Revision of failed acetabular components utilizing a cementless oblong cup: an average 9-year follow-up study

Introduction  Failure of acetabular components often leads to bone loss with extensive elongated defects in the surrounding bone. In these cases, reconstruction is challenging and stable fixation of the revision implant difficult. The use of an oblong cup has been described as an option for acetabular reconstruction in such revisions. We report the first long-term results obtained with this implant to date. Materials and methods  Fifty-six longitudinal oblong revision cups (LOR™) were evaluated clinically and radiologically after a follow-up of 8–12 years (average 9 years). The defects treated with the LOR™ cup ranged from Paprosky type 1–3. Allogenic cancellous bone chips were additionally used in 31 reconstructions to fill cavitary defects. Results  Based on radiological criteria, 50 acetabular implants underwent osseointegration without any definitive signs of loosening; 2 consistently exhibited zonal radiolucent lines that were always smaller than 2 mm, 1 migrated by around 3 mm. None of these cases exhibited any clinical symptoms. In 11 cases where acetabular defects manifested postoperatively, 8 were remodeled completely and 3 partially at final follow-up. Three revision implants migrated farther than 5 mm and had to be revised before 32-month follow-up. In addition, 1 septic implant failure occurred. After an average follow-up of 9 years, 93% of the investigated implants remained in situ without further revision and 95% without aseptic implant failure. Conclusion  This 12-year clinical study demonstrates that the LOR™ cup offers a successful concept for the revision of failed acetabular components that also promotes the biological reconstruction of bony defects. Compared with other methods with similarly long follow-ups, our long-term results prove this procedure has a very low rate of revision and aseptic implant failure.     

Treatment of Acetabular Bone Defect in Revision of Total Hip Arthroplasty Using 3D Printed Tantalum Acetabular Augment

Objective

The treatment of acetabular defects is one of the most difficult challenges of revision of total hip arthroplasty (RTHA), and tantalum is regarded as a promising bone substitute material. This study aims to investigate the effectiveness of 3D printed acetabular augment used in RTHA for the treatment of acetabular bone defect.

Methods

A retrospective analysis of the clinical data of seven patients who had undergone RTHA was carried out using 3D printed acetabular augment from January 2017 to December 2018. The CT data of the patients were exported to Mimics 21.0 software (Materialise, Leuven, Belgium), and the acetabular bone defect augment were designed, printed and then implanted during operation. The postoperative Harris score, visual analogue scale (VAS) score and prosthesis position were observed to evaluate the clinical outcome. A I-test was used for preoperative and postoperative comparison of the paired-design dataset.

Results

A firm attachment of the bone augment to the acetabulum during operation without any complications was found during the follow-up time 2.8–4.3 years. The VAS score of all patients was found 6.9 ± 1.4 before operation and was 0.7 ± 0.7 at the last follow-up (P ≤ 0.001), and the Harris hip scores, were 31.9 ± 10.3 and 73.3 ± 12.8 before operation, and at the last follow-up (P ≤ 0.001), respectively. Moreover, no loosening sign between the bone defect augment and the acetabulum was observed during the entire implantation period.

Conclusion

3D printed acetabular augment is effective in reconstructing the acetabulum following an acetabular bone defect revision, which enhances the hip joint function and eventually makes a satisfactory stable prosthetic.     

Cementless jumbo cups for revision of failed Furlong prosthesis. A case series

BackgroundRevision of failed total hip arthroplasty (THA) presents great challenge to any orthopaedic surgeon especially in the presence of acetabular defects where the main goal is to achieve durable fixation of prosthetic components to bone which is the key to successful revision surgery.MethodsSeventeen patients (17 hips) with mean age of 52 (40–61) years had revision surgery for aseptic failure of Furlong hydroxyapatite-ceramic-coated (HAC) prosthesis using cementless jumbo cups. Patients were reviewed clinically and radiographically with mean follow-up of 3.5 years (2–6). No patient was lost to follow up.ResultsAll revised acetabular components showed polyethylene wear, severe metallosis, with acetabular defects IIB (4/17), and IIIA (13/17) according to Paprosky classification. The femoral component was well fixed in all cases but one patient had stem revision for femoral fracture mal-union. There was one early post-operative infection; there was no postoperative dislocation, sciatic nerve injury, periprosthetic fracture or deep venous thrombosis. At last follow-up, no progressive radiolucencies or acetabular migration was identified. The mean Harris hip score improved from 42 (24–59) pre-operatively to 85 (72–92).ConclusionGood clinical results and radiographic stability were obtained at short term follow up after acetabular revision using cementless jumbo cups, which justify its use in revision surgery even in the face of major acetabular defects. Furlong HAC femoral component gives excellent long-term survival in young and active patients with a survival rate of 94% at 18.6 years.     

Cementless acetabular revision: past, present, and future

Background  

Acetabular revision is probably the most difficult aspect of hip reconstructive surgery. Although the majority of acetabular revisions can be performed using an uncemented hemispherical acetabular device with ancillary fixation, patients with severe acetabular deficiencies and poor bone quality require more complex alternatives for revision. The limitations of traditional cementless acetabular implants has promoted the development of improved methods of fixation and revision techniques. Highly porous metals have been introduced for clinical use in arthroplasty surgery over the last decade. Their higher porosity and surface friction are ideal for acetabular revision, optimising biological fixation. The use of trabecular metal cups in acetabular revision has yielded excellent clinical results.     

Pitfalls in the use of acetabular reinforcement rings in total hip revision

Introduction: For the reconstruction of acetabular bone defects different types of acetabular reinforcement rings are being used. In clinical practice, these implants showed to some extent good long-term results. In the present work pitfalls and complications after the implantation of acetabular reinforcement rings as well as possible solutions are being discussed. Material and methods: In the first case recurrent dislocation was caused by the malposition of the acetabular component with an impingement of the protruding bone cement and the anterior edge of the acetabular ring as well as muscle insufficiency as a result of the shortening of the leg length. The second case revealed an impingement of the iliopsoas tendon due to a protruding acetabular reinforcement ring. During revision, bone cement was used to smoothen the protruding anterior edge of the acetabular reconstruction ring in order to obtain a relieved sliding of the tendon. Furthermore, we report on the case of a delayed neuropathy of the sciatic nerve after reconstruction of the acetabulum with an acetabular reinforcement ring. Results: Intraoperatively an impingement of the sciatic nerve at the protruding dorsal edge of the acetabular reinforcement ring and the surrounding scar tissue was found. In a further case an aseptic loosening of an acetabular reinforcement ring caused the formation of an excessive granuloma with a large intrapelvic portion. The granuloma led to persisting senso-motoric deficits of the femoral nerve. In summary, based on these clinical cases possible pitfalls, associated with the use of acetabular reinforcement rings, are shown. The mal-positioning and the intra-operative re-shaping of the implant by the surgeon are pointed out as the substantial factors for the occurrence of an impingement phenomenon and total hip instability. Furthermore, in case of an adequate orientation of the cemented polyethylene insert an improper position of the acetabular ring which results in protruding edges has to be considered as a cause of a prosthetic impingement. Conclusion: The cases presented emphasize the necessity of prevention of such pitfalls intra-operatively as well as accurate analysis of implant failures. Furthermore, they suggest explicit preoperative planning before deciding on the strategy of revision surgery of acetabular reinforcement rings.No benefits or funds were received for this work.     

髋臼加强杯在髋臼翻修术中的应用

目的 观察髋臼加强杯在髋臼翻修手术中巨大髋臼骨缺损修复中的应用疗效.方法 2003年2月至2008年10月对12例在翻修术中存在严重髋臼骨缺损的患者采用植骨与髋臼加强杯重建髋臼骨缺损后固定假体.手术前、后情况进行临床评估及影像学评估.术前骨缺损分类按Paprosky分型:ⅡB型2例,ⅢA型6例,ⅢB型4例.术前Harris评分平均为35.2分.结果 术后所有患者均获随访,平均随访时间37个月(9～71个月);术后第一次随访时Harris评分平均为80.9分,末次随访时平均84.6分.术后假体无松动或断裂.有1例患者翻修术后6个月于髋臼Delee&Chamley Ⅲ区出现轻度放射线透亮带,但继续随访未进展.未出现假体失败而需要再次翻修病例.结论 采用髋臼加强杯联合植骨技术可有效修复髋臼骨缺损,重建髋臼结构稳定性,中短期随访疗效可靠.     

Acetabular revision using a total acetabular allograft

The most challenging aspect of an acetabular revision is the management of severe bone loss, which compromises implant fixation and stability. We present a case of failed acetabular revision with extensive bone loss (Paprosky Type 3b) in a 50-year-old woman with rheumatoid arthritis, which was treated using total acetabular allograft. At a follow-up of 1 year and 3 months, the allograft had united with the host bone. This is the first report of the use of a total acetabular allograft for revision total hip arthroplasty in India. The total acetabular allograft allows the placement of the component closer to the normal hip center, provides initial stability for the acetabular component, and restores bone stock to the host pelvis.     

The use of bilobed porous-coated acetabular components without structural bone graft for type III acetabular defects in revision total hip arthroplasty: a prospective study with a minimum 2-year follow-up

A prospective analysis was undertaken of 11 hips (in 11 patients) that underwent revision acetabuloplasties with bilobed, porous-coated, acetabular implants without the use of structural bone graft for type III acetabular defects. The average patient age was 66.3 years, with an average follow-up of 38 months (range, 24-49 months). No acetabular components required or are pending revision surgery. Average pain and hip scores improved from 8 and 36 preoperatively to 42 and 89 postoperatively, respectively. Average leg-length differences decreased from 34 mm preoperatively to 7 mm postoperatively. The use of bilobed acetabular components without structural bone graft is a feasible alternative for reconstructing type III acetabular defects, and can provide good short-term clinical results, while reconstructing the hip center and maximizing host-implant contact.     

Reconstruction of Paprosky Type III Acetabular Defects by Three‐Dimensional Printed Porous Augment: Techniques and Clinical Outcomes of 18 Consecutive Cases

ObjectiveTo introduce the surgical technique of reconstruction of Paprosky type III acetabular defects by 3D printed porous augments.MethodsFirst, CT scans of pelvis were obtained to establish the 3D reconstruction model of 3D printed porous augment. Then, a nylon pelvis model was printed to simulate operation with the surgeons. At this time, the augment was designed and modified according to the surgeon''s suggestions and the 3D printing principles. Eighteen patients with Paprosky type III acetabular defects receiving reconstructive surgery by 3D printed porous augments were included in current study. Their data, including general information, intra‐operative findings, imaging results, functional scores, and complications were retrospectively analyzed.ResultsThe mean follow‐up time lasted 33.3 ± 2.0 (24–56) months. The average limb‐length discrepancy (LLD) was 31.7 ± 4.2 (3–59) mm preoperatively, 7.7 ± 1.4 (1–21) mm postoperatively (P < 0.0001), and 7.5 ± 1.2 (0–18) mm at the latest follow‐up. The mean vertical position of hip center of rotation (HCOR) from the interteardrop line changed from preoperative 50.7 ± 3.9 (23.3–75.3) mm to postoperative 22.9 ± 1.9 (10.1–40.3) mm (P < 0.0001), with the latest follow‐up revealing an HCOR of 22.3 ± 1.7 (11.0–40.5) mm. Follow‐up study showed that no hip had radiolucencies and radiological loosening of the acetabular components and augment. The average Harris hip score (HHS) improved from 40.3 ± 4.5 (10.5–71) before operation to 88.4 ± 1.9 (75–97) at the last follow‐up (P < 0.0001). Moreover, follow‐up exhibited that no periprosthetic joint infection, hip dislocation, fracture, and re‐revision occurred.ConclusionSurgical treatment of Paprosky type III acetabular defect with 3D printed porous augment was simple, achieved good match between porous augment and the defect bone surface and the acetabular component, ideally restored LLD and HCOR after operation, significantly improved HHS and attained good early clinical outcomes. It is a promising personalized solution for patients with severe acetabular bone defect.     

Anatomic placement of the acetabular implant in cementless total hip arthroplasty does not adversely affect the implant survival and patient satisfaction

ObjectiveThis study aimed to evaluate if the acetabulum's conservative reaming with preservation of the medial acetabular bone and anatomic placement of the acetabular implant in cementless total hip arthroplasty (THA) has any adverse effect on the radiological outcome, long term implant survival and patient satisfaction.Methods106 consecutive patients were identified from a single surgeon practice who underwent cementless THA from 2005 to 2010. Twenty-one were lost to follow up, and five patients died unrelated to THA. Eighty patients were available for the study. The mean follow-up was 8.6 years (range 5.7–11.6). The mean age was 61.9 years. Immediate pre- and postoperative radiographs were reviewed to calculate combined offset (Acetabular offset – AO, plus Femoral offset – FO). Implant failure, aseptic loosening, revision surgery, patient satisfaction and complications were assessed on long-term follow-up.ResultsAcetabular component survival was 100% with no aseptic failure. None of the patients had revision surgery for any cause. The mean difference in the acetabular offset and combined offset postoperatively was within 3 mm. One patient had a dislocation, and one had a prosthetic joint infection (PJI). 95% of the patients in this series would recommend the hip replacement procedure to others, with a mean satisfaction score of 8.7 (range; 1–10).ConclusionConservative acetabular reaming with preservation of medial acetabulum bone with the anatomic placement of the acetabular implant in cementless THA is safe with no adverse effects on implant survival and patient satisfaction. It offers the advantage of preserving the patient's bone stock, which would potentially be of significant advantage to the patient and the surgeon in case of revision arthroplasty.     

Acetabular cup positioning in revision total hip arthroplasty with Paprosky type III acetabular defects: Martell radiographic analysis

Purpose

This study evaluates acetabular cup position in the setting of revision total hip arthroplasty (THA) with severe acetabular bone defects.

Methods

With a definition of safe zone of abduction (30–50°) and anteversion (5–25°), acetabular cup position was measured by a digital image analysis program for 34 patients with Paprosky type III acetabular bone defects.

Results

There were 24 cups (71 %) for abduction and 26 cups (76 %) for anteversion located in the safe zone. Nineteen cups (56 %) were within the safe zone for both abduction and anteversion. There was no dislocation, however one cup out of the safe zone resulted in early cup failure due to aseptic loosening.

Conclusions

The acetabular cup positioning in patients with Paprosky type III defects was 'optimal' in half of the cases. The prevalence of optimal acetabular cup position was similar to those reported in primary THA, suggesting that the presence of a large acetabular bone defect may not be a significant risk factor for suboptimal acetabular cup positioning in the setting of revision THA.     

Can custom 3D printed implants successfully reconstruct massive acetabular defects? A 3D-CT assessment

We report on the accuracy, measured with three-dimensional (3D) computed tomography (CT) postoperatively, in positioning custom 3D printed titanium components in patients with large acetabular defects. Twenty patients (13 females and 7 males) received custom-made acetabular implants between 2016 and 2018; the mean age was 66 years (SD = 11.6) and their mean body mass index was 28 (SD = 6.1). The median time to follow up was 25.5 months, range: 12 to 40 months. We describe a comparison method that uses the 3D models of CT-generated preoperative plans and the postoperative CT scans to quantify the discrepancy between planned and achieved component positions. Our primary outcome measures were the 3D-CT-measured difference between planned and achieved a component position in six degrees of freedom: center of rotation (CoR), component rotation, inclination (INC), and version (VER) of the cup. Our secondary outcome measures were: Oxford hip score, walking status, and complication rate. All components (100%) were positioned within 10 mm of planned CoR (in the three planes). Eighteen (95%) components were not rotated by more than 10° compared to the plan. Eleven (58%) components were positioned within 5° of planned cup angle (INC and VER). To date one complication has occurred, a periprosthetic fracture. This is the largest study in which postoperative 3D-CT measurements and clinical outcomes of custom-made acetabular components have been assessed. Accurate pre-op planning and the adoption of custom 3D printed implants show promising results in complex hip revision surgery.     

髋臼加强环联合同种异体骨植骨重建髋臼在髋关节翻修中的应用

目的总结髋臼加强环(Cage)联合同种异体骨植骨重建髋臼在髋关节翻修术中的应用及疗效。方法 2006年2月-2010年8月,对14例(14髋)行人工全髋关节翻修术的重度髋臼骨缺损患者采用Cage联合同种异体骨植骨重建髋臼。男6例,女8例;年龄45～76岁,平均59.2岁。初次置换至此次翻修术时间为5～12年,平均7.2年。翻修原因:感染8例,骨溶解及假体松动6例。术前髋关节功能Harris评分为(37.7±5.3)分。髋臼骨缺损按照美国骨科医师协会(AAOS)分型标准:Ⅲ型8例,Ⅳ型6例。结果术后切口均Ⅰ期愈合,无坐骨神经损伤、下肢深静脉血栓形成等并发症发生。患者均获随访,随访时间14～62个月,平均44个月。患者疼痛症状均明显缓解或消失。末次随访时髋关节Harris评分为(89.7±3.2)分,与术前比较差异有统计学意义(t=—44.40,P=0.04)。X线片示髋臼假体均无松动,植骨未见明显吸收,并逐渐与宿主骨融合。结论在髋关节翻修时,采用Cage联合同种异体骨植骨能有效修复髋臼骨缺损并重建髋臼,近期疗效满意,远期疗效尚需进一步随访观察。     

Revision arthroplasty--acetabular aspect: cementless acetabular bone reconstruction

The increasing occurrence of aseptic loosening, often accompanied by extensive acetabular defects, confronts the surgeon with severe difficulties. Multisegmental acetabular defects can be treated by bone grafting and metal antiprotrusion support rings. With these techniques, pelvis defects can be reconstructed to achieve a stable and permanent fixation of the acetabular component. Since 1983, more than 850 patients underwent revision surgery of the acetabular component using a reinforcement ring. Forty-one consecutive cases were available for follow-up, including clinical and radiographic examination as well as evaluation of patient history on average 7.3 years after operation. We report the follow-up results of these cases, which demonstrate that this kind of revision surgery guarantees a solid and stable situation at the acetabular component.     

Acetabular reconstruction in revision total hip arthroplasty

The number of total hip arthroplasty (THA) procedures performed annually continues to rise. Specific challenges, including acetabular bone loss, are commonly encountered at the time of revision surgery, and orthopaedic surgeons must be prepared to address them. This review focuses on topics related to acetabular reconstruction, including pre-operative patient evaluation (clinical and radiographic), pre-operative planning, common causes of acetabular failure, classification of acetabular bone loss, methods of acetabular reconstruction, and clinical results based on reconstruction method. Pre-operative patient evaluation for revision THA begins with a thorough history and physical examination as well as laboratory workup to rule out infection. Detailed radiographic evaluation and pre-operative planning are also essential and will facilitate communication amongst all members of the operative team. Although there are several ways to describe acetabular bone loss, the Paprosky classification system – defined by anterosuperior and posteroinferior acetabular column integrity – is the system most commonly used today and will guide treatment strategy. Several treatment strategies have been developed and may be termed either “cemented” (e.g. impaction grafting, ring and cage construction, structural allograft) or “uncemented” (e.g. hemispheric shell ± porous metal augment, cup-cage, custom triflange acetabular component). Although each strategy has its advantages and disadvantages, the general principles remain the same. Successful treatment depends upon detailed pre-operative assessment, planning, and team-based plan execution. Uncemented techniques that allow for biologic fixation are preferred. In the special case of pelvic discontinuity, acetabular distraction is the authors’ preferred technique. Longer term studies are still needed to evaluate the longevity of each of the various reconstruction methods presented.     

Highly porous metal shells and augments in revision hip surgery: Big hopes for big holes

Incidence of total hip revision surgery is increasing with acetabular failure being the most common cause of revision, with or without loosening of the shell. Acetabular defects at time of surgery can be challenging to treat and different techniques have been described with no clear consensus on the best modality. Trabecular metal implants, and especially the use of augments provide a unique option to manage these conditions efficiently with less morbidity, improved function and better survivability. Previous literature has suggested that the survival of this combination (trabecular metal revision shell and augment) is around 94–100% at 2 years, 92–100% at 5 years and 92% at 10 years with revision due to aseptic loosening as an end-point. We hence recommend continued the use of trabecular metal shells and augments for managing large acetabular bone defects found during revision hip arthroplasty.     

An alternative treatment option for Paprosky Type IIIb acetabular defect using multiple tantalum wedges – A case report

The treatment of severe acetabular defects in revision total hip arthroplasty (Paprosky type IIIa and IIIb) is demanding and choosing the appropriate surgical technique remains controversial. The introduction of trabecular metal augments has led to a variety of new treatment options. The authors present a case of a Paprosky Type IIIb acetabular defect due to eight subsequent revisions of the left hip. The patient was treated with an alternative treatment option using multiple tantalum wedges. Anatomical reconstruction was achieved and at 12 months follow-up, the patient was pain free and was able to walk without walking aids.     

Strategies of management of traumatic periprosthetic acetabular fractures around a pre-existing total hip arthroplasty

Introductionand aim: Traumatic peri-prosthetic fractures are relatively rare fractures that pose a significant surgical challenge. They have a fracture pattern that is different from its iatrogenic counterpart. This study aimed at reviewing the modalities of treatment of such injuries, proposing a treatment algorithm and reporting the outcomes of these injuries.Patients and methodsWe propose an algorithm for management of traumatic peri-prosthetic acetabular fractures which depends on fracture displacement, implant stability and associated bone loss.Twelve patients with traumatic peri-prosthetic acetabular fractures were treated between January 2012 and December 2018. All patients were treated surgically. Patients were allowed immediate weight bearing as pain allowed. Assessment was carried out using the Oxford Hip Score (OHS) and the Merle D’aubigné score (MDP).ResultsMean patient age 71 (range: 59–80). 8 patients underwent implant removal, fracture fixation and re-implantation of revision acetabular cup (displaced fracture, unstable implant, adequate bone stock). Three patients required acetabular reconstruction (inadequate bone stock). One patient underwent revision acetabular component. One patient suffered from recurrent dislocation that required surgical intervention. Mean follow up was 27 Months (range 12–48). Mean OHS was 36 (range 10–47). Mean MDP was 12 (range 9–18) with 80% excellent and good results.ConclusionSurgical management of peri-prosthetic acetabular fractures can produce good to excellent results provided adequate assessment and surgical planning have been carried out. Fracture displacement, implant stability and bone stock should be carefully assessed.     

Strategies of management of traumatic periprosthetic acetabular fractures around a pre-existing total hip arthroplasty

Introductionand aim: Traumatic peri-prosthetic fractures are relatively rare fractures that pose a significant surgical challenge. They have a fracture pattern that is different from its iatrogenic counterpart. This study aimed at reviewing the modalities of treatment of such injuries, proposing a treatment algorithm and reporting the outcomes of these injuries.Patients and methodsWe propose an algorithm for management of traumatic peri-prosthetic acetabular fractures which depends on fracture displacement, implant stability and associated bone loss.Twelve patients with traumatic peri-prosthetic acetabular fractures were treated between January 2012 and December 2018. All patients were treated surgically. Patients were allowed immediate weight bearing as pain allowed. Assessment was carried out using the Oxford Hip Score (OHS) and the Merle D’aubigné score (MDP).ResultsMean patient age 71 (range: 59–80). 8 patients underwent implant removal, fracture fixation and re-implantation of revision acetabular cup (displaced fracture, unstable implant, adequate bone stock). Three patients required acetabular reconstruction (inadequate bone stock). One patient underwent revision acetabular component. One patient suffered from recurrent dislocation that required surgical intervention. Mean follow up was 27 Months (range 12–48). Mean OHS was 36 (range 10–47). Mean MDP was 12 (range 9–18) with 80% excellent and good results.ConclusionSurgical management of peri-prosthetic acetabular fractures can produce good to excellent results provided adequate assessment and surgical planning have been carried out. Fracture displacement, implant stability and bone stock should be carefully assessed.     

An oblong revision cup for large acetabular defects: Design rationale and two- to seven-year follow-up

Loosening and migration of acetabular components often lead to extensive bony defects with an elongated, oval acetabular cavity. In these cases standard implants will not reestablish and maintain sufficient stability without leaving bone defects or using massive bone grafts or excess cement and additional metal rings or shells, disadvantages that are overcome by using an oblong revision cup without cement. The titanium shell is available in different sizes, is screwed to the autochthonous acetabular bone and houses an oblong polyethylene inlay, designed to reestablish the normal anatomic hip center. Of 109 consecutive revision cups, 102, implanted for American Academy of Orthopaedic Surgeons (AAOS) defects types I–IV, were followed up clinically and radiologically for 2 to 7 years (mean, 3.6 years). Primary stability was achieved in all cases. In 40% no bone grafting was necessary at all. The radiological follow-up revealed good remodeling of the surrounding bone and osseointegration of the implants. Zonal radiolucent lines, always smaller than 2 mm, were seen in 18 cases, only once completely and in only 5 cases partially progressing. Six cups migrated slightly (≤2 mm), two moderately (3–5 mm), all without clinical symptoms, and two more than 5 mm. Migration and radiolucencies were mainly seen in patients with allografts and major defects, which indicates that bone ingrowth appears more unlikely in such cases. Few asymptomatic cases showed zonal sclerotic lines. There were two aseptic loosenings, one in a case with pelvic discontinuity, the other in a patient with severe rheumatoid arthritis following two previous revisions. Survivorship analysis based on implant removal because of aseptic loosening as the endpoint shows a cumulative success rate of 98.1% at 8 years.