The purpose of our study was to find out the midterm results of the Müller acetabular roof reinforcement ring in primary and revision total hip arthroplasty. From 1988 to 1998, 48 total hip arthroplasties using the acetabular roof reinforcement ring (39 patients) was performed by one surgeon (PDB). We reviewed all patients who had a minimum of five year follow up. There were 37 hips (31 patients) with a mean follow up of 7 years (5 to 12 years). Acetabular deficiencies were classified according to the AAOS classification. Acetabular reconstruction was done using the Müller acetabular roof reinforcement ring with the polyethylene cup cemented to the ring, and morcellized cancellous bone graft. Müller straight stem femoral prosthesis was used in all cases for femoral reconstruction. All patients were followed up annually and outcome assessed using Harris hip score. There were 27 primary procedures and 10 revisions. 30 patients (81%) had cavitary, 2 (5%) had segmental and 5 (14%) had combined defects. Survival analysis was done with failure defined as radiological evidence of loosening of the acetabular component. Statistical analysis was done using SPSS for Windows (SPSS Inc, Chicago, Illinois). 5 patients died due to unrelated causes and 2 patients were lost for follow up. The mean Harris hip score improved from 42 preoperatively to 82 postoperatively (p< 0. 001)(Wilcoxon Signed Rank test). Both mean pain and function score showed improvement from 12 to 39 postoperatively (p< 0. 001) and 12 to 32 (p< 0. 001) respectively. 5 patients had radiological loosening of the ring. The migration rate was 13%. The cumulative survival rate at 12 years, excluding all patients who died and were lost for follow up, was 79. 3% (95% confidence interval 71. 4 to 87. 2, standard error 4). There was no statistical difference in the failure rate between primary and revision procedures (chi-square test). This series show satisfactory medium term results with Müller roof reinforcement ring and cancellous bone graft in acetabular deficiencies with poor bone stock

We wanted to evaluate the clinical and radiological results of acetabular revision using the acetabular reinforcement ring and allograft impaction in patients with severe acetabular bony defect. 41 hips revision arthroplasty using reinforcement ring were performed between April 1997 and October 2005 and were followed up for more than two years. The cause of primary arthroplasty was AVN in 18 cases, secondary osteoarthritis (OA) in 17 cases, fracture in cases and primary OA in 1 case. The cause of revision arthroplasty was acetabular cup loosening in 20 cases, massive osteolysis in 14 cases, infection in 4 cases, liner dissociation in 2 cases, and recurrent dislocation in 1 case. The average period between primary and revision arthroplasty was 11.4 years (range 0.6 to 29.1 years). Acetabular defects were classified based on the AAOS classification and Paprosky classification system. All were treated with autografts or allografts. Muller ring was used in 18 cases, Burch-Schneider ring was used in 14 cases, and Ganz ring in 9 cases. Clinical evaluations were performed according to the Harris hip score (HHS), and the radiographic results were evaluated by progression of acetabular component loosening, union of bone grafts, periacetabular osteolysis, and migration of the hip center. The mean preoperative Harris hip score of 64.9 was improved to 91.8 points at the latest follow-up. There were 39 cases of type 3 defect, 2 cases of type 4 defect according to the AAOS classification and 8 cases of type 2B defect, 3 cases of type 2C defect, 28 cases of type 3A defect, and 2 cases of type 3B defect according to Paprosky classification. Radiographically, the bone grafts were well united except one case. The mean preoperative hip center of rotation which was vertically 32.3mm, horizontally 33.2 mm migrated to vertically 26 mm, horizontally 33.2 mm postoperatively and it was statistically significant. The mean preoperative abductor lever arm of 41.7 mm changed to 45 mm postoperatively which was statistically insignificant. However the mean preoperatiave body lever arm of 89.4 mm changed to 96.9 mm postoperatively which was statistically significant. Postoperative complications were cup loosening in 1 case, dislocation in 2 cases, and recurrence of deep infection in 1 case. Clinically and radiographically, acetabular reconstruction using reinforcement ring showed very promising short term result. We conclude that reinforcement ring can provide stable support for grafted bone in severe bone defect. But meticulous surgical technique to get initial firm stability of ring and optimal indication in mandactory for the successful result

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

The study reviews 24 patients with 27 total hip arthroplasties in which an acetabular reinforcement ring with hook was used for primary total hip arthroplasty (THA) due to underlying hip dysplasia. There were 19 female and 5 male patients with a mean age of 50.6 years (31 to 70) at the time of surgery. A bulk autograft for acetabular reconstruction was used in four cases with Crowe Type III and IV dysplasia. In eight cases cancellous bone alone was used to fill the gap between the reinforcement ring and the acetabulum. All patients had a polyethylene cup cemented into the ring and 22 cases had a straight Müller CDH stem cemented into the shaft. Mean follow-up was 10.7 years (range: 8.1 to 12.7). No clinical or radiographic signs of loosening of the reinforcement ring were found in 24 (88.9 %) of the 27 THAs. Two revisions (7.4%) were performed for aseptic loosening and one acetabular component had radiographic signs of loosening. The Merle D`Aubigné score had increased from 7 to 15 points. The acetabular reinforcement ring continues to have favourable results in this specific patient group and may also prevent graft resorption and cup migration

The study reviews 24 patients with 27 total hip arthroplasties in which an acetabular reinforcement ring with hook was used for primary total hip arthroplasty (THA) due to underlying hip dysplasia. There were 19 female and 5 male patients with a mean age of 50.6 years (31 to 70) at the time of surgery. A bulk autograft for acetabular reconstruction was used in four cases with Crowe Type III and IV dysplasia. In eight cases cancellous bone alone was used to fill the gap between the reinforcement ring and the acetabulum. All patients had a polyethylene cup cemented into the ring and 22 cases had a straight Müller CDH stem cemented into the shaft. Mean follow-up was 10.7 years (range: 8.1 to 12.7). No clinical or radiographic signs of loosening of the reinforcement ring were found in 24 (88.9 %) of the 27 THAs. Two revisions (7.4%) were performed for aseptic loosening and one acetabular component had radiographic signs of loosening. The Merle D`Aubigné score had increased from 7 to 15 points. The acetabular reinforcement ring continues to have favourable results in this specific patient group and may also prevent graft resorption and cup migration

In severe hip dysplasia the fixation of the cup becomes a technical hazard, and the augmentation of the acetabulum with an autologous bone graft is helpful when the bone stock is deficient. Twenty-four patients (25 hips) were operated on between 1993 and 1994; the mean age at operation was 49 years (range, 28 to 71 years). The mean Sharp acetabular angle was 55degrees (range, 45 to 63degrees). The dislocation of the femoral head was graded Crowe 1 in 4 hips, grade II in 5 hips, Grade III in 10 hips, and grade IV in 6 hips. Autologus bone was harvested from the femoral head and from the proximal metaphysis of the femur. The fixation of the graft to the anterior wall and to the roof of the acetabulum was achieved using impaction using the reinforcement ring with hook of Ganz. A separate cohort of 25 patients (25 hips) operated on between 1998 and 1999 was investigated using radiostereometry (RSA). The clinical outcome of the hips was prospectively reviewed using the Harris hip score at an average of 8.3 years (range 8 to 9 years) postoperatively. Twenty-four hips were pain-free, and had a range of motion of 210 degrees or more except 3. A positive Trendelenburg sign disappeared in 88% of the hips. One cup (4%) showed radiological loosening with migration and required revision surgery. No signs of migration or progressive radiolucent lines were present in the remaining hips. The graft appeared united without resorption in 24 hips. The results of micromotion analysis using RSA confirm the stable fixation of the reinforcement ring in dysplasia. Satisfactory middle term results of total hip replacement for severe dysplasia can be achieved using appropriate surgery and specific components. The use of reinforcement ring is important to obtain adequate primary stability, and to protect the graft during healing

Management of severe acetabular bone loss at the time of revision total hip replacements (THR) remains has been one of the greater challenges for hip surgeon. Recently, many methods of acetabular reconstruction have been described and various materials are used for supplement of the bone stock deficiency in acetabular revision THR. The purpose of this study was to evaluate the midterm results of the using support ring with bone allografts in acetabular revision THR. From 1990 to 2005, forty-six acetabular revisions using supporting ring with bone allografts were performed at our institution. All patients were followed up for a minimum of three years with a mean follow-up of 7.5 years. Pre-operative radiological acetabular bone defects were assessed and classified by author’s classification (Itoman’s classification). Radiological analysis involved a general qualitative evaluation. The position of the acetabular reinforcement ring was measured on radiograms, taken immediately after revision surgery and again at the time of last follow-up. Using a MEM template, cranio-central migration and cup inclination angle were measured. Kaplan-Meier survivorship analysis was performed. The end point was revision because of mechanical loosening of the acetabular implant. We used thirty-six Ganz rings, six Müller rings, three Kerboull T-plate and two Burch-Schneider anti-protrusion cages. The acetabular bone defects were classified as: 10 hips Type B (central defect), 9 hips Type C (cranial defect), 27 hips Type D (cranial-central defect). Migration of acetabular component was defined as a change of > 5mm in the cranial or central direction of the cup or a change in the cup inclination angle of > 5° at the time of last follow-up. All the Eleven acetabular components which had defined as loose were Type D. One acetabular component was revised because of mechanical loosening, four were revised because of infection, and one was broken polyethylene liner. Kaplan-Meier survivorship of these reconstructions was 96.2 % at 10 years. Allograft reconstruction of acetabular bone defect in revision total hip replacement is beneficial procedure. The remaining pelvic bone is usually in poor condition, therefore, it is necessary to ensure primary fixation with the reinforcement ring with bone allografts

Introduction: Treatment of acetabular defects can be difficult, especially in case of roof destruction. Since 9 years, we use a variant of Paprosky’s technique which consists in rebuilding the roof by structural allograft and acetabular reinforcement ring. The purpose of this study is to present this technique and the follow up results. Patients: This retrospective study concerns 21 patients (23 hips) with severe acetabular bone loss (8 cases of stage 2 and 15 cases of stage 3 of Paprosky): 4 septical and 19 aseptical loosening. Between 1998 and 2005, all patients were operated with the same surgical technique using an allogeneic structural allograft (femoral head or distal femur) and an acetabular reinforcement ring (20 of KERBOULL, 3 of GANZ) associated with a cemented PE cup. Method: Review included a clinical and X-ray evaluation (analysis of the refocusing of the hip, the positioning and the stability of implants and the graft incorporation). Results: Mean duration of follow-up is 3,5 years [1–8,3]. Preoperative PMA score rised from 6,6 [0–12] to 15,8 [12–18] in postoperative. There was no peroperative complication. After surgery, 2 cases of early hip dislocation required PE block; 2 cases of sepsis were treated, one by washing and one by a surgical revision. In 60% of cases, immediate total weight bearing was allowed. The immediate postoperative X-rays showed that the rotation center of the hip was 5,2 mm [0–10] far from the ideal rotation center (26% of cases: 0 mm) and the PE cup was implanted with a lateral inclination of 42,5° [30–55]. In postoperative X-ray follow up, one case of acetabular aseptic loosening was found which didn’t need hip revision. In all other cases no modification of implants position neither of hip rotation center was noted. In 79% of cases, we had total graft incorporation; in 17% of cases, an non evolutive radiolucent area between graft and bone and in 4% of cases (loosening) a graft migration. Conclusion: The use of a structural allograft combined with acetabular reinforcement ring allows hip reconstruction in severe acetabular bone loss with good medium term results

Introduction: The Acetabular Reinforcement Ring (ARR) (ME Müller®) was introduced in 1977 as successor of the Endler ring, especially to allow total hip replacement (THR) in patients with congenital hip dislocation, serious dysplasia and revision of loose cups. The Polyethylen (PE)-inlay can be freely oriented in the fixed ARR. It is the first implant with screws having angular stability as the screw-heads are blocked when cementing the inlay in the ring. Patients and Methods: Out of 2251 primary THR performed between 1984 and 2005 at our hospital the ARR was used in 399 hips (363 patients). The indication for a THR with ARR was mainly a deficient acetabular bone stock as judged by the operating surgeon. 51 % of the patients had osteoarthritis, 22% dysplasia, 7% fractures, 6,5% osteonecrosis, 5% protrusion acetabuli, 4% rheumatoid arthritis and 4,5% other diagnosis. The mean age at operation was 66.4 years, 64% were females. Intraoperatively, the ARR was placed with its medial border adjacent to the tear drop figure. The weight bearing area was fixed with 3–4 cancellous screws in the acetabular bone stock. Regular clinical and radiological follow-up 3months, 1, 2, 5, 10,15 and 20 years was planned. The radiographs were assessed for osteolysis, radiolucent lines and screw breakage after 15 years. Survival for revision due to aseptic loosening was calculated by Kaplan Meier. Results: The overall survival regarding aseptic loosening of the cup was 100% after 10 years, 97,2% after 15 and 93,2% after 20 years. Of the 96 patients (104 rings) operated at least 15 years ago, one was lost for follow-up. Three rings were revised due to aseptic loosening (11, 12, 16 years after implantation) and one was removed due to infection (1,8 years after implantation). 54 patients (with 56 rings) died before they reached the 15 years control. None of them was revised for aseptic loosening of the ring. 37 patients (43 hips) remained for 15-years control, six of them refused to come and were contacted by questionnaire or phone. Two cups were radiologically loose with broken screws but not symptomatic. The mean HHS after 15 years was 80.1. Conclusion: The ARR shows a very good long term survival even in patients with difficult acetabular situations such as deficient bone stock. The design allows an application in a variety of positions. Even at a teaching hospital good long term results could be reached with this implant

Introduction. To report the short to medium term results of acetabular reconstruction using reinforcement/reconstruction ring, morcellised femoral head allograft and cemented metal on metal cup. Methods. Single centre retrospective study of 6 consecutive patients who underwent acetabular reconstruction for revision hip surgery. The acetabulum was reconstructed using morcellised femoral head allograft and reinforcement or reconstruction ring fixed with screws. The Birmingham cup – designed for cementless fixation, was cemented into the ring in all cases. The uncemented Echelon stem with metal on metal modular head was used for reconstructing the femur. Data from our previous in-vitro study had shown good pull out strength of a cemented Birmingham cup. Results. There were 2 men and 4 women with a mean age of 75 years(57-83). Revision was performed for aseptic loosening in 2, septic loosening in 2 and peri-prosthetic fracture with loosening in 2 patients. All patients were reviewed clinically and radiographically at a mean of 36 months follow-up(range 24 - 42 months). Revision was not necessary in any patient for failure of acetabular or femoral fixation. However, 1 patient had revision to a proximal femoral replacement and constrained cup for recurrent infection and osteomyelitis at 24 months. This patient was excluded from the final analysis. The mean Harris hip score at last follow up was 79(range 70-89). Radiographic analysis revealed good graft incorporation and no signs of loosening or cup/ring migration. No dislocations or metal ion problems were recorded in this series. Conclusions. To the best our knowledge, this is the first series using cemented metal on metal cups within a reinforcement/reconstruction ring for revision hip arthroplasty. Excellent cemented fixation of the cup, manufactured for cementless fixation, was obtained at surgery with no evidence of loosening, and no dislocations at minimum 24 months follow up

Total hip arthroplasty for developmental dysplasia of the hip (DDH) remains a difficult and challenging problem. How to reconstruct acetabular deficiencies has become increasingly important. One of the major causes inducing loosening of acetabular reinforcement ring with hook (Ganz ring) is insufficient initial stability. In this study, three-dimensional finite element models of the pelvis with different degrees of bone defect and acetabular components were developed to investigate the effects of the number of screws, screw insert position (Fig. 1), and bone graf quality on the initial stability under the peak load during normal walking. The size of pelvic bone defect, the number of screws and the position of screws were varied, according to clinical experience, to assess the change of initial stability of the Ganz ring. The Ganz ring was placed in the true acetabulum and the acetabular cup was cemented into the Ganz ring with 45 degrees abduction and 15 degrees of screws. The Insert position, nodes on the sacroiliac joint and the pubic symphysis were fixed in all degrees of freedom as the boundary condition. The peak load during normal walking condition was applied to the center of the femoral head (Fig. 2). According to the Crowe classification, as the degree of acetabular dysplasia was increased, the relative micromotion between the Ganz ring and pelvis was also increased. The peak micromotion increased as the stiffness of bone graft decreased. Increasing the numbers of screws, the relative micromotion tended to be reduced and varied the screw insertion position that affects the relative micromotion in the Ganz ring-pelvic interface (Fig. 3). This study showed that increasing the number of inserted screws can reduce the relative micromotion. Both the insert position and graft bone property affect the stability of the Ganz ring while the insert position has a greater impact. The current study is designed to lay the foundation for a biomechanical rationale that will support the choice of treatment

We reviewed 64 patients in whom 66 acetabula had been reconstructed with either the Muller ring (46) or the Burch-Schneider anti-protrusio cage (20) at a mean follow-up of five years. Five hips had been revised a second time for loosening, all after a Muller ring had been used for a medial segmental defect (2), ungrafted cavitary defects (2) or after resorption of a block graft (1). The use of bone grafts with the implants reduced the incidence of failure from 13% to 6% and of circumferential radiolucent lines at the bone-implant interface from 39% to 2%. The Muller ring is indicated for acetabula with isolated peripheral segmental defects or cavitary defects confined to one or two sectors. The Burch-Schneider cage should be used for medial segmental defects, extensive cavitary defects and combined deficiencies. Defects should be reconstituted with bone graft rather than cement.

We retrospectively reviewed 44 consecutive patients (50 hips) who underwent acetabular re-revision after a failed previous revision that had been performed using structural or morcellised allograft bone, with a cage or ring for uncontained defects. Of the 50 previous revisions, 41 cages and nine rings were used with allografts for 14 minor-column and 36 major-column defects. We routinely assessed the size of the acetabular bone defect at the time of revision and re-revision surgery. This allowed us to assess whether host bone stock was restored. We also assessed the outcome of re-revision surgery in these circumstances by means of radiological characteristics, rates of failure and modes of failure. We subsequently investigated the factors that may affect the potential for the restoration of bone stock and the durability of the re-revision reconstruction using multivariate analysis.

At the time of re-revision, there were ten host acetabula with no significant defects, 14 with contained defects, nine with minor-column, seven with major-column defects and ten with pelvic discontinuity. When bone defects at re-revision were compared with those at the previous revision, there was restoration of bone stock in 31 hips, deterioration of bone stock in nine and remained unchanged in ten. This was a significant improvement (p <  0.001). Morselised allografting at the index revision was not associated with the restoration of bone stock.

In 17 hips (34%), re-revision was possible using a simple acetabular component without allograft, augments, rings or cages. There were 47 patients with a mean follow-up of 70 months (6 to 146) available for survival analysis. Within this group, the successful cases had a minimum follow-up of two years after re-revision. There were 22 clinical or radiological failures (46.7%), 18 of which were due to aseptic loosening. The five and ten year Kaplan–Meier survival rate was 75% (95% CI, 60 to 86) and 56% (95% CI, 40 to 70) respectively with aseptic loosening as the endpoint. The rate of aseptic loosening was higher for hips with pelvic discontinuity (p = 0.049) and less when the allograft had been in place for longer periods (p = 0.040).

The use of a cage or ring over structural allograft bone for massive uncontained defects in acetabular revision can restore host bone stock and facilitate subsequent re-revision surgery to a certain extent.

Cite this article: Bone Joint J 2014;96-B:319–24.

Deficiencies of acetabular bone stock at revision hip replacement were reconstructed with two different types of allograft using impaction bone grafting and a Burch-Schneider reinforcement ring. We compared a standard frozen non-irradiated bone bank allograft (group A) with a freeze-dried irradiated bone allograft, vitalised with autologous marrow (group B). We studied 78 patients (79 hips), of whom 87% (69 hips) had type III acetabular defects according to the American Academy of Orthopaedic Surgeons classification at a mean of 31.4 months (14 to 51) after surgery. At the latest follow-up, the mean Harris hip score was 69.9 points (13.5 to 97.1) in group A and 71.0 points (11.5 to 96.5) in group B. Each hip showed evidence of trabeculation and incorporation of the allograft with no acetabular loosening. These results suggest that the use of an acetabular reinforcement ring and a living composite of sterile allograft and autologous marrow appears to be a method of reconstructing acetabular deficiencies which gives comparable results to current forms of treatment

We present our experience from use of acetabular reinforcement rings in revision total hip arthroplasty when bone defects are present. From 1987 to 2000, acetabular reinforcement rings were utilized in 59 revisions, in 52 patients with a mean age of 60 years (31–81). In 48 hips, Ganz rings were used and in 11 hips, Burch-Sch-neider rings. For the existing defects of the acetabulum, morsellized bone allograft was used. The patients were evaluated clinically with the modified Merle d’ Aubigne-Postel scale and radiologically with the criteria of Gill-Sledge-Muller. Acetabular reconstruction was successful in 51 of 59 hips (86.5%) after a mean follow-up period of 7 years (2–15). One of the 11 Burch-Schneider rings failed (9.1%) and 7 of the 48 Ganz, raising the failure rate of this ring up to 14.6%. Complications included dislocation in 5 cases, deep vein thrombosis in 2, superficial infection in 1 and pubis rami fracture in 2 cases. Reinforcement rings in our opinion could be of valuable help in reconstruction of the bone deficient acetabulum. Although in this study, it is not possible for these two rings to be directly compared, Burch-Schneider one appears to have a more clear role and lower failure rate. However, in order to evaluate in a more reliable way the true fate of the acetabular reinforcement rings, especially in the presence of the limited role of biological fixation, longer follow-up time is needed

Instability and aseptic loosening are the two main complications after revision total hip arthroplasty (rTHA). Dual-mobility (DM) cups were shown to counteract implant instability during rTHA. To our knowledge, no study evaluated the 10-year outcomes of rTHA using DM cups, cemented into a metal reinforcement ring, in cases of severe acetabular bone loss. We hypothesized that using a DM cup cemented into a metal ring is a reliable technique for rTHA at 10 years, with few revisions for acetabular loosening and/or instability. This is a retrospective study of 77 rTHA cases with severe acetabular bone loss (Paprosky ≥ 2C) treated exclusively with a DM cup (NOVAE STICK; SERF, DÉCINES-CHARPIEU, FRANCE) cemented into a cage (Kerboull cross, Burch-Schneider, or ARM rings). Clinical scores and radiological assessments were performed preoperatively and at the last follow-up. The main endpoints were revision surgery for aseptic loosening or recurring dislocation. With a mean follow-up of 10.7 years [2.1-16.2], 3 patients were reoperated because of aseptic acetabular loosening (3.9%) at 9.6 years [7-12]. Seven patients (9.45%) dislocated their hip implant, only 1 suffered from chronic instability (1.3%). Cup survivorship was 96.1% at 10 years. No sign of progressive radiolucent lines were found and bone graft integration was satisfactory for 91% of the patients. The use of a DM cup cemented into a metal ring during rTHA with complex acetabular bone loss was associated with low revision rates for either acetabular loosening or chronic instability at 10 years. That's why we also recommend DM cup for all high risk of dislocation situations

Aims: Acetabular reinforcement rings have been designed to deal with severe acetabular bone deþciencies in revision arthroplasty of the hip. We report midterm results of 3 different designs. Methods: Between 1986 and 2001, 346 ace-tabular revisions with reinforcement rings were performed at our institution. 20 Burch-Schneider Cages, 135 Ganz and 191 Mueller Rings were implanted. Average Age of the patients at the time of the intervention was 67 years (range 27–93 years). The average follow-up was 4 years (range 1–15 years). Bone defects were classiþed according to the AAOS-Classiþcation. Homologous allografts were used in most cases to reconstruct the acetabulum. Three different techniques were used for allograft preparation: Bone chips, bulk and morselized allografts. Results: Clinical results were moderate in most cases as multiple revisions or other disabling conditions have inßuenced the outcome. Mid-term survival was > 90% at 4 years. An attempt was made to correlate aseptic loosening with allograft preparation methods. Conclusions: Satisfactory results can be achieved at midterm using all three devices. However resorption of allografts leading to migration, dislocation or failure remain a major concern when acetabular reconstruction is used in revision hip arthroplasty

Roof reinforcement and reconstruction rings have facilitated bone restoration in revision arthroplasty of the acetabulum. These rings are used when there is not enough bone to support a conventional cemented or a standard sized or jumbo uncemented cup. Both rings may be used with morselised or structural allograft bone. Roof reinforcement rings are used for contained defects but contact must be made with host bone superiorly and infero-medially. For more global contained defects where most of the acetabulum is filled with morselised allograft bone, contact with host acetabulum infero-medially is impossible. Under these circumstances a reconstruction ring that extends from ilium to ischium must be used. Uncontained (segmental) bone defects reconstructed with structural allografts are bridged and protected by reconstruction rings that extend from ilium to ischium. In 43 acetabular revisions, roof reinforcement rings were used with morselised allograft bone for contained defects. At five years average follow-up the survivorship was 88% (one re-revision and four definitely loose). In 13 patients with massive uncontained acetabular defects, reconstruction rings were used in conjunction with structural allografts. At an average follow-up of 10.5 years, the survivorship was 77% (10 hips have not been re-revised and have a stable implant)

Introduction and Objective. The surgical strategy for acetabular component revision is determined by available host bone stock. Acetabular bone deficiencies vary from cavitary or segmental defects to complete discontinuity. For segmental acetabular defects with more than 50% of the graft supporting the cup it is recommended the application of reinforcement ring or ilioischial antiprotrusio devices. Acetabular reconstruction with the use of the antiprotrusion cage (APC) and allografts represents a reliable procedure to manage severe periprosthetic deficiencies with highly successful long-term outcomes in revision arthroplasty. Objective. We present our experience, results, critical issues and technical innovations aimed at improving survival rates of antiprotrusio cages. Materials and Methods. From 2004 to 2019 we performed 69 revisions of the acetabulum using defrosted morcellized bone graft and the Burch Schneider anti-protrusion cage. The approach was direct lateral in 25 cases, direct anterior in 44. Patients were re-evaluated with standard radiography and clinical examination. Results. Eight patients died from causes not related to surgery, and two patients were not available for follow up. Five patients were reviewed for, respectively, non-osseointegration of the ring, post-traumatic loosening with rupture of the screws preceded by the appearance of supero-medial radiolucency, post-traumatic rupture of the distal flange, post-traumatic rupture of the cemented polyethylene-ceramic insert, and dislocation treated with new dual-mobility insert. Among these cases, the first three did not show macroscopic signs of osseointegration of the ring, and the only areas of stability were represented by the bone-cement contact at the holes in the ring. Although radiographic studies have shown fast remodeling of the bone graft and the implant survival range from 70% to 100% in the 10-year follow up, the actual osseointegration of the ring has yet to be clarified. To improve osseointegration of the currently available APC whose metal surface in contact with the bone is sandblasted, we combined the main features of the APC design long validated by surgical experience with the 3D-Metal Technology for high porosity of the external surface already applied to and validated with the press fit cups. The new APC design is produced with the 3D-Metal technology using Titanium alloy (Ti6Al4V ELI) that Improves fatigue resistance, primary stability and favorable environment for bone graft ingrowth. We preview the results of the first cases with short-term follow up. Conclusions. Acetabular reconstruction with impacted morcellized bone graft and APC is a current and reliable surgical technique that allows the restoration of bone loss with a high survival rate of the implant in the medium to long term. The new 3D Metal Cage is designed to offer high friction for the initial stability. The high porosity of the 3D Metal structure creates a favorable environment for bone growth, thus providing valid secondary fixation reproducing the results achieved with the 3D metal press fit cup

Background. There are many difficulties during performing total hip replacement in high riding DDH. These difficulties include:. In Acetabular part: bony defect in antero lateral acetabular wall/finding true centre of rotation/shallowness of true acetabulum/hypertrophied and thick capsular obstacle between true and false acetabulum. In Femoral part: small diameter femoral shaft/excessive ante version/posterior placement of greater trochanter. anatomic changes in soft tissue & neurovascular around the hip including: adductor muscle contracture/shortening of abductor muscles/risk of sciatic nerve injury following lengthening of the limb after reduction in true acetabulum/vascular injury. The purpose of this lecture is how to manage above problems with using reinforcement ring (ARR) for reconstruction of true acetabulum and step cut L fashion proximal femoral neck shortening osteotomy in a single stage operation. Method. 23 surgeries in 19 patients, including 18 female and one male were performed by me from Jan. 1997 till Dec. 2009. Six patients had bilateral hip dislocation, but till now only four of them had bilateral stepped operation. Left hip was involved in 15 cases (65.2%). The average age was 40 years old. All hips were high riding DDH according to both hartofillokides and crowe classification. Reconstruction of true acetabulum was performed with aid of reinforcement ring and bone graft from femoral head in all cases. Trochantric osteotomy was done in all, followed by fixation with wire in 22 cases which needed two revisions due to symptomatic non union (9%). Hooked plate was use in one case for trochantric fixation. Due to high riding femur, it was necessary to performed femoral shortening in neck area as a step cut L fashion. In two patient, one with bilateral involvement, after excessive limb lengthening following trial reduction, it was necessary to performed concomitant supracondylar femoral shortening. (3 cases = 13%). 22 mm cup & miniature muller DDH stem were used in 18 cases (78.26%). In 5 cases, one bilaterally, non cemented stem and 28 mm cemented cup in ring were used. Primary adductor tenotomy was performed in 9 cases. Secondary adductor tenotomy needed in 2 cases (totally = 47.82%). Repair of iatrogenic femoral artery tear after traction injury with retractor, occurred in 2 cases (8.69%). All patients evaluate retrospectively. Average follow up month is 68.7. Results. One case of left acetabular component revision due to painful bony absorption in infero medial part of ring with poor inclination wad done, after 2 years of primary operation. Know after 13 years she has had early signs of stem loosening in the same side. Another acetabular component revision following traumatic dislodgment of cup and cement from ring was performed after 13 months from primary operation. Again she had poor implant inclination. So revision rate is 8.69%. (One case will need revision in near future, so the revision rate will increase to 13%) Radiological wires breakage which were used for greater trochanteric fixation, could be seen in 11 cases (47.82%), but only two of them with functional impairment needed to re-fixation with Menen plate(18.18% of trochanteric non union). Average limb lengthening after operation is 4.3 Cm (2-7 Cm). Only one case of transient Sciatic nerve paresis had happened for 2 months followed by complete recovery. Two case of secondary adductor tenotomy wre done, one after traumatic dislocation of prosthesis with pubic fracture, and the other one after restriction of hip abduction. The average Harris hip score from 23 pre -operatively has been increase to 85.38. (The pre op. scores were 12.625 – 40.775/The post op. scores were 64.92 – 96). No post operative infection was seen. Discussion. This is a midterm follow up survey, but 7 cases have more than 9 years follow up with only one stem loosening (11% long term loosening rate). It is a challenging procedure for performing joint replacement in high riding DDH, if so using reinforcement ring with graft for true acetabulum reconstruction and getting primary proximal femoral shortening in a step cut L fashion around the lesser trochanteric region would be a worthy procedure. In high riding DDH due to hypoplasia of lesser trochanter, there is not a significant difference in bone resistance and it is possible to get shortening in this area without fearing of deco promising bony stability. The average shortening is 3 Cm. In specific cases with more severe contracture for preventing neuro-vascular complication, concomitant shortening osteotomy in supracondylar area is recommended. Although greater trochanter fibrous union has produced less functional impairment, but a better technique should be considered. Distal and lateral advancement of osteotomised greater trochanter lead to better abductor muscle performance and less limp. Adductor tenotmy has a great importance in contracted soft tissue, so in any case with abduction limitation it should be performed