Pelvic discontinuity is defined as a separation of the ilium superiorly from the ischiopubic segment inferiorly. In 2018, the main management options include the following: 1) hemispheric acetabular component with posterior column plating, 2) cup-cage construct, 3) pelvic distraction, and 4) custom triflange construct. A hemispheric acetabular component with posterior column plating is a good option for acute pelvic discontinuities. However, healing potential is dependent on host's biology and characteristic of the discontinuity. The plate should include 3 screws above and 3 screws below the discontinuity with compression in between. In addition, the hemispherical acetabular component should have at least 50% host bone contact with 3–4 screws superior and 2–3 screws inferior to the discontinuity. On the other hand, a cup-cage construct can be used in any pelvic discontinuity. This includes a highly porous acetabular component placed on remaining host bone. Occasionally, highly porous metal augments are used to fill the remaining bone defects. A supplemental cage is placed over the acetabular component, spanning the discontinuity from the ilium to the ischium. A polyethylene liner is then cemented into place with antibiotic-loaded bone cement. Rarely, pelvic distraction may be needed. With this technique, pelvic stability is obtained via distraction of the discontinuity by elastic recoil of the pelvis and by fixing the superior hemipelvis and inferior hemipelvis to a highly porous metal cup or augment with screws, thereby unitizing the superior and inferior aspects of the pelvis. In essence, the cup acts as a segmental replacement of the acetabulum, with healing occurring to the cup or augment, resulting in a unitised hemipelvis. Frequently, the discontinuity itself does not achieve bony healing. Finally, custom triflange constructs are being utilised with increasing frequency. Triflange cups are custom-designed, porous and/or hydroxyapatite coated, titanium acetabular components with iliac, ischial, and pubic flanges. Rigid fixation promotes healing of the discontinuity and biologic fixation of the implant. It requires a CT scan, dedicated preoperative design, and fabrication costs

Stabilisation of a pelvic discontinuity with a posterior column plate with or without an associated acetabular cage sometimes results in persistent micromotion across the discontinuity with late fatigue failure and component loosening. Acetabular distraction offers an alternative technique for reconstruction in cases of severe bone loss with an associated pelvic discontinuity. We describe the technique of acetabular distraction with porous tantalum components and evaluate its survival, function and complication rate in patients undergoing revision surgery for chronic pelvic discontinuity. Between 2002 and 2006, we treated 28 patients with a chronic pelvic discontinuity acetabular reconstruction using acetabular distraction. A porous tantalum elliptical acetabular component was used alone or with an associated modular porous tantalum augment in all patients. Three patients died and five patients were lost to follow-up before two years. The remaining twenty patients were followed semiannually for a minimum of two years (average, 4.5 years; range, 2–7 years) with clinical pain and walking scores as well as radiographic evaluation for loosening, migration or failure. In the remaining twenty patients available for follow-up, one patient did require re-revision for aseptic loosening. Fifteen patients remained radiographically stable at last follow-up. Four patients had early migration of their acetabular component but thereafter remained radiographically stable and clinically asymptomatic. The average improvement using the modified Merle d'Aubigne – Postel pain and ambulation score was 6.6 (range, 3.3–9.6). There were no postoperative dislocations; however, we did encounter one infection, one vascular injury and one bowel injury. In this series, the use of acetabular distraction with porous tantalum components provides a biologic alternative to cage constructs with more predictable clinical results (average follow-up 4.5 years) for reconstruction of severe acetabular defects with associated pelvic discontinuity

Stabilisation of a chronic pelvic discontinuity with a posterior column plate with or without an associated acetabular cage sometimes results in persistent micromotion across the discontinuity with late fatigue failure and component loosening. We believe that these chronic discontinuities are really chronic fracture non-unions incapable of healing. Acetabular distraction offers an alternative technique for reconstruction in cases of severe bone loss with an associated pelvic discontinuity. We describe the technique of acetabular distraction with porous tantalum components and evaluate its survival, function and complication rate in patients undergoing revision surgery for chronic pelvic discontinuity. Between 2002 and 2006, we treated 28 patients with a chronic pelvic discontinuity acetabular reconstruction using acetabular distraction. A porous tantalum elliptical acetabular component was used alone or with an associated modular porous tantalum augment in all patients. Three patients died and five patients were lost to follow up before two years. The remaining twenty patients were followed semiannually for a minimum of two years (average, 5.5 years; range, 2–9 years) with clinical pain and walking scores as well as radiographic evaluation for loosening, migration or failure. In the remaining twenty patients available for follow up, one patient did require re-revision for aseptic loosening. Fifteen patients remained radiographically stable at last follow up. Four patients had early migration of their acetabular component but thereafter remained radiographically stable and clinically asymptomatic. The average improvement using the modified Merle d'Aubigne – Postel pain and ambulation score was 6.6 (range, 3.3–9.6). There were no post-operative dislocations; however, we did encounter one infection, one vascular injury and one bowel injury. In this series, the use of acetabular distraction with porous tantalum components provides a biologic alternative to cage constructs with more predictable clinical results (average follow up 5.5 years) for reconstruction of severe acetabular defects with associated pelvic discontinuity

In our center the cup cage reconstruction is our most common technique where a cage is used, especially if there is a pelvic discontinuity. Cup Cage Construct – in this construct there must be enough bleeding host bone to stabilise the ultraporous cup which functions like a structural allograft supporting and eventually taking the stress off the cage. This construct is ideal for pelvic discontinuity with the ultraporous cup, i.e., bridging and to some degree distracting the discontinuity. If, however, the ultra-porous cup cannot be stabilised against some bleeding host bone, then a conventional stand-alone cage must be used. Acetabular bone loss and presence of pelvic discontinuity were assessed according to the Gross classification. Sixty-seven cup cage procedures with an average follow-up of 74 months (range, 24–135 months; SD, 34.3 months) were identified; 26 of 67 (39%) were Gross Type IV and 41 of 67 (61%) were Gross Type V (pelvic discontinuity). Failure was defined as revision surgery for any cause, including infection. The 5-year Kaplan-Meier survival rate with revision for any cause representing failure was 93% (95% confidence interval, 83.1–97.4), and the 10-year survival rate was 85% (95% CI, 67.2–93.8). The Merle d'Aubigné-Postel score improved significantly from a mean of 6 pre-operatively to 13 post-operatively (p < 0.001). Four cup-cage constructs had non-progressive radiological migration of the ischial flange and they remain stable

Pelvic discontinuity with associated bone loss is a complex challenge acetabular revision surgery. Reconstruction by the use of ilio-ischial cages combined with trabecular metal acetabular components and morsellised bone (the component-cage technique) is a relatively new method of treatment. The trabecular cup provides a good environment for bone graft remodeling and eventual bone or fibrous ingrowth. The cage protects the trabecular metal cup until stabilisation occurs. The cage not only protects the cup but places the articulating center at the correct level. We reviewed a consecutive series of 32 cases of acetabular revision reconstructions with pelvic discontinuity who had been treated by the cup-cage technique. The mean follow-up was 38 months (24.0 to 68.0). Failure was defined as a migration of a component of >5mm. In 29 hips there was no clinical or radiological evidence of loosening at the last follow-up. The Harris hip scores improved significantly from 44.6 (sd 10.4) to 78.7 (sd 10.4) points (p<0.001). In three hips (11.5%) the construct migrated at one year after surgery. The complications included two cases of dislocations, one of infection and one of partial palsy of the peroneal nerve. Our findings indicated that the treatment of pelvic discontinuity by the component-cage construct is a reliable option

Pelvic discontinuity remains one of the most difficult reconstructive challenges during acetabular revision. Bony defects are extremely variable and remaining bone quality may be extremely poor. Careful pre-operative imaging with plain radiographs, oblique views, and CT scanning is recommended to improve understanding of the remaining bone stock. It is wise to have several options available intra-operatively including metal augments, jumbo cups, and cages. Various treatment options have been used with variable success. The principles of management include restoration of acetabular stability by “connecting” the ilium to the ischium, and by (hopefully) allowing some bony ingrowth into a porous surface to allow longer-term construct stability. Posterior column plates can be useful to stabilise the pelvis, and can supplement a trabecular metal uncemented acetabular component. Screws into the dome and into the ischium are used to span the discontinuity. More severe defects may require so-called “cup-cage” constructs or trabecular metal augmentation distraction techniques. The most severe defects typically necessitate custom triflange components. Triflange constructs allow broad based contact with remaining bone stock, and can span surprisingly large defects. Recent cost analyses have shown that custom triflange constructs are comparable to cup-cage-augment reconstructions. The results of these various solutions to manage pelvic discontinuity is extremely variable, however, it is fair to conclude that constructs that allow some bony ingrowth have demonstrated improved survivorship when compared to historical treatments such as bulk allografts protected by cages. The author prefers a posterior column plate and a trabecular metal cup for simple discontinuities, a cup-cage for larger defects, and a custom triflange for the most severe defects. Pre-operative imaging is critical to guide this decision-making, and careful attention to detail is important to obtain a stable, durable construct

Although the introduction of ultraporous metals in the forms of acetabular components and augments has substantially improved the orthopaedic surgeon's ability to reconstruct severely compromised acetabuli, there remain some revision THAs that are beyond the scope of cups, augments, and cages. In situations involving catastrophic bone loss, allograft-prosthetic composites or custom acetabular components may be considered. Custom components offer the potential advantages of immediate, rigid fixation with a superior fit individualised to each patient. These custom triflange components require a pre-operative CT scan with 3-D reconstruction using rapid prototyping technology. The surgeon can fine-tune exact component positioning, determine location and length of screws, modify the fixation surface with, for example, the addition of hydroxyapatite, and dictate which screws will be locked to enhance fixation. The general indications for using custom triflange components include: (1) failed prior salvage reconstruction with cage or porous metal construct augments, (2) large contained defects with possible discontinuity, (3) known pelvic discontinuity, and (4) complex multiply surgically treated hips with insufficient bone stock to reconstruct using other means. The general indications for using custom triflange components include: (1) failed prior salvage reconstruction with cage or porous metal construct augments, (2) large contained defects with possible discontinuity, (3) known pelvic discontinuity, and (4) complex multiply surgically treated hips with insufficient bone stock to reconstruct using other means. We previously reported on our center's experience with 23 patients (24 hips) treated with custom triflange components with minimum 2-year follow-up. This method of reconstruction was used in a cohort of patients with Paprosky Type 3B acetabular defects, which represented 3% (30 of 955) of the acetabular revisions we performed during the study period of 2003 to 2012. At a mean follow-up of 4.8 years (range, 2.3–9 years) there were 4 subsequent surgical interventions: 2 failures secondary to sepsis, and 1 stem revision and 1 open reduction internal fixation for periprosthetic femoral fracture. There were two minor complications managed non-operatively, but all of the components were noted to be well-fixed with no obvious migration or loosening observed on the most recent radiographs. Harris Hip Scores improved from a mean of 42 (SD ±16) before surgery to 65 (SD ±18) at latest follow-up (p<0.001). More recently, we participated in a multi-center study of 95 patients treated with reconstruction using custom triflange components w a mean follow-up of 3.5 years. Pelvic defects included Paprosky Type 2C, 3A, 3B and pelvic discontinuity. Concomitant femoral revision was performed in 21 hips. Implants used a mean of 12 screws with 3 locking screws. Twenty of 95 patients (21%) experienced at least one complication, including 6% dislocation, 6% infection, and 2% femoral-related issues. Implants were ultimately removed in 11% of hips. One hip was revised for possible component loosening. Survivorship with aseptic loosening as the endpoint was 99%. Custom acetabular triflange components represent yet another tool in the reconstructive surgeon's armamentarium. These devices can be helpful in situations of catastrophic bone loss, achieving reliable fixation. Clinical results are inferior to both primary THA and more routine revision THA. Patients and surgeons should be aware of the increased complications associated with these complex hip revisions

Revision surgery for pelvic discontinuity in the presence of bone loss is challenging. The cup-cage reconstruction option has become popular for the management of pelvic discontinuity in the recent years. The aim of this study was to review the clinical, radiological and patient reported outcomes with the use of cup cage construct for pelvic discontinuity at our institution. Twenty-seven patients (27 cup-cage reconstructions) were identified at median 6-year (minimum 2 year, maximum 10 years) follow up. Eight were female patients. The median age was 77 years [mean 72, range 37–90, SD 13.6]. There were 5 deaths and 2 were lost to follow up. Two patients were converted to excision arthroplasty; one for infection and one for failure of the construct. A further 3 patients required revision for instability but the cup cage construct was not revised (2 revisions of cemented cups to a constrained cup and one revision of proximal modular component of the femoral prosthesis). Revision of the cup cage construct was not necessary in any of these cases. We noted excellent pain relief (mean WOMAC pain 85.6) and good functional outcome (mean WOMAC function 78.2, mean UCLA 5, mean OHS 78.6). Patient satisfaction with regards pain relief; function and return to activities were noted to be excellent. Radiological changes were noted in further 4 patients (cup migration in one case; fracture of ischial spike in one case and breakage of the cage screws in 2 patients). No migration of the construct was noted in any of the cases. In conclusion, the cup cage construct is an excellent method of dealing with complex pelvic discontinuity. Our study suggests a low failure rate; high patient satisfaction and pain relief and moderate functional outcome at median 6 year follow up

Acetabular distraction for the treatment of chronic pelvic discontinuity was first described by Sporer and Paprosky. The authors advocate the posterolateral approach for exposure of the posterior ilium and posterior column, The patient is secured in the lateral decubitus position. Following a systematic approach to surgical exposure, acetabular component removal should be performed with “cup out” osteotomes resulting in minimal iatrogenic bone loss. Following component removal and confirmation of a chronic discontinuity determine the integrity of the remaining AS and PI columns. If porous metal augments are needed for primary stabilization, the augments are placed prior to cup insertion for reconstruction of the AS and/or PI column. Next, Kirschner (K) wires (size 2.4) are placed in the remaining AS and PI bone so that the distractor can be secured in an extra-acetabular position. The distractor is placed over the K-wires allowing for lateral or peripheral acetabular distraction and resultant medial or central compression at the discontinuity. With the distractor in an extra-acetabular position, hemispherical reamers are used until an interference fit is achieved between the native or augmented AS and PI columns. The acetabulum should be reamed on reverse to avoid excessive removal of host bone. When the proper acetabular component size has been reached, the reamer will disengage from the reamer handle and the reamer can be used as a surrogate acetabular shell; when the acetabulum is maximally distracted, the entire construct will move as a unit. Crushed cancellous allograft is used to bone graft the discontinuity and reamed on reverse. A revision tantalum cup is inserted with continual distraction using the distractor. Cement is applied to the augment surface prior to cup insertion in order to utilise the construct. Following cup insertion, the distractor and K-wires are removed. Adjuvant screw fixation is performed, with a minimum of 4 screws, and placing at least one of the screws inferiorly for fixation in the superior public ramus or ischium to prevent abduction failure of the construct. In the setting of severely osteoporotic bone and inadequate screw fixation, an augment placed posterosuperiorly can be used for supplemental fixation. This augment is also unitised to the cup with cement at the same time as the liner is cemented into the cup. Bone wax is placed over the exposed tantalum surface of the posterosuperior augment to minimise soft-tissue ingrowth into the augment

The custom triflange acetabular component has been advocated for severe acetabular defects and pelvic discontinuity, cases in which a porous-coated hemisphere will not work. These are AAOS type III or IV defects, or alternatively classified as Paprosky 3B. Many have a pelvic discontinuity. A preoperative CT of the pelvis is sent to the manufacturer who generates a one to one scale 3D model of the hemipelvis. If the visualised defect cannot be treated with traditional methods then a triflanged component is created. Initial rigid fixation is obtained with screw fixation to the ilium and ischium. Subsequent bone ingrowth can provide long term fixation. The goal is to span the acetabular defect and obtain fixation to ilium and ischium with a third flange which rests on the pubis. Christie first reported on 67 hips (half with a discontinuity) with a mean follow-up of 53 months. No components were removed. There was an 8% reoperation for dislocation, 6% partial sciatic nerve palsy. Dennis reported 26 hips with a mean 54 month follow-up. Eighty-eight percent were considered successful. Taunton reported 57 cases with a pelvic discontinuity treated with a triflange at mean follow-up of 65 months. Eighty-one percent had a stable component and a healed pelvic discontinuity. The primary disadvantage of the technique is the preoperative time required to manufacture the device – typically 4–8 weeks

The custom triflange acetabular component has been advocated for severe acetabular defects and pelvic discontinuity, cases in which a porous-coated hemisphere will not work. These are AAOS type III or IV defects, or alternatively classified as Paprosky 3B. Many have a pelvic discontinuity. A pre-operative CT of the pelvis is sent to the manufacturer who generates a one-to-one scale 3D model of the hemipelvis. The surgeon can review either a pdf file or an actual model. If the visualised defect cannot be treated with traditional methods then a triflanged component is created. The components have backside porous and hydroxyapatite coating. Initial rigid fixation is obtained with screw fixation to the ilium and ischium. Subsequent bone ingrowth can provide long term fixation. The goal is to span the acetabular defect and obtain fixation to the ilium and ischium with a third arm which rests on the pubis. Christie first reported on 67 hips (half with a discontinuity) with a mean follow-up of 53 months. No components were removed. There was an 8% reoperation for dislocation, 6% partial sciatic nerve palsy. 46% walked without support. Dennis reported 26 hips with a mean 54 month follow-up. Eighty-eight percent were considered successful. One implant was removed and left with a resection arthroplasty and 2 others had loose components but refused reoperation. Loosening of the ischial screws was a sign of failure in the three cases. Taunton reported 57 cases with a pelvic discontinuity treated with a triflange at mean follow-up of 65 months. Eighty-one percent had a stable component and a healed pelvic discontinuity. These authors also compared a custom triflange to a trabecular metal cup-cage construct finding similar implant costs of $12,500 and $11,250, respectively. All advocates of custom triflange acetabular components believe the results are similar or superior to other options in these very challenging cases at early follow-up. The primary disadvantage of the technique is the pre-operative time required to manufacture the device – typically 4–8 weeks

The custom triflange acetabular component has been advocated for severe acetabular defects and pelvic discontinuity, cases in which a porous-coated hemisphere will not work. These are AAOS type III or IV defects, or alternatively classified as Paprosky 3B. Many have a pelvic discontinuity. A preoperative CT of the pelvis is sent to the manufacturer who generates a one-to-one scale 3D model of the hemipelvis. The surgeon can review either a pdf file or an actual model. If the visualised defect cannot be treated with traditional methods then a triflanged component is created. The components have backside porous and hydroxyapatite coating. Initial rigid fixation is obtained with screw fixation to the ilium and ischium. Subsequent bone ingrowth can provide long term fixation. The goal is to span the acetabular defect and obtain fixation to ilium and ischium with a third arm which rests on the pubis. Christie first reported on 67 hips (half with a discontinuity) with a mean follow-up of 53 months. No components were removed. There was an 8% reoperation for dislocation, 6% partial sciatic nerve palsy. 46% walked without support. Dennis reported 26 hips with a mean 54 month follow-up. 88% were considered successful. One implant was removed and left with a resection arthroplasty and 2 others had loose components but refused reoperation. Loosening of the ischial screws was a sign of failure in the three cases. Taunton reported 57 cases with a pelvic discontinuity treated with a triflange at mean follow-up of 65 months. 81% has a stable component and a healed pelvic discontinuity. These authors also compared a custom triflange to a trabecular metal cup-cage construct finding similar implant costs of $12,500 and $11,250, respectively. All advocates of custom triflange acetabular components believe the results are similar or superior to other options in these very challenging cases at early follow-up. The primary disadvantage of the technique is the preoperative time required to manufacture the device – typically 4–8 weeks

Acetabular cages are necessary when an uncemented or cemented cup cannot be stabilised at the correct anatomic level. Impaction grafting with mesh for containment of bone graft is an alternative for some cases in centers that specialise in this technique. At our center we use three types of cage constructs –. (A). Conventional cage ± structural or morselised bone grafting. This construct is used where there is no significant bleeding host bone. This construct is susceptible to cage fatigue and fracture, This reconstruction is used in young patients where restoration of bone stock is important. (B). Conventional cage in combination with a porous augment where contact with bleeding host bone can be with the ilium and then by the use of cement that construct can be unified. The augment provides contact with bleeding host bone and if and when ingrowth occurs, the stress is taken off the cage. (C). Cup-Cage Construct – in this construct there must be enough bleeding host bone to stabilise the ultra-porous cup which functions like a structural allograft supporting and eventually taking the stress off the cage. This construct is ideal for pelvic discontinuity with the ultra-porous cup, i.e., bridging and to some degree distracting the discontinuity. If, however, the ultra-porous cup cannot be stabilised against some bleeding host bone, then a conventional stand-alone cage must be used. In our center the cup-cage reconstruction is our most common technique where a cage is used, especially if there is a pelvic discontinuity. Acetabular bone loss and presence of pelvic discontinuity were assessed according to the Gross classification. Sixty-seven cup-cage procedures with an average follow-up of 74 months (range, 24–135 months; SD, 34.3) months were identified; 26 of 67 (39%) were Gross Type IV and 41 of 67 (61%) were Gross Type V (pelvic discontinuity). Failure was defined as revision surgery for any cause, including infection. The 5-year Kaplan-Meier survival rate with revision for any cause representing failure was 93% (95% confidence interval, 83.1–97.4), and the 10-year survival rate was 85% (95% CI, 67.2–93.8). The Merle d'Aubigné-Postel score improved significantly from a mean of 6 pre-operatively to 13 post-operatively (p < 0.001). Four cup-cage constructs had non-progressive radiological migration of the ischial flange and they remain stable

Acetabular cages are necessary when an uncemented or cemented cup cannot be stabilised at the correct anatomic level. Impaction grafting with mesh for containment of bone graft is an alternative for some cases in centers that specialise in this technique. At our center we use three types of cage constructs –. (A) Conventional cage ± structural or morselised bone grafting. This construct is used where there is no significant bleeding host bone. This construct is susceptible to cage fatigue and fracture. This reconstruction is used in young patients where restoration of bone stock is important. (B) Conventional cage in combination with a porous augment where contact with bleeding host bone can be with the ilium and then by the use of cement that construct can be unified. The augment provides contact with bleeding host bone and if and when ingrowth occurs, the stress is taken off the cage. (C) Cup Cage Construct – in this construct there must be enough bleeding host bone to stabilise the ultra-porous cup which functions like a structural allograft supporting and eventually taking the stress off the cage. This construct is ideal for pelvic discontinuity with the ultra-porous cup, i.e., bridging and to some degree distracting the discontinuity. If, however, the ultra-porous cup cannot be stabilised against some bleeding host bone, then a conventional stand-alone cage must be used. In our center the cup cage reconstruction is our most common technique where a cage is used, especially if there is a pelvic discontinuity. Acetabular bone loss and presence of pelvic discontinuity were assessed according to the Gross classification. Sixty-seven cup-cage procedures with an average follow-up of 74 months (range, 24–135 months; SD, 34.3) months were identified; 26 of 67 (39%) were Gross Type IV and 41 of 67 (61%) were Gross Type V (pelvic discontinuity). Failure was defined as revision surgery for any cause, including infection. The 5-year Kaplan-Meier survival rate with revision for any cause representing failure was 93% (95% confidence interval, 83.1–97.4), and the 10-year survival rate was 85% (95% CI, 67.2–93.8). The Merle d'Aubigné-Postel score improved significantly from a mean of 6 pre-operatively to 13 post-operatively (p < 0.001). Four cup-cage constructs had non-progressive radiological migration of the ischial flange and they remain stable

Although the introduction of ultraporous metals in the forms of acetabular components and augments has substantially improved the orthopaedic surgeon's ability to reconstruct severely compromised acetabuli, there remain some revision THAs that are beyond the scope of cups, augments, and cages. In situations involving catastrophic bone loss, allograft-prosthetic composites or custom acetabular components may be considered. Custom components offer the potential advantages of immediate, rigid fixation with a superior fit individualised to each patient. These custom triflange components require a pre-operative CT scan with three-dimensional (3-D) reconstruction using rapid prototyping technology, which has evolved substantially during the past decade. The surgeon can fine-tune exact component positioning, determine location and length of screws, modify the fixation surface with, for example, the addition of hydroxyapatite, and dictate which screws will be locked to enhance fixation. The general indications for using custom triflange components include: (1) failed prior salvage reconstruction with cage or porous metal construct augments, (2) large contained defects with possible discontinuity, (3) known pelvic discontinuity, and (4) complex multiply surgically treated hips with insufficient bone stock to reconstruct using other means. The general indications for using custom triflange components include: (1) failed prior salvage reconstruction with cage or porous metal construct augments, (2) large contained defects with possible discontinuity, (3) known pelvic discontinuity, and (4) complex multiply surgically treated hips with insufficient bone stock to reconstruct using other means. We previously reported on our center's experience with 23 patients (24 hips) treated with custom triflange components with minimum 2-year follow-up. This method of reconstruction was used in a cohort of patients with Paprosky Type 3B acetabular defects, which represented 3% (30 of 955) of the acetabular revisions we performed during the study period of 2003 to 2012. At a mean follow-up of 4.8 years (range, 2.3–9 years) there were 4 subsequent surgical interventions: 2 failures secondary to sepsis, and 1 stem revision and 1 open reduction internal fixation for periprosthetic femoral fracture. There were 2 minor complications managed nonoperatively, but all of the components were noted to be well-fixed with no obvious migration or loosening observed on the most recent radiographs. Harris hip scores improved from a mean of 42 (SD ± 16) before surgery to 65 (SD ± 18) at latest follow-up (p<0.001). More recently, we participated in a multi-center study of 95 patients treated with reconstruction using custom triflange components who had a mean follow-up of 3.5 years. Pelvic defects included Paprosky Type 2C, 3A, 3B and pelvic discontinuity. Concomitant femoral revision was performed in 21 hips. Implants used a mean of 12 screws with 3 locking screws. Twenty of 95 patients (21%) experienced at least one complication, including 6% dislocation, 6% infection, and 2% femoral-related issues. Implants were ultimately removed in 11% of hips. One hip was revised for possible component loosening. Survivorship with aseptic loosening as the endpoint was 99%,. Custom acetabular triflange components represent yet another tool in the reconstructive surgeon's armamentarium. These devices can be helpful in situations of catastrophic bone loss, achieving reliable fixation. Clinical results are inferior to both primary THA and more routine revision THA. Patients and surgeons should be aware of the increased complications associated with these complex hip revisions

The treatment of extensive bone loss and massive acetabular defects is a challenging procedure, especially in cases with concomitant pelvic discontinuity (PD). Pelvic discontinuity describes the separation of the ilium proximally from the ischio-pubic region distally. The appropriate treatment strategy is to restore a stable continuity between the ischium and the ilium to reconstruct the anatomical hip center. Several treatment options such as antiprotrusio cages, metal augments, reconstruction cages with screw fixation, structural allograft with plating, jumbo cups, oblong cups and custom-made triflange acetabular components have been described as possible treatment options. Cage and/or ring constructs or acetabular allograft are commonly used techniques with unsatisfactory results and high failure rates. More favorable results have been presented with custom triflange acetabular components (CTAC), although the results are still unsatisfactory. Three-dimensional printing technology (3DP) has already become part of the surgical practice. In this context, preliminary clinical and radiological results using a 3D-printed custom acetabular component in the management of extensive acetabular defects are presented. The overall complication rate was 33.3 %. In one out of 15 patients (6.6 %), implant-associated complication occurred revealing an overall implant-associated survival rate of 93.3%. The 3D-printed custom acetabular component suggests a promising future, although the manufacturing process has high costs and the complication rate is still high

Although the introduction of ultraporous metals in the forms of acetabular components and augments has substantially improved the orthopaedic surgeon's ability to reconstruct severely compromised acetabuli, there remain some revision THAs that are beyond the scope of cups, augments, and cages. In situations involving catastrophic bone loss, allograft-prosthetic composites or custom acetabular components may be considered. Custom components offer the potential advantages of immediate, rigid fixation with a superior fit individualised to each patient. These custom triflange components require a preoperative CT scan with three-dimensional (3-D) reconstruction using rapid prototyping technology, which has evolved substantially during the past decade. The surgeon can fine-tune exact component positioning, determine location and length of screws, modify the fixation surface with, for example, the addition of hydroxyapatite, and dictate which screws will be locked to enhance fixation. The general indications for using custom triflange components include: (1) failed prior salvage reconstruction with cage or porous metal construct augments, (2) large contained defects with possible discontinuity, (3) known pelvic discontinuity, and (4) complex multiply surgically treated hips with insufficient bone stock to reconstruct using other means. We previously reported on our center's experience with 23 patients (24 hips) treated with custom triflange components with minimum 2-year follow-up. This method of reconstruction was used in a cohort of patients with Paprosky Type 3B acetabular defects, which represented 3% (30 of 955) of the acetabular revisions we performed during the study period of 2003 to 2012. At a mean follow-up of 4.8 years (range, 2.3 – 9 years) there were four subsequent surgical interventions: two failures secondary to sepsis, and one stem revision and one open reduction internal fixation for periprosthetic femoral fracture. There were two minor complications managed nonoperatively, but all of the components were noted to be well-fixed with no obvious migration or loosening observed on the most recent radiographs. Harris hip scores improved from a mean of 42 (SD ±16) before surgery to 65 (SD ±18) at latest follow-up (p < 0.001). More recently, we participated in a multi-center study of 95 patients treated with reconstruction using custom triflange components who had a mean follow-up of 3.5 years. Pelvic defects included Paprosky Type 2C, 3A, 3B and pelvic discontinuity. Concomitant femoral revision was performed in 21 hips. Implants used a mean of 12 screws with 3 locking screws. Twenty of 95 patients (21%) experienced at least one complication, including 6% dislocation, 6% infection, and 2% femoral-related issues. Implants were ultimately removed in 11% of hips. One hip was revised for possible component loosening. Survivorship with aseptic loosening as the endpoint was 99%. Custom acetabular triflange components represent yet another tool in the reconstructive surgeon's armamentarium. These devices can be helpful in situations of catastrophic bone loss, achieving reliable fixation. Clinical results are inferior to both primary THA and more routine revision THA. Patients and surgeons should be aware of the increased complications associated with these complex hip revisions

Impaction grafting is an excellent option for acetabular revision. It is technique specific and very popular in England and the Netherlands and to some degree in other European centers. The long term published results are excellent. It is, however, technique dependent and the best results are for contained cavitary defects. If the defect is segmental and can be contained by a single mesh and impaction grafting, the results are still quite good. If, however, there is a larger segmental defect of greater than 50% of the acetabulum or a pelvic discontinuity, other options should be considered. Segmental defects of 25–50% can be managed by minor column (shelf) or figure of 7 structural allografts with good long term results. Porous metal augments are now a good option with promising early to mid-term results. Segmental defects of greater than 50% require a structural graft or porous augment usually protected by a cage. If there is an associated pelvic discontinuity then a cup cage is a better solution. An important question is does impaction grafting facilitate rerevision surgery? There is no evidence to support this but some histological studies of impacted allograft would suggest that it may. On the other hand there are papers that show that structural allografts do restore bone stock for further revision surgery. Also the results of impaction grafting are best in the hands of surgeons comfortable with using cement on the acetabular side, and one of the reasons why this technique is not as popular in North America

THA after acetabular fracture presents unique technical challenges. These challenges include bone deformity, bone deficiency, sclerotic or dysvascular bone, non-united bony fragments, pelvic discontinuity, retained hardware, heterotopic ossification, previous incisions, and concerns regarding the sciatic nerve. Despite these challenges, with current treatment methods, a high degree of success can be achieved with modern technology. Preoperative evaluation for infection - In previously operated acetabular fractures, infection is always a concern. Screening C-reactive protein and sedimentation rate may be performed. If a concern regarding infection is present, the hip may be aspirated; Incisions - In most cases, a previous incision may be utilised. If necessary, an incision may be extended or a new limb can be created and attention should be paid to maintaining optimal skin bridges. In cases with a high degree of concern about infection, a staged procedure may be considered. However, in most cases, hardware removal can be done selectively at the time of THA surgery. Hardware that does not compromise placement of the THA may be left in place. Sometimes hardware can be cut off within the acetabulum to minimise exposure needs. The reconstructive goal is to place the hip center as close as possible to normal hip center but also to gain good support of the socket on host bone. In most cases, both goals can be met. When necessary, some compromise in hip center of rotation may be considered to optimise implant stability on host bone. The principles of revision surgery are followed using uncemented acetabular components fixed with augmentation screws. Most bone deficiencies may be managed with methods similar to revision hip surgery. However, in the acetabular fracture patient, usually the host femoral head is available and this can be used as bone graft, either in particulate or bulk form. Most cavitary deficiencies can be dealt with particulate bone graft. Some superolateral bone deficiencies from posterior wall fractures may be considered for bone grafting or augmentation techniques. Nonunited fractures are not uncommon in these circumstances. Small wall nonunions may be managed as noted above for bone deficiency. If pelvic discontinuity is present, it is usually best treated by following the rules established for treatment of pelvic discontinuity with pelvic plating. Pelvic plating provides a reasonable likelihood of bone healing in these circumstances when combined with bone grafting techniques. Heterotopic ossification is common in previously operated acetabular fractures. Removal of heterotopic bone at the time of surgery to gain hip motion is routine. Postoperative measures to reduce the likelihood of bone formation (that is either shielded radiation or use of a nonsteroid anti-inflammatory agent) may be strongly considered. The sciatic nerve is at risk during these procedures. In many cases, avoiding the nerve and the region of the nerve is a reasonable approach. When a lot of work must be done on the posterior column, the surgeon needs to know exactly where the nerve is and in such cases the nerve may be exposed distally beneath the gluteus maximus tendon and followed proximally with careful and judicious dissection. Results of total hip arthroplasty after acetabular fracture have varied in the past. More recent series have shown a high rate of acetabular fixation associated with uncemented hemispherical implants. Acetabular fracture patients are disproportionately young and active with unilateral hip disease and, therefore, bearing surfaces should be chosen accordingly

Acetabular cages are necessary when an uncemented or cemented cup cannot be stabilised at the correct anatomic level. Impaction grafting with mesh for containment of bone graft is an alternative for some cases in centers that specialise in this technique. At our center we use three types of cage constructs:. (A). Conventional cage ± structural or morselised bone grafting. This construct is used where there is no significant bleeding host bone. This construct is susceptible to cage fatigue and fracture. This reconstruction is used in young patients where restoration of bone stock is important. (B). Conventional cage in combination with a porous augment where contact with bleeding host bone can be with the ilium and then by the use of cement that construct can be unified. The augment provides contact with bleeding host bone and if and when ingrowth occurs, the stress is taken off the cage. (C). Cup Cage Construct – in this construct there must be enough bleeding host bone to stabilise the ultra-porous cup which functions like a structural allograft supporting and eventually taking the stress off the cage. This construct is ideal for pelvic discontinuity with the ultra-porous cup, i.e., bridging and to some degree distracting the discontinuity. If, however, the ultra-porous cup cannot be stabilised against some bleeding host bone, then a conventional stand-alone cage must be used. In our center the cup cage reconstruction is our most common technique where a cage is used, especially if there is a pelvic discontinuity