Characteristics of bone ingrowth and interface mechanics of a new porous tantalum biomaterial

Management of metaphyseal bone loss in revision knee arthroplasty

Background and aim of the work: Revision total knee arthroplasty (TKA) is usually made more complex by the presence of bone defects, which may be caused by periprosthethic infection, polyethylene wear, implant loosening or fractures. The main aim of the present work is to review the available literature to understand the current options to manage with the bone loss during knee revisions. Methods: Available English literature for bone defects in revision TKAs has been evaluated looking at treatment options and their results in terms of clinical and radiological outcomes and failure rates. Results: Anderson Orthopaedic Research Institute (AORI) classification is the most frequently used because it helps in the choice of the most suitable treatment. Several options are available in the management of metaphyseal bone loss in revision knee arthroplasty. For small and contained defects (AORI type 1) cement with or without screws and auto- or allograft morcellized bone are available. In uncontained but mild defects (AORI type 2A) metal augments should be use while large and uncontained defects (AORI type 2B and 3) are best addressed with structural allograft or metal filling devices (cones and sleeves). Stemmed components, either cemented or cementless, are recommended to reduce the strain at the interface implant-host. Conclusions: The treatment of bone defects in revision TKAs has evolved during the last years providing different options with good results at a short/medium term follow up. With the increasing revision burden, further scientific evidence is requested to identify the best approach for each patient. Long-term clinical outcome as well as implant survival after revision TKA are still sub-optimal and depend upon many factors including cause for revision, surgical approach, type of implants used and various patient factors. (www.actabiomedica.it)

Management of metaphyseal bone loss in revision knee arthroplasty

BACKGROUND AND AIM OF THE WORK

Revision total knee arthroplasty (TKA) is usually made more complex by the presence of bone defects, which may be caused by periprosthethic infection, polyethylene wear, implant loosening or fractures. The main aim of the present work is to review the available literature to understand the current options to manage with the bone loss during knee revisions.

METHODS

Available English literature for bone defects in revision TKAs has been evaluated looking at treatment options and their results in terms of clinical and radiological outcomes and failure rates.

RESULTS

Anderson Orthopaedic Research Institute (AORI) classification is the most frequently used because it helps in the choice of the most suitable treatment. Several options are available in the management of metaphyseal bone loss in revision knee arthroplasty. For small and contained defects (AORI type 1) cement with or without screws and auto- or allograft morcellized bone are available. In uncontained but mild defects (AORI type 2A) metal augments should be use while large and uncontained defects (AORI type 2B and 3) are best addressed with structural allograft or metal filling devices (cones and sleeves). Stemmed components, either cemented or cementless, are recommended to reduce the strain at the interface implant-host.

CONCLUSIONS

The treatment of bone defects in revision TKAs has evolved during the last years providing different options with good results at a short/medium term follow up. With the increasing revision burden, further scientific evidence is requested to identify the best approach for each patient. Long-term clinical outcome as well as implant survival after revision TKA are still sub-optimal and depend upon many factors including cause for revision, surgical approach, type of implants used and various patient factors.

Surface hydroxyl groups regulate the osteogenic differentiation of mesenchymal stem cells on titanium and tantalum metals

Titanium (Ti) and tantalum (Ta) metals have been widely used as implants for their favorable mechanical features and good biocompatibility. However, the results on their osteogenic capacity have been conflicting due to the synergistic effects of complex and multiple material surface features (such as topography, surface chemistries etc.) on cellular behaviors. Here, we directly compare the osteogenic response of mesenchymal stem cells (MSCs) to Ti and Ta metal surfaces with alterable surface hydroxyl groups. Although no difference was found on both surface topographies, cellular adhesion, proliferation, and the expression of osteogenic-related markers were upregulated with the increasing amount of surface hydroxyl groups (-OH) after ultraviolet (UV) light treatment. Moreover, Ti showed better effects in promoting osteogenic differentiation of MSCs than Ta before UV light treatment, but demonstrated the opposite after UV light treatment. These results might be attributed to the comparative quantity of the distinct type of surface hydroxyl groups (bridging-OH and terminal-OH), which regulated the conformation of the initial protein adsorption and subsequent cellular behaviors. Our results demonstrate the central role of the surface hydroxyl groups in mediating cell-material interactions and implicate this interface as helping in optimizing osteointegration of Ti and Ta based orthopaedic and dental implants.

Micro-computed tomography analysis of early stage bone healing using micro-porous titanium mesh for guided bone regeneration: preliminary experiment in a canine model

The aim of this study was to evaluate the amount of bone formation beneath a defect area after treatment with titanium mesh membranes with different thicknesses and pore sizes alone or in combination with bone graft to induce bone formation during the early stage of healing time. The mandibular premolars were extracted bilaterally from three adult beagle dogs, and 8-mm-diameter bone defects were created on the buccal site of the premolar regions. Hydroxyapatite bone graft substitute was applied in the defect site unilaterally, and other site was left empty. Then, a novel micro-porous mesh (50 μm in pore diameter) or commercially available macro-porous titanium mesh (1700 μm in pore diameter) was placed on the defect and secured with screws. After 4 weeks, the mandibles were harvested, imaged using micro-computed tomography, and prepared for histological and morphometric evaluation. Higher new bone volumes (mm³), percentage of new bone volumes in the total defect volumes (bone ratio: %), and new bone area (mm²) through morphometric evaluation were found on the novel membranes with 50-μm-diameter pores compared to the commercial titanium mesh. Moreover, experiment sites without bone graft were observed with higher new bone volume and bone ratio compared with sites with bone graft. However, bone mineral density of novel mesh was observed to be lower compared with other experimental sites. Under the experimental condition, the result of this study suggests that titanium meshes with 50-μm-diameter pores were effective for guided bone regeneration in the early stage of healing.

Long-term results of a porous tantalum monoblock tibia component: clinical and radiographic results at follow-up of 10 years

Background

The purpose of this study is to assess the long-term follow-up of cementless total knee arthroplasty with the trabecular metal (TM) monoblock tibial component at an average 10-year follow-up. This report is an extension of our previously reported series of 108 TM tibias reported in 2011 (Unger and Duggan, 2011).

Methods

Fifty-eight of the original 108 knees were available for review. Each follow-up patient was evaluated by radiologic and clinical Knee Society Scores. The average follow-up was 10.2 years.

Results

Our results indicate excellent long-term survivorship (96.5%) with 2 confirmed tibia revisions, and 1 femoral revision for periprosthetic fracture and 1 patella open reduction internal fixation. X-ray evaluation demonstrated one patient with 1 mm medial polyethylene wear and a nonprogressive 1 mm of radiolucency on the medial side. All the other tibial components showed full bone apposition and incorporation. Knee Society Scores were excellent in all the patients seen on follow-up.

Conclusions

Long-term follow-up of TM monoblock tibia components confirm excellent survivorship and biologic implant fixation, with excellent outcomes and knee scores.

Cementless Porous Tantalum Monoblock Tibia vs Cemented Modular Tibia in Primary Total Knee Arthroplasty: A Meta-Analysis

BACKGROUND

With the introduction of new fixation systems and designs, there has been a recent reemergence of interest in cementless fixation of the tibial component in total knee arthroplasty. However, little is known regarding the clinical features and survivorship of the cementless porous tantalum monoblock tibial component compared to the conventional cemented modular tibial component.

METHODS

We conducted a literature search of multiple databases for comparative studies published before June 2015 that investigated the outcomes of cementless porous tantalum monoblock tibia vs conventional cemented modular tibia. A pooled analysis was performed. The outcomes of interest were postoperative functional score, range of motion, Western Ontario and McMaster University Osteoarthritis Index, total complications, reoperation, radiolucent lines, loosening of the tibial component, and length of operation.

RESULTS

Six studies involving 977 patients were eligible for the meta-analysis. The use of a cementless porous tantalum monoblock tibial component may associate with a slightly higher functional score, fewer radiolucent lines, and shorter operation. No significant difference was seen in regard to the range of motion, Western Ontario and McMaster University Osteoarthritis Index, total complications, reoperation, and loosening of the component between the 2 groups.

CONCLUSION

However, due to variation among the included studies, the use of cementless porous tantalum monoblock tibia seems to achieve no substantial superiority over that of the conventional cemented modular tibia at 5-year follow-up. Data concerning the long-term prognosis of this novel implant should continue to be collected and analyzed.

Tibial component with and without stem extension in a trabecular metal cone construct

PURPOSE

The purpose of this study was to investigate stability and strain distribution of a tibial plateau reconstruction with a trabecular metal cone while the tibial component is implanted with and without a stem, and whether prosthetic stability was influenced by bone mineral density. Trabecular metal cones are designed to fill up major bone defects in total knee arthroplasty. Tibial components can be implanted in combination with a stem, but it is unclear whether this is necessary after reconstruction with a trabecular metal cone. Implanting a stem can give extra stability, but may have negative side effects.

METHODS

Tibial revision arthroplasties with trabecular metal cones were performed after reconstruction of a 2B bone defect according to the Anderson Orthopedic Research Institute classification. Components were implanted in seven pairs of cadaveric tibiae; one tibia of each pair was implanted with stem and the other without. All specimens were loaded to one bodyweight alternating between the medial and lateral tibial component. Implant-bone micro-motions, bone strains, bone mineral density and correlations were measured and/or calculated.

RESULTS

Tibial components without a stem showed only more varus tilt [difference in median 0.14° (P < 0.05)], but this was not considered clinically relevant. Strain distribution did not differ. Bone mineral density only had an effect on the anterior/posterior tilt [ρ: -0.72 (P < 0.01)].

CONCLUSION

Tibial components, with or without a stem, which are implanted after reconstruction of major bone defects using trabecular metal cones produce very similar biomechanical conditions in terms of stability and strain distribution. If in vivo studies confirm that a stem extension is not mandatory, orthopaedic surgeons can decide not to implant a stem.

LEVEL OF EVIDENCE

II.

Enhanced osteointegration of tantalum-modified titanium implants with micro/nano-topography

Ta modification enhanced the osteointegration of an SLA surface with micro/nano topography and the possible mechanism might be activation of the Wnt pathway.

Clinical and radiologic outcomes of the second-generation Trabecular Metal™ glenoid for total shoulder replacements after 2-6 years follow-up

BACKGROUND

A porous tantalum glenoid component for total shoulder replacements was introduced in 2003 to promote biologic ingrowth. However, reports of component failure prompted design modifications. The purpose of this study is to present the largest series to date, of TSR with the second-generation Trabecular Metal™ glenoid component.

METHOD

A radiologic and clinical evaluation of the second-generation TM glenoid was conducted in consecutive cases of 76 shoulders (66 patients) with a mean follow-up of 43.2 months (range 24-72 months). Pre-operative VAS score, patient self-assessed ASES score, active shoulder range of motion, and radiologic assessment were recorded. Patients were recalled for latest follow-up clinical and radiologic evaluation.

RESULTS

On latest follow-up, the mean VAS scores (pre-op: 6.4-latest: 0.9) and ASES scores (pre-op: 36.9-latest: 88.5) improved. Active range of motion improved in all planes. There was no report of glenoid component migration, loosening, or humeral stem subsidence. The incidence of non-progressive radiolucency in the glenoid was 6.6 % (Franklin 1: 3 cases, Franklin 2: 2 cases). Post-operative complications involved dislocation (n = 2) which were reduced in ED, post-operative stiffness (n = 1), transient axillary nerve neuropraxia (n = 1), and supraspinatus tear which underwent arthroscopic repair at 16 months post-op. There were no revision surgeries for implant loosening nor glenoid component fracture at the peg-base plate junction.

CONCLUSIONS

The modifications established in the second-generation TM glenoid resulted to improve early to mid-term survivorship and clinical outcomes in TSR, with promise of long-term implant stability through bony ingrowth.

LEVEL OF EVIDENCE

Level IV, case series, treatment study.

Comparison of a novel porous titanium construct (Regenerex®) to a well proven porous coated tibial surface in cementless total knee arthroplasty - A prospective randomized RSA study with two-year follow-up

BACKGROUND

Regenerex is a novel porous titanium construct with a three-dimensional porous structure and biomechanical characteristics close to that of normal trabecular bone. The aim of this study was to compare this novel construct to a well-proven porous plasma sprayed tibial (PPS) implant after total knee arthroplasty.

METHODS

Sixty-one patients scheduled for an uncemented TKA were randomized to receive either a novel highly porous titanium construct Regenerex or the PPS tibial component. Radiostereometric analysis of the tibial components was performed postoperatively and at three, six, 12, and 24months with measurements of migration (segment motion and maximum total point motion (MTPM)).

RESULTS

Knee and function scores improved significantly from preoperatively to two-year follow-up. For both the Regenerex and the PPS the majority of migration appeared during the first three months and then stabilized. No statistically significant differences in MTPM were found in any follow-up between three and 24months. The Regenerex group had a lower migration rate between 12 and 24months compared with the PPS implants (p=0.03) but the PPS group had an initial significantly lower subsidence (p=0.04).

CONCLUSION

In conclusion the Regenerex implant could prove an effective scaffold material for coating of uncemented implants but did no better than the PPS component at 24months of follow-up. ClinicalTrials.gov identifier: NCT01936415.

Use of Oversized Highly Porous Cups in Acetabular Revision

This study assessed the efficacy of highly porous cups in revision total hip arthroplasty for Paprosky types II and III acetabular bone loss. The authors identified 33 acetabular revisions in 29 patients from a prospective database (66% type III, 7 with pelvic dissociation). Initial stability was achieved with interference fit between the anterior inferior iliac spine, pubis, and ischium with cups that were 2 to 4 mm larger than the reamed acetabulum and augmented with multiple screw fixations without allograft or wedges. At mean follow-up of 6 years (range, 2.7-7.7 years) after revision surgery, no dislocation, infection, or reoperation was noted. Mean satisfaction score was 6±3.2. Mean anteversion and abduction angles were 43°±4.6° and 21.5°±4.4°, respectively. Complications included limp in 13% of patients, wound issues in 10%, and heterotopic ossification in 17%. Osteointegration was seen in all cups, without any migration. Mean overall osteointegration, based on the average percentage of the 3 zones in both views, was 55%±21% (range, 25%-95%). The most osteointegration was seen in zone I (superior) and zone VI (posterior), and the least osseointegration was seen in zone II (medial) and zone IV (anterior). This method can provide reproducible results in acetabular revision arthroplasty.

Total Knee Arthroplasty Using Cementless Porous Tantalum Monoblock Tibial Component: A Minimum 10-Year Follow-Up

BACKGROUND

Cementless fixation in total knee arthroplasty (TKA) was introduced to improve the longevity of implants but has yet to be widely adopted because of reports of higher failure rates in some series. The cementless tantalum monoblock tibial component, in contrast, has shown successful short-term results, but long-term survivorship with this design is still lacking. The purpose of this study was to investigate the minimum 10-year clinical and radiographic results of the cementless tantalum monoblock tibial component in primary TKA.

METHODS

From March 2002 to March 2005, 33 patients (33 knees) underwent primary TKA with a cementless tantalum monoblock tibial component. All patients were followed clinically and radiographically for a minimum of 10 years (mean 11.5 years, range 10-13 years). No patients were lost to follow-up. The underlying diagnosis that led to the primary TKA was primary osteoarthritis in 31 knees and post-traumatic osteoarthritis in 2 knees.

RESULTS

None of the components was revised. At a minimum 10-year follow-up, the survivorship with reoperation for any reason as end point was 96.9%. With tibial component revision for aseptic loosening or osteolysis as the end point survivorship was 100%. There was no radiographic evidence of tibial component loosening, subsidence, osteolysis, or migration at the time of the latest follow-up. The mean Knee Society knee scores improved from 56 points preoperatively to 93 points at the last clinical visit.

CONCLUSION

The porous tantalum tibial monoblock component demonstrated excellent clinical and radiographic outcomes with no component revisions for aseptic loosening at a minimum follow-up of 10 years.

Long-Term Clinical and Radiographic Outcomes of Porous Tantalum Monoblock Acetabular Component in Primary Hip Arthroplasty: A Minimum of 15-Year Follow-Up

BACKGROUND

The porous tantalum monoblock cup has demonstrated excellent short-term and midterm clinical and radiographic outcomes in primary THA, but longer follow-up is necessary to confirm the durability of these results into the second decade. The purpose of this study is to report the clinical and radiographic outcomes for this monoblock cup with a minimum 15-year follow-up.

METHODS

From June 1998 to December 1999, 61 consecutive patients (63 hips) underwent primary THA with a tantalum monoblock acetabular component. All patients were followed clinically and radiographically for a minimum of 15 years. At a mean of 15.6 years (range, 15-16 years) of follow-up, 5 patients had died, and 4 had been lost to follow-up, leaving 52 patients (54 hips) for analysis. The underlying diagnosis that led to the primary THA was primary osteoarthritis in 43 hips, avascular necrosis in 4, developmental hip dysplasia in 3, rheumatoid arthritis in 3 and post-traumatic osteoarthritis in 1.

RESULTS

One cup was revised for deep infection; at surgery, the cup showed osseointegration. At a mean follow-up of 15.6 years (range, 15-16 years), the survivorship with cup revision for aseptic loosening as end point was 100%. There was no radiographic evidence of loosening, migration, or gross polyethylene wear at last follow-up. The mean Harris Hip Scores improved from 47 points preoperatively to 94 points.

CONCLUSION

The porous tantalum monoblock cup in primary THA demonstrated excellent clinical and radiographic outcomes with no failures because of osteolysis or loosening at a minimum follow-up of 15 years.

Tantalum trabecular metal implants in anterior cervical corpectomy and fusion: 2-year prospective analysis

Anterior cervical decompression for two or more cervical spondylotic levels can be performed using either multiple anterior cervical discectomies and fusion or anterior cervical corpectomy and fusion (ACCF). A variety of options for ACCF implants exist but to our knowledge, there is no clinical data for the use of tantalum trabecular metal implants (TTMI) for ACCF. A retrospective review was performed of prospectively collected data for ten patients undergoing ACCF with TTMI between 2011 and 2012. Radiological outcome was assessed by measuring the change in cervical (C) lordosis (fusion Cobb and C2-C7 Cobb), graft subsidence (anterior/posterior, determined by the subsidence of anterior/posterior body height of fused segments; cranial/caudal, determined by the cranial/caudal plate-to-disc distances) and rate of fusion using lateral cervical X-rays of patients at 0, 6, 12 and 24months post-operatively. The Neck Disability Index (NDI) assessed clinical outcome pre-operatively and at 6, 12 and 24months post-operatively. Cervical lordosis (Cobb angle of fused segment) was 5.2° (± 4.2°) at 0months and 6.0° (± 5.7°) at 24months post-operatively. Graft subsidence was observed to occur at 6months post-operatively and continued throughout follow-up. Anterior, posterior and caudal subsidence occurred more in the first 12months post-operatively than in the following 12months (p<0.05). Average pre-operative NDI was 45%. Average NDIs were 18%, 13% and 10% at 6, 12 and 24months post-operatively, respectively. ACCF patients treated with TTMI demonstrated stable cervical lordosis over 2years of follow-up and 100% fusion rates after 2years. Measures of subsidence appeared to decrease with time. Patients experienced improved clinical outcomes over the 2-year period.

In Vivo Response of Laser Processed Porous Titanium Implants for Load-Bearing Implants

Applications of porous metallic implants to enhance osseointegration of load-bearing implants are increasing. In this work, porous titanium implants, with 25 vol.% porosity, were manufactured using Laser Engineered Net Shaping (LENS™) to measure the influence of porosity towards bone tissue integration in vivo. Surfaces of the LENS™ processed porous Ti implants were further modified with TiO₂ nanotubes to improve cytocompatibility of these implants. We hypothesized that interconnected porosity created via additive manufacturing will enhance bone tissue integration in vivo. To test our hypothesis, in vivo experiments using a distal femur model of male Sprague-Dawley rats were performed for a period of 4 and 10 weeks. In vivo samples were characterized via micro-computed tomography (CT), histological imaging, scanning electron microscopy, and mechanical push-out tests. Our results indicate that porosity played an important role to establish early stage osseointegration forming strong interfacial bonding between the porous implants and the surrounding tissue, with or without surface modification, compared to dense Ti implants used as a control.

The functional response of bioactive titania-modified three-dimensional Ti-6Al-4V mesh structure toward providing a favorable pathway for intercellular communication and osteoincorporation

The objective of the study is to fundamentally elucidate the biological response of 3D printed mesh structures subjected to plasma electrolytic oxidation process through the study of osteoblast functions. The cellular activity of plasma electrolytic-oxidized mesh structure was explored in terms of cell-to-cell communication involving proliferation, synthesis of extracellular and intracellular proteins, and mineralization. Upon plasma electrolytic oxidation of the mesh structure, a thin layer of bioactive titania with pore size 1-3 µm was nucleated on the surface. The combination of microporous bioactive titania and interconnected porous architecture provided the desired pathway for supply of nutrients and oxygen to cells and tissue and a favorable osteogenic microenvironment for tissue on-growth and in-growth, in relation to the unmodified mesh structure. The formation of a confluent layer as envisaged via electron microscopy and quantitative assessment of the expression level of proteins (actin, vinculin, and fibronectin) point toward the determining role of surface-modified mesh structure in modulating osteoblasts functions. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2488-2501, 2016.

Total knee arthroplasty revision with trabecular tantalum cones: Preliminary retrospective study of 51 patients from two centres with a minimal 2-year follow-up

BACKGROUND

Successful management of large bone defects is of crucial importance when performing revision total knee arthroplasty (TKA). Trabecular tantalum cones may improve prosthesis fixation via their potential for reconstructing a stable metaphyseal support. The objective of this study was to evaluate the clinical and radiological outcomes and the complications of tantalum cones in revision TKA.

HYPOTHESIS

Trabecular tantalum cones provide stable and durable metaphyseal reconstruction when used during revision TKA.

MATERIAL AND METHODS

Trabecular Metal™ cones (Zimmer, Warsaw, IN, USA) were used for 52 revision TKAs in 51 patients (mean age, 68±9 years) managed in two centres between 2008 and 2013. A rotating hinge prosthesis was chosen for 38 (73%) knees and a condylar constrained knee prosthesis for 14 (27%) knees, with 37 tibial and 34 femoral cones. The two most common reasons for revision surgery were aseptic loosening (n=22, 42%) and infection (n=19, 37%). The bone loss was severe in most cases. At each centre, after a mean follow-up of 34 months (range, 24-52 months), two independent observers assessed the Knee Society Score (KSS), range of motion, mechanical axis, and osteo-integration for each patient.

RESULTS

Mean KSS increased from 46 preoperatively to 77 (P=0.001) at last follow-up and the mean KSS function from 39 to 57 (P=0.007). Mean range of motion improved from 93° (45°-120°) to 110° (65°-130°) (P=0.001). Mean postoperative mechanical axis was 180° (172°-190°). Radiographic evaluation showed evidence of osteo-integration for all cones. Four revisions were performed for recurrence of infection but none for mechanical failure.

DISCUSSION

The findings of our study confirm the biomechanical and biological reliability of Trabecular Metal™ cones used to fill metaphyseal bone defects during revision TKA.

LEVEL OF EVIDENCE

IV, retrospective therapeutic study.

Tantalum implanted entangled porous titanium promotes surface osseointegration and bone ingrowth

Porous Ti is considered to be an ideal graft material in orthopaedic and dental surgeries due to its similar spatial structures and mechanical properties to cancellous bone. In this work, to overcome the bioinertia of Ti, Ta-implanted entangled porous titanium (EPT) was constructed by plasma immersion ion implantation &deposition (PIII&D) method. Ca-implanted and unimplanted EPTs were investigated as control groups. Although no difference was found in surface topography and mechanical performances, both Ca- and Ta-implanted groups had better effects in promoting MG-63 cell viability, proliferation, differentiation, and mineralization than those of unimplanted group. The expression of osteogenic-related markers examined by qRT-PCR and western blotting was upregulated in Ca- and Ta-implanted groups. Moreover, Ta-implanted EPT group could reach a higher level of these effects than that of Ca-implanted group. Enhanced osseointegration of both Ca- and Ta-implanted EPT implants was demonstrated through in vivo experiments, including micro-CT evaluation, push-out test, sequential fluorescent labeling and histological observation. However, the Ta-implanted group possessed more stable and continuous osteogenic activity. Our results suggest that Ta-implanted EPT can be developed as one of the highly efficient graft material for bone reconstruction situations.

Femoral Component Survival in Hybrid Total Knee Arthroplasty

Although the majority of North American surgeons perform total knee arthroplasty by cementing both the femoral and the tibial components, hybrid fixation with a press-fit femur and cemented tibia is an alternative form of total knee arthroplasty performed by some. Currently, there is a paucity of literature evaluating long-term outcomes after hybrid total knee arthroplasty. As such, the purpose of the current study was to describe the long-term results of total knee arthroplasty performed using the hybrid technique. The authors retrospectively reviewed a total of 77 hybrid total knee arthroplasties with at least 12 years of follow-up. Clinical and radiographic evaluations were performed to determine patient function and the incidence of femoral component failure after hybrid total knee arthroplasty. At the time of last follow-up, 76 of 77 (99%) of the femoral components remained in place without evidence of loosening. One femoral component failed due to aseptic loosening and was ultimately revised to a cemented femoral component without further complication. In addition, 1 tibial component and 2 patellar components failed due to aseptic loosening. Four tibial polyethylene liners were revised for polyethylene wear. In conclusion, press-fit fixation of the femoral component is a reliable and durable alternative to cemented fixation. [Orthopedics. 2016; 39(3):181-186.].

Osteogenic potential of human adipose-tissue-derived mesenchymal stromal cells cultured on 3D-printed porous structured titanium

Integration of porous metal prosthetics, which restore form and function of irreversibly damaged joints, into remaining healthy bone is critical for implant success. We investigated the biological properties of adipose-tissue-derived mesenchymal stromal/stem cells (AMSCs) and addressed their potential to alter the in vitro microenvironment of implants. We employed human AMSCs as a practical source for musculoskeletal applications because these cells can be obtained in large quantities, are multipotent, and have trophic paracrine functions. AMSCs were cultured on surgical-grade porous titanium disks as a model for orthopedic implants. We monitored cell/substrate attachment, cell proliferation, multipotency, and differentiation phenotypes of AMSCs upon osteogenic induction. High-resolution scanning electron microscopy and histology revealed that AMSCs adhere to the porous metallic surface. Compared to standard tissue culture plastic, AMSCs grown in the porous titanium microenvironment showed differences in temporal expression for genes involved in cell cycle progression (CCNB2, HIST2H4), extracellular matrix production (COL1A1, COL3A1), mesenchymal lineage identity (ACTA2, CD248, CD44), osteoblastic transcription factors (DLX3, DLX5, ID3), and epigenetic regulators (EZH1, EZH2). We conclude that metal orthopedic implants can be effectively seeded with clinical-grade stem/stromal cells to create a pre-conditioned implant.

Trabecular Metal Use in Paprosky Type 2 and 3 Acetabular Defects: 5-Year Follow-Up

BACKGROUND

The reconstructive challenge of achieving a stable acetabulum in revision total hip arthroplasties in the presence of major osteolytic lesions has led to debate about the most appropriate surgical strategy to minimize implant-related failures. Trabecular metal (TM) implants have become popular but ongoing surveillance of their performance is required.

METHODS

We reviewed the clinical and radiological outcome of a consecutive series of 52 patients (55 hips) who had undergone revision total hip arthroplasty for Paprosky type 2 or 3 acetabular defects with TM revision acetabular shells between 2002 and 2008.

RESULTS

Four implant failures occurred (2 infections and 2 dislocations). Eleven patients from this cohort died (representing 12 hips) before the 5-year follow-up period giving us a follow-up of 78.2%. Implant survival at 5 years was 92% (95% confidence interval: 80.2%-96.9%). There were no cases of radiological loosening. The mean Oxford hip score was 34 (range, 5-48) at a mean follow-up of 63 months (range, 34-105 months).

CONCLUSIONS

We conclude that the use of TM revision shells for complex acetabular reconstruction yields satisfactory results.

Acetabular Reconstruction in Total Hip Arthroplasty

The difficulties encountered in dealing with the bone deficient acetabulum are amongst the greatest challenges in hip surgery. Acetabular reconstruction in revision total hip arthroplasty can successfully be achieved with hemispherical components featuring a porous or roughened ingrowth surface and options for placement of multiple screws for minor acetabular defect. Acetabular component selection is mostly based on the amount of bone loss present. In the presence of combined cavitary and segmental defects without superior acetabular coverage, reconstructions with a structural acetabular allograft protected by a cage or a custom-made triflange cage have been one of preferred surgical options. The use of a cage or ring over structural allograft bone for massive uncontained defects in acetabular revision can restore host bone stock and facilitate subsequent rerevision surgery to a certain extent. But high complication rates have been reported including aseptic loosening, infection, dislocation and metal failure. On the other hand, recent literature is reporting satisfactory outcomes with the use of modular augments combined with a hemispherical shell for major acetabular defect. Highly porous metals have been introduced for clinical use in arthroplasty surgery over the last decade. Their higher porosity and surface friction are ideal for acetabular revision, optimizing biological fixation. The use of trabecular metal cups in acetabular revision has yielded excellent clinical results. This article summarizes author's experience regarding revision acetabular reconstruction options following failed hip surgery including arthroplasty.

Does Increased Coefficient of Friction of Highly Porous Metal Increase Initial Stability at the Acetabular Interface?

BACKGROUND

Highly porous metal acetabular components illustrate a decreased rate of aseptic loosening in short-term follow-up compared with previous registry data. This study compared the effect of component surface roughness at the bone-implant interface and the quality of the bone on initial pressfit stability. The null hypothesis is that a standard porous coated acetabular cup would show no difference in initial stability as compared with a highly porous acetabular cup when subjected to a bending moment. Second, would bone mineral density (BMD) be a significant variable under these test conditions.

METHODS

In a cadaveric model, acetabular cup micromotion was measured during a 1-time cantilever bending moment applied to 2 generations of pressfit acetabular components. BMD data were also obtained from the femoral necks available for associated specimen.

RESULTS

The mean bending moment at 150 μm was not found to be significantly different for Gription (24.6 ± 14.0 N m) cups vs Porocoat (25 ± 10.2 N m; P > .84). The peak bending moment tolerated by Gription cups (33.9 ± 20.3 N m) was not found to be significantly different from Porocoat (33.5 ± 12.2 N m; P > .92). No correlation between BMD and bending moment at 150 μm of displacement could be identified.

CONCLUSION

The coefficient of friction provided by highly porous metal acetabular shells used in this study did not provide better resistance to migration under bending load when compared with a standard porous coated component.

3D Printing of Biocompatible Supramolecular Polymers and their Composites

A series of polymers capable of self-assembling into infinite networks via supramolecular interactions have been designed, synthesized, and characterized for use in 3D printing applications. The biocompatible polymers and their composites with silica nanoparticles were successfully utilized to deposit both simple cubic structures, as well as a more complex twisted pyramidal feature. The polymers were found to be not toxic to a chondrogenic cell line, according to ISO 10993-5 and 10993-12 standard tests and the cells attached to the supramolecular polymers as demonstrated by confocal microscopy. Silica nanoparticles were then dispersed within the polymer matrix, yielding a composite material which was optimized for inkjet printing. The hybrid material showed promise in preliminary tests to facilitate the 3D deposition of a more complex structure.

Promising Mid-term Results With a Cup-cage Construct for Large Acetabular Defects and Pelvic Discontinuity

BACKGROUND

Restoring normal anatomy and achieving stable fixation of the acetabular component can be especially challenging when the surgeon must deal with severe acetabular defects and/or pelvic discontinuity. The cup-cage (CC) construct, where an ilioischial cage is cemented within a biologically fixed porous metal cup, has emerged as an excellent option to treat such challenges.

QUESTIONS/PURPOSES

We sought to determine (1) mid-term Kaplan-Meier survival; (2) clinical outcomes based on Merle d'Aubigné-Postel scores; (3) radiological outcomes based primarily on construct migration; and (4) the complication rate for a series of 67 CC procedures performed at our institution.

METHODS

All hip revision procedures between January 2003 and March 2012 where a CC was used (with the exception of tumor cases or acute fracture; four total cases) that had a minimum 2-year followup and that had been seen within the last 2 years were included in this retrospective review. Acetabular bone loss and presence of pelvic discontinuity were assessed according to the Gross classification. Sixty-seven CC procedures with an average followup of 74 months (range, 24-135 months; SD, 34.3) months were identified; 26 of 67 (39%) were Gross Type IV and 41 of 67 (61%) were Gross Type V (pelvic discontinuity). Postoperative clinical and radiological evaluation was done annually. Merle d'Aubigné-Postel scores were recorded and all radiographs were compared with the 6-week postoperative radiographs to evaluate for radiographic loosening or migration. Failure was defined as revision surgery for any cause, including infection.

RESULTS

The 5-year Kaplan-Meier survival rate with revision for any cause representing failure was 93% (95% confidence interval [CI], 83.1-97.4), and the 10-year survival rate was 85% (95% CI, 67.2-93.8). The Merle d'Aubigné-Postel score improved significantly from a mean of 6 preoperatively to 13 postoperatively (p < 0.001). Four CC had nonprogressive radiological migration of the ischial flange and they remain stable.

CONCLUSIONS

We believe that the CC construct is a suitable choice to treat chronic pelvic discontinuity; it also remains a reliable option for the treatment of severe acetabular bone defects if stable fixation cannot be obtained through the use of a trabecular metal cup with or without augments.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Combining 3D human in vitro methods for a 3Rs evaluation of novel titanium surfaces in orthopaedic applications

In this study, we report on a group of complementary human osteoblast in vitro test methods for the preclinical evaluation of 3D porous titanium surfaces. The surfaces were prepared by additive manufacturing (electron beam melting [EBM]) and plasma spraying, allowing the creation of complex lattice surface geometries. Physical properties of the surfaces were characterized by SEM and profilometry and 3D in vitro cell culture using human osteoblasts. Primary human osteoblast cells were found to elicit greater differences between titanium sample surfaces than an MG63 osteoblast-like cell line, particularly in terms of cell survival. Surface morphology was associated with higher osteoblast metabolic activity and mineralization on rougher titanium plasma spray coated surfaces than smoother surfaces. Differences in osteoblast survival and metabolic activity on titanium lattice structures were also found, despite analogous surface morphology at the cellular level. 3D confocal microscopy identified osteoblast organization within complex titanium surface geometries, adhesion, spreading, and alignment to the biomaterial strut geometries. Mineralized nodule formation throughout the lattice structures was also observed, and indicative of early markers of bone in-growth on such materials. Testing methods such as those presented are not traditionally considered by medical device manufacturers, but we suggest have value as an increasingly vital tool in efficiently translating pre-clinical studies, especially in balance with current regulatory practice, commercial demands, the 3Rs, and the relative merits of in vitro and in vivo studies. Biotechnol. Bioeng. 2016;113: 1586-1599. © 2015 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.

Current evidence and future directions for research into the use of tantalum in soft tissue re-attachment surgery

The use of tantalum is well established in orthopaedic surgery.

Effects of Reduction Osteotomy on Gap Balancing During Total Knee Arthroplasty for Severe Varus Deformity

This study aimed to assess the effects of down-sizing and lateralizing of the tibial component (reduction osteotomy) on gap balancing in TKA, and the clinical feasibility of an uncemented modular trabecular metal tibial tray in this technique. Reduction osteotomy was performed for 39 knees of 36 patients with knee OA with a mean tibiofemoral angle of 21° varus. In 20 knees, appropriate gap balance was achieved by release of the deep medial collateral ligament alone. Flexion gap imbalance could be reduced by approximately 1.7° and 2.8° for 4-mm osteotomy and 8-mm osteotomy, respectively. Within the first postoperative year, clinically-stable tibial component subsidence was observed in 9 knees, but it was not progressive, and the clinical results were excellent at a mean follow-up of 3.3 years.

Modified porous tantalum rod technique for the treatment of femoral head osteonecrosis

AIM: To study a modified porous tantalum technique for the treatment of osteonecrosis of the femoral head.

METHODS: The porous tantalum rod was combined with endoscopy, curettage, autologous bone grafting and use of bone marrow aspirates from iliac crest aspiration in 49 patients (58 hips) with a mean age of 38 years. The majority of the patients had idiopathic osteonecrosis, followed by corticosteroid-induced osteonecrosis. Thirty-eight hips were of Steinberg stage II disease and 20 hips were of stage III disease. Patients were followed for 5 years and were evaluated clinically with the Merle D’Aubigne and Postel score and radiologically. The primary outcome of the study was survival based on the conversion to total hip arthroplasty (THA). Secondary outcomes included deterioration of the osteonecrosis to a higher disease stage at 5 years compared to the preoperative period and identification of factors that were associated with survival. The Kaplan-Meier survival analysis was performed to evaluate the survivorship of the prosthesis, and the Fisher exact test was performed to test associations between various parameters with survival.

RESULTS: No patient developed any serious intraoperative or postoperative complication including implant loosening or migration and donor site morbidity. During the 5-year follow up, 1 patient died, 7 patients had disease progression and 4 hips were converted to THA. The 5-year survival based on conversion to THA was 93.1% and the respective rate based on disease progression was 87.9%. Stage II disease was associated with statistically significant better survival rates compared to stage III disease (P = 0.04). The comparison between idiopathic and non-idiopathic osteonecrosis and between steroid-induced and non-steroid-induced osteonecrosis did not showed any statistically significant difference in survival rates. The clinical evaluation revealed statistically significantly improved Merle d’Aubigne scores at 12 mo postoperatively compared to the preoperative period (P < 0.001). The mean preoperative Merle d’Aubigne score was 13.0 (SD: 1.8). The respective score at 12 mo improved to 17.0 (SD: 2.0). The 12-mo mean score was retained at 5 years.

CONCLUSION: The modified porous tantalum rod technique presented here showed encouraging outcomes. The survival rates based on conversion to THA are the lowest reported in the published literature.

Interplay between self-assembled structure of bone morphogenetic protein-2 (BMP-2) and osteoblast functions in three-dimensional titanium alloy scaffolds: Stimulation of osteogenic activity

Three-dimensional cellular scaffolds are receiving significant attention in bone tissue engineering to treat segmental bone defects. However, there are indications of lack of significant osteoinductive ability of three-dimensional cellular scaffolds. In this regard, the objective of the study is to elucidate the interplay between bone morphogenetic protein (BMP-2) and osteoblast functions on 3D mesh structures with different porosities and pore size that were fabricated by electron beam melting. Self-assembled dendritic microstructure with interconnected cellular-type morphology of BMP-2 on 3D scaffolds stimulated osteoblast functions including adhesion, proliferation, and mineralization, with prominent effect on 2-mm mesh. Furthermore, immunofluorescence studies demonstrated higher density and viability of osteoblasts on lower porosity mesh structure (2 mm) as compared to 3- and 4-mm mesh structures. Enhanced filopodia cellular extensions with extensive cell spreading was observed on BMP-2 treated mesh structures, a behavior that is attributed to the unique self-assembled structure of BMP-2 that effectively communicates with the cells. The study underscores the potential of BMP-2 in imparting osteoinductive capability to the 3D printed scaffolds.

Porous titanium bases for osteochondral tissue engineering

Tissue engineering of osteochondral grafts may offer a cell-based alternative to native allografts, which are in short supply. Previous studies promote the fabrication of grafts consisting of a viable cell-seeded hydrogel integrated atop a porous, bone-like metal. Advantages of the manufacturing process have led to the evaluation of porous titanium as the bone-like base material. Here, porous titanium was shown to support the growth of cartilage to produce native levels of Young's modulus, using a clinically relevant cell source. Mechanical and biochemical properties were similar or higher for the osteochondral constructs compared to chondral-only controls. Further investigation into the mechanical influence of the base on the composite material suggests that underlying pores may decrease interstitial fluid pressurization and applied strains, which may be overcome by alterations to the base structure. Future studies aim to optimize titanium-based tissue engineered osteochondral constructs to best match the structural architecture and strength of native grafts.

STATEMENT OF SIGNIFICANCE

The studies described in this manuscript follow up on previous studies from our lab pertaining to the fabrication of osteochondral grafts that consist of a bone-like porous metal and a chondrocyte-seeded hydrogel. Here, tissue engineered osteochondral grafts were cultured to native stiffness using adult chondrocytes, a clinically relevant cell source, and a porous titanium base, a material currently used in clinical implants. This porous titanium is manufactured via selective laser melting, offering the advantages of precise control over shape, pore size, and orientation. Additionally, this manuscript describes the mechanical influence of the porous base, which may have applicability to porous bases derived from other materials.

In Vivo Magnetic Resonance Imaging Evaluation of Porous Tantalum Interbody Fusion Devices in a Porcine Spinal Arthrodesis Model

STUDY DESIGN

Animal experimental study.

OBJECTIVE

To investigate the use of magnetic resonance (MR) imaging in the assessment of lumbar interbody fusion using porous tantalum implants in a porcine spinal fusion model.

SUMMARY OF BACKGROUND DATA

Porous tantalum has been used successfully as a spinal interbody fusion device. However, to our knowledge, there has been no consensus on the optimal technique for evaluating spinal fusion when using porous tantalum implants.

METHODS

Twelve 12-week-old female Danish Landrace pigs underwent 3 levels of anterior lumbar interbody fusion at L2-3, L4-5 and L6-7. One level was fused using a solid porous tantalum cage with pedicle screw fixation. The other 2 levels were fused using a hollow porous tantalum ring packed with autograft and stabilized anteriorly with staples. Six months postoperatively, T1-weighted, T2-weighted, and gadolinium-DTPA contrast-enhanced MRI were obtained on a GE 1.5-T unit. After sacrifice, conventional radiograph and histological examination were carried out.

RESULTS

Eleven pigs went through the experiment without complications. On all the MR sequences, there were significant higher signal intensity bands at the vertebrae-implant interface of nonfused segments compared with that of fused segments and the vertebral bone and implants themselves (P < 0.001). There was an agreement between histological findings of fibrous tissues surrounding the implants and the high signal intensity band on T1- and T2-weighted MR images respectively (sensitivity 69.6% and 56.5%, specificity 90.7% and 95.3%), both of which were superior to conventional radiograph images (sensitivity 52.2%, specificity 97.7%), especially the T1-weighted MR images.

CONCLUSION

MR imaging could be an effective and noninvasive way to determine the fusion status of tantalum metal implants. Compared with T2-weighted MR imaging and conventional radiograph, T1-weighted spin-echo MR imaging is more sensitive and specific in detecting nonunion via the lucency between the vertebral body and tantalum metal device.

LEVEL OF EVIDENCE

N/A.

Tantalum Cones Provide Durable Mid-term Fixation in Revision TKA

BACKGROUND

Multiple studies have reported favorable short-term outcomes using tantalum cones to reconstruct massive bone defects during revision TKA. However, longer-term followup is needed to determine the durability of these reconstructions.

QUESTIONS/PURPOSES

We wished to determine the mid-term (1) reoperation rates for septic and aseptic causes, (2) radiologic findings of osseointegration, and (3) clinical outcomes based on the Knee Society score in patients who underwent revision knee arthroplasty with tantalum cones for severe bone loss.

METHODS

We retrospectively evaluated records of 18 patients (18 knees) who underwent revision knee arthroplasty with use of tantalum cones between 2005 and 2008; the primary indications for use of this approach were to reconstruct massive bone defects classified as Anderson Orthopaedic Research Institute Types 2B and 3. During this period, all defects of this type were treated with this approach and no cones were used for more-minor defects. A total of 26 cones (13 tibial and 13 femoral) were implanted. There were 12 female and six male patients with a mean age of 73 years (range, 55-84 years) at the time of revision. The indication for the revision included aseptic loosening (five patients) and second-stage reimplantation for deep infection (13 patients). Patients were followed for a mean of 6 years (range, 5-8 years). No patient was lost to followup. Clinical and radiographic outcomes were assessed with the Knee Society clinical rating system and radiographic evaluation system.

RESULTS

There have been two reoperations for recurrent infection; at surgery, the two cones showed osseointegration. No evidence of loosening or migration of any implant was noted on the most recent radiographs. Knee Society knee scores improved from a mean of 31 points before surgery to 77 points at latest followup (p < 0.001), and function scores improved from a mean of 22 points to 65 points (p < 0.001).

CONCLUSIONS

Tantalum cones for reconstruction of massive bone defects in revision knee arthroplasty provided secure fixation with excellent results at average followup of 6 years, although this series included relatively few patients. These devices are a viable option for surgeons to use in situations with severe bone loss. Further studies with longer followups are needed to confirm the durability of these reconstructions.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Cementless Acetabular Reconstruction for Arthropathy in Old Acetabular Fractures

This study was conducted to identify the factors influencing mechanical failure of cementless acetabular reconstruction for arthropathy after operative treatment of acetabular fractures. Fifty-six patients (56 hips) undergoing cementless total hip arthroplasty were enrolled and followed for a mean of 120 months (range, 60-180 months). The 10-year survival rate, with mechanical failure (radiographic loosening or revision due to aseptic loosening) as the endpoint, was analyzed with respect to sex, age, body mass index (BMI), acetabular bone deficiency, sclerotic changes to the acetabulum, and use of the Trabecular Metal (TM) cup (Zimmer, Inc, Warsaw, Indiana). Mean 10-year survival rates of the acetabular component were as follows: 80% (range, 65%-96%) in males and 100% in females (P=.032); 77% (range, 60%-95%) in patients younger than 50 years and 91% (range, 82%-100%) in older patients (P=.027); 88% (range, 78%-98%) in patients with a BMI less than 30 kg/m(2) and 81% (range, 74%-89%) in patients with a BMI of 30 kg/m(2) or higher (P=.068); 54% (range, 32%-76%) in patients manifesting large acetabular deficiency and 90% (range, 78%-100%) in the remaining patients (P<.001); 78% (range, 65%-91%) in patients with the presence of sclerotic acetabulum and 92% (range, 86%-100%) in patients with the absence of sclerotic acetabulum (P=.022); and 82% (range, 73%-100%) in patients who received a conventional shell and 100% in patients who received the TM cup (P=.039). Male sex, age younger than 50 years, large acetabular deficiency, and sclerotic changes of the acetabulum were significant factors contributing to the mechanical failure of cementless acetabular reconstruction performed for old acetabular fractures treated with open reduction and internal fixation. Use of the TM cup seemed able to prolong the endurance of the acetabular component in the subsequent reconstruction.

The Use of Trabecular Metal Cones in Complex Primary and Revision Total Knee Arthroplasty

Trabecular metal cones are one option for treating osseous defects during TKA. A total of 83 consecutive TKAs utilizing cones with an average of 40 months follow-up were reviewed. There were 24 males and 59 females, with an average age of 69 years old. Four were complex primary and 79 were revision procedures. Of 83 patients, 10 (12%) required repeat revision surgery (8 infections, one periprosthetic fracture, one aseptic loosening) and overall, 37 of 83 patients (45%) experienced at least one complication. Of 73 unrevised knees, 72 (99%) demonstrated radiographic evidence of osseointegration. Despite a high complication rate in this population, trabecular metal cones represent an attractive option for managing bone loss in complex primary and revision TKA with a high rate of osseointegration.

Short Term Outcomes of a Hydroxyapatite Coated Metal Backed Patella

We retrospectively evaluated the records and radiographs of 101 knees with a hydroxyapatite coated metal backed patella (HAP) and 50 knees with a cemented polyethylene patella (CP) with minimum two year clinical follow up. There were no patellar revisions during the study period. Patients in both the HAP and CP groups had similar clinical outcomes at final follow-up. Forty-five percent of patients in the HAP group had 1-2mm areas of decreased trabecular bone density around the pegs, which were not observed in the CP group, and may represent stress shielding. This uncemented HAP component has satisfactory early clinical outcomes, but long-term follow up is necessary to determine the durability of this implant.

Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty

Titanium-based highly-porous metal cups have been introduced as a relatively new alternative for enhanced acetabular fixation during revision THA; limited number of studies have evaluated its outcomes. We aimed to assess the clinical, functional, and patient-reported outcomes following the use of new generation highly-porous titanium acetabular implants in the revision setting. Seventy-one revisions were (1:1) matched to a conventional porous-coated cohort and were followed-up clinically and radiographically for at least 2-years. Non-significant differences in overall aseptic-survivorship were found across all types of acetabular defects comparing both cohorts (P=0.3). The overall HHS, UCLA, and SF-36 scores were similar between both cohorts. It remains to be seen if the great potential for enhanced osseointegration translates into improved long-term survivorship compared to conventional-porous devices.

Trabecular Metal Augments for the Management of Paprosky Type III Defects Without Pelvic Discontinuity

Fifty-five hips undergoing acetabular reconstruction with trabecular metal (TM)-coated cup and TM augments were reviewed at an average follow up of 53.7 months (36-91). Bony defects were Paprosky type IIIA in 42 and type IIIB without pelvic discontinuity in 13 hips. The average HHS increased from 40 (27-52) preoperatively to 90.5 (61-100) postoperatively (P<0.0001). Four (7.3%) of 55 hips underwent acetabular components revision: three cases of loosening (5.4%), and one of recurrent instability (1.8%) were reported. Survival rate at 2 and 5 years was 96.4% and 92.8%. In conclusion, the use of TM-coated cups and augments could be considered an effective management of Paprosky type III defects without pelvic discontinuity providing good clinical and radiographic outcomes in the mid term.

Performance of Porous Tantalum vs. Titanium Cup in Total Hip Arthroplasty: Randomized Trial with Minimum 10-Year Follow-Up

Porous tantalum monoblock cups have been proposed to improve survivorship of cementless primary THA. However, there are few direct comparative trials to established implants such as porous-coated titanium cups. 113 patients were randomized into two groups according to the cup: a porous tantalum monoblock cup (TM) or a porous-coated titanium monoblock cup (control). At a mean of 12 years after THA, no implants migrated in both groups. Two TM patients (4%) and 13 control patients (33%) presented with radiolucency around the cup (P<0.001). In the control group, 1 cup (2%) was revised for aseptic loosening. At 12 years post-implantation, porous tantalum monoblock cups demonstrated 100% survivorship, and significantly less radiolucency as compared to porous-coated titanium monoblock cups.