The major failure mode of cemented or non-cemented acetabular fixation is osteolysis produced by polyethylene debris and biologic reaction to this material. A monoblock acetabular non-cemented component offers advantages in reducing the failure mechanism of acetabular cups. First, because the polyethylene is fixed to the metal shell there is no motion between the shell and the liner as is seen with modular components. Therefore extra-articular polyethylene wear debris is not generated. Secondly, there is no need for a locking mechanism which may fail and from which metallic debris may be produced. Thirdly, no screw holes are present on the back of the monoblock cup increasing the surface area for ingrowth and eliminating an entrance point for wear debris to access the floor of the acetabulum. Avoidance of the use of screws also prevents the possibility of neurovascular injury during screw insertion. Fourthly, by adding an elliptical configuration to a monoblock cup the dome of the shell is the same dimension as the reamed diameter allowing for improved coaptation of shell to acetabular floor. By increasing the diameter at the rim secure press fit is achieved without sacrificing contact at the dome. There are disadvantages to a monoblock cup and these include the need for a revision liner mechanism should there be a need to replace the polyethylene liner. Additionally, if secure stabilisation is not achieved, the cup cannot be converted to screw fixation. In a radiologic review of 661 acetabular components, 5.1% of cups were noted to have a polar dome acetabular gap of greater than 1.5 mm on the immediate postoperative radiograph. These patients were followed for a minimum of two years and there was noted shift in implant position in only one patient. Gaps tended to lessen in degree and fill in with bone in almost all cases. The clinical result was not compromised by the presence of a dome gap. In a short-term follow-up of 6 years, 1843 elliptical monoblock acetabular cups have been inserted with greater than two-year follow-up in 972 hips. There have been no mechanical failures requiring revision. Two patients have been revised for instability and one for infection. The need to convert to a cup with screw fixation because of poor press fit is less than 2%

There are many types and articulating surfaces in acetabular cups. Most of the designs currently available are modular, the liner snapping into a locking mechanism of some type. These modular inserts may be polyethylene, usually highly crosslinked polyethylene, or ceramic. Metal shells used in metal-on-metal devices are usually of a monoblock design. The elliptical monoblock design has been available for 20 years and was originally made of Titanium with a compression molded polyethylene liner. Tantalum (trabecular metal) was used as the shell material in the more recent designs and the polyethylene is actually molded directly into the tantalum framework. Monoblock acetabular components have a number of advantages. They do not allow access to the ilium because there are no holes in the socket shell with the monoblock construct. They require no locking mechanism which may increase metallic debris. No back surface liner wear can occur because all motion is eliminated at the liner/shell interface. However, because of this absence of screw holes there is an inability to visualise the floor of the acetabulum and perfect coaptation between the shell and the acetabular floor may not occur. The presence of dome gaps of greater than 1.5 mm have been noted in 5% of these components but these have not compromised implant stability and in a review of over 600 cups there has been no change in implant position. Results with over 258 monoblock cups with a minimum of 10-year follow-up (10–15 years) have been excellent. (Poultsides, et al) The incidence of pelvic osteolysis was not seen in any patient in this series. There were 3 revisions for instability but none for mechanical failure. There were 3 femoral revisions for loosening but the cup was intact and not revised in these patients. Utilizing the Livermore measurement method polyethylene wear averages 0.08 mm per year (0.06 – 0.13 mm) and there have been no revisions for wear. Radiographic evaluation demonstrates stable bony interface in all patients. At minimum 10- year follow-up the monoblock acetabular component with compression molded polyethylene confirms the theoretical advantages of this design and results have been excellent. Moen et al have demonstrated no osteolysis in CT scans in tantalum monoblock cups at a follow up of 10.3 years

There are many types and articulating surfaces in acetabular cups. Most of the designs currently available are modular, the liner snapping into a locking mechanism of some type. These modular inserts may be polyethylene, usually highly crosslinked polyethylene, or ceramic. Metal shells used in metal on metal devices are usually of a monoblock design. The elliptical monoblock design has been available for 20 years and was originally made of Titanium with a compression molded polyethylene liner. Tantalum (trabecular metal) was used as the shell material in the more recent designs and the polyethylene is actually molded directly into the tantalum framework. Monoblock acetabular components have a number of advantages. They do not allow access to the ilium because there are no holes in the socket shell with the monoblock construct. They require no locking mechanism which may increase metallic debris. No back surface liner wear can occur because all motion is eliminated at the liner/shell interface. However, because of this absence of screw holes there is an inability to visualise the floor of the acetabulum and perfect coaptation between the shell and the acetabular floor may not occur. The presence of dome gaps of greater than 1.5mm have been noted in 5% of these components but these have not compromised implant stability and in a review of over 600 cups there has been no change in implant position. The elliptical shape of the cup makes the mouth of the acetabular component 2mm greater than the dome so that an exceptionally strong acetabular rim fit results. Results with over 258 monoblock cups with a minimum of 10-year follow up (10–15 years) have been excellent (Poultsides, et al.). The incidence of pelvic osteolysis was not seen in any patient in this series. There were 3 revisions for instability but none for mechanical failure. There were three femoral revisions for loosening but the cup was intact and not revised in these patients. Utilising the Livermore measurement method polyethylene wear averages 0.08mm per year (0.06mm-0.13mm) and there have been no revisions for wear. Radiographic evaluation demonstrates stable bony interface in all patients. At minimum 10-year follow up the monoblock acetabular component with compression molded polyethylene confirms the theoretical advantages of this design and results have been excellent. Moen et al. have demonstrated no osteolysis in CT scans in tantalum monoblock cups at a follow up of 10.3 years

There are many types of articulating surfaces in uncemented acetabular cups. Most of the designs currently available are modular, with the shell snapping into a locking mechanism of some type. An Elliptical Monoblock design has been available for 15 years and was originally made of titanium with a factory assembled compression molded polyethylene liner. Porous tantalum (trabecular metal) was used as the shell material in a subsequent more recent design and in this design the polyethylene is actually molded directly into the tantalum framework.

Monoblock acetabular components do not allow particulate access to the ilium via screw holes and require no surgeon assembled locking mechanism which may increase backside wear and metallic debris. There are no holes in the socket because of the monoblock construct. Because of this absence of screw holes there is an inability to visualise the floor of the acetabulum and perfect coaptation between the shell and the acetabular floor may not occur. The presence of dome gaps of greater than 1.5mm have been noted in 5% of these components but these have not compromised implant stability and in a review of over 600 cups there has been no change in implant position. The Elliptical shape of the cup makes the mouth of the acetabular component 2mm greater than the dome so that an exceptionally strong acetabular rim fit results.

Results will be reported from two major institutional series with a minimum 10-year follow-up (range 10–15 years). No pelvic osteolysis was not seen in any patient in either series. In the HSS series of 250 cases with minimum 10 year follow up there were 4 revisions for instability but none for mechanical failure. There were three femoral revisions for loosening but the cup was intact and not revised in these patients. Utilising the Livermore measurement method polyethylene wear averages 0.8mm per year (0.6mm-1.3mm) and there have been no revisions for wear. Radiographic evaluation demonstrates stable bony interface in all patients. In a Mayo series of prospectively randomised patients also at minimum 10 years there was no lysis and only one case of aseptic loosening in a beaded titanium cup. At minimum 10-year follow up two similar elliptical monoblock cementless acetabular component designs with compression molded polyethylene have confirmed the theoretical advantages of this design concept and demonstrate long term results that have been excellent to date.

In almost all countries performing Total Hip Replacement (THR), dislocation is one of the major reasons for revision. Hence, in the last years the trend to larger bearings has been observed, following an improve in the bearing materials, the operation technique, and fixation techniques of stem and shell. Larger bearings allow for more range of motion and higher stability than conventional 28 mm bearing couples, leading to a better postoperative mobility. On the other hand, size limitations on the acetabular side are given by the anatomy of the human pelvic bone as well as the deformation and fracture behaviour of the used artificial materials. Therefore, the best solution to be achieved provides a maximum physiological outcome along with a minimised risk of intraoperative and in-vivo failures.

Investigating the wall thickness of the metal shell which is press-fitted in the human pelvic bone, the general trend towards a smaller wall thickness yielding an increased compliance can be observed with larger bearing diameters. This may lead to deformations of the metal shell making it difficult for the surgeon to properly introduce the insert. Hence, taking into account that a proper seating of the insert is absolutely necessary when using a ceramic insert in order to avoid point loads, operation time may strongly increase especially when minimal invasive surgery technique is used. With decreasing overall wall thickness of the acetabular components the volumetric stresses increase by definition. Therefore, an optimal component coupling between insert and metal shell is necessary in order to avoid point loads and resulting stress concentrations. With pre-assembled systems, this optimal coupling is reached by the force-controlled insertion of the insert in the metal shell without any prior deformation of the shell. This procedure enables to design acetabular components with a much lower overall wall thickness than conventional systems. As an example, in the case of the DELTA motion system, this overall wall thickness has been decreased to 5 mm allowing e.g. for a usage of a 36 mm bearing couple together with a 46 mm outer diameter of the metal shell. Additionally, the coating of the metal shell allows for direct bone ingrowth. Problems involved with larger bearing diameters may also arise from higher wear rates inducing possibly osteolysis and aseptic loosening. Investigations concerning the wear behaviour of large ceramic bearings have shown that there is no increase in the wear volume with increasing diameter.

The problem of modular acetabular cups in total hip replacement (THR) links with its survival, unpredictable because of wear and fixation. In fact, while primary fixation is not a problem, the use of screws could generate bone resorption. A monoblock cup made by tantalum and polyethylene insert is available since some years. Tantalum is a metal element with an elasticity intermediate between cortical and trabecular bone, a three times higher porosity than titanium and a very high ductility. These features allow a very high primary and secondary stability eliminating movements between insert and metal. From 2001 we started using the TMT cup and we performed 48 implants in 45 patients: 18 male and 30 female. The mean age was 64 years old.. 80% of the patients were affected of primary arthritis, 20% avascular head necrosis and fracture. In last 20 procedures we perform a minimal invasive approach (around 9 cm.). The mean follow up was 26 months. We reported no infections, no loosening and 1 traumatic dislocation. Follow up showed good stability on the acetabular side. In conclusion we can affirm that, despite our preliminary results, the tantalum cup could open new perspectives in primary hip replacements

Aims

This study reports the mid-term results of total hip arthroplasty (THA) performed using a monoblock acetabular component with a large-diameter head (LDH) ceramic-on-ceramic (CoC) bearing.

Aims. Limited implant survival due to aseptic cup loosening is most commonly responsible for revision total hip arthroplasty (THA). Advances in implant designs and materials have been crucial in addressing those challenges. Vitamin E-infused highly cross-linked polyethylene (VEPE) promises strong wear resistance, high oxidative stability, and superior mechanical strength. Although VEPE monoblock cups have shown good mid-term performance and excellent wear patterns, long-term results remain unclear. This study evaluated migration and wear patterns and clinical and radiological outcomes at a minimum of ten years’ follow-up. Methods. This prospective observational study investigated 101 cases of primary THA over a mean duration of 129 months (120 to 149). At last follow-up, 57 cases with complete clinical and radiological outcomes were evaluated. In all cases, the acetabular component comprised an uncemented titanium particle-coated VEPE monoblock cup. Patients were assessed clinically and radiologically using the Harris Hip Score, visual analogue scale (pain and satisfaction), and an anteroposterior radiograph. Cup migration and polyethylene wear were measured using Einzel-Bild-Röntgen-Analyze software. All complications and associated treatments were documented until final follow-up. Results. Clinical assessment showed persistent major improvement in all scores. On radiological assessment, only one case showed a lucent line (without symptoms). At last follow-up, wear and migration were below the critical thresholds. No cup-related revisions were needed, indicating an outstanding survival rate of 100%. Conclusion. Isoelastic VEPE cups offer high success rates and may prevent osteolysis, aseptic loosening, and the need for revision surgeries in the long term. However, longer follow-up is needed to validate our findings and confirm the advantages offered by this cup. Cite this article: Bone Jt Open 2024;5(10):825–831

The use of cementless acetabular components is currently the gold standard for treatment in total hip arthroplasty (THA). Porous coated cups have a low modulus of elasticity that enhances press-fit and a surface that promotes osseointegration. Monoblock acetabular cups represent a subtype of uncemented cup with the liner moulded into the metal shell, minimizing potential backside wear and eliminating the chance of mal-seating. The aim of this study was to compare the short-term clinical and radiographic performances of a modular cup with that of a monoblock cup, with particular interest in the advent of lucent lines and their correlation with clinical outcomes. In this multi-surgeon, prospective, randomized, controlled trial, 86 patients undergoing unilateral THA were recruited. Participants were randomized to either a porous-coated, modular metal-on-polyethylene (MoP) acetabular component (n=46) or a hydroxyapatite (HA)- and titanium-coated monoblock shell with ceramic-on-ceramic (CoC) bearing (n=42). The porous-coated cup had an average pore size of 250 microns with an average volume porosity of 45%, whereas the monoblock shell had an average pore size of 300 microns with an average volume porosity of 48% and a HA coating thickness of 80 nm. There were no baseline demographic differences between both groups regarding sex, age, body mass index (BMI), or American Society of Anaesthesia (ASA) class (p>0.05). All of the sockets were under-reamed by 1 mm. Radiographs and patient-reported outcome measures (PROMs), including modified Harris Hip Score (mHHS), Western Ontario and McMaster Universities Arthritis Index (WOMAC) and University of California at Los Angeles (UCLA) Hip Score, were available for evaluation at a minimum of 2 years of follow-up. A radiolucent distance between the cup and acetabulum of ≥0.5 mm was defined as gap if it was diagnosed from outset or as radiolucency if it had sclerotic edges and was found on progressive x-ray analyses. Thirty-two gaps (69%) were found in the modular cup group and 28 (6%) in the monoblock one (p=0.001). Of the former, 17 filled the gaps whereas 15 turned into a radiolucency at final assessment. Of the latter, only 1 of the gaps turned into a radiolucency at final follow-up (p 0.05) in both groups. Only the porous-coated cup was an independent predictor of lucent lines (OR:0.052, p=0.007). No case underwent revision surgery due to acetabular loosening during the study period. Only 2 cases of squeaking were reported in the CoC monoblock shell. Both porous-coated modular and hydroxyapatite-coated monoblock cups showed successful clinical results at short-term follow-up, however, the former evidenced a significantly higher rate of radiolucent line occurrence, without any association with PROMs. Since these lines indicate the possibility of future cup loosening, longer follow-up and assessment are necessary

Porous tantalum is a highly osteoinductive biomaterial, initially introduced in orthopedics in 1997, with a subsequent rapid evolution of orthopedic applications. The use of porous tantalum for the acetabular component in primary total hip arthroplasty (THA) has demonstrated excellent short-term and mid-term results. However, long term data are scarce. The purpose of this prospective study is to report the long-term clinical and radiological outcome following use of an uncemented porous tantalum acetabular component in primary THA with a minimum follow-up of 17.5 years, in a previously studied cohort of patients. We prospectively followed 128 consecutive primary THAs in 140 patients, between November 1997 and June 1999. A press-fit porous tantalum monoblock acetabular component was used in all cases. The presence of initial gaps in the polar region, as sign of incomplete seating of the monoblock cup, was assessed on the immediate postoperative radiographs. All patients were followed clinically and radiographically at 6, 12, and 24 weeks and 12 months and then at 2, 5, 8, 10, and 19 years, for a mean of 18.1 years (range 17.5 – 19 years). Periacetabular dome gap filling, acetabular cup migration and polyethylene wear were assessed by the EBRA digital measurement system, until 2 years postoperatively. Mean age of patients at the time of operation was 60.4 years old (range 24 – 72). Harris hip score, Oxford Hip Score and range of motion (ROM) were dramatically improved in all cases (p < 0.001). In the initial postoperative radiographs, periacetabular dome gaps were observed in the 15% of cases, and were progressively filled within 6 months. In 2 years postoperatively, the mean component migration, as shown in EBRA study, was 0.67 mm. At last follow-up, all cups were radiographically stable with no evidence of migration, gross polyethylene wear, progressive radiolucencies, osteolytic lesions or acetabular fractures. The survivorship with re-operation for any reason as end point was 92.8%, whereas the survivorship for aseptic loosening as an end point was 100%. Upon visual inspection, two removed acetabular components due to recurrent dislocation and infection, respectively, showed extensive bone osseointegration. In our primary THA series, the porous tantalum monoblock cup demonstrated excellent clinical and radiographic outcomes with no failures because of aseptic loosening at a mean follow-up of 18.1 years. Porous tantalum acetabular components showed excellent initial stability, produced less wear debris and revealed a great potential for bone ingrowth. Due to its unique osteoinductive properties and elliptical shape, porous tantalum monoblock cups have demonstrated superior short and long-term survivorship compared to other press fit prostheses in the market

There has been a longstanding need for a structural biomaterial that can serve as a bone graft substitute or implant construct and is effective for fixation by bone ingrowth. A porous tantalum material was developed to address these issues. The purpose of this paper and presnetation is to describe the properties and 2 to 5 year clinical results of porous tantalum in various reconstructive orthopaedic procedures. Porous tantalum has been used to manufacture primary and revision acetabular cups, acetabular augments, tibial and patella implants, patellar augments, structural devices for the treatment of osteonecrosis, and spinal fusion implants. Clinical follow-up includes: 2–5 year clinical and radiographic evaluation of: 414 monoblock cups in primary THA, 36 monoblock cups and 587 revision hemispheres used in revision THR, 16 hips revised with acetabular augments and revision hemispheres; 2 to 4 years for 101 tibial implants used in primary TKR and 69 patellas used in cementless TKR; 2–4 years for 11 patellar augments in salvage TKR, 1–5 years for 53 revision TKRs using knee spacers; 1–4 years for 91 osteone-crosis hip implants; and for 15 cervical fusion cases. This innovative tantalum implant material with trabecular architecture possesses advantages in stiffness, friction coefficient, porosity, rate and extent of tissue ingrowth, and versatility in manufacturing of structural devices. It has been clinically validated in numerous and diverse reconstructive procedures

Press-fit acetabular reconstructions have become the standard THA; however, controversies remain. The purpose of this study was to critically evaluate serial radiographs for initial cup stability, i.e. gaps and signs of periacetabular interface changes for a porous tantalum monoblock socket. A multicenter study evaluating 574 primary THRs (542 patients) performed by 9 surgeons at 7 hospitals, all with a monoblock cup without screws. Analyses included clinical outcomes and detailed 2-year minimum radiographic evaluation by one independent observer (mean follow-up, 33 months). Complications included 9 intra-operative acetabular fractures. Among the 123 cases excluded from radiographic evaluations: deceased (19), lost-to-follow-up (8), 7 early revisions (recurrent dislocations (6) and one trauma-related loosening), and sepsis (3). Patient demographics (414 hips): mean age 65 years (19–93); 58 percent females. Baseline radiographs revealed 113 zones in 85 hips (21 percent) with acetabular gaps; 36 in zone I, 72 in zone II, and 5 in zone III. Of these radiolucencies, 57 zones were 1 mm or less and 56 zones ranged from 2 to 5 mm. At last follow-up, 64 hips (75 percent) had complete gap fill-in, including 100 percent of gaps greater than 3 mm. There were no socket migrations, no evidence of lysis, no revisions for loosening, and no complete periacetabular interface radiolucencies. The fill-in of preexisting OA cysts and gaps is attributed to adequate initial stability and osteointegration into the porous tantalum. These results suggest that a monoblock cup without screws is an attractive option in THA

Introduction: Tantalum Monoblock Acetabular cup was designed to reduce backside wear and stimulate osseo-integration of cup with bone. The cup has peripheral fit to improve the initial stability and further stability and longevity depends on the osseointegration of cup with acetabulum. The revision cup was intended to give added stability with screws in case of defective rim or large acetabulum. The aim of this study is to assess the radiological outcome following tantalum monoblock revision cup in total hip replacement. Methods: Between 1999 and 2000, 32 Tantalum mono-block revision acetabular cups was used in 31 patients. Standard hip radiographs were performed during post op, at three months, six months and then annually. X rays were assessed for loosening in De Lee and Charnley zones and for migration of cup. Results: At a minimum follow-up of 2 years (range 2 to 5 years), 31 hips in 30 patients were assessed. The average age of the patient was 62.4 years (39–78 years). Three Brookers type 1 and one type 2 heterotrophic ossification was seen. There was a gap of 2–5mm in Zone 1(6 patients), 1–5mm in Zone 2 (8 Patients) and 5mm in Zone 3 of one patient. At final follow up, all the gaps were filled, except for one, where 5mm gap was persistent. There was no migration of cup or problems with screws. All the patients were satisfied with the operation. Conclusion: Short term radiological result following uncemented revision tantalum monoblock acetabular cup in total hip replacement is highly encouraging. However, similar results from other centres and long term follow up studies are necessary to confirm the efficacy of the revision cups

It is accepted that larger diameter heads are more difficult to dislocate due to the increased distance the head has to travel to come out of the cup. Currently larger femoral heads are being used for their resistance to dislocation however, there remains little reporting on the effect of design of cup on jump distance. Monoblock metal on metal cups, which were designed for hip resurfacing are typically less than a hemisphere internally in order to increase the range of motion (ROM) needed when the femoral neck is retained. This does however also reduce the jump distance. We investigated several designs of cup with a variety of head sizes in order to compare ROM using a computer range of motion tool and a two dimensional jump distance with the cup at 45 degrees inclination. Jump distances were calculated for: Internally hemispheric cups in 28, 32 and 36mm bearing diameters; 28, 40 and 44mm polyethylene liners which were hemispheric but with an additional 2mm cylinder and a 0.7mm chamfer at the equator (Trident, Stryker, Mahwah, USA); 38, 48 and 54mm monoblock metal on metal resurfacing cups with a 3.5mm offset (BHR, Smith and Nephew, Memphis, USA); 40, 48, 58 dual mobility cups with an anatomic rim (Restoration ADM, Stryker, Mahwah, USA). Range of motion modeling was carried out using custom-written software according to a previously published method2 with 5 degrees of pelvic tilt and a standard femoral component. For the present study, range of motion was assessed on a standard stem with a 132° neck angle. Inclination of the cup was set to 45° and anteversion to 20°. For each implant tested, the total ROM was computed in flexion/extension, ab/adduction, and int/external rotation. Components tested for range of motion were: Trident 32, 36, 40 and 44mm Internal Diameter; Hemispheric 28 and 32mm Internal Diameter cups; MITCH TRH MoM Monoblock Resurfacing Cup (Stryker EMEA, Montreux, Switzerland) 46mm cup bearing diameter with a 2.75mm offset bore; Dual Mobility 40, 46 and 58mm cups. The metal on metal monoblock cups had a very high range of motion but a 48mm head has only a similar jump distance to a hemispheric 36mm design. The designs with the cylinder and chamfer have a markedly higher jump distance than their hemispheric equivalents but slightly reduced ROM. Interestingly, the dual mobility design has almost double the jump distance of an equivalently sized metal on metal resurfacing type cup and a higher jump distance than an equivalent head size in a conventional unipolar design. The dual mobility design has similar ROM to a 40mm head in the hemisphere with cylinder and chamfer design. ROM is slightly higher in the hemispheric and sub-hemispheric designs but this model does not take into account bony or soft tissue impingement. The role of design of ace-tabular component has a great effect on the range of motion and jump distance of bearings

Originally introduced in 1997, porous tantalum is an attractive alternative metal for orthopaedic implants because of its unique mechanical properties. Porous tantalum has been used in numerous types of orthopaedic implants, including acetabular cups in total hip arthroplasty. The early clinical results from porous tantalum acetabular cups have been promising. The purpose of this study was to evaluate the presence of bone ingrowth and the incidence of osteolytic lesions in the acetabular cup -at 10 year follow up – in patients who had a total hip arthroplasty with a monoblock porous tantalum acetabular cup. 50 consecutive patients underwent a total hip arthroplasty with a monoblock porous tantalum acetabular component. All patients had computed tomography at an average of 10 years of follow-up. The computed tomography scan used a standard, validated protocol to evaluate bony ingrowth in the cup and for the presence of osteolysis. The computed tomographic scans showed evidence of extensive bony ingrowth, and no evidence of osteolysis. This study reports the 10-year results of a monoblock porous tantalum acetabular cup. This is the first study to evaluate a porous tantalum acetabular cup with the use of computed tomography. These results show that a porous tantalum monoblock cup has excellent bony ingrowth and no evidence osteolysis at 10 year follow-up. These results suggest that porous tantalum is an attractive material for implantation in young, active patients

Introduction. The aim of this study is to report the results of Revision hip arthroplasty using large diameter, metal on metal bearing implants- minimum 2 year follow up. Methods. A single centre retrospective study was performed of 22 consecutive patients who underwent acetabular revision surgery using metal on metal bearing implants between 2004 and 2007. Birmingham hip resurfacing (BHR) cup was used in all patients - monoblock, uncemented, without additional screws in 16 cases and cemented within reinforcement or reconstruction ring in 6 cases. Femoral revisions were carried out as necessary. Results. There were 16 men and 6 women with a mean age of 71 years (51-83). Revision surgery was performed for aseptic loosening in 10, infected primary hip arthroplasty in 8, infected Hemiarthroplasty in 1 and Peri-prosthetic fracture with loosening in 3 patients. A 2-stage revision was performed for all infected hips. One patient died and the remaining 21 patients had clinical and radiological assessment at a mean 35 months (24-60). The mean Harris hip score was 75 (23-98) with 50% good to excellent results. Only 1 patient had further revision to a proximal femoral replacement and constrained cup in 2 stages for recurrent infection at 24 months. There were 2 recurrent infections (both revised for septic loosening) and 1 non-union of trochanteric osteotomy. There were no dislocations in the group. No radiological loosening of implants or metal ion complications have been seen at last follow up. Conclusions. We believe this is the first reported series on the use of large diameter metal on metal bearing surfaces for revision hip arthroplasty. Our series shows satisfactory short to medium term results in this complex group of patients with no component loosenings, despite monoblock cups and no dislocations

Modern prosthetic stem construction strives to achieve the attractive goals of stress shielding prevention and optimal osteointegration. PhysioLogic stem is a new generation composite isoelastic femoral stem consisting of titanium core sheathed in implantable PEEK polymer and coated with titanium layer. This construction combines the benefits of both stress shielding prevention, due to its elasticity under bending load corresponding closely to that of natural bone, and rapid osteointegration, due to the stem's titanium coating. The aim of this study is long-term clinical progress evaluation and retrospective analysis in patients undergoing primary PhysioLogic stem implantation at our institution. From 1998 to 2003, we performed 51 primary total hip arthroplasty (THA) operations with implantation of PhysioLogic Stem at our institution. Indications for THA included osteoarthritis (21), hip dysplasia (14), rheumatoid arthritis (10), and femoral neck nonunion (6). In all patients we used totally uncemented system — PhysioLogic Stem and monoblock cup with different types of bearing surface articulation (40 metal/polyethylene, 3 ceramic/polyethylene, and 8 metal/metal). In all cases head size was 28mm. Two patients died in the early post-op period at day 1 and day 9 from disseminated intravascular coagulation and pulmonary embolism, respectively, and were excluded from subsequent analysis. Analyzed patients included 20 women and 29 men; median age 45, range 21–69. Post-operatively, the patients were evaluated at 3 and 6 months, 1 year, and yearly thereafter. Median follow-up period was 14 years, range 11 to 16 years. Clinical and functional outcomes were evaluated by Harris Hip Score. Bone density in Gruen's and Charnley's zones was measured by dual-energy x-ray absorptiometry. Four patients died at 5–8 years postoperatively from cardiac causes. Two patients underwent revision surgery: one patient underwent “dry revision” due to hip dislocation with exchange for longer head while keeping the original PhysioLogic stem in place; second patient underwent stem removal after chronic periprosthetic infection. Among the 45 patients with surviving PhysioLogic Stem, 33 patients (75%) underwent subsequent contralateral total hip arthroplasty with standard uncemented stems types Spotorno or Zweymuller. These patients were surveyed at postoperative evaluation about subjective comparative performance of PhysioLogic Stem versus standard stem. Twenty seven patients (82%) reported the PhysioLogic stem to be equivalent or superior to the standard stem, with 15 patients (45%) rating the PhysioLogic stem as subjectively more comfortable than the standard stem. The average Harris hip score improved from 40 points preoperatively (range 27 to 48) to 93 points (range 89 to 95) at the time of final follow-up. All stems continue to show adequate bone-ingrown fixation with no radiological signs of aseptic loosening to date. The PhysioLogic stem removed in the aforementioned case of chronic periprosthetic infection also showed clear signs of good osteointegration. Our study showed that the PhysioLogic stem implantation resulted in favorable clinical and functional performance at long-term follow-up, making it an attractive alternative to standard stems

Tantalum is a pure metallic element and is attractive for use in orthopaedic implants because it is one of the most biocompatible metals available for implant fabrication. The potential advantages for the use of porous tantalum in total hip arthroplasty include:. excellent bone and tissue ingrowth observed histologically;. direct polyethylene intrusion into the metal substrate. This allows the elimination of any potential backside wear in the monoblock cup;. The two-piece design consist of a tantalum shell with screw holes for fixation into the dome of the ilium and posterior column. A polyethylene liner is cemented into the tantalum shell to eliminates backside motion. In addition, acetabular augments of porous tantalum have been developed for use in restoration of major bone deficiencies. Prospective study on a case serie of 113 THA’s performed by two surgeons in a single institution. From 2000 to December 2003, 113 hips have undergone arthroplasty using porous tantalum implants consisting of 54 primary hip arthroplasties and 59 revision THA’s. The patients where evaluated clinical and radiographically every 3 month during the first year, and after yearly. Mean patient age was 64,2 years, (range 44–87); with 59% males and 41% females. No patients died or lost to follow-up. No further surgeries of the involved hip. No radiographic signs of loosening of the acetabular component according to the criteria of Hodgkinson et al. No problems specifically from the use of acetabular augments or extra screws has been noted. Of the revision series, a total of 16 cases have received acetabular augments. Complications included 1 superficial infection, 2 dislocations. No vasculonervous complication; and in 2 cases technical difficulties to achieve good fixation due to ethiology of the THA (desarthrodesis). The average Harris hip score improved from 48 to 89 following primary surgery. Tantalum acetabular components for primary and revision hip surgery have performed well for up to 3 years, and have excellent stability. The two-piece acetabular shell and augments permits the reconstruction of every acetabular bone defect

Tantalum is a pure metallic element and is attractive for use in orthopaedic implants because it is one of the most biocompatible metals available for implant fabrication. The potential advantages for the use of porous tantalum in total hip arthroplasty include:. excellent bone and tissue in growth observed histologically;. direct polyethylene intrusion into the metal substrate. This allows the elimination of any potential backside wear in the monoblock cup;. The two-piece design consist of a tantalum shell with screw holes for fixation into the dome of the ilium and posterior column. A polyethylene liner is cemented into the tantalum shell to eliminates backside motion. In addition, acetabular augments of porous tantalum have been developed for use in restoration of major bone deficiencies. Prospective study on a case serie of 113 THA’s performed by two surgeons in a single institution. From 2000 to December 2003, 113 hips have undergone arthroplasty using porous tantalum implants consisting of 54 primary hip arthroplasties and 59 revision THA’s. The patients where evaluated clinical and radiographically every 3 month during the first year, and after yearly. Mean patient age was 64,2 years, (range 44–87); with 59% males and 41% females. No patients died or lost to follow-up. No further surgeries of the involved hip. No radiographic signs of loosening of the acetabular component according to the criteria of Hodgkinson et al. No problems specifically from the use of acetabular augments or extra screws has been noted. Of the revision series, a total of 16 cases have received acetabular augments. Complications included 1 superficial infection, 2 dislocations. No vasculo-nervous complication; and in 2 cases technical difficulties to achieve good fixation due to ethiology of the THA (desarthrodesis). The average Harris hip score improved from 48 to 89 following primary surgery. Tantalum acetabular components for primary and revision hip surgery have performed well for up to 3 years, and have excellent stability. The two-piece acetabular shell and augments permits the reconstruction of every acetabular bone defect

Pure tantalum has been proposed in orthopaedic surgery. Its chemical and physical properties have been widely studied in the past. From pure tantalum is obtained a spongy structure (Trabecular Metal Technology: TMT) that shows a full thickness porosity which is 2–3 times higher compared to other surfaces available for bone ingrowth with a three-dimensional porous arrangement in rough trabeculae. Pores (average diameter of 650 mm) are fully interconnected and represent 75–80% of the whole volume. TMT acetabular components have an elliptical shape and have an irregular external surface which both allow an optimal mechanical fit. We retrospectively reviewed 212 cases of monoblock porous tantalum acetabular cup (Hedrocel, Stratec) implanted between 1999 and 2003 in a single centre with a minimum follow-up of 9–10 years; There were 98 men and 114 women, with an average age of 65 years. They all underwent primary or revision total hip arthroplasty or to acetabular component revision alone. In all patients a monoblock porous tantalum acetabular component with polyethylene directly compression molded into cup, with or without peripheral holes for screws, was implanted. In all primary procedures the same femoral stem (Synergy, Smith and Nephew) was implanted. All patients were evaluated with a clinical examination (Harris Hip Score: HHS) and with standard radiographs of the pelvis preoperatively and 1, 3, 6 months and yearly postoperatively. The stability of the acetabular cup was determined by modified Engh's criteria. The HHS score improved from 42 preoperatively to 94 after one year; at 13 years follow-up it was 95. The subjective outcome was widely satisfying, with the majority of patients experimenting good functional recovery and return to daily activities. Osteointegration of the acetabular component was present in all X-rays controls at one year after surgery. All post-operative evidence of residual bone loss (geodes, bone defects in revisions and in displasia) were no more radiographically evident after 1 year postoperatively as the host bone quickly filled these gaps. We did not observe osteolysis nor progressive radiolucent lines at the latest follow-up. None of the cups was revised, except 3 cases, revised for infection. Both clinical and radiographic results are the same or even superior to those of coated implants. Our experience confirms that trabecular metal tantalum cups can avoid the formation of bone-implant interface membrane and consequently can avoid implant loosening. The most important advantages of TMT monoblock cups are: no potential for polyethylene backside wear, prevention of loosening and osteolysis, increased early fixation via friction, improved late biological stability, maximum bone-implant contact. High biocompatibility of porous tantalum and its elastic modulus very close to bone influence positively earlier and wider osteointegration of the implant. Larger series are needed to confirm the positive our preliminary results