Fixation In Total Hip Arthroplasty Research Articles

Cup Alignment Change after Screw Fixation in Total Hip Arthroplasty.

Background:Cup malalignment increase impingement, dislocation, cup migration, and polyethylene wear. Screw fixation for enhanced stability is the preferred option in cases of doubtful primary cup stability. There have been few studies about alignment changes after screw fixation, which may be another cause of cup malalignment. This study aimed to evaluate cup alignment change after screw fixation.Materials and Methods:Patients undergoing imageless navigation total hip arthroplasty using screws fixation for acetabular cup were corrected. After the press-fit cup was fully seated, the cup orientation was recorded. After screws were inserted, the cup orientation was recorded again to calculate the alignment change.Results:There were 99 cases with a mean age 63.7 years (25–93). Alignment change after screw fixation was found in 73 cases (73.7%). There were 56 cases (56.6%) with inclination angle change and the mean change was 2.21° (0°–8°). The inclination angle increased in 47 cases (47.5%) with 9 cases (9.1%) increased by 5° or more and decreased in 9 cases (9.1%). There was statistically significant difference between patients using one screw and patients using two or more screws in inclination angle change, 1.56° (0°–5°) and 3.4° (0°–8°), respectively (P = 0.0039). There was statistically significant correlation between inclination angle change and number of screws (r = 0.5401, P < 0.01). There were 49 cases (49.5%) with anteversion angle change and the mean change was 1.67° (0°–5°). The anteversion angle increased in 31 cases (31.3%), decreased in 18 cases (18.2%) with two cases (2%) decreased by 5° or more. There was significant difference between patients using one screw and patients using two or more screws in anteversion angle change, 1.46° (0°–5°) and 2.21° (0°–5°), respectively (P = 0.009). There was significant correlation between anteversion angle change and number of screws (r = 0.284, P = 0.048).Conclusions:Changes in cup alignment after screw fixation were detected in most cases. It is one possible cause of cup malalignment.

Comparison of trans-cortical and cancellous screws to press fit for acetabular shell fixation in total hip arthroplasty: A cadaveric study

BackgroundTotal hip arthroplasty complications are associated with mechanical loosening of the acetabular component, which may be attributed to the type of fixation used (press fit, trans-cortical screws, cancellous screws). Therefore, the purpose of this study was to compare trans-cortical and cancellous screws to press fit for fixation of the acetabular shell. MethodsFive cadaveric pelvis specimens were hemisected (N = 10) at the sacroiliac joint. Each hemi-pelvis was initially tested with a press fit cup followed by the left and right pairs being randomized to either a cancellous or trans-cortical screw condition. Each fixation was tested by applying a load to a rod inserted into the centre of the acetabular cup at 0.5 mm/s, until failure occurred. The failure force, failure moment, and the rotation angle of the cup at failure were calculated. FindingsThe cups fixated with a trans-cortical screw failed at a significantly greater mean [SD] force (1046.20 [386.52] N). The trans-cortical screws also significantly increased the angle of failure 46.29 (16.90) ° compared to the press-fit cups (6.73 [4.59] °). Finally, there was a significant increase in the failure moment, such that, the trans-cortical condition failed at a mean (SD) moment of 53.75 (16.24) Nm compared to 9.59 (1.85) Nm and 32.15 (18.16) Nm for the press fit and cancellous (p = 0.044) conditions, respectively. InterpretationThe acetabular shells that were fixated with trans-cortical screws provide greater stability compared to the press-fit cups or cancellous screws.

Hybrid Fixation for Total Hip Arthroplasty Showed Improved Survival Over Cemented and Uncemented Fixation: A Single-Center Survival Analysis of 2156 Hips at 12-18 Years

BackgroundDespite increased use of uncemented and hybrid fixation, there is little evidence of their superiority over cemented implants. The aim of this study is to compare the long-term survivorship of cemented, hybrid and uncemented total hip arthroplasty (THA) at varying ages. MethodsA total of 2156 hips (1315 cemented, 324 uncemented, and 517 hybrid) were performed in a single center between 1999 and 2005 with follow-up through to 2017. Registry and local databases were used to determine revision rates and cause. Unadjusted and adjusted competing risk survival analysis was performed. ResultsThe cumulative incidence of all-cause revision at 18 years was cemented 10.9%, uncemented 8.9%, and hybrid 6.5%. Cemented fixation had a statistically significant higher risk of all-cause revision than hybrid in the adjusted model for all ages to 65 years (subhazard ratios [SHRs], 2.28-4.67) and a higher risk of revision for loosening, wear, or osteolysis at all ages (SHRs, 3.25-6.07). Uncemented fixation showed no advantage over hybrid fixation at any age, but did show advantages over cemented at younger ages (≤60 years) for all-cause revision (SHRs, 2.3-4.3). ConclusionHybrid fixation with conventional polyethylene shows an advantage over cemented hips at all ages. Uncemented THA showed improved survival over cemented only at younger ages and no advantage over hybrid THA.

Definition of a Novel Proximal Femur Classification in the Sagittal Plane According to the Femur Morphometric Analysis

BackgroundStudies on prosthesis positioning and implant design in total hip arthroplasty (THA) have generally focused on the anatomy of the proximal femur in the coronal plane. The aim of this study was to investigate the proximal femur morphology in the sagittal plane to provide better positioning of the femoral component in THA and contribute to the determination of proximal femur morphology through possible outcomes that can be shown also by considering the sagittal plane in the selection and design of the femoral component. MethodsComputerized tomography scans were obtained from 270 femoral bones belonging to adult skeletons, followed by 3D reconstruction using Leonardo Dr/Dsa Va30a software (Siemens, Erlangen, Germany) and measurements. Canal widths were measured in the coronal and sagittal planes at the lesser trochanter (LT) level, at 20 millimeters proximal to the LT(LT+20) and at various levels distal to the lesser trochanter in 25 mm jumps up to 200 mm from the lesser trochanter. ResultsThe average width was wider at the level of the lesser trochanter and all points distal to it in the sagittal plane compared to the coronal plane except LT−200 mm. At each levels from LT−25 to LT−175, the differences were statistically significant (P < .05). The ratio of the femoral width at the lesser trochanter level to the width 50 mm distal to the LT was stated as the most prevalent one, and a novel classification in the sagittal plane was developed in accordance with these findings. ConclusionA novel and simple classification in the sagittal plane was developed based on the findings of this study, and this classification may improve the accuracy, validity, and reliability of femoral stem fixation in total hip arthroplasty.

Changes in acetabular component alignment due to screw fixation in patients with hip dysplasia.

Adequate initial stability of the acetabular cup is essential for total hip arthroplasty (THA). However, changes in the alignment of the acetabular component caused by screw fixation are concerning in patients with inadequate bone stock. This study aimed to investigate the effects of screw fixation on the alignment of the acetabular component in THA patients with hip dysplasia. We retrospectively examined 256 hips (range 28-87 years) that underwent THA using a navigation system. Patients were divided into 2 groups based on the presence or absence of changes in the alignment of the intraoperative acetabular cup, and univariate and multivariate analyses were performed to identify factors that were predictive of changes in acetabular component alignment after screw fixation in 2 dimensions: inclination and anteversion. Screw fixation led to a mean change in inclination of 1.6° (range 0-10°) and a mean change in anteversion of 1.4° (range 0-14°). The Crowe classification, the presence of bone cysts, and the use of an inferior quadrant screw were identified as factors that correlated with acetabular cup alignment changes in inclination (odds ratios, 6.01, 5.94 and 0.03, respectively). Only the Crowe classification was identified as a factor that correlated with intraoperative alignment changes in anteversion (odds ratio, 2.08). Screw fixation altered the acetabular cup alignment. The inclination changes were related to the extent of the dysplasia, and the risk was reduced when the inferior quadrant screw was used. Surgeons should use caution during screw fixation in THAs performed on severely dysplastic hips.

Longitudinal morphological change of acetabular subchondral bone cyst after total hip arthroplasty in developmental dysplasia of the hip.

The purpose of this study is to clarify morphological changes of acetabular subchondral bone cyst after total hip arthroplasty for osteoarthritis secondary to developmental dysplasia of the hip. Two hundred and sixty-one primary cementless total hip arthroplasties of 208 patients, 18 males, 190 females, were retrospectively reviewed. Morphological changes of subchondral bone cyst were evaluated by computed tomography (CT). The mean cross-sectional area of the cyst from CT scans at 3months postoperatively and after 7-10years (average 8.4years) were compared. Acetabular subchondral bone cysts were found in 49.0% of all cases in preoperative CT scans. There was no cyst which was newly recognized in CT scan performed after postoperative 7-10years. All the cross-sectional areas of the cysts evaluated in this study were reduced postoperatively. This study revealed that acetabular subchondral bone cysts do not increase or expand after total hip arthroplasty and indicated that the longitudinal morphological change of acetabular bone cysts in patients of developmental dysplasia of the hip do not influence long-term implant fixation in total hip arthroplasty.

The Influence of Contamination and Cleaning on the Strength of Modular Head Taper Fixation in Total Hip Arthroplasty

BackgroundIntraoperative interface contamination of modular head-stem taper junctions of hip implants can lead to poor fixation strength, causing fretting and crevice corrosion or even stem taper fracture. Careful cleaning before assembly should help to reduce these problems. The purpose of this study was to determine the effect of cleaning (with and without drying) contaminated taper interfaces on the taper fixation strength. MethodsMetal or ceramic heads were impacted onto titanium alloy stem tapers with cleaned or contaminated (fat or saline solution) interfaces. The same procedure was performed after cleaning and drying the contaminated interfaces. Pull-off force was used to determine the influence of contamination and cleaning on the taper strength. ResultsPull-off forces after contamination with fat were significantly lower than those for uncontaminated interfaces for both head materials. Pull-off forces after application of saline solution were not significantly different from those for uncontaminated tapers. However, a large variation in taper strength was observed, pull-off forces for cleaned and dried tapers were similar to those for uncontaminated tapers for both head materials. ConclusionIntraoperative contamination of taper interfaces may be difficult to detect but has a major influence on taper fixation strength. Cleaning of the stem taper with saline solution and drying with gauze directly before assembly allows the taper strength of the pristine components to be achieved. Not drying the taper results in a large variation in pull-off forces, emphasizing that drying is essential for sufficient and reproducible fixation strength.

Increased risk of intraoperative and early postoperative periprosthetic femoral fracture with uncemented stems

Background and purpose — The use of uncemented fixation in total hip arthroplasty (THA) is increasing. Registry studies have indicated an increased risk of revision of uncemented implants due to early periprosthetic femoral fracture. In this paper, we describe the incidence and predisposing factors for intraoperative and early postoperative (≤ 90 days) periprosthetic femoral fractures after cemented and uncemented THA.Patients and methods — This was a prospective observational study in 8 Danish high-volume centers from February 2010 to November 2013. We used the 90-day follow-up from the Danish National Patient Registry and patient records. We obtained intraoperative information from the Danish Hip Arthroplasty Registry and from surgical notes.Results — Of 7,169 primary consecutive THAs, 5,482 (77%) were performed using uncemented femoral components. The total incidence of periprosthetic femoral fractures ≤ 90 days postoperatively was 2.1% (n = 150). 70 fractures were detected intraoperatively (46 required osteosynthesis). 51 postoperatively detected fractures occurred without trauma (42 of which were reoperated) and 29 were postoperative fall-related fractures (27 of which were reoperated). 134 fractures (2.4%) were found in uncemented femoral components and 16 (0.9%) were found in cemented femoral components (p < 0.001). Uncemented femoral stem (relative risk (RR) = 4.1, 95% CI: 2.3–7.2), medically treated osteoporosis (RR =2.8, CI: 1.6–4.8), female sex (RR =1.6, CI: 1.1–2.2), and age (RR =1.4 per 10 years, CI: 1.2–1.6) were associated with increased risk of periprosthetic femoral fracture when analyzed using multivariable regression analysis.Interpretation — Uncemented femoral components were associated with an increased risk of early periprosthetic femoral fractures, especially in elderly, female, and osteoporotic patients.

Screw-hole clusters in acetabular cups: a morphological study of optimal positioning of screw-holes.

Rigid and safe transacetabular screw fixation in total hip arthroplasty (THA) is achieved by pursuing deeper bone stock and avoiding injuries to the neurovascular structures, but these efforts can be restricted by the distribution of screw-holes on cups by the manufacturer. We therefore tried to determine: (i) optimal screw-hole positions on cups to allow anatomical placement of screws; (ii) rationality of the basic 3-screw-hole cluster on commercial cups; and (iii) the optimum method for placing commercial cups in accordance with acetabular anatomy. Periacetabular osseous structure of 64 hips and arterial structures of 50 hips were three-dimensionally reconstructed. Simulated transacetabular screw fixation during THA was performed in these hips with 3 different screw lengths (15, 25, and 35 mm) to define deeper and safer screw trajectories. Screw-hole locations of 7 commercially available cups were measured and matched with the periacetabular anatomy. When the cup was placed into the acetabulum at 45° of abduction and 20° of anteversion, the optimal locations of 2 screw-holes on the cups were at 30° and 64° of latitude, with a 35° separation angle. The inversetriangle distribution pattern was safer than the triangle pattern in basic 3-screw-hole-cluster cups. When placing the commercial cups, 5°-10° of anterior rotation can be added to allow better screw trajectories. Our study determined optimal screw-hole positions and their distribution pattern on cups. We describe methods to place the commercial cups that are not designed according to acetabular anatomy.

Early Results of Acetabular Reconstruction After Wide Periacetabular Oncologic Resection.

Reliable acetabular fixation in total hip arthroplasty following periacetabular resections is challenging. Tantalum components have been successfully implemented for difficult revision arthroplasties, but, to our knowledge, have not been reported for acetabular reconstruction following oncologic periacetabular resection. The primary purpose of the current study was to determine the early clinical outcomes, complications, and radiographic findings for acetabular reconstruction after oncologic periacetabular resection. In addition, a novel classification scheme for primary periacetabular resections and reconstructions is presented. We reviewed 10 consecutive patients treated with tantalum acetabular reconstruction following periacetabular resection. All patients had a primary acetabular malignancy including chondrosarcoma (n = 7) and osteosarcoma (n = 3). The cohort included 6 males (60%). The mean age was 54 years (range, 30 to 73 years). The mean follow-up was 59 months (range, 8 to 113 months). At the most recent follow-up, 9 patients were alive and 1 had died of the respective disease. All patients obtained full ambulatory status with the use of gait aids. Postoperative complications included dislocation (n = 3), wound-healing disturbance (n = 1), and deep venous thrombosis (n = 1). Two patients underwent reoperations for recurrent dislocations. The mean postoperative Harris hip score was 75 points (range, 49 to 92 points). Preliminary results of tantalum reconstruction following periacetabular resections provide reasonable improvement in early clinical outcomes and stable fixation in situations with massive bone loss and compromised bone quality. As expected due to the lack of a functioning abductor mechanism from the wide oncologic resection, early dislocations remain a concern. As such, we now consider the primary use of increasing constraint, but it must be balanced with the often compromised host bone. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Porous Femoral Fixation in Total Hip Arthroplasty with Short Anatomical Stem: Radiographic Evaluation.

BackgroundHip prostheses with short anatomical stems were designed for metaphyseal fixation and to spare bone stock. We present a study of a short anatomical femoral stem used in all age groups of patients with Dorr A and B type of femora.MethodsWe reviewed radiographs of 85 hips in 74 patients who had a cementless total hip arthroplasty with a short anatomical 80 mm femoral stem designed to achieve pure metaphyseal fixation. A ream-only technique was used for femoral canal preparation in all patients. At each follow-up, radiological evaluation was performed for stem alignment, proximal metaphyseal fill, subsidence, status of biological fixation of the femoral stem, heterotrophic ossification, radiolucency, osteolysis, and limb length discrepancy of the stem. Acetabular components were evaluated for positioning, acetabular bone coverage, and radiolucent and osteolytic lesions.ResultsThe final mean alignment of femoral stem was 2° valgus. The average intramedullary fill by the stem at the proximal level of the lesser trochanter was 93% in the coronal plane and 88% in the sagittal plane. No components were considered to be undersized. Thirteen hips (15.2%) presented radiolucent lines (10 hips < 1 mm in width and 3 hips [3.5%] 2 mm in width) and 100% of them were not progressive with respect to the last follow-up radiograph. All of the stems had excellent fixation by demonstrating bone ingrowth at the latest follow-up. At the last follow-up, heterotopic ossification was noted in 5 hips. The mean preoperative limb length discrepancy was 9.3 mm and the mean postoperative discrepancy was 3.8 mm. The mean acetabular component angle of the 85 components was 41.2° with a mean anteversion of 22.1°. At the last follow-up, there were no revisions of the femoral component. One patient, 25 months after the index operation, required an acetabular component revision because of recurrent hip dislocation. There were no radiological signs of loosening in any of the short-stem prostheses at the last examination.ConclusionsThe short, metaphyseal-fitting anatomic cementless femoral stem provided stable fixation without relying on diaphyseal fixation.

Risk of early mortality after cemented compared with cementless total hip arthroplasty: a nationwide matched cohort study.

It has been suggested that cemented fixation of total hip arthroplasty (THA) is associated with an increased peri-operative mortality compared with cementless THA. Our aim was to investigate this through a nationwide matched cohort study adjusting for age, comorbidity, and socioeconomic background. A total of 178 784 patients with osteoarthritis who underwent either cemented or cementless THA from the Swedish Hip Arthroplasty Register were matched with 862 294 controls from the general population. Information about the causes of death, comorbidities, and socioeconomic background was obtained. Mortality within the first 90 days after the operation was the primary outcome measure. Patients who underwent cemented THA had an increased risk of death during the first 14 days compared with the controls (hazard ratio (HR) 1.3, confidence interval (CI) 1.11 to 1.44), corresponding to an absolute increase in risk of five deaths per 10 000 observations. No such early increase of risk was seen in those who underwent cementless THA. Between days 15 and 29 the risk of mortality was decreased for those with cemented THA (HR 0.7, CI 0.62 to 0.87). Between days 30 and 90 all patients undergoing THA, irrespective of the mode of fixation, had a lower risk of death than controls. Patients selected for cementless fixation were younger, healthier and had a higher level of education and income than those selected for cemented THA. A supplementary analysis of 16 556 hybrid THAs indicated that cementation of the femoral component was associated with a slight increase in mortality up to 15 days, whereas no such increase in mortality was seen in those with a cemented acetabular component combined with a cementless femoral component. This nationwide matched cohort study indicates that patients receiving cemented THA have a minimally increased relative risk of early mortality that is reversed from day 15 and thereafter. The absolute increase in risk is very small. Our findings lend support to the idea that cementation of the femoral component is more dangerous than cementation of the acetabular component. Cite this article: Bone Joint J 2017;99-B:37-43.

Does the Canal Fill Ratio and Femoral Morphology of Asian Females Influence Early Radiographic Outcomes of Total Hip Arthroplasty With an Uncemented Proximally Coated, Tapered-Wedge Stem?

BackgroundNoncement femoral fixation in total hip arthroplasty (THA) has been gaining popularity. However, owing to the numerous varieties of uncemented stems and differing types of femoral stem morphology, it is unclear whether the clinical outcomes of all uncemented stems are equal. The aim of this study was to investigate the relationships between canal fill ratio and femoral morphology and early radiologic outcomes in Japanese patients who underwent THA with an uncemented proximally hydroxyapatite-coated, tapered-wedge stem. MethodsWe retrospectively reviewed 103 patients who had undergone THA using a single proximally coated tapered-wedge stem. The relationships between canal fill ratio and femoral morphology and early radiologic outcomes after THA with those stem were investigated. ResultsEighty-one hips were analyzed after inclusion and exclusion criteria were applied. Failed osteointegration proximally was observed in 4 hips (4.9%). Canal flare index was significantly greater in hips with failed osteointegration than in those with successful osteointegration (P = .009). Distal hypertrophy was observed in 14 hips (17.3%). Proximal-distal matching ratio was significantly lower in hips with distal hypertrophy than in those without (P = .01). Canal fill ratio at 2 cm above the lesser trochanter was smaller in hips with failed osteointegration and distal hypertrophy than in those without (P = .02). ConclusionSuboptimal radiologic changes were seen with greater distal fill with smaller proximal fill and with a narrow femoral canal. It is important to select the stem that can achieve the original concept of intended primary and secondary fixation areas.

A cemented acetabular component with a reinforcement cross provides excellent medium-term fixation in total hip arthroplasty after pelvic irradiation

Conventional cemented acetabular components are reported to have a high rate of failure when implanted into previously irradiated bone. We recommend the use of a cemented reconstruction with the addition of an acetabular reinforcement cross to improve fixation. We reviewed a cohort of 45 patients (49 hips) who had undergone irradiation of the pelvis and a cemented total hip arthroplasty (THA) with an acetabular reinforcement cross. All hips had received a minimum dose of 30 Gray (Gy) to treat a primary nearby tumour or metastasis. The median dose of radiation was 50 Gy (Q1 to Q3: 45 to 60; mean: 49.57, 32 to 72). The mean follow-up after THA was 51 months (17 to 137). The cumulative probability of revision of the acetabular component for a mechanical reason was 0% (0 to 0%) at 24 months, 2.9% (0.2 to 13.3%) at 60 months and 2.9% (0.2% to 13.3%) at 120 months, respectively. One hip was revised for mechanical failure and three for infection. Cemented acetabular components with a reinforcement cross provide good medium-term fixation after pelvic irradiation. These patients are at a higher risk of developing infection of their THA.

Navigated Acetabular Cup Fixation for Acetabular Deformity or Revision Total Hip Arthroplasty.

PurposeTo evaluate the usefulness of navigated acetabular cup fixation for total hip arthroplasty in patients with acetabular deformity or revision total hip arthroplasty.Materials and MethodsThis study enrolled 28 patients with at least 12 months' follow-up. The safe zone of the acetabular cup was defined as 40°±10°in inclination and 15°±10°in anteversion. The authors used the navigation and radiographic data to determine whether the acetabular cup was located within the safe zone or not. To evaluate the clinical outcomes, preoperative and last follow-up Harris hip scores were checked, and the occurrence of complications was evaluated.ResultsAccording to the navigation data, the mean inclination and anteversion were 38.5°±4.7°(range, 32°-50°) and 16.6°±4.0°(range, 8°-23°), respectively. According to the radiographic data the mean inclination and anteversion were 40.5°±4.6°(range, 32°-50°) and 19.4°±4.2°(range, 8°-25°), respectively. In both cases, all values were within the safe zone. Harris hip score was improved in all patients from preoperative 52.3±14.4 points (range, 29-87 points) to 88.0±9.0 points (range, 65-99 points) at the last follow-up. There was no dislocation or loosening of both cases.ConclusionNavigated acetabular cup fixation is a useful technique for total hip arthroplasty in patients with acetabular deformity or revision total hip arthroplasty because it prevents the malposition and related complications.

The Geometry of the Bone Structure Associated with Total Hip Arthroplasty

Close adaptation of the prosthesis to the bone is the key to achieving optimal stability and fixation for total hip arthroplasty (THA). However, there have been no adequate studies of bone morphology, especially in different races. The aim of this study was to analyze the geometry of the acetabulum and proximal femur of people from South China, based on three-dimensional reconstruction, and to detect differences between different population subsets. CT scans were performed on 80 healthy volunteers (160 hips) from South China, comprising 40 males (80 hips) and 40 females (80 hips). The images were imported into Mimics 10.01 to perform 3D reconstruction. THA-associated anatomical parameters were measured and compared with other published data. In comparison with published data, it seemed that people from South China have smaller acetabular abduction angle, larger acetabular supro-inferior diameter, larger neck-shaft angle, smaller offset, thinner femoral shaft and more proximal isthmus, which needed to be further confirmed. There were significant differences between the genders in most parameters. As significant differences in canal flare index (CFI) and distal canal flare index (DCFI) were found between genders, it was concluded the most significant differences lay in the isthmus of the femur. Among the femora, according to Noble’s classification we identified more normal types and fewer stovepipe and champagne-flute types than expected from the literature, indicating that uncemented prostheses would be suitable for most people from South China. Our findings reveal that simply choosing the smallest of a series of prostheses would not necessarily provide a good fit, due to the different trends from the proximal to the distal part of the femur. Significant variation exists in THA-associated anatomy between genders and population subsets. It is therefore imperative that each patient receives individual consideration rather than assuming all patients have the same anatomy, especially for different races.

Osseointegration in the elderly

Osseointegration is a term that refers to the formation of a direct interface between an implant and bone without intervening soft tissue. Cementless femoral fixation in total hip arthroplasty is dependent on mechanical and biological factors that affect implant stability and long-term outcome. Osteoporosis leads to morphological and biological alterations in the proximal femur that adversely affect both mechanical stability of implant and biological response of bone, making it more challenging to achieve a valid osseointegration.

Press-fit cementless acetabular fixation with and without screws

Cementless acetabular fixation for total hip arthroplasty (THA) is widely used. The question of using screws for a better primary and secondary acetabular fixation has been discussed in the literature in recent years. The aim of this meta-analysis was to compare fixation of acetabular cups with and without screws in total hip arthroplasty. Electronic databases Embase, PubMed and Cochrane Library were used to search for randomised controlled trials reported through May 2013 of cementless acetabular fixation for THA with and without screws. Two independent reviewers assessed the trials for eligibility and quality. All related data matching our standards were abstracted for meta-analysis by RevMan 5.0. Evaluation criteria included revisions, migration and osteolysis. A total of 1,130 THAs enrolled into five trials were included in this meta-analysis. All studies compared fixation of acetabular cups with and without screws, and our pooled data showed no statistical significance between the two surgical methods in revision, migration and osteolysis. There is no significant difference between cementless acetabular fixation for THA with and without screws in revisions, migration or osteolysis.

Cementless femoral stems: Is there an optimum?

The use of cementless fixation in total hip arthroplasty has been associated with excellent results in several long-term follow-up studies. A majority of total hip arthroplasty performed in the United States has capitalized on this concept, utilizing both cementless acetabular and femoral components. Since the advent of cementless fixation, there has been a substantial evolution in femoral stem design. The individual stem geometry and the location of the porous coating for bone ingrowth are critical to the surgical technique for bone preparation and guide the ensuing success, complications, and even potentially the postoperative rehabilitation.

Adverse Local Tissue Reaction Arising from Corrosion at the Femoral Neck-Body Junction in a Dual-Taper Stem with a Cobalt-Chromium Modular Neck

Femoral stems with dual-taper modularity were introduced to allow additional options for hip-center restoration independent of femoral fixation in total hip arthroplasty. Despite the increasing availability and use of these femoral stems, concerns exist about potential complications arising from the modular neck-body junction. This was a multicenter retrospective case series of twelve hips (eleven patients) with adverse local tissue reactions secondary to corrosion at the modular neck-body junction. The cohort included eight women and three men who together had an average age of 60.1 years (range, forty-three to seventy-seven years); all hips were implanted with a titanium-alloy stem and cobalt-chromium-alloy neck. Patients presented with new-onset and increasing pain at a mean of 7.9 months (range, five to thirteen months) following total hip arthroplasty. After serum metal-ion studies and metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) revealed abnormal results, the patients underwent hip revision at a mean of 15.2 months (range, ten to twenty-three months). Tissue specimens were examined by a single histopathologist, and the retrieved implants were studied with use of light and scanning electron microscopy. Serum metal levels demonstrated greater elevation of cobalt (mean, 6.0 ng/mL) than chromium (mean, 0.6 ng/mL) or titanium (mean, 3.4 ng/mL). MRI with use of MARS demonstrated adverse tissue reactions in eight of nine patients in which it was performed. All hips showed large soft-tissue masses and surrounding tissue damage with visible corrosion at the modular femoral neck-body junction. Available histology demonstrated large areas of tissue necrosis in seven of ten cases, while remaining viable capsular tissue showed a dense lymphocytic infiltrate. Microscopic analysis was consistent with fretting and crevice corrosion at the modular neck-body interface. Corrosion at the modular neck-body junction in dual-tapered stems with a modular cobalt-chromium-alloy femoral neck can lead to release of metal ions and debris resulting in local soft-tissue destruction. Adverse local tissue reaction should be considered as a potential cause for new-onset pain in patients with these components, and early revision should be considered given the potentially destructive nature of these reactions. A workup including serologic studies (erythrocyte sedimentation rate and C-reactive protein), serum metal levels, and MARS MRI can be helpful in establishing this diagnosis.