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.

Mixed ceramic combinations in primary total hip arthroplasty achieved reassuring mid-to-longterm outcomes.

INTRODUCTION: Ceramic-on-ceramic couplings demonstrated to be reliable bearings in primary total hip arthroplasty (THA), with long-term remarkable results. Like-on-like configurations were widely described. On the contrary, mixed material combinations from the same manufacturer, Delta-on-Forte or Forte-on-Delta, were poorly studied. In particular, it is unknown whether mixed ceramic combinations are more at risk of ceramic fractures. Thus, a registry study was conducted to investigate the long-term survival rates and reasons for revision of mixed ceramic combinations. A comparison with Delta-on-Delta couplings was also performed. MATERIALS AND METHODS: The regional arthroplasty registry RIPO was enquired about three cohorts of ceramic bearings (head-on-liner: Delta-on-Forte, Forte-on-Delta, Delta-on-Delta). Demographics, survival rates and reasons for revision were evaluated and compared. RESULTS: In total, 346 (1.5%) implants had a Delta-on-Forte coupling (mean follow-up: 6.4 years). In total, 1163 (5%) THAs had a Forte-on-Delta articulation (mean follow-up: 8.2 years). Delta-on-Delta surfaces were implanted in 21,874 (93.5%) hips (mean follow-up: 3.9 years). Mixed material combinations were implanted between 2003 and 2007. The survival rates of the three cohorts were similar and were higher than 95% at 10 years. In Forte-on-Delta group, four liners failed (0.3% of the implants), whereas ceramic fractures occurred in 15 cases (0.1%) in Delta-on-Delta couplings (3 heads and 12 liners). Considering ceramic fracture as endpoint, there was no significant difference between the three survival rates. CONCLUSIONS: Mixed ceramic bearing configurations from the same manufacturer in primary THA showed mid-to-longterm dependable outcomes, not inferior to the most recent like-on-like ceramic bearings. No additional risks of ceramic fractures were evident. Thus, closer follow-ups are not required.

Ischemia-Modified Albumin Expression: Is there a Difference between Male and Female Subjects?

BACKGROUND: Ischemia-modified albumin (IMA) derives from naive albumin, modified in the binding region of bivalent ions, as cobalt and iron. The cobalt, released from some types of hip prosthesis seems to be metabolized differently in males and females but the iron ion is more prevalent than cobalt and is detectable in the healthy population. Our aim was to verify if there are any gender- and age-related differences in IMA concentrations and if IMA correlates with cobalt and iron-related proteins. METHODS: IMA, albumin, iron, ferritin, transferrin, and cobalt were measured in 50 men and 50 women divided into two age/fertility-homogeneous groups. RESULTS: Men < 45-years-old showed a statistically significant lower IMA concentration than men ≥ 45 and fertile and menopausal women. Considering all the population studied, IMA does not seem to be correlated with age and is distributed differently by gender; also, Co distribution was different between males and females. CONCLUSIONS: IMA did not correlate with cobalt, iron, ferritin, and transferrin in any group, except for fertile women where IMA presented a statistically significant correlation with serum iron values. Minor expression of IMA in young males together with the results obtained on serum iron in fertile females, could explain the higher accumulation of circulating Co in women compared to men and their different cobalt metabolism.

Preoperative valgus deformity has twice the risk of failure as compared to varus deformity after total knee arthroplasty.

PURPOSE: The aim of this study was to assess whether preoperative valgus or varus deformity affected survivorship after total knee arthroplasty (TKA) and to quantify the risk factors for implant failure in a registry-based population. METHODS: The Emilia-Romagna Registry of Prosthetic Orthopedic Implants was examined regarding TKAs performed on patients with a preoperative diagnosis of valgus or varus deformity. Demographics, implant characteristic and survivorships were investigated and compared. A total of 2327 TKA procedures performed from 2000 to 2016 were included in the study. Six hundred and forty primary TKAs with a diagnosis of valgus deformity were evaluated with a median follow-up of 3.3 years; 1687 primary TKAs with a diagnosis of varus deformity were evaluated with a median follow-up of 2.5 years. RESULTS: Bi-compartmental, cemented posterior stabilised fixed-bearing implants were preferred. For both diagnoses, the implant survivorship rate was greater than 98% in the first year. However, the survival curve of the TKAs implanted for valgus deformity showed a greater slope in the first 3 years as compared to the survival curve of those implanted for varus deformity. Valgus deformity had a 2.1-fold higher risk for revision as compared with varus deformity. Infection was a major cause of implant failure in TKAs for varus deformity, 9/24 (37.5%), while its incidence was lower for valgus deformity, 1/21 (4.8%). CONCLUSIONS: Preoperative valgus alignment showed a twofold risk of failure as compared to varus alignment after TKA. This should be considered in daily practice, and surgeons are called on to pay more attention when performing TKAs on such patients. Prospective randomised controlled trials are, therefore, necessary to better understand the role of preoperative coronal knee deformity in implant failure. LEVEL OF EVIDENCE: Prognostic study, level III.

Delta-on-Delta Ceramic Bearing Surfaces in Revision Hip Arthroplasty.

BACKGROUND: Fourth-generation ceramic-on-ceramic couplings were developed to improve ceramic toughness and strength. Encouraging outcomes in primary total hip arthroplasty were reported. This coupling was proposed as an attractive option even in the case of revision procedures, particularly in younger patients with a longer life expectancy. However, the pertinent literature is scarce. Thus, a registry study was conducted to investigate the midterm survival rates and reasons for re-revision of the fourth-generation ceramic-on-ceramic bearing surfaces in revision hip arthroplasties. METHODS: A total of 327 revision implants (all the components were exchanged) with BIOLOX Delta couplings were investigated using the regional orthopedic registry RIPO. The demographics, the survival rates, and the reasons for re-revision were assessed. Revisions with bearings other than Delta were compared. RESULTS: Delta bearings achieved a survival rate of 90.5% at 7 years, with stable results. Twenty-six (8%) re-revisions occurred at a mean follow-up of 4.1 years. And 2.8% of the re-revisions were due to recurrent dislocations; 1.5% of the cases were due to cup aseptic loosening. Septic loosening occurred in 1.6% of the cases. No ceramic fractures were reported. When compared to revisions with bearings other than Delta-on-Delta, Delta coupling cohort achieved similar performances at 5 and 7 years. Lower, nonsignificant rates of aseptic and septic loosening were reported in Delta cohort. CONCLUSION: Delta-on-Delta couplings demonstrated to be reliable bearing surfaces in revision settings at a midterm follow-up. Clinical studies and longer follow-ups are required to investigate potential adverse effects, like squeaking and fractures, and confirm these preliminary findings. LEVEL OF EVIDENCE: Level III, therapeutic study.

Component positioning and ceramic damage in cementless ceramic-on-ceramic total hip arthroplasty.

BACKGROUND: In ceramic-on-ceramic (CoC) total hip arthroplasty (THA), component positioning demonstrated to influence the bearing damage: however the connection between angles and clinical outcomes at long-term follow-ups is currently lacking. Aims of this study were: the computer tomography (CT) assessment of component positioning in CoC THAs; the correlation analysis between positioning and ceramic damage; the identification of safe zones. METHODS: 91 consecutive post-operative CT scans including two types of CoC implants, with a mean follow-up of 12 ± 4.4 years, were evaluated. III generation (74.2%) and IV generation (25.8%) CoC surfaces were included. The angle measurements (cup abduction, anteversion, cup tilt, stem antetorsion, sacral slope) were automated using a CT-based software. The combined anteversion was assessed as well as the cup-neck position at -15°, 0°, 45° and 90° of flexion. Ceramic damage was diagnosed using synovial fluid analyses and radiological criteria. RESULTS: 63.7% of THAs was inside the cup abduction target 30°-45° and 68.1% was inside the cup anteversion target 5°-25°. 19 patients (20.9%) showed signs of ceramic damage. High cup abduction and high cup-neck 45° minimum angle (which stood for high abduction and extreme combined version) significantly correlated with ceramic damage. No demographical features apart III generation ceramic bearings influenced the results. No safe zones could be detected. CONCLUSIONS: In CoC THA, no safe zones can be described. However it is important to avoid cup inclination over 45° and a combination of steep cup and extreme combined version.

Highly porous titanium cup in cementless total hip arthroplasty: registry results at eight years.

PURPOSE: Highly porous cups were developed to improve osseointegration and reduce the rate of aseptic loosening. Highly porous titanium cups could mix the reliability of titanium metal with an enhanced porosity, improving the bony ingrowth. The aim of this report was to assess the survival rates and reasons for revision of a highly porous titanium cup, Fixa Ti-Por (Adler Ortho, Milan, Italy), fabricated using an additive manufacturing. METHODS: The Registry of Prosthetic Orthopedic Implants (RIPO), the Emilia-Romagna region arthroplasty registry, was enquired about cementless cups, implanted since July 2007. Ti-Por cups were compared to all the other cementless sockets, acting as a control group. The survival rates and reasons for revision were evaluated and compared. Comparisons with the same articular couplings were also provided. RESULTS: When all the articular couplings were included, Ti-Por performed better, achieving a statistically higher survival rate than the control group (98.7% vs 97.9%) and a statistically lower incidence of cup aseptic loosening. In case of ceramic on polyethylene couplings, Ti-Por achieved similar survival rate: cup aseptic loosening in Ti-Por group was 0.2%, whereas the control group rated 0.4%. In ceramic-on-ceramic implants, the survival rate was similar in the two groups, Ti-Por achieving a cup aseptic loosening rate of 0.1% (vs 0.14% in the control group). CONCLUSION: Highly porous titanium cups showed trustworthy results at eight years, reducing the rate of aseptic loosening. Longer follow-ups, ion analyses, and pre-clinical in vivo studies would be helpful to better define the reliability of these devices and their advantages.

The influence of bearing surfaces on periprosthetic hip infections: analysis of thirty nine thousand, two hundred and six cementless total hip arthroplasties.

PURPOSE: Periprosthetic hip infection (PHI) is a devastating complication. The association between PHI and bearing surfaces as well as patient-related factors has been recently investigated, with contradictive outcomes. The dataset of Emilia-Romagna region Registry for Orthopaedic Prosthetic Implants (RIPO) has been assessed to investigate, if the bearing choice influenced the risk of septic loosening occurrence. METHODS: RIPO data about 39,206 cementless total hip arthroplasties (THA), collected since 2003, were analysed. Age, gender, BMI, diabetes and bearing surfaces were evaluated. The end point of the study was the revision of at least a single component due to sepsis. RESULTS: Adjusted and unadjusted survival rates showed that ceramic-on-ceramic (COC) implants had the lower incidence of PHIs, whereas metal-on-metal (MOM) THAs were significantly more prone to infection. In MOM cohort, stemmed implants were involved in 28 out of 30 cases. Among the demographical features and comorbid conditions, only diabetes statistically influenced the rate of sepsis. CONCLUSIONS: Bearing surfaces influenced the rate of PHI; in particular, stemmed MOM implants were at higher risk, probably due to metal debris consequent to taperosis. Despite the preliminary results, stemmed MOM THAs should be used with care, and diabetic patients should be warned about increased septic risks.

Short Stems Versus Conventional Stems in Cementless Total Hip Arthroplasty: A Long-Term Registry Study.

BACKGROUND: Short stems in total hip arthroplasty (THA) have recently gained increasing popularity, allowing mini-invasive exposures and bone-sparing approaches. However, long-term studies and recommendations for the routine use are not available. The aim of this report was to compare the survival rates and the reasons for revision of short stems versus conventional stems in cementless THAs, in a registry-based population. METHODS: The Registry of Prosthetic Orthopedic Implants (RIPO) was inquired about cementless THAs performed since 2000 to 2016. The stems were divided into short (<12 cm) and conventional ones, and then, classified according to the classification by Feyen and Shimmin: short stems with neck-retaining osteotomy (group A: 1684 hips), short stems with standard osteotomy (group B: 2727 THAs), and conventional stems (group C: 57,359 cases). Demographics, survivorships, and reasons for revision were investigated and compared. RESULTS: Short stems were preferentially implanted in younger patients and normal morphologies. Short and conventional stems showed comparable survival rates at long-term follow-up (>90% at 15 years). The rates of stem aseptic loosening, intraoperative fractures, and periprosthetic fractures were similar in the 3 groups. Group B had higher rates of revisions due to primary instability (early dislocations and impingement-related events; P < .05). Revisions due to pain were nonsignificantly higher in group B. CONCLUSION: Short stems are reliable implants at long-term follow-up. The comparison with conventional stems showed no additional risk of premature aseptic loosening and intraoperative and periprosthetic fractures. However, the high rate of revisions due to pain and, mostly, primary instability should be investigated in clinical trials.

Is Cross-Linked Polyethylene an Improvement Over Conventional Ultra-High Molecular Weight Polyethylene in Total Knee Arthroplasty?

BACKGROUND: Reducing polyethylene (PE) wear by increasing the cross-linking encouraged surgeons to hope for increased total knee arthroplasty (TKA) survival rates. Different methods of manufacturing cross-linked polyethylene (XLPE) were introduced, following promising in vitro results. Is there a measurable effect of cross-linking on TKA survival? METHODS: A registry study was conducted, focusing on fixed tibial inserts in primary TKA. Conventional PE represented 87% of the liners, 10% were cross-linked and 2% were antioxidant PE. Sixty-four percent of the liners were posterior-stabilized (PS). Survival of the different PE groups and survival of the main XLPE available were successively compared. We also looked for differences in the same brand implant groups with regard to PE type, as well as differences between cruciate retaining and PS knees. RESULTS: No differences were found when looking at survival for any cause or for aseptic loosening only (P = .96). When comparing the XLPE available, X3 was found to have a better survival than Prolong or Smith & Nephew XLPE (P = .036). When the same implants and X3 or conventional PE were used, no difference could reach a statistical significance. With Zimmer LPS Flex, Prolong XLPE was even associated with a lower survival compared with conventional PE. On Stryker implants, only the Cox regression model allowed highlighting a difference between X3 XLPE and conventional PE, only in PS knees. CONCLUSION: Increasing the cross-linking seems to only have a low effect, if any, on knee arthroplasty survival. Differences between brands could be found; the manufacturing process could play a role.

Total Knee Replacement in Young Patients: Survival and Causes of Revision in a Registry Population.

BACKGROUND: The incidence of total knee replacements (TKRs) in young patients is increasing. Few reports described encouraging results and acceptable survival rates. However, many concerns still persist, in particular about the high rates of infection and aseptic loosening. Aim of this article was to investigate the survival of TKRs in patients aged 45 years or younger in a registry population. METHODS: The Emilia-Romagna registry RIPO was enquired about TKRs in patients ≤45 years; 238 TKRs were evaluated at a mean follow-up of 5.4 years (range 0-15.6 years), examining the features of the patients involved, the survival rate, and the reasons for revision of the knee implants. RESULTS: The TKRs were generally performed in men, in private hospitals, and almost in half of the cases for other causes rather than primary osteoarthritis. The mean age was 40 years. Bicompartmental, cemented posterior-stabilized implants with fixed bearing were preferred. The survival rate was higher than 90% in the first 7 years, and then it decremented. The choice of implant did not apparently influence the survivorship. The final outcomes were acceptable, substantially in line with the previous literature about young patients. Twenty-one revisions occurred (8.8%), in particular 8 cases for aseptic loosening and 7 TKRs for infection. The rate of revision was higher than in overall population and even in some young cohorts. CONCLUSION: TKRs in patients aged 45 years or younger seem a promising procedure, although the high rates of septic and aseptic loosening should be carefully evaluated. Prospective, well-designed studies are required to confirm and investigate these preliminary findings.

Metal-on-metal hip prostheses: correlation between debris in the synovial fluid and levels of cobalt and chromium ions in the bloodstream.

PURPOSE: Hip prostheses with metal-on-metal (MoM) coupling can release cobalt-chromium particles and ions. The aim of this work is to verify the correlation between particles in the synovial fluid and circulating ions. METHODS: Forty patients were enrolled; particles from synovial fluid were analysed by SEM­EDX (Scanning Electron Microscopy-Energy Dispersion X-rays analysis) and levels of circulating Co and Cr were assayed by ICP-MS (inductively-coupled plasma mass spectrometry). RESULTS: In 16 cases we did not find any particles in the synovial fluid and the Co level in whole blood was 0.05­4.42 ppb; in seven with few particles the blood level was 2.2­15.6 ppb; in six cases with several particles the level was 5.0­54.3 ppb; finally, in 11 cases we isolated not only Co-Cr particles, but also Cr particles with low or absent Co and in these patients the circulating level of Co was 23.8­109.6 ppb. Co in serumand Cr level both whole blood and serum have shown a similar trend to Co; the correlation between all these values and the corresponding particles is statistically significant in all cases. CONCLUSION: Co and Cr both in serum and whole blood represents a systemic representation of the particle release at local level and can therefore be used to confirm a diagnosis and monitor the wear process of MoM articular prostheses.

Detection of cobalt in synovial fluid from metal-on-metal hip prosthesis: correlation with the ion haematic level.

Hip replacement with large metal-on-metal (MoM) coupling has recently been under attention for its metal ions release, inducing several disorders. Since the blood level toxicity threshold for cobalt is known, the aim of this work is to determine whether Co serum and blood levels correlate with the synovial fluid level. Beside this, the synovial fluid Co from patients without prosthesis has also been measured. Co has been determined in 54 samples (32 unilateral MoM and 22 controls) with inductively coupled plasma mass spectrometry in the three matrices. In the prosthesized group, cobalt was significantly higher compared with controls and in the synovial fluid it strongly correlated with whole blood Co (p = 0.847) and serum (p = 0.855). Moreover, the Co levels into whole blood and serum were significantly different. In conclusion, haematic Co concentration correctly reflects Co local level.

Uncemented primary total hip arthroplasty, presentation of pain, and expression of osteonectin.

Osteonectin (ON) is an important matrix glycoprotein highly expressed in bone. In several in vitro and animal model studies, ON was used as indicator of the state of osseointegration of implanted devices. There are, however, no studies on ON expression in the synovial fluid of patients with total hip joint replacement (THJR). The purpose of our study was to determine the ON concentration in synovial fluid from three groups of patients: primary uncemented THJR with hip pain ("pain" group; n = 15) and without pain ("no-pain" group; n = 12), and patients with osteoarthitis scheduled to receive a primary THJR (control group; n = 5). For the prosthesized groups, the statistical nature of the correlation between ON concentration and patient age, in situ life of the THJR, presence of periprosthetic osteolysis, and presence of debris in the synovial fluid was individually investigated. ON concentration was determined using enzyme-linked immunosorbent assay, the presence of periprosthetic osteolysis was established using X-radiography and Engh's criteria, and the presence of debris was determined using digestion and EDX spectroscopy. ON concentration was significantly lower in the "pain" group compared with the "no-pain" one (median values 19.0 and 53.2 ng/mL, respectively). ON concentration in the control group (median value: 16.9 ng/mL) was comparable with that reported in the literature. In the prosthesized groups, ON concentration was not correlated with patient age, in situ life of the prosthesis, presence of periprosthetic osteolysis, or presence of debris in the synovial fluid. Our results suggest that cases of unexplained pain in THJR patients could be treated by paying special attention to the osseointegration status of the implant by using ON concentration as an early indicator of this status.

Ceramic debris in hip prosthesis: correlation between synovial fluid and joint capsule.

Detection of ceramic particles in synovial fluids allows early diagnosis of ceramic damage, but there is no evidence of a relationship between ceramic debris in the articular space and in the joint capsule. The aim of the present study is to verify if the particles isolated in the synovial fluid are comparable with those stored in the capsular tissue. Twenty-one patients were enrolled. Both synovial fluid and capsular samples were collected during revision surgery and ceramic particles were isolated and analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis. It resulted a significant correlation between the samples couples (18 out of 21). This study confirms that the synovial fluid analysis can give a clear definition of the presence of particles in the joint capsule.

Monocyte chemoattractant protein 1 expression in synovial fluid of patients with total hip arthroplasty.

Monocyte chemoattractant protein 1 (MCP-1) is a member of the chemokines family that stimulates monocyte chemotaxis and whose expression is induced during osseous inflammation. Total hip arthroplasty (THA) now uses ceramic-on-ceramic (cer-cer) or metal-on-metal (met-met) coupling that is considered the bearing of new generation, with improved performance compared with the previous polyethylene bearings. While the ceramic on ceramic is universally considered highly biocompatible, met-met coupling can induce hypersensitivity correlated to immunological response. This study aimed at quantifying the MCP-1 levels in synovial fluid of THA patients with these two articular couplings; synovial fluid of osteoarthritic patients who underwent primary THA was used as a control. The presence of wear particles originating from the prostheses was also assessed in the synovial fluid by scanning electron microscopy and energy dispersive X-ray spectroscopy. The MCP-1 levels in the synovial fluid of 17 patients with met-met coupling were significantly higher than in 13 patients with cer-cer coupling and in seven controls; median MCP-1 level was 919 pg/mL in the cer-cer group, 4274 pg/mL in the met-met group, and 326 pg/mL in the control group. No correlation was found between MCP-1 levels and the presence of wear particles in the synovial fluid, time from surgery, or periprosthetic osteolysis. We conclude that the presence of the prosthesis is responsible for an increase in the level of MCP-1; moreover, the significantly higher level of this chemokine in met-met coupling can be related to inflammatory and possibly hypersensitivity processes induced by metal ions.

Modeling the cost-effectiveness for cement-less and hybrid prosthesis in total hip replacement in Emilia Romagna, Italy.

BACKGROUND: The aim of the present study was to assess the cost-effectiveness of cement-less versus hybrid prostheses in total hip replacement (THR) in patients diagnosed with primary osteoarthritis. METHODS: Effectiveness data were obtained from the Emilia-Romagna Regional Registry on Orthopaedic Prosthesis (RIPO), which collects information on all orthopaedic intervention performed in Emilia-Romagna (41,199 total hip replacements performed from 2000 to 2007), and from which we obtained survival curves and transition probabilities for the cement-less and hybrid prostheses, respectively. Conversely, costs were derived from regional databases through a specific procedure, which allowed us to register individual component's costs for both primary and subsequent revision interventions. A specific Markov transition model was constructed in order to consider the 3 types of revisions that an implant could possibly undergo through its life-span: total, cup or stem, head insert or neck. The cost-effectiveness was expressed in terms of cost per "revision-free" life year. RESULTS AND CONCLUSIONS: Considering a 70-y old patient undergoing THR, the cementless strategy resulted more effective but more costly than the hybrid solution, with an incremental cost effectiveness ratio of 2401.63 € per revision-free life year. Following a deterministic sensitivity analysis, hybrid and cementless fixation showed, respectively, a dominance profile for patients older than 83 y and younger than 43 y, whereas for all ages in between, we report a progressive increase in the ICER of cementless prostheses. Our results proved to be robust, as underlined by the probabilistic sensitivity analysis performed using cost distributions.

A pictographic atlas for classifying damage modes on polyethylene bearings.

Evaluation of medical devices retrieved after in vivo service provides unique evidence related to the physiological environment in which the biomaterials performed. This study implements a training procedure for evaluating polyethylene bearings of joint prostheses obtained after pre-clinical tests or explanted after in vivo function. A total of 161 damage regions on 45 bearings were evaluated by four observers. An illustrated Damage Mode Atlas was developed as a reference guide, inclusive of both photographs and concise written descriptions of 16 specific damage modes that are typical for polyethylene bearings. Utilizing the Damage Mode Atlas to train new researchers improved the damage pattern analysis, including more accurate identification of damage modes and improved inter-rater reliability. This Damage Mode Atlas is a useful supplementary tool for conducting Stage II non-destructive analysis of explanted polyethylene bearings used for joint replacement, in accordance with international guidelines for evaluating explanted medical devices.

Osteon classification in human fibular shaft by circularly polarized light.

Pattern of osteonal classification referred to collagen fiber orientation in a human fibula was studied. Along the length of the whole bone, serial 100-microm parallel cross sections were obtained and analyzed by circularly polarized light microscopy. The distribution of 3 different kinds of osteons (transversal, alternated and longitudinal-hooped) depending on their collagen fiber orientation were analyzed to determine the effect of length, anatomical quadrant and cortical thickness. Referring to length, the 3 types of osteons appeared with approximately the same relative frequency, but when the symmetry of the fibula was considered and the length was expressed as distance from the bone mid-section, the alternated osteons are predominant in the mid-section. On the contrary, moving toward the epiphyses, the balance is inverted, and transversal together with longitudinal-hooped types become more frequent than the alternated type. Osteonal pattern distribution was not significantly affected by the anatomical quadrant of each section or by the thickness of the cortex. This observation seems to confirm that along the fibula shaft the orientation of collagen fibers within the osteons is consistent with the loading conditions which the bone undergoes.

Analysis of the surface topography of retrieved metal-on-polyethylene reverse shoulder prostheses.

Despite the encouraging short- and medium-term clinical results and increased usage of reverse shoulder replacements, a higher revision rate is documented compared with other major joint arthroplasties. Adverse reaction to polyethylene wear debris is still an important factor which may influence the long-term survival of reverse shoulder arthroplasty. To date, only a small number of retrieval studies of reverse shoulder arthroplasty have reported the different damage modes on polyethylene components, but none have quantified the ex vivo surface roughness on both articulating surfaces. The main purpose of this study was to assess, for the first time, the surface roughness of 13 retrieved metal-on-polyethylene reverse shoulder replacements using a white light profilometre with nanometre resolution. Although no significant relationship was observed between the surface roughness values and patient variables, it was noted that half of the polyethylene components still showed their original machining marks, indicating little change in vivo and that the metallic humeral components in the reversed design configuration showed low values of surface roughness after their time in vivo.