Dual massive skeletal allograft in revision total knee arthroplasty

The reconstruction of large uncontained defects represents a major challenge to the revision total knee surgeon, and the outcome of the revision often depends on the management of these bone deficiencies. We report the first successful use of both complete distal femoral and proximal tibia massive allografts in the reconstruction of large femoral and tibial uncontained defects during revision total knee arthroplasty. At the five-year follow up, we did not find any infection, graft failure or loosening of implant, in spite of using two massive structural allografts in a single revision total knee arthroplasty.     

Revision unikondylärer Knieprothesen

Despite the good midterm survivorship reported for unicondylar knee arthroplasty, an increase in revision surgery has to be expected due to increased replacement rates. The reasons for failure as well as distribution are different for unicondylar knee arthroplasty compared to total knee arthroplasty. The main reasons for revision are aseptic loosening and the progression of osteoarthritis. In most cases, unicondylar knee arthroplasty will be revised to total knee arthroplasty. To obtain good revision results, the cause of implant failure has to be analysed carefully. In the case of contained bone defects, the reconstruction can be supported with bone grafting. For those cases with uncontained defects, implants with augmentation and, in some cases, stem extensions are needed. The modularity of the revision implant should cover different intraoperative requirements.     

Modular revision systems in total knee arthroplasty. Possibilities and techniques

This paper deals with surgical techniques in revision total knee arthroplasty. The principles of exploring the knee joint, removing the implant, and implanting modular revision systems using a three-step technique are described. The opportunities of modern revision systems for reconstruction of bone defects and ligament instabilities are demonstrated. By means of modularity, the implant can be adapted to individual specifications for bone quality, bone defects, and soft tissue conditions. Modular stems allow an additional diaphyseal load transfer. Uncontained bone defects are reconstructed by metal wedges and blocks. By using the range from cruciate-retaining to condylar-constrained systems, the different degrees of instability can be substituted with the least constrained prosthesis. Totally constrained hinge knee prostheses should be used only in extreme cases such as complete loss of collateral ligaments or inability to correct flexion-extension gap mismatches. The results with modular revision systems described in the literature are reviewed.     

Distal femoral allograft reconstruction for massive osteolytic bone loss in revision total knee arthroplasty

Massive osteolytic bone loss in revision total knee arthroplasty has been an uncommon challenge. From 2001 to 2002, 11 knees in 10 patients underwent revision of failed modular PFC (Johnson and Johnson Orthopaedics, Raynham, Mass) total knee arthroplasties with distal femoral allografts and long-stemmed revision implants for massive osteolytic induced femoral bone loss. The mean follow-up was 42 months (range, 36-48 months). Radiographic graft incorporation was demonstrated in all 11 knees with no cases of loosening. The Knee Society Pain Scores improved by an average of 25.4 points, and the function scores improved by an average of 23.3 points. The outcomes of distal femoral allografts in the reconstruction of massive osteolytic bone loss associated with failed modular PFC (Johnson and Johnson Orthopaedics) total knee arthroplasties are favorable.     

结构性植骨修复膝关节翻修术中严重骨缺损的临床效果及相关分析

目的探讨同种异体结构性植骨在膝关节翻修术中大块骨缺损中应用的临床效果和意义。方法1994～2001年芬兰坦佩雷大学医院应用单一翻修假体及同种异体骨结构性植骨治疗膝关节置换术大块骨缺损患者10例（膝）,男1例,女9例,平均年龄70岁（61—77岁）,平均随访5年（1～8年）,所有手术均由两名高年资专科医师执行,采取KSS评分评估术前术后膝关节功能。结果最后随访时,患者膝关节KSS评分由术前的平均39分（4～51分）提高至81分（28—102分;P〈0．05）;疼痛评分由术前的18分（0—30分）提高至42分（10—50分;P〈0．05）。2例出现假体周围透亮线（〈1mm）,但没有任何松动症状;所有结构性植骨均获得满意的愈合,最后随访时没有出现吸收征象,1例患者术后出现膝前疼痛,经髌骨表面置换后症状消失。结论同种异体骨结构性植骨应用在膝关节翻修术中大块骨缺损中可取得满意的临床效果,重建下肢力线、第三代骨水泥技术的应用及有由专科医师实施手术是获得良好临床效果的保证。     

Contemporary bone loss options: Rebuild,reinforce, and augment

Bone loss is commonly encountered during revision total knee arthroplasty (TKA). Small defects can be adequately managed with cement filling (with or without screws), modular prosthetic augments, and morselized allograft. For larger defects, cancellous impaction grafting and structural allografts have traditionally been utilized. More recently, highly porous tantalum cones and titanium sleeves have been designed to achieve axial and rotational stability in the metaphysis and subsequent biologic fixation. Sleeves are linked to one type of prosthesis, whereas cones are unlinked and can be used with any implant design. Multiple studies have demonstrated excellent survivorship and radiographic osseointegration at mid-term follow-up. This article provides a review of contemporary methods of bone loss management with a focus on highly porous metals and an emphasis on the authors’ preferred method for managing the severe bone loss in revision TKA.     

Einsatz eines modularen Knierevisionssystems MML im Rahmen des Knieprothesenwechsels und der Tumorendoprothetik

Increasing age and a higher level of mobility lead to an increasing incidence in revision arthroplasty after total knee replacement and tumor surgery. So far, the reconstruction of large defects in bony and soft tissue environments can be accomplished by the modern modular components of revision implants. The consecutive reconstruction of the extensor mechanism in extended revision has its own drawbacks and is often associated with significant functional limitations for the patient. Specially designed implants and methods are required to generate good functional results. The modular knee revision system MML provides specific modifications of the tibial component for reconstruction of the extensor mechanism. Combined with artificial strips, an excellent functional outcome could be achieved. In this study, 70 patients were operated with the MML endoprosthesis in knee revision or tumor surgery. An excellent functional outcome could be determined. At 7 years after surgery, an average of 32+/-13 points was achieved on the Oxford Knee Score. The outcome measurement using the functional scoring system of the American Knee Society (AKS score) showed similarly good results with 71+/-25 points out of 100. A minor deficit of only 2 degrees in active extension could be observed after reconstruction of the extensor mechanism. In conclusion, we have demonstrated that the MML modular revision system is appropriate for reconstruction of segmental bone defects.     

Strukturelle Femurkopfallografts in der Revisionschirugie von gelockerten Hüftendoprothesenpfannen

BACKGROUND: Treatment of acetabular bone defects presents a great challenge in revision total hip arthroplasty (THA). Many methods of acetabular reconstruction have been described. The purpose of this study was to evaluate the midterm results of structural femoral head allografts for acetabular reconstruction. METHODS: Thirty-six patients (33 females and 3 males) with acetabular defects ranging from type 2C to type 3B according to Paprosky's classification were included in the study. In all cases acetabular defects were closed using allografts from femoral heads. In 13 cases an uncemented press-fit cup, in 17 cases a cemented polyethylene socket, and in 6 cases a Burch-Schneider antiprotrusion cage was implanted. The mean follow-up period was 84.2 months (range: 5-147). RESULTS: Four acetabular components failed. All 36 grafts were osseointegrated radiographically and formed a mechanically stable construction. The mean Harris Hip Score at the most recent follow-up was 79.8 points. The distance from the obturator line to the prosthesis head center was 3.73 cm (1.17-5.80 cm) preoperatively and 2.79 cm (0.85-4.8 cm) postoperatively (p<0.05). The distance from the teardrop figure to the prosthesis head center was 3.02 cm (1.0-5.8 cm) preoperatively and 3.25 cm (1.6-4.8 cm) postoperatively (p<0.001). CONCLUSIONS: Closure of acetabular defects of types 2C to 3B according to Paprosky's classification can be satisfactorily accomplished using femoral head allografts. These allografts may facilitate future revision surgery. Femoral heads are readily available due to widespread primary total hip replacement surgery. However, the use of structural femoral head allografts for acetabular reconstruction is cost intensive. Individual patient-related aspects, such as the function of revision arthroplasty, have to be considered when planning revision arthroplasty using femoral head allografts.     

Bone loss following knee arthroplasty: potential treatment options

Introduction

The management of bone loss is a crucial aspect of the revision knee arthroplasty. Bone loss can hinder the correct positioning and alignment of the prosthetic components, and can prevent the achievement of a stable bone–implant interface. There is still controversy regarding the optimal management of knee periprosthetic bone loss, especially in large defects for which structural grafts, metal or tantalum augments, tantalum cones, porous metaphyseal sleeves, and special prostheses have been advocated. The aim of this review was to analyze all possible causes of bone loss and the most advanced strategies for managing bony deficiency within the knee joint reconstruction.

Materials and methods

Most significant and recent papers about the management of bone defects during revision knee arthroplasty were carefully analyzed and reviewed to report the most common causes of bone loss and the most effective strategies to manage them.

Results

Modular metal and tantalum augmentation showed to provide more stable and durable knee revisions compared to allografts, limited by complications such as graft failure, fracture and resorption. Moreover, modular augmentation may considerably shorten operative times with a potential decrease of complications, above all infection which has been frequently associated to the use of allografts.

Conclusions

Modular augmentation may significantly reduce the need for allografting, whose complications appear to limit the long-term success of knee revisions.     

Revision of failed acetabular cups with extensive structural allografts

AIM: Structural allografts are used with encouraging results for revision of failed total hip arthroplasty and in the surgery of bone tumours. The aim of the present study is to describe the clinical and radiological results achieved with structural allografts in revision of a total hip arthroplasty. MATERIAL AND METHODS: 15 patients (12 female and 3 male patients) were revised with an acetabular defect situation of type 3 A or 3 B according to the Paprosky classification. Five fresh-frozen acetabula, nine distal femora and one proximal tibia were used for acetabular reconstruction. The rigid graft fixation was performed with 2 > or = AO screws. In one case a cemented acetabular ring was implanted, four cementless cups and ten cemented polyethylene acetabular components were used. The mean follow-up was 7.9 years (1.6-11.0 years). RESULTS: A stable osseointegration of fifteen transplanted structural allografts was achieved in thirteen cases. Two allografts (one aseptic loosening, one deep infection) failed to osseointegrate. In one case the migration of a cementless cup was registered. Revision surgery of this female patient was performed successfully with a cemented reconstruction ring. The mean Harris hip score at the latest follow-up was 81.4 points (70-99 points). CONCLUSION: For reconstruction of acetabular bone stock and restoration of the bone anatomy structural allografts can be recommended. The use of cementless cups in combination with structural grafts is to be evaluated as critical.     

Review article: Treatments for bone loss in revision total knee arthroplasty

Bone deficiency hinders implant alignment and stabilisation of the bone-implant interface in revision total knee arthroplasty (TKA). Treatments for bone defects include bone cement, bone cement with screw reinforcement, metal augments, impaction bone grafts, structural allografts, and tantalum, depending on the location and size of the defects. Small defects are usually treated with cement, cement plus screws, or impaction allograft bone. Large defects are repaired with structural allografts or metal augments. Recent developments involve the use of highly porous osteoconductive tantalum. We reviewed the pros and cons of each method for bone defect management in revision TKA.     

The use of bulk allografts in revision knee arthroplasty

During the revision of a failed total knee implant, when large osseous defects are encountered, the surgeon has the following three options for managing severe bone loss: revision with a custom implant, revision with a rotating-hinge component, or reconstruction with an allograft and a long-stemmed revision component. An allograft reconstruction replaces the damaged bone, albeit with dead bone; whereas the other two options require additional bone to be removed. By using a bone defect classification system preoperatively, the surgeon estimates the extent of bone damage and orders the proper revision system and allograft material. A durable revision arthroplasty is achieved by using long-stemmed implants that provide axial stability, cementless stems that permit compressive loads, and step cuts that achieve rotational stability.     

Conversion of failed modern unicompartmental arthroplasty to total knee arthroplasty

Between January 1983 and January 1991, 29 patients (31 knees) with a failed Robert Brigham metal-backed knee arthroplasty (Johnson & Johnson, Raynham, MA) underwent revision to a total knee arthroplasty (TKA). Twenty-five patients had osteoarthritis, three avascular necrosis, and one rheumatoid arthritis. The average patient age was 72.3 years (range, 49–88 years), and the average weight was 179 lb. (range, 112–242 lb.). The interval between the primary and secondary index procedures averaged 62 months (range, 7–106 months), and mean postrevision follow-up period was 45 months (range, 24–104 months). The primary mechanism of failure of the UKA was tibial polyethylene wear in 21 knees and opposite compartment progression of arthritis in 10 knees. Sixteen knees had particulate synovitis with dense metallic staining of the synovium. At revision, the posterior cruciate ligament was spared in 30 knees and substituted in 1 knee. Restoration of bony deficiency at revision required cancellous bone—graft for contained defects in seven knees, tibial wedges in four knees, and femoral wedges in two knees. No defects received structural allografts. The data suggest that failed, modern unicompartmental knee arthroplasty can successfully be converted to TKA. In most cases, the posterior cruciate ligament can be spared and bone defects corrected with simple wedges or cancellous grafts. Moreover, the results of revision of failed unicompartmental knee arthroplasty are superior to those of failed TKA and failed high tibial osteotomy and comparable to the authors' results of primary TKA with similar-length follow-up periods. Although these results are encouraging, longer-term follow-up evaluation is required to determine survivorship of these revision arthroplasties.     

Reconstruction of the failed femoral component and proximal femoral bone loss in revision hip surgery

Advances in implant technology and surgical techniques have greatly improved the results of femoral stem revision in total hip arthroplasty. The 10-year results obtained with extensively coated noncemented revision stems parallel those obtained with cemented stems revised by using contemporary techniques. Proximal femoral bone loss is an important consideration when planning and performing revision arthroplasty. Proximal femoral bone defects can be managed with either metal or bone. Insignificant defects can be reconstructed by using primary hip arthroplasty techniques. Proximal femoral replacement prostheses are best restricted to sedentary elderly patients. Cortical strut grafts can be used reliably to reconstruct noncircumferential segmental defects. Calcar allografts are associated with unacceptably high rates of resorption. Proximal femoral allografts with either noncemented or cemented long-stem prostheses have the potential advantage of biologic soft-tissue attachment and restoration of bone stock. Impaction allografting with cement is indicated for cavitary defects and may also restore bone stock.     

Selection of bone grafts for revision total hip arthroplasty

The selection of bone grafts to reconstruct deficient bone for revision hip replacement requires an understanding of specific bone graft functions and the critical steps of the biologic incorporation of the graft into the host. Bone grafts provide functions of osteogenesis, either graft derived or by osteoinduction, osteoconduction, or both, and mechanical support. Autologous cancellous bone provides excellent osteogenesis and osteoconduction without structural support. Nonvascularized cortical autografts provide mechanical support and are somewhat osteogenic. Allogeneic cancellous bone is osteoconductive and minimally osteoinductive, whereas cortical allografts provide structural support, if not freeze-dried, and are somewhat osteoconductive. Allogeneic demineralization bone matrix is highly osteoinductive. The selection of the appropriate bone graft depends on the classification of the bone deficiency. Cavitary (contained) defects can be reconstructed with cancellous morselized autograft, frozen or freeze-dried allograft, or allogeneic demineralized bone matrix. Segmental defects require bulk corticocancellous and/or cortical autografts or allografts. The ultimate incorporation of the bone graft depends on the interaction of the graft and the host's mechanical and biologic environment, and host-bone graft contact and stability. Optimum bone graft selection will enhance the clinical outcomes in revision total hip arthroplasty.     

The use of porous metal cones in revision total knee arthroplasty

Massive bone defects represent a major problem in revision total knee arthroplasty. Traditionally, structural allograft has been used for this purpose; however, this is technically demanding and is associated with a failure rate. Metaphyseal tantalum cones have been a major advancement. They have made surgery easier and have yielded better results when compared to reconstruction with allograft. Adding the ability to comfortably use these implants to one’s armamentarium should be a priority for surgeons who regularly revise total knee replacements. These implants have completely replaced the use of structural allografts in the authors’ practice.     

6 years follow-up of hip revision surgery

Revision total hip arthroplasty often presents surgeons with difficult bone loss problems. The purpose of this study was to evaluate the results of hip revision surgery according to bone stock We evaluated, in a retrospective study, 148 hip revision surgeries during 2004 to 2010. The Harris Hip Score (HHS), the acetabular cementation, the AAOS classification, the SOFCOT 99 bone loss grading and Barrack classification were used for clinical and radiological assessment. It can be observed significant improvement of HHS from a mean value of 45 preoperatively to 77.2 points postoperatively. Grade B acetabular cementation was observed in a significantly higher rate for situations that needed acetabular allograft reconstruction and where it cannot be performed because of allografts lack. Barrack grades C and D cementation were associated with 70% of SOFCOT 99 stage III and IV cases and only 5% of SOFCOT 99 stage 0-II cases.Using bone graft seems to be a reliable solution for restoring bone stock and stabilizing the cup in revision total hip arthroplasty with type II-IV acetabular defect according to the AAOS classification. Because SOFCOT 99 stages III-IV are often associated with poor cementation we prefer using uncemented distally fixed with screws revision stems for these cases.     

Stellenwert der Revisions- und Tumorendoprothetik bei der Versorgung periprothetischer Frakturen der unteren Extremität

Periprosthetic fractures of hip and knee prostheses are gaining clinical significance due to the increasing numbers of of primary arthroplasties. Additionally, these fractures are often associated with poor bone quality or present in patients after multiple revision procedures and concomitant excessive bone defects precluding those patients to be adequately treated by conventional osteosynthesis. Revision implants provide a wide range of options for the treatment of these fractures in order to achieve good clinical results. In the acetabular region cavitary defects associated with periprosthetic fractures can be treated by the use of megacups. Extensive segmental defects and pelvic discontinuity necessitate the use of cups with additional iliac support or even customized implants. Proximal femoral fractures can usually be fixed with modular stems and diaphyseal anchorage. Periprosthetic knee joint fractures can be treated with revision implants with modular sleeves or augment-combinations allowing sufficient bridging of bony defects. Functional reconstruction or refixation of the extensor mechanism is of crucial importance.     

Etiology of early loosening after aseptic cup replacement using allogenic bone blocks and cement-free press-fit cups

PURPOSE: There are two problems using structural allografts in revision total hip surgery. The long-term stability of bulk allografts and the intraoperative primary stability of the graft and implant limit the success of this revision philosophy. The purpose of this study was to analyse the reasons of early loosening of cementless cups after reconstruction with bulk allografts. METHOD: In a retrospective study 78 revisions were analysed radiologically. The preoperative stage of bone destruction, the size of allografts, the implant-allograft coverage, and the position of implants were analysed in X-ray series. RESULT: There were 12 (15.3%) cases with aseptic and 5 (6%) cases with septic cup loosening, after revision surgery, with an average follow-up of 37 (25-84) months. All of these failures were registered in the first 12 months postoperatively. Large bone defects and an implant-allograft coverage of more than 50% are significant (p < 0.001) risk factors of early aseptic loosening. CONCLUSIONS: It is important to give careful attentions to primary stability, especially in revision total hip arthroplasty using structural allografts and cementless cups. For primary stability as well as secondary stability a stable fixation with as large as possible areas of contact between implant and living bone is necessary. The limit of the method (allograft and cementless cup) is to be seen in stage 2B according Paprosky (1990). In larger defects alternative reconstruction methods have to be used.     

Filling of segmental bone defects in revision knee arthroplasty using morsellized bone grafts contained within a metal mesh

For revision knee surgery with uncontained tibial bone defects, the authors report the containment of compacted morsellized allograft using metal-wire mesh, followed by implantation of a cemented total knee prosthesis. This method is comparable to the "impaction grafting technique" described for revision hip surgery and could be an alternative to metal wedges, augmented components, custom-made implants, polymethyl-methacrylate or structural bone grafts to solve some problems of cavitary and segmental bone defects in revision total knee arthroplasty.