Purpose. Cementless cup with structural allograft is one of option for acetabular revision in the cases which has severe bone loss. This study was performed to verify that the structural allograft with cementless cup could be one of good options for revision of acetabular cup with severe bone defect and to verify that the allograft resorption affect the stability of cementless acetabular cup. Materials and Methods. We reviewed 25 cases of 25 patients who underwent acetabular cup rvision using cementless porous coated hemispherical cup with structural allograft from May 1992 to July 2011 July 2011. There were nine males and sixteen females with an average age of 50.0 years. The average follow-up period was 76.7(28∼212) months. The clinical evaluation was performed using Harris Hip Score(HHS) and UCLA activity score. Radiologically, the degree of resorption of grafted bone, incorporation of allograft bone with normal bone, osteolysis and cup loosening were evaluated. Results. Clinically, the average Harris hip score was improved from 54 preoperatively to 93.4 at the last follow-up. The average UCLA activity score was also improved from 4.3 preoperatively to 6.4 at the last follow-up. Radiologically, the incorporation of allograft was accomplished in 11.4 months and the resorption of grafted bone was noted in 3 cases(12%), but the allograft resorption had not progressed to moderate degree even in long term follow-up. There was no cup loosening and average survivor rate was 100% in 6 years. There was no infection, allograft nonunion, osteolysis. Conclusion. Cementless cup with structural allograft in acetabular cup reconstruction can provide excellent mi-term results in both clinical and radiological aspects. Structural allograft can provide strong mechanical support for the bone ingrowth of cementless cup. The clinical result of this study auggest that cementless cup with structural allograft can be a good option for acetabular cup revision with severe bone defect. Resorption of structural allograft rarely occurred, and the resorption of structural allograft does not affect stablility of cup even in long term follow-up

Acetabular bone defects are common in revision total hip arthroplasty and are usually worse than depicted on routine radiographs. These defects may be cavitary, segmental or both. For cavitary and segmental defects with more than 50% host support, our preference is to use a cementless revision acetabular component, supplemented by the use of screw fixation and morselised bone graft. For cavitary and segmental defects with less than 50% host support, the use of an anti-protrusio cage, morselised bone graft and a cemented all polyethylene socket is preferred. Our use of structural allografts is much less common. Indications would include absence of the acetabular dome or posterior column. Our preferred technique is use of the “reverse 7” distal femoral allograft. Whenever a structural allograft is used, we would reinforce this with the use of an anti-protrusio cage. This approach has yielded predictable excellent clinical results

Bone loss options in revision total knee replacement include prevention (earlier revision before extensive osteolysis, tedious prosthesis removal), prosthetic substitution, and bone grafting. Massive bone loss options include arthrodesis, custom total knee replacement, amputation, or revision with structural allograft-prosthesis composites. Advantages of structural allografts include their biologic potential, versatility (shape to fit host defects), relative cost effectiveness, potential for bone stock restoration, and the potential for ligamentous reattachment. Potential disadvantages include the risk of disease transmission and graft nonunion, malunion, collapse, or resorption. Extensive preoperative planning is required to rule out infection as well as properly select both the type and size of allograft and prosthetic implant. Fresh frozen allograft specimens are most commonly selected due to superior strength. Implant designs with diaphyseal-engaging stems and increased prosthetic constraint are often required. Extensive surgical exposure is often needed including proximal quadricepsplasty or tibial tubercle osteotomy in some cases. Both the host site and allograft require meticulous preparation both to maximise surface contact between host and allograft as well as mechanical interlock of the allograft with the host. Allograft fixation must be rigid to allow for incorporation. Diaphyseal-engaging stems, screws, and/or plates are often required to obtain this. The favoured method of fixation is cementing the prosthesis to the allograft with the addition of diaphyseal- engaging stems into the host medullary canal. Equivalent results have been obtained with either cemented or press-fit stems. Ligamentous reattachment to the allograft is more successful when done via a bone block technique. Wound closure difficulties may be encountered, particularly in the tibial region. Relaxing incision techniques as well as rotational muscle flaps are occasionally necessary to obtain soft tissue closure without excessive tension. Short-term results have shown union rates at greater than 90% when rigid fixation is obtained. In the author’s series of 32 cases, 86% good to excellent results were obtained at an average follow- up period of 50 months. More common complications include instability and graft collapse. Use of more constrained prostheses with long intramedullary stems will lessen these complications

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

In this report, porous tantalum was used to achieve abductor tendon reattachment to structural allograft of the proximal femur in salvage reconstruction of a failed total hip arthroplasty. In each case, a porous tantalum segment with trapezoidal cross section was fixed to a dovetail joint of complementary geometry cut into the lateral greater trochanter. Fixation of the porous tantalum to the allograft was supplemented with polymethylmethacrylate cement. Residual abductors were mobilized from the surrounding soft tissues and secured against the porous tantalum segment with a short greater trochanteric reattachment device and cables. Patients were followed up at 73 and 80 months. Harris Hip Scores of 74 and 80 respectively were found. Both were unlimited community ambulators without support, had negative Trendelenberg signs, and were satisfied with the clinical outcomes. This preliminary experience suggests that porous tantalum has potential application in cases of severe proximal femoral bone loss involving abductor deficiency

Purpose of the Study: The outcome after revision knee arthroplasty with structural distal femoral allograft augmentation for major bone loss has been rarely reported in the literature. The aim of this study was to assess the outcome for patients managed with such a procedure in our hospital. Materials and Methods: Since 2001, ten revision knee arthroplasties requiring structural distal femoral allograft for major bone loss were performed in nine patients who underwent surgery at mean age of 68.1±9.8 years and prospectively followed. All patients were operated by the same surgical team. The first assessment was completed for the patients during August 2005 for radiographic and clinical evaluation. The mean follow up time was 22.2±15.1 months. Results: On radiographic analysis none of the allografts had resorbtion. Implant position. Was preserved in all patients. Two patients had postoperative complications: one had superficial wound infection without need of surgical revision, another patient needed angioplasty because of pseudoaneurisma of popliteal artery and temporary using of knee brace for mild medial instability. Clinical evaluation revealed that mean “Hospital for Special Surgery Score” had improved from 39.8 to 84.1 points and mean range of motions improved from 75.0±42.0 to 103.5±12.5 (p=0.05, paired t-test). Before the surgery all patients used a walker or a crutch, while only one of them used a cane and the remaining patients walked without any support after the operation. Conclusions: Our preliminary results demonstrate that structural femoral allografts used in revision knee replacement improve clinical and functional outcomes. Further follow-up is planned

Introduction and Objectives: The treatment of choice in periprosthetic Vancouver B1 fractures is open reduction and fixation with an osteosynthesis plate. There is a certain amount of controversy as to the need to also use a cortical allograft plate. Materials and Methods: We carried out a revision of periprosthetic fractures Vancouver type B1 treated with Dall-Milles (Styker) plates with and without an additional cortical allograft. Results: We included a total of 12 patients operated between March 2003 and July 2207, 6 of them had a plate and also an allograft plate (AP) and 6 only had a DM plate alone (DMP). There was one case of superficial infection of the surgical wound in the AP group in the only case of an open fracture (grade 1) in the series. No osteosynthesis failures were seen in either of the groups. Mean age (4 years more), mean hospital stay (4 days more), need for transfusion (33% more) and mortality (16% more) were all greater in the AP group; whereas the size of the DM plate and operation time (30 minutes less) were less. The EQ-5D health scale was one tenth better in the DMP group, but, curiously, the Oxford Hip Score was 9 points lower. Discussion and Conclusions: Not all patients with periprosthetic fractures Vancouver type B1 treated with a DM plate need the addition of a structural allograft plate. We consider that patients with low bone quality and who were functionally independent before fracture are those that will need a cortical allograft

Introduction

Cancellous and cortical bone used as a delivery vehicle for antibiotics. Recent studies with cancellous bone as an antibiotic carrier in vitro and in vivo showed high initial peak concentrations of antibiotics in the surrounding medium. However, high concentrations of antibiotics can substantially reduce osteoblast replication and even cause cell death.

Introduction. Large acetabular bone defects caused by aseptic loosening are common. Reconstruction of large segmental defects can be challenging. Various implants and operative techniques have been developed to allow further acetabular revision in cases where bone stock is poor. Reconstitution of bone stock is desirable especially in younger patients. The aim of the study was to review the clinical and radiological results of hip revision with structural acetabular bone grafts using fresh frozen allograft and cemented components. Method. Between 1990 and 2014, 151 first time revisions for aseptic acetabular loosening with acetabular reconstruction with a fresh frozen structural allograft and cemented components were performed at our hospital. Graft dimensions, number of screws used and socket coverage by the graft were measured on the post-operative AP radiograph. Follow-up radiographs were analysed for socket loosening, quality of graft union, graft and graft resorption. Results. At a mean follow-up of 7 years 11 months (range 0 – 22), 5 patients had died and 24 hips revised (15.9%). One hundred and three hips had a follow-up greater than 5 years. The reasons for re-revision were infection in 1, recurrent dislocation in 4, aseptic stem loosening in 4 and aseptic cup loosening in 21 (13.9%). Survival analysis with revision for aseptic cup loosening as the endpoint was 80.2% at 10 years. Conclusion. The results using solid allograft to reconstruct the acetabulum are encouraging with a follow-up to 22 years. Structural allograft is a good option to reconstruct segmental defects of the acetabulum at revision surgery and we especially advocate its use to reconstitutes bone stock in younger patients

INTRODUCTION. Allograft reconstruction after resection of primary bone sarcomas has a non-union rate of approximately 20%. Achieving a wide surface area of contact between host and allograft bone is one of the most important factors to help reduce the non-union rate. We developed a novel technique of haptic robot-assisted surgery to reconstruct bone defects left after primary bone sarcoma resection with structural allograft. METHODS. Using a sawbone distal femur joint-sparing hemimetaphyseal resection/reconstruction model, an identical bone defect was created in six sawbone distal femur specimens. A tumor-fellowship trained orthopedic surgeon reconstructed the defect using a simulated sawbone allograft femur. First, a standard, ‘all-manual’ technique was used to cut and prepare the allograft to best fit the defect. Then, using an identical sawbone copy of the allograft, the novel haptic-robot technique was used to prepare the allograft to best fit the defect. All specimens were scanned via CT. Using a separately validated technique, the surface area of contact between host and allograft was measured for both (1) the all-manual reconstruction and (2) the robot-assisted reconstruction. All contact surface areas were normalized by dividing absolute contact area by the available surface area on the exposed cut surface of host bone. RESULTS. The mean area of contact between host and allograft bone was 24% (of the available host surface area) for the all-manual group and 76% for the haptic robot-assisted group (p=0.004). CONCLUSIONS. This is the first report to our knowledge of using haptic robot technology to assist in structural bone allograft reconstruction of defects left after primary bone tumor resection. The findings strongly indicate that this technology has the potential to be of substantial clinical benefit. Further studies are warranted

We evaluated the use of a hemipelvic acetabular transplant in twenty revision hip arthroplasties with massive acetabular bone defects (Paprosky IIIB) at a mean follow-up of 5-years (4–10 years). These defects were initially trimmed to as geometric a shape as possible by the surgeon. The hemipelvic allografts were then cut to a geometric shape to match the acetabular defects and to allow tight stable positioning of the graft between the host ilium ischium and pubis. The graft was further stabilised with screw fixation. A cemented cup (without a reinforcement ring) was entirely supported by the allograft in all procedures.

We report 65% good intermediate-term results.

There were seven failures (five aseptic loosening and two deep infections). Radiographic bone bridging between the graft and host was evident in only one of these cases. Aseptic graft osteolysis began radiographically at a mean of 14 months and revision occurred at a mean of 2 years in the 5 aseptic failure cases. All 5 cases could be reconstructed again due to the restoration of bone stock provided by the hemipelvic graft. One infected case was able to be reconstructed using impaction allografting and the other was converted to a Girdlestone hip.

Thirteen of twenty acetabular reconstructions did not require revision. Radiographic bone bridging between the graft and host was evident in 12 cases. In 2 cases, ace-tabular migration began early (at 5 and 27 months) but stopped (at 35 and 55 months). These 2 cases have been followed for 6 and 9 years respectively, with no further migration. Two dislocations occurred but did not require acetabular revision.

The function of these hips is good with a mean Postel Merle D’Aubigne score of 16.5.

We feel that these are satisfactory intermediate term results for massive acetabular defects too large for reconstruction with other standard techniques.

Background. Ankle and hindfoot fusion in the presence of large bony defects represents a challenging problem. Treatment options include acute shortening and fusion or void filling with metal cages or structural allograft, which both have historically low union rates. Impaction grafting is an alternative option. Methods. A 2 centre retrospective review of consecutive series of 32 patients undergoing hindfoot fusions with impaction bone grafting of morselised femoral head allograft to fill large bony void defects was performed. Union was assessed clinically and with either plain radiography or weightbearing CT scanning. Indications included failed total ankle replacement (24 patients), talar osteonecrosis (6 patients) and fracture non-union (2 patients). Mean depth of the defect was 29 ±10.7 mm and mean maximal cross-sectional area was 15.9 ±5.8 cm. 2. Tibiotalocalcaneal (TTC) arthrodesis was performed in 24 patients, ankle arthrodesis in 7 patients and triple arthrodesis in 1 patient. Results. Mean age was 57 years (19–76 years). Mean follow-up of 22.8 ±8.3 months. 22% were smokers. There were 4 tibiotalar non-unions (12.5%), two of which were symptomatic. 10 TTC arthrodesis patients united at the tibiotalar joint but not at the subtalar joint (31.3%), but only two of these were symptomatic. The combined symptomatic non-union rate was 12.5%. Mean time to union was 9.6 ±5.9 months. One subtalar non-union patient underwent re-operation at 78 months post-operatively after failure of metalwork. Two (13%) patients developed a stress fracture above the metalwork that healed with non-operative measures. There was no bone graft collapse with all patients maintaining bone length. Conclusion. Impaction of morselised femoral head allograft can be used to fill large bony voids around the ankle and hindfoot when undertaking arthrodesis, with rapid graft incorporation and no graft collapse despite early loading. This technique offers satisfactory union outcomes without the need for shortening or synthetic cages

Background. Revision total hip arthroplasty (THA) is a challenging scenario following complex primary THA for developmental dysplasia of hip (DDH). This study envisages the long-term outcomes of revision DDH and the role of lateral structural support in socket fixation in these young patients who may require multiple revisions in their life-time. Materials and methods. Hundred and eighteen consecutive cemented revision THAs with minimum follow up of 5 years following primary diagnosis of DDH operated by a single unit between January 1974 and December 2012 were analysed for their clinical and radiological outcomes. Results. The mean follow-up of 118 patients was 11.0 years (5.1–39.6 years). At 11 years, the cumulative survivorship with revision as the endpoint was 89.8%. Amongst the 88 acetabular revisions for aseptic loosening, 21 had pre-existing autologous lateral structural bone graft from the primary THA (group A). Only 3 (14%) of them required lateral structural re-grafting using allograft at revision. With the remaining 18 hips, the lateral support from the previous graft facilitated revision with no requirement of additional structural graft. Sixty-seven hips did not have lateral structural autograft during primary operation (group B). Amongst them, 18 (27%) required lateral structural allograft in revision surgery. Discussion. There is paucity of evidence regarding long-term results following revision THAs in patients with DDH. Nearly double the number of patients with no previous acetabular structural bone graft needed structural allograft during revision in comparison to those patients with autologous structural bone grafting done at primary operation. The lateral structural autograft used at primary arthroplasty seems to provide invaluable bone stock for future revisions. Conclusion. This study reports the largest number of revision THAs with primary diagnosis of DDH with the longest follow up. In our experience, the lateral support from the structural graft done in primary operation appears to have provided benefit in subsequent revision socket fixation

Introduction:. We report the outcomes of salvage procedures in total ankle replacement (TAR) in a single surgeon series. Methods:. This study was a retrospective review of patients who had undergone salvage procedures with tibio-talo-calcaneal (TTC) fusion for failed TAR over a period from 1999–2013 in a single centre. In this period, 317 TAR were performed of which 11 have failed necessitating conversion to TTC fusion. Clinical documentation and radiographs were reviewed for cause of failure, type of graft for fusion, time to radiological/clinical union and complications including further surgeries. Results:. The causes of failure of the TAR were pain from instability/impingement in 8, fracture in one, subsidence of the talar component in one and infection in one. From the group of 11 patients, 8 patients went onto union at a mean of 10 months (7–14). All 8 patients had femoral head structural allografts to maintain limb length for the procedure and 3 required a secondary procedure to dynamise the nail. 2 patients with femoral head structural allografts developed infections necessitating removal of the graft and conversion to an external fixator of which one united and the other developed a painless fibrous union. 1 patient developed non-union with progressive deformity of the ankle resulting in a Symes amputation. Conclusions:. From our series of patients we have demonstrated that failure of TAR requiring salvage procedures is a relatively rare event (3.5%). The use of TTC fusion is successful in the majority of patients and the use of femoral head structural allografts allows preservation of leg length with good rates of union

Massive bone loss on both the femur and tibia during revision total knee arthroplasty (TKA) remains a challenging problem. Multiple solutions have been proposed for small osseous defects, including morselised cancellous bone grafting, small-fragment structural allograft, thicker polyethylene inserts, and the use of modular augments attached to revision prosthetic designs. Large osseous defects can be treated with structural allografts, impaction bone-grafting with or without mesh augmentation, custom prosthetic components, and specialised hinged knee components. The metaphyseal area of the distal femur and proximal tibia is a particularly attractive option during revision TKA given that it is usually undamaged and well-vascularised. While multiple reconstructive options have been recommended, porous tantalum metaphyseal cones have the advantage of improved biologic fixation because of their high porosity (75–80%), interconnected pore space, and low modulus of elasticity (3 MPa) similar to that of cancellous bone. Such features allow tantalum cones to fill bone defects while tolerating physiological loads. Indications for porous tantalum metaphyseal cones include patients with Anderson Orthopaedic Research Institute Type 2B or greater defects. The surgical technique is simpler than structural allograft reconstructions with decreased preparation time, resulting in a possible decrease in infection rates. The modularity of porous tantalum metaphyseal cones also allows the surgeon to choose a size and position that best fits the individual defect encountered. Moreover, tantalum cones can be used with several revision systems. Short-term clinical follow up indicates that porous tantalum metaphyseal cones effectively provide structural support with the potential for long-term biologic fixation and durable reconstructions

The management of bone loss in revision total knee replacement (TKA) remains a challenge. To accomplish the goals of revision TKA, the surgeon needs to choose the appropriate implant design to “fix the problem,” achieve proper component placement and alignment, and obtain robust short- and long-term fixation. Proper identification and classification of the extent of bone loss and deformity will aid in preoperative planning. Extensive bone loss may be due to progressive osteolysis (a mechanism of failure), or as a result of intraoperative component removal. The Anderson Orthopaedic Research Institute (AORI) is a useful classification system that individually describes femoral and tibial defects by the appearance, severity, and location of bone defects. This system provides a guideline to treatment and enables preoperative planning on radiographs. In Type 1 defects, femoral and tibial defects are characterised by minor contained deficiencies at the bone-implant interface. Metaphyseal bone is intact and the integrity of the joint line is not compromised. In this scenario, the best reconstruction option is to increase the thickness of bone resection and to fill the defect with cancellous bone graft or cement. Type 2 defects are characterised by deficient metaphyseal bone involving one or more femoral condyle(s) or tibial plateau(s). The peripheral rim of cortical bone may be intact or partially compromised, and the joint line is abnormal. Reconstruction options for a Type 2A defect include impaction bone grafting, cement, or more commonly, prosthetic augmentation (e.g. sleeves, augments or wedges). In Type 2B defects, metaphyseal bone of both femoral condyles or both tibial plateaus is deficient. The peripheral rim of cortical bone may be intact or partially compromised, and the joint line is abnormal. Options for a Type 2B defect include impaction grafting, bulk structural allograft, prosthetic augmentation, metaphyseal sleeves (in some cases), or metaphyseal cones. Finally, in the presence of a Type 3 deficiency, both metaphyseal and cortical bone is deficient and there is partial or complete disruption of the collateral ligament attachments. In this case, the most commonly used reconstruction options include hinged implants or megaprostheses with or without bulk structural allograft, prosthetic augmentation, and/or metaphyseal/diaphyseal sleeves or cones. Today, we are fortunate to have a wide variety of options available to aid in reconstruction of a revision TKA with massive bone loss. Historically, use of cement, bone grafting, or use of a tumor-type or hinged implant were considered the main options for reconstruction. The development and adoption of highly porous sleeves and cones has given the surgeon a new and potentially more durable option for reconstruction of previously difficult to treat defects. Using radiographs and computed tomography, surgeons are able to preoperatively classify bone loss and anticipate a reconstruction plan based upon the classification; however, it is always important to have several back-up options on hand during revision surgery in the event bone loss is worse than expected

Background. Structural bone allografts are an established treatment method for long-bone structural defects arising from such conditions as trauma, sarcoma, and osteolysis following total joint replacement. However, the quality of structural bone allografts is difficult to non-destructively assess prior to use. The functional lifetime of structural allografts depend on their ability to resist cyclic loading, which can lead to fracture even at stress levels well below the yield strength. Because allograft bone has limited capacity for remodeling, optimizing allograft selection for bone quality could decrease long-term fracture risk. Raman spectroscopy biomarkers can non-destructively assess the three primary components of bone (collagen, mineral, and water), and may predict the resistance of donor bone allografts to fracture from cyclic loads. The purpose of this study was to prospectively assess the ability of Raman biomarkers to predict number of cycles to fracture (“cyclic fatigue life”) of human allograft cortical bone. Methods. Twenty-one cortical bone specimens were from the mid-diaphysis of human donor bone tissue (bilateral femurs from 4 donors: 63M, 61M, 51F, 48F) obtained from the Musculoskeletal Transplant Foundation. Six Raman biomarkers were analyzed: collagen disorganization, type B carbonate substitution (a surrogate for mineral maturation), matrix mineralization, and 3 water compartments. Specimens underwent cyclic fatigue testing under fully reversed conditions at 35 and 45MPa (physiologically relevant stress levels for structural allografts). Specimens were tested to fracture or to 30 million cycles (“run-out”), simulating 15 years of moderate activity (i.e., 6000 steps per day). Multivariate regression analysis was performed using a tobit model (censored linear regression) for prediction of cyclic fatigue life. Specimens were right-censored at 30 million cycles. Results. All of the 6 biomarkers that were evaluated were independently associated with cyclic fatigue life (p < 0.05). The multivariate model explained 70% of the variance in cyclic fatigue life (R2=0.695, p<0.001,). Increasing disordered collagen (p<0.001) and loosely collagen-bound water compartments (p<0.001) were associated with decreased cyclic fatigue life. Increasing type B carbonate substitution (p<0.001), matrix mineralization (p<0.001), tightly collagen-bound water (p<0.001), and mineral-bound water (p=0.002) were associated with increased cyclic fatigue life. In the predictive model, 42% of variance in cyclic fatigue life was attributable to degree of collagen disorder, all bound water compartments accounted for 6%, and age and sex accounted for 17%. Conclusions. Raman biomarkers of three bone components (collagen, mineral, and water) predict cyclic fatigue life of human cortical bone. Increased baseline collagen disorder was associated with decreased cyclic fatigue life, and was the strongest determinant of cyclic fatigue life. Increased matrix mineralization and mineral maturation were associated with increased cyclic fatigue life. Bound-water compartments of bone contributed minimally to cyclic fatigue life. These results are complementary with prior Raman studies of monotonic testing of bone that reported decreased toughness and strength with increased collagen disorder and increased stiffness with increased bone mineralization and mineral maturation. This model should be prospectively validated. Raman analysis is a promising tool for the non-destructive evaluation of structural bone allograft quality and may be useful as a screening tool for selection of allograft bone. Acknowledgements. Supported by a grant from the Musculoskeletal Transplant Foundation. The Dudley P. Allen Fellowship (JYD), Wilbert J. Austin Professor of Engineering Chair (CMR) and the Leonard Case Jr. Professor of Engineering Chair (OA) are gratefully acknowledged

The moderator will lead a structured panel discussion that explores how to manage challenges commonly found in the multiply revised knee. Topics covered will include: (1) Exposure in the multiply operated knee (when to use quad snip, tibial tubercle osteotomy, other techniques); (2) Implant removal: Tips for removing stemmed implants; (3) Management of bone loss in multiply operated knees (metal cones/sleeves vs. structural allograft vs. particulate graft); (4) Level of constraint (when to use posterior stabilised, constrained condylar, and hinge) and management of instability in multiply operated knees; (3) Management of bone loss in multiply operated knees (metal cones/sleeves vs. structural allograft vs. particulate graft); (5) Preferred management of infection in the multiply operated knee; (6) The extensor mechanism: Preferred deficient patellar bone management; Preferred extensor mechanism deficiency management; (7) When is it time to convert to a salvage procedure (i.e. fusion, resection arthroplasty, amputation)?; (8) Post-operative management: wound management; knee range of motion

Metaphyseal bone loss, due to loosening, osteolysis or infection, is common with revision total knee arthroplasty (TKA). Small defects can be treated with screws and cement, bone graft, and non-porous metal wedges or blocks. Large defects can be treated with bulk structural allograft, impaction grafting, or highly porous metal cones. The AORI classification of bone loss in revision TKA is very helpful with pre-operative planning. Type 1 defects do not require augments or graft—use revision components with stems. Type 2A defects should be treated with non-porous metal wedges or blocks. Type 2B and 3 defects require a bulk structural allograft or porous metal cone. Highly-porous metal metaphyseal cones are a unique solution for large bone defects. Both femoral (full or partial) and tibial (full, stepped, or cone+plate) cones are available. These cones substitute for bone loss, improve metaphyseal fixation, help correct malalignment, restore joint line, and permit use of a short cemented stem. The technique for these cones involve preparing the remaining bone with a high speed burr and rasp, followed by press-fit of the cone into the remaining metaphysis. The interface is sealed with bone graft and putty. The fixation and osteoconductive properties of the outer surface allow ingrowth and biologic fixation. The revision knee component is then implanted, with antibiotic-cement, into the porous cone inner surface, which provides superior fixation compared to cementing into deficient metaphyseal bone. There are several manufacturers that provide porous cones for knee revision, but the tantalum-“trabecular metal” cones have the largest and longest clinical follow-up. The advantages of the trabecular metal cone compared to allograft include: technically easier; biologic fixation; no resorption; and lower risk of infection. The disadvantages include: difficult extraction and intermediate-term follow-up. The author has reported the results of 33 trabecular metal cones (9 femoral, 24 tibial) implanted in 27 revision cases at 2–5.7 years follow-up. One knee (2 cones) was removed for infection. All but one cone showed osseointegration. Multiple other studies have confirmed these results. Trabecular metal cones are now the author's preferred method for the reconstruction of large bone defects in revision TKA

The goals of revision arthroplasty of the hip are to restore the anatomy and achieve stable fixation for new acetabular and femoral components. It is important to restore bone stock, thereby creating an environment for stable fixation for the new components. The bone defects encountered in revision arthroplasty of the hip can be classified either as contained (cavitary) or uncontained (segmental). Contained defects on both the acetabular and femoral sides can be addressed by morselised bone graft that is compacted into the defect. Severe uncontained defects are more of a problem particularly on the acetabular side where bypass fixation such as distal fixation on the femoral side is not really an alternative. Most authors agree that the use of morselised allograft bone for contained defects is the treatment of choice as long as stable fixation of the acetabular component can be achieved and there is a reasonable amount of contact with bleeding host bone for eventual ingrowth and stabilisation of the cup. On the femoral side, contained defects can be addressed with impaction grafting for very young patients or bypass fixation in the diaphysis of the femur using more extensively coated femoral components or taper devices. Segmental defects on the acetabular side have been addressed with structural allografts for the past 15 to 20 years. These are indicated in younger individuals with Type 3A defects. Structural grafts are unsuccessful in Type 3B defects. Alternatives to the structural allografts are now being utilised with shorter but encouraging results in most multiply operated hips with bone loss. New porous metals such as trabecular metal (tantalum), which has a high porosity similar to trabecular bone and also has a high coefficient of friction, provide excellent initial stability. The porosity provides a very favorable environment for bone ingrowth and bone graft remodeling. Porous metal acetabular components are now more commonly used when there is limited contact with bleeding host bone. Porous metal augments of all sizes are being used instead of structural allografts in most situations. On the femoral side, metaphyseal bone loss, whether contained or uncontained, is most often addressed by diaphyseal fixation with long porous or tapered implants, modular if necessary. Distal fixation requires at least 4 centimeters of diaphyseal bone and in Type IV femurs, a choice must be made between a mega prosthesis or a proximal femoral allograft. The proximal femoral allograft can restore bone stock for future surgery in younger patients. The mega prosthesis which is more appropriate in the older population may require total femoral replacement if there is not enough diaphyseal bone for distal fixation with cement. Cortical struts are used for circumferential diaphyseal bone defects to stabilise proximal femoral allografts, to bypass stress risers and to serve as a biological plate for stabilising peri-prosthetic fractures