Titanium Cup Research Articles

Highly Porous Titanium Cups Frequently Presenting with Radiolucent Lines in Cementless Primary Total Hip Arthroplasty: A Retrospective Cohort Study.

Background/Objectives: A highly porous titanium cup with a three-dimensional metal interface was recently introduced to improve biological fixation and survival. However, radiography has revealed concerns regarding these cups, despite their excellent short- and mid-term clinical outcomes. This study compared the clinical and radiographic results of a highly porous titanium cup with those of a hydroxyapatite-coated porous titanium cup after primary total hip arthroplasty (THA). Methods: Fifty-one primary THAs were investigated. A highly porous titanium cup was used in 17 hips, and a hydroxyapatite-coated porous titanium cup was used in 34 hips. No significant differences in preoperative patient demographic characteristics were observed between the two groups. The 2-year postoperative clinical and radiographic results were compared. Results: Radiolucent lines were observed in 13 (76%) of 17 hips with highly porous titanium cups and in none (0%) of 34 hips with hydroxyapatite-coated porous titanium cups (p < 0.001). In the highly porous titanium cup group, radiolucent lines were observed in five hips (29%) in one zone, two hips (11%) in two zones, and six hips (35%) in three zones. No cup loosening was observed in either group. Conclusions: Radiolucent lines were significantly more frequent in highly porous titanium cups. This study suggests that, compared to the three-dimensional structure of porous titanium, the hydroxyapatite coating of porous titanium had a greater influence on bone ingrowth in the short term. The meaning of these findings in the long-term is unclear yet.

Enhancing Hip Arthroplasty Outcomes: The Multifaceted Advantages, Limitations, and Future Directions of 3D Printing Technology.

In the evolving field oforthopedic surgery, the integration of three-dimensional printing (3D printing) has emerged as a transformative technology, particularly in addressing the rising incidence of degenerative joint diseases. The integration of 3D printing technology in hip arthroplasty offers substantial advantages throughout the surgical process. In preoperative planning, 3D models enable meticulous assessments, aiding in accurate implant selection and precise surgical strategies. Intraoperatively, the technology contributes to precise prosthesis design, reducing operation duration, X-ray exposures, and blood loss. Beyond surgery, 3D printing revolutionizes medical equipment production, imaging, and implant design, showcasing benefits such as enhanced osseointegration and reduced stress shielding with titanium cups. Challenges include a higher risk of postoperative infection due to the porous surfaces of 3D-printed implants, technical complexities in the printing process, and the need for skilled manpower. Despite these challenges, the evolving nature of 3D printing technologies underscores the importance of relying on existing orthopedic surgical practices while emphasizing the need for standardized guidelines to fully harness its potential in improving patient care.

Usefulness of a Cementless Highly-Porous Acetabular Cup in Rheumatoid Arthritis Patients Undergoing Total Hip Arthroplasty.

Total hip arthroplasty in patients with rheumatoid arthritis is difficult and leads to worse implant survival and higher risk for complications compared to osteoarthritis. Poor periacetabular bone quality might challenge the stability of the acetabular cup. Contemporary 3D-printed highly-porous titanium cup designs have become the benchmark for cementless implants; however, their usefulness in rheumatoid arthritis is still unclear. The purpose of this study was to assess the short-term results of the use of a highly-porous 3D-printed acetabular titanium cup in patients with rheumatoid arthritis. We studied a consecutive series of RA patients who underwent cementless THA between 2019 and 2020 in our center with the same 3D-printed highly-porous titanium acetabular cup. All patients were evaluated prospectively for a minimum 3-year follow-up with the Harris hip score, VAS and Roles and Maudsley score. Radiographic assessment focused on evidence of cup osseointegration. 37 RA patients, mean age at surgery of 51.3 years, were included. Mean follow-up was 3.2 years (3 to 4 years). By the last follow-up visit, the Harris hip score had increased significantly from 37.8 to 88.5, VAS had decreased from 6.1 to 1.0 and excellent satisfaction for 31 patients. All 5 Moore's radiographic signs were present in 35 hips, with only 4 signs present in the remaining 2 hips, thus indicating complete osseointegration of all cups. There were no complications on the acetabular side but one intraoperative proximal calcar fracture. 3D-printed highly porous implants used in primary THA worked well in patients with rheumatoid arthritis, showing excellent osseointegration and good clinical results in the short term.

Short- to Mid-Term Clinical and Radiological Results of Selective Laser Melting Highly Porous Titanium Cup in Primary Total Hip Arthroplasty.

(1) Background: The aim of this study was to evaluate short- to mid-term clinical and radiological results in patients undergoing primary total hip arthroplasty (THA) with the use of a Selective Laser Melting 3D-printed highly porous titanium acetabular cup (Jump System Traser®, Permedica Orthopaedics). (2) Methods: We conducted a retrospective study and collected prospective data on 125 consecutive patients who underwent primary THA with the use of highly porous titanium cup. Each patient was evaluated preoperatively and postoperatively with a clinical and radiological assessment. (3) Results: The final cohort consisted of 104 patients evaluated after a correct value of 52 (38-74) months. The median Harris Hip Score (HHS) significantly improved from 63.7 (16-95.8) preoperatively to 94.8 (38.2-95.8) postoperatively (p < 0.001), with higher improvement associated with higher age at surgery (β = 0.22, p = 0.025). On postoperative radiographs, the average acetabular cup inclination and anteversion were 46° (30°-57°) and 15° (1°-32°), respectively. All cups radiographically showed signs of osseointegration with no radiolucency observed, or component loosening. (4) Conclusions: The use of this highly porous acetabular cup in primary THA achieved excellent clinical, functional, and radiological results at mid-term follow-up. A better clinical recovery can be expected in older patients. The radiological evaluation showed excellent osseointegration of the cup with complete absence of periprosthetic radiolucent lines.

Initial stability of cementless acetabular cups using robotic‐assisted total hip arthroplasty compared with the conventional manual technique: An in vitro biomechanical study

AbstractBackgroundThe aim of this study is to determine whether the initial stability of a cementless cup with the Mako system is superior to that of a conventional manual technique using bone models.MethodsThe bone models were prepared using a polyurethane foam block. Two hemispherical cementless cups (highly porous titanium cup [Trident II Tritanium, Stryker] and hydroxyapatite‐coated titanium cup [Trident HA, Stryker]) were implanted using the Mako system. The torque of the cups was measured by rotational and lever‐out torque testing and compared with that of a conventional manual technique.ResultsThe two types of cups that were implanted using the Mako system demonstrated significantly higher mean rotational torque than that of the manual technique (p &lt; 0.01, p = 0.01, respectively).ConclusionsThis study provides the advantage of the initial stability of a cementless hemispherical cup implanted by the Mako system compared with that of the conventional manual technique.

Trabecular titanium cups in hip revision surgery: a systematic review of the literature.

Hip revision surgery in extensive acetabular bone defects represents a complex challenge for hip surgeons. The primary goal is to obtain a stable acetabular component and restore the hip biomechanics. Through the years, different prosthetic implants have been developed to perform acetabular revision depending on bone loss location and extension. This systematic review aims to summarize the clinical outcomes and complications reported with trabecular titanium (TT) cups in hip revision surgery. A literature search of four databases (PubMed, Embase, Scopus and the Cochrane Database of systematic reviews) was performed according to the PRISMA guideline from January 2008 to December 2022. All studies written in English and reporting the clinical outcome of patients undergoing revision total hip arthroplasty using Delta TT cups were included. The initial screening identified 378 studies. Each eligible clinical article was analyzed according to the Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence (LoE), and the papers' methodological quality was evaluated using The Methodological Index for Non-Randomized Studies Criteria (MINORS) score. Eight clinical studies were included in the analysis. A total of 523 hip revisions were analyzed. Delta TT cups were used in 3.9%, Delta TT one cups in 46.8%, and Delta TT revisions in 49.3%. Paprosky IIIa was the most frequent acetabular bone defect reported in 26.4% of cases. The overall survival rate of TT cups was 93.4%. The dislocation was the most frequent complication in 4.1% of patients, while the prevalence of aseptic loosening was 1.5. Managing severe acetabular bone defects remains a complex challenge for hip surgeons. Since their introduction, TT cups have exhibited good clinical results, with complication rates in line with or lower than those reported by similar implants.

Standardized 3D-printed trabecular titanium augment and cup for acetabular bone defects in revision hip arthroplasty: a mid-term follow-up study

BackgroundThe aim of this study was to assess the feasibility and outcomes of standardized three-dimensional (3D)-printed trabecular titanium (TT) cups and augments to reconstruct most acetabular defects.MethodsWe included 58 patients with Paprosky type II and III acetabular bone defects who underwent revision hip arthroplasty between 2015 and 2018. Patients who were revised without 3D-printed augments, and cases who were lost to follow-up and died during follow-up were excluded. Radiographic and clinical outcomes were evaluated. A Kaplan–Meier survivorship curve was generated. The mean follow-up was 64.5 (range 49–84) months.ResultsIn total, 48 (82.8%) acetabular revisions were performed using standardized 3D-printed TT cups and augments, and a retrospective review was conducted on 43 revisions. The average position of the vertical center of rotation and leg length discrepancy were significantly decreased from 42.4 ± 9.1 mm and 38.4 ± 10.7 mm to 22.8 ± 3.4 mm and 4.1 ± 3.0 mm, respectively. Non-progressive radiolucent lines were observed in 3 (7.5%) acetabular components with no indications for revision. The mean Harris hip score, Oxford hip score and EuroQol five-dimensional questionnaire score increased from 33.0 ± 10.7, 11.4 ± 3.4 and 0.29 ± 0.09 to 80.3 ± 8.8, 35.8 ± 2.4 and 0.71 ± 0.10, respectively. The revision-free survival rate of the acetabular component was 93.0% (40/43), with a rate of revision for aseptic loosening of 2.3% (1/43).ConclusionStandardized 3D‑printed TT augments and cups could be used to reconstruct the majority of Paprosky type II and III acetabular defects in revision hip arthroplasty and demonstrated encouraging results at mid-term follow-up.

Five-Year Survival of the Delta One TT and Revision TT Systems after Primary Complex and Acetabular Revision Surgery

Introduction: Use of Trabecular Titanium cups in total hip arthroplasty is expected to reduce the incidence of loosening of the acetabular component of the prosthesis. We reviewed clinical outcomes of the Delta One TT and Delta Revision TT acetabular systems during five-year follow-up after primary complex or acetabular revision surgery.

Translated article] Trabecular titanium implants in complex acetabular revision surgery

IntroductionAcetabular revision surgery is a surgical challenge, especially when complex bone defects appear. This makes primary fixation and osseointegration of the implants difficult, which conditions the appearance of complications. Trabecular titanium implants attempt to solve these problems. ObjectivesTo evaluate our clinical-radiological results, the survival of the implants and the appearance of mid-term complications in acetabular revision surgery in a series of 37 acetabular replacements with Paprosky type IIIA and IIIB bone defects in which a trabecular titanium Cup-Cage revision implant was used. Material and methodWe conducted an observational, descriptive and retrospective study of 37 cases with complex acetabular defects (20 type IIIA and 17 type IIIB, five of them with pelvic discontinuity) in which the acetabular component was replaced by trabecular titanium cups between 2011 and 2019. We analysed clinical results (pain and functionality) and radiological parameters (restoration of the hip rotation centre and the mobilisation of the implants), as well as the appearance of complications. ResultsThe mean follow-up was 61 months. We obtained a median improvement of 8 points on the Merlé D’Aubigné-Postel functionality scale and 6 points on the VAS scale of pain perceived by the patient. We recorded two cases of acetabular loosening, one case of dislocation and three surgical wound infections without affecting the implant. ConclusionsThe use of trabecular titanium Cup-Cage implants could be a valid option in acetabular revision surgery with complex acetabular defects, presenting good clinical and radiological results and in terms of complications and survival of the implants, mainly due to their good primary fixation and subsequent osseointegration.

Outcomes of novel 3D-printed fully porous titanium cup and a cemented highly cross-linked polyethylene liner in complex and revision total hip arthroplasty

IntroductionA novel fully porous acetabular titanium shell has been designed to reduce stiffness mismatch between bone and implant and promote osseointegration in complex (cTHA) and revision total hip arthroplasty (rTHA). A highly cross-linked polyethylene (XLPE) liner is cemented within the cup to reduce wear rates and increase survivorship. This study reported the outcomes of an XLPE liner cemented into a novel 3D-printed fully porous cup in cTHA and rTHA.MethodsPresented was a multicenter retrospective review of 40 patients (6 cTHA and 34 rTHA) who underwent THA with a fully porous titanium acetabular cup and cemented XLPE liner. Data were collected on demographics, surgical information, outcomes, including osseointegration and migration and implant survivorship.ResultsOn average, patients were 71.42 ± 9.97 years old and obese (BMI: 30.36 ± 6.88 kg/m2) and were followed up for a mean time of 2.21 ± 0.77 years. Six patients underwent cTHA and 34 patients underwent rTHA. The mean hospital length of stay was 5.34 ± 3.34 days. Three (7.5%) 90-day readmissions were noted. Harris Hip Scores improved, on average, from 53.87 ± 12.58 preoperatively to 83.53 ± 12.15 postoperatively (P<0.001). One case of acetabular shell aspetic loosening with migration was noted. Thirty-nine of the 40 acetabular components were fully osseointegrated without migration. Two patients underwent re-revision surgery for PJI and one patient received acetabular shell+liner re-revision due to aseptic loosening. Kaplan-Meier analysis showed an all-cause revision-free survival rate of 95.0% at 6 months and 1 year, and 92.0% at 4-years. Aseptic acetabular cup, liner dislocation/loosening, and fracture-free survival was 100% at 6 months and 1-year, and 97.1% at 2 years.ConclusionThe combined use of a novel 3D-printed fully porous titanium acetabular shell and cemented XLPE acetabular liner yielded excellent rates of osseointegration, and all-cause and acetabular aseptic loosening survivorship at a minimum 1-year follow-up. Further long-term studies are needed to assess the longevity of this construct.

Clinical and radiological outcomes of total hip arthroplasty in octogenarian patients using a three-dimensional porous titanium cup: a retrospective analysis in Japanese patients.

Osteointegration of a three-dimensional (3D) porous titanium material has been experimentally proven, but only a few studies have shown the clinical outcomes of a 3D porous titanium cup in the Japanese elderly population. The purpose of this study was to compare the short-and-medium term clinical and radiographic results of total hip arthroplasty (THA) using a 3D porous titanium cup in patients aged ≥ 80 (octogenarians) versus those aged < 80 (younger controls). A total of 104 hips that underwent THA using a 3D porous titanium cup (SQRUM TT, Kyocera Medical) were enrolled in the study and were divided into two groups according to age: the octogenarian group (≥ 80, n = 42) and the younger control group (< 80, n = 62). Furthermore, we evaluated patient characteristics, clinical outcomes determined by the Japanese Orthopedic Association score, cup alignment, and incidence of radiolucent lines around the cup. The mean follow-up period was 4.2 and 4.0years (p = 0.29) for octogenarians and younger controls, respectively. The clinical outcomes were excellent, and no revision surgery occurred until the last follow-up in both groups. The number of patients with radiolucent lines at the final evaluation was 21 of 62 (33.9%) in younger controls and 16 of 42 (38.1%) in octogenarians. THA with 3D porous titanium cup for octogenarians had similar clinical outcomes and incidence of radiolucent lines as those of younger controls, suggesting that the 3D porous titanium cup may be useful in THA for octogenarians. Further investigations will confirm its long-term outcomes.

Implantes de titanio trabecular en cirugía de revisión acetabular compleja

IntroductionAcetabular revision surgery is a surgical challenge, especially when complex bone defects appear. This makes primary fixation and osseointegration of the implants difficult, which conditions the appearance of complications. Trabecular titanium implants attempt to solve these problems. ObjectivesTo evaluate our clinical-radiological results, the survival of the implants and the appearance of mid-term complications in acetabular revision surgery in a series of 37 acetabular replacements with Paprosky type IIIA and IIIB bone defects in which a trabecular titanium Cup-Cage revision implant was used. Material and methodWe conducted an observational, descriptive and retrospective study of 37 cases with complex acetabular defects (20 type IIIA and 17 type IIIB, five of them with pelvic discontinuity) in which the acetabular component was replaced by trabecular titanium cups between 2011 and 2019. We analyzed clinical results (pain and functionality) and radiological parameters (restoration of the hip rotation centre and the mobilization of the implants), as well as the appearance of complications. ResultsThe mean follow-up was 61 months. We obtained a median improvement of 8 points on the Merlé D’Aubigné-Postel functionality scale and 6 points on the VAS scale of pain perceived by the patient. We recorded two cases of acetabular loosening, one case of dislocation and three surgical wound infections without affecting the implant. ConclusionsThe use of trabecular titanium Cup-Cage implants could be a valid option in acetabular revision surgery with complex acetabular defects, presenting good clinical and radiological results and in terms of complications and survival of the implants, mainly due to their good primary fixation and subsequent osseointegration.

Comparison of early migration patterns between a ceramic and polyethylene liner in uncemented Trabecular Titanium cups: a 2-year randomized controlled trial of 52 hips using radiostereometric analysis.

Background and purposeCeramic liners may reduce early stability of uncemented acetabular components due to higher stiffness. However, the bone ingrowth capacities of porous trabecular titanium might compensate for this effect. This prospective randomized trial quantifies migration patterns of the Delta-TT cup, and compares polyethylene and ceramic liners.Patients and methodsPatients undergoing primary uncemented total hip arthroplasty with the Delta-TT cup and femoral stem with ceramic head were randomized to a polyethylene (n = 25) or ceramic (n = 28) liner. Radiostereometric analysis (RSA) radiographs, patient-reported hip function (HOOS-PS, OHS), and quality of life (EQ5D) were collected at baseline and 1.5, 3, 6, 12, and 24 months postoperatively. Model-based RSA was used to calculate 3D cup translation and rotation, and mixed models were used to compare effects over time between groups.ResultsAt 2 years follow-up, Delta-TT cups showed similar mean proximal translation of 0.56 mm (95% CI 0.38– 0.75) in the ceramic (CE) group and 0.54 mm (0.30–0.77) in the polyethylene (PE) group, with a between group effect of 0.02 mm (–0.20–0.23). Most cup migration occurred in the first 1.5 to 3 months, stabilizing within 6 months. Any between-group effects were ≤ 0.30 mm for translation and ≤ 0.45° for rotation. Improvements in patient-reported hip function and quality of life were similar in both groups.InterpretationRegardless of liner type, Delta-TT cups showed some initial migration and stabilized within 6 months, which seems promising for longterm fixation in both cup-liner constructs.

Le type de insert n’a aucun impact sur les changements de densité minérale osseuse autour d’une cupule acétabulaire en titane trabéculaire imprimée en 3D

BackgroundThree-dimensional printing of implants allows the ability to produce implants and interfaces which theoretically better mimic “normal” bone behaviour, leading to a possible reduction in stress shielding thus maintaining bone mineral density (BMD). This issue was not investigated in vivo using bone scan and different bearings, therefore we did a prospective study aiming to answer: 1) Is there a loss of BMD around the 3D printed trabecular titanium cup, when compared to the native hip? 2) Does liner type influence the BMD changes around the acetabulum when a 3D printed trabecular titanium cup is used? HypothesisBMD changes around the acetabulum are not influenced by the liner type, and the cup will be associated with a reduction in BMD when compared to the native hip. Material and methodsThis is a prospective observational study of patients receiving a primary total hip arthroplasty. A 3D printed Trabecular Titanium uncemented acetabular component was used in all cases. All patients received a ceramic femoral head, with either a ceramic or polyethylene acetabular liner. BMD measurements using DXA were performed at 6 weeks, 6,12 and 24 months after surgery to evaluate remodeling changes. The 3 acetabular regions of interest (ROI) of DeLee and Charnley were used for serial comparisons of peri-acetabular BMD. The study was powered as a non-inferiority study with the principle variables compared using a two-step repeated analysis of variance. ResultsA total of 48 consecutive patients were included in the study, with all patients completing their 2 year follow up. There were no failures, revisions or complications within this cohort. We found no statistically significant difference in the BMD change scores between the operated and the native hip in any of the 3 ROI zones. We found no differences in BMD scores when comparing ceramic to polyethylene acetabular liners, head sizes and BMI. DiscussionThis study shows a similar pattern of BMD behaviour around a 3D printed cup when compared to the contralateral native hip. We were unable to show a clinical or radiological difference between the bearing material, head size, or BMI when used with this type of acetabular component. Level of EvidenceIII; prospective comparative study.

PERIACETABULAR BONE CHANGES AFTER TOTAL HIP ARTHROPLASTY WITH HIGHLY POROUS TITANIUM CUPS IN PATIENTS WITH LOW BONE MASS.

The aim: To assess the bone remodeling around highly porous titanium cups TTM in patients with low bone mass one year after total hip arthroplasty (THA). Materials and methods: In this prospective study were included 18 patients (18 hips), whom was performed primary THA with the use of TTM cups. According to T-score of Lumbar Spine, patients were divided into 2 groups: normal bone mineral density (BMD) (n=9) if T-score ≥ -1, and low BMD (n=9) if T-score < -1. According to DeLee and Charnley's model BMD in 3 periacetabular regions were evaluated 1 week and 1 year after THA. Results: One year after primary THA, BMD of all 3 periacetabular regions did not differ in patients of both groups comparing with initial data. One week after THA, it was found that BMD R1 and BMD R3 in low BMD group were lower by 1.4 times (p=0.035) and 1.5 times (р=0.001) respectively, BMD R2 did not differ from the normal BMD group. One year after THA it was found that in low BMD group BMD R1 and BMD R2 were lower by 1.5 times (р=0.005) and 1.3 times (р=0.050) respectively, BMD R3 did not differ from the group with normal BMD. Conclusions: The use of highly porous titanium cups TTM in patients with low bone mass did not lead to a bone loss in DeLee and Charnley periacetabular zones one year after THA. Consequently, the use of these cups in patients with low bone mass undergoing THA is a valuable treatment option.

Trabecular titanium cups in acetabular revision arthroplasty: analysis of 10-year survivorship, restoration of center of rotation and osteointegration.

In case of severe bone loss, acetabular revision can be challenged using extra porous pure trabecular titanium (TT) revision cups designed to ensure enhanced iliac and ischiatic purchase. Aim of the study is to report on the clinical and radiological results of a TT acetabular component, evaluating functional outcome, restoration of the hip center of rotation and osteointegration. 85 patients, who underwent acetabular revision with a TT revision cup system between October 2009 and December 2018, were included in a retrospective study. Clinical outcome were assessed with Harris Hip Score (HHS). The hip rotation center was measured using the Pierchon method on the AP pelvis film. Loosening of the cup was determined according to the Kosashvili modification of Gill's criteria. Kaplan- Meier survivorship curve was performed. Results The mean follow-up was 6.12years. The average HHS improved from 54.7 points to 89.7 points (p < 0.05). Two acetabular components (2.3%) were re-revised after a mean of 5.6years, for aseptic loosening and for infection, with a progressive radiolucency and a > 5mm vertical migration, respectively. The radiographic evaluation of the position of the hip rotation center revealed a statistically significant difference (p < 0.05) between the pre- and post-operative values. The hip rotation center was correctly restored within 5% of the reference Pierchon values in a percentage of 85.4% relative to horizontal parameters and within 8% in a percentage of 66.7% relative to vertical parameters. 5-year and 10-year survivorships were, respectively, 100% and 88%. In case of severe bone loss, TT revision cup system allows for good restoration of center of rotation and osteointegration showing good 10-year survival rate.

Investigation of the effect of porous titanium cups on stress distribution in bone tissue (mathematical modeling)

Introduction. During arthroplasty in patients with altered anatomy and osteoporosis of the acetabulum, stable fixation of the acetabular component of the endoprosthesis is a very difficult task. There are studies on the bone tissue bonding to titanium, tantalum and ceramic coatings of endoprostheses. However, there are insufficient data on the influence of the strength characteristics of modern surfaces of the cups for hip endoprostheses on the distribution of mechanical stresses in the bone tissue around the implanted components. The purpose was to study on a mathematical model the changes in the stress-strain state of the endoprosthesis-bone system as a result of using porous tantalum cup. Materials and methods. A mathematical modeling has been carried out of the stress-strain state of the human hip joint in arthroplasty with porous cup. Du-ring the study, a defect in the acetabular roof filled with a bone implant fixed with two screws was simulated, as well as a defect in the acetabular floor filled with bone “chips”. Endoprosthesis cups were modeled in two versions: from solid titanium with a spray coating of porous titanium, and those entirely made of porous titanium. A distributed load of 540 N was applied to the sacrum. A load was applied between the iliac wing and the greater trochanter of the femur simulating the action of the gluteus medius — 1150 N and the gluteus minimus — 50 N. Results. The use of a cup with a coating of porous titanium in the normal state of the acetabulum leads to the occurrence of maximum stresses (15.9 MPa) in its posterior-upper part. Minimum stresses of 4.6 MPa are observed in the center of the acetabulum. The use of an endoprosthesis with porous titanium cup allows reducing the level of stresses in the bone tissue around the cup. If there is a defect in the acetabular roof, a hip endoprosthesis with porous titanium cup causes less stress than a solid titanium cup with coating of porous titanium. But on the graft, the stress level remains practically unchanged, regardless of the type of cup. The use of porous tantalum cup in the presence of a defect in the acetabular floor causes significantly less stress in the bone tissue around it, compared to an all-metal cup with coating. Conclusions. The cup of the hip endoprosthesis made of porous titanium causes significantly less stress in all control points of the model, compared to a cup made of solid titanium with coating of porous titanium, both with defects in the acetabular roof and floor, and without bone defects.

Serum Metal Ions in Contemporary Monoblock and Modular Dual Mobility Articulations.

BackgroundQuestions exist about the release of cobalt and chromium ions from dual mobility (DM) cups. Modular implants, with potential backside wear between the cobalt-chromium liner and titanium cup, are of particular concern. This study compares the metal ion profile of patients with contemporary monoblock and modular DM articulations from two commonly used designs.MethodsCobalt and chromium serum levels were measured one year after surgery in a prospective cohort of patients undergoing total hip arthroplasty with a DM construct. Ion levels were detected above 1 μg/L. Clinical and surgical data were correlated with the ion levels for analysis.ResultsOverall, 29% of the patients had levels above 1 μg/L of either ion. More patients with modular cups had detectable ions than patients with monoblock cups (39% vs 20%, P = .05). Cobalt was more commonly detected in the monoblock group, and chromium was more commonly detected in the modular group (P = .05). There were no differences in the actual ion levels between the groups (1.35 μg/L vs 1.64 μg/L, P = .44, for cobalt and 1.35 μg/L vs 1.31 μg/L, P = .77, for chromium). No patient underwent revision during the follow-up period.ConclusionsWe found similar cobalt and chromium levels in patients with monoblock and modular DM cups. More patients in the modular group had detectable ions. Cobalt was more frequently detected in the monoblock group. These results suggest that both implants are performing well in the short term, but further follow-up is needed to determine whether the differences found are of clinical significance.

Liner type has no impact on bone mineral density changes around a 3D printed trabecular titanium acetabular component

BackgroundThree-dimensional printing of implants allows the ability to produce implants and interfaces which theoretically better mimic “normal” bone behaviour, leading to a possible reduction in stress shielding thus maintaining bone mineral density (BMD). This issue was not investigated in vivo using bone scan and different bearings; therefore, we did a prospective study aiming to answer: 1) is there a loss of BMD around the 3D printed trabecular titanium cup, when compared to the native hip?; 2) does liner type influence the BMD changes around the acetabulum when a 3D printed trabecular titanium cup is used? HypothesisBMD changes around the acetabulum are not influenced by the liner type, and the cup will be associated with a reduction in BMD when compared to the native hip. Material and methodsThis is a prospective observational study of patients receiving a primary total hip arthroplasty. A 3D printed trabecular titanium uncemented acetabular component was used in all cases. All patients received a ceramic femoral head, with either a ceramic or polyethylene acetabular liner. BMD measurements using DXA were performed at 6 weeks, 6, 12 and 24 months after surgery to evaluate remodeling changes. The 3 acetabular regions of interest (ROI) of DeLee and Charnley were used for serial comparisons of peri-acetabular BMD. The study was powered as a non-inferiority study with the principle variables compared using a two-step repeated analysis of variance. ResultsA total of 48 consecutive patients were included in the study, with all patients completing their 2 year follow-up. There were no failures, revisions or complications within this cohort. We found no statistically significant difference in the BMD change scores between the operated and the native hip in any of the 3 ROI zones. We found no differences in BMD scores when comparing ceramic to polyethylene acetabular liners, head sizes and BMI. DiscussionThis study shows a similar pattern of BMD behaviour around a 3D printed cup when compared to the contralateral native hip. We were unable to show a clinical or radiological difference between the bearing material, head size, or BMI when used with this type of acetabular component. Level of evidenceIII; prospective comparative study.

High Risk of Neck-liner Impingement and Notching Observed with Thick Femoral Neck Implants in Ceramic-on-ceramic THA.

Recently, impingement between the femoral stem and ceramic liner, which appears as a notch in the stem neck on radiographs, has emerged as a new complication. However, the proportion of impingement, potential risk factors, and related complications are poorly elucidated. In patients who underwent ceramic-on-ceramic (CoC) THA and had at least 10 years of follow-up, we asked: (1) What proportion had radiographic evidence of stem neck-ceramic liner impingement (notching of the stem), and what implant design, implantation factors, or complications such as ceramic fracture or metallosis are associated with impingement? (2) How common are the complications of noise and ceramic fracture? (3) What are the radiologic changes (including fixation of femoral and acetabular components, osteolysis, and heterotopic ossification) and clinical outcomes as determined by the modified Harris hip score (mHHS) for this cohort? (4) What is the survivorship with implant revision as the endpoint and with reoperation for any reason as the endpoint after CoC THA using a thick-neck stem design? Between May 2003 and April 2010, 643 patients underwent primary THA at a tertiary referral hospital. After excluding patients with metal-on-polyethylene and with ceramic-on-polyethylene implants, 621 patients were considered eligible for this study. All patients received the same hemispherical titanium cup, a standard-length tapered titanium stem, and a CoC bearing. Of those, 19% (115) were lost to follow-up before 10 years, and 8% (50) were excluded because they died before the minimum follow-up duration of 10 years, leaving 73% (456) for analysis. Patients had a mean age of 50 ± 14 years and were followed for a median (range) of 13 years (10 to 17). The mean cup abduction was 38° ± 5°, and the mean cup anteversion was 26° ± 7°. To determine the proportion of patients with the neck-liner impingement, we analyzed the plain radiographs of every patient during follow-up to detect notches around the stem. The detection of stem neck notches on the radiographs was reliable (intraobserver reliability: κ = 0.963; p < 0.001 and interobserver reliability: κ = 0.975; p < 0.001). To evaluate factors related to notching, we compared the possible confounding factors including gender, age, BMI, implant position, neck length, and head diameter. Complications such as ceramic fracture, noise, dislocation, and periprosthetic joint infection were recorded. Noise was evaluated via interview and with the Hip Noise Assessment Questionnaire, which assessed the noise qualitatively. For clinical outcome, we assessed the mHHS, which includes pain and function scales (0 [worst] to 100 [best]), every visit. Tilting of at least 4° or migration of at least 4 mm was the criteria for cup loosening; subsidence more than 3 mm, any change in position, or a continuous radiolucent line greater than 2 mm was the criteria for stem loosening. To evaluate osteolysis, we performed CT scans in 57% (262 of 456) of patients. Kaplan-Meier survivorship analysis was performed using the endpoints of survivorship free from implant revision and survivorship free from reoperation for any cause. The proportion of stem neck notching was 11% (49 of 456). There were no differences in cup abduction and anteversion between hips with notches and those without notches. Notched hips were more likely to have 28-mm than 32-mm heads (90% [44 of 49] versus 70% [285 of 407]; odds ratio 3.77 [95% CI 1.46 to 9.73]; p = 0.004). None of the 49 notched hips had a ceramic head or liner fracture or evidence of metallosis. A ceramic head fracture was reported in 2% (9 of 456); all fractures occurred in 28-mm short neck heads. A ceramic liner fracture occurred in 0.2% (1 of 456), and noise was noted in 6% (27 of 456). Acetabular osteolysis developed in 2% (7 of 456). The mHHS was 91 ± 12 points at the final follow-up. The survivorship free from implant revision was 97% (95% CI 96% to 99%), and the survivorship free from reoperation for any cause was 96% (95% CI 95% to 98%) at 13 years. The proportion of stems with neck-ceramic liner impingement and ceramic component fracture were unacceptably high after the use of a thick-neck stem design, especially when a 28-mm head was used. We have discontinued the use of this stem design and we recommend that such stems should not be used when CoC bearings are used. As these findings might be generalized to other bearing couples, further studies focused on polyethylene liner wear and local metallosis due to thick stem neck are warranted. Level III, therapeutic study.