Trabecular Metal cups for acetabular defects with 50% or less host bone contact

A Registry Study on Acetabular Revisions Using Jumbo Cups: Do We Really Need a More Complex Revision Strategy?

BACKGROUND

The increasing global performance of total hip arthroplasty (THA) has led to a rise in revision surgeries, primarily due to cup failure, with aseptic loosening and periprosthetic infection being common causes. Various techniques and implants, including jumbo cups (JCs), manage residual bone loss post-cup removal, facilitating enhanced surface area for improved host bone contact, and osteointegration. The purpose of the study was to determine the outcomes of acetabular revision arthroplasty using JC implants over a 20-year follow-up period by reporting overall survivorships, complications leading to re-revision, and surgical strategies in re-revision.

METHODS

A cohort study based on a large regional registry was conducted, examining revision THA surgeries utilizing JCs between 2000 and 2020. The study included all the revision acetabular procedures performed with cementless JCs, identified with a diameter ≥ 62 millimeters (mm) in women or ≥ 66 mm in men. All iliac fixation cups were excluded. Data on demographics, revision surgery indications, components, fixation types, causes of failure, and reintervention strategies were collected and analyzed. A total of 541 JCs implanted from January 2000 to December 2020 were evaluated. The most common revision indications were "cup aseptic loosening" (54.5%) and "total aseptic loosening," which included both the cup and stem (32%).

RESULTS

The JC survival rates were 92.5% at 5 years, 85.8% at 10 years, and 81.5% at 15 years. Among the 70 failures, the main causes were "cup aseptic loosening" (40%), "total aseptic loosening" (17.1%), and "septic loosening" (12.8%). Revisions primarily involved acetabular cup revision surgery (54 cases), component explantation (11 cases), or insert or head revision (five cases).

CONCLUSIONS

This registry-based study of JCs in revision THA demonstrates excellent 15-year survival rates and acceptable failure rates. It supports JCs as a viable option, offering relative surgical simplicity compared to alternatives like antiprotrusion cages, bone grafts, and augments.

Long-term outcomes of acetabular impaction grafting with cemented cups and trabecular metal for revision hip arthroplasty: a follow-up study

INTRODUCTION

Revision hip arthroplasty in the presence of complex acetabular deficiencies is challenging. Cement, allograft, reconstruction rings and porous trabecular metal now provide versatile options for acetabular fixation and restoration of acetabular offset. We compare acetabular impaction bone grafting (AIBG) and trabecular metal (TM) cups at long-term follow-up.

METHODS

53 patients who underwent revision hip arthroplasty were retrospectively reviewed from local joint registry data. 36 patients were revised using AIBG and 17 with TM. Median clinical follow-up was 9.57 (2.46-18.72) years and 9.65 (7.22-12.46) years, respectively. 82% of the TM group and 63% of the AIBG group were ⩾ Paprosky 2C. Re-revision was considered failure. Radiographs demonstrating 5 mm of femoral head migration and 5° of acetabular component inclination change were considered loose.

RESULTS

Patients receiving AIBG were younger (68 vs. 74 years) with a longer interval from initial arthroplasty to revision (17 vs. 13 years). Revisions in both groups were indicated most commonly for failed cementing (AIBG 88.9% vs. TM 70.5%). No TM reconstructions underwent re-revision, with only 1 failing at 6.3 years, compared with 9 AIBG re-revisions. When revising for sepsis, 33% of AIBG revisions failed.

CONCLUSIONS

AIBG demonstrated high failure rates at long-term follow-up when compared to TM constructs. We recommend the use of AIBG in small cavitary defects only. We strongly advise against its use in the setting of significant bony defects and for prosthetic joint infection.

Cup-Cage Construct for Treatment of Severe Acetabular Bone Loss in Revision Total Hip Arthroplasty: Clinical and Radiographic Outcomes at a Mean Follow-Up of 7.7 Years

BACKGROUND

Acetabular reconstruction in the context of massive acetabular bone loss is challenging. Achieving implant stability in these situations requires special considerations. The cup-cage construct is a treatment option that addresses this issue. This study evaluates survivorship, complications, and functional outcomes using the cup-cage construct.

METHODS

A total of 131 cup-cage implants (129 patients) were identified from our retrospective review of revision total hip arthroplasties from January 2003 to January 2022. Among these cases, 100 (76.3%) were women, the mean age at the time of surgery was 68 years (range, 29 to 92; SD [SD], 12.4), and the mean follow-up was 7.7 years (range, 0.02 to 20.3; SD, 5.1). Kaplan-Meier survivorship analysis was conducted with failure defined as revision surgery and/or failure of the cup-cage reconstruction.

RESULTS

At a mean follow-up of 7.7 years, the cup-cage construct survivorship due to all-cause failure was 83.9% (95% CI [confidence interval]: 77.6 to 90.2) at 5 years with 88 hips at risk, 74.8% (95% CI: 66.2 to 83.4) at 10 years with 38 hips at risk, and 69.8% (95% CI: 59.4 to 80.2) at 15 years with 11 hips at risk. The survivorship due to failure from aseptic loosening was 96.7% (95% CI: 93.6 to 99.8) at 5 years with 88 hips at risk and 95.5% (95% CI: 91.6 to 99.4) at 10 and 15 years with 38 and 11 hips at risk, respectively. The revision rate for aseptic loosening of the cup and/or cage, infection, dislocation, and aseptic loosening of the femoral stem was 5 of 131 (3.8%), 12 of 131 (9.1%), 10 of 131 (7.6%), and 2 of 131 (1.5%).

CONCLUSIONS

The cup-cage construct is a reliable treatment option for the treatment of various acetabular defects. There are favorable survivorship, clinical, and radiographic outcomes, with a satisfactory complication rate.

AAHKS Surgical Techniques & Technologies Award: Inferior Screw Fixation Decreases Acetabular Component Failure Following Revision Total Hip Arthroplasty

BACKGROUND

Adjunctive screw fixation has been shown to be reliable in achieving acetabular component stability in revision total hip arthroplasty (THA). The purpose of this study was to assess the effect of inferior screw placement on acetabular component failure following revision THA. We hypothesized that inferior screw fixation would decrease acetabular failure rates.

METHODS

We reviewed 250 patients who had Paprosky Type II or III defects who underwent acetabular revision between 2001 and 2021 across three institutions. Demographic factors, the number of screws, location of screw placement (superior versus inferior), use of augments and/or cup-cage constructs, Paprosky classification, and presence of discontinuity were documented. Multivariate regression was performed to identify the independent effect of inferior screw fixation on the primary outcome of aseptic rerevision of the acetabular component.

RESULTS

At a mean follow-up of 53.4 months (range, 12 to 261), 16 patients (6.4%) required re-revision for acetabular loosening. There were 140 patients (56.0%) who had inferior screw fixation, all of whom did not have neurovascular complications during screw placement. Patients who had inferior screws had a lower rate of acetabular rerevision than those who only had superior screw fixation (2.1 versus 11.8%, P = .0030). Multivariate regression demonstrates that inferior screw fixation decreased the likelihood of rerevision for acetabular loosening when compared to superior screw fixation alone (odds ratio: 0.1, confidence interval: 0.03 to 0.5; P = .0071). No other risk factors were identified.

CONCLUSIONS

Inferior screw fixation is a safe and reliable technique to reduce acetabular component failure following revision THA in cases of severe acetabular bone loss.

Evaluation and Management of Acetabular Bone Loss in Revision Total Hip Arthroplasty: A 10-year Update

Acetabular bone loss continues to be one of the most complex and challenging scenarios facing the orthopaedic surgeon. Preoperative planning and classification systems essentially have remained the same, with the Paprosky classification still being the most commonly used. Careful radiological assessment with well-defined criteria can accurately diagnose acetabular bone loss patterns with an associated chronic pelvic discontinuity before surgery. The use of cemented reconstruction techniques has declined, and contemporary practice trends have involved the increasing use of highly porous hemispherical shells in conjunction with modular porous metal augments, which can successfully treat most acetabular revisions. Noncemented treatment options for the management of acetabular bone loss during revision include conventional porous/modular highly porous hemispherical implants, nonmodular highly porous implants with cementable acetabular liners, cup-cage reconstruction, oblong cups, and triflange reconstruction. These options can be combined with modular porous metal augments, structural allografts, impaction grafting, or reconstruction cages. Acetabular distraction is a newer technique for chronic pelvic discontinuity, which is used in conjunction with off-the-shelf revision acetabular shells and modular porous metal augments. This review is an update over the past decade, highlighting studies with mid to long-term follow-up, and presents the advantages, disadvantages, and principles associated with each of the most commonly used reconstructive techniques.

Cup-cage constructs in revision total hip arthroplasty for pelvic discontinuity

Aims

Pelvic discontinuity is a challenging acetabular defect without a consensus on surgical management. Cup-cage reconstruction is an increasingly used treatment strategy. The present study evaluated implant survival, clinical and radiological outcomes, and complications associated with the cup-cage construct.

Methods

We included 53 cup-cage construct (51 patients) implants used for hip revision procedures for pelvic discontinuity between January 2003 and January 2022 in this retrospective review. Mean age at surgery was 71.8 years (50.0 to 92.0; SD 10.3), 43/53 (81.1%) were female, and mean follow-up was 6.4 years (0.02 to 20.0; SD 4.6). Patients were implanted with a Trabecular Metal Revision Shell with either a ZCA cage (n = 12) or a TMARS cage (n = 40, all Zimmer Biomet). Pelvic discontinuity was diagnosed on preoperative radiographs and/or intraoperatively. Kaplan-Meier survival analysis was performed, with failure defined as revision of the cup-cage reconstruction.

Results

The five-year all-cause survival for cup-cage reconstruction was 73.4% (95% confidence interval (CI) 61.4 to 85.4), while the ten- and 15-year survival was 63.7% (95% CI 46.8 to 80.6). Survival due to aseptic loosening was 93.4% (95% CI 86.2 to 100.0) at five, ten, and 15 years. The rate of revision for aseptic loosening, infection, and dislocation was 3/53 (5.7%), 7/53 (13.2%), and 6/53 (11.3%), respectively. The mean leg length discrepancy improved (p < 0.001) preoperatively from a mean of 18.2 mm (0 to 80; SD 15.8) to 7.0 mm (0 to 35; SD 9.8) at latest follow-up. The horizontal and vertical hip centres improved (p < 0.001) preoperatively from a mean of 9.2 cm (5.6 to 17.5; SD 2.3) to 10.1 cm (6.2 to 13.4; SD 2.1) and 9.3 cm (4.7 to 15.8; SD 2.5) to 8.0 cm (3.7 to 12.3; SD 1.7), respectively.

Conclusion

Cup-cage reconstruction provides acceptable outcomes in the management of pelvic discontinuity. One in four constructs undergo revision within five years, most commonly for periprosthetic joint infection, dislocation, or aseptic loosening.

Does Using Highly Porous Tantalum in Revision Total Hip Arthroplasty Reduce the Rate of Periprosthetic Joint Infection? A Systematic Review and Meta-Analysis

BACKGROUND

Studies suggest tantalum (Ta) implants may have inherent antibacterial properties. However, there is no consensus regarding the effectiveness of Ta in preventing periprosthetic joint infection (PJI) after revision total hip arthroplasty (rTHA).

METHODS

We searched 5 main databases for articles reporting the rate of PJI following rTHA using Ta implants from inception to February 2022. The PJI rates of the Ta group were meta-analyzed, compared with the control group, and represented as relative risks (RRs) in forest plots.

RESULTS

We identified 67 eligible studies (28,414 joints) for assessing the prevalence of PJI following rTHA using Ta implants. Among these studies, only 9 compared the Ta implant group with a control group. The overall PJI rate following rTHA using Ta implants was 2.9% (95% confidence interval [CI]: 2.2%-3.8%), while it was 5.7% (95% CI = 4.1%-7.8%) if only septic revisions were considered. Comparing the Ta and control groups showed a significantly lower PJI rate following all-cause rTHA with an RR = 0.80 (95% CI = 0.65-0.98, P < .05). There was a trend toward lower reinfection rates in the Ta group after rTHA in septic cases, although the difference was not statistically significant (RR = 0.75, 95% CI = 0.44-1.29, P = .30).

CONCLUSIONS

Ta implants are associated with a lower PJI rate following all-cause rTHA but not after septic causes. Despite positive results, the clinical significance of Ta still remains unclear since the PJI rate was only reduced by 20%.

LEVEL OF EVIDENCE

IV.

Forged to heal: The role of metallic cellular solids in bone tissue engineering

Metallic cellular solids, made of biocompatible alloys like titanium, stainless steel, or cobalt-chromium, have gained attention for their mechanical strength, reliability, and biocompatibility. These three-dimensional structures provide support and aid tissue regeneration in orthopedic implants, cardiovascular stents, and other tissue engineering cellular solids. The design and material chemistry of metallic cellular solids play crucial roles in their performance: factors such as porosity, pore size, and surface roughness influence nutrient transport, cell attachment, and mechanical stability, while their microstructure imparts strength, durability and flexibility. Various techniques, including additive manufacturing and conventional fabrication methods, are utilized for producing metallic biomedical cellular solids, each offering distinct advantages and drawbacks that must be considered for optimal design and manufacturing. The combination of mechanical properties and biocompatibility makes metallic cellular solids superior to their ceramic and polymeric counterparts in most load bearing applications, in particular under cyclic fatigue conditions, and more in general in application that require long term reliability. Although challenges remain, such as reducing the production times and the associated costs or increasing the array of available materials, metallic cellular solids showed excellent long-term reliability, with high survival rates even in long term follow-ups.

Outcomes of Impaction Bone Grafting in the Management of Acetabular Defects with the Use of Uncemented Acetabular Cups: Do Autografts and Irradiated Femoral Head Allografts Integrate?

Introduction

Acetabular impaction bone grafting (AIBG) has been used widely to reconstruct acetabular defects in complex primary and revision cases. The aim of this study was to look at the outcomes AIBG using either frozen irradiated femoral head allografts or autografts with uncemented acetabular cups.

Method

We retrospectively reviewed 38 patients who had AIBG and uncemented cup reconstruction of the acetabulum performed between 2008 and 2021 for complex primary and revision surgery. Graft incorporation, radiological loosening and cup migration were evaluated in follow-up X-rays.

Result

There were 24 complex primary and 14 revision total hip arthroplasty. Autografts were used in 10 hips with smaller defects, while 28 hips with larger defects required frozen irradiated femoral head allografts. Using Paprosky classification to evaluate acetabular defects; 8 patients were classified as 2A, 12 as 2B, 7 as 2C, 8 as 3A and 3 as 3B. The Kaplan-Meier survival rate for AIBG with uncemented cups in our series is 89.70% in 10 years. Acetabular cup position was anatomically restored in all autograft AIBG cases and in 25 out of 28 in the allograft group. The mean pre-operative Oxford Hip Score (OHS) was 19 (range 10-24) and post-operative OHS was 39 (range 21-48) (p < 0.001).

Conclusions

The mid- to long-term results for AIBG and uncemented acetabular cups is good. With newer and more porous uncemented cups especially revision cups, it may serve as an extended indication to achieve solid fixation together with AIBG technique in managing acetabular defects of ≤ 3A.

Periprosthetic acetabular fractures as a complication of total hip arthroplasty

Periprosthetic acetabular fractures are rare but potentially devastating complications of total hip arthroplasty. As the number of total hip arthroplasties performed annually increases, so has the incidence of periprosthetic fractures, with the topic being spotlighted more frequently in the orthopaedic community. There is a particular sparsity of literature regarding periprosthetic acetabular fractures, with periprosthetic femoral fractures after total hip arthroplasty being traditionally far more commonly reported. This article aims to provide an up-to-date review of the epidemiology, risk factors, diagnostic challenges, classifications, and management strategies for periprosthetic acetabular fractures after total hip arthroplasty.

The modern Burch-Schneider antiprotrusio cage for the treatment of acetabular defects: is it still an option? A systematic review

BACKGROUND

A number of papers have been published about the clinical performance of modern rough-blasted titanium Burch-Schneider antiprotrusio cages (BS-APCs) for the treatment of acetabular bone defects. However, no systematic review of the literature has been published to date.

METHODS

The US National Library of Medicine (PubMed/MEDLINE), EMBASE, and the Cochrane Database of Systematic Reviews were queried for publications using keywords pertinent to Burch-Schneider antiprotrusio cage, revision THA, and clinical outcomes.

RESULTS

8 articles were found to be suitable for inclusion in the present study in which 374 cases (370 patients) had been treated with modern BS-APCs. Most acetabular bone defects were type 3 according to the Paprosky classification (type 2C: 18.1%, 3A: 51%, and 3B: 28.9%). The overall re-revision rate for the 374 acetabular reconstructions with modern BS-APCs was 11.5% (43 cases). The short-term survival rate of the modern BS-APC construct was 90.6% (339 out of 374 cases), while the mid-term survival rate was 85.6% (320 out of 374 cases), and the long-term survival rate 62% (54 out of 87 cases). The most common reasons for revision were aseptic loosening (5.6%), periprosthetic joint infection (3.8%), dislocation (2.7%), and acetabular periprosthetic fracture (1.9%).

CONCLUSIONS

There was moderate quality evidence to show that the use of modern rough blasted titanium BS-APCs in cases of acetabular bone loss has an unacceptably high failure rate (38%). Given that antiprotrusio cages do not provide any biological fixation, we would not recommend the routine use of modern BS-APCs in complex revision THA cases. By contrast, the satisfactory short- to mid-term outcome of modern BS-APCs in combination with their low cost compared to highly porous acetabular implants, make us feel that BS-APCs might still be used in selected elderly or low-demand patients without severe superomedial acetabular bone loss.

Outcomes of novel 3D-printed fully porous titanium cup and a cemented highly cross-linked polyethylene liner in complex and revision total hip arthroplasty

INTRODUCTION

A novel fully porous acetabular titanium shell has been designed to reduce stiffness mismatch between bone and implant and promote osseointegration in complex (cTHA) and revision total hip arthroplasty (rTHA). A highly cross-linked polyethylene (XLPE) liner is cemented within the cup to reduce wear rates and increase survivorship. This study reported the outcomes of an XLPE liner cemented into a novel 3D-printed fully porous cup in cTHA and rTHA.

METHODS

Presented was a multicenter retrospective review of 40 patients (6 cTHA and 34 rTHA) who underwent THA with a fully porous titanium acetabular cup and cemented XLPE liner. Data were collected on demographics, surgical information, outcomes, including osseointegration and migration and implant survivorship.

RESULTS

On average, patients were 71.42 ± 9.97 years old and obese (BMI: 30.36 ± 6.88 kg/m²) and were followed up for a mean time of 2.21 ± 0.77 years. Six patients underwent cTHA and 34 patients underwent rTHA. The mean hospital length of stay was 5.34 ± 3.34 days. Three (7.5%) 90-day readmissions were noted. Harris Hip Scores improved, on average, from 53.87 ± 12.58 preoperatively to 83.53 ± 12.15 postoperatively (P<0.001). One case of acetabular shell aspetic loosening with migration was noted. Thirty-nine of the 40 acetabular components were fully osseointegrated without migration. Two patients underwent re-revision surgery for PJI and one patient received acetabular shell+liner re-revision due to aseptic loosening. Kaplan-Meier analysis showed an all-cause revision-free survival rate of 95.0% at 6 months and 1 year, and 92.0% at 4-years. Aseptic acetabular cup, liner dislocation/loosening, and fracture-free survival was 100% at 6 months and 1-year, and 97.1% at 2 years.

CONCLUSION

The combined use of a novel 3D-printed fully porous titanium acetabular shell and cemented XLPE acetabular liner yielded excellent rates of osseointegration, and all-cause and acetabular aseptic loosening survivorship at a minimum 1-year follow-up. Further long-term studies are needed to assess the longevity of this construct.

Direct Anterior Cup-Half Cage for Revision and Complex Primary Total Hip Arthroplasty: Surgical Technique

As surgeons' comfort with the direct anterior approach (DAA) for total hip arthroplasty continues to increase, there is a growing interest in performing complex surgeries through this approach. Acetabular bone loss and/or pelvic discontinuity in the primary or revision setting often requires specialized implants such as a cup-cage construct. We describe our surgical technique for implanting modified cup-half cages through the DAA and show 2 case examples of how this technique was utilized in the setting of complex acetabular bone loss. In our experience, this is an effective method for complex total hip arthroplasty, with the potential added benefits of the DAA of reduced soft-tissue dissection, direct measurement of leg length, and ease of fluoroscopic navigation for implant positioning.

Anatomic acetabular reconstruction with femoral head autograft for developmental dysplasia of the hip (DDH) with a minimum follow-up of 10 years

BACKGROUND

DDH with coxarthrosis causes significant deformity and bone deficiency. Various reconstructive techniques have been proposed to treat developmental dysplasia of the hip. However, the existing literature has not yet reached a consensus on the best technique regarding long-term survival.

OBJECTIVES

This study aims to evaluate the long-term survival of uncemented hydroxyapatite (HA) coated acetabular components augmented with a femoral head autograft.

METHODS

We retrospectively reviewed the cases of 31 hips in 29 patients (24 female, 5 male, mean age 45.06 years) treated with HA-coated cementless components and femoral head autograft between 2000-2008 with a minimum follow-up of 10 years. Graft resorption, cup loosening and the anatomical hip centre were determined. Functional outcomes were calculated using the Harris Hip Scoring system. The survival of the acetabular component was evaluated using the Kaplan-Meier method.

RESULTS

In 24 hips (77,4%), we reconstructed the hip centre anatomically. The remaining cups had variable deviations from the anatomical rotation centre. Only one patient required revision due to loosening. Survival analysis revealed 96.8% survival at 10 years. The mean Harris Hip Score was 39.23 preoperatively and 84.77 at final follow-up. There was no statistical correlation between revision and any of the measured parameters.

DISCUSSION

Acetabular reconstruction with a femoral head autograft allows for anatomical cup positioning, early structural support and increases bone stock for future revisions. Although our prior cemented cup study showed that anatomical cup orientation is critical, this study demonstrated the absence of a correlation between implant failure and cup positioning, suggesting that HA-coated cementless cups are more stable and forgiving.

CONCLUSIONS

HA-coated acetabular cups augmented with femoral head autograft provided long-term, reliable and durable cup fixation in dysplastic hips of young adults.

Acetabular Revision Surgery with Tantalum Trabecular Metal Acetabular Cup for Failed Acetabular Cage Reconstruction with Bone Allografts: A Retrospective Study with Mid- to Long-Term Follow-Up

Background: Acetabular cage reconstruction with bone allografts is among the successful strategies to deal with massive acetabular bone loss. However, the nonbiological fixation nature of cages can compromise long-term success. Tantalum trabecular metal acetabular cups (TM cups) have been used in acetabular revision surgery because of their increased initial stability and good bone ingrowth features. This study was performed to determine whether the bone stock of the acetabulum is enough to support a hemispheric TM cup after failed cage reconstruction with bone allografts. Methods: We retrospectively reviewed patients who received acetabular revision surgery with TM cups after failed cage reconstruction with bone allografts from 2006 to 2017. There were 12 patients (5 males and 7 females) included in this study, with a mean age of 61.5 years (38 to 81) at the time of re-revision surgery. The mean follow-up after re-revision surgery was 8.6 years (2.6 to 13.3). The endpoint was defined as the aseptic loosening of the TM cup and reoperation for any causes. The change in bone stock of the acetabulum between index revision and re-revision was assessed according to the Gross classification for acetabular bone loss. Results: One patient died after eight years of follow-up of a cause not related to hip surgery. Two patients received two-stage revision arthroplasty due to PJI after 3.2 and 9.4 years of follow-up, respectively. The bone stock of the acetabulum was significantly improved between index revision and re-revision surgery (p < 0.0001). The Kaplan−Meier survivorship was 100% with aseptic loosening as the endpoint and 90% and 75% at five- and ten-year follow-up, respectively, with reoperation for any reason as the endpoint. Even cage reconstruction with bone allografts will fail eventually, and the bone stock of the acetabulum will improve after union and incorporation between host bone and allografts. The restored bone stocks will facilitate further revision surgery with hemispheric TM cups. The biological fixation between host bone and tantalum trabecular metal can provide longstanding stability of the TM cup. Conclusions: The results of our study offer a viable option for patients with failed cage reconstruction with bone allografts.

Uncemented Cups and Impaction Bone Grafting for Acetabular Bone Loss in Revision Hip Arthroplasty: A Review of Rationale, Indications, and Outcomes

Total hip arthroplasty (THA) is increasingly performed in young patients and the number of revisions is estimated to rise over time. Acetabular osteolysis and bone loss are frequently encountered during revision and may be classified and treated in different ways. Impaction bone grafting (IBG) with morselized allograft offers a viable option. IBG was introduced over 40 years ago in combination with cemented cups, and is also used with uncemented cups. The impacted bone chips act as a void filler to restore bone stock; once incorporated they are substituted by host bone. Surgery entails assessment of the defect, acetabular preparation, preparation of the morselized graft, impaction of the graft, and cup implantation. Satisfactory medium- and long-term results have now been reported in most studies. With the advent of high-porosity cups, indications have been extended, enhancing the potential of IBG, in which primary stability of the cup to the host bone is essential for a successful procedure. Synthetic bone substitutes have also been used in combination with allogenic grafts and may extend the original technique for which long-term studies are warranted.

Do trabecular metal cups achieve better results when compared to hemispherical porous titanium cups in acetabular revision surgery?

BACKGROUND

Trabecular metal (TM) cups were introduced in order to achieve better ingrowth and stability of the cup in acetabular revision surgery. As their use has evolved over time, we have queried whether TM cups would improve results in terms of the rate of aseptic loosening when compared to historical uncemented porous titanium cups used in revision surgery for acetabular bone loss in Hospital La Paz (Madrid, Spain).

METHODS

We retrospectively reviewed 197 acetabular revisions performed between 1991 and 2015. Titanium cups were used in 81 cases and TM cups in 116. The mean follow-up was 8.1 years (range 1-15); 12.0 ± 7.8 for titanium group and 5.4 ± 3.1 for TM group. The most common reason for revision was aseptic loosening. A Kaplan-Meier analysis was used to determine the survival of the cup, with radiological failure and re-revision due to aseptic loosening as the endpoints. Cox multivariate regression analyses were performed to assess different risk factors for failure.

RESULTS

1 TM cup and 1 titanium cup were re-revised due to aseptic loosening (p = 0.61). Radiological cup loosening was observed in 4 TM cups and 2 titanium cups (p = 1.0). At 6 years, the probability of not having radiological cup loosening was 97.4% (95% CI, 93.9-100) for the titanium cups and 95.1% for the TM cups (95% CI, 90.1-99.9) (p = 0.59). Another 5 cups were re-revised due to dislocation. Hips with a greater Paprosky defect showed a higher risk of loosening (p < 0.05, hazard risk (HR) 3.04; 95% CI, 0.97-9.54).

CONCLUSIONS

This study shows there was no significant difference in re-revision due to aseptic loosening or radiological loosening between titanium and TM cups in revision surgery for acetabular bone loss. Both types of cups demonstrate excellent results with a low failure rate and minimal complications.

Retention of Monoblock Femoral Components Using a Dual Mobility Bearing: A Report of 3 Cases

CASE

We present the results of 3 cases followed up for a minimum period of 4.5 years of revision total hip arthroplasty using a metal acetabular shell with retention of a well-fixed monoblock femoral component by inserting a dual mobility polyethylene bearing onto the femoral head in situ.

CONCLUSION

This is the first case series to use this technique to address acetabular osteolysis and avoid removing a well-fixed monoblock femoral component at the time of revision surgery.

Fixation Stability of Uncemented Acetabular Cups With Respect to Different Bone Defect Sizes

BACKGROUND

In total hip arthroplasty, acetabular press-fit cups require a proper bone stock for sufficient primary implant fixation. The presence of acetabular bone defects compromises the primary fixation stability of acetabular press-fit cups. The aim of the present study is to determine the fixation stability of a cementless acetabular cup regarding standardized bone defects in an experimental setup.

METHODS

An acetabular defect model was developed and transferred to a biomechanical cup-block model. The lack of superior cup coverage was divided into 4 stages of superior rim loss (33%, 50%, 67%, and 83%) in the anterior-posterior direction and into 4 stages of mediolateral wall absence (11%, 22%, 33%, and 50%). This resulted in 11 different defect cavities, which were compared to the intact cavity in push-in and lever-out tests of one press-fit cup design (56 mm outer diameter). Thereby, push-in force, lever-out moment, lever-out angle, and interface stiffness were determined.

RESULTS

The determined lever-out moments range from 15.53 ± 1.38 Nm (intact cavity) to 1.37 ± 0.54 Nm (83%/50% defect). Smaller defects (33%/11%, 33%/22%, and 50%/11%) reduce the lever-out moments by an average of 33.9% ± 2.8%.

CONCLUSION

The lack of mediolateral acetabular coverage of 50% was assessed as critical for cementless cup fixation, whereby the contact zone between implant and bone in the defect is lost. A lack of 20% to 30% mediolateral coverage appears to be acceptable for press-fit cup fixation in the presence of primary stability. A defect of 50%/50% was identified as the threshold for using additional fixation methods.

Acetabulum Cup Stability in an Early Weight-Bearing Cadaveric Model of Geriatric Posterior Wall Fractures

BACKGROUND

Primary total hip arthroplasty (THA) has been suggested for posterior wall (PW) fractures with unfavorable features in the geriatric population. There is a paucity of studies reporting on postoperative protocols for primary THA after PW fractures. The purpose of this study was to test the biomechanical effect of immediate assisted weight-bearing on acetabulum THA cup fixation in an osteoporotic PW fracture model.

METHODS

Computed tomography scans of 18 geriatric PW fractures (mean age, 77 ± 8 years) were used to generate representative PW fracture. This fracture pattern, comprising 50% of the PW and 25% of the acetabulum rim, was then created in 6 female cadaveric pelves. A multihole acetabulum THA cup was implanted with line-to-line reaming and fixed with four 5-mm screws. The pelves were cyclically loaded to up to 1.8× body weight (BW) in the intact form, after fracture creation and fracture fixation. Optical markers were used to determine acceptable cup motion of less than 150 μm.

RESULTS

Five specimens withstood 3.6× BW loading after implantation and before fracture creation. At 1.8× BW load, cup motion was nonfractured: 50 ± 24 µm (range, 5-128 µm), fractured with no fixation: 37 ± 22 µm (range, 8-74 µm), or fractured with fixation: 62 ± 39 µm (range, 5-120 µm) (P = 0.0097). Cup motion was <150 µm for all groups.

CONCLUSION

This study supports the practice of allowing immediate assisted weight-bearing in patients undergoing THA with PW fractures involving up to 50% of the PW and up to 25% of the acetabular rim, with or without fixation of the PW fragment.

Reconstruction for pelvic discontinuity and massive acetabular defects

OBJECTIVE

The acetabular reconstruction with massive acetabular defects and pelvic discontinuity is a complex surgery with important difficulties for the orthopaedic surgeon. The objective of this study is to show the short and midterm results of the acetabular revision with the Cup-Cage construct in a consecutive serie of cases.

MATERIAL AND METHODS

Retrospectively we reviewed 22 consecutive patients with massive acetabular defects (8 Paprosky IIIa and 9 IIIB); 5 pelvic discontinuities; 2 pelvic fractures during the implantation of primary artroplasty, and one pelvic pseudoarthrosis. All were reoperated with a trabecular metal acetabular component and a Cup-Cage. We did clinical and radiological follow-up to detect machanical failures and loosening of the implant.

RESULTS

With a middle follow-up of 45.06 months (12-73 months) we did not see any radiographic failure of the implant (component migration, osteolysis neither rupture of the implant or screws). The complications (13,63%) included one recurrent luxation, one infection and one recurrent subluxation. The Merle d'Aubigné-Postel score improved from 6.91 to 14.36 and the punctuation in the range of motion from 2.91 to 4.36 on average of the values preoperatively and postoperatively respectively and improvement in Harris Hip Score 30 (16-55) to 72 (40-90) in the latest follow up.

CONCLUSION

The acetabular reconstruction with the Cup-Cage system is a valid alternative for the reconstruction of massive acetabular defects (Paprosky type IIIA and IIIB) and pelvic discontinuities offering good results at short and midterm follow-up.

Reconstruction of failed acetabular component in the presence of severe acetabular bone loss: a systematic review

Acetabular revision especially in the presence of severe bone loss is challenging. There is a paucity of literature critiquing contemporary techniques of revision acetabular reconstruction and their outcomes. The purpose of this study was to systematically review the literature and to report clinical outcomes and survival of contemporary acetabular revision arthroplasty techniques (tantalum metal shells, uncemented revision jumbo shells, reinforced cages and rings, oblong shells and custom-made triflange constructs). Full-text papers and those with an abstract in English published from January 2001 to January 2016 were identified through international databases. A total of 50 papers of level IV scientific evidence, comprising 2811 hips in total, fulfilled the inclusion criteria and were included. Overall, patients had improved outcomes irrespective of the technique of reconstruction as documented by postoperative hip scores. Our pooled analysis suggests that oblong cups components had a lower failure rate compared with other different materials considered in this review. Custom-made triflange cups had one of highest failure rates. However, this may reflect the complexity of revisions and severity of bone loss. The most common postoperative complication reported in all groups was dislocation. This review confirms successful acetabular reconstructions using diverse techniques depending on the type of bone loss and highlights key features and outcomes of different techniques. In particular, oblong cups and tantalum shells have successful survivorship.

Radiolucency around highly porous sockets and hydroxyapatite-coated porous sockets in total hip arthroplasty for hip dysplasia

Studies over the past decade have reported that the use of highly porous sockets in total hip arthroplasty (THA) results in osseointegration and long-term implant stability. However, some reports have raised concerns regarding radiographic evidence of poor osseointegration with features of fibrous tissue ingrowth. The purpose of this study was to compare clinical and radiographic assessments of highly porous sockets with those of hydroxyapatite (HA)-coated porous sockets in THA for hip dysplasia (DDH) at least 1 year after surgery. A total of 127 patients (136 hips) were recruited for the study. Of these, 94 patients (101 hips) received highly porous sockets with clustered screws, while 33 patients (35 hips) received HA-coated porous sockets with clustered screws. There was no difference in clinical outcomes between the two types of sockets. All HA-coated porous sockets were radiographically stable, without radiolucent lines. Fifteen hips had radiolucent lines in two or three DeLee and Charnley zones, accompanied by sclerotic lines along the circumferences of the highly porous sockets. A significant difference in the height of the preoperative osteophyte of the anterior acetabular wall was observed between 86 hips with one or no radiolucent lines and 15 hips with two or three radiolucent lines. In cases of DDH with atrophic bone remodeling pattern, highly porous sockets with multiple screws may be used, while HA-coated porous sockets with clustered screws result in better sealing of the bone–component interface.

Cup-cage reconstruction for severe acetabular bone loss and pelvic discontinuity: Mid-term Results of a Consecutive Series of 35 Cases

AIMS

Severe acetabular bone loss and pelvic discontinuity (PD) present particular challenges in revision total hip arthroplasty. To deal with such complex situations, cup-cage reconstruction has emerged as an option for treating this situation. We aimed to examine our success in using this technique for these anatomical problems.

PATIENTS AND METHODS

We undertook a retrospective, single-centre series of 35 hips in 34 patients (seven male, 27 female) treated with a cup-cage construct using a trabecular metal shell in conjunction with a titanium cage, for severe acetabular bone loss between 2011 and 2015. The mean age at the time of surgery was 70 years (42 to 85) and all patients had an acetabular defect graded as Paprosky Type 2C through to 3B, with 24 hips (69%) having PD. The mean follow-up was 47 months (25 to 84).

RESULTS

The cumulative five-year survivorship of the implant with revision for any cause was 89% (95% confidence interval (CI) 72 to 96) with eight hips at risk. No revision was required for aseptic loosening; however, one patient with one hip (3%) required removal of the ischial flange of the cage due to sciatic nerve irritation. Two patients (6%; two hips) suffered from hip dislocation, whereas one patient (one hip) required revision surgery with cement fixation of a dual-mobility acetababular component into a well-fixed cup-cage construct. Two patients (6%; two hips) developed periprosthetic infection. One patient was successfully controlled with a two-stage revision surgery, while the other patient underwent excision arthroplasty due to severe medical comorbidities. For the whole series, the Harris Hip Score significantly improved from a mean of 30 (15 to 51) preoperatively to 71 (40 to 89) at the latest follow-up (p < 0.001).

CONCLUSION

Our findings suggest that cup-cage reconstruction is a viable option for major segmental bone defects involving the posterior column and PD. It allows adequate restoration of the acetabulum centre with generally good stability and satisfactory postoperative function. Instability and infection remain drawbacks in these challenging revision cases. Cite this article: Bone Joint J 2018;100-B:1442-48.

Long-Term Results of Acetabular Reconstruction Using Ganz Acetabular Rings

BACKGROUND

Our study examines the long-term results of acetabular reconstruction using the Ganz acetabular reinforcement ring (GRR) in total hip arthroplasty.

METHODS

Between 1998 and 2001, 135 hips (119 revision and 16 primary arthroplasties) were consecutively implanted with a GRR at our hospital. The average age was 65 years (range, 26-90). Clinical and radiographic evaluations were carried out. Long-term survivorship was estimated using a competing risks analysis, and multivariate survivorship using Cox regression model was used to identify risk factors for implant failure.

RESULTS

At a mean follow-up of 16 years (range, 15-18), 3 patients were lost to follow-up and 19 had implant failure: 4 aseptic loosenings without re-revision, 4 septic, and 11 aseptic re-revisions. Survival was estimated at 86% after 16 years (95% confidence interval [CI], 78.5%-90.9%) using radiographic loosening or revision for any reason as the end point. Using aseptic loosening as the end point, the survival was estimated at 91.2% after 16 years (95% CI, 84.5%-95.0%). Multivariate analysis revealed that age at surgery was a significant risk factor for failure of the GRR. With acetabular revision or loosening as the end point, patients ≤60 years had 71.6% (95% CI, 53%-82.8%) and older patients had 92.2% (95% CI, 84%-96.2%) probability of implant survival after a mean 16-year follow-up. The median Harris Hip Scores and Western Ontario and McMaster Universities Osteoarthritis Index scores were 77 and 64.5, respectively, and mean Numerical Pain Rating Scale score was 1.6 at final follow-up.

CONCLUSION

Our long-term study showed acceptable survival and functional results using the GRR in older patients, while young patients had less favorable survival.

Revision Total Hip Arthroplasty for Paprosky Type III Acetabular Defect With Structural Allograft and Tantalum Trabecular Metal Acetabular Cup

There are several surgical options for addressing Paprosky type III acetabular defects during revision total hip arthroplasty. In physiologically young and active patients, using structural bone graft to restore bone defects and provide adequate initial support for the revision acetabular component is one such option. This study reports the mid-term results of using a structural allograft accompanied by a trabecular metal-coated hemispherical cup for Paprosky type III defects. A retrospective analysis was performed of the data collected for 20 consecutive hips in 20 patients (mean age, 56.2 years; range, 43-68 years) with minimum 3-year follow-up (mean, 5.4 years; range, 3.3-10.3 years) who had a structural allograft accompanied by a trabecular metal-coated hemispherical cup for Paprosky type III defects. Only 1 hip had cup migration, which was less than 3 mm in vertical and less than 5° in inclination and recognized as loosening without symptoms. All grafts showed good incorporation with trabecular bridging over the graft and host bone. The mean modified Harris hip score showed significant improvement, from 29.7 (range, 11-52) preoperatively to 84.1 (range, 77-91) at the latest follow-up (P<.05). The use of a structural allograft combined with a tantalum trabecular metal acetabular cup in acetabular revision for Paprosky type III defects had a satisfactory mid-term clinical result. This is a viable option for patients with large acetabular shelf defects. [Orthopedics. 2018; 41(6):e861-e867.].

Tritanium Acetabular Cup in Revision Hip Replacement: A Six to Ten Years of Follow-Up Study

BACKGROUND

The use of highly porous acetabular components has shown to produce good results in revision acetabular surgery. Their surface characteristics enhance initial fixation and bone ingrowth which are prerequisites for adequate osseointegration. The purpose of this study is to analyze the mid-term to long-term survival, clinical and radiological outcomes using the Tritanium cup (Stryker, Mahwah, NJ) in revision hip surgery.

METHODS

This is a retrospective review of all patients who underwent acetabular revision surgery using "Tritanium revision cup" between April 2007 and November 2010 at our institution. Sixty-two patients were included with a mean age of 67.5 years (32-86). According to Paprosky classification, 10 patients had type I defect, 8 had type IIA, 27 had type IIB, 7 had type IIC, and 10 suffered from type IIIA defect. A Kaplan-Meier analysis was used to determine the survival of the cup. Functional outcomes were assessed using Oxford Hip Score. Plain radiographs were performed to assess implant fixation and osseointegration.

RESULTS

The acetabular cup aseptic survivorship was 98.4% at a mean follow-up of 87.6 months. The mean Oxford Hip Score improved from 14.5 (3-31) preoperatively to 38.5 (12-48) at the final follow-up. Two cups were revised (3.2%): 1 for aseptic loosening and 1 for infection.

CONCLUSION

Tritanium revision acetabular cup has shown excellent mid-term to long-term clinical and radiographic results with low failure rate and minimal complications. Longer term follow-up would be of value to assess the ongoing survival of this implant construct.

Additive manufacturing technique-designed metallic porous implants for clinical application in orthopedics

Traditional metallic scaffold prostheses, as vastly applied implants in clinical orthopedic operations, have achieved great success in rebuilding limb function. However, mismatch of bone defects and additional coating requirements limit the long-term survival of traditional prostheses. Recently, additive manufacturing (AM) has opened up unprecedented possibilities for producing complicated structures in prosthesis shapes and microporous surface designs of customized prostheses, which can solve the drawback of traditional prostheses mentioned above. This review presents the most commonly used metallic additive manufacturing techniques, the microporous structure design of metallic scaffolds, and novel applications of customized prostheses in the orthopedic field. Challenges and future perspectives on AM fabricated scaffolds are also summarized.

Mid-Term Results of Graft Augmentation Prosthesis II Cage and Impacted Allograft Bone in Revision Hip Arthroplasty

BACKGROUND

Several techniques have been described for management of severe acetabular bone defects during revision hip surgery including reconstructive cages. The purpose of this study is to analyze the survival and the mid-term clinical and radiological outcome using the Graft Augmentation Prosthesis (GAP II cage) (Stryker Orthopaedics, Mahwah, NJ) in addition to impaction grafting for acetabular defects in revision hip surgery.

METHODS

This is a retrospective review of all patients who underwent acetabular revision hip replacement using GAP II cage and impaction bone grafting between 2009 and 2013 at our institution. Twenty-six patients were included with a mean age of 71 years (49-91). According to Paprosky classification, 2 patients had type IIB defect, 4 had type IIC, and 12 had type IIIA, while 8 suffered from type IIIB defect. The clinical outcome was assessed using Oxford Hip Score. Plain radiographs were used to assess preoperative bone loss, postoperative implant migration, and the incorporation of the bone graft to host bone.

RESULTS

The average Oxford Hip Score improved from 11.3 (2-22) preoperatively to 32.2 (20-48) postoperatively. The revision free survivorship of this construct was 100% at mean follow-up of 49 months (30-78). Three hips had radiological failure of the implant with no clinical consequences.

CONCLUSION

The use of GAP II cage with impaction bone grafting to reconstruct severe acetabular defects had encouraging mid-term results with low failure rate. Graft incorporation with restoration of bone stock may be beneficial should further revision surgery be needed.

Do dual-mobility cups cemented into porous tantalum shells reduce the risk of dislocation after revision surgery?

Background and purpose - Dual-mobility cups (DMCs) reduce the risk of dislocation and porous tantalum (TM) shells show favorable osseointegration after acetabular revision surgery, yet the combination of these implants has not been studied. We hypothesized that (1) cementing a DMC into a TM shell decreases the risk of dislocation; (2) DMCs cemented into TM shells are not at greater risk of re-revision; (3) liberation of tantalum ions is marginal after use of this combined technique. Patients and methods - We investigated the outcome in 184 hips (184 patients) after acetabular revision surgery with TM shells, fitted either with DMCs (n = 69), or with standard poly-ethylene (PE) liners (n = 115). Chart follow-up was complete for all patients, and the occurrence of dislocations and re-revisions was recorded. 20 were deceased, 50 were unable to attend follow-up, leaving 114 for assessment of hip function after 4.9 (0.5-8.9) years, radiographs were obtained in 99, and tantalum concentrations in 84 patients. Results - 1 patient with a DMC had a dislocation, whereas 14 patients with PE liners experienced at least 1 dislocation. 11 of 15 re-revisions in the PE group were necessitated by dislocations, whereas none of the 2 re-revisions in the DMC group was performed for this reason. Hence, dislocation-free survival after 4 years was 99% (95% CI 96-100) in the DMC group, whereas it was 88% (CI 82-94, p = 0.01) in the PE group. We found no radiographic signs of implant failure in any patient. Mean tantalum concentrations were 0.1 µl/L (CI 0.05-0.2) in the DMC group and 0.1 µg/L (CI 0.05-0.2) in the PE group. Interpretation - Cementing DMCs into TM shells reduces the risk of dislocation after acetabular revision surgery without jeopardizing overall cup survival, and without enhancing tantalum release.

Radiographic evaluation of 19 patients with Paprosky 3A and 3B submitted to acetabular review with trabecular metal wedge

Objective

This study is aimed at evaluating the fixation of trabecular metal wedges in patients who underwent revision of total hip arthroplasty with large acetabular bone defects.

Methods

The radiographs of 19 patients (21 hips), who underwent revision of total hip arthroplasty using trabecular metal wedges from September 2010 to December 2014 were evaluated. This study included only cases of Paprosky 3A and 3B. Preoperative and postoperative images were analyzed. Non-fixation of the implant was defined by the presence of angular variation of the component higher 10 degrees or displacement greater than 6 mm. Patients with follow-up times of less than 24 months or who did not attend the last two appointments were excluded from the study.

Results

The mean follow-up time was 39.4 months (25–61). Fixation was achieved in all cases despite its complexity. There was only one case of dislocation that was treated with open reduction. One case developed infection, and was surgically approached on two occasions, with extensive debridement and intravenous antibiotics following protocol, with good evolution.

Conclusion

The implanted trabecular metal wedges showed excellent results in the short- and medium-term and may represent another option in the reconstruction of large acetabular defects, sometimes replacing bone reconstruction that uses bone tissue banks or autologous graft.

Determination of structural femoral head allograft viability and integrity with a novel diagnostic tool: SPECT/CT. A preliminary study

OBJECTIVE

To evaluate the viability and integrity of fresh frozen bulk femoral head allografts obtained from the institutional bone bank that were used to reconstruct severe acetabular defects and to validate the SPECT/CT method which gives both anatomical and functional data for this purpose.

METHODS

We retrospectively reviewed 9 patients (6 female, 3 male; mean age 63.6 years). Preoperative and postoperative leg lengths, existence of the Trendelenburg sign, range of motion of the hip, visual analogue score (VAS), Harris Hip Score (HHS) and any complication were assesed at each follow-up. Radiographically, position of the cup, signs of loosening or migration, and union of the graft were all determined. At the latest follow-up, patients were evaluated with hybrid SPECT/CT.

RESULTS

The average duration of follow-up was 38.1 months (24-50 months). The overall mean HHS and VAS scores were significantly improved (p<0.05). When hybrid SPECT/CT results were evaluated, the vascular phase of scintigraphy showed hyperaemia of the graft and the bone phase of scintigraphy showed normal or increased radiotracer uptake in the graft site in 7 patients. SPECT/CT images were used to determine the exact localisation of osteoblastic activity. 1 patient with minor resorption of the graft without clinical symptoms revealed mild osteoblastic activity. The patient who had no activity in the graft site was rerevised because of infection.

CONCLUSIONS

Institutional bank allografts are still excellent options for treating large acetabular defects in revision total hip arthroplasty where trabecular metals are not available or in common use. The Hybrid SPECT/CT method is a reliable, noninvasive method for evaluating both the integrity and viability of a bulk graft in 3-D.

[Treatment of acetabular bone defects in revision hip arthroplasty using the Revisio-System]

BACKGROUND

Many different systems for the management of primary and secondary acetabular defects are available, each with its inherent advantages and disadvantages. The Revisio-System is a press-fit oval mono-block implant that makes a defect-oriented reconstruction and restoration of the center of rotation possible.

MATERIAL AND METHODS

In this study, we retrospectively reviewed the outcome of 92 consecutive patients treated with this oval press-fit cup due to periacetabular bone loss. The average follow-up was 58.2 months. Defects were classified according to D'Antonio. There were 39 type II, 38 Type III, and 15 type IV defects. After an average of 4.9 years, the implant survival rate was 94.6% with cup revision as the end point and 89.1% with revision for any reason as the end point. The Harris Hip Score increased from 41.1 preoperatively to 62.3 postoperatively. The mean level of pain measured with the Visual Analogue Scale (VSA) was reduced from 6.9 preoperatively to 3.8 postoperatively.

RESULTS

The Revisio-System represents a promising toolbox for defect-orientated reconstruction of acetabular bone loss in revision hip arthroplasty. Our results demonstrate that the implantation of the Revisio-System can result in a good mid-term clinical outcome.

Comparative survival analysis of porous tantalum and porous titanium acetabular components in total hip arthroplasty

BACKGROUND

Porous tantalum acetabular components (PoTa) are well-studied, but less is known about widely used porous titanium (PoTi) acetabular components. We performed a comparative survival analysis between PoTi and PoTa acetabular components.

METHODS

Primary or revision THA performed using PoTi (n = 2,976) or PoTa (n = 184) acetabular components with minimum 2-year follow-up (PoTi n = 1,539; PoTa n = 157) were analysed. Univariate and multivariate logistic regression were performed to test the effect of porous metal acetabular component type on revision surgery for aseptic cup loosening. Multivariate model was adjusted for acetabular defect severity according to the Paprosky Classification.

RESULTS

Only PoTi components used in revision THA failed. Survival of the PoTi acetabular component was 98.6% when used in revision THA at mean 48.3-month follow-up. After adjusting for severity of acetabular defect, there was no difference in survival between PoTi and PoTa acetabular components when used in primary or revision THA.

CONCLUSIONS

After adjusting for acetabular defect severity, both PoTa and PoTi acetabular components had excellent survival at mean 44.4-month (range 4.3-91.5 months) follow-up when used in primary and revision THA.

The Evolution of the Cup-Cage Technique for Major Acetabular Defects: Full and Half Cup-Cage Reconstruction

BACKGROUND

Complex acetabular reconstruction for major bone loss can require advanced methods such as the use of a cup-cage construct. The purpose of this study was to review outcomes after the initial development of the cup-cage technique and the subsequent evolution to the use of a half cup-cage construct.

METHODS

We performed a retrospective, single-center review of 57 patients treated with cup-cage reconstruction for major acetabular bone loss. All patients had major acetabular defects graded as Paprosky Type 2B through 3B, with 34 (60%) having an associated pelvic discontinuity. Thirty patients received a full cup-cage construct and 27, a half cup-cage construct. The mean follow-up was 5 years.

RESULTS

Both the full and half cup-cage cohorts demonstrated significantly improved Harris hip score (HHS) values, from 36 to 72 at a minimum of 2 years of follow-up (p < 0.05). Early construct migration occurred in 4 patients, with stabilization prior to 2-year follow-up in all but 1 patient. Incomplete, zone-3, nonprogressive acetabular radiolucencies were observed in 2 (7%) of the full cup-cage constructs and 6 (22%) of the half cup-cage constructs. One patient with a full cup-cage construct underwent re-revision of the acetabular component for progressive migration and aseptic loosening. Short-term survivorship free from re-revision for any cause or reoperation was 89% (83% and 96% for full and half cup-cage cohorts, respectively).

CONCLUSIONS

Both full and half cup-cage constructs demonstrated successful clinical outcomes and survivorship in the treatment of major acetabular defects and pelvic discontinuity. Each method is utilized on the basis of individual intraoperative findings, including the extent and pattern of bone loss, the quality and location of host bone remaining after preparation, and the presence of pelvic discontinuity. Longer-term follow-up is required to understand the durability of these constructs in treating major acetabular defects and pelvic discontinuity.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Promising early results for trabecular metal acetabular components used at revision total hip arthroplasty

Aims

The aim of this study was to compare the incidence of aseptic loosening after the use of a cemented acetabular component and a Trabecular Metal (TM) acetabular component (Zimmer Inc., Warsaw, Indiana) at acetabular revision with bone impaction grafting.

Patients and Methods

A total of 42 patients were included in the study. Patients were randomised to receive an all- polyethylene cemented acetabular component (n = 19) or a TM component (n = 23). Radiostereometric analysis and conventional radiographic examinations were performed regularly up to two years post-operatively or until further revision.

Results

The proximal migration was significantly higher in the cemented group. At two years, the median proximal migration was 1.45 mm and 0.25 mm in the cemented and TM groups, respectively (p = 0.02). One cemented component was revised due to dislocation. There were no revisions in the TM group.

Conclusion

Lower proximal migration in the TM group suggests that this design might be associated with a lower risk of aseptic loosening in the long term compared with an all polyethylene cemented component. Longer follow-up is required to confirm the clinical advantages of using this component at acetabular revision. Cite this article: Bone Joint J 2017;99-B:880–6.

Survivorship Analysis of Eighty Revised Hip Arthroplasties With the Impaction Grafting Technique Using Whole Femoral Head Allografts With the Articular Cartilage

BACKGROUND

Acetabular impaction bone grafting aims to restore anatomy in hip revision surgery. This is an effective but expensive and time-consuming technique. Usually, the articular cartilage is removed from the femoral head allograft. We aimed to reproduce the same results retaining the cartilage of the allograft.

METHODS

Eighty acetabular revisions using impacted morselized bone graft retaining the articular cartilage and a cemented cup were studied retrospectively. Six were lost during follow-up. The mean follow-up was 6.5 years (range 1-13). Clinical and radiological assessment was made using the Oxford Hip Score, Hodgkinson's criteria for socket loosening, and the Gie classification for evaluation of allograft incorporation.

RESULTS

Sixty-three sockets (85.1%) were considered radiologically stable (type 0, 1, and 2 demarcations), 8 (10.8%) were radiologically loose (type 3), and 3 (4.1%) presented with migration. Fifty-one (68.9%) cases showed good trabecular remodeling (grade 3), 20 (27%) showed trabecular incorporation (grade 2), and 3 (4.1%) showed poor allograft incorporation. Mean preoperative hip score was 43 and postoperative score was 28. Six (8.1%) cases presented heterotopic ossification around the revised implants, 2 patients (2.7%) had periprosthetic fractures, and 4 (5.4%) had dislocations. The Kaplan-Meier survivorship at a mean of 6.5 years with revision of the cup for any reason was 95.9% (95% confidence interval 5.6-7.5).

CONCLUSION

The mid-term results of our technique are promising. Particularly when the supply of fresh-frozen allografts and surgical time is limited, using whole femoral head with articular cartilage is both safe and effective.

Bone grafts, bone graft extenders, substitutes and enhancers for acetabular reconstruction in revision total hip arthroplasty

Acetabular bone loss is a relevant concern for surgeons dealing with a failed total hip arthroplasty.

Since the femoral head is no longer available, allografts represent the first choice for most reconstructive solutions, either as a structural buttress or impacted bone chips.

Even though fresh-frozen bone is firmly recommended for structural grafts, freeze-dried and/or irradiated bone may be used alternatively for impaction grafting. Indeed, there are some papers on freeze-dried or irradiated bone impaction grafting, but their number is limited, as is the number of cases.

Xenografts do not represent a viable option based on the poor available evidence but bioactive bioceramics such as hydroxyapatite and biphasic calcium phosphates are suitable bone graft extenders or even substitutes for acetabular impaction grafting.

Bone-marrow-derived mesenchymal stem cells and demineralised bone matrix seem to act as reliable bone graft enhancers, i.e. adjuvant therapies able to improve the biological performance of standard bone grafts or substitutes. Among these therapies, platelet-rich plasma and bone morphogenetic proteins need to be investigated further before any recommendations can be made.

Cite this article: EFORT Open Rev 2016;1:431-439. DOI:10.1302/2058-5241.160025

Are porous tantalum cups superior to conventional reinforcement rings?

Background and purpose - Porous tantalum cups have been introduced as an alternative to various reinforcement rings in revision hip surgery. We hypothesized that porous tantalum cups would be superior to Müller acetabular roof reinforcement rings (MARRs) in revision hip surgery with re-revision for aseptic loosening as the primary outcome measure. Patients and methods - 207 hips operated with either a porous tantalum cup (TM cup, n = 111) or a MARR (n = 96) at index procedure were identified in our local arthroplasty register. Acetabular defects were classified according to Paprosky. There were 96 men and 111 women with a median age of 71 (35-95) years, presenting acetabular defect size type I in 39 cases, IIA in 22, IIB in 27, IIC in 43, IIIA in 32, and IIIB in 37 cases. Analysis of medical records identified all patients with subsequent re-revision and reasons for re-revisions. Kaplan-Meier survival functions were used to estimate implant survival. Results - With re-revision for aseptic loosening as the endpoint, the 6-year unadjusted cumulative survival was 97% (95% CI: 94-100) for TM cups and 96% (CI: 92-100) for MARR (p = 0.6). Using re-revision for any reason as the endpoint, 6-year survival was 87% (CI: 81-94) for TM cups and 95% (CI: 90-99) for MARR (p = 0.06). The main reason for re-revision in the TM group was dislocation (n = 10), followed by loosening (n = 3), whereas the main reason for re-revision in the MARR group was aseptic loosening (n = 8). Duration of the index procedure and perioperative blood loss were lower in the TM group. Interpretation - Both TM and MARR lead to good 6-year results in acetabular revision surgery. The methods differ in their respective failure mechanisms. We conclude that TM cups are a valuable treatment option in acetabular revision surgery, but the reasons underlying dislocations after the use of TM cups must be analyzed further.

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.

Outcome of Revision Total Hip Arthroplasty in Management of Failed Metal-on-Metal Hip Arthroplasty

BACKGROUND

This is a retrospective review of the functional outcomes and complications of revision total hip arthroplasty (THA) of failed metal-on-metal (MoM) hip arthroplasty.

METHODS

A total of 20 revision THAs were performed in 19 patients. Of them, 2 cases were failed hip resurfacing, and 18 cases were failed (MoM) THA. The mean age at revision (THA) was 59.35 years (standard deviation [SD] 9.83).

RESULTS

The mean follow-up was 45 months (SD 13.98). The indications of revision were aseptic loosening of acetabular component without adverse local tissue reaction (ALTR; 10 hips), aseptic loosening of the acetabular and femoral components without ALTR (1 hip), painful hip associated with ALTR (6 hips), iliopsoas impingement associated with a large-diameter femoral head or malpositioned acetabular component (3 hips). The acetabular components were revised in 18 hips using Trabecular Metal Modular cups. The femoral components were revised in 3 hips. A constrained acetabular liner was used in 5 hips. The Harris hip score significantly improved from 48.4 (SD 12.98) to 83.25 (SD 10.08). There were 2 complications (1 foot drop and 1 superficial infection) and 1 failure (recurrent dislocation) that required revision to a constrained liner.

CONCLUSION

Early results of revision THA of failed MoM hip arthroplasty showed improvement in pain and functional outcome. No case of failed bone ingrowth was noted with the use of Trabecular Metal Modular cups. Extensive soft tissue and abductor muscles dysfunctions were common. A constrained acetabular component with repair of the hip abductors might be beneficial.

Use of porous tantalum components in Paprosky two and three acetabular revision. A minimum five-year follow-up of fifty one hips

INTRODUCTION

Recent studies have reported short-term favourable results of tantalum-made components in acetabular revisions with bone loss. However, there is a lack of information regarding the mid to long-term results of such components.

OBJECTIVES

The objective of this study was to analyse the outcome and survivorship of acetabular revision hip arthroplasty using tantalum components for loosening associated with bone loss at a minimum of five-year follow-up.

METHODS

We retrospectively reviewed 51 consecutive patients (51 hips) who had an acetabular revision using porous tantalum components at a minimum follow-up of five years. The mean age was 64 years (range, 31-87). There were 27 males and 24 females, 47 right hips and four left hips. Twenty-five (49 %) included a femoral revision. According to Paprosky's classification 18 hips were classified type 2A, 11 type 2B, ten type 2C, seven type 3A and five type 3B. No bone grafting was performed. Sixteen hips (31.3 %) required the use of additional tantalum-made augments stabilized by screws and cement at the cup-augment interface.

RESULTS

At a mean followup of 6.8 years (range, 5.1-10 years), the Harris hip score improved from 44 pre- operatively (range, 23-72) to 84 post-operatively (range, 33-98). The mean post-operative hip centre position in relation to the teardrop was 29 mm (range, 20-43 mm) horizontally and 21 mm (range, 8-36 mm) vertically. The mean acetabular inclination was 42° (range, 17-60°). Six hips (11.7 %) required a re-operation without component revision (two for chronic instability, one ossification removal, one haematoma, one deep infection and one periprosthetic femoral fracture). One patient required a cup re-revision for septic loosening. No aseptic loosening occurred. At last followup the radiological analysis showed one evolutive osteolysis and one screw breakage. The global survivorship was 92.3 % at 64 months. If only aseptic loosening was defined as the end-point the survivorship was 100 % at 64 months.

CONCLUSIONS

When facing an acetabular revision with severe bone loss, tantalum-made components can provide a stable fixation. This study at a minimum five-year follow-up compares favourably with other reconstruction techniques, but longer follow-up is still required.

Porous tantalum uncemented acetabular components in revision total hip arthroplasty

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.

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.

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.

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.

The jumbo acetabular component for acetabular revision

The ‘jumbo’ acetabular component is now commonly used in acetabular revision surgery where there is extensive bone loss. It offers high surface contact, permits weight bearing over a large area of the pelvis, the need for bone grafting is reduced and it is usually possible to restore centre of rotation of the hip. Disadvantages of its use include a technique in which bone structure may not be restored, a risk of excessive posterior bone loss during reaming, an obligation to employ screw fixation, limited bone ingrowth with late failure and high hip centre, leading to increased risk of dislocation. Contraindications include unaddressed pelvic dissociation, inability to implant the component with a rim fit, and an inability to achieve screw fixation. Use in acetabulae with < 50% bone stock has also been questioned. Published results have been encouraging in the first decade, with late failures predominantly because of polyethylene wear and aseptic loosening. Dislocation is the most common complication of jumbo acetabular revisions, with an incidence of approximately 10%, and often mandates revision. Based on published results, a hemispherical component with an enhanced porous coating, highly cross-linked polyethylene, and a large femoral head appears to represent the optimum tribology for jumbo acetabular revisions.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):64–7.

Clinical evaluation and surgical options in acetabular reconstruction: A literature review

The purpose of this paper is to review the clinical indications for acetabular reconstruction in patients with underlying peri-prosthetic segmental and cavitary defects, evaluate steps in pre-operative planning, and present the American Academy of Orthopaedic Surgeons (AAOS) and Paprosky classification systems to categorize acetabular defects. We also present a review of the current surgical techniques to reconstruct the acetabular socket which includes a cementless acetabular component with morselized bone, structural allograft, jumbo and oblong cups, reinforcement rings, bone cages, custom triflange acetabular constructs, and trabecular metal components.