Fifty-five patients undergoing isolated acetabular revisions in fifty-seven hips were available for review. In thirty-three of fifty-seven hips there was no significant acetabular deficiency; of the remaining twenty-four hips twenty underwent allograft reconstruction and four autogenous bone grafting. Mean follow-up was four years with a range of three to seven years; there have been no femoral loosening, and three further surgical procedures for hip instability. All acetabular components at last review were soundly fixed with the exception of one patient who underwent excision arthroplasty at twelve months for deep infection. The purpose of this study was to review the functional outcome and the fate of the femoral stem and revised acetabular component following isolated ace-tabular revision. Findings of the current study demonstrate that isolated acetabular revision does not compromise the final functional nor radiographic outcome in acetabular revision in appropriately selected patients; the fate of the femoral component is not adversely influenced by this procedure. There is no need to remove the femoral component at the time of acetabular revision if the femoral component is well fixed and stable by pre- and intra-operative assessment. Prospectively entered data on fifty-seven hips (fifty-five patients) who have undergone isolated acetabular revision without femoral revision was available for review. All patients were assessed pre-operatively and post-operatively on an annual basis by means of physical examination, x-ray, SF-36 and WOMAC questionnaires. In thirty-three of fifty-seven hips there was no significant acetabular deficiency; of the remaining twenty-four hips, one had a segmental defect, thirteen had a cavitary defect and ten had a combined segmental and cavitary defect. Osteolysis existed in the proximal femur of two hips. Bone grafting in twenty-four hips consisted of morselized allograft in nine; combined structural and morselized allograft used in eleven and autogenous bone used in four acetabular defects. Autogenous bone grafting was done in two femoral osteolytic lesions. Mean follow-up was four years with a range of three to seven years. The mean duration of arthroplasty prior to revision was fourteen years (range four to twenty-three years). There were no nerve palsies, vascular injuries or intra-operative fractures in this patient group. All ace-tabular components at latest review were soundly fixed with the exception of one patient who underwent excision arthroplasty at twelve months for deep infection. Twenty-one of the twenty-four hips with bone grafting demonstrated positive radiographic signs of incorporation; the remaining threehips have a stable interface but no evidence of bone ingrowth. Three of the fifty-seven hips presented with hip dislocations after revision arthroplasty; two were managed by closed reduction; the third by open reduction and soft tissue repair

A common finding in acetabular revisions is loss of medial bone stock. Using a standard cementless hemispherical component, alternatives for reconstruction include medialisation of the cup, medial particulate allograft with rim fixation on host bone, or use of a “mega-cup”. A cementless shell that has 6 mm of lateral augmentation is useful in restoring the joint centre while at the same time achieving implant stability and increasing host bone contact without loss of additional bone. From 1991 to 2000, a total of 142 acetabular revisions were performed with the Arthropor TM DP+6 implant (Joint Medical Products/J& J/DePuy). These patients have been prospectively followed bi-annually with Harris Hip Scores and monitoring of complications and radiographic findings. Average follow-up is 5 years (range 2 to 11 years). Implant survivorship is 100%. There have been seven re-operations: one for infection (debrided), two for femoral revision and four head/liner changes for recurrent dislocations. Dislocation incidence is 7.8%. The average Total Harris Score at 5 years is 74.3, with an average Harris Pain Score of 34.9 (out of a maximum of 44). Radiographic analysis showed frequent zone 3 radiolucent zones. Initial migration of > 2 mm with subsequent stabilisation occurred in 18%. The joint centre was restored to within 5 mm of the contralateral hip in 85% of cases. We have found this type of implant to be efficacious in the more common acetabular revisions where the loss of bone stock is mainly medial/cavitary, with an intact posterior column and small medial segmental defects

Introduction. The management of periprosthetic pelvic bone loss is a challenging problem in hip revision surgery. This study evaluates the minimum 10-year clinical and radiographic outcome of major column structural allografts combined with the Burch-Schneider antiprotrusio cage for acetabular reconstruction. Methods. From January 1992 to August 2005, 106 hips with periprosthetic osteolysis underwent acetabular revision using massive allografts and the Burch-Schneider antiprotrusio cage. Forty-five patients (49 hips) died for unrelated causes without further surgery. Fifty-nine hips in 59 patients underwent clinical and radiographic evaluation at an average follow-up of 15.1 years. There were 17 male and 42 female patients, with age ranging from 29 to 83 years (mean 59). Results. Ten hips required rerevision because of infection (3), aseptic loosening (6), and flange breakage (1). Moreover, 4 cages showed x-ray signs of instability with severe bone resorption. The survivorship of the Burch-Schneider cage at 21.9 years with removal for any reason or radiographic migration and aseptic or radiographic failure as the end points were 76.3 and 81.4, respectively. The average Harris hip score improved from 33.2 points preoperatively to 75.7 points at the latest follow-up (p < 0.001). Discussion. In hip revision surgery, severe deficiency of pelvic bone stock is a critical concern because of the difficulty in providing a stable and durable fixation of the prosthesis. Although antiprotrusio cages have a limited role in acetabular revision, the use in association with massive allografts in extended bone loss demonstrated highly successful long-term results, enabling bone stock restoration and cup stability

Porous-coated acetabular hemispherical components have proven successful in all but the most severe revision acetabular defects. A revision jumbo porous coated component has been defined as cup with minimum diameter of 66 mm in men and 62 mm in women. In published studies this size cup is used in 14–39% of acetabular revisions. The advantages of this technique are ease of use, most deficiencies can be treated without structural graft, host bone contact with the porous surface is maximised, and the hip center is generally normal. Jumbo cups are typically used in Paprosky type 2, 3A, and many 3B defects. Requirements for success include circumferential acetabular exposure, an intact posterior column, and much of the posterior wall. The cup should be stable with a press-fit between the ischium and anterior superior acetabulum with the addition of some superior lateral support. Additional support is provided with multiple dome or rim screws. Survivorship of the metal shell with revision for any reason has been reported to be 80%-96% at time frames from 15–20 years. The most common post-operative complication is dislocation

There is evidence that recommends the retention of a well-fixed cement mantle at the time of revision hip arthroplasty. The cement-cement interface has been proven to have greater shear strength than a new bone-cement interface after removing a well-fixed cement mantle. This study reviewed a series of acetabular revision procedures with a minimum 2-year follow-up where the original cement mantle was left intact. From 1988 to 2004, 60 consecutive cement-in-cement revisions of the acetabular component were performed at our institution. Outcome was based on functional assessment using the Oxford, Charnley, and Harris scoring systems as well as radiographic analysis using the DeLee and Charnley criteria. In total 60 procedures were performed in 60 patients (40 female and 20 male), whose mean age at surgery was 75 years (range 40 to 99 years). 80% were performed for recurrent dislocation, 13.3% during femoral component revision, 5% for acetabular component wear, and 1.7% for pain. No case was lost to follow-up. There was one re-revision for aseptic cup loosening at 7 years, with 1 further case of radiological loosening identified at the latest review. There were 6 further cases of dislocation 4 of which were treated with further in-cement revisions. All other cases showed well-fixed components on radiographic analysis and no evidence of failure at the most recent follow up. The cement-in-cement technique already has a good body of evidence based on revision of the femoral component and this study shows that the technique can be applied to acetabular revisions as well with good functional and radiological results in the short to medium term

The indications for cementless acetabular fixation have been broadened because our data supports the use of trabecular metal cups even when there's limited bleeding host bone contact. Trabecular metal augments have allowed us to use cementless cups when there is segmental loss of bone. Surgical Technique: The acetabular bed is prepared. If there is less medial bone stock than 2 mm, then morselised allograft is impacted by reverse reaming. When reaming is complete and less than 50% bleeding host bone is available for cup stabilization, then a trabecular metal cup is indicated. Trabecular augments are used if the trabecular cup trial is not stable, or if it is uncovered by 40% or more. The conventional augments come in different sizes to accommodate the diameter of the cup and the size of the defect. Larger defects are addressed with anterior and posterior column augments, and superior defects with figure of seven augments. Augments are fixed with at least two screws. The interface between the cup and the augments should be stable, but some surgeons place a very thin layer of cement between the augment and cup so micromotion does not occur while ingrowth is occurring. We have used trabecular metal augments in 46 acetabular revisions in conjunction with a trabecular metal cup. Thirty-four cases have at least 2 years follow-up with an average of 64.5 months. There has been 4 cup loosenings with 3 re-revisions

Structural bulk autografts restore the severe bone loss at primary hip arthroplasty in dysplastic hips and have shown to have good long term outcomes. There are only a few reports of revision arthroplasty for these sockets that fail eventually. We report on a series of such primary hips which underwent cemented revision of the socket for aseptic loosening and their outcomes. A retrospective review was performed from our database to identify fifteen acetabular revisions after previous bulk autograft. The mean age at revision was 53.9 years (range 31–72.1). The mean duration between the primary and revision arthroplasty was 12.4 years (range 6.6 – 20.3). All procedures were done using trochanteric osteotomy and three hips also needed the femoral component revision. All fifteen hips needed re-bone grafting at the revision surgery to restore the new socket to the level of the true acetabulum. Of these ten hips had morsellised impaction allograft, and the remaining five also needing a structural bulk allograft. Two sockets underwent re-revision at mean 7.5 years for aseptic loosening. One patient had a dislocation that was reduced closed. At a mean follow up of 5.7 years, one socket showed superior migration, but was stable and did not need further intervention. Two other sockets also showed radiological evidence of loosening, and are being closely monitored. The medium term results of cemented acetabular revision in this younger age group are satisfactory, with repeat bone grafting being required to restore the true acetabular position. Though the primary arthroplasty with bulk bone graft recreates the acetabular bone stock, significant bone loss due to the mechanical loosening of the socket needs to be anticipated in revision surgery

Introduction. Reinforcement ring with allograft bone is commonly used for acetabular reconstruction of bone defects because it can achieve stable initial fixation of the prosthesis. It is not clear whether the allograft bone can function as a viable host bone and provide long-standing structural support. The purpose of this study was to assess to long-term survival of the reinforcement rings and allograft bone incorporation after acetabular revisions. Methods. We retrospectively reviewed 39 hips (37 patients) who underwent reconstruction of the acetabulum with a Ganz reinforcement ring and allograft bone in revision total hip arthroplasty. There were 18 females and 19 males with a mean age of 55.9 years (35–74 years). The minimum postoperative follow-up period was 10 years (10∼17 years). We assessed the acetabular bone defect using the Paprosky's classification. We determined the rates of loosening of the acetabular reconstructions, time to aseptic loosening, integration of the allograft bone, resorption of the allograft bone, and survival rate. Aseptic loosening of the acetabular component was defined as a change in the cup migration of more than 5 mm or a change in the inclination angle of more than 5° or breakage of the acetabular component at the time of the follow-up. Graft integration was defined as trabecular remodelling crossing the graft-host interface. Resorption of the allograft bone was classified as minor (<1/3), moderate (1/3–1/2) or severe (>1/2). Kaplan-Meier survivorship analysis was performed for aseptic loosening of the acetabular component. The results. The acetabular bone defects were classified as follows: 8 type II hips (4 type IIB, 4 type IIC), and 31 type III hips (17 type IIIA, 14 type IIIB). Fourteen (35.9%) of 39 hips was defined as aseptic loosening of an acetabular component. Loosening was more frequent in type IIIB (57.1%) than in type IIIA hips (29.4%). Mean time to aseptic loosening of the acetabular reconstructions was 6.3 years in type IIIA and from 5 years in type IIIB defects, respectively. Allograft bone incorporation was satisfactory in 66.7% of hips. There was minor bone resorption in 14.3% and moderate bone resorption in 10.2%. In 9 hips (23.1%), severe resorption of the allograft bone was observed and early component loosening was observed in these cases. The survival rate of acetabular component at 10 years of follow-up was 63.6% (95% confidence interval, 49–77%) with aseptic loosening as endpoints. Conclusions. The long-term survival rate of acetabular revision using the reinforcement ring and allograft bone in the reconstruction of severe acetabular bone defects was unsatisfactorily low due to loosening of acetabular components. Because of unfavorable graft incorporation into a host bone, an alternative component and structural support may be employed in the reconstruction of severe acetabular bone defects

Fracture of contemporary femoral stems is a rare occurrence. Earlier THR stems failed due to design issues or post manufacturing heat treatments that weakened the core metal. Our group identified and analyzed 4 contemporary fractured femoral stems after revision surgery in which electrochemical welds contributed to the failure.

All four stems were proximally porous coated titanium alloy components. All failures occurred in the neck region post revision surgery in an acetabular cup exchange. All were men and obese. The fractures occurred at an average of 3.6 years post THR redo (range, 1.0–6.5 years) and 8.3 years post index surgery (range, 5.5–12.0 years). To demonstrate the effect of electrocautery on retained femoral stems following revision surgery, we applied intermittent electrosurgical currents at three intensities (30, 60, 90 watts) to the polished neck surface of a titanium alloy stem under dry conditions.

At all power settings, visible discoloration and damage to the polished neck surface was observed. The localized patterns and altered metal surface features exhibited were like the electrosurgically-induced damage priorly reported.

The neck regions of all components studied displayed extensive mechanical and/or electrocautery damage in the area of fracture initiation. The use of mechanical instruments and electrocautery was documented to remove tissues in all 4 cases.

The combination of mechanical and electrocautery damage to the femoral neck and stem served as an initiation point and stress riser for subsequent fractures. The electrocautery and mechanical damage across the fracture site observed occurred iatrogenically during revision surgery. The notch effect, particularly in titanium alloys, due to mechanical and/or electrocautery damage, further reduced the fatigue strength at the fractured femoral necks. While electrocautery and mechanical dissection is often required during revision THA, these failures highlight the need for caution during this step of the procedure in cases where the femoral stem is retained.

The indications for cementless acetabular fixation have been broadened because our data supports the use of trabecular metal cups even when there's limited bleeding host bone contact. Trabecular metal augments have allowed us to use cementless cups when there is segmental loss of bone. Surgical Technique: The acetabular bed is prepared. If there is less medial bone stock than 2mm, then morselised allograft is impacted by reverse reaming. When reaming is complete and less than 50% bleeding host bone is available for cup stabilisation, then a trabecular metal cup is indicated. Trabecular augments are used if the trabecular cup trial is not stable, or if it is uncovered by 40% or more. The conventional augments come in different sizes to accommodate the diameter of the cup and the size of the defect. Larger defects are addressed with anterior and posterior column augments, and superior defects with figure of seven augments. Augments are fixed with at least two screws. The interface between the cup and the augments should be stable, but some surgeons place a very thin layer of cement between the augment and cup so micromotion does not occur while ingrowth is occurring. We have used trabecular metal augments in 46 acetabular revisions in conjunction with a trabecular metal cup. Thirty-four cases have at least 2 years follow-up with an average of 64.5 months. There have been 4 cup loosenings with 3 re-revisions

Aims: This study evaluates the clinical results of acetabular revision with Lima SPH Anatomic cup in 63 cases, performed at our Institute since 1999. Methods: We have evaluated 63 acetabular revision with SPH Anatomic cup in retrospective way. All the cases were produced by aseptic loosening and bone loss was in stage I or II according to GIR classiþcation (simple acetabular enlargement or one wall defect). The evaluation occurred after 1 to 3.5 years. Results: Preoperative mean Harris Hip Score was 54 and at time of evaluation it was 91. No sign of loosening was found. The mean cranial elevation of centre of rotation was preoperatively 13 mm and postoperatively 9 mm. Conclusions: The good results obtained with this kind of cup can be explained through its peculiarities: the emispheric design with the cranial ßange permits a press-þt þxation in presence of sufþcient bone stock and an exact-þt þxation with screws when the wall defect is important. In our opinion the 18û automatic antiversion of the implant is helpful in cases in which there is a great posterior wall defect and a traditional cup could determinate a wrong, retroverted orientation of the acetabulum. As we can see, a cranial elevation of the centre of rotation is well tolerated because less than 1 cm, and many Authors agree with us upon this consideration. In conclusion SPH Anatomic cup is a good solution for acetabular revision with minimal to moderate bone loss

The indications for cementless acetabular fixation have been broadened because our data supports the use of trabecular metal cups even when there's limited bleeding host bone contact. Trabecular metal augments have allowed us to use cementless cups when there is segmental loss of bone. Surgical Technique:. The acetabular bed is prepared. If there is less medial bone stock than 2mm, then morselised allograft is impacted by reverse reaming. When reaming is complete and less than 50% bleeding host bone is available for cup stabilization, then a trabecular metal cup is indicated. Trabecular augments are used if the trabecular cup trial is not stable, or if it is uncovered by 40% or more. The conventional augments come in different sizes to accommodate the diameter of the cup and the size of the defect. Larger defects are addressed with anterior and posterior column augments, and superior defects with figure of seven augments. Augments are fixed with at least two screws. The interface between the cup and the augments should be stable, but some surgeons place a very thin layer of cement between the augment and cup so micromotion does not occur while ingrowth is occurring. We have used trabecular metal augments in 46 acetabular revisions in conjunction with a TM cup. Thirty-four cases have at least 2 years follow-up with an average of 64.5 months. There has been 4 cup loosenings with 3 re-revisions

The indications for cementless acetabular fixation have been broadened because our data supports the use of trabecular metal cups even when there's limited bleeding host bone contact. Trabecular metal augments have allowed us to use cementless cups when there is segmental loss of bone. Surgical Technique: The acetabular bed is prepared. If there is less medial bone stock than 2 mm, then morselised allograft is impacted by reverse reaming. When reaming is complete and less than 50% bleeding host bone is available for cup stabilization, then a trabecular metal cup is indicated. Trabecular augments are used if the trabecular cup trial is not stable, or if it is uncovered by 40% or more. The conventional augments come in different sizes to accommodate the diameter of the cup and the size of the defect. Larger defects are addressed with anterior and posterior column augments, and superior defects with figure of seven augments. Augments are fixed with at least two screws. The interface between the cup and the augments should be stable, but some surgeons place a very thin layer of cement between the augment and cup so micromotion does not occur while ingrowth is occurring. We have used trabecular metal augments in 46 acetabular revisions in conjunction with a trabecular metal cup. Thirty-four cases have at least 2 years follow-up with an average of 64.5 months. There has been 4 cup loosenings with 3 re-revisions. Our most up to date data is 101 cases with an average follow-up of 3 years. There has been one infection that underwent a two stage revision. There are 4 loose cups – 3 revised

Introduction. In the case of bipolar hemiarthroplasty, surgeons are often faced with only migration of outer head and severe osteolysis in acetabulum without loosening of femoral component. There has been much debate regarding the merits of removing or retaining stable femoral components in such cases. The purpose of this study was to determine whether revision of an isolated acetabular component without the removal of a well-fixed femoral component [Fig. 1] could be successfully performed. Materials and methods. Thirty-four hips of 33 patients who were followed up for a minimum of 1 year were examined. There were 29 women and 4 men. The average time from primary operation to revision surgery was 12.5 years (range, 0.0 to 17.9 years), and the average follow-up time after revision was 5 years (range, 1.1 to 15.2 years). The average age of the patients at the time of the index revision was sixty-four years (range, thirty-two to seventy-eight years). The reason for acetabular revision was migration of outer head in twenty-eight hips, disassembly of bipolar cup in four hips and recurrent dislocation in two hips. Of the thirty-four femoral components, twenty-seven were cementless and seven were cemented. In nine hips, we performed bone grafting to osteolysis of the proximal femur around the stem. Acetabular components were revised to an acetabular reinforcement ring with a cemented cup in 26 hips, to cementless acetabular components in 8 hips, and to cemented cup in 1 hip. Results. The average Japan Orthopaedic Association hip score improved from 50.7 to 86.1 points after revision surgery. One femoral component (3%) was revised because of periprosthetic fracture, three years after the index acetabular revision and eighteen years after the initial bipolar hemiarthroplasty. Radiographic evaluation of the thirty-three femoral components that were not revised demonstrated no evidence of loosening or subsidence. There were no dislocation or deep infection. Thirty-three (97%) of the acetabular components were judged to be stable at the final follow-up. A nonprogressive radiolucent line of less than 2 mm was observed in one case. Conclusion. We recommend that isolated acetabular revision be considered in cases of failed bipolar hemiarthroplasty with a well-fixed femoral component

Aims: To study clinical and radiological outcome of acetabular revision in THR with porous, hydroxyapatite-coated cups. Methods: 50 acetabular revisions (48 patients) operated by single surgeon were reviewed. Uncemented, hydroxyapatite coated cup (Mallory/Head, Biomet) was used. Preoperative acetabular bone loss graded by Paprosky’s classification (grade 1: 12, grade 2a: 26, grade 2b: 8, 2c: 2, grade 3a: 2). Acetabulum alone was revised in 22 hips. Duration of follow up: 35 months (24–52). Clinical outcome assessment was done using Merle d’Aubigne and Postel score & QALY index questionnaire. Radiological assessment by standard X-rays taken at the latest review date. No case was lost to follow up. Results: Merle d’Aubigne & Postel scores improved from 2.1, 2.7 and 2.4 (pre-operative) to 5.0, 4.3 and 4.5 (post-operative) respectively with significant improvement in QALYs scores. Radiological assessment showed no mechanical failures. Good trabecular formation between HA-coating and the bone seen in the majority. Non-progressive radiolucency < 1mm in 6 cases, superior migration > 2 mm in 3 cups where bone graft was used, and < 2mm migration in 9 cups was noted. 2 cases had rerevision for recurrent dislocation. Conclusions: Hydroxyapatite coating on the implant may enhance bony ongrowth at bone-implant interface giving additional stability. Good midterm results obtained in our study using hydroxyapatite-coated components favour the use of this type of cup in acetabular revisions for moderate bone loss, but a long-term follow up is essential

To evaluate large/Jumbo acetabular cups in revision surgery, 52 cups in 48 patients were reviewed; mean age was 71. 6 years and mean follow up 6 years. Average Harris Hip Score was 85. Excellent bony incorporation was seen in all but the failures, of which there were three, 1 due to infection and 2 due to aseptic loosening. Major complications included 2 intraoperative fractures. Intermediate results of acetabular revisions, using large cups, without bone grafting are encouraging

Aim: to evaluate the use of large acetabular cup in revision surgery without structural bone graft. Materials/methods: Patients who had revision hip surgery at Greenwich Hospital between 1991 and 1994 were reviewed. All patients had complete clinical and radiological follow up. Large cup was the press fit Mathys Isoelastic cup. No patient had any structural bone grafting. Failure was defined as need for surgery and/or poor clinical outcome. Objective clinical assessment was done using the Harris Hip score. Radiological assessment was carried out using RC Johnston’s criteria for uncemented cups. Results: 52 revised cups in 48 patients were reviewed. Mean age was 71.6yrs, 21 males and 27 females. Mean follow up was 6 years (4 to 8 years). Average cup size was 64 mm (62 to 66). Diagnosis at index operation was 10 Rheumatoid, and 42 osteoarthrosis. Average Harris Hip Score was 85 (excellent 35, good 11, fair 3, poor 3). Radiological assessment showed excellent bony incorporation in all but the failures. There were 3 failures, 1 due to infection (revision was for infected primary THR), and 2 due to aseptic loosening in rheumatoid patients (both had significant cup malposition at revision). The major complications included 2 intraoperative fractures. Conclusion: Intermediate term results of acetabular revisions, using large cups, without structural bone grafting, in our hands, are encouraging. Cup position at revision appears crucial for long-term survival

The most challenging aspect of acetabular revision is the management of bone loss compromising implant fixation and stability. Several options, including both nonbiologic and biologic fixation, are available for acetabular revision. Biologic fixation is considered the best solution for revision surgery because it aims to restore the detoriated bone stock by using structural or cancellous allografts and a cemented polyethylene cup with impaction grafting with or without an antiprotrusio cage. With this technique, reliable and durable fixation of cemented acetabular components depend on the incorporation of allografts. Impaction grafting with use of morselized bone is a biological fixation alternative as defined by Sloof in 1984. He reported 94% survival in 11 years. Best results of this technique are obtained in contained or cavitary defects because the skeleton, while weakened, is basically intact. In these defects the anterior and posterior columns and the peripheral supporting bone for the acetabular component are intact. However, uncontained, or segmental, defects are more of a challenge. If the patient has a large segmental defect and there is no possibility of placing the implant against host bone or of restoring nearly normal anatomy, then the use of a structural bone graft may be indicated. In our revision arthroplasty series, despite the success of impaction grafting on the femoral side and on cavitary defects of the acetabulum, we had early loosening in segmentary defects with mesh or structural allograft reconstruction of the acetabular wall and impaction. Retrospectively, we have compared the survival of acetabular cup revisions with impaction grafting technique with or without reconstruction cages in 40 hips of 39 patients. There were 15 hips without cage support and 25 hips with cage reconstruction. Patient demographics and preoperative hip scores were comparable in each group. After 4 years of follow-up we have evaluated 26.3% aseptic loosening in impaction grafting alone, and 8.3% loosening in impaction with cage reconstruction. We have concluded that the metal cage allows for a better stability, protects the cancellous graft micromotion and eventually leading to a better incorporation in segmentary defects. Impaction of the cancellous bone cubes without a cage support in segmentary acetabular defects may prone to fail because of the micromotion between the cement and the graft which is not contained in stable walls

Introduction. The objective of this study was to compare the performance of the Explant Acetabular Cup Removal System (Zimmer), which has been the favored system for many surgeons during hip revision surgery, and the new EZout Powered Acetabular Revision System (Stryker). Methods. 54mm Stryker Trident® acetabular shells were inserted into the foam acetabula of 24 composite hemi-pelvises (Sawbones). The hemi-pelvises were mounted on a supporting apparatus enclosing three load cells. Strain gauges were placed on the hemipelvis, on the posterior and the anterior wall, and on the internal ischium in proximity to the acetabular fossa. A thermocouple was fixed onto the polar region of the acetabular component. One experienced orthopaedic surgeon and one resident performed mock revision surgery 6 times each per system. Results. Statistical analysis was conducted using Tukey's range test (HSD). The maximum force transferred to the implant was more than 4X lower with the EZout System regardless the surgeon experience (p=1.0E-08). Overall, recorded strains were lower for the EZout System with the higher decrease in strain (5X) observed at the posterior wall region(p=2E-08). The temperature at the interface was higher for the EZout System but never more than 37°C. Total removal time was on average reduced by a third with the EZout System (p=0.01). The calculated torque was lower for the EZout System. The amount of foam left on the cup after removal, which mimics the compromised bone, was 2.5X higher on average for the Explant System with most of the foam concentrated in the polar region. Lastly, it was observed that the polar region of each implant was reached by rotating the EZout System handpiece within a very narrow cylinder of space centered along the axis of the acetabular component compared to the Explant System, which required movement of the pivoting osteotomes within a large cone-shaped operating envelope. Discussion. Quantitatively, the EZout System required lower force, producing lower strains in the surrounding composite bone. Higher impact forces and associated increased strains may increase fracture risk. Qualitatively, the Explant System required a greater cone of movement than the EZout System requiring more space for the surgeon to leverage the handle of the tool. In addition, both surgeon and resident felt substantially greater exhaustion after using the Explant System vs. the EZout System. The resident compensated for the increased workload of the Explant with time, the experienced surgeon with force. The learning curve for both experienced surgeon and resident was also much shorter with the EZout System as shown by the close force values between the experienced surgeon and resident. Conclusion. Based on the results of this in vitro model, the EZout Powered Acetabular Removal System may be a reasonable alternative to manual removal techniques

Aim of the study: To assess the results of the uncemented oblong shaped Bofor cup in acetabular revision. Methods & materials: A prospective study from January 2001 to July 2006.15 cases of acetabular revision in 14 patients is studied. Paprosky classification for the acetabular defects is used. Final outcome assessed clinically and radiologically. Both Harris hip and Oxford hip functional scoring is used to assess the patients. None of the cases are lost in follow up. Results: The average follow-up was 36 months (range 8–52 months). All the cases were of aseptic loosening. 1case of type 2a, 6 cases of type 2b, 5 cases of type 2c, 3cases of type 3 defect and 4 cases with medial wall defect were noted. Stem was revised in 8 cases. In 4 cases auto graft from iliac crest was used. allograft was not used in any cases. In 12 cases 15 degree hooded insert was used. Average HHS improved from 30 points (range 20–38) to 84 points (range 70–90). Average OHS improved from 24 points (range 18–40) to 82 points (range 74–92). There were no cases of dislocation& infection.1 patient had sciatic nerve neuropraxia.1 case of severe Ankylosing spondylitis failed which was revised. Conclusion: Assemytical shape and design of the Boforcup makes it an useful cup for segmental and cavitatory acetabular defects. Pre operative classification of acetabular defects is inconsistent and unreliable. Allograft usage is not essential for these defects