Cementless Femoral Stem Research Articles

Long-term clinical results and patient satisfaction of a metaphyseal-engaging anatomic cementless femoral component in total hip arthroplasty.

There is relatively little information on the long-term clinical results of patients aged < 50 years with a contemporary total hip arthroplasty (THA), although a high rate of revision is projected for this group. Therefore, the purpose of this study was to evaluate the long-term results (a minimum of 21 years) of a metaphyseal-engaging anatomic cementless total hip prosthesis in patients aged < 50 years at the time of their THA. This study included 360 patients (498 hips), specifically 212 men and 148 women. The mean age of the patients at the time of their THA was 45.8 ± 8.1 years. The predominant diagnosis was osteonecrosis (56%). Demographic data, the Harris hip score, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the University of California, Los Angeles (UCLA) activity score were recorded. Radiographic evaluation and dual-energy X-ray absorptiometry (DEXA) scanning were used to evaluate implant fixation, bone remodelling, and osteolysis. The mean follow-up was 25.2 year (range 21-28 years). At the latest follow-up, the mean Harris hip, WOMAC, and UCLA activity scores were 93, 10, and 6.7 points, respectively. No patients had thigh pain. All hips had osseous integration of the acetabular and femoral components. No patient had grade 3 stress shielding. The 28-year survival rate was 98.2% (95% confidence interval [CI] 95-100%) for the acetabular components and 98.8% (95% CI 95-100%) for the femoral components. Overall, 90% of the patients were satisfied with the THA results. The results suggest that a metaphyseal-engaging anatomic cementless femoral stem with alumina-on-alumina ceramic articulation provide outstanding long-term fixation and substantial pain relief well into the 3rd decade after surgery. Furthermore, there was no alumina ceramic fracture or osteolysis. Moreover, approximately 90% of the patients were satisfied with the results of their THA.

Low Rate of Early Periprosthetic Fractures in Direct Anterior Total Hip Arthroplasty with a Triple-Tapered Wedge Stem.

Utilization of the direct anterior approach (DAA) for total hip arthroplasty (THA) has been steadily increasing in recent years. While the DAA may offer some benefits compared to other approaches, there are still risks involved including relatively higher rates of periprosthetic femur fractures, especially when combined with cementless femoral stem use. The purpose of this study is to evaluate the early postoperative femoral complications with a short triple-wedge tapered stem used in primary THA via a DAA. A retrospective review was conducted of the arthroplasty registry of our institution from April 2022 to August 2023 to identify patients who underwent a primary THA via a DAA with the Short Medacta Stem (SMS) (Medacta International, Castel San Pietro, Switzerland). Patients were excluded if the stem was used for a revision surgery, they were within 90 days of surgery, or they refused research consent. Inclusion criteria was met in 262 patients (302 hips). Data was collected after reviewing the chart, and reports and radiographic measurements, including Dorr type and canal fit ratios, were obtained from preoperative and postoperative radiographs, respectively. A total of 302 total hips were included, 161 patients were male (53.3%) and 141 were female (46.7%), with an average age of 66.5 years (27-88, +/- 10.7 years). Average follow up was 0.3 years (range, 0.05-1.71 years). The majority of patients had a Dorr B femur (81.7%). The Median stem size used was an 8 (range, 2-15), and 89.4% of those had a collar. Average canal fill ratio was 0.83 (range, 0.43-0.98, +/- 0.07). Overall, there were two Vancouver B2a periprosthetic femoral shaft fractures (0.66%) that required revision surgery to a modular stem. In addition, there were two Vancouver Ag greater trochanteric fractures (0.66%) with acceptable alignment that did not require revision surgery. Demographic information about the patients with femoral complications is summarized in Table I. Average age of patients with femoral complications was 69.5 years, with an average canal fit ratio of 0.88. We found that the triple-wedge implant had a low rate of early femoral complication in primary THA from an anterior approach and is safe for use in THA from a DAA. More follow up is needed to evaluate continuing implant survivorship and patient outcomes.

Biomechanical Comparison of Impaction Techniques and Cross-Sectional Femoral Stem Shapes for Cementless Total Hip Arthroplasty.

Traditional mallet broaching and stem seating in cementless total hip arthroplasty (THA) can result in femoral stem misalignment, potentially reducing implant longevity. This study aimed to compare the pullout strength of cementless THA femoral stems with different cross-sectional designs achieved through the powered impactor method versus the traditional mallet method. The authors utilized 24 polyurethane foam femurs and two femoral bone preservation stems with different proximal cross-sectional shapes (double taper: ACTIS®, size 5; flat taper: TRI-LOCK®, size 5). A single orthopedic surgeon broached each femur from size 0 to size 5 using either the powered impactor or mallet impaction methods. Broaching time and component implantation times were recorded. A load-to-failure pullout strength test was conducted, and the ultimate pullout load was recorded. The broaching time for the TRI-LOCK® stem showed a statistically significant difference between the two impaction methods (powered: 37±7 seconds, mallet: 75±29 seconds, F[3, 20] = 4.56, p = 0.002), but no statistically significant difference was detected for the ACTIS® stem between the two impaction methods (powered: 47±22 seconds, mallet: 59±9 seconds, F[3, 20] = 4.56, p = 0.304). There was a statistically significant difference in pullout strength between the two impaction groups, and this strength was influenced by the implant cross-sectional shape (ACTIS®: 774±75N versus 679±22N, F(3,20) = 16.38, p = 0.018; TRI-LOCK®: 616±57N versus 859±85N, F(3, 20) = 16.38, p <0.001). The technique used for femoral bone preparation (powered impactor versus mallet) and the cross-sectional design of the cementless femoral stem are crucial factors that affect initial stem stability and operation time.

Finite Element Models to Predict the Risk of Aseptic Loosening in Cementless Femoral Stems: A Literature Review

Aseptic loosening is the most common failure mode for total hip arthroplasty, and the design of the implant plays a significant role in influencing the longevity and stability of the implant. Finite Element (FE) models have been demonstrated to be powerful numerical tools that allow for generating information supporting the device’s safety and/or efficacy during pre-clinical assessment. Different authors have proposed FE studies aiming to simulate the long-term stability of the femoral stem; however, multiple improvements are still necessary for translating computational methodologies into clinical practice. This paper provides a comprehensive overview of the modelling procedures for predicting aseptic loosening risk, focusing on cementless femoral stems. The main modelling assumptions, including bone and implant geometry, materials, boundary conditions, and bone–implant interface contact, were summarised and presented. The limitations of various modelling assumptions and their impact on the simulation results were also discussed. The analysis suggests that more rigorous clinical validation for osseointegration models and failure criteria used to determine loosening of the implant should be clearly defined, and efforts should be made to identify the appropriate limit of tolerable conditions.

Three-Dimensional Osseointegration Patterns of Cementless Femoral Stems: An ex Vivo Study with High-Resolution Imaging and Histological Evaluation.

Osseointegration is essential for the long-term survival of cementless femoral stems and is dependent on periprosthetic bone quality and correct implantation technique. The aim of this study was to evaluate the 3-dimensional long-term fixation patterns of, and bone microarchitecture around, cementless hip stems. Four specimens with varying degrees of bone quality and fixation characteristics from body donors who had received Alloclassic Zweymüller hip stems during their lifetime (mean time in situ at the time of death: 12.73 years) were evaluated with use of radiographs, high-resolution computed tomography (CT) scans, and hard-tissue histology. The CT voxel size was 85 µm, and the following parameters were calculated: total bone volume, total bone volume fraction, trabecular bone volume, trabecular bone volume fraction, cortical bone volume, cortical bone volume fraction, and cortical thickness. Bone-implant contact and canal fill index values for each Gruen zone of the specimens were calculated with use of histological samples. Femoral stems with apparently good cortical contact on clinical radiographs showed higher values for cortical bone volume, trabecular bone volume, and cortical thickness in the high-resolution CT analysis than femoral stems with apparently weak cortical contact on clinical radiographs. Based on the histological evaluation, the mean bone-implant contact ranged from 22.94% to 57.24% and the mean canal fill index ranged from 52.33% to 69.67% among the specimens. This study demonstrated different osseointegration patterns of cementless femoral stems on the basis of radiographs, high-resolution CT scans, and histological evaluation. Femora with high cortical bone volume and cortical thickness were associated with higher canal fill indices, whereas femora with low cortical bone volume and cortical thickness had lower canal fill indices and showed a characteristic corner-anchorage pattern. Osseointegration patterns and thus the long-term survival of cementless femoral stems are dependent on cortical bone volume and cortical thickness.

Chronological Changes in Sagittal Femoral Bowing after Primary Cementless Total Hip Arthroplasty: A Comparative 3D CT Study.

Little is known about dynamic changes of femoral anatomy after total hip arthroplasty (THA), in particular about sagittal femoral bowing (SFB). A 3D CT study was designed to evaluate the chronological changes of SFB after cementless femoral stem implantation for primary THA. Ten patients who underwent unilateral primary THA with a cementless femoral stem, with 2 consecutive CT scans (extending from the fourth lumbar vertebra to the tibial plateaus), performed before THA and at least 3 years after THA, were enrolled. The 3D models of femurs were created using image segmentation software. Using the two CT scans, SFB values of the proximal and middle thirds were calculated on the replaced and untreated sides by two different observers. Eight anatomical stems and two conical stems were involved. The post-operative CT was performed at an average follow-up of 6.5 years after THA (range: 3-12.5). The measurements performed by the two observers did not differ in the proximal and middle regions. A significant difference between the pre-operative and post-operative SFB compared to the untreated side was found in the proximal femur segment (p = 0.004). Use of a cementless stem in THA induced chronological changes in SFB of the proximal femur, after a minimum timespan of 3 years.

Osteoporotic Patients Undergoing Total Hip Arthroplasty Have a Similar 5-Year Cumulative Incidence Rate of Periprosthetic Fracture Regardless of Cemented Versus Cementless Femoral Stem Fixation

BackgroundIn osteoporotic patients, surgeons may utilize cemented femoral fixation to minimize risk of fracture. The purpose of this study was to compare 5-year implant survivability in patients who have osteoporosis who underwent elective total hip arthroplasty (THA) with cementless versus cemented fixation. MethodsA retrospective analysis of patients who have osteoporosis undergoing THA with either cemented or cementless femoral fixation was conducted using a national administrative claims database. Of the 18,431 identified THA patients who have osteoporosis, 15,867 (86.1%) underwent cementless fixation. The primary outcome was a comparison of the 5-year cumulative incidences of aseptic revision, mechanical loosening, and periprosthetic fracture (PPF). Kaplan–Meier and Multivariable Cox Proportional Hazard Ratio analyses were used, controlling for femoral fixation method, age, sex, a comorbidity scale, use of osteoporosis medication, and important comorbidity. ResultsThere was no difference in aseptic revision (Hazard’s Ratio (HR): 1.13; 95% Confidence Interval (CI): 0.79 to 1.62; P value: .500) and PPF (HR: 0.96; 95% CI: 0.64 to 1.44; P value: .858) within 5 years of THA between fixation cohorts. However, patients who had cemented fixation were more likely to suffer mechanical loosening with 5 years post-THA (HR: 1.79; 95% CI: 1.17 to 2.71; P-value: .007). ConclusionsWe found a similar 5-year rate of PPF when comparing patients who underwent cementless versus cemented femoral fixation for elective THA regardless of preoperative diagnosis of osteoporosis. While existing registry data support the use of cemented fixation in elderly patients, a more thorough understanding of the interplay between age, osteoporosis, and implant design is needed to delineate in whom cemented fixation is most warranted for PPF prevention.

Low Risk of Fracture Using a Cementless Triple-Tapered Collared Femoral Stem With Automated Impaction in Direct Anterior Approach Total Hip Arthroplasty

BackgroundDirect anterior approach (DAA) total hip arthroplasty (THA) has been associated with increased periprosthetic femoral fracture (PFF) risk. The aim of our study was to evaluate the fracture risk utilizing a triple-tapered, collared stem with automated impaction through the anterior approach. MethodsWe retrospectively reviewed consecutive DAA THA procedures at a single institution performed by 4 experienced DAA THA surgeons between 2019 and 2021. We collected data on age, sex, body mass index, preoperative diagnosis, and intraoperative and early postoperative PFF within 6 weeks postoperatively. Preoperative radiographs were evaluated to determine femoral neck-shaft angle and Dorr classification. We used Wilcoxon rank sum or Chi-square tests to assess differences between patients who did and did not have PFF. We also evaluated potential risk factors for PFF in unadjusted and adjusted regression analyses. In all, 24 PFFs (1.6%) occurred. There were 18 fractures (1.2%) recognized and managed intraoperatively (15 calcar, 2 greater trochanter, 1 posterior cortical). There were 6 PFFs (0.4%) identified postoperatively (5 greater trochanter, 1 diaphyseal), of which one required revision surgery. ResultsIdentified risk factors for fracture in adjusted regression models included women (odds ratio [OR] = 2.76, P = .047), preoperative coxa valga (OR = 4.54, P = .005), and coxa vara (OR = 2.85, P = .03). ConclusionsThe incidence of PFFs is low using a triple-tapered, collared cementless femoral stem with automated impaction through the DAA. Our findings agree with previous reports that have demonstrated women and preoperative valgus neck angle are risk factors for PFF.

Biomechanical analysis of different THA cementless femoral stem designs in physiological and osteoporotic bone during static loading conditions.

The influence of THA stem design on periprosthetic femoral fractures (PFFs) risk is subject of debate. This study aims to compare the effects of different cementless stem designs on stress-strain distributions in both physiological and osteoporotic femur under various loading conditions. A biomechanical study using finite-element analysis was conducted. Four models were developed: three with implanted femurs and a native one chosen as control. Each model was analyzed for both healthy and osteoporotic bone. The following stem designs were examined: short anatomical stem with femoral neck preservation, double-wedge stem, and anatomical standard stem. Three loading conditions were assessed: gait, sideways falling, and four-point bending. During gait in physiological bone, the anatomical stem and the short anatomical stem with femoral neck preservation showed stress distribution similar to the native model. The double-wedge stem reduced stress in the proximal area but concentrated it in the meta-diaphysis. In osteoporotic bone, the double-wedge stem design increased average stress by up to 10%. During sideways falling, the double-wedge stem exhibited higher stresses in osteoporotic bone. No significant differences in average stress were found in any of the studied models during four-point bending. In physiological bone, anatomical stems demonstrated stress distribution comparable to the native model. The double-wedge stem showed uneven stress distribution, which may contribute to long-term stress shielding. In the case of osteoporotic bone, the double-wedge stem design resulted in a significant increase in average stress during both gait and sideways falling, potentially indicating a higher theoretical risk of PFF.

What Are the Differences in Hospital Cost Associated With the Use of Cemented Versus Cementless Femoral Stems in Hemiarthroplasty and Total Hip Arthroplasty for the Treatment of Femoral Neck Fracture?

BackgroundThe purpose of this study was to determine if there is a difference in hospital costs associated with the use of cemented versus cementless femoral stems in hemiarthroplasty (HA) and total hip arthroplasty (THA) for the treatment of femoral neck fracture (FNF). MethodsThis retrospective cohort study utilizes the 2019 Medicare Provider Analysis and Review Limited Data Set. Patients undergoing arthroplasty for the treatment of FNF were identified. Patients were grouped by cemented or cementless femoral stem fixation. There were 16,148 patients who underwent arthroplasty for FNF available: 4,913 THAs (3,705 patients who had cementless femoral stems and 1,208 patients who had cemented femoral stems) and 11,235 HAs (6,099 patients who had cementless femoral stems and 5,136 who had cemented femoral stems). Index hospital costs were estimated by multiplying total charges by cost-to-charge ratios. Costs were analyzed using univariable and multivariable generalized linear models. ResultsCemented femoral stem THA generated 1.080 times (95% confidence interval, 1.06 to 1.10; P < .001), or 8.0%, greater index hospital costs than cementless femoral stem THA, and cemented femoral stem HA generated 1.042 times (95% confidence interval, 1.03 to 1.05; P < .001), or 4.2%, greater index hospital costs than cementless femoral stem HA. ConclusionsCemented femoral stems for FNF treated with either THA or HA are associated with only a small portion of increased cost compared to cementless femoral stems. Providers may choose the method of arthroplasty stem fixation for the treatment of FNF based on what they deem most appropriate for the specific patient.

Migration Characteristics of a Proximally Coated Collarless Femoral Stem: A Prospective 2-Year Radiostereometric Analysis Study.

Collared femoral stems have been considered to reduce the risk of early subsidence over collarless stems. However, with advances in material technology, new surface treatments have been introduced into cementless stem design to enhance primary fixation and long-term stability. This study aims to analyze the early migration behaviors of a proximally coated collarless femoral stem and cementless acetabular component and compare the outcomes with commercially available cementless stems and acetabular cups. A total of 24 patients (25 hips) undergoing total hip arthroplasty were recruited and followed up for 2years. All patients received a Masterloc femoral stem (Medacta International SA, Castel San Pietro, Switzerland) and an Mpact acetabular component (Medacta International SA, Castel San Pietro, Switzerland) with tantalum beads embedded during the operation. Radiographs for radiostereometric analysis were taken immediately postsurgery, 6-months, 1-year, and 2-years postoperatively. The median condition number for this study was 59. The median stem subsidence was-0.08 mm (-2.47 to 0.40) at 2 years. The median cup subsidence was-0.03 mm (-0.38 to 0.57) at 2 years. The migration of the Masterloc stem was less than that of other cementless collarless, as well as collared stems, as reported in literature. This study has demonstrated the high stability and fixation provided with the use of a collarless cementless stem. The subsidence seen in both this cementless femoral stem and acetabular cup at 2 years postoperative was below the range reported in literature for cementless collarless and collared stems.

Primary Stability of Collared and Collarless Cementless Femoral Stems - A Finite Element Analysis Study.

Primary stability of the femoral stem is important for the long-term results of cementless total hip arthroplasty. Cementless collared stems have been known to have higher stability than collarless stems when there is a contact between the collar and the calcar. The purpose of this study was to compare the stabilities of collared stem and collarless stem in 2 loading conditions: 1) flat walking and 2) stair climbing. We constructed 3 finite element models. In the first model, the collar had contact with the calcar. The second model had a 1 mm gap between the calcar and the collar. The third model was constructed with a collarless stem. The proximal femur around the stem was divided into 3 zones: the upper zone (Gruen zones 1 and 7), the middle zone (Gruen zones 2 and 6), and the lower zone (Gruen zones 3 and 5). The micromotion at the stem/bone interface was measured at each zone of the 3 models under the 2 loading conditions. The results showed that collared stems were more stable when the collar was in contact with the calcar than when a gap was left between the collar and the calcar. In particular, collar contact was highly effective in suppressing the micromotion proximal to the stem. Compared to the collarless stem, the collared stem had comparable stability when there was a gap at the collar and calcar interface and higher stability when there was contact between the collar and the calcar.

Primary Cementless Femoral Stems in Conversion Hip Arthroplasty After Failed Fixation of Intertrochanteric Fractures.

Salvage conversion hip arthroplasty is a viable solution to restore function and reduce pain after failed intertrochanteric hip fracture fixation. Our primary objective was to assess early outcomes achieved with primary cementless metaphyseal-engaging femoral stems for conversion hip arthroplasty compared with revision diaphyseal-engaging stems. This was a retrospective review of 70 patients with failed intertrochanteric hip fractures subsequently managed with conversion total hip arthroplasty or hemiarthroplasty. Thirty-five patients who underwent conversion using a primary cementless stem were compared with 35 patients who underwent conversion using a revision stem. The groups were similar regarding sex, body mass index, American Society of Anesthesiologists classification, preoperative diagnosis, and implants removed. Clinical and radiographic outcomes and complications were compared over a mean follow-up of 6 years. The primary stem cohort had a shorter mean hospital stay (3.03 vs 4.34 days, P=.028). There were no significant differences between the primary and revision cohorts regarding mean time to conversion (2.26 vs 1.75 years, P=.671), operative time (127 vs 131 minutes, P=.611), incidence of discharge to home (54.3% vs 37.1%, P=.23), postoperative complications (5.71% vs 5.71%, P=1.0), reoperations (5.71% vs 11.4%, P=.669), leg length discrepancy (5.33 vs 7.38 mm, P=.210), subsidence (20.0% vs 23.3%, P=.981), and Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement (78.6 vs 81.9, P=.723). We report comparable outcomes of conversion hip arthroplasty with the use of primary cementless and revision stems. Current primary cementless femoral stems may be considered for conversion hip arthroplasty for failed intertrochanteric fracture fixation. [Orthopedics. 2024;47(1):e6-e12.].

Multiscale Homogenization Techniques for TPMS Foam Material for Biomedical Structural Applications.

Multiscale techniques, namely homogenization, result in significant computational time savings in the analysis of complex structures such as lattice structures, as in many cases it is inefficient to model a periodic structure in full detail in its entire domain. The elastic and plastic properties of two TPMS-based cellular structures, the gyroid, and the primitive surface are studied in this work through numerical homogenization. The study enabled the development of material laws for the homogenized Young's modulus and homogenized yield stress, which correlated well with experimental data from the literature. It is possible to use the developed material laws to run optimization analyses and develop optimized functionally graded structures for structural applications or reduced stress shielding in bio-applications. Thus, this work presents a study case of a functionally graded optimized femoral stem where it was shown that the porous femoral stem built with Ti-6Al-4V can minimize stress shielding while maintaining the necessary load-bearing capacity. It was shown that the stiffness of cementless femoral stem implant with a graded gyroid foam presents stiffness that is comparable to that of trabecular bone. Moreover, the maximum stress in the implant is lower than the maximum stress in trabecular bone.

Five- to 12-Year Outcomes of a Short, Tapered, Highly Porous, Proximally Coated Cementless Femoral Stem

BackgroundShort cementless stems in total hip arthroplasty have gained increasing popularity, yet on-going studies of many of these implants are lacking. The aim of this study was to evaluate the minimum 5 year clinical and radiological results of a short, highly porous, single-tapered-wedge cementless femoral implant. MethodsA retrospective study of 281 hips in 256 patients who had a minimum 5-year follow-up and underwent primary total hip arthroplasty between 2010 and 2016 were evaluated. Clinical and radiological results, complications, and the presence of postoperative thigh pain were evaluated. ResultsThe mean follow-up was 8 years (range, 5 to 12 years). Clinically, patients had significant improvement in the average patient-related outcome scores postoperatively (Harris hip score: pre 47 versus post 95, University of California Los Angeles activity scale: pre 4 versus post 6, Western Ontario and McMaster Universities Arthritis Index: pre 51 versus post 3, Short Form (SF)-12 physical component summary : pre 32 versus post 52, Short Form-12 mental component summary: pre 49 versus post 55 (P < .001)). Radiographic signs of ingrowth were present in all hips. There were three patients (1.1%) who developed transient thigh pain postoperatively, all of which resolved with nonoperative management. ConclusionThis study provides the longest follow-up of this short, highly porous, single-tapered-wedge cementless femoral stem in the literature. This short, single-wedge stem with its highly porous coating demonstrated reproducible bone ingrowth in all patients and significant functional improvement with a very low rate of transient thigh pain.

Survival and complications at a minimum 5 years’ follow-up of the modular Mark-2 Extreme™ cementless femoral stem: Does the reduced modularity resolve the mechanical issues of the Mark-I stem?

IntroductionThe Extreme™ modular stem was developed for implant revision with metaphyseal-diaphyseal defect. Due to the high breakage rate, a new “reduced modularity” design has been introduced, but without reported results. We therefore conducted a retrospective assessment of (1) overall stem survival, (2) functional results, (3) osseointegration, and (4) the rate of complications, and notably of mechanical failure. HypothesisReduced modularity reduces the risk of revision surgery for mechanical failure. Material and methodsForty-five prostheses were implanted between January 2007 and December 2010 in 42 patients with severe bone defect (Paprosky≥III) or periprosthetic shaft fracture. Mean age was 69.6years (range: 44–91years). Minimum follow-up was 5years, for a mean 115.4months (range: 60–156months). The main study endpoint was femoral stem survival, counting all-cause explantation as event. Functional assessment comprised subjective rating of satisfaction, Postel Merle d’Aubigné (PMA) and Harris Hip scores, and Forgotten Joint Score (FJS). Whether the revision assembly was carried out in situ, in the patient's hip, or outside, on the operating table, was not known in 2 cases; in the other 43, assembly was in situ in 15 cases (35%) and on the operating table in 28 (65%). ResultsFive-year stem survival was 75.7% (95% CI: 61.9–89.5%), taking all causes of change together. Seventeen patients (45.9%) had complications, 13 (35.1%) requiring revision surgery, including 10 (27.0%) for stem replacement. Five patients (13.5%) had steam breakage at the junction between the metaphysis and the diaphyseal stem, 4 of which occurred within 2 years of implantation or of fixation of a periprosthetic fracture. Mean preoperative Harris score was 48.4 [IQR (25–75% interquartile range): 37–58] and PMA score 11.1 (IQR: 10–12), compared to respectively 74 (IQR: 67–89) and 13.6 (IQR: 12.5–16) at follow-up. Mean FJS at follow-up was 71.5 (IQR: 61–94.5). In the 15 in situ assemblies, there were 3 breakages (20%), compared to 2 (7.1%) in the 28 table assemblies (p=0.21). DiscussionThe stem breakage rate was high despite the reduced modularity, which concentrated all stress on a single junction but without reducing the risk of mechanical failure. Surgical technique was faulty in some cases, with in situ assembly of the metaphysis after implanting the diaphyseal stem, which does not respect the manufacturer's recommendations. Level of evidenceIV; retrospective study.

Influence of different CCD angles on osseointegration and radiological changes after total hip arthroplasty of a triple wedge shape cementless femoral stem: a prospective cohort study.

The purpose of this study was to evaluate the osseointegration and radiological outcomes in patients after total hip arthroplasty, hypothesizing different load patterns with one cementless stem design and different CCD angles (CLS Spotorno femoral stem 125° vs 135°). All cases of degenerative hip osteoarthritis fulfilling strict inclusion criteria were treated with cementless hip arthroplasty between 2008 and 2017. Ninety-two out of one hundred six cases were clinically and radiologically examined three and 12months after implantation. Two groups with each 46 patients were rendered prospectively and compared in clinical (Harris Hip Score) and radiological outcome. At final follow-up, no significant difference regarding Harris Hip Score was detected between the two groups (mean 99.2 ± 3.7 vs. 99.3 ± 2.5; p = 0.73). Cortical hypertrophy was found in none of the patients. Stress shielding was seen in a total of 52 hips (n = 27 vs. n = 25; 57% of the 92 hips). No significant difference regarding stress shielding was detected when comparing both groups (p = 0.67). Significant bone density loss was detected in Gruen zone one and two in the 125° group. The 135° group showed significant radiolucency in Gruen zone seven. No overall radiological loosening or subsidence of the femoral component was observed. According to our results, the use of a femoral component with a 125° CCD angle versus a 135° CCD did not result in a different osseointegration and load transfer with a clinically relevant significance.

The clinical effect of trochanteric slide osteotomy combined with a cementless femoral conical stem in total hip replacement for the treatment of Crowe type IV developmental dysplasia of the hip.

Total hip replacement (THR) for Crowe type IV developmental dysplasia of the hip (DDH) is still challenging due to specific joint deformities and the high incidence of post-operative complications. This study aimed to evaluate the clinical effect of trochanteric slide osteotomy (TSO) combined with a cementless femoral conical stem in THR for the treatment of Crowe type IV DDH. Thirty-one total hip replacements (26 patients) with Crowe type IV DDH were performed using TSO combined with a cementless femoral conical stem. Surgical outcomes were evaluated using leg length discrepancy (LLD), Harris hip score, and post-operative complications. The average pre-operative LLD was 51mm (range 46-58mm), decreasing to an average of 10mm (range 8-12mm) post-operatively. As a result, the post-operative incidence of the Trendelenburg sign significantly decreased compared with the pre-operative incidence (P< 0.05). Bony union was identified in 26 hips (83.9%), fibrous union in four (12.9%), and non-union in one (3.2%). No acetabular or femoral component loosening, dislocation, or deep infection around the component was found in any of the patients during the follow-up period (27 to 39 months). The average Harris hip score improved from 63.0 ± 3.0 (range 58-69) to 93.3 ± 2.0 (range 91-96). TSO combined with a cementless conical stem in THR is an appropriate option for patients with high congenital hip dislocation.

Experiences and results with a cementless femoral stem design: SL-PLUS MIA

Experiences and results with a cementless femoral stem design: SL-PLUS MIA

Radiographic Characteristics of the Femoral Nutrient Artery Canals in Total Hip Arthroplasty using Cementless Femoral Stem.

Accurate diagnosis of undisplaced periprosthetic femoral fracture (PFF) after hip arthroplasty is crucial, as overlooked PFF may affect its treatment and prognosis. The undisplaced PFF is often difficult to distinguish from radiolucent lines of nutrient artery canal (NAC) of the femur present on post-operative radiographs. We aimed to identify the radiographic features of NAC to distinguish them from PFFs. In this retrospective radiological study, a total of 242 cases in 215 patients with hip arthroplasty were analysed using pre-operative and post-operative anteroposterior (AP) and translateral (TL) radiographs. Interobserver agreement of the measurements was assessed by two independent experienced orthopaedic surgeons. The kappa value ranged from 0.83 to 0.87, indicating strong agreement according to the Landis and Koch criteria. The NACs were found pre-operatively in 94 (39.8%) cases on AP views and in 122 cases (50.4%) on TL views. The radiolucent lines were observed post-operatively in 42 (17.4%) on AP views and 122 (50.4%) on the TL views. three cases (1.2%) had a fracture around the stem that were detected on radiographs. One case with PFF presented simultaneously with NAC on the immediate post-operative radiographs. All patients were treated by conservative measures, and the radiolucent lines did not appear on follow-up radiographs. It is not easy to differentiate undisplaced PFFs that can occur after hip arthroplasty operation from NACs. However, accurate diagnosis is possible through careful observation and comparison of pre-operative and post-operative radiologic images.