Search Results (60)

Background/Objectives: Additive manufacturing (AM) enables the production of cementless acetabular cups with porous surfaces that facilitate early osseointegration. Directed energy deposition (DED), a form of AM, allows the direct welding of porous structures onto metal substrates without requiring a vacuum environment, offering advantages over conventional powder bed fusion methods. Despite growing interest in DED, no prospective clinical studies evaluating DED-based acetabular components have been published to date. This study assessed short-term outcomes of a DED-based 3D-printed acetabular cup in total hip arthroplasty (THA). Methods: A total of 120 patients who underwent primary cementless THA using the Corentec Mirabo Z^® acetabular cup were prospectively enrolled. Among them, 124 hips from 100 patients who had completed a minimum of 24 months of follow-up were included in the analysis. Clinical outcomes were assessed using the Harris hip score (HHS), WOMAC, EQ-5D-5L, and pain NRS. Radiographic evaluation included measurements of cup position, osseointegration, and detection of interfacial or polar gaps on CT and plain radiographs. Implant-related complications were also recorded. Results: At a mean follow-up of 34.6 months, the implant survival rate was 99.3%, with one revision due to suspected osseointegration failure. The HHS improved from 56.6 to 91.4 at 24 months, and the NRS decreased from 6.2 to 1.1 (both p < 0.001). Interfacial gaps were observed in 58.1% of cases on CT, though most were <1 mm and not clinically significant. Common postoperative issues included greater trochanteric pain syndrome, squeaking, and iliotibial band tightness, all of which were resolved with conservative treatment. Conclusions: DED-based 3D-printed acetabular cups demonstrated favorable short-term clinical and radiographic outcomes, with high survivorship and reliable early osseointegration in cementless THA. Full article

Background: Total hip arthroplasty (THA) remains the standard treatment for advanced osteoarthritis, including for complex deformities. Innovations such as spherical screw-in acetabular components aim to enhance fixation and long-term outcomes. This study evaluated the long-term clinical and radiographic outcomes of cementless THA using such implants. Methods: A retrospective analysis was conducted on 277 patients (293 hips) who underwent THA with a screw-in acetabular cup (Aesculap/BBraun SC, Tuttlingen, Germany) and Antega femoral stem between 2005 and 2024. Patients were evaluated using the modified Merle d’Aubigné and Postel (MAP) score, Visual Analog Scale (VAS), and radiographic classifications, with implant survival assessed via Kaplan–Meier analysis. Results: The mean follow-up was 13.8 years. At the final follow-up, 58.7% of hips achieved excellent MAP scores, and mean VAS pain scores improved from 7.1 to 1.8 (p < 0.05). Implant positioning was within the Lewinnek safe zone in 77.1% of cases. Revision was required in 6.1% of hips, mostly due to aseptic loosening. The five- and ten-year survival rates were 98.3% and 94.0%, respectively. Conclusions: Spherical screw-in acetabular cups provide durable fixation and satisfactory long-term outcomes in THA, particularly for dysplastic hips, supporting their continued use with careful surgical techniques. Full article

Background: Stress shielding (SS) after total hip arthroplasty (THA) leads to proximal femoral bone loss and increases the risk of complications such as implant loosening and periprosthetic fracture. While various low-stiffness stems have been developed to prevent SS, they often compromise mechanical stability. A novel femoral stem composed of Ti-33.6Nb-4Sn (TNS) alloy offers a gradually decreasing Young’s modulus from proximal to distal regions, potentially improving load distribution and reducing SS. This study aimed to evaluate the mid-term clinical and radiographic outcomes of the TNS stem, with a particular focus on its effectiveness in suppressing SS. Methods: A prospective clinical study was conducted involving 35 patients who underwent THA using the TNS stem, with a minimum follow-up of 7 years. Twenty-one patients with Ti6Al4V metaphyseal-filling stems served as controls. Clinical outcomes were assessed using Japanese Orthopaedic Association (JOA) scores, and radiographic SS was graded using Engh’s classification and analyzed in Gruen zones. Inter-examiner reliability and statistical comparisons between groups were performed using appropriate tests. Results: The TNS group showed significantly higher preoperative JOA scores than the control group, but no significant difference in final scores. Both groups demonstrated significant improvement postoperatively. Third-degree SS occurred in the TNS group, although the overall SS grade distribution was significantly lower than in the control group (p = 0.03). SS frequency was significantly reduced in Gruen Zones 2, 3, and 6 in the TNS group. Conclusions: The TNS stem demonstrated a significant reduction in SS progression compared to conventional titanium stems over a 7-year period, with comparable clinical outcomes. However, the occurrence of third-degree SS indicates that material optimization alone may be insufficient, highlighting the need for further design improvements. Full article

Stress shielding remains a major concern in cementless total hip arthroplasty (THA) due to the stiffness mismatch between femoral stems and surrounding bone. This study investigated the biomechanical and clinical performance of a novel Ti-33.6Nb-4Sn (Ti-Nb-Sn) alloy stem with a graded Young’s modulus achieved through localized heat treatment. A finite element model (FEM) of the Ti-Nb-Sn stem, incorporating experimentally validated Young’s modulus gradients, was constructed and implanted into a patient-specific femoral model. Stress distribution and micromotion were assessed under physiological loading conditions. Clinical validation was performed by evaluating radiographic outcomes at 1 and 3 years postoperatively in 40 patients who underwent THA using the Ti-Nb-Sn stem. FEM analysis showed low micromotion at the proximal press-fit region (4.89 μm rotational and 11.74 μm longitudinal), well below the threshold for osseointegration and loosening. Stress distribution was concentrated in the proximal region, effectively reducing stress shielding distally. Clinical results demonstrated minimal stress shielding, with no cases exceeding Grade 3 according to Engh’s classification. The Ti-Nb-Sn stem with a gradient Young’s modulus provided biomechanical behavior closely resembling in vivo conditions and showed promising clinical results in minimizing stress shielding. These findings support the clinical potential of modulus-graded Ti-Nb-Sn stems for improving implant stability in THA. Full article

Background: The use of tapered monobloc stems in revision total hip arthroplasty (RTHA) has shown excellent results, with low implant-dependent failures due to aseptic loosening. Infection is one of the main failure reasons, but further problems, like periprosthetic fractures (PPFs), may endanger the function and duration of the implant in the long run. Methods: A consecutive series of 121 cases after femoral RTHA with a monobloc device was retrospectively investigated, and a Kaplan–Meier analysis was performed. The mean follow-up was 13.0 (range: 0.8–23.8) years. Results: PPF occurred in six patients during follow-up. The cumulative risk for PPF was 5.2% (95% CI: 1.1–9.4%) after 23.8 years. Female gender was associated with a significantly higher risk compared to male gender (9.1% (95% CI: 2.1–16.1%) after 23.1 years vs. 0% after 23.8 years; log-rank p = 0.0034). Patients operated with stems with a length equal to or longer than the calculated median length were also at a significantly higher risk of PPF during follow-up (10.2% (95% CI: 2.4–17.9%) after 23.8 years vs. 0% after 23.1 years; log-rank p = 0.0158). Diabetes at the time of index operation also significantly influenced the occurrence of a PPF during follow-up (n = 4 patients with PPF out of 107 without (4.0% (95% CI: 0.2–7.8%) after 23.8 years vs. n = 2 out of 14 with diabetes (15.4% (95% CI: 0–35.0%) after 21.1 years; log-rank p = 0.0368). The failure rate with implant removal as an endpoint due to aseptic loosening was 0%, and with infection it was 3.4% (95% CI: 0.1–6.7%), after 23.8 years. Conclusions: Although no removal of the implant due to a PPF was necessary, the cumulative risk for PPF after femoral revision with a tapered and fluted monobloc stem was higher in this long-term follow-up series compared to implant failure due to infection or aseptic loosening. Female gender and diabetes was associated with a significantly higher risk of PPF during follow-up. The use of longer stems than necessary is not preventive of PPF, and should be avoided. Full article

Background: Although tapered and fluted stems are frequently used in revision total hip arthroplasty (RTHA), major complications following the implantation of these implants, like periprosthetic fractures, are less investigated. As epidemiological data do not exist yet, the incidence of PPF in a mid- to long-term follow-up is unknown and potential risk factors have not been detected. Methods: Propensity score matching (PSA) of two retrospectively investigated cohorts after femoral RTHA with either modular (n = 130) or monobloc prosthesis (n = 129) was executed. A total of 186 cases, including 93 of each device, were finally analyzed during a mean follow-up period of 9.1 (0.5–23.1) years. The time-dependent risk of PPF was calculated using a Kaplan–Meier analysis. Results: The cumulative risk for PPF of the whole cohort was 5.7% (95% CI: 1.7–9.8%) at 23.1 years, for the modular device, 13.0% (95% CI: 0–26.0%) after 13.7 years and the monobloc stem, 3.4% (95% CI: 0–7.1%) after 23.1 years, without a significant difference between the two designs (log-rank p = 0.1922). All eight fractures occurred in women and there was one collapse of the fracture after open reduction and internal fixation. The cumulative risk was 10.1% (95% CI: 3.1–17.1%) at 23.1 years compared to 0% after 21.4 years in men (log-rank p = 0.0117). Diabetes was significantly associated with the presence of PPF during follow-up (non-diabetic, 4.4% (95% CI: 0–8.2%) after 21.3 years vs. diabetic, 16.6% (96% CI: 0–34.5%) after 13.3 years; log-rank p = 0.0066). Longer reconstructions showed also a significantly higher fracture risk (equal or longer than median implant length vs. shorter; 10.5% (95% CI: 3.1–17.1%) after 21.4 years vs. 1.0% (95% CI: 0–3.1%) after 23.1 years; log-rank p = 0.0276) but did not correlate with a preoperative defect situation. Conclusions: The cumulative risk for PPF after femoral revision with tapered and fluted devices is a relevant failure reason in this mid- to long-term investigation. There was no difference between the monobloc stem or modular implant. Women and diabetics are at risk, and the choice of a longer implant than necessary is neither prophylactical for PPF nor useful in the case of the operative treatment of a PPF after femoral RTHA with these revision devices. Full article

Background/Objectives: Stress concentration around distal screw-removal holes confers a major risk for periprosthetic fractures following conversion total hip arthroplasty (cTHA) for intertrochanteric femoral fractures. Optimal stem-selection criteria and guidelines for cTHA can improve clinical outcomes. We determined the influence of the cementless stem length on the stress distribution around distal screw-removal holes. Methods: For the finite element analysis, institutional data from preoperative CT scans of contralateral femurs of patients who underwent THA were used. To replicate the post-nail-removal state, we used 3D registration of standard triangulated language data of the intramedullary nail as an unused material to simulate distal screw-removal holes, located 135 mm from the proximal end of the intramedullary nail. Cementless stems of 130, 140, 150, and 160 mm were individually registered using STL data, and cTHA models were constructed accordingly. Using simulations under load conditions representing normal walking and stair climbing, the mean and maximum equivalent stress values around the distal screw-removal holes were calculated. For multiple comparisons, repeated-measures ANOVA with Bonferroni correction was employed. Results: Compared to the 130 mm stem, the 150 mm and 160 mm stems similarly reduced the maximum equivalent stress around the distal screw-removal holes, although the 140 mm stem showed no significant difference with other stems. Conclusions: A ≥150 mm stem length reliably mitigated stress concentration around distal screw-removal holes post-cTHA; it is the optimal choice for balancing effectiveness and risk of complications and may contribute to improved long-term clinical outcomes. This study provides practical evidence for stem selection in cTHA and offers valuable insights for future treatment guidelines. Full article

Background: Total hip arthroplasty (THA) is a widely used surgical intervention for hip osteoarthritis (HOA), with a rising demand driven by an aging population. Osteoporosis is associated with increased risks of bone loss and implant loosening after THA. While medications such as bisphosphonates and denosumab have shown promise in mitigating these risks, the impact of preoperative osteoporosis treatment on postoperative outcomes remains unclear. This study investigates the effect of preoperative osteoporosis treatment intervention on stress shielding and clinical outcomes in THA patients. Methods: This retrospective study included 107 patients who underwent cementless THA between April 2019 and March 2022. Patients under 60 years old, with a follow-up period of less than one year, or with prior hip surgery were excluded. Participants were divided into two groups: a treatment group receiving osteoporosis medication preoperatively and a non-treatment group. The outcomes assessed included preoperative bone metabolism markers, Bombelli classification, stress shielding grade, and clinical scores. Statistical analysis was performed using the Mann–Whitney U test and Chi-squared test, with significance set at p < 0.05. Results: The preoperative osteoporosis treatment intervention rate was 28.9%. Stress shielding grades were significantly lower in the treatment group (p = 0.001). However, no significant differences were observed in clinical scores one year postoperatively. Conclusion: Preoperative osteoporosis treatment significantly reduced stress shielding incidence, potentially influencing long-term outcomes by preventing bone atrophy-related pain and fractures. Preoperative bone density assessment and osteoporosis treatment intervention are recommended to improve THA outcomes. Larger studies are needed for further validation. Full article

The prototype of a biomimetic multi-spiked connecting scaffold (MSC-Scaffold) represents an essential innovation in the fixation in subchondral trabecular bone of components for a new generation of entirely cementless hip resurfacing arthroplasty (RA) endoprostheses. In designing such a functional biomaterial scaffold, identifying the microstructural and mechanical properties of the host bone compromised by degenerative disease is crucial for proper post-operative functioning and long-term maintenance of the endoprosthesis components. This study aimed to explore, depending on the occurrence of obesity, changes in the microstructure and mechanical properties of the subchondral trabecular bone in femoral heads of osteoarthritis (OA) patients caused by the MSC-Scaffold embedding. Computed microtomography (micro-CT) scanning of femoral heads from OA patients was conducted before and after the mechanical embedding of the MSC-Scaffold. Bone morphometric parameters such as bone volume/total volume (BV/TV), trabecular thickness (Tb.Th), and trabecular number (Tb.N) for regions surrounding the MSC-Scaffold were computed, and the mechanical properties such as bone density (ρ_B), bone compressive strength (S), and the Young’s modulus (E) within these regions were calculated. A statistically significant increase in BV/TV (by 15.0% and 24.9%) and Tb.Th (by 13.1% and 42.5%) and a decrease in Tb.N (by 15.2% and 23.6%) were observed, which translates to an increase in ρ_B (by 15.0% and 24.9%), S (by 28.8% and 49.5%), and E (by 18.0% and 29.8%) in non-obese patients and obese patients, respectively. These changes in properties are favorable for the mechanical loads’ transfer from the artificial joint surface via the MSC-Scaffold to the periarticular trabecular bone of the OA femoral head in the postoperative period. Full article

Background: Short-stem total hip arthroplasty (THA) has gained popularity due to its bone-sparing technique, but its outcomes in patients with obesity remain uncertain. The aim of this study was to investigate the impact of obesity on postoperative subsidence and clinical outcomes after short-stem THA. Methods: A retrospective cohort study with a minimum follow-up of 24 months was conducted on 163 patients who underwent short-stem THA with a collarless, triple-tapered, cementless stem achieving fixation in the metaphyseal region. Patients were categorized into obesity (Body Mass Index, BMI ≥ 30 kg/m²) and nonobesity (BMI < 30 kg/m²) groups. Subsidence rates, clinical outcomes, and complications were analyzed to assess the influence of BMI on the outcome of short stem THA. Regression analysis was performed to assess the influence of the independent variables (BMI, stem size, deviation from planning) on subsidence. Results: The obesity group (mean follow-up 58.6 months) exhibited significantly greater subsidence rates than did the nonobesity group (mean follow-up 38.9 months; 2.6 mm vs. 2.2 mm, p = 0.015). After removal of outliers, regression analysis revealed no linear relationship between BMI and subsidence (p = 0.35), but planned stem size was significantly correlated with subsidence (p = 0.005). Moreover, patients with obesity and larger planned stem sizes experienced greater subsidence. Clinical outcomes improved significantly in both groups. Conclusions: Obesity is associated with increased subsidence in short-stem THA, particularly in patients with larger planned stem sizes. Although BMI alone may not predict subsidence, careful selection of stem size and precise imaging techniques are crucial for minimizing subsidence risk in patients with obesity. Full article

Introduction: The use of cementation in total hip arthroplasty (THA) has evolved over the years, with a notable shift toward cementless and hybrid techniques. The aim of this study is to evaluate data from an Italian registry on the type of fixation used in THA implants and their corresponding survival rates in a large patient cohort with long-term follow-up, and to compare these data with the most recent literature. Methods: From January 2000 to December 2020, a total of 137,256 primary THA procedures were performed, of which 10.4% were fixed with stem cementation. There were 4857 revision implants, of which 11.4% were implanted with stem cementation. Results: The trend showing a significant shift toward cementless fixation methods is particularly pronounced in younger patients, with cementless implants comprising 99.5% of procedures in patients under 40 years of age. As patient age increases, the use of cemented or hybrid fixation methods becomes more common. This trend aligns with existing literature, in which cementation is often preferred for elderly patients due to concerns about bone quality and the potential for better immediate fixation provided by cemented stems. At 10 years, the implant that showed the highest survival rate was the fully cemented implant, with a rate of 94.8%. This study also reports the causes of failure based on the different fixation techniques. Conclusions: The development of standardized guidelines that consider patient-specific factors such as age, bone quality, and comorbidities in the choice of fixation type could help reduce variability in practice and improve overall outcomes in hip arthroplasty. Full article

Background: Total hip arthroplasty (THA) is a well-established and effective treatment for advanced osteoarthritis (OA) of the hip joint. While commonly performed in older patients, THA is increasingly used in younger individuals, especially in cases of secondary coxarthrosis. Technological advances have led to the development of specialized implants, which allow surgeons to address severe post-inflammatory or dysplastic deformities. Younger patients undergoing THA, often in their 20s or 30s, present higher functional expectations. Despite limited long-term studies, research indicates a higher rate of revision surgeries in this age group compared to older populations, making these procedures a unique challenge. Methods: This retrospective study analyzed 5263 primary total hip arthroplasties (THAs) performed at our center between May 1985 and December 2016. After excluding cemented and hybrid implants, as well as patients lost to follow-up or with other etiologies, 101 uncemented THA procedures in 92 patients aged 30 years or younger were included. The majority (64.4%) were due to dysplastic coxarthrosis (DDH), while avascular necrosis (26.7%) and juvenile rheumatoid arthritis (8.9%) accounted for the rest. The average patient age was 25.6 years, with a mean follow-up period of over 24 years. Surgical technique involved the anterolateral approach, with implants placed in the true acetabular region. Implants included Munich/Plasmacup, Mittelmeier, and P-M designs. Implant survival was estimated using the Kaplan–Meier estimator to determine the probability of implant longevity over the follow-up period. Outcomes were assessed using Merle d’Aubigné and Postel scores, modified by Charnley, alongside radiographic evaluations based on the Crowe, De Lee, and Gruen classifications. Results: Preoperatively radiological assessment of all hips was classified as grade IV according to the Kellgren–Lawrence scale. Over an average follow-up of 24 years, final outcomes using the modified Merle d’Aubigné and Postel (MAP) classification were excellent in 24%, good in 37%, satisfactory in 8%, and poor in 32% of cases. Results compared between DDH group and control group indicate significantly more poor results for the DDH group compared to the control group (p-value < 0.05). All poor outcomes were associated with prosthesis loosening, primarily involving P-M and Mittelmeier acetabular components. Complications included intraoperative fractures in five cases, peripheral nerve dysfunction in six cases, and heterotopic ossification in eight cases. Postoperative pain scores on the VAS scale improved from 6.8 to 1.7. The Kaplan–Meier estimator indicated 10-year survival rates of 85.2% for the entire prosthesis, with 69.8% survival at 15 years and 54.5% at 20 years. For each period the bio-functionality according to Kaplan–Meier estimator was in favor of the control group. Conclusions: Cementless THA in patients aged 30 or younger has demonstrated itself to be an efficacious treatment for hip osteoarthritis, yielding favorable bio-functional outcomes in both short- and long-term follow-up. Nevertheless, THA performed in the context of developmental dysplasia of the hip (DDH) carries a significantly elevated risk of postoperative complications, most notably aseptic loosening, which critically undermines implant survival rates. Given the young demographic and the anticipated prolonged functional lifespan of the prosthesis, there is an increased propensity for loosening over time, necessitating vigilant and sustained postoperative surveillance. Full article

Background: Recent advancements in hip arthroplasty aim to enhance the stability, longevity, and functionality of femoral implants. However, the distal fitting of femoral stems, often caused by metaphyseal–diaphyseal mismatch, remains a significant issue, particularly in patients with Dorr type A femora. Such mismatches can result in suboptimal implant performance, leading to potential complications. This study focuses on evaluating the anatomical compatibility of five representative single-tapered wedge mid–short stems with the mediolateral (ML) anatomy of the proximal femur in an East Asian population, where these mismatches are often more pronounced. Methods: A total of 742 patients from two hospitals, all of whom underwent unilateral primary total hip arthroplasty, were included in the study. The contralateral proximal femur was confirmed to have normal anatomy in each patient. Hip anteroposterior radiographs were used for measurements, which were standardized in conjunction with CT images. Key anatomical parameters were measured, including proximal and distal medial–lateral canal dimensions, vertical offset, and medial offset. Five femoral stem designs—Tri-lock^®, Taperloc^®, Anthology^®, Accolade II^®, and Fit^®—were evaluated. R programming was employed for a detailed fit analysis to match stem sizes with patient anatomy, categorizing the fit as proximal, simultaneous proximal–distal, or distal engagement. Results: Among the femoral stems analyzed, the Fit^® stem demonstrated the closest alignment with the regression line for ML widths in the study population (slope = 0.69; population ML slope = 0.38). This was followed by Accolade II^®, which had a slope of 0.83. In terms of offset options, the Accolade II^® offered the largest offset coverage, making it particularly suitable for this population. The fit analysis revealed that the Fit^® stem had the highest suitable fit rate (90.56%), followed by Accolade II^® (73.04%). Taperloc^®, Anthology^®, and Tri-lock^® had similar fit rates of approximately 59%. Overall, optimal results were obtained for 92.05% of the population in the automated fitting trial, regardless of the product type. Conclusions: When designing modern cementless femoral stems intended for press-fit fixation, it is crucial to account for the anatomical variations specific to the target population. In this study, Fit^® and Accolade II^® femoral components demonstrated superior compatibility with the femoral anatomy of the East Asian population, particularly in those with a higher incidence of Dorr type A femora. These stems, characterized by slimmer distal dimensions and high-offset options, appear to minimize metaphyseal–diaphyseal mismatch and associated complications. Full article

In patients with severe hip dysplasia, total hip arthroplasty (THA) using bulk bone graft (BBG) enhances anatomic cup positioning and provides early structural support. This study assesses the mid-term outcomes of THA with BBG in patients with over 50% graft bone coverage. Among 1951 patients who underwent THA between 2003 and 2007, 183 had BBG. After excluding early dropouts and infections, 151 patients remained. They were classified into uncovered (<50% coverage, 79 patients) and covered (>50% coverage, 72 patients) groups. The efficacy of cup fixation was compared between these groups. After ten years, the survival rate for not needing THA revision was 98% in the uncovered group and 100% in the covered group, while the rate for radiographic stability was 93% versus 99%, respectively. Although the cutoff value for the uncovered portion could not be clarified in this study, the mid-term results for 50% to approximately 70% uncovered were comparable to those for 50% or lesser, which have previously been expected to perform well. Recently, biomechanically advantageous bone grafting techniques have been identified, and based on the results of this study, it may be possible to expand the indications for THA with bone grafting for developmental dysplasia of the hip. Full article

Both cementless and cemented stems have exhibited favorable long-term outcomes in total hip arthroplasty. Nonetheless, in elderly patients, cemented hips offer an advantage due to their reduced risk of periprosthetic fractures. This study aimed to assess the initial outcomes of 28 patients who underwent unilateral cemented total hip arthroplasty utilizing a calcar-guided A2 stem (ARTIQO GmbH, Lüdinghausen, Germany). Various types of antibiotic-loaded bone cement were employed. During follow-up, we recorded demographic data and comorbidities and employed standardized clinical assessment tools, including the Harris Hip Score. Radiographic assessments included preoperative, postoperative, and follow-up imaging to evaluate subsidence, osteolysis, and bone resorption. The results indicated that among the 28 patients, 5 withdrew consent and 2 patients passed away from unrelated causes. Additionally, one prosthesis was explanted due to the undersizing of the cement stopper, which resulted in an inadequate cement mantle. As a result, 20 patients underwent a 1-year follow-up, revealing noteworthy enhancements in clinical scores, with no instances of radiolucent lines or osteolysis. No infections were detected. In summary, our short-term experience with this particular cemented short-stem design yielded promising results, exhibiting excellent functional outcomes, no aseptic loosening attributable to the stem, and no infections. Further clinical studies and registry data are essential to corroborate these findings. Full article