Aims

The aim of this study was to compare the biomechanical models of two frequently used techniques for reconstructing severe acetabular defects with pelvic discontinuity in revision total hip arthroplasty (THA) – the Trabecular Metal Acetabular Revision System (TMARS) and custom triflange acetabular components (CTACs) – using virtual modelling.

First-time revision acetabular components have a 36% re-revision rate at 10 years in Australia, with subsequent revisions known to have even worse results. Acetabular component migration >1mm at two years following revision THA is a surrogate for long term loosening. This study aimed to measure the migration of porous tantalum components used at revision surgery and investigate the effect of achieving press-fit and/or three-point fixation within acetabular bone. Between May 2011 and March 2018, 55 patients (56 hips; 30 female, 25 male) underwent acetabular revision THR with a porous tantalum component, with a post-operative CT scan to assess implant to host bone contact achieved and Radiostereometric Analysis (RSA) examinations on day 2, 3 months, 1 and 2 years. A porous tantalum component was used because the defects treated (Paprosky IIa:IIb:IIc:IIIa:IIIb; 2:6:8:22:18; 13 with pelvic discontinuity) were either deemed too large or in a position preventing screw fixation of an implant with low coefficient of friction. Press-fit and three-point fixation of the implant was assessed intra-operatively and on postoperative imaging. Three-point acetabular fixation was achieved in 51 hips (92%), 34 (62%) of which were press-fit. The mean implant to host bone contact achieved was 36% (range 9-71%). The majority (52/56, 93%) of components demonstrated acceptable early stability. Four components migrated >1mm proximally at two years (1.1, 3.2, 3.6 and 16.4mm). Three of these were in hips with Paprosky IIIB defects, including 2 with pelvic discontinuity. Neither press-fit nor three-point fixation was achieved for these three components and the cup to host bone contact achieved was low (30, 32 and 59%). The majority of porous tantalum components had acceptable stability at two years following revision surgery despite treating large acetabular defects and poor bone quality. Components without press-fit or three-point fixation were associated with unacceptable amounts of early migration

Aims. Reconstruction of the acetabulum after failed total hip arthroplasty (THA) can be a surgical challenge in the presence of severe bone loss. We report the long-term survival of a porous tantalum revision acetabular component, its radiological appearance and quality of life outcomes. Patients and Methods. We reviewed the results of 46 patients who had undergone revision of a failed acetabular component with a Paprosky II or III bone defect and reconstruction with a hemispherical, tantalum acetabular component, supplementary screws and a cemented polyethylene liner. Results. After a minimum follow-up of ten years (ten to 12), the survivorship of the porous tantalum acetabular component was 96%, with further revision of the acetabular component as the end point. The ten-year survivorship, with hip revision for any reason as the end point, was 92%. We noted excellent pain relief (mean Western Ontario and McMaster Universities Arthritis Index (WOMAC) score pain 92.6, (40 to 100)) and good functional outcomes (mean WOMAC function 90.3 (30.9 to 100), mean University of California Los Angeles activity scale 5 (2 to 10)) and generic quality of life measures (mean Short Form-12 (SF-12) physical component 48.3 (18.1 to 56.8), mean SF-12 mental component 56.7 (32.9 to 70.3)). Patient satisfaction with pain relief, function and return to recreational activities were excellent. Take home message: Uncemented acetabular reconstruction using a tantalum acetabular component gives excellent clinical and quality of life outcomes at a minimum follow-up of ten years. Cite this article: Bone Joint J 2016;98-B:767–71

Glenoid failure remains the most common mode of total shoulder arthroplasty failures. Porous tantalum metal (Trabecular Metal™, Zimmer) have grown in popularity in hip and knee arthroplasty. First-generation porous tantalum metal-backed glenoid components demonstrated metal debris, resulted in failure, and were revised to second-generation glenoid implants. Evidence for second-generation porous tantalum metal implants in shoulder arthroplasty is sparse.1–4 The purpose of this study was to assess clinical and radiographic outcomes in a series of patients with second-generation porous tantalum glenoid components at a minimum two-years postoperative. We retrospectively reviewed the clinical and radiographic outcomes of patients who received a second-generation porous tantalum glenoid component anatomic shoulder arthroplasty between May 2009 and December 2017 with minimum 24 months follow-up. The shoulder arthroplasties were performed by one of two senior fellowship-trained surgeons. We collected postoperative clinical outcome indicators: EQ5D visual analog scale (VAS), Western Ontario Osteoarthritis of the Shoulder (WOOS) Index, American Shoulder and Elbow Surgeons (ASES) Score, and Constant Score (CS). Radiographic review was performed by an independent fellowship-trained surgeon. The Endrizzi metal debris grading system1 was utilized to grade metal debris. We computed descriptive statistics and compared outcome scores between groups via the non-parametric Wilcoxon rank-sum test, with group-wise comparisons defined by: metal debris and humeral head migration (secondary analyses). Thirty-five patients [23 male (65.7%) and 12 female (34.3%)] with 40 shoulder replacements participated in the study. Forty of 61 shoulders (65.6%) had an average of 64 ± 20.3 months follow-up (range 31 to 95). Average BMI was 27.5 ± 4.4 kg/m2 (range 19.5 to 39.1). The average postoperative EQ5D VAS at final follow-up was 74.6 ± 22.5, WOOS Index 87.9 ± 16.6, ASES Score 88.3 ± 10.9, and CS 80.4 ± 13. At final follow-up, 18 of 40 shoulders (45%) had metal debris [15 of 40 (37.5%) Endrizzi grade 1 and three of 40 (7.5%) Endrizzi grade 2], and 22 of 40 shoulders (55%) did not show evidence of metal debris. There was one non-revision reoperation (open subscapularis exploration), one shoulder with anterosuperior escape, three shoulders with glenoid radiolucencies indicative of possible glenoid loosening, and nine shoulders with superior migration of the humeral head (>2mm migration at final follow-up compared to immediate postoperative). When comparing postoperative scores between patients with vs without metal debris, we found no statistically significant difference in the EQ5D VAS, WOOS Index, ASES Score and CS. On further analyses, when comparing superior migration of the humeral head and postoperative outcomes scores, we found no statistically significant difference. We report the longest published follow-up with clinical and radiographic outcomes of second-generation porous tantalum glenoid anatomic shoulder arthroplasties. In this series of patients, 45% of total shoulder arthroplasties with a second-generation porous tantalum glenoid implant had radiographic evidence of metal debris. This metal debris was not statistically associated with poorer postoperative outcomes. Further investigation and ongoing follow-up are warranted

First-time revision acetabular components have a 36% re-revision rate at 10 years in Australia, with subsequent revisions known to have even worse results. Acetabular component migration >1mm at two years following revision THA is a surrogate for long term loosening. This study aimed to measure the migration of porous tantalum components used at revision surgery and investigate the effect of achieving press-fit and/or three-point fixation within acetabular bone. Between May 2011 and March 2018, 55 patients (56 hips; 30 female, 25 male) underwent acetabular revision THR with a porous tantalum component, with a post-operative CT scan to assess implant to host bone contact achieved and Radiostereometric Analysis (RSA) examinations on day 2, 3 months, 1 and 2 years. A porous tantalum component was used because the defects treated (Paprosky IIa:IIb:IIc:IIIa:IIIb; 2:6:8:22:18; 13 with pelvic discontinuity) were either deemed too large or in a position preventing screw fixation of an implant with low coefficient of friction. Press-fit and three-point fixation of the implant was assessed intra-operatively and on postoperative imaging. Three-point acetabular fixation was achieved in 51 hips (92%), 34 (62%) of which were press-fit. The mean implant to host bone contact achieved was 36% (range 9–71%). The majority (52/56, 93%) of components demonstrated acceptable early stability. Four components migrated >1mm proximally at two years (1.1, 3.2, 3.6 and 16.4mm). Three of these were in hips with Paprosky IIIB defects, including 2 with pelvic discontinuity. Neither press-fit nor three-point fixation was achieved for these three components and the cup to host bone contact achieved was low (30, 32 and 59%). The majority of porous tantalum components had acceptable stability at two years following revision surgery despite treating large acetabular defects and poor bone quality. Components without press-fit or three-point fixation were associated with unacceptable amounts of early migration

Introduction. Achieving durable implant–host bone fixation is the major challenge in uncemented revision hip arthroplasty when significant bone stock deficiencies are encountered. The purpose of this study was to develop an experimental model which would simulate the clinical revision hip scenario and to determine the effects of alendronate coating on porous tantalum on gap filling and bone ingrowth in the experimental model. Methods. Thirty-six porous tantalum plugs were implanted into the distal femur, bilaterally of 18 rabbits for four weeks. There were 3 groups of plugs inserted; control groups of porous tantalum plugs (Ta) with no coating, a 2nd control group of porous tantalum plugs with micro-porous calcium phosphate coating, (Ta-CaP) and porous tantalum plugs coated with alendronate (Ta-CaP-ALN). Subcutaneous fluorochrome labelling was used to track new bone formation. Bone formation was analysed by backscattered electron microscopy and fluorescence microscopy on undecalcified histological sections. Results. The relative increase in mean volume of gap filling, bone ingrowth and total bone formation was 124%, 232% and 170% respectively in Ta-CaP-ALN compared with the uncoated porous tantalum (Ta) controls, which was statistically significant. The contact length of new bone formation on porous tantalum implants in Ta-CaP-ALN was increased by 700% (8-fold) on average compared with the uncoated porous tantalum (Ta) controls. Discussion. Alendronate coated porous tantalum significantly modulated implant bioactivity compared with controls. This study has demonstrated the significant enhancement of bone-implant gap filling and bone ingrowth, which can be achieved by coating porous tantalum with alendronate. It is proposed that, when faced with the clinical problem of revision joint replacement in the face of bone loss, the addition of alendronate as a surface coating would enhance biological fixation of the implant and promote the healing of bone defects

Introduction: Achieving durable implant–host bone fixation is the major challenge in uncemented revision hip arthroplasty when significant bone stock deficiencies are encountered. The purpose of this study was. to develop an experimental model which would simulate the clinical revision hip scenario and. determine the effects of alendronate coating on porous tantalum on gap filling and bone ingrowth in the experimental model. Methods: Thirty-six porous tantalum plugs were implanted into the distal femur, bilaterally of 18 rabbits for four weeks. There were 3 groups of plugs inserted; control groups of porous tantalum plugs (Ta) with no coating, a 2nd control group of porous tantalum plugs with micro-porous calcium phosphate coating, (Ta-CaP) and porous tantalum plugs coated with alendronate (Ta-CaP-ALN). Subcutaneous fluorochrome labelling was used to track new bone formation. Bone formation was analysed by backscattered electron microscopy and fluorescence microscopy on undecalcified histological sections. Results: The relative increase in mean volume of gap filling, bone ingrowth and total bone formation was 124 %, 232 % and 170 % respectively in Ta-CaP-ALN compared with the uncoated porous tantalum (Ta) controls, which was statistically significant. The contact length of new bone formation on porous tantalum implants in Ta-CaP-ALN was increased by 700% (8-fold) on average compared with the uncoated porous tantalum (Ta) controls. Discussion: Alendronate coated porous tantalum significantly modulated implant bioactivity compared with controls. This study has demonstrated the significant enhancement of bone-implant gap filling and bone ingrowth, which can be achieved by coating porous tantalum with alendronate. It is proposed that, when faced with the clinical problem of revision joint replacement in the face of bone loss, the addition of alendronate as a surface coating would enhance biological fixation of the implant and promote the healing of bone defects

Introduction: Achieving durable implant–host bone fixation is the major challenge in uncemented revision hip arthroplasty when significant bone stock deficiencies are encountered. The purpose of this study was 1) to develop an experimental model which would simulate the clinical revision hip scenario and 2) determine the effects of alendronate coating on porous tantalum on gap filling and bone ingrowth in the experimental model. Methods: Thirty-six porous tantalum plugs were implanted into the distal femur, bilaterally of 18 rabbits for four weeks. There were 3 groups of plugs inserted; control groups of porous tantalum plugs (Ta) with no coating, a 2. nd. control group of porous tantalum plugs with micro-porous calcium phosphate coating, (Ta-CaP) and porous tantalum plugs coated with alendronate (Ta-CaP-ALN). Subcutaneous fluorochrome labelling was used to track new bone formation. Bone formation was analysed by backscattered electron microscopy and fluorescence microscopy on undecalcified histological sections. Results: The relative increase in mean volume of gap filling, bone ingrowth and total bone formation was 124 %, 232 % and 170 % respectively in Ta-CaP-ALN compared with the uncoated porous tantalum (Ta) controls, which was statistically significant. The contact length of new bone formation on porous tantalum implants in Ta-CaP-ALN was increased by 700% (8-fold) on average compared with the uncoated porous tantalum (Ta) controls. Discussion: Alendronate coated porous tantalum significantly modulated implant bioactivity compared with controls. This study has demonstrated the significant enhancement of bone-implant gap filling and bone ingrowth, which can be achieved by coating porous tantalum with alendronate. It is proposed that, when faced with the clinical problem of revision joint replacement in the face of bone loss, the addition of alendronate as a surface coating would enhance biological fixation of the implant and promote the healing of bone defects

Aims. The use of a porous metal shell supported by two augments with the ‘footing’ technique is one solution to manage Paprosky IIIB acetabular defects in revision total hip arthroplasty. The aim of this study was to assess the medium-term implant survival and radiological and clinical outcomes of this technique. Methods. We undertook a retrospective, two-centre series of 39 hips in 39 patients (15 male, 24 female) treated with the ‘footing’ technique for Paprosky IIIB acetabular defects between 2007 and 2020. The median age at the time of surgery was 64.4 years (interquartile range (IQR) 54.4 to 71.0). The median follow-up was 3.9 years (IQR 3.1 to 7.0). Results. The cumulative medium-term survival of the acetabular construct was 89%. Two hips (5.1%) required further revision due to shell loosening, one hip (2.6%) due to shell dislocation, and one hip (2.6%) due to infection. The median Harris Hip Score improved significantly from 47 points (IQR 41.5 to 54.9) preoperatively to 80 points (IQR 73.5 to 88.6) at the latest follow-up (p < 0.001). Conclusion. The reconstruction of Paprosky IIIB acetabular defects with porous tantalum shells and two augments using the ‘footing’ technique showed excellent medium-term results. It is a viable option for treating these challenging defects. Cite this article: Bone Joint J 2024;106-B(5 Supple B):54–58

Purpose: Porous tantalum has been shown to be very effective in achieving bone ingrowth. However, in some circumstances, bone quality or quantity is insufficient to allow adequate bone ingrowth. We hypothesized that the addition of alendronate to porous tantalum would enhance the ability of porous tantalum to achieve bone ingrowth in these challenging situations, such as when a gap exists between the implant and bone. We evaluated the effect of alendronate coated porous tantalum on new bone formation in an animal model incorporating a gap between implant and bone. Method: Thirty-six cylindrical porous tantalum implants were bilaterally implanted into the distal femur of 18 rabbits for 4 weeks. There were 3 groups of implants inserted; a control group of porous tantalum with no coatings, porous tantalum with micro-porous calcium phosphate coating, and porous tantalum coated with micro-porous calcium phosphate and alendronate. Subcutaneous fluorescent labeling was used to track new bone formation. Bone formation was analyzed by backscattered electron microscopy and fluorescent microscopy on undecalcified samples. Results: The relative increase in mean volume of gap filling, bone ingrowth and total bone formation was 143% (p< 0.001), 259% (p< 0.001) and 193% (p< 0.001) respectively in the alendronate coated porous tantalum compared with the uncoated porous tantalum controls. The relative increase in the percentage of new bone-implant contact length was increased by 804% on average in the alendronate coated porous tantalum compared with the uncoated tantalum controls. Conclusion: This study demonstrated the significant enhancement of bone-implant gap filling and bone ingrowth which can be achieved by coating porous tantalum with alendronate. It is proposed that, when faced with the clinical problem of revision joint replacement in the face of bone loss (at the hip, knee or elsewhere), the addition of an alendronate-delivery surface coating would enhance biological fixation of the implant and promote the healing of bone defects

Purpose. Durable fixation may be difficult to achieve when significant bone loss is present, as it occurs in pelvic sarcoma resection and revision surgery of tumor implants. Purpose of this study was to review clinical results of primary and revision surgery of the pelvis and lower extremity in the setting of severe bone loss following limb salvage procedures for bone sarcoma using modular porous tantalum implants. Method. Retrospective study of 15 patients (nine females, six males) undergoing primary or revision pelvic reconstruction (five patients) or revision surgery of a tumor implant of the hip (five patients), knee (four patients), and ankle (one patient) using porous tantalum implants was undertaken. Reason for the tumor implant was resection of bone sarcoma in 13 cases and tumor-like massive bone loss in the remaining two cases. Cause for revision was aseptic failure (nine patients) or deep infection (six patients); average age at the time of surgery was 31 years (16–61 yrs). Revision was managed in a staged fashion in all the six infected cases. All patients presented severe combined segmental and cavitary bone defects. Bone loss was managed in all patients using porous tantalum implants as augmentation of residual bone stock and associated with a megaprosthesis in eight cases (five proximal femur, two distal femur, one proximal tibia). Average follow-up was 4.5 years for hip/knee implants and 2.5 yrs for pelvic reconstructions (range 1–6.8 yrs). Minimum follow-up of two years was available in 11 cases. Results. Infection recurred in one of the six cases managed for infection, requiring further treatment but allowing retention of the porous tantalum implant. All the patients showed well-fixed and functioning implants at latest follow-up. Conclusion. Porous tantalum has been very successful at early follow-up in patients with severe bone loss following primary and revision tumor-related surgery of the pelvis and lower extremity. Longer follow-up is required to appreciate long-term shortcomings

In this report, porous tantalum was used to achieve abductor tendon reattachment to structural allograft of the proximal femur in salvage reconstruction of a failed total hip arthroplasty. In each case, a porous tantalum segment with trapezoidal cross section was fixed to a dovetail joint of complementary geometry cut into the lateral greater trochanter. Fixation of the porous tantalum to the allograft was supplemented with polymethylmethacrylate cement. Residual abductors were mobilized from the surrounding soft tissues and secured against the porous tantalum segment with a short greater trochanteric reattachment device and cables. Patients were followed up at 73 and 80 months. Harris Hip Scores of 74 and 80 respectively were found. Both were unlimited community ambulators without support, had negative Trendelenberg signs, and were satisfied with the clinical outcomes. This preliminary experience suggests that porous tantalum has potential application in cases of severe proximal femoral bone loss involving abductor deficiency

Bone loss is a challenging reconstructive problem in revision total knee arthroplasty (TKA). Uncemented porous tantalum modular components are designed to act as substitutes for allograft bone in complex revision TKA with significant bone defects. A consecutive series of 23 revision TKAs performed by a single surgeon were reviewed at a minimum two-years following implantation. In all cases bone loss was assessed using the Anderson Orthopaedic Research Institute System, and porous tantalum components were used to augment the reconstructions when bone loss was encountered. Twenty-one patients had 23 procedures (2 bilateral) requiring the use of porous tantalum following 18 cases of aseptic loosening, 4 cases of staged re-implantation for infection, and 1 case of a periprosthetic patellar fracture and aseptic loosening. Structural bone graft was not used during this time period. Porous tantalum uses include: 20 distal and posterior femoral augments; 2 femoral cones; 8 patellar augments; and 18 tibial cones. 20 cases required augmentation in more than one area, and one case involved an extensor mechanism allograft. There were 2 cases of recurrent sepsis requiring removal of well-fixed tantalum components. At an average 37 months (24 to 73) no patients were lost to follow-up. Clinical follow-up in the remaining 21 cases showed reconstructions were functioning well with no revisions. Radiographic imaging showed re-establishment of the joint line, neutral mechanical axis, and signs of stable fixation of the augments. There were no cases of radiographic or clinical loosening at the most recent follow-up. Short term results with the use of porous tantalum augments and cones for bone loss in revision TKA demonstrate the versatile, and durable nature of these new reconstructive tools, at early follow-up

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

This paper reports the prospective 2 to 4 year clinical results of a porous tantalum monoblock tibia used in primary TKR, with comparison to a cemented modular tibial implant of the same articulating design. The subject tibial implant is relatively flexible design comprised of a porous tantalum base plate and direct compression molded polyethylene, with initial fixation achieved by press-fitting two porous tantalum posts. The porous tantalum implant was used without bone cement in 72 knees and with cement in 29 cases. The comparative tibial component was a cemented modular design with the same articulating surface. Clinical and radiographic data were collected prospectively, and consecutively, for 165 primary TKR cases implanted from 2000 – 2003. James Wood, Maurice Cates, Audley Mackel, Randall Morgan, Robert Poggie. The early clinical and radiographic results for the porous tantalum monoblock tibia (cemented and cementless) and the modular cemented implant were statistically the same. The preliminary evidence suggests that cementless application of this design is an attractive alternative for younger, more active patients

Introduction. A variety of porous coatings and substrates have been used to obtain fixation at the bone-implant interface. Clinical studies of porous tantalum, have shown radiographically well-fixed implants with limited cases of loosening. However, there has been limited retrieval analysis of porous tantalum hip implants. The purpose of this study was to investigate factors affecting bone ingrowth into porous tantalum hip implants. Methods. 126 porous tantalum acetabular shells and 7 femoral stems, were collected under an IRB-approved multicenter retrieval program. Acetabular shells that were grossly loose, cemented or complex revisions were excluded. Shells with visible bone on the surface were chosen. 20 acetabular shells (10 primary) and all femoral stems were dehydrated, embedded, sectioned, polished and bSEM imaged (Figure-1). Main shell revision reasons were infection (n=10,50%), femoral loosening (n=3,15%) and instability (n=3,15%). Analyzed implants were implanted for 2.3±1.7 years (shells) and 0.3±0.3 years (stems). Eight slices per shell and 5–7 slices per stem were analyzed. The analysis included bone area/pore area (BA/PA), BA/PA zonal depth analysis, extent of ingrowth and maximum depth of bone ingrowth. BA/PA zone depths were: Zone-1 (0–500um), Zone-2 (500–1000um) and Zone-3 (1000um-full depth). Nonparametric statistical tests investigated differences in bone measurements by location within an implant and implant type (Friedman's Variance and Kruskal-Wallis). Post-hoc Dunn tests were completed for subsequent pairwise comparisons. Spearman's rank correlation identified correlations between bone measurements and patient related variables (implantation time, age, height, weight, UCLA Activity Score). Statistical analyses were performed using PASW Statistics package. Results. BA/PA was not significantly different between acetabular shells (3.6±3.3%) and femoral stems (5.8% ± 3.9%, p=0.068). Extent of ingrowth was similar between shells (42 ± 28%) and stems (47±26%, p=0.825). Acetabular shells (76±23%) and stems (82±23%, p=0.707) had a similar maximum ingrowth depth. There were 9 shells and 2 stems (Figure-2) with full bone ingrowth into the porous tantalum substrate. When bone did not bridge the entire depth, a superficial layer of dense trabecular bone integrated with the porous layer was often observed. Localized regions of increased ingrowth were observed around screw holes. BA/PA in the superior region (4.1±2.4%) of the acetabular shells was significantly higher than in the inferior region (2.0±2.1%, p=0.047, Figure-3). Acetabular shells BA/PA in Zone-1(10.8%) was significantly higher than Zone-2 (4.9%, p=0.013) and Zone-3 (1.6%, p<0.001). BA/PA was significantly higher in Zone-1 (10.8%) than Zone-3 (2.3%, p=0.043) for femoral stems. There were no correlations between patient variables and bone measurements. Discussion. Our results demonstrate that bone ingrowth in porous tantalum hip components is concentrated in the superficial 500 um (Zone-1). This may provide the opportunity to reduce the thickness of the porous layer thus conserving more bone in future designs. Bone ingrowth in the acetabular shells was preferentially located around screw holes and superior region, similar to previous studies of other cementless designs. Only 40% of analyzed acetabular shells had implantation times greater than 2 years. Further work focused on longer term retrievals will increase understanding of the bone-implant interface. This study was supported by Zimmer and NIH (NIAMS) R01 AR47904

The purpose of this study was to evaluate the clinical and radiological findings in patients with avascular necrosis of the femoral head after implantation of a porous tantalum implant combined with autologous growth factors (AGF). The study included 40 hips in 30 patients. Of the 40 hips, 1 hip was stage I, 9 hips were stage II, 22 hips were stage III, and 8 hips were stage IV, according to the Steinberg classification system. Follow-up was 2 to 4 years. The porous tantalum (diameter of 10 mm, length ranging from 70 –110 mm) was implanted in the center of the necrotic area under fluoroscopic control. Clinical evaluation using the Harris hip score showed an increase from 66 to 96 points preoperatively to postoperatively in hips with stage II disease, from 60 to 85 points in hips with stage III, and from 60 to 80 points in hips with stage IV (p< 0,001). Of the 40 hips, the radiological stage in 20 hips (50%) remained stable, 17 (42.5%) progressed to an advanced stage and 3 hips (7.5%) underwent total hip arthroplasty (p< 0,001). Of the 17 hips that progressed, 7 were stage II, 7 were stage III, and 3 were stage IV. No material damage or implant migration was observed. Although failures are still observed with the use of porous tantalum, the minimal invasive technique and short operative time make tantalum a reasonable alternative in the treatment of AVN of the femoral head

A monobloc porous tantalum acetabular cup with a 28mm internal diameter was employed in 397 primary total hip replacements between August 1997 and December 2003. All patients were personally examined at yearly intervals for 3 years following surgery and at 2 year intervals thereafter. Thirty-one patients were known to have died and 69 hips were lost to follow up less than three years following implantation, leaving 297 hips (81%) available for review up to 10 years following implantation. The mean age at surgery was 66.2 years, with 12% of patients aged 80 years or older. 58% of the patients were female and 42% male. 82% of the patients had osteoarthritis. Clinical and radiographic data were analyzed for patients followed for a minimum of 3 years. Mean follow up was 5.4 years. The mean preoperative Harris hip score was 31, increasing to 89 at last follow up. The most common complication was dislocation. Eleven patients had dislocations in the early postoperative period: 4 required closed and 2 open reduction, and five required revision of the acetabular component for recurrent instability. Three patients (4 hips) with severe rheumatoid arthritis developed late instability and required acetabular revision. Four patients had a femoral fracture, 2 of which healed with slight settling and 1 of which required open reduction, subsequently became infected and required removal of the prosthesis. There was 1 superficial and 2 additional deep infections, one of which required component removal. Two patients had a fracture of the greater trochanter and required internal fixation. Four femoral components loosened, of which 3 were revised, all without involvement of the acetabular component. There were 3 transient sciatic nerve palsies; one resolved completely and two partially, although all 3 were lost to follow before 3 years. The porous tantalum monobloc acetabular components performed remarkably well at up to ten years following implantation. There were no instances of clinical or radiographic loosening, no osteolysis and no measurable wear visible on postoperative radiographs. The highly porous tantalum achieved reliable bony ingrowth in all cases. We hypothesize that the direct compression molding of the polyethylene into the porous tantalum substrate eliminated the backside wear and the flexion of the polyethylene liner that occurs in modular cups

Highly porous tantalum cups have been used in complex acetabular revisions for nearly 20 years but reports of long term results are limited. This study was designed to report ten year results of revision using a single porous tantalum cup design with special attention to re-operation for any reason, all-cause revision, and revision for aseptic loosening. Retrospective review of all revision THA cases performed from 1999–2006 using a highly porous tantalum acetabular component design with multiple screw holes and a cemented polyethylene liner (Zimmer Biomet, Warsaw, IN). Our institutional medical record and total joint registry were used to assess follow-up and xrays were reviewed. The Paprosky classification system was used to rate acetabular bone loss. Radiographic loosening was defined as new/progressive radiolucencies in all 3 acetabular zones, or cup migration (>2mm). Kaplan-Meier survivorship was used to assess survivorship free of cup revision/removal for any reason, and free of revision for aseptic loosening. Between 1999 and 2006 this tantalum cup was used in 916 revisions. Mean age: 66 (±6), BMI: 29 (±6), and male: 42%. Indications for revision: aseptic loosening 346 (38%), osteolysis 240 (26%), and infected arthroplasty 168 (18%). Large (3A or 3B) bone defects were present in 260, and pelvic discontinuity in 61. Reoperation for any reason: 133 (15%), but 84 of 133 cases did not require cup revision for instability (38) or femoral failure (24). Tantalum cup removal/revision was required in 49 (5.3%) for deep infection (39) and recurrent dislocation (6), and aseptic loosening (4). 10 year survivorship free of cup revision for any reason: 95% and for aseptic loosening: 99%. Radiographic review (mean 10 years): suspicious for aseptic loosening in another 4 cups. A highly porous tantalum acetabular component with multiple screws and a cemented polyethylene insert provided durable long term fixation for an array of acetabular revision problems. Long term aseptic loosening was very rare (<1%) and cup removal was mainly related to deep infection, and rarely dislocation

We report a series of sixteen total hip arthroplasties utilizing a porous tantalum trabecular metal acetabular component in patients with tumors of the hip. The study included eight men and eight women with an average age of 59.3 (range 22–80 years). Two patients had benign but locally recurrent disease destructive of bone (Langerhan’s Cell Histiocytosis and Rosi Dorfman Disease), while fourteen had malignant lesions. The latter included six myeloma, two lymphoma, and six metastatic carcinoma (three breast, one prostate, one lung, and one unknown site). Fifteen patients had prior radiation therapy. The technique used was determined by the extent of the lesion and the quality of remaining host bone. In eight patients major deficiencies necessitated augmentation of the porous tantalum cup with an anti-protrusio device “over -the top” a cup-cage construct. Porous tantalum augments were utilised with the cup to fill defects in the acetabulum in seven patients. Postoperative complications were seen in four cases (DVT, DIC, pneumonia, and one death from c. difficile colitis). Postoperatively, the majority of the patients had excellent pain relief and improved ambulatory status. No clinical failures have been observed at follow-up (mean 12.5 months, range twenty days-twenty-eight months). There have been no re-operations. Radiographically, no migration or evidence of implant loosening has been observed