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

Pelvic Reconstruction for Complex Bone Defects in Revision Total Hip Arthroplasty

Pelvic bone loss in the setting of total hip arthroplasty (THA) creates a challenge for reconstructing the acetabulum during revision THA. The complexity of managing acetabular bone loss lies in its highly variable presentation, ranging from minor osteolytic defects to extensive segmental and cavitary deficiencies. This article will highlight treatment options for complex pelvic defects (Paprosky 3A/3B) and frequently associated pathology, such as instability and infection.

Custom Acetabular Components in Revision Total Hip Arthroplasty: A Systematic Review

INTRODUCTION

Custom acetabular components (CACs) have demonstrated promising results in revision total hip arthroplasties (THAs) with substantial acetabular bone loss. However, previous systematic reviews are limited by short follow-up. The purpose of this systematic review was to report midterm outcomes of CACs in revision THAs.

METHODS

The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were followed. We searched MEDLINE, EMBASE, Cochrane Databases, and Scopus databases for English publications with a minimum 2-year follow-up. There were 14 studies that met the inclusion criteria, with 592 CACs available for re-revision and implant removal analysis and 603 available for reoperation analysis. The mean age was 63 years, the mean BMI was 29, and 68% were women. The mean follow-up was seven years.

RESULTS

The CAC re-revision rate was 19 per 1,000 person-years of follow-up (n = 84), the all-cause re-revision rate was 21 per 1,000 person-years (n = 93), and the CAC removal rate was eight per 1,000 person-years (n = 36). The most common indications for CAC re-revision included dislocation (n = 31), periprosthetic joint infection (PJI, n = 30), and CAC aseptic loosening (n = 12). The indications for CAC removal included PJI (n = 22), aseptic loosening (n = 12), and dislocation (n = 2). In addition to the 93 re-revisions, there were 37 reoperations (28 per 1,000 person-years). The mean Harris Hip Score improved from 38 to 75 at final follow-up.

CONCLUSION

In this systematic review including over 600 CACs, the re-revision rate was 19 per 1,000 person-years, but 94% of CACs were retained at a mean of seven years of follow-up. Considering the complexity of these cases, CACs have acceptable survivorship. Dislocation and PJI contributed to the high re-revision rate, while PJI and aseptic loosening were the most common reasons for implant removal.

LEVEL OF EVIDENCE

Level IV, Systematic Review of Case Series.

Re-revision Following Failed Revision Total Hip Arthroplasty in a Case of Neglected Inferior Dislocation of the Hip: An Interesting Case Report

Introduction

Revision arthroplasty is challenging, especially in severe acetabular bone loss cases. Metal augments have emerged as a viable option for managing such complex defects.

Case Report

We report a case of a 59-year-old male who underwent re-revision arthroplasty using a metal augment for severe acetabular bone loss, restoring limb length and anatomical hip center following a failed revision total hip arthroplasty in a case of neglected inferior hip dislocation. The patient presented with significant pain, instability, and limited mobility. Postoperative outcomes showed considerable improvement, with a Harris Hip Score increasing from 37 to 82 at the 12-month follow-up.

Conclusion

In conclusion, this case report demonstrates the effectiveness of metal augments in revision arthroplasty for managing significant bone loss. Careful patient selection and expert surgical techniques can provide a reliable solution for ensuring stable fixation and improving clinical outcomes in complex revision surgeries.

Severe acetabular bone loss management: is there still a role for titanium cages and cemented cups?

INTRODUCTION

Bone loss represents a formidable challenge in hip revision surgery. Recent advances in revision implants and the use of new materials have diminished the need for cup-cages in addressing severe acetabular bone loss, which, however, may still be indicated in certain situations. The objectives of this study are to assess survival, functional outcomes, and reasons for the failure of managing severe acetabular bone loss with titanium cages and cemented cup.

METHODS

57 patients treated with an acetabular cage and cemented cup for acetabular revision between January 2014 and July 2018 were retrospectively evaluated. Inclusion criteria comprised cup loosening with bone loss greater than IIB according to Paprosky classification, and a follow-up of at least 60 months.

RESULTS

The average age at the time of surgery was 74.8 years (SD 10.7). The acetabular bone defect according to the Paprosky classification was: type II C in 10 patients (21.7%), type III A in 21 patients (45.7%) and type III B in 15 patients (32.6%). Pelvic discontinuity was present in 35 cases (76.1%). The average follow-up during the final assessment was 78.3 months (SD 14.9). The reoperation rate was 13% (6 patients) and the complications rate was 17.4%. The survivorship of the implant was 87% at final follow-up.At the final follow-up average HHS was 89.4 ± 13.4, average WOMAC 15.7 ± 17.2, average HOOS 81.3 ± 19 and average FJS-12 83.7 ± 17.2. At the final follow-up, 32 patients (80%) showed excellent or good outcomes (HHS >80).

CONCLUSIONS

In the presence of severe bone defects, acetabular reconstruction using titanium acetabular cages and cemented UHMWPE cups remains a valid treatment option. Specifically, this acetabular reconstruction system should be favoured for elderly or low-demand patients, with the possibility of using it safely even in patients with pelvic discontinuity.

Cup-Cage Reconstruction for Pelvic Discontinuity: Encouraging Long-Term Survival

BACKGROUND

Pelvic discontinuity (PD) poses a difficult challenge in revision total hip arthroplasty. There is a paucity of evidence assessing 5- to 10-year outcomes of cup cages for PD. This study aimed to review the survivorship and outcomes of cup-cage constructs for PD.

METHODS

Cases without PD or with < 2-year follow-up were excluded. There were 48 cup-cage revisions identified with a mean follow-up of 7.2 years (range, 2 to 20). The mean age was 77 years, and 71% were women. Kaplan-Meier analysis was used to determine survival with all-cause and aseptic loosening rerevision as endpoints. Secondary outcomes included radiological failures and patient-reported outcomes.

RESULTS

All-cause rerevision survival was 80% (95% confidence interval [CI]: 0.70 to 0.93) at 5 years and 68% (95% CI: 0.54 to 0.85) at 10 years. Rerevision survival for aseptic loosening of the cup-cage construct was 95% (95% CI: 0.89 to 1.00) at 5 years and 85% (95% CI: 0.74 to 0.98) at 10 years. There were 13 (27%) patients who underwent rerevision at a mean of 45 months post revision total hip arthroplasty (range, 1 to 112). Aseptic loosening prompted rerevision in five of 48 (10%) cases at a mean of 68 months (range, 29 to 98). Of these, three required cup revisions for loosening and two required isolated cage/liner revisions with well-fixed cups. There were three patients who had resection arthroplasty for chronic infection. There were three patients revised for instability with liner exchange or femoral revision only, as the cup-cage constructs had not failed. Patient-reported pain (mean Western Ontario and McMaster Universities Arthritis Index: 83.5) and function (mean Western Ontario and McMaster Universities Arthritis Index function: 75.4; Oxford Hip Score: 71.2) were acceptable.

CONCLUSIONS

Cup-cage reconstruction is a good solution for PD with encouraging five-year to 10-year results and acceptable survivorship and patient-reported outcome measures.

What Are the Functional, Radiographic, and Survivorship Outcomes of a Modified Cup-cage Technique for Pelvic Discontinuity?

BACKGROUND

Pelvic discontinuity (PD) presents a complex challenge in revision hip arthroplasty. The traditional cup-cage construct, which involves a screw-secured porous metal cup and an overlying antiprotrusio cage, has shown promising mid- to long-term results. However, there is limited information on the outcomes of modifications to the original technique. Our study aims to evaluate a modified technique in which the cup position is determined by the placement of the overlying cage, allowing for adjustments to achieve optimal orientation.

QUESTIONS/PURPOSES

Among patients treated for PD with a cup-cage construct in which the cup position was dictated by the position of the cage: (1) What are Harris hip scores achieved at a minimum of 2 years of follow-up? (2) What is the Kaplan-Meier survivorship free from aseptic loosening or component migration? (3) What is the Kaplan-Meier survivorship free from revision for any reason? (4) What surgical complications are associated with the procedure?

METHODS

Between October 2013 and January 2022, we performed 805 acetabular revisions. Among these, 33 patients with PD confirmed intraoperatively were considered potentially eligible for a cup-cage construct; no other method of surgical management was used. We performed 64% (21 of 33) of these procedures from October 2013 to January 2018, with 6% (2 of 33) of patients lost to follow-up before the minimum study follow-up of 2 years; these 19 patients were monitored over a period ranging from 70 to 115 months. A further 12 patients underwent this procedure from January 2018 to January 2022, with one lost to follow-up before the minimum study follow-up of 2 years; the other patients met the minimum 2-year follow-up requirement. The remaining 30 patients with data analyzed here (10 men, 20 women) had a mean ± SD age of 61 ± 12 years and a median BMI of 29 kg/m 2 (range 20 to 33 kg/m 2 ) at the time of revision surgery. Twenty-one patients underwent revision due to aseptic loosening, and nine due to periprosthetic joint infection (PJI). The causes of PD in our patients were as follows: cup aseptic loosening without significant osteolysis in 20% (6 of 30), where the loose cup caused erosion of the host bone, leading to PD; PJI in 30% (9 of 30); intraoperative iatrogenic PD in 3% (1 of 30); and osteolysis in 47% (14 of 30), which also resulted in aseptic loosening. The median follow-up time was 79 months (range 25 to 115 months). The Harris hip score was used to evaluate clinical outcomes, with preoperative values compared with the most recent follow-up. Radiographs were reviewed by two experienced surgeons at each follow-up visit to assess component loosening (defined as migration > 5 mm or the presence of circumferential radiolucent lines) or clear migration. PD was considered healed if bridging callus or trabecular bone was visible across the site of the discontinuity. Complications were assessed through a comprehensive review of electronic medical records. Kaplan-Meier analysis was used to estimate implant survivorship and radiographic loosening, with aseptic loosening or component migration as the endpoint, as well as survivorship free from any reoperation.

RESULTS

The Harris hip score improved from a median of 39 (range 30 to 66) preoperatively to a median of 76 (range 30 to 90) postoperatively (median difference 33 [range 2 to 48]; p < 0.01). Within the limitations of two-dimensional (2D) radiographic imaging, successful bone graft integration and the healing of PD were noted in 83% (25 of 30) of patients. Kaplan-Meier survivorship free from radiographic signs of aseptic loosening or component migration was 100% (95% CI 100% to 100%) at 115 months. When any revision related to the acetabular component was considered the endpoint, survivorship free from acetabular component revision at 115 months after revision surgery was 100% (95% CI 100% to 100%). When the need for any reoperation was considered the endpoint, survivorship free from needing reoperation at 115 months after revision surgery was 85% for all patients (95% CI 73% to 100%). When including only patients with a follow-up time of > 4 years (20 of 30), survivorship free from needing reoperation at 115 months after revision surgery was 90% (95% CI 78% to 100%). Postoperative complications during the follow-up period included one early dislocation on the fifth day after surgery, treated with closed reduction and 6 weeks of abduction bracing. One femoral stem loosening occurred at 56 months postoperatively, although the acetabular component remained securely fixed; this patient declined revision surgery. One patient experienced a dislocation 5 months after surgery but refused treatment and opted for prolonged bed rest. Additionally, one patient underwent a debridement, antibiotics, and implant retention procedure 1 week after the revision surgery and subsequently showed no signs of infection at the latest follow-up, 38 months postoperatively.

CONCLUSION

Our study highlights the effectiveness of a modified cup-cage technique in complex hip revisions, showing promising results in terms of construct survivorship and low complication rates. Surgeons could consider delaying screw fixation until after positioning the cage within the porous cup to allow for optimal adjustment and using metal augments for severe bone defects to achieve better alignment. Surgeon experience with the cup-cage technique is crucial for achieving optimal outcomes. Future studies should focus on long-term follow-up visits to assess the durability and effectiveness of these modifications and explore the comparative effectiveness versus other methods, such as custom triflange components and jumbo cups with distraction.

LEVEL OF EVIDENCE

Level III, therapeutic study.

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.

Highly Porous Acetabular Cup and Augment Constructs in Complex Revision Total Hip Arthroplasty: What Predicts 10-Year Implant Survivorship?

BACKGROUND

Porous tantalum acetabular cup and augment constructs have demonstrated favorable outcomes up to 5 years postsurgery despite severe bone loss during revision total hip arthroplasty (THA). Prior literature lacks long-term studies with substantial case numbers. This study aims to assess long-term clinical and radiographic outcomes 10 years postsurgery in patients undergoing revision THA with porous tantalum acetabular cup-augment constructs and determine factors associated with long-term survivorship.

METHODS

Between 2000 and 2012, 157 revision THAs were performed in cases with major acetabular defects (mainly Paprosky type IIIA and IIIB) utilizing porous tantalum cup-augment constructs. Pelvic discontinuity was noted intraoperatively in 17 hips (11%). Postoperative radiographs were evaluated at regular intervals for implant stability and radiolucent lines. There were 49 patients who had complete radiographic follow-up at 10 years or longer postsurgery.

RESULTS

The 10-year survivorship free of revision of the cup-augment construct for aseptic loosening was 93%, free of any acetabular construct revision was 91%, free of any hip rerevision was 77%, and free of any reoperation was 75%. Pelvic discontinuity was associated with increased risk of reoperation (hazard ratio [HR] = 2.8), any hip rerevision (HR = 3.2), any cup-augment construct revision (HR = 11.8), and aseptic construct revision (HR = 10.0). Of unrevised cases with radiographs at 10 years, 4 hips showed radiographic loosening. Mean Harris hip scores improved from 47 preoperatively to 79 at 10 years.

CONCLUSIONS

Porous tantalum acetabular cup-augment constructs used in revision THA with severe acetabular bone loss provide excellent implant survivorship at 10 years when the acetabulum is intact. Due to lower survivorship of cup-augment constructs in cases of pelvic discontinuity, additional construct fixation or stabilization methods are recommended, when a discontinuity is present.

LEVEL OF EVIDENCE

IV.

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.

Can a reconstruction algorithm in major acetabular bone loss be successful in revision hip arthroplasty?

Aims

The aims of this study were to determine the success of a reconstruction algorithm used in major acetabular bone loss, and to further define the indications for custom-made implants in major acetabular bone loss.

Methods

We reviewed a consecutive series of Paprosky type III acetabular defects treated according to a reconstruction algorithm. IIIA defects were planned to use a superior augment and hemispherical acetabular component. IIIB defects were planned to receive either a hemispherical acetabular component plus augments, a cup-cage reconstruction, or a custom-made implant. We used national digital health records and registry reports to identify any reoperation or re-revision procedure and Oxford Hip Score (OHS) for patient-reported outcomes. Implant survival was determined via Kaplan-Meier analysis.

Results

A total of 105 procedures were carried out in 100 patients (five bilateral) with a mean age of 73 years (42 to 94). In the IIIA defects treated, 72.0% (36 of 50) required a porous metal augment; the remaining 14 patients were treated with a hemispherical acetabular component alone. In the IIIB defects, 63.6% (35 of 55) underwent reconstruction as planned with 20 patients who actually required a hemispherical acetabular component alone. At mean follow-up of 7.6 years, survival was 94.3% (95% confidence interval 97.4 to 88.1) for all-cause revision and the overall dislocation rate was 3.8% (4 of 105). There was no difference observed in survival between type IIIA and type IIIB defects and whether a hemispherical implant alone was used for the reconstruction or not. The mean gain in OHS was 16 points. Custom-made implants were only used in six cases, in patients with either a mega-defect in which the anteroposterior diameter > 80 mm, complex pelvic discontinuity, and massive bone loss in a small pelvis.

Conclusion

Our findings suggest that a reconstruction algorithm can provide a successful approach to reconstruction in major acetabular bone loss. The use of custom implants has been defined in this series and accounts for < 5% of cases.

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.

Reconstruction of Paprosky IIIB acetabular defects with porous tantalum shells and augments using the footing technique

Aims

The use of a porous metal shell supported by two augments with the 'footing' technique is one solution to manage Paprosky IIIB acetabular defects in revision total hip arthroplasty. The aim of this study was to assess the medium-term implant survival and radiological and clinical outcomes of this technique.

Methods

We undertook a retrospective, two-centre series of 39 hips in 39 patients (15 male, 24 female) treated with the 'footing' technique for Paprosky IIIB acetabular defects between 2007 and 2020. The median age at the time of surgery was 64.4 years (interquartile range (IQR) 54.4 to 71.0). The median follow-up was 3.9 years (IQR 3.1 to 7.0).

Results

The cumulative medium-term survival of the acetabular construct was 89%. Two hips (5.1%) required further revision due to shell loosening, one hip (2.6%) due to shell dislocation, and one hip (2.6%) due to infection. The median Harris Hip Score improved significantly from 47 points (IQR 41.5 to 54.9) preoperatively to 80 points (IQR 73.5 to 88.6) at the latest follow-up (p < 0.001).

Conclusion

The reconstruction of Paprosky IIIB acetabular defects with porous tantalum shells and two augments using the 'footing' technique showed excellent medium-term results. It is a viable option for treating these challenging defects.

Bridging Massive Acetabular Defects With the Triflange Cup: 10- to 28-Year Results

BACKGROUND

Massive acetabular bone loss, encountered complex primary or revision total hip arthroplasty, remains a reconstructive challenge. The custom triflange cup reliably achieves both early fixation and longer-term stability. This study presents the 10-year minimum three-surgeon follow-up of acetabular defects managed with a custom triflange component.

METHODS

All patients who underwent a custom triflange acetabular component implantation from January 1992 to December 2009 were identified. Demographics, implant data, outcomes, and reoperations were collected and analyzed. Bone defects in all cases were Paprosky type IIIA, IIIB, or IV. A total of 233 patients (241 hips) underwent implantation of a custom triflange during the study period. There were 81 patients (83 hips) who died prior to minimum follow-up and 84 patients (88 hips) had minimum follow-up of 10 years (mean 15.2; range, 10 to 28), or failure prior to 10 years.

RESULTS

Complications requiring additional surgery occurred in 43 hips (49%). There were 10 revisions for failure (11.4%); four were due to recurrent infection, three for aseptic loosening, and one for recurrent infection with all revised to a new triflange. There was one patient who was resected to a Girdlestone for infection and one patient was revised for infection to a bipolar hemiprosthesis due to a healed discontinuity.

CONCLUSION

To our knowledge, this study represents the largest cohort and longest follow-up in the current literature and demonstrates excellent survivorship and clinical results at an average of 15 years follow-up. The component was retained in 89% of cases.

Treatment of Severe Acetabular Defects With an Antiprotrusio Cage and Trabecular Metal Augments - Clinical and Radiographic Results After a Mean Follow-Up of 6.6 Years

BACKGROUND

Large acetabular bone defects present a serious challenge in revision total hip arthroplasty. The off-label use of antiprotrusio cages in combination with tantalum augments is a promising treatment option in these difficult situations.

METHODS

Between 2008 and 2013, 100 consecutive patients underwent acetabular cup revision with a cage-augment combination in Paprosky 2 and 3 defect types (including pelvic discontinuities). There were 59 patients available for follow-up. The primary endpoint was the explantation of the cage-and-augment construct. The secondary endpoint was acetabular cup revision for any reason. Also, radiographic and functional outcomes (Western Ontario and McMaster Universities Osteoarthritis Index, Harris Hip Score) were evaluated. Implant survival rates were determined using a Kaplan-Meier analysis. The significance level was set at P < .05.

RESULTS

Explantation-free survivorship of the "Cage-and-Augment" system was 91.9% after a mean follow-up of 6.2 years (range, 0 to 12.8). All 6 explantations were due to periprosthetic joint infection (PJI). The overall revision-free implant survival rate was 85.7%, including 6 additional liner revisions due to instability. In addition, 6 early PJI occurred, which were successfully treated with debridement, irrigation, and implant retention. We did observe one patient who had radiographic loosening of the construct without necessity for treatment.

CONCLUSION

The combination of an antiprotrusio cage with tantalum augments is a promising technique in treating large acetabular defects. A major risk of PJI and instability due to large bone and soft tissue defects needs special attention.

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.

Management of Acetabular Bone Loss in Hip Revision Arthroplasty: Case Series Presentation

Considering the increase in life expectancy in the general population and the need for a more active lifestyle, total hip arthroplasty has become an absolutely necessary surgical intervention to maintain these desired results. Along with the evolution of medicine and the increase in the quality and performance of the materials used to make prostheses, the number of patients who benefit from total hip replacement is constantly increasing, and proportionally, the number of patients who will require revision arthroplasty is increasing. Before discussing the need for hip arthroplasty revision, it is necessary to carry out a rigorous clinical and imaging examination for differential diagnosis with other pathologies such as low back pain, the presence of bone or soft tissue tumors, arterial occlusions and claudication, or other systemic diseases. One of the biggest challenges for the orthopedic surgeon in planning a hip revision is the compensation of the remaining acetabular bone defect, either as a result of the osteolysis process or following the process of removing the acetabular component, which in some cases can lead to severe bone loss that is difficult to anticipate in the preoperative planning. In this paper, we will present the short-term results of the use of reinforcement cages fixed with screws and cemented retentive acetabular cups in the case of hip revisions with extensive bone loss. The discussions that derive from the presented series of cases are related to the use of reinforcement cages, which are based on the principle of primary stability obtained with the help of screw fixation but whose risk of osteolysis and implant fixation damage is greater than in the case of implants that also associate biological integration at bone level. The use of reinforcement cages together with the retentive acetabular cup in the case of elderly patients with associated comorbidities, a moderate level of physical activity, and severe muscle insufficiency at the hip level as a result of not using the affected pelvic limb is still a viable solution that allows the patient to walk immediately after the surgery, avoiding the risk of dislocation (especially in patients who use the posterolateral approach) and avoiding morbidity induced by prolonged bed rest.

Metal Augments Used in Revision Hip Arthroplasty: A Systematic Review and Single-Arm Meta-Analysis

BACKGROUND

Porous metal augments are used in complex hip arthroplasty; however, few studies have assessed their efficacy and safety. This systematic review analyzed the use of augments in revision hip arthroplasty and summarized the clinical research findings.

METHODS

We used combinations of "revision," "replacement," "arthroplasty," "augment," "acetabular," and "hip" to search PubMed, Web of Science, EMBASE, Cochrane Library databases, and clinical trial registration platform "Clinicaltrials" for relevant literature. The functional score, restoration of hip center of rotation, revision of implants, and complications were analyzed. Patients were divided into 3 subgroups according to the mean follow-up period. Overall, 19 reports involving 647 patients (655 hips) were selected. The mean age at the time of surgery was 63 years (range, 24-106) and the mean follow-up duration was 66 months (range, 11-204).

RESULTS

Harris Hip Score increased from approximately a mean of 40 points preoperatively to a mean of 84 points postoperatively. The vertical distance between hip center of rotation and teardrop was restored from a preoperative distance of 41.9 to 21.7 mm postoperatively. The overall acetabular revision rate was 4.7%, and the incidence of complications was 8.2%. There were significant differences in the reoperation, acetabular revision, and complication rates among the subgroups.

CONCLUSION

Metal augments used in revision hip arthroplasty are a safe and effective treatment option to correct acetabular defects.

RSA Measurements of Implant Instability in a Paprosky III Pelvic Defect with Discontinuity: A Case Report

CASE

We report a case of acetabular reconstruction for a large defect with pelvic discontinuity that underwent 4 revisions for dislocations over a 3-year period. This allowed assessment of implant stability both on imaging, using measurements on plain radiographs and radiostereometric analysis (RSA) against both ilium and ischium, and direct assessment during each surgery. Only implant stability measured with RSA correlated with intraoperative revision findings.

CONCLUSION

This case underlines the role of RSA in assessing early acetabular implant stability in pelvic discontinuity and the importance of assessing the stability of the implant against both ilium and ischium.

Extended Ischiopubic Fixation Using Porous Metal Augments in Cementless Acetabular Reconstruction during Revision Total Hip Arthroplasty

Objectives

The aims of this study were to introduce the definition, indication, and surgical technique of extended ischiopubic fixation (EIF) and to investigate the early clinical, radiographic results and complications of hips revised with EIF.

Methods

Patients who underwent revision THA utilizing the technique of EIF which was defined as securing the porous metal augment >5 mm deep into the ischium and/or pubic ramus to gain adequate mechanical support and fresh host bone for bony ingrowth in a single institution from February 2015 to February 2020 were retrospectively reviewed. After applying the inclusion and exclusion criteria, a total of 30 hips (28 patients) were eligible for the study and were enrolled. Four patients were lost to follow‐up postoperatively. The data of the remaining 24 patients (26 hips) were analyzed. The patients' clinical results were assessed using of the Harris Hip Score and any complications including postoperative periprosthetic joint infection, intraoperative fracture, postoperative periprosthetic fracture, dislocation, nerve palsy, hematoma or wound complication were documented. The radiographic results were assessed with the construct stability, the position of the center of rotation, and cup orientation.

Results

The median age of these 25 patients was 62.00 (interquartile: 54.25–68.25) years, with a median body mass index (BMI) of 22.60 kg/m² (interquartile: 21.49–25.12 kg/m²). A total of 12 (48%) patients were female. At a median duration of follow‐up of 49.16 months, 20 (80%) patients rated their satisfaction level as “very satisfied,” five (20%) were “satisfied.” The median HHS improved from 36.00 (interquartile range: 31.25–49.75) preoperatively to 81.00 (interquartile range: 74.75–88.25) at the most recent follow‐up (p < 0.001). No complications such as periprosthetic joint infection, intraoperative fracture, periprosthetic fracture, dislocation, nerve palsy, hematoma, or wound complication were identified. All constructs were considered to have obtained stable fixation. The median vertical and horizontal distance between the latest postoperative centers of rotation to the anatomic center of rotation improved from 13.62 and 8.68 mm preoperatively to 4.42 and 4.19 mm at final follow‐up (p < 0.001).

Conclusions

Early follow‐up of patients reconstructed with porous metal augments using the EIF technique demonstrated satisfactory clinical results with no particular complications, stable fixation, and restoration of the center of rotation.

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.

Reconstruction with a cage outlives patients with metastatic disease involving the acetabulum

AIM

The aim of this study was to determine whether patients treated with a caged reconstruction for metastatic acetabular disease would have a construct survival superior to that of their life expectancy.

PATIENTS AND METHODS

We undertook a retrospective study, in a single centre in the United Kingdom, reviewing outcomes for 19 patients (20 hips) treated with a cage reconstruction for metastatic disease of their acetabulum over 6 years. Inclusion criteria were those with an impending fracture of the acetabulum, metastatic dissociation, fracture of the acetabulum and or femur and those whose life expectancy was considered by the oncology team to be >6 months.

RESULTS

In all patients the Restoration GAP II acetabular cage (Stryker, Howmedica Osteonics Corp, NJ, USA) was used in conjunction with a cemented acetabular cup and cemented femoral stem. The mean age at the time of surgery was 68 (44-87) years with breast cancer being the most common primary malignancy (31%) followed by prostate cancer (26%).Radiological survivorship estimates were 94.1% (95% CI, 99.2-65.0) at 12 and 24 months, 70.6% (95% CI, 93.6-16.0) at 36 months and 35.3% (95% CI, 78.2-1.2) at 48 months. There were 3 radiological failures of the implant due to disease progression. Complications occurred in 3 patients with 2 developing deep infection which was treated with suppressive antibiotic therapy following aspiration of the hip. 1 patient suffered a hip dislocation following trauma which was successfully reduced closed and no further intervention was required.

CONCLUSIONS

This study represents the first published case series of the use of the GAP II cage in patients with metastatic acetabular disease. The construct generally outlives the patient and hence is suitable for the treatment of acetabular metastases.

The Diagnosis and Treatment of Acetabular Bone Loss in Revision Hip Arthroplasty: An International Consensus Symposium

Despite growing evidence supporting the evaluation, classification, and treatment of acetabular bone loss in revision hip replacement, advancements have not been systematically incorporated into a single document, and therefore, a comprehensive review of the treatment of severe acetabular bone loss is needed. The Stavros Niarchos Foundation Complex Joint Reconstruction Center at Hospital for Special Surgery held an Acetabular Bone Loss Symposium on June 21, 2019, to answer the following questions: What are the trends, emerging technologies, and areas of future research related to the evaluation and management of acetabular bone loss in revision hip replacement? What constitutes the optimal workup and management strategies for acetabular bone loss? The 36 international experts convened were divided into groups, each assigned to discuss 1 of 4 topics: (1) preoperative planning and postoperative assessment; (2) implant selection, management of osteolysis, and management of massive bone loss; (3) the treatment challenges of pelvic discontinuity, periprosthetic joint infection, instability, and poor bone biology; and (4) the principles of reconstruction and classification of acetabular bone loss. Each group came to consensus, when possible, based on an extensive literature review. This document provides an overview of these 4 areas, the consensus each group arrived at, and directions for future research.

Reconstruction of severe acetabular bone defects with porous metal augment in total hip arthroplasty: A finite element analysis study

This study aims to evaluate the reconstructive stability for Paprosky III acetabular defects after total hip arthroplasty using three different reconstruction strategies with trabecular metal (TM) augments. The acetabular bone defects examined were located in the ilium, the sciatic ramus and the pubic ramus. Different scenarios of acetabular reconstructions were simulated, including the non-reconstruction model (NRM), the complete reconstruction model (CRM), the two-point reconstruction model (TRM) and the superior edge reconstruction model (SRM). A primary hip replacement model (HRM) was also investigated to compare the initial stability with different reconstruction models. The gait cycle was incorporated in the model to investigate the dynamic variation within the contact mechanics parameters. By comparing the SRM and the TRM, the acetabular cup translation was more pronounced when the superior defect on the acetabulum remained unfixed. Comparison of the acetabular cup displacement and the interface micromotion of both HRM and CRM demonstrated that the prosthetic implant provided good support for the reconstructed acetabulum. With the use of a press-fit cup, the cup displacement was reduced remarkably, while its Von-Mises stress increased significantly. The results show that the CRM was the best reconstruction option. In terms of acetabular defects, future improvements should focus on the reconstructive stability in stress concentration areas, to ensure no significant stress-shielding or other factors contributing to loosening of the prosthesis.

Modular revision strategy with bispherical augments in severe acetabular deficiency reconstruction

PURPOSE

Reconstruction of severe acetabular deficiency is extremely challenging in total hip arthroplasty (THA) revisions. Novel bispherical augments were designed to fill acetabular bone loss and facilitate restoration of hip center of rotation (HCOR). Current study aims to compare the outcomes of bispherical augments and tantalum augments.

METHODS

Between July 2017 and December 2018, bispherical augments (BA group) were implanted in 25 patients (25 hips) and 22 patients (22 hips) underwent porous tantalum augments (TA group) reconstruction in revision THA. Clinical and radiographic results were evaluated for 25 hips in BA group and 20 hips in TA group at the final follow-up. The mean duration of follow-up was 2.9 years (range, 2.2 ~ 3.7) in BA group and 2.9 years (range, 2.3 ~ 3.8) in TA group.

RESULTS

Harris hip scores, HCOR, and leg length discrepancy (LLD) correction did not differ between the treatment groups. The bispherical augments were located more closer to the medial-superior part (zone II) of acetabular shell while the majority of tantalum augments were located at the lateral-superior part (zone I) (P = 0.010). More screws were used in the BA group for augment fixation (mean 2.1 vs. 1.3) (P = 0.000). There was no evidence of loosening or migration in all hips. Only one dislocation occurred in BA group and treated with closed reduction, no recurrence of instability up to the final follow-up.

CONCLUSION

The clinical and radiological outcomes of bispherical augments were comparable with tantalum augments; this technique was a reliable alternative method in severe acetabular deficiency reconstruction.

Multicup reconstruction technique for the management of severe protrusio acetabular defects

Background

In revision hip arthroplasty, managing the large protrusio acetabular defects remains a challenge. The report described a novel technique which employs a trabecular metal revision shell as a super-augment to buttress the superior medial structure.

Methods

Between January 2015 and December 2018, the multicup reconstruction was performed in 21 patients with severe protrusio acetabular defects. The revision shell, plus two similar porous acetabular components was implanted into the initial shell to create a “multicup” construct. The functional outcomes were evaluated in terms of the Harris Hip Score. Acetabular loosening, restoration of hip center of rotation, and bone ingrowth etc., were radiographically assessed. The survival rate of the implants was also evaluated.

Results

A followup lasting a mean time of 31 months (range, 18–57 months) revealed that the average Harris Hip Score improved from preoperative 37.0 ± 7.1 to postoperative 76.4 ± 9.0. There were no revisions due to acetabular loosening. The horizontal offset increased by an average of 14 mm, and the vertical offset decreased by an average of 18 mm. Eighteen of the 21 patients (86 %) met at least 3 of 5 criteria associated with bone ingrowth. The survivorship free from re-revision for acetabular loosening after 2 years was 100 %.

Conclusions

The multicup reconstruction technique was a simplified re-revision procedure for managing the severe protrusio acetabular defects and could achieve a high survival rate.

Level of evidence

Therapeutic study, Level IVa.

Excellent Midterm Results of Triflange Patient Matched Implants for Extensive Acetabular Bone Defect

Purpose

Reconstruction of extensive acetabular bone defects is one of the most challenging problems encountered by arthroplasty surgeons. Triflange patient matched implants (PMI) offer the potential advantages of immediate, rigid fixation with a superior individualized fit. The purpose of this study was to evaluate the clinical and radiographic midterm results of PMI in extensive acetabular defect reconstruction.

Materials and Methods

The current prospectively designed retrospective review examined 13 consecutive patients (5 males and 8 females) with a mean age of 69 years undergoing revision hip arthroplasty with Paprosky type 3B acetabular defects reconstructed using PMI between October 2011 and December 2016. A successful result was defined as a postoperative increase in Harris hip score (HHS) of >20 points with a radiographically stable implant (assessed with hip X-rays) and no need for additional acetabular reconstruction.

Results

Twelve out of the 13 patients in the study were available for follow-up with mean duration of 50 months. One patient died during the study period due to an unrelated cause. The mean HHS increased from 41 to 82 points. Eleven out of 12 acetabular components were well fixed and pelvic discontinuity healed in all patients.

Conclusion

Custom triflange PMI is an excellent option for management of complex and extensive acetabular defects with or without pelvic discontinuity.

Pelvic discontinuity: a challenge to overcome

Pelvic discontinuity (PD) has been a considerable challenge for the hip revision arthroplasty surgeon. However, not all PDs are the same. Some occur during primary cup insertion, resembling a fresh periprosthetic fracture that separates the superior and inferior portions of the pelvis, while others are chronic as a result of gradual acetabular bone loss due to osteolysis and/or acetabular implant loosening.In the past, ORIF, various types of cages, bone grafts and bone cement were utilized with little success. Today, the biomechanics and biology of PD as well as new diagnostic tools and especially a variety of new implants and techniques are available to hip revision surgeons. Ultraporous cups and augments, cup-cage constructs and custom triflange components have revolutionized the treatment of PD when used in various combinations with ORIF and bone grafts. For chronic PD the cup-cage construct is the most popular method of reconstruction with good medium-term results.Dislocation continues to be the leading cause of failure in all situations, followed by infection. Ultimately, surgeons today have a big enough armamentarium to select the best treatment approach. Case individualization, personal experience and improvisation are the best assets to drive treatment decisions and strategies. Cite this article: EFORT Open Rev 2021;6:459-471. DOI: 10.1302/2058-5241.6.210022.

Acetabulum Reconstruction with TantalumCup and Augments in Dysplastic Hip Type 4 using 3D Printing Technology

Introduction

Acetabular reconstruction in a patient with neglected DDH during complex primary total hip replacement is a challenging procedure to do. We are reporting assessment of acetabular defect in one such patient with pre-operative 3D printing, followed by reconstruction with trabecular metal shell and augments.

Case Report

A 32-year-old female with neglected DDH (Crowe's type 4) reported to us with pain, limp, and shortening of affected limb. Operated somewhere else with THR, she had a missing acetabular component and coral stem in situ at the time of presentation. Acetabular defect was assessed by 3D printing of pelvis following which acetabular reconstruction with tantalum cup and augments along with femoral stem revision was done.

Conclusion

This study confirmed the role of 3D printing pelvis model in meticulous pre-operative planning in patients with complex hip deformities. Reconstruction of acetabular defects with tantalum cup, and augments is a reasonable solution to achieve better function.

3D Printed Acetabular Components for Complex Revision Arthroplasty

Recent studies have shown high early failure rates with Cup Cage constructs in complex revision surgery for Paprosky 3B acetabular defects. As a result, the use of 3D printed custom-made acetabular components has become more common. In this case series, we present two cases that demonstrate the latest advancement in 3D printed implants for severe acetabular bone loss. The follow up was 3 and 7 years. Neither patient has undergone revision surgery of the acetabular component to date. One patient sustained a femoral peri-prosthetic fracture requiring plate fixation. This case study demonstrates that 3D printed implants have excellent intraoperative and immediate postoperative outcomes in revision surgery for severe acetabular bone defects.

Acetabular Revision With Intramedullary and Extramedullary Iliac Fixation for Pelvic Discontinuity

BACKGROUND

Parallel to the increase in revision hip procedures surgeons face more and more complex anatomical challenges with pelvic discontinuity (PD) being one of the worst-case scenarios. Here we report on our clinical results using an asymmetric acetabular component for the treatment of PD. The implant is armed in a monoblock fashion with an extramedullary iliac flange and provides the possibility to augment it with an intramedullary iliac press-fit stem.

METHODS

In a single-center retrospective cohort study we analyzed prospectively collected data of 49 patients (35 female, 14 male) suffering from unilateral periprosthetic PD treated with an asymmetric acetabular component between 2009 and 2017. The mean follow-up was 71 months (21-114). Complications were documented and radiographic and functional outcomes were assessed.

RESULTS

Kaplan-Meier analysis revealed a 5-year implant survival of 91% (confidence interval 77%-96%). The 5-year survival with revision for any cause was 87% (CI 74%-94%). The overall revision rate was 16% (n = 8). Two patients required acetabular component revision due to aseptic loosening. Four patients (8%) suffered from periprosthetic infection: one patient was treated with a 2-stage revision, and another one with resection arthroplasty. The other 2 patients were treated with debridement, irrigation, and exchange of the mobile parts. Of 6 patients (12%) suffering from hip dislocation, 2 required implantation of a dual mobility acetabular component. The mean Harris Hip Score improved from 41 preoperatively to 79 at the latest follow-up (P < .001).

CONCLUSION

Our findings demonstrate that an asymmetric acetabular component with extramedullary and optional intramedullary iliac fixation is a reliable and safe treatment method for periprosthetic PD resulting in good clinical and radiographic mid-term results.

Acetabular Distraction Technique for the Treatment of Chronic Pelvic Discontinuities: Excellent Short-Term Implant Survivorship and Good Clinical Outcomes

BACKGROUND

Pelvic discontinuity is a challenging complication in revision total hip arthroplasty. One technique that has garnered enthusiasm with limited data is acetabular distraction. Acetabular distraction provides stability via elastic recoil of the pelvis. The aim of this study is to report implant survivorship, radiographic results, clinical outcomes, and complications in the largest independent series of discontinuities treated with acetabular distraction.

METHODS

We retrospectively identified all revision total hip arthroplasties with a pelvic discontinuity between 2005 and 2017. Of the 162 patients, 31 were treated with distraction. Mean age was 67 years, with 71% female. Mean body mass index was 28 kg/m², and mean follow-up was 3 years.

RESULTS

The 2-year survivorship free from revision for aseptic loosening, re-revision for any reason, and reoperation were 97%, 93%, and 87%, respectively. There were 3 re-revisions including 1 for aseptic loosening, 1 conversion to a dual mobility for instability, and 1 two-stage exchange for infection. At last follow-up, 3 acetabular components did not have evidence of osteointegration. Only patients with osteointegration to both the ilium and ischium had evidence of a healed discontinuity. The mean Harris Hip Score improved from 43 preoperatively to 77 postoperatively (P < .0001). The most common complication was a partial sciatic nerve palsy that occurred in 4 patients.

CONCLUSION

In this series utilizing pelvic distraction, there was excellent 2-year survivorship free from revision for aseptic loosening. Despite several discontinuities persisting, 90% of patients had radiographic evidence of implant osteointegration, and clinical outcomes improved significantly. The most common complication was a partial sciatic nerve palsy.

LEVEL OF EVIDENCE

IV Case Series.

3D-Printed Modular Hemipelvic Endoprosthetic Reconstruction Following Periacetabular Tumor Resection: Early Results of 80 Consecutive Cases

BACKGROUND

Reconstruction with an endoprosthesis following pelvic tumor resection has increased over the years. However, the long-term results reflect a disappointing frequency of mechanical complications and failures. In an attempt to enhance implant fixation, an electron beam melting (EBM)-based modular hemipelvic endoprosthesis was introduced. Our aim was to explore the preliminary clinical outcomes for patients who have been managed with this prosthesis.

METHODS

We reviewed the records of 80 consecutive patients who had been managed at a single center between June 2015 and September 2017. Chondrosarcoma was the predominant diagnosis (31.3%). Osseous metastases were diagnosed in 16 patients (20.0%). The position of the reconstructed metallic acetabulum was measured on an anteroposterior pelvic radiograph. Bone ingrowth was evaluated in 2 samples harvested from patients with tumor recurrence.

RESULTS

After a median duration of follow-up of 32.5 months (range, 9 to 52 months), no acetabular component instability was detected on radiographs. Histological sectioning of specimens harvested from 2 patients with tumor recurrence showed bone trabeculae extending toward the implant and bone ingrowth within the porous network. At the time of the latest follow-up, 59 patients (73.8%) were alive with no evidence of disease, 5 patients (6.3%) were alive with disease, and 16 patients (20.0%) had died of disease. Local recurrence occurred in 9 patients (11.3%). The mean Musculoskeletal Tumor Society score at the time of the latest follow-up was 83.9% (range, 43% to 100%). Complications occurred in 16 patients (20%), with wound dehiscence being the most common complication (8 patients; 10%). No aseptic loosening was found. Five patients (6.3%) had deep infection, and 2 patients (2.5%) had dislocation.

CONCLUSIONS

The use of a 3-dimensional (3D)-printed modular hemipelvic endoprosthesis with a highly porous metal interface represents a potential choice as a pelvic endoprosthesis after internal hemipelvectomy for the treatment of a primary or metastatic tumor. These preliminary results demonstrate stable fixation with acceptable early functional and radiographic outcomes.

LEVEL OF EVIDENCE

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

Comparison of Porous Tantalum Acetabular Implants and Harrington Reconstruction for Metastatic Disease of the Acetabulum

BACKGROUND

The periacetabular region is a common location for metastatic disease. Although large lytic acetabular defects are commonly treated with a hip arthroplasty with a cemented component according to a Harrington-style reconstruction, the use of highly porous uncemented tantalum acetabular components has been described. Currently, there are no direct comparisons of these reconstructive techniques. The purpose of this study was to compare the outcomes of the Harrington technique and tantalum acetabular component reconstruction for periacetabular metastases.

METHODS

From 2 tertiary sarcoma centers, we retrospectively reviewed 115 patients (70 female and 45 male) with an acetabular metastatic defect who had been treated between 2002 and 2015 with a total hip arthroplasty using either the cemented Harrington technique (78 patients) or a tantalum acetabular reconstruction (37 patients). The mean patient age was 61 years, and the most common Eastern Cooperative Oncology Group status was 3 (39 patients). The mean follow-up for surviving patients was 4 years.

RESULTS

An additional surgical procedure was performed in 24 patients (21%). Harrington-style reconstructions were more likely to require a reoperation compared with tantalum reconstructions (hazard ratio [HR], 4.59; p = 0.003). The acetabular component was revised in 13 patients (11%); 5 patients (4%) underwent revisions that were due to loosening of the acetabular component. The 10-year cumulative incidence of revision of the acetabular component for loosening was 9.6% in the Harrington group and 0% in the tantalum group (p = 0.09). The mean Harris hip score significantly improved following reconstruction (31 to 67 points; p < 0.001), with no significant difference (p = 0.29) between groups.

CONCLUSIONS

In patients with periacetabular metastatic disease treated with total hip arthroplasty, an acetabular reconstruction strategy utilizing highly porous tantalum acetabular components and augments successfully provided patients with a more durable construct with fewer complications compared with the cemented Harrington-style technique.

LEVELS OF EVIDENCE

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

Cup-Cage Solution for Massive Acetabular Defects: A Systematic Review and Meta-Analysis

Our systematic review compiled multiple studies and evaluated survivorship and clinical outcomes of cup‐cage construct usage in the management of massive acetabular bone defects. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines. Various combinations of “acetabular”, “pelvis”, “cup cage” and their corresponding synonyms were used to search relevant articles in the Cochrane, EMBASE, and PubMed databases. Basic information of the functional scores, implant revision rate, and complication rate were selected as outcomes for analysis. Finally, a total of 11 articles published between 1999 and 2019 were selected, which include 232 patients with an average age of 68.5 years (range, 30–90). The mean follow‐up period was 48.85 months (range, 1–140). Our study shows that the cup‐cage construct has a good clinical outcome with a low revision rate and a low complication rate. Improved clinical outcomes of cup‐cage constructs were seen with a revision rate of 8% and an all‐cause complication rate of 20%. The most commonly reported complication was dislocation, followed by aseptic loosening, infection, and nerve injuries. In summary, it is a promising method for managing large acetabular bone defects in total hip revision.

Three-dimensional-printing Technology in Hip and Pelvic Surgery: Current Landscape

The use of three-dimensional (3D) printing is becoming more common, including in the field of orthopaedic surgery. There are currently four primary clinical applications for 3D-printing in hip and pelvic surgeries: (i) 3D-printed anatomical models for planning and surgery simulation, (ii) patient-specific instruments (PSI), (iii) generation of prostheses with 3D-additive manufacturing, and (iv) custom 3D-printed prostheses. Simulation surgery using a 3D-printed bone model allows surgeons to develop better surgical approaches, test the feasibility of procedures and determine optimal location and size for a prosthesis. PSI will help inform accurate bone cuts and prosthesis placement during surgery. Using 3D-additive manufacturing, especially with a trabecular pattern, is possible to produce a prosthesis mechanically stable and biocompatible prosthesis capable of promoting osseointergration. Custom implants are useful in patients with massive acetabular bone loss or periacetabular malignant bone tumors as they may improve the fit between implants and patient-specific anatomy. 3D-printing technology can improve surgical efficiency, shorten operation times and reduce exposure to radiation. This technology also offers new potential for treating complex hip joint diseases. Orthopaedic surgeons should develop guidelines to outline the most effective uses of 3D-printing technology to maximize patient benefits.

Cup-cage construct for massive acetabular defect in revision hip arthroplasty- A case series with medium to long-term follow-up

OBJECTIVE

Cup-cage reconstruction has emerged as a possible solution for managing massive acetabular defects with a few existing studies reporting encouraging results at mid-term follow-up. We present our experience with this unitised construct.

METHOD

Six patients (7 hips) with a mean age of 76 years (73-81) were revised due to catastrophic aseptic failure of a primary cup implanted 10-19 years previously, having a Paprosky type 3B acetabular defect.

RESULTS

At a mean follow-up of 72 months (63-140) no cases have required re-revision. Oxford Hip Scores improved from an average of 8 (1-17) preoperatively to an average of 36 (18-45) at the last follow-up. WOMAC scores preoperatively averaged 76 (49-96) and postoperatively averaged 26.5 points (0-69) at the last follow-up. SF-12 scores improved in both components. One patient showed non-progressive osteolysis around the ischial flange and one had less than 5 mm migration of the construct. One patient died of unrelated causes.

CONCLUSION

Our study presents one of the longest follow-up of cup-cage construct and supports the previously reported good results; it encourages the use of this construct in reconstruction of massive acetabular defect, with or without pelvic discontinuity.

Inferior extended fixation utilizing porous titanium augments improves primary anti-rotational stability of the acetabular component

BACKGROUND

The primary anti-rotational stability is critical to preventing cup tilting failure following revision total hip arthroplasty, but is frequently compromised by severe ischial bone loss. A novel technique of "inferior extended fixation" was introduced by securing a porous metal augment into the deficient ischium. This study evaluated the effect of this technique on primary anti-rotational stability in revision total hip arthroplasty.

METHODS

Composite hemipelvis specimens, acetabular components and "lotus" augments were used to simulate total hip arthroplasty surgeries. Three different cementless operative settings of cup implantation were simulated: (1) native ischium without defects; (2) ischium with a defect not reconstructed; (3) ischial defect reconstructed with inferior extended fixation using a lotus augment. Lever-out testing was used to examine primary anti-rotational stability, which was measured as interface stiffness and yield moment.

FINDINGS

Compared with the native ischium setting, the mean interface stiffness decreased by 53.1% in the ischial defect setting (p < 0.001). In the inferior extended fixation setting, the mean value was 110% greater than that in the ischial defect setting (p = 0.014), and comparable to that in the native ischium setting (p = 1). Similar results were observed for the yield moment (declined by 63.1%, p < 0.001; 200% higher, p < 0.001; and p = 0.395; respectively).

INTERPRETATION

In revision total hip arthroplasty with severe ischial defects, inferior extended fixation with a lotus porous titanium augment restores anti-rotational stability of the acetabular component to the level of that with a native ischium, which provides the mechanical environment for bone ingrowth and prevents cup tilting failure.

The mid-long term results of reconstructional cage and morselized allografts combined application for the Paprosky type III acetabular bone defects in revision hip arthroplasty

Background

Severe acetabular bone defects is a complex problem in revision hip arthroplasty, cage is one of the reconstruction options. The purpose of this study is to report the mid-long term clinical and radiographic results of Paprosky type III acetabular bone defects revised with reconstructional cage and morselized allogeneic cancellous bone graft without impaction.

Methods

We retrospectively analyzed 28 patients who underwent revision hip arthroplasty with reconstructional cage and allogeneic cancellous bone graft between January 2007 and January 2016. There were 13 Paprosky type IIIA bone defect patients and 15 Paprosky type IIIB bone defect patients and 4 patients of the 15 were also with pelvic discontinuity. Clinical assessment included Harris Hip Score (HHS) and Short Form-12 (SF-12). Radiographic assessment included center of rotation, cage migration, and bone graft incorporation.

Results

All patients were followed up with a mean follow-up of 79.5 months (range 38–141), HHS improved from 31.4 (13–43) points preoperatively to 84.6 (55–94) points at last follow-up and SF-12 also improved significantly. There was 1 re-revision for the cage loosening and screw breakage at 61 months after surgery, and 2 patients had nonprogressive radiolucency in zone III and the junction of zone II and zone III at the bone implant interface.

Conclusion

The reconstructional cage combining with morselized allografts without impaction achieves a good result with a high complete allograft incorporation rate in Paprosky type III acetabular bone defects.

Survivorship and Clinical Outcomes of Custom Triflange Acetabular Components in Revision Total Hip Arthroplasty: A Systematic Review

BACKGROUND

Several studies have evaluated the survivorship and clinical outcomes of custom triflange acetabular component (CTAC) usage in complex acetabular revision; however, there remains no consensus on the overall performance of this custom implant design. We therefore performed a systematic review of the literature in order to examine survivorship and complication rate of CTAC usage.

METHODS

A systematic review of the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed. A comprehensive search of PubMed, MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews was conducted for English articles using various combinations of the keywords "custom triflange," "custom-made triflange," "acetabular triflange," "THA," "THR," "revision," "bone loss," "bone defect," and "pelvic discontinuity."

RESULTS

In all, 17 articles met our inclusion criteria. A total of 579 CTACs were implanted. The all-cause revision-free survivorship was 82.7%. The overall complication rate was 29%. Dislocation and infection were the most common complications observed with an incidence of 11% and 6.2%, respectively. Nerve injuries following CTAC placement had an incidence of 3.8%. The incidence of CTAC aseptic loosening was 1.7%. Overall, patients had improved outcomes as documented by postoperative hip scores.

CONCLUSION

Based on the current data, CTACs have a high complication rate but remain an efficacious treatment option in complex acetabular reconstructions. When dealing with patients with significant acetabular bone loss for revision total hip arthroplasty, surgeons should continue to consider CTACs as a viable option but educate patients as to the increased risk of postoperative complications and reoperations.

The Lawrence D. Dorr Surgical Techniques & Technologies Award: Why Are Contemporary Revision Total Hip Arthroplasties Failing? An Analysis of 2500 Cases

BACKGROUND

As revision implants and techniques have evolved and improved, understanding why contemporary revision total hip arthroplasties (THAs) fail is important to direct further improvement and innovation. As such, the goals of this study are to determine the implant survivorship of contemporary revision THAs, as well as the most common indications for re-revision.

METHODS

We retrospectively reviewed 2589 aseptic revision THAs completed at our academic institution between 2005 and 2015 through our total joint registry. Thirty-nine percent were isolated acetabular revisions, 22% isolated femoral revisions, 18% both component revisions, and 21% head/liner component exchanges. The mean age at index revision THA was 66 years, and 46% were male. The indications for the index revision THA were aseptic loosening (21% acetabular, 15% femoral, 5% both components), polyethylene wear and osteolysis (18%), instability (13%), fracture (11%), and other (17%). Mean follow-up was 6 years.

RESULTS

There were 211 re-revision THAs during the study period. The overall survivorship free of any re-revision at 2, 5, and 10 years was 94%, 92%, and 88%, respectively. The most common reasons for re-revision were hip instability (52%), peri-prosthetic fracture (11%), femoral aseptic loosening (11%), acetabular aseptic loosening (9%), infection (6%), polyethylene wear (3%), and other (8%).

CONCLUSION

Compared to historical series, the 88% survivorship free of any re-revision at 10 years in a revision cohort at a referral center is notably improved. As implant fixation has improved, aseptic loosening has become much less common after revision THA, and instability has come to account for more than half of re-revisions.

A single centre study of 41 cases on the use of porous tantalum metal implants in acetabular revision surgery

Background

This study aims at investigating cup survival of porous tantalum revision cups and identifies risk factors for failure.

Methods

We retrospectively reviewed 41 patients treated between 2010 and 2012. Main indications were aseptic loosening in 83% and two-stage exchange after periprosthetic joint infection in 17% of cases. Mean follow-up period was 72 months. Femoral megaprostheses were used in 13% of cases. Most defects were classified as Paprosky 3b (29%). Function was assessed using the Harris Hip score.

Results

Aseptic cup survivorship was 80% at 104 months (95% Confidence Interval 67.4–92.4). Overall implant survival was 73%. Major bone loss defects (Paprosky types 2c to 3b) were associated with a significantly higher rate of failure than minor defects (P = 0.002). There were eight cases of aseptic loosening (19.5%) and two of infection (4.9%). Previous surgeries, indication for acetabular revision, patient-related risk factors and use of megaprostheses did not significantly influence implant survival. The Harris Hip Score improved from a median of 40 (Interquartile range 31–45) to 82 (interquartile range 65–88) postoperative (P < 0.0001).

Conclusions

In summary, the use of porous tantalum metal implants in acetabular revision surgery achieves good to excellent short- term and mid-term functional results and an acceptable complication rate relative to the extent of defect and previous surgery. However, one should be aware of potential limitations of the implants in addressing large defects and discontinuity.

The augment-and-modular-cage revision system for reconstruction of severe acetabular defects-two-year clinical and radiographic results

PURPOSE

Acetabular revision of failed total hip arthroplasty (THA) is often associated with severe bone loss. Therefore, a variety of revision implant systems has been developed during recent years, with the augment-and-modular-cage system being one of the newest additions to this portfolio. Together with biologic downsizing by means of impaction bone grafting, this uncemented system promises a high modularity and versatility to treat all acetabular defects up to Paprosky types IIIa and IIIb without pelvic discontinuity. The aim of the present study was to evaluate first short-term results of its clinical application, both clinical functional and patient-reported as well as radiographic.

METHODS

Forty-four patients (28 female, 16 male, mean age 70.9 ± 11.5 years) could be followed for a mean of 26 ± 10 months after acetabular revision with a novel augment-and-modular-cage system. Indications for revision included aseptic loosening (68%), septic loosening (16%), or others (16%) with bone loss Paprosky IIa up to IIIb without discontinuity. The modified Harris Hip Score (mHHS) served as a primary outcome parameter. In addition, a number of patient-reported outcome measurements (PROMs) were collected including the Short Form 36 (SF-36), Hip disability and Osteoarthritis Outcome Score (HOOS), and Visual Analogue Scale for Hip Pain (VAS Hip) as well as overall satisfaction. Radiographic changes between the pre- and postoperative center of rotation (COR) and various criteria of implant failure served as secondary outcome parameters.

RESULTS

No patients were lost to follow-up. Two implant-associated complications (partial flange breakage) without a need for revision surgery were detected, which represent a failure rate of 4.5%. Functional outcome as measured by mHHS increased from 49.4 ± 2.9 pre-operatively to 74.4 ± 3.1 at the latest follow-up (p < 0.001). PROMs showed significant improvements in all pain-related categories, while other quality-of-life measurements only exhibited positive tendencies towards improvement. VAS Hip significantly improved from 6.5 ± 0.7 pre-operatively to 2.2 ± 0.6 at the latest follow-up (p < 0.001). Radiographic evaluation showed that reconstruction of the COR was possible, referenced to the contralateral side. The COR could be lateralized by 5.0 mm (n.s.) and caudalized by 10.3 mm (p < 0.001) comparing pre-operative and post-operative states, with complete osseointegration in 95% of the cases.

CONCLUSIONS

Treatment with the augment-and-modular-cage system significantly improved clinical functional and patient-reported outcomes in cases of acetabular revision after failed THA. In addition, a good reconstruction of the COR could also be achieved. Therefore, this highly modular system can be considered as an effective treatment option in almost all cases of acetabular bone loss except for those of pelvic discontinuity. It offers the unique possibility of intra-operative implant customization according to the existing bone defect and host bone quality.

The Utilization of Metal Augments Allows Better Biomechanical Reconstruction of the Hip in Revision Total Hip Arthroplasty With Severe Acetabular Defects: A Comparative Study

BACKGROUND

Reconstructing the normal hip biomechanics is important for a successful revision total hip arthroplasty (THA). Little is known about whether using metal augments in revision THA is biomechanically superior to traditional techniques.

METHODS

A retrospective review was conducted on 74 consecutive THAs revised using metal augments with a cementless hemispherical cup and 77 consecutive THAs revised using the jumbo cup, all with a minimum 2-year follow-up. Biomechanical parameters were measured before and immediately after the revision. Radiological and clinical outcomes at follow-ups were also evaluated.

RESULTS

The metal augment group had a reconstructed center of rotation (COR) that was 6.5 mm closer to the anatomic COR in height (P < .001), had 3.6 m smaller cup size (P < .001), and had 5.7 mm less head-cup difference (P < .001). Moreover, there was a reconstructed COR that was much closer to the anatomic COR (vertical distance: 1.8 vs 14.1 mm, P < .001; horizontal distance: -2.1 vs 7.9 mm, P = .013), had 4.1 mm greater femoral offset (P = .006), and had 8 mm less leg length discrepancy (P = .035) in the subgroup of Paprosky type III bone defects when compared to the jumbo cup group. All cup-augment constructs were radiologically stable with a higher mean postoperative Harris Hip Score (P = .012). One jumbo cup was radiologically unstable.

CONCLUSION

In revision THA, utilizing metal augments helps to restore the COR position more precisely, avoid using a larger cup, reduce head-cup difference, rebuild femoral offset, and decrease leg length discrepancy, particularly with Paprosky type III bone defects. Moreover, it provides satisfactory radiological and clinical outcomes in the short term.

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.

Acetabular reinforcement rings associated with allograft for severe acetabular defects

Acetabular revisions with severe bone defects can be challenging procedures. Several grading systems have been set into place to help the surgeon adequately gauge the degree of bone loss within the acetabulum. Internationally innovative research in orthopedics and bio-engineering has helped with progression of successful techniques and rings to re-establish the normal anatomy of the hip. The purpose of this review is to evaluate the outcomes of the different acetabular reinforcement rings in the setting of severe acetabular defects. A successive report of relevant data from the literature of multiple techniques will be provided. The procedures include the cup-cage, the Müller ring, the Ganz Ring, the Kerboull acetabular reinforcement device (KARD), the graft augmentation prosthesis (GAP) ring, and the Burch-Schneider ring. The main focus of this overview is rings only; other devices such as trabecular augments, custom-made cages, or oblong cups are not discussed. Furthermore, a special emphasis on the surgical technique of the KARD is also given. Procedures using these rings are usually associated with bone grafts either bulk or morselized. When considering the available data on these various rings used for reconstruction of the severely damaged acetabulum, the cup-cage, the KARD, and the Burch-Schneider ring appear to be reliable options for more successful long-term outcomes.

Cementation of a Dual Mobility Construct in Recurrently Dislocating and High Risk Patients Undergoing Revision Total Arthroplasty

BACKGROUND

Recurrent instability remains a challenge after revision total hip arthroplasty (THA). We report the outcomes of cementing a cementless dual mobility (DM) component into a stable acetabular shell for the treatment and/or prevention of instability in revision THA.

METHODS

Eighteen patients (18 THAs) undergoing revision THA with a specific monoblock DM construct cemented into a new acetabular component or an existing well-fixed component from 2011 to 2014 were retrospectively reviewed. Tumor prostheses and total femoral replacements were excluded. In 9 patients (50%), components were implanted specifically for recurrent dislocations. Mean age was 64 years; mean follow-up was 3 years. Patients underwent an average of 4 prior hip operations (range 2-6).

RESULTS

No cemented DM cups dissociated at the cement-cup interface. Three patients (17%) experienced a postoperative dislocation. One required a revision to constrained liner and 2 underwent open reduction with retention of the DM construct. Harris Hip Scores improved from 53 to 82 postoperatively (P < .001).

CONCLUSION

Cementation of a monoblock cup DM construct, an off-label use as the construct is not specifically made for cementation, into a well-fixed acetabular component provides an alternative to enhance prosthetic stability in (1) recurrently dislocating THAs with well fixed, well-positioned acetabular components and (2) complex acetabular reconstructions in which constraint should be avoided. While not a perfect solution in this series, DM constructs provide a number of advantages including no added constraint at the interface and a large effective femoral head to diminish prosthetic impingement.