rate of ceramic fracture was 0.9/1000 patient-year in the forte group and 0.5/1000 patient-year in the delta group. The results of this study provide baseline data for further studies validating ceramic bearings.

LEVEL OF EVIDENCE

Level I, meta-analysis.

Ceramic on ceramic total hip arthroplasty and liner fracture. Two case reports and review of literature

BACKGROUND AND AIM OF THE WORK

Ceramic on ceramic bearing surfaces in total hip arthroplasty are rising in number with the purpose of reducing debris osteolysis in young patients. New generation ceramics drastically reduced the well known problem of liner's fracture associated with this material but this still represents a complication.

METHODS

We present the only two cases of acetabular liner fracture we had in our department, on a total of 252 patients, since we use CoC bearing surfaces in THR (2005-2019) analyzing symptoms and causes of this complication. Review of recent literature focused on symptoms and causes of liners fracture, well matched our cases.

RESULTS

In line with the analysis of literature, the major cause of liner fracture is neck-cup impingement resulting in the "edge-loading" effect, followed by other factors like prosthesis design, traumas and patient weight. From data also emerge the role of acoustic phenomena (e.g. squeaking) and CT scan in the diagnostic process.

CONCLUSIONS

Last generation ceramics should be used in CoC THR, implant malposition and prosthesis design have a dominant role in liner fracture, squeaking should always be investigated. CT scan have an important role in diagnosis. Implant revision with substitution of the bearing surfaces is mandatory in case of fracture or impending fracture signs.

Comparison of ceramic-on-ceramic bearing vs ceramic-on-highly cross-linked polyethylene-bearing surfaces in total hip arthroplasty for avascular necrosis of femoral head: a prospective cohort study with a mid-term follow-up

Background

The ideal bearing surface for patients of avascular necrosis (AVN) undergoing total hip arthroplasty (THA) remains controversial. The purpose of this study is to evaluate the clinical outcomes, health-related quality of life (HRQL), and wear of the bearing surface between ceramic-on-ceramic (CoC) and ceramic-on-highly cross-linked polyethylene (CoXPE) THA for patients of AVN after midterm follow-up.

Methods

We performed a retrospective case-control analysis of 93 CoC and 77 CoXPE consecutive THAs for patients of AVN. The cases were followed at a minimum 5 years follow-up (average 7 years). Harris hip score (HHS) score and bearing-related complications were assessed. The health-related quality of life (HRQL) was assessed with the Short Form 36 (SF-36). Plain radiographs and computed tomography (CT) were used for radiographic evaluation.

Results

Both the CoC group and CoXPE group showed statistically significant improvements in HHS scores with no difference between the two bearing surfaces. There was no significant difference as for SF-36 at the latest follow-up between two groups, except for significant higher scores in the dimensions of general health in the CoC group (75.7 vs 64.7, P = 0.032). No radiographic evidence of osteolysis and loosening was present at the final follow-up. The mean wear rate of the CoC was 0.0096 mm/year and the CoXPE was 0.047 mm/year after evaluation with reconstructed CT.

Conclusions

CoC THAs acts as well as CoXPE THAs for patients with femoral head avascular necrosis after midterm follow-up. CoC bearing can significantly decrease the wearing rate than CoXPE bearing.

Midterm outcome of fourth-generation ceramic-on-ceramic bearing surfaces in revision total hip arthroplasty

PURPOSE

The purpose of this study is to evaluate the clinical and radiologic outcomes after revision total hip arthroplasty (THA) using fourth-generation ceramic-on-ceramic (CoC) bearing surfaces.

METHODS

A total of 52 revision THAs (28 men and 19 women) using the fourth-generation CoC bearing surfaces were retrospectively evaluated. Both acetabular cup and femoral stem were revised in all cases. The mean follow-up period was 7.3 years (range, 4.0-9.9 years). The clinical results with Harris hip score (HHS), Western Ontario McMaster Osteoarthritis Index (WOMAC), and radiologic outcomes were evaluated.

RESULTS

At the final follow-up examination, the average HHS was 90.4 (range, 67-100). The average WOMAC pain and physical function score were 2.8 (range, 0-12) and 16.4 (range, 0-42), respectively. Complications were observed in 10 hips (19.2%). However, there were no bearing surface-related complications, and no cases of dislocation and squeaking. Retroacetabular pelvic osteolysis without cup loosening was observed in one hip at the final follow-up. However, no hip showed radiographic signs of cup loosening, vertical or horizontal acetabular cup migrations, and changes of inclinations during the follow-up period.

CONCLUSION

Our data showed that clinical and radiologic outcomes after revision THA using fourth-generation CoC bearing were favorable. Hence, revision THA with the use of CoC bearing surfaces can be preferentially considered. Further studies with long-term follow-up data are warranted.

A focused update on preventing ceramic fractures in hip arthroplasty

Ceramic bearings have several desirable properties, such as resistance to wear, hardness, and biocompatibility, that favour it as an articulating surface in hip arthroplasty. However, ceramic fracture remains a concern. We have reviewed the contemporary literature, addressing the factors that can influence the incidence of ceramic bearing surface fracture.

Cite this article: Bone Joint J 2019;101-B:897–901.

Heart transplant secondary to cobalt toxicity after hip arthroplasty revision

INTRODUCTION

Cobalt toxicity in patients with hip arthroplasty is a rare complication, but it should be considered in those patients who, after a ceramic fracture, were implanted with a metal-on-polyethylene prosthesis. The complete removal of ceramic particles during revision surgery can be complicated. If the bearing surface is replaced with a metal-on-polyethylene prosthesis, these residual ceramic particles may wear down the chrome-cobalt head, producing localised metallosis. This can trigger blood metal ion levels to rise, causing systemic toxicity. Visual and auditory alterations, cognitive deterioration, hypothyroidism, neuropathy, cardiomyopathy, anorexia, fatigue, diabetes, polycythemia, and respiratory and cutaneous symptoms are some of the clinical manifestations of prosthetic cobaltism.

CASE DESCRIPTION

A young patient presented with multiorgan failure secondary to cobalt toxicity after a ceramic fracture and revision with a metal-on-polyethylene prosthesis; his serum cobalt and chromium levels were 652 μg/L and 270 μg/L, respectively. The patient needed a heart transplant after presenting with cobalt-induced cardiogenic shock.

CONCLUSIONS

In a patient with a ceramic fracture who is subjected to revision surgery with a metal-on-polyethylene bearing, it is necessary to rule out the possibility of cobalt intoxication. Serum cobalt levels > 20 μg/L are inadmissible; in these cases, surgical treatment should be considered in the short term. A wide synovectomy and replacement of components should be performed with hard friction options, preferably with a ceramic-on-ceramic prosthesis.

Fourth-generation ceramic-on-ceramic THA results in improvements in midterm outcomes compared to third-generation THA but does not resolve noise problems: a cohort study of a single-hip system

BACKGROUND

Using data from the Korean Hip Registry, we aimed to investigate mid-term clinical and radiographic outcomes, including the prevalence of periprosthetic joint infection (PJI), osteolysis, and component loosening or dislocation, and to analyze the incidence of bearing-related complications following modern ceramic-on-ceramic (COC) total hip arthroplasty (THA) using a single cementless hip system.

METHODS

Four hundred eighty-two patients (602 hips) who underwent Forte or Delta COC THAs with a single hip system and had a minimum 5-year follow-up were identified. The sample included 243 (50.4%) women and 239 (49.6%) men with a mean age of 50.6 years (range: 18-83 years). The Forte group comprised 310 hips, and the Delta group comprised 292 hips. The mean follow-up was 6.1 years (range: 5-10.2 years).

RESULTS

Cup orientation did not differ between groups. No hip had a PJI or osteolysis in either group. All acetabular components and all but two femoral components (in the Delta group) were well fixed. Dislocations occurred in six (1.9%) hips in the Forte group and one (0.3%) hip in the Delta group (p = 0.124). A total of nine (1.5%) revisions were performed. The 5-year survival rates for all-cause revisions were 98.4 and 98.6%, respectively. One (0.3%) ceramic head fracture occurred in the Forte group. Sixteen (5%) hips exhibited clicking and 6 (2%) hips had squeaking in the Forte group; 16 (6%) hips exhibited clicking and 5 (2%) hips had squeaking in the Delta group. Multiple regression analysis revealed that noise generation was unassociated with any factor.

CONCLUSIONS

From the Korean Hip Registry data, THA with modern ceramic bearings showed encouraging results, with lower risks of PJI, osteolysis, and component loosening. In particular, Delta COC THA resulted in no PJI or ceramic fracture and had a reduced dislocation risk. However, associated noise remains a concern.

What factors predict ceramic liner malseating after ceramic-on-ceramic total hip arthroplasty?

BACKGROUND

There is a lack of evidence about the risk factors associated with the malseating of the acetabular liner after ceramic-on-ceramic (CoC) total hip arthroplasty (THA). Therefore, we performed a complementary retrospective case-control study to determine the factors predicting the malseating of the acetabular liner after CoC THA and to evaluate the relationship between malseating and (1) osteoarthritis, (2) particularly in terms of the new radiographic parameter "bone sclerotic length" of the acetabular bone.

HYPOTHESIS

Osteoarthritis, particularly bone sclerotic length, was an independent risk factor for malseating of ceramic liners.

PATIENTS AND METHODS

In total, 219 CoC THAs (174 women and 45 men) were evaluated to determine the risk factors influencing the malseating of the acetabular ceramic liner. An average patient age at the time of surgery was 55.9±9.5 years (range, 23 to 75 years). Data on patient background and preoperative radiographs, such as Tönnis grades; Crowe classification; and indices of acetabular osteoarthritis change; including bone cyst, osteophyte and bone sclerosis, were assessed. The bone sclerotic length in patients with osteoarthritis was measured as the slant distance between the bilateral edges of the sclerosis lesion of the acetabulum on the anteroposterior view.

RESULTS

Preoperative less hip flexion (hazard ratio [HR]: 0.98; 95% CI: 0.97-0.99), osteoarthritis (HR: 3.15; 95% CI: 1.02-9.70) and the bone sclerotic length (HR: 1.83; 95% CI: 1.35-2.48) were independent risk factors determining the malseating of ceramic liners. Receiver operating characteristic curve analysis showed that a bone sclerotic length of 24.6mm was defined as the cut-off point for the malseating of the ceramic liner.

DISCUSSION

Age, preoperative less flextion, osteoarthritis, and the bone sclerotic were independent risk factors determining malseating of ceramic liners. The acetabular shell can also deform upon insertion of the cup with sclerotic bone of the acetabulum and prevent correct seating of liners. Therefore, these factors must be taken into consideration when seating the ceramic liner.

LEVEL OF EVIDENCE

Case control study III, case control retrospective design.

Chromium-Cobalt Intoxication with Intense Systemic Complications following Total Hip Revision after Per-Operative Ceramic Fracture

Introduction

Heavy metal intoxication after arthroplasty is extremely rare but could be lethal. Case Report. We report the case of a 69-year-old woman, who presented intense systemic symptoms of chromium-cobalt intoxication after revision of per-operative fractured ceramic components with metal-on-polyethylene. Systemic toxicity occurred a year after surgery and expressed brutally with mostly central neurological symptoms. Chelation associated with revision surgery allowed rapid regression of all symptoms.

Conclusion

Revision of fractured ceramic, even per-operatively, should not be done with metal-on-polyethylene components, in order to avoid potentially lethal metal intoxication.

Hydrated Phospholipid Polymer Gel-Like Layer for Increased Durability of Orthopedic Bearing Surfaces

Recently, traditional strategies for manipulating orthopedic bearing substrates have attempted to improve their wear resistance by adjusting polyethylene substrate through cross-linking and antioxidant blending. However, further research is required on the substrate, as well as the surface focused on the structure and role of articular cartilage. We therefore develop an orthopedic bearing surface comprising a nanometer-scale hydrated gel-like layer by grafting highly hydrophilic poly(2-methacryloyloxyethyl phosphorylcholine), with the aim of mimicking the lubrication mechanism of articular cartilage, and investigate its surface characteristics, bulk characteristics, and behavior under load bearing conditions upon accelerated aging. Neither the hydrophilicity nor lubricity of the gel-like surface was influenced by accelerated aging; instead, high stability was revealed, even under strong oxidation conditions. The characteristics of the hydrated gel-like surface potentiated the wear resistance of the cross-linked polyethylene liner, irrespective of accelerated aging. These results suggest that the hydrated gel-like surface enhances the longevity of cross-linked polyethylene bearings even under load-bearing conditions. Furthermore, the inflection point on the time series of wear can be a suitable indicator of the durability of the life-long protectant. In conclusion, the hydrated gel-like surface can positively increase orthopedic implant durability.

Structural, charge density and bond length variations in c-Y2O3 influenced by progressive cerium additions

Cerium occupancy induces expansion of the cubic Y₂O₃ unit cell and yields a dense microstructure alongside enhanced mechanical properties.

Midterm Results of Fourth-Generation Ceramic-On-Ceramic Total Hip Arthroplasty

PURPOSE

There are limited reports for the results of the fourth-generation ceramic-on-ceramic (CoC) articulation total hip arthroplasty (THA). And, throughout the surgical experience, we encountered some cases of liner pulling-out phenomenon after liner fixation and femoral preparation. The objective of this study was to evaluate the incidence, risk factors of delta ceramic liner or head fractures, and also the clinical and radiological results of using the fourth-generation CoC articulation in THA.

PATIENTS AND METHODS

We retrospectively reviewed 242 patients (263 hips) who underwent primary THA using the fourth-generation CoC articulation with a minimum followup of 2 years. Demographic data, Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Patient's satisfactory level were recorded. The radiological evaluation was used to evaluate the implant fixation and complications. Mean followup duration was 5.2 years.

RESULTS

Mean HHS and WOMAC score were significantly (P < 0.05) improved at the last followup. About 98.5% of the patients were satisfied with results of the surgery. All acetabular components were placed in adequate position and there was no osteolysis on acetabular or femoral components and subsidence of femoral stem. Four patients showed complications including one-liner fracture.

CONCLUSION

Our midterm study demonstrated excellent clinical and radiological results with only one ceramic liner fracture. Moreover, the results of this study indicate that one possible cause of pulling-out phenomenon is the resonance effect during implantation in Dorr type A patients with the thick cortex. If the surgeon is aware of the liner malposition throughout the operation, the fourth-generation CoC articulation THA could be an outstanding treatment.

Hip replacement

Total hip replacement is a frequently done and highly successful surgical intervention. The procedure is undertaken to relieve pain and improve function in individuals with advanced arthritis of the hip joint. Symptomatic osteoarthritis is the most common indication for surgery. In paper 1 of this Series, we focus on how patient factors should inform the surgical decision-making process. Substantial demands are placed upon modern implants, because patients expect to remain active for longer. We discuss the advances made in implant performance and the developments in perioperative practice that have reduced complications. Assessment of surgery outcomes should include patient-reported outcome measures and implant survival rates that are based on data from joint replacement registries. The high-profile failure of some widely used metal-on-metal prostheses has shown the shortcomings of the existing regulatory framework. We consider how proposed changes to the regulatory framework could influence safety.

Primary total hip arthroplasty with fourth-generation ceramic bearings: Clinical and survival results with a minimum follow-up of 5 years

OBJECTIVE

To evaluate the clinical results and survival of primary hip prosthesis with ceramic delta bearings (C-C) with a minimum follow-up of 5years.

MATERIAL AND METHOD

A total of 205 primary hip arthroplasties performed between 2008 and 2012 were studied. The clinical results, pre-surgical and at 5years of follow-up were evaluated using the Harris Hip Score (HHS), the Short Form-36 (SF-36), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the visual analogue scale (VAS). The position of the prosthetic components, periprosthetic osteolysis, loosening of the prosthetic components and ruptures of the ceramic components were studied radiologically. The adverse events related to bearings were recorded according to their diameter, paying special attention to prosthetic dislocations and the presence of noise. Survival with an endpoint of prosthetic revision for any cause was estimated using the Kaplan-Meier method.

RESULTS

Significant improvements were obtained in the HHS (88.7% of good/excellent results), SF36, WOMAC and EVA, P<.001. There were 19 adverse events related to the prosthesis (4 periprosthetic fractures, 4 dislocations, 2 superficial infections, 1 mobilization of the cup, 2 noises, 4 aseptic loosenings and 2 breaks of the prosthetic neck); 47.3% needed revision. The cumulative survival of the prostheses was 97.5% (95%CI: 96.4-98.5). No differences were found in survival, prosthetic adverse events, noise incidence or dislocations and clinical results among the different diameters used.

CONCLUSIONS

Primary hip prostheses with fourth-generation ceramic bearings showed good survival in the medium term, and good clinical results.

Do rim cracks and backside grinding affect the aging kinetics of alumina-matrix composite acetabular liners?

The acetabular liner malalignment and rim impingement have been problematic issues in ceramic-on-ceramic (CoC) total hip arthroplasty (THA). Commercial ceramic liners made of alumina-matrix composite (AMC) have polished articulation and rim, and roughly ground backside with a button-like apical projection (post) to resist tilting. In this study, we hypothesized that rim cracks and backside grind critically affect the aging kinetics of tetragonal zirconia dispersed in AMC structure. We analyzed phase transformation in the zirconia phase and residual stresses in the alumina matrix during aging by Raman and fluorescence spectroscopy. We demonstrated that the polished surfaces showed environmental stability in vitro, while the roughly-ground backside showed a significant stability loss and tensile stress accumulation as a consequence of enhancing the inter-component fixation between the liner and the metallic shell. Rim cracking locally produced a preferential transformation at the tip and the surrounding of the crack. Note that the tensile stress concentration at the crack tip was counteracted by the phase transformation after a few hours of aging. This suggests the presence of a time lag in vivo before further transformation around the crack could provide a crack shielding effect in the material. © 2018 Wiley Periodicals, Inc. J. Biomed. Mater. Res. Part B, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 791-798, 2019.

The Ideal Total Hip Replacement Bearing Surface in the Young Patient: A Prospective Randomized Trial Comparing Alumina Ceramic-On-Ceramic With Ceramic-On-Conventional Polyethylene: 15-Year Follow-Up

BACKGROUND

The optimum bearing surface for total hip arthroplasty remains debatable. We have previously published our outcome at 10 years and this represents the 15-year follow-up.

METHODS

A total of 58 hips (in 57 patients with a mean age of 42 years) were randomized to receive either ceramic-on-ceramic (CoC) or ceramic-on-polyethylene (CoP) total hip arthroplasty. We prospectively followed for survivorship, functional outcomes (using the Harris Hip Score and the St Michael's Hip Score [SMH]), and radiological outcomes.

RESULTS

At a minimum of 15 years, 3 patients had died, but not been revised. Seven were lost to follow-up. Five cases from the CoP group were revised (4 for polyethylene wear and osteolysis). Four from the CoC were revised; one each for head fracture, instability, infection, and trunnionosis. Both groups showed statistically significant improvements in Harris Hip Score scores and SMH functional scores, with no difference between the 2 bearings. For the CoP group, there was an improvement from 15.6 to 21.5 in the SMH and from 48.8 to 88.7 (P > .05); and for CoC, this improvement was 15.8 to 23.5 and 50.3 to 94.6 (P > .05), respectively. Mean wear rate of the polyethylene was 0.092 mm/y and for the CoC was 0.018 mm/y. Two patients in the CoC group had evidence of acetabular osteolysis vs 3 in the CoP. Six patients had femoral osteolysis in the CoC group and 12 in the CoP group.

CONCLUSION

Survivorship and function of the 2 bearing groups remains comparable; while the polyethylene wear and osteolysis may represent issues in the future.