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.

Revision total hip replacements are likely to have higher complication rates than primary procedures due to the poor quality of the original bone. This may be constrained to achieve adequate fixation strength to prevent future “aseptic loosening” [1]. A thin, slightly flexible, acetabular component with a three dimensional, titanium foam in-growth surface has been developed to compensate for inferior bone quality and decreased contact area between the host bone and implant by better distributing loads across the remaining acetabulum in a revision situation. This is assumed to result in more uniform bone apposition to the implant by minimizing stress concentrations at the implant/bone contact points that may be associated with a thicker, stiffer acetabular component, resulting in improved implant performance.[2] To assemble the liner to the shell, the use of PMMA bone cement is recommended at the interface between the polyethylene insert and the acetabular shell as a locking mechanism configuration may not be ideal due to the flexibility in the shell [3].

The purpose of this study was to quantify the mechanical integrity of a thin acetabular shell with a cemented liner in a laboratory bench-top total hip revision condition. Two-point loading in an unsupported cavity was created in a polyurethane foam block to mimic the contact of the anterior and posterior columns in an acetabulum with superior and inferior defects. This simulates the deformation in an acetabular shell when loaded anatomically [4]. The application has been extended to evaluate the fatigue performance of the Titanium metal foam Revision Non-Modular Shell Sequentially Cross Linked PE All-Poly Inserts and its influence on liner fixation.

Between 1986 and 1999, 94 patients (96 hips) including 31 male and 63 female (mean age 59.5 years), with massive bone loss had a revision hip arthroplasty using an allograft-prosthesis composite (APC). A previous history of infection was present in 21 of these cases.

At an average follow-up of 11 years (range, 8 to 20 years), 72 patients were alive, 21 patients died, and 1 patient was lost to follow-up. Major complications occurred in 33 cases: femoral stem loosening (12); dislocation (15); periprosthetic fracture (10); and infection (7). Further revision surgery was performed in 21 of the 96 cases including revision of the acetabular component (3), femoral APC (16) or both (2). The 10 year survival of the APCs was 68.8% (95% CI 58.6%–79%, 26 cases remaining at risk). There was no statistically significant difference in survival time between gender, age, indication for APC (including infection), surgical approach and APC technique. Statistically significant factors negatively impacting APC survival included two or more prior revisions, severity of preoperative bone loss (Paprosky type IV) and use of plates and screws (p< 0.05). Statistically significant improvement in APC survival was identified in those reconstructions in which cement was used for proximal fixation of the femoral component within the allograft (p< 0.05).

Reconstruction with an allograft-implant composite is a demanding procedure. However, preservation of bone stock is a major advantage.

Aim: The purpose of our study is to present the survival results, clinical outcome and complications from the use of APC in cases with a history of periprosthetic infection.

Materials and Methods: Between 1986 and 1999, twenty-two patients (twenty-two hips) 11 male and 11 female (mean age 57.5 years – range 38 to 77 years) with massive bone loss (Paprosky IIIA 2 cases, IIIB 4 cases, and IV 16 cases) were included to our study. They all had a history of periprosthetic infection after an average of 3.3 (range 1 to 5) revision hip arthroplasties and were submitted to a two stage revision arthroplasty using an allograft-prosthesis composite.

Results: At an average follow-up of eleven years (range, eight to twenty years), 14 patients were alive, 7 patients died, and 1 patient was lost to follow-up. The ten year survival of the allograft-prosthesis composites was 74.9 per cent (95 per cent confidence interval 55.1 to 94.7 per cent, 4 cases remaining at risk). Seven cases presented with APC failure needing re-revision, 2 due to re-infection (4 and 23 months from revision by the same microorganism species as for the initial infection (Staph aureus to both cases), 3 due to allograft non union (at 21, 43, 79 months) and 2 cases due to graft resorption (164, 175 months post revision). Delayed healing and wound drainage occurred to 2 more cases.

Conclusion: Reconstruction of massive proximal femoral bone loss with an allograft-implant composite is a demanding procedure. Biologic means of reconstruction is a major advantage preserving bone stock for future surgery. However, high complication rate should be considered.

Background: Massive bone loss from the proximal femur is a complex problem, occurring in multiple-revision hip arthroplasties, and malignancy. Allograft prosthetic composites (APCs) are used to restore bone loss and provide better function of the limb.

Material and Methods: Between 1986 and 1999, 94 patients (96 hips) including 31 male and 63 female (mean age 59.5 years), with massive bone loss due to an average of 2 previous revisions, had a revision hip arthroplasty using an allograft-prosthesis composite (APC). A previous history of infection was present in 21 of these cases.

Results: At an average follow-up of 11 years (range, 8 to 20 years), 72 patients were alive, 21 patients died, and 1 patient was lost to follow-up. Major complications occurred in 33 cases: femoral stem loosening (12); dislocation (15); periprosthetic fracture (10); and infection (7). Minor complications occurred in 13 other cases. Further revision surgery was performed in 21 of the 96 cases including revision of the acetabular component (3), femoral APC (16) or both (2). The 10 year survival of the APCs was 68.8% (95% CI 58.6%–79%, 26 cases remaining at risk). There was no statistically significant difference in survival time between gender, age, indication for APC (including infection), surgical approach and APC technique. Statistically significant factors negatively impacting APC survival included two or more prior revisions, severity of preoperative bone loss (Paprosky type IV) and use of plates and screws (p< 0.05). Statistically significant improvement in APC survival was identified in those reconstructions in which cement was used for proximal fixation of the femoral component within the allograft (p< 0.05).

Conclusion: Reconstruction of massive proximal femoral bone loss with an allograft-implant composite is a demanding procedure. Preservation of bone stock is a great advantage of this biologic means of reconstruction. Specific technical issues should be known and followed so to avoid failure and need for early re-revision

Purpose of the study: The majority of acetabular bone defects observed during revision hip surgery can be treated with a hemispheric implant, associated or not with a bone graft. In many patients however, loss of bone stock is so great that a more complex system must be used with a sustaining ring, multilobulated implants, or massive allografts. All have their technical difficulties or problems with fixation. The purpose of this work was to evaluate a new technique for acetabular reconstruction using modular implants fashioned with a new biomaterial, porous tantalum, which had specific properties favoring osteointegration.

Material and methods: These modular implants were fashioned so as to enable reconstruction of the acetabular cavity in cases with complex loss of bone stock. The design allows simultaneous biological incorporation and mechanical support with a press-fit hemispheric cup. These implants were used for 16 hips (16 patients, 12 women and 4 men, mean age 63.6 years, age range 34–86 years). These patients were followed for 31.9 months on average (range 24–39 months). The acetabular defects were Paprosky 2A (n=1), 2B ‘n=3), 2C (n=1), 3A (n=5), 3B (n=6). On average, these patients had undergone 2.8 cup replacements (1–9) on the same hip.

Results: The mean Harris hip score improved from 39.31 (range 33–52) preoperatively to 75.18 (range 52–92) at last follow-up. Preoperatively, the center of rotation of the prosthetic hip was situated a a mean horizontal distance of 18.6 mm (range −3 to 46 mm) and a mean vertical distance of 27.6 mm (range −16 to 52 mm) from the ideal center of rotation according to Ranawat. Postoperatively, the prosthetic center of rotation was situated at a mean horizontal distance of 10.5 mm (range 1–25 mm) and a mean vertical distance of 7.4 mm (range −15 to 25 mm) front the ideal center of rotation. None of the implants presented loosening or migration at last follow-up.

Discussion: At short-term follow-up, this modular system for acetabular reconstruction has provided good results for acetabular reconstruction which can accept a hemispheric cup alone and which would have required use of other reconstruction methods such as structural allografts, sustaining rings or other.

Conclusion: A longer follow-up will be needed to determine whether these good clinical and radiological results persist with time.

There has been a longstanding need for a structural biomaterial that can serve as a bone graft substitute or implant construct and is effective for fixation by bone ingrowth. A porous tantalum material was developed to address these issues. The purpose of this paper and presnetation is to describe the properties and 2 to 5 year clinical results of porous tantalum in various reconstructive orthopaedic procedures.

Porous tantalum has been used to manufacture primary and revision acetabular cups, acetabular augments, tibial and patella implants, patellar augments, structural devices for the treatment of osteonecrosis, and spinal fusion implants. Clinical follow-up includes: 2–5 year clinical and radiographic evaluation of: 414 monoblock cups in primary THA, 36 monoblock cups and 587 revision hemispheres used in revision THR, 16 hips revised with acetabular augments and revision hemispheres; 2 to 4 years for 101 tibial implants used in primary TKR and 69 patellas used in cementless TKR; 2–4 years for 11 patellar augments in salvage TKR, 1–5 years for 53 revision TKRs using knee spacers; 1–4 years for 91 osteone-crosis hip implants; and for 15 cervical fusion cases.

This innovative tantalum implant material with trabecular architecture possesses advantages in stiffness, friction coefficient, porosity, rate and extent of tissue ingrowth, and versatility in manufacturing of structural devices. It has been clinically validated in numerous and diverse reconstructive procedures.

Press-fit acetabular reconstructions have become the standard THA; however, controversies remain. The purpose of this study was to critically evaluate serial radiographs for initial cup stability, i.e. gaps and signs of periacetabular interface changes for a porous tantalum monoblock socket.

A multicenter study evaluating 574 primary THRs (542 patients) performed by 9 surgeons at 7 hospitals, all with a monoblock cup without screws. Analyses included clinical outcomes and detailed 2-year minimum radiographic evaluation by one independent observer (mean follow-up, 33 months).

Complications included 9 intra-operative acetabular fractures. Among the 123 cases excluded from radiographic evaluations: deceased (19), lost-to-follow-up (8), 7 early revisions (recurrent dislocations (6) and one trauma-related loosening), and sepsis (3). Patient demographics (414 hips): mean age 65 years (19–93); 58 percent females. Baseline radiographs revealed 113 zones in 85 hips (21 percent) with acetabular gaps; 36 in zone I, 72 in zone II, and 5 in zone III. Of these radiolucencies, 57 zones were 1 mm or less and 56 zones ranged from 2 to 5 mm. At last follow-up, 64 hips (75 percent) had complete gap fill-in, including 100 percent of gaps greater than 3 mm.

There were no socket migrations, no evidence of lysis, no revisions for loosening, and no complete periacetabular interface radiolucencies. The fill-in of preexisting OA cysts and gaps is attributed to adequate initial stability and osteointegration into the porous tantalum. These results suggest that a monoblock cup without screws is an attractive option in THA.

Introduction and purpose: Two-stage reimplantation of a hip replacement is the treatment of choice for deep periprosthetic infections. The purpose of this study is to analyse the survival of the femoral component in two-stage hip replacement reimplantations and compare the results of cemented and cementless components.

Materials and methods: Between 1988 and 1998 our hospital carried out 169 two-stage reimplantations for treatment of first episodes of deep infection. The femoral component was cemented in 121 cases and cementless in 48. All patients were followed up clinically and radiologically for at least five years.

Results: The two-stage revision was associated with a significant clinical improvement. The reinfection rate was 9% (16/169), of which 11 patients underwent revision surgery and five received chronic suppressive antibiotic treatment. Eight patients required revision due to aseptic loosening and two for periprosthetic fracture. With the numbers available, fixation with or without cement showed no significant differences.

Conclusions: The two-stage revision of an infected hip prosthesis resolved the infection in 91% of the cases. An additional 5% required revision due to aseptic loosening. The surgical outcomes seem to be independent of the femoral component fixation (cemented or cementless).

An acute infection in the first few weeks postoperatively or an acute haematogenous infection in a previously well functioning and well-fixed prosthesis can be managed with open debridement and postoperative intravenous antibiotics for 4 to 6 weeks. Infrequently, elderly patients with a well-fixed prosthesis, absence of drainage, and acceptable pain can be treated with aspiration and chronic oral antibiotic suppression. Treatment of chronic infection requires implant removal and assessment of functional requirements, soft-tissue envelope status, extent of bone loss, and the integrity of the extensor mechanism. Disruption of the extensor mechanism or a poor soft-tissue envelope usually suggests arthrodesis. Definitive resection arthroplasty or above-the-knee amputation is rarely required.

If the decision is made to proceed with reimplantation, a delayed two-stage approach is preferred and strongly recommended. After resection, antibiotic-impregnated spacers are implanted using an antibiotic that will be effective for the offending organism. The most common antibiotics used include a combination of vancomycin and tobramycin in a ratio of 3 g of vancomycin and 3.6 g of tobramycin powder per 40 g batch of bone cement. Most patients are treated with a 4–6 week course of intravenous antibiotics and also receive erythropoeitin alpha to improve their haemoglobin level between the time of resection arthroplasty and reimplantation.

Reimplantation of another prosthesis is performed as soon as it is convenient after the conclusion of the intravenous antibiotics. If there is concern about persistent infection, aspiration or debridement for retrieval of tissue culture, with delayed implantation until culture results are available, can be performed. Most patients are empirically reimplanted based on the appearance of tissues at revision surgery and histological analysis of fresh-frozen tissue samples. Antibiotic-impregnated bone cement is used for prosthesis fixation with the antibiotic choice based on sensitivity tests from the original offending organism(s). Vancomycin and tobramycin are most commonly used in a ratio of 1 to 2 g per batch of bone cement as higher dosages weaken the mechanical strength of the cement.

Currently, most reimplantation prostheses are posterior stabilised or constrained condylar designs. Bone graft is avoided if possible. Postoperatively, antibiotics are continued until results from intraoperative cultures are available and if negative, all antibiotics are discontinued. Positive cultures with the same organism are treated with a 4-week course of intravenous antibiotics. If positive culture results are deemed to be a laboratory contaminant, additional antibiotics are not recommended. Patients are evaluated with annual clinical examinations, erythrocyte sedimentation rate, C-reactive protein level, and plain radiographs. Currently a success rate of 90% is likely with a two-stage technique.

Severe patellar loss, which precludes adequate fixation of another patellar implant, may be treated by patellectomy, retention of the remaining patellar bony shell (resection arthroplasty), gull wing osteotomy, or patellar bone grafting. In contrast to other treatment alternatives, patellar bone grafting uniquely imparts the potential for restoration of patellar bone.

Technique: It is helpful to retain the pseudomeniscus of scar tissue and most of the peripatellar fibrosis tissue to facilitate suture fixation of the tissue flap to the patellar rim. The patellar shell is prepared by removing all fibrous membrane in the crevices of the remaining patellar bone. The tissue flap is created from one of several sources including large flaps of peripatellar fibrotic tissue or a free tissue flap obtained from either the suprapatellar pouch or the fascia lata obtained in the lateral gutter of the knee joint. The tissue flap is sewn to the peripheral patellar rim and peripatellar fibrosis tissue with multiple, nonabsorbable size zero sutures to provide a watertight closure. A small purse string opening is left in one portion of the tissue flap repair to facilitate delivery of bone graft into the patellar defect.

Cancellous autograft is harvested from the metaphyseal portion of the central femur during preparation of the femur for the revision implant. In the absence of locally available cancellous autograft, cancellous allograft bone can be used. The bone graft is prepared by morsellising the bone into small fragments of approximately 5 to 8 mm in height and width to facilitate tight impaction of the bone graft into the patellar shell-tissue flap construct. The bone graft is tightly impacted through the opening of the fascial flap into the patellar bone defect with enough volume so that the height of the final patellar construct has a final height measuring more than 20 mm. The tissue flap is then completely closed to contain the bone graft within the patellar shell. The peripatellar arthrotomy is provisionally repaired with several sutures or towel clips to mould the patellar construct in the femoral trochlea as the knee is placed through the full range of motion. Postoperative rehabilitation is not altered from the usual revision knee arthroplasty protocol.

In contrast with the treatment alternatives of patellectomy or retention of the bony shell, this new surgical procedure uniquely imparts the potential for restoration of patellar bone stock and may improve the functional outcome in these patients by facilitating patellar tracking and improving quadriceps leverage. The procedure is simple to perform and does not require sophisticated instrumentation or a long learning curve. Based on the current satisfactory short-term to mid-term clinical results, this surgical procedure provides an important addition to the armamentarium of the revision knee arthroplasty surgeon.