Modulare Defektrekonstruktion beim Pfannenwechsel mit Abstützschale und metallischen Augmenten: „Cage-and-Augment“-System

Survival analysis of 3D printed acetabular implants in revision total hip arthroplasty associated with severe pelvic discontinuities

BACKGROUND

Surgeons still face difficulties when performing aseptic acetabular revision on patients with extensive defects. Advances in three-dimensional printing technology (3DP) have afforded to the surgeons to create a patient-specific implant matching the morphology and topography of the defect.

OBJECTIVE

The aim of the current research was to determine the survivorship in the treatment of acetabular bone defects with pelvic discontinuity (PD).

METHODS

In order to reconstruct Paprosky type III defects with PD, twenty-three patients underwent revision total hip arthroplasty (THA) utilizing 3D-printed implants (Mobelife). The primary outcomes were the implant-associated failure rate correlated with survivorship. As secondary variables, complications and the effect of age, sex, comorbidities, history of infections and the presence of other lower limb arthroplasties on a new revision were analyzed.

RESULTS

Patients were followed out to a mean of 67.22 ± 39.44 months (range, 0.9-127 months). Mobelife implant mean survival was 102.57 ± 9.90 months (95% CI 83.17-121.96). The cohort's implant one-year survival rate was 87%; at ten years, it dropped to 78.3%. There were four revisions: three due to periprosthetic joint infection (PJI) and one case due to aseptic loosening. Cox regression analysis did not identify any variable as predictor of failure.

CONCLUSION

The use of 3DP patient-specific acetabular components has shown encouraging results and it is a viable treatment option for addressing acetabular defects with combined PD in aseptic THA revision.

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 and defects : Trauma meets ortho]

BACKGROUND

Periprosthetic acetabular fractures are considered to be a severe and challenging complication in total hip arthroplasty. To date, there are no internationally applicable standardized recommendations which can assist orthopedic surgeons and trauma surgeons in the treatment of patients.

OBJECTIVE

The aim of this article is to report on the current state of knowledge on periprosthetic acetabular fractures, to present the commonly used classification systems and to demonstrate appropriate treatment algorithms together with personal experiences.

MATERIAL AND METHODS

A selective search of the existing literature was carried out and the commonly used classification systems and treatment options for periprosthetic acetabular fractures were compiled and are discussed in relation to the in-house cases.

RESULTS

The comparison of the classification systems showed that frequently only fractures which have a purely traumatic origin are included among periprosthetic acetabular fractures. Insufficiency fractures within the framework of acetabular defects, which also belong to the group of acetabular fractures, are frequently included in revision arthroplasty. The management of defects with appropriate implants represents a challenge. By the combination of osteosynthesis and implant replacement, the selection of implants can often be de-escalated.

CONCLUSION

Periprosthetic acetabular fractures represent a complex operation for both trauma surgeons and for specially trained orthopedic surgeons, which necessitate a high level of expertise. By the cooperation between trauma surgeons and orthopedic surgeons good treatment results can be achieved and recommendations for the selection of implants can be made.

[Strategies for cup revision]

Hip arthroplasty revision management can range from simple procedures using standard implants to complex surgical interventions requiring the combined use of revision cups, metal augments, bone grafts, and antiprotrusio cages. The adequate restoration of biomechanics and function of the hip joint with reconstruction of the original center of rotation can be challenging. We present an overview of various available techniques with the associated implant and anchoring strategies and the respective clinical results depending on the acetabular defect situation.

[Partial or full component exchange in hip revision? : The relevance of off-label use and mix & match]

Off-label use is frequently practiced in hip revision arthroplasty, as there may be indications for the application of implants for purposes outside the one the manufacturers intended (i.e. large bone and soft tissue defects, obesity). Patients may also benefit from selective application of mix & match in hip revision, when the exchange of one component only is necessary and the invasiveness of surgery can be reduced. Currently, there are no formal guidelines for these situations. Therefore, within a recent EFORT initiative, evidence- and consensus-based recommendations have been developed for the safe application of off-label use and mix & match in revision hip and knee arthroplasty.

EFORT recommendations for off-label use, mix & match and mismatch in hip and knee arthroplasty

Off-label use is frequently practiced in primary and revision arthroplasty, as there may be indications for the application of implants for purposes outside the one the manufacturers intended.

Under certain circumstances, patients may benefit from selective application of mix & match. This can refer to primary hip arthroplasty (if evidence suggests that the combination of devices from different manufacturers has superior results) and revision hip or knee arthroplasty (when the exchange of one component only is necessary and the invasiveness of surgery can be reduced).

Within the EFORT ‘Implant and Patient Safety Initiative’, evidence- and consensus-based recommendations have been developed for the safe application of off-label use and mix & match in primary as well as revision hip and knee arthroplasty.

Prior to the application of a medical device for hip or knee arthroplasty off-label and within a mix & match situation, surgeons should balance the risks and benefits to the patient, obtain informed consent, and document the decision process appropriately.

Nevertheless, it is crucial for surgeons to only combine implants that are compatible. Mismatch of components, where their sizes or connections do not fit, may have catastrophic effects and is a surgical mistake.

Surgeons must be fully aware of the features of the components that they use in off-label indications or during mix & match applications, must be appropriately trained and must audit their results.

Considering the frequent practice of off-label and mix & match as well as the potential medico-legal issues, further research is necessary to obtain more data about the appropriate indications and outcomes for those procedures.

Cite this article: EFORT Open Rev 2021;6:982-1005. DOI: 10.1302/2058-5241.6.210080

Tantalum Augments Combined with Antiprotrusio Cages for Massive Acetabular Defects in Revision Arthroplasty

Background

Tantalum components have gained popularity for the management of Paprosky type IIIA and IIIB defects during revision total hip arthroplasty. Although the use of antiprotrusio cages solely shows suboptimal results, there are certain defects that still require their use. We hypothesized that combining tantalum augments and an antiprotrusio cage would (1) improve radiographic stability, (2) enhance survivorship, (3) decrease complications, and (4) improve clinical outcomes.

Methods

We retrospectively reviewed 20 patients with Paprosky type IIIA or IIIB defects who underwent revision of the acetabular component with a highly porous tantalum augment and an antiprotrusio cage combination. Preoperative and postoperative radiographs, survivorship free from aseptic component revision, and the Harris Hip Score, Western Ontario and McMaster Universities Osteoarthritis Index, and Short Form-36 scores were analyzed. The mean follow-up was 2.8 years.

Results

At the most recent follow-up, no antiprotrusio cages had migrated and all tantalum augments had radiographic evidence of osseointegration. In addition, only 2 components were revised for aseptic etiologies and only 1 was loose. Both were revised secondary to failures of the inferior flange of the antiprotrusio cage. All clinical outcome scores significantly improved postoperatively. Finally, the risk of major postoperative complications was noted to be 10%.

Conclusions

In summary, a tantalum augment combined with an antiprotrusio cage in Paprosky IIIA and IIIB defects with divergent anatomy not amenable to a hemispherical socket provides a reliable technique to restore the anatomic hip center and prevent superior migration and provides a bony ingrowth surface. Longer term follow-up is required before the technique is widely adapted.

Level of Evidence

Level IV, therapeutic studies.

[Periprosthetic fractures of the acetabulum: revision endoprosthetics]

BACKGROUND

Periprosthetic acetabular fractures are an increasing severe complication in revision arthroplasty. A differentiation is made between periprosthetic acetabular fractures (acute/traumatic fractures) and insufficiency fractures (chronic fractures).

OBJECTIVE

This article introduces a novel treatment algorithm that provides assistance in therapeutic decision making for implant selection and the anchoring philosophy based on diagnostic decision criteria and the relevant load-bearing osseous structures, taking the defect situation into account.

MATERIAL AND METHODS

The article provides an overview of original and review articles.

RESULTS

The essential criteria for decisions in treatment planning are based on the stability of the primary cup, the load-bearing ability of the main anatomical structures and the resulting defect situation. For insufficiency fractures the reason for the revision and therefore the exclusion of periprosthetic joint infections (PJI) must additionally be considered. In the case of proven PJI a two-stage or multistage prosthesis exchange must be carried out. Based on the extent of apparent bony defects and pelvic discontinuity, the spectrum of treatment options ranges up to implantation of individual patient custom-made acetabular components.

DISCUSSION/CONCLUSION

This overview introduces a new treatment algorithm that provides assistance in decision making for traumatic periprosthetic acetabular fractures and insufficiency fractures. It also provides decision criteria for selection of implants and the surgical approach. Due to the complexity of revision arthroplasty often requiring specialized expertise in trauma and orthopedic surgery and experienced revision surgeons, the operative treatment of periprosthetic acetabular fractures should only be carried out in specialized orthopedic and trauma surgery centers with appropriate experience.

[Custom-made acetabular implants in revision total hip arthroplasty]

BACKGROUND

Management of acetabular bone loss is a demanding problem in revision total hip arthroplasty.

OBJECTIVES

The aim of this review is to introduce and discuss the results and the advantages and disadvantages of custom-made implants as a treatment option for severe acetabular bone defects.

MATERIALS AND METHODS

A selective review of the existing literature of custom made acetabular implants was performed on PubMed.

RESULTS

Studies showed good clinical and radiological outcomes of custom made acetabular implants and a survival rate of more than 90%.

CONCLUSION

Custom-made acetabular implants are a reliable treatment option for severe acetabular defects and allow the reconstruction of the centre of rotation of the hip. The costs of these implants are high and planning is time consuming.

Customised three-dimensional printed revision acetabular implant for large defect after failed triflange revision cup

Aseptic loosening is the most common cause for total hip arthroplasty revision. Acetabular cup revision is a significant challenge in the presence of a large bone defect. One of the options for cup revision in the presence of a large bone defect is the recently introduced customised three-dimensional (3D)-printed reconstruction. We present the case of a 68-year-old woman successfully treated with a customised revision acetabular implant for the failure of triflange cup in the presence of large acetabular defect. The modern orthopaedic surgeon must have full knowledge of customised 3D-printed reconstruction to have as a reserve solution for difficult hip revision surgery.

[Acetabular revision arthroplasty with a novel cementless augment-and-modular-cage system (MRS-C) : Surgical technique and preliminary clinical results]

OBJECTIVE

Optimal reconstruction of acetabular anatomy and primarily stable bridging even of large bone defects in hip revision surgery by intraoperative cementless application of highly modular components of the MRS-TITAN Comfort (MRS-C) system according to the augment-and-modular-cage principle.

INDICATIONS

Acetabular defect situations in hip revision surgery, hereditary/acquired acetabular deformities, severe secondary hip osteoarthritis.

CONTRAINDICATIONS

Extended periacetabular defects of the dorsal pillar, pelvic discontinuities, persisting posttraumatic or periprosthetic infections, lack of intraoperative bony anchorage options.

SURGICAL TECHNIQUE

Conventional positioning. Flexible selection of approach (posterolateral, anterolateral or transgluteal) to the hip joint, if possible using a previous approach. Implant removal, preparation and intraoperative acetabular defect evaluation. Optional impaction bone grafting for biological downsizing. Selection of modular components and augments depending on the defect. Preparation of the obturator foramen for anchorage of the caudal flange. Optional preparation of the os ilium for additional fixation of the cage with flanges. Fixation with polyaxial screws and selection of version/inclination of the cup component. Selection of the inlay (polyethylene/ceramic).

POSTOPERATIVE MANAGEMENT

Partial weight-bearing with 20 kg body-weight for 6 weeks with crutches. Prophylaxis for deep vein thrombosis and heterotopic ossification. Additional adapted antibiotic therapy in cases of infection.

RESULTS

A minimum 1‑year follow-up of 42 patients showed significant improvements of Harris Hip Scores (p < 0.0001), adequate reconstruction of the physiologic center of rotation (x-ray controlled in the vertical plane, referenced to the contralateral side), and a clear reduction of preoperative leg length discrepancies. No significant changes in range of motion. No implant-associated complications noted. Based on the short follow-up results, the implant proves as suitable for reconstruction of even large acetabular bone defects.

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.

Preliminary results of a 3D-printed acetabular component in the management of extensive defects

INTRODUCTION

The treatment of extensive bone loss and massive acetabular defects can be compounded by several challenges and pitfalls. The survivorship following acetabular revision with extensive bone loss is still unsatisfactory. The goal of the present study was to analyse the outcomes of 3D-printed patient-specific acetabular components in the management of extensive acetabular defects and combined pelvic discontinuity (PD).

METHODS

9 patients underwent revision THA using 3D-printed custom acetabular components to reconstruct extensive acetabular defects. The Paprosky classifications were determined in all patients. The primary outcome measure was the implant-associated failure rate.

RESULTS

1 out of 9 patients suffered an implant-associated complication (11%). The overall implant-associated survival rate was 89%. The overall complication rate was 56%.

CONCLUSIONS

The patient-specific acetabular component technique shows promise for the treatment of patients with severe acetabular defects in revision THA. Further research aimed at reducing costs and improving the complication rate are warranted.

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.

[Hip endoprosthetics in osteoarthritis after acetabular fractures]

BACKGROUND

The incidence of post-traumatic osteoarthritis after acetabular fractures is between 26 and 57%. With total hip arthroplasty (THA), affected patients can achieve a clear functional improvement and pain reduction if specific conditions are heeded.

OBJECTIVE

Depending on the degree and localisation of bone defects and deformities, scarring and the presence of remaining osteosynthesis material, different treatment strategies are available. This review gives an overview of current treatment strategies.

MATERIALS AND METHODS

Review of relevant clinical studies, meta-analyses and presentation of our own approach.

RESULTS

The best results regarding to implant survival and clinical outcome, comparable with THA in primary osteoarthritis, can be achieved, when cementless acetabular reconstruction with anatomical restoration of the hip's rotational center and sufficient mechanical support is obtained. Pre-operative planing based on a thorough radiographic examination is essential.

CONCLUSION

Althoug the postoperative complication rate is elevated after THA for posttraumatic arthritis after acetabular fractures compared with primary osteoarthritis, the overall functional results and implant survival are comparable.

[Arthroplasty for osteoarthritis secondary to hip dysplasia: Problem-oriented treatment strategies]

BACKGROUND

Because of anatomical variations total hip arthroplasty (THA) can be demanding in patients with osteoarthritis secondary to hip dysplasia.

OBJECTIVES

Depending on the degree of bony deformation, hip dislocation and soft tissue alteration numerous treatment strategies are available. This review describes current approaches that address frequent deformities.

MATERIALS AND METHODS

Review of relevant clinical studies, meta-analyses, and presentation of our own approach.

RESULTS

Pre-operative planning (based on a thorough clinical and radiographic examination) is essential. Acetabular reconstruction close to the primary acetabulum should always be intended. Roof augmentation and/or cup medialization can support stable bony implant fixation. Subtrochanteric shortening osteotomy of the femur is a demanding but reliable technique that avoids nerve damage in cases where inappropriate lengthening would be necessary (i.e., high riding dislocation).

CONCLUSIONS

Although the post-operative complication rate is elevated after THA for dysplastic hips compared with primary osteoarthritis, the overall functional results and implant survival are comparable.