Acetabular distraction

Acetabular Distraction: Promising 5-Year Outcomes for the Treatment of Chronic Pelvic Discontinuity

BACKGROUND

Severe acetabular bone loss encountered during revision total hip arthroplasty (THA) poses a clinical challenge. In cases involving pelvic discontinuity, where the ilium is separated superiorly from the inferior ischiopubic segment through the acetabulum, acetabular distraction may be used to restore the biomechanics of the hemipelvis. This technique allows for correct sizing of the acetabulum, and the subsequent peripheral distraction and medial compression at the discontinuity provide initial mechanical stability and biological fixation as bone in growth occurs. Accordingly, this study aimed to assess long-term 5-year outcomes following acetabular distraction across 2 institutions.

METHODS

We retrospectively identified all patients who underwent revision THA in which the acetabular distraction technique was performed for the treatment of chronic pelvic discontinuity between 2002 and 2018. Demographic, operative, and clinical postoperative data were collected. Clinical endpoints included postoperative radiographic outcomes, complications requiring additional surgery, and reoperation for all causes. Only patients who had a minimum 5-year follow-up were included in this study.

RESULTS

A total of 15 patients (Paprosky IIC: one patient, 6.7%; Paprosky IIIA: 5 patients, 33.3%; Paprosky IIIB: 9 patients, 60%) who had a mean follow-up time of 9 years (range, 5.1 to 13.5) were analyzed. Porous tantalum augments were used in 11 (73.3%) cases to primarily address posteriorsuperior defects (100%). There were 4 (26.7%) patients that required reoperation, only 2 of which were for indications related to the acetabular construct, leading to an overall survivorship of 86.7%. Both patients had a prior revision THA before the implementation of the distraction technique. Evidence of bridging callus formation was reported radiographically for 14 (93.3%) patients at the time of the last clinical follow-up.

CONCLUSIONS

For patients who have chronic pelvic discontinuity, acetabular distraction shows promising long-term outcomes. Even so, larger multi-center studies are needed to better support the efficacy of this technique.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Acetabular Distraction Technique: A Multicenter Study With a Minimum 2-Year Radiographic Follow-Up

BACKGROUND

Chronic pelvic discontinuity is a challenge during revision total hip arthroplasty due to the loss of structural continuity of the superior and inferior aspects of the acetabulum from severe acetabular bone loss. Acetabular distraction provides an alternative surgical treatment by stabilizing the acetabular component through elastic recoil of the pelvis, which may be supplemented with modular porous augments for addressing major acetabular defects. This study reports 2-year radiographic findings following acetabular distraction for the treatment of chronic pelvic discontinuity.

METHODS

Patients undergoing acetabular distraction performed by 5 surgeons from 2002 to 2021 were identified across 5 institutions. Demographic, surgical, and postoperative outcomes, including radiographic component stability, were recorded. There were 53 of 91 (58.2%) patients (5 deceased, 33 lost to follow-up) consisting of 4 Paprosky IIC (7.5%), 8 Paprosky IIIA (15.1%), and 41 Paprosky IIIB (77.4%) defects included, with a mean follow-up time of 4.8 years (range, 2 to 13.5). Modular porous augments were used in 33 (62.3%) cases. Failure was defined as a subsequent revision of the acetabular construct.

RESULTS

Among the 13 (24.5%) patients who returned to the operating room, 6 (46.2%) had a prior history of revision total hip arthroplasty before undergoing acetabular distraction. Only 5 (9.4%) patients underwent acetabular revision following acetabular distraction, leading to an overall cup survivorship of 90.6%. Of the remaining 48 patients, 46 (95.8%) had evidence of radiographic bridging callus of the chronic pelvic discontinuity at their last clinical follow-up.

CONCLUSIONS

To our knowledge, in the largest series to date, acetabular distraction has proven to be a viable treatment for acetabular bone loss with a chronic pelvic discontinuity, with excellent early survivorship and radiographic evidence of bridging callus. Future studies with longer follow-ups are needed to further monitor the efficacy of this technique.

LEVEL OF EVIDENCE

Level III, Retrospective Comparative Study.

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.

Medial wall reconstruction using metal disc augments in revision total hip arthroplasty

PURPOSE

Medial acetabular bone defects are frequently encountered in revision total hip arthroplasty (THA), but few studies have focused on their reconstruction. This study aimed to report the radiographic and clinical results after medial acetabular wall reconstruction using metal disc augments in revision THA.

METHODS

Forty consecutive revision THA cases using metal disc augments for medial acetabular wall reconstruction were identified. Post-operative cup orientation, the centre of rotation (COR), stability of acetabular components and peri-augments osseointegration were measured. The pre-operative and post-operative Harris Hip Score (HHS) and Western Ontario and McMaster Universities Arthritis Index (WOMAC) were compared.

RESULTS

The mean post-operative inclination and anteversion were 41.88 ± 6.70° and 16.73 ± 5.35°, respectively. The median vertical and lateral distance between the reconstructed CORs and the anatomic CORs were -3.45 mm (interquartile range [IQR]: -11.30 mm, -0.02 mm) and 3.18 mm (IQR: -0.03 mm, 6.99 mm). Thirty-eight cases completed the minimum two year clinical follow-up, whereas 31 had a minimum two year radiographic follow-up. Acetabular components were radiographically stable with bone ingrowth in 30 cases (30/31, 96.8%) while one case was classified as radiographic failure. Osseointegration around disc augments was observed in 25 of 31 cases (80.6%). The median HHS improved from 33.50 (IQR: 27.50-40.25) pre-operatively to 90.00 (IQR: 86.50-96.25) (p < 0.001), whereas the median WOMAC significantly improved from 38.02 (IQR: 29.17-46.09) to 85.94 (IQR: 79.43-93.75) (p < 0.001).

CONCLUSION

In revision THA with severe medial acetabular bone defect, disc augments could provide favorable cup position and stability, peri-augments osseointegration, with satisfactory clinical scores.

Extended Fixation for Paprosky Type III Acetabular Defects in Revision Total Hip Arthroplasty with a Minimum Follow-Up of 2 Years

OBJECTIVE

Revision of total hip arthroplasty for patients with severe acetabular bone defects is challenging. This study aims to report the minimum 2 years outcome of the iliac extended fixation technique in patients with Paprosky type III acetabular defects.

METHODS

Fifty-seven revision total hip arthroplasty patients were retrospectively reviewed who underwent reconstruction with the concept of iliac extended fixation from 2014 to 2017 in our hospital. We proposed a new concept of "iliac extended fixation" in revision total hip arthroplasty as fixation extending superiorly 2 cm beyond the original acetabular rim with porous metal augments, which was further classified into intracavitary and extracavitary fixation. Patients were assessed using the Harris Hip Score and the Western Ontario and McMaster Universities Osteoarthritis Index Score. Radiographs and patient-reported satisfaction were assessed.

RESULTS

At an average follow-up of 63 months (range 25-88 months), the postoperative Harris Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index scores were significantly improved at the last follow-up (p < 0.001). The center of rotation was significantly improved (p < 0.05). Fifty-three (93.0%) patients were satisfied with the outcome. The extracavitary iliac extended fixation group had higher rate of osteointegration in zone 1A (the superior lateral zone) than the intracavitary iliac extended fixation group (82.3% vs 55.0%, p = 0.015), and significantly more horizontal screws fixation (5.1 ± 24.7° vs 42.3 ± 36.8°, p < 0.001).

CONCLUSION

Intracavitary and extracavitary iliac extended fixation with porous metal augments and cementless cups are effective in reconstructing severe superior acetabular bone defects. The difference in screw direction might reflect the different biomechanics of augment fixation.

Feasibility and preliminary efficacy of tantalum components in the management of acetabular reconstruction following periacetabular oncologic resection in primary malignancies

Background

The aim of the study was to investigate the feasibility and preliminary efficacy of tantalum components utility in the reconstruction of acetabular defects following periacetabular oncologic resection of primary malignancies.

Methods

We prospectively collected a consecutive of 15 cases that were treated with tantalum components for acetabular reconstruction after periacetabular oncologic resection from January 2018 to December 2018. The cohort included 8 male and 7 female patients, with a mean age of 47.6 years (range, 33 to 67 years). Pathology types: chondrosarcoma (n = 9), malignant bone giant cell tumor (n = 3) and osteosarcoma (n = 3). Clinical outcomes, functional and radiographic results were recorded in detail for analysis.

Results

Patients received planned oncologic resection and tantalum components reconstruction without casualty; they were followed up with a mean of 39.7 months (35–45 months). The mean operation time was 4.0 h (3.0–6.0 h), and the mean blood loss was 1260 ml (800–2200 ml). Functional outcomes were assessed by MSTS-93 scale, with an average of 21.8 (12.0–26.0 scores), among which 3 cases were excellent, 11 were good and 1 was fair. The mean Harris Hip Score was 79.1scores (46.0–92.0 scores) at 1-year follow-up postoperatively. 3(3/15, 20.0%) cases experienced postoperative complications: 2 cases with hip dislocation received closed reduction under general anesthesia and were fixed with hip joint abduction braces for 6 weeks; one case had a superficial infection and received debridement with a delayed wound healing. Oncologic prognosis: one case relapsed at 8-month follow-up and received hemi-pelvic amputation; and another osteosarcoma patient experienced relapse with pulmonary metastasis and received further chemotherapy. No prosthetic loosening, displacement or fracture occurred during the follow-up period.

Conclusion

Preliminary results suggested that the use of tantalum components in the management of acetabular reconstruction following periacetabular oncologic resection provided reasonable improvement on functional outcomes and early stability of the prostheses. Porous tantalum components are conducive to bony ingrowth, which is a potential alternative to various existing reconstruction techniques to achieve better functional outcomes.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Acetabular Peri-Prosthetic Fractures—A Narrative Review

Acetabular peri-prosthetic fractures are rare but their incidence is rising due to the increased prevalence of total hip arthroplasty, the increasing life expectancy and the growing functional demand of an ageing population, the incidence of primary total hip arthroplasty is increasing. They are either intra-operative or post-operative and have various aetiologies. Several factors such as implant stability, bone loss, remaining bone stock, fracture pattern, timing, age and co-morbidities of the patients must be considered for adequate treatment. To date, the literature on this subject has been sparse and no universally recognized treatment algorithm exists. Their rarity makes them a little-known entity and their surgical management represents a challenge for most orthopaedic surgeons. This review aims to present an update on epidemiology, the diagnostic work up, existing classification systems, surgical approaches and therapeutic options for acetabular peri-prosthetic fractures.

Complex Reconstruction for Acetabular Pathologic Fracture in Unusual Chondroblastoma With Aneurysmal Bone Cyst

Treating bone loss with complex arthroplasty poses a significant challenge for the arthroplasty surgeon. When considering a reconstructive case after pathologic fracture and oncologic excision, a multidisciplinary approach with reliance on arthroplasty principles is critical. An 18-year-old patient presented with a complex acetabular pathologic fracture through a chondroblastoma with a secondary aneurysmal bone cyst. An outside institution performed a biopsy and placed a hip-spanning external fixator. Multidisciplinary planning led to tumor excision, complex acetabular arthroplasty reconstruction including structural bone grafting, and internal fixation. At the third year of follow-up, there was no evidence of mechanical loosening of the hip arthroplasty, reoperation, or tumor recurrence. The structural graft was completely osseointegrated, confirmed by a computed tomography scan obtained at 2 years postoperatively. This report demonstrates an unusual location of chondroblastoma, presenting with acetabular fracture definitively treated with complex multidisciplinary reconstruction leading to an excellent outcome in a young patient.

Treatment of Severe Acetabular Bone Loss Using a Tantalum Acetabular Shell and a Cemented Monoblock Dual Mobility Acetabular Cup

As the number of revision total hip arthroplasty increases, innovative solutions to complex problems are needed to address challenges posed by these complex cases. Severe acetabular bone loss, including cases of pelvic discontinuity, is a notable challenge with few solutions. Hip instability after revision arthroplasty remains one of the leading causes of revision and patient morbidity. The use of pelvic distraction and a press-fit tantalum shell for chronic discontinuity and posterior column open reduction and internal fixation with acetabular revision for acute pelvic discontinuity have previously been described. Similarly, dual mobility articulations have demonstrated long-term success in minimizing instability after revision total hip arthroplasty with good long-term survivorship. Here, the authors present a surgical technique in the management of Paprosky types 2 and 3 acetabular defects often with pelvic discontinuity using a tantalum shell in combination with cemented dual mobility liner to increase the stability of the joint. Custom screw placement is facilitated with the use of a metal cutting burr, both on the back table and in situ. The dual mobility liner is cemented, thus allowing for independent positioning of the acetabular implant and bearing surface. This technique has been successfully used in 19 patients with encouraging short-term results.

Acetabular distraction hip arthroplasty in neglected transverse and T-shape acetabular fractures : a different application

Neglected acetabular fractures are often challenging to treat. The aim of this study is to highlight the technique of acetabular distraction with porous metal cup as a viable technique to address such complex cases. This is a prospective study of seven patients who had neglected acetabular fracture or fracture non-union that were managed with total hip arthroplasty using acetabular distraction and porous metal cup with cemented liner. The average age of the patients was 51 years (range 36-58 years). Average time of follow up was 18 months (range 12-36 months). Radiological results at latest follow up and by comparing serial radiographs showed that all cases had a well-fixed implant construct without evidence of loosening or malorientation. Average Harris hip score pre-operatively was 46, which improved to an average of 84 post-operatively. Our study shows that total hip replacement using acetabular distraction with porous metal cup provide early good results in reconstruction of acetabular bony deficiencies due to neglected acetabular fracture.

Dual Mobility Reduces Dislocations-Why I Use It in All Revisions

BACKGROUND

Instability remains the most common complication after revision total hip arthroplasty (THA) and presents a unique treatment dilemma for the orthopedic surgeon. Dual mobility (DM) bearing articulations have been used in France since the 1970s, but have only become more widely adopted in the United States over the last decade. The purpose of this symposium was to discuss the role for DM bearings in revision THA.

METHODS

We reviewed the existing literature on outcomes after DM bearing articulations in revision THA. We also report several case examples of the use of DM in difficult revision THA cases, including acetabular bone loss, failed constrained liner, and adverse local tissue reaction. Finally, we briefly discuss the limitations associated with the use of DM.

RESULTS

Several large retrospective series demonstrate that DM bearings reduce the incidence of dislocation after revision THA when compared with conventional single bearing THA. Specific complications related to DM bearings including polyethylene wear, loosening, intraprosthetic dislocation, and corrosion remain a concern, but appear to have drastically improved over time with modern implant designs.

CONCLUSION

Contemporary DM designs have been established as an effective bearing option to reduce instability in revision THA, although concerns do exist. High-quality prospective studies are necessary to further define the role this bearing option has in the coming years.

Staged Total Hip Arthroplasty: A Novel Technique in Managing Native and Periprosthetic Acetabular Insufficiency

Background

There is no consensus on how to best address acetabular insufficiency. Several described techniques have a high rate of loosening and most rely on fixation to intact innominate bones. They also require extensive exposure and expensive implants. We present a novel technique for acetabular insufficiency management including discontinuity and a series with mean 6.5-year follow-up.

Material and Methods

After exposure, a femoral neck osteotomy is made, or the femoral component is removed. Bone graft is reverse reamed into the defect, and a porous coated acetabular shell is implanted with screws for supplemental fixation. In 3-6 months, after defect healing, the femoral component is implanted. All staged total hip arthroplasties for pelvic discontinuity from 2010 to 2015 by a single provider with minimum 5-year follow-up were identified. Implant survivorship, Merle d’Aubinge, and visual analog scale scores as well as complications were recorded.

Results

Nine patients were identified with mean 80.8-month follow-up (62-129). Merle D’Aubinge scores improved from 5.6 (4-8) to 15.3 (14-18), and Visual analog scale scores improved from 7.2 (6-9) to 0.8 (0-2). All implants were retained, and all patients were ambulatory at the terminal follow-up. There were 2 greater trochanter fractures, one calcar fracture managed with cerclage, and one patient developed heterotopic ossification.

Conclusion

Staged total hip arthroplasty can be used to address pelvic discontinuity with excellent short- to mid-term outcomes. This technique allows for a more limited exposure and the use of primary hip implants. Fixation is by ingrowth and does not rely on intact pelvic architecture.

Custom triflange revision acetabular components for significant bone defects and pelvic discontinuity: Early UK experience

Aims

We report our early experience in acetabular reconstruction for significant bone loss and pelvic discontinuity using custom triflange acetabular components.

Patients and methods

Retrospective consecutive review of all patients treated at our specialist tertiary unit with significant acetabular defects (Paprosky 3A/3B) and pelvic discontinuity who were reconstructed with custom triflange implants. The primary outcomes were radiographic failure and complications.

Results

17 patients (17 hips) were included; 3 males/14 females with a mean age of 72 years (range 61-83). The average follow-up was 3.6 years (2-7 years). Bony defects were Paprosky 3B in 13/17 hips (76%) with pelvic discontinuity encountered in the majority of cases 15/17 hips (88%) and intra-pelvic failed components in 11/17 (64%). At final follow up, no radiographic failures were observed although three patients developed complications (17.6%); haematoma requiring washout out; intra-operative ilium fracture; and recurrent dislocation in one patient.

Conclusions

Our experience suggest that acceptable outcomes can be achieved with custom implants for this group of challenging patients, although longer follow up is needed to monitor future implants' failure.

Total hip arthroplasty in acetabular fractures

Total Hip Arthroplasty (THA) is a well-accepted treatment for established hip arthritis following acetabular fractures. If a conservatively managed or operated case progresses to non-union/mal-union failing to restore the joint integrity, it may eventually develop secondary arthritis warranting a total hip arthroplasty. Also, in recent years, acute total hip arthroplasty is gaining importance in conditions where the fracture presents with pre-existing hip arthritis, is not amenable to salvage by open reduction and internal fixation, or, a poor prognosis is anticipated following fixation. There are several surgical challenges in performing total hip arthroplasty for acetabular fractures whether acute or delayed. As a separate entity elderly patients pose a distinct challenge due to osteoporosis and need stable fixation for early weight bearing alleviating the risk of any thromboembolic event, pulmonary complications and decubitus ulcer. The aim of surgery is to restore the columns for acetabular component implantation rather than anatomic fixation. Meticulous preoperative planning with radiographs and Computed Tomography (CT) scans, adequate exposure to delineate the fracture pattern, and, availability of an array of all instruments and possible implants as backup are the key points for success. Previous implants if any should be removed only if they are in the way of cup implantation or infected. Press fit uncemented modern porous metal acetabular component with multiple screw options is the preferred implant for majority of cases. However, complex fractures may require major reconstruction with revision THA implants especially when a pelvic discontinuity is present.

Acetabular reconstruction using porous metallic material in complex revision total hip arthroplasty: A systematic review

Bone defects during acetabular revision of total hip arthroplasty raise a problem of primary fixation and of durable reconstruction. Bone graft with direct cemented fixation or in a reinforcement cage was long considered to be the gold standard; however, failures were reported after 10 years' follow-up, especially in segmental defect of the roof or pelvic discontinuity. In such cases, metallic materials were proposed, to ensure primary fixation by a roughness effect with added screws, and especially to avoid failure due to bone resorption in the medium term. We report a systematic literature analysis, addressing the following questions: (1) What materials are available and can be used with dual mobility (DM) designs? Apart from Trabecular Metal™ (TM), in which a DM cup can be cemented for sizes≥56mm, 4 other porous metals are available (Tritanium™, Trabecular Titanium™, Conceloc™, Regenerex™ and Gription™) although only the first 3 can be associated to DM. (2) Can the cost of these materials be estimated and compared to allograft with reinforcement cage? Considering simply the cost of the implant itself, compared to reconstruction by graft+cage+cemented cup (€2100), TM incurs an extra cost of €534, but with €1434 not covered by the French healthcare insurance. The cost of custom implants (apart from hemi-pelvis) ranges between €4200 and €8500, with only €4749 cover. (3) Do metallic materials ensure better survival than allograft+cage, according to severity of bone loss? Metallic reconstruction is claimed (with a low level of evidence) to reduce the risk of iterative loosening, but with a higher rate of dislocation, probably due to the lack of DM in many series. (4) What are the advantages and drawbacks of modular and custom metallic reconstructions? Modular reconstructions do not require 3D preoperative planning, but incur the risks of complications inherent to modularity. Custom implants can deal with more extensive defects, but require 5 to 8 weeks' production and are difficult to implant for the larger ones and/or when revision is limited to the acetabulum. (5) In what indications are these materials irreplaceable? Prior failure of allograft+cage in Paprosky type III defect with or without pelvic discontinuity shows the greatest benefit from metallic reconstruction, conditional on certain technical tricks. Only reconstructions using TM have more than 10 years' follow-up; other materials will need close monitoring. Failures in allograft with reinforcement cages occurred after about 10 years, and TM will need longer follow-up to prove its effectiveness. The high risk of dislocation should enable DM to be used, especially for small-diameter metallic reconstructions.

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.

Two-centre radiological survivorship of acetabular distraction technique for treatment of chronic pelvic discontinuity: mean five-year follow-up

Aims The aim of this study was to examine the results of the acetabular distraction technique in achieving implantation of a stable construct, obtaining biological fixation, and producing healing of chronic pelvic discontinuity at revision total hip arthroplasty. Patients and Methods We identified 32 patients treated between 2006 and 2013 who underwent acetabular revision for a chronic pelvic discontinuity using acetabular distraction, and who were radiographically evaluated at a mean of 62 months (25 to 160). Of these patients, 28 (87.5%) were female. The mean age at the time of revision was 67 years (44 to 86). The patients represented a continuous series drawn from two institutions that adhered to an identical operative technique. Results Of the 32 patients, one patient required a revision for aseptic loosening, two patients had evidence of radiographic loosening but were not revised, and three patients had migration of the acetabular component into a more stable configuration. Radiographically, 22 (69%) of the cohort demonstrated healing of the discontinuity. The Kaplan-Meier construct survivorship was 83.3% when using revision for aseptic acetabular loosening as an endpoint. At the time when one patient failed due to aseptic loosening (at 7.4 years), there were a total of seven patients with a follow-up of seven years or longer who were at risk of failure. Conclusion The acetabular distraction technique demonstrates encouraging radiographic outcomes, with healing of the discontinuity in over two-thirds of our series. This surgical technique permits biological fixation and intraoperative customization of the construct to be implanted based on the pattern of the bone loss identified following component removal. Cite this article: Bone Joint J 2018;100-B:909-14.

Treatment options for chronic pelvic discontinuity

Chronic pelvic discontinuity is a distinct and unique challenge seen during revision total hip arthroplasty (THA) in which the superior ilium is separated from the inferior ischiopubic segment through the acetabulum, rendering the anterior and posterior columns discontinuous. The operative management of acetabular bone loss in revision THA is one of the most difficult challenges today. Common treatment options include cage reconstruction with bulk acetabular allograft, custom triflange acetabular component, a cup-cage construct, jumbo acetabular cup with porous metal augments, or acetabular distraction with a porous tantalum shell with or without modular porous augments.

Three-Dimensional Models in Planning of Revision Hip Arthroplasty with Complex Acetabular Defects

BACKGROUND

Careful preoperative planning in revision cases with complex acetabular defects is crucial for optimal surgery outcome. However, in many cases, computed tomography (CT) scans cannot give a clear understanding of the pelvic destruction. Three-dimensional (3D) models-based on CT data can help surgeon in planning of complex acetabular reconstruction.

MATERIALS AND METHODS

We used 3D plaster pelvic models in 17 revision cases. There were 5 patients with Paprosky II C acetabular defects, 2 patients with Paprosky IIIA defects, and 10 patients with Paprosky IIIB defects (3 patients among them with pelvic discontinuity). We used 3D printer and digital 3D models based on CT scan data for 3D models printing. In 3 cases with Paprosky IIIB defects, we implanted custom-made acetabular components with the porous coating, also printed on the 3D printer.

RESULTS

In 14 cases, we used trabecular metal (TM) augments with TM cups. In 100% of cases, number and type of planned and used augments were same. In 9 (64.3%) cases, size of planned and used cups was same. In other cases, the difference was not >2 mm.

CONCLUSIONS

Use of 3D plaster models for the revision hip arthroplasty planning with complex acetabular defects has shown high accuracy in the clear understanding of acetabular bone deficiency.

[Treatment of acetabular defects with the trabecular metal revision system]

BACKGROUND

The results after acetabular component revision are very heterogeneous, irrespective of the use of established or new components. This could be due to a lack of treatment standards for new revision components. The Trabecular Metal™ (TM) revision system, through its modularity, allows for an individual intraoperative reconstruction of the acetabular defect with a single implant system. It was the aim of this study to investigate the results of acetabular revision with the TMT system taking into consideration the utilized components and the acetabular defect.

METHODS

A total of 200 consecutive isolated revisions of the acetabular component from 2010 until 2012 were retrospectively analyzed from our institutional database. Of the 200 cases, 114 revisions were performed with a combination of different TMT components (wedge and cup, cup and cage). Aseptic cup failure and revision for any reason were the defined endpoints of this study. The acetabular defects were graded according to the Paprosky classification.

RESULTS

The average patient age was 63.6 ± 14.8 years (range 32-85 years) and the average follow-up was 5.3 ± 0.7 years. The overall revision rate, independent of the utilized components, was 4.4% and the revision rate for aseptic failure of the acetabular component was 2.6%. The revision rate for aseptic loosening for Paprosky type I and II defects was 0% and Paprosky type III and IV defects was 12%.

CONCLUSIONS

The modular TMT system shows low revision rates. The modularity of the system allows for a safe and intraoperative adaptation to the individual acetabular defect without the need for extensive preoperative imaging or custom-made implants.

Reconstruction of AAOS type III and IV acetabular defects with the Ganz reinforcement ring: high failure in pelvic discontinuity

BACKGROUND

Large acetabular defects and pelvic discontinuity represent complex problems in revision total hip arthroplasty. This study aimed to investigate whether reconstruction with the Ganz reinforcement ring would provide durable function in large acetabular defects.

PATIENTS AND METHODS

46 hips (45 patients, 19 male, 26 female, mean age 68 years) with AAOS type III and IV defects undergoing acetabular revision with the Ganz reinforcement ring were evaluated at a mean follow-up of 74 months (24-161 months). Fourteen patients died during follow-up. All surviving patients were available for clinical assessment and radiographic studies. Radiographs were evaluated for bone healing and component loosening. A Cox-regression model was performed to identify factors influencing survival of the Ganz-ring.

RESULTS

In the group of AAOS III defects, 3 of 26 acetabular reconstructions failed, all due to aseptic loosening. In pelvic discontinuity (AAOS IV), 9 of 20 hips failed due to aseptic loosening (n = 4), deep infection (n = 3), and non-union of the pelvic ring (n = 2). With acetabular revision for any reason as an endpoint, the estimated Kaplan-Meier 5-year survival was 86% in type III defects and 57% in type IV defects, respectively. The presence of pelvic discontinuity was identified as the only independent predictive factor for failure of the Ganz ring acetabular reconstruction (AAOS III vs. IV, Hazard ratio: 0.217, 95%, Confidence interval: 0.054-0.880, p = 0.032).

CONCLUSION

The Ganz reinforcement ring remains a favorable implant for combined segmental and cavitary defects. However, defects with pelvic discontinuity demonstrate high failure rates. The indications should therefore be narrowed to acetabular defects not associated with pelvic discontinuity.

Pelvic Discontinuity Associated With Total Hip Arthroplasty: Evaluation and Management

Pelvic discontinuity is a challenging complication encountered during revision total hip arthroplasty. Pelvic discontinuity is defined as a separation of the ilium superiorly from the ischiopubic segment inferiorly and is typically a chronic condition in failed total hip arthroplasties in the setting of bone loss. After a history and a physical examination have been completed and infection has been ruled out, appropriate imaging must be obtained, including plain hip radiographs, oblique Judet radiographs, and often a CT scan. The main management options are a hemispheric acetabular component with posterior column plating, a cup-cage construct, pelvic distraction, and a custom triflange construct. The techniques have unique pros and cons, but the goals are to obtain stable and durable acetabular component fixation and a healed or unitized pelvis while minimizing complications.

AAHKS Symposium: State-of-the-Art Management of Tough and Unsolved Problems in Hip and Knee Arthroplasty

BACKGROUND

Incompletely solved problems in hip and knee arthroplasty present ongoing practice challenges.

METHODS

Content experts summarized treatment options and preferred treatment methods for 4 incompletely solved problems in hip and knee arthroplasty.

RESULTS

The problems chosen for discussion in this symposium included 2 soft tissue problems: chronic extensor mechanism deficiency after total knee arthroplasty and abductor deficiency after total hip arthroplasty (THA), recurrent infection after a 2-stage procedure for infected THA or total knee arthroplasties, and pelvic discontinuity after THA.

CONCLUSION

The approaches outlined may provide guidance on management of these different problems. For surgeons and others in the orthopedic community interested in innovation, these challenges also present ripe opportunities to improve the care of patients with unmet needs.

Custom 3D-printed acetabular implants in hip surgery--innovative breakthrough or expensive bespoke upgrade?

Custom 3D-printed triflange acetabular cages are a new option in the armamentarium of the revision hip surgeon. This review article defines this technology, its indications, surgical method, advantages, disadvantages, use, current published literature and future applications.

Pelvic discontinuity: modern techniques and outcomes for treating pelvic disassociation

Pelvic discontinuity is an uncommon condition that usually presents in the revision total hip arthroplasty population. However, its incidence will most likely increase due to the increasing number of primary and revision total hip arthroplasties (THA) done in recent years. Pelvic discontinuity (acetabular disassociation) is perhaps one of the more challenging cases for the hip arthroplasty surgeon to manage. Historically, the management of pelvic discontinuity has been wrought with many challenges. What follows is a review of the current techniques and outcomes for acetabular reconstruction in patients with acetabular disassociation including: porous metal components, internal fixation with acetabular reconstruction, acetabular distraction with jumbo cups, cup and cage construct, and the use of custom triflange.The complexity of pelvic discontinuity and with the myriad of options available to the hip arthroplasty surgeon to address this particular issue, preoperative planning becomes all the more essential.