Metaphyseal Cones Research Articles

Management of Bone Defects in Revision Total Knee Arthroplasty with Use of a Stepped, Porous-Coated Metaphyseal Sleeve.

Revision total knee arthroplasty is a costly operation associated with many challenges including bone loss in the distal end of the femur and proximal end of the tibia1,2. Reconstruction of bone defects remains a difficult problem that may require more extensive reconstruction techniques to restore mechanical stability and ensure long-term fixation. Use of porous-coated metaphyseal sleeves is a modern technique to address bone deficiency in revision total knee arthroplasty3,4. Midterm reports have shown excellent survivorship and osseointegration5-7. The use of a porous-coated metaphyseal sleeve begins with intramedullary canal reaming to determine the diameter of the diaphyseal-engaging stem. Bone loss is assessed followed by broaching of the tibial and/or femoral metaphyses. Broaching continues until axial and rotational stability are achieved. The sleeve typically occupies most, if not all, of the proximal tibial and distal femoral cavitary osseous defects often encountered during revision total knee arthroplasty. However, a sleeve does not address all distal and posterior femoral condylar bone loss, for which augments are often required. Previously described methods to address various bone deficiencies include use of morselized or structural bone-grafting, reinforcing screws within cement, metal augments, and metaphyseal cone fixation8-17. Structural allografts or metal augments remain a suitable option for uncontained metaphyseal defects. Metaphyseal structural allografts may undergo stress-shielding, resorption, and late fracture. Metaphyseal sleeves offer long-term biologic fixation to host bone while creating a stable platform to receive a cemented femoral and/or tibial component7. This hybrid combination may provide mechanically protective properties to decrease the loads at the cement-bone interfaces and enhance loads to metaphyseal bone to ensure long-term implant fixation in the setting of substantial bone deficiencies18-20.

Metaphyseal Fixation Using Highly Porous Cones in Revision Total Knee Arthroplasty: Minimum Two Year Follow Up Study

BackgroundHighly porous metaphyseal cones have been introduced to restore metaphyseal integrity for improved cement interdigitation to achieve durable fixation in revision total knee arthroplasty (TKA). The purpose of this study is to review the survivorship, clinical results, and complications of revision TKA using highly porous 3-dimensionally printed titanium metaphyseal cones. MethodsThis is a review of 62 revision TKAs using metaphyseal tibial cones, with 15 cases utilizing both tibial and femoral cones. The mean age of the patients was 66 years (range 32-84) who had a mean follow-up of 27 months (range 24-34). There were 38 women and 24 men, who had a mean body mass index of 33 (range 18.3-62). ResultsRevision-free survival of the cones was 90.2%. If infection was excluded, survivorship was 100%. There were no cases of aseptic loosening. The mean Knee Society Score improved from 51 points preoperatively to 80 points at the time of latest follow-up. The mean Knee Society Functional Score improved from 48 points preoperatively to 68 points. A total of 15 of the 62 patients (24%) required additional surgery: 10 (16%) for infection, 3 (5%) for contracture, 1 for patellar subluxation, and 1 for quadriceps tendon rupture. ConclusionMetaphyseal fixation is important for survivorship in revision TKA which can be challenging due to cancellous and structural bone loss encountered at the time of revision. Prosthetic joint infection continues to be the leading cause of failure in revision TKA. The use of highly porous titanium metaphyseal cones produced from 3-dimensionally printed technology used in this study demonstrated excellent short-term results with no cases of aseptic loosening. Further follow-up is required to determine if these results can be durable over a longer period.

Metaphyseal cones and sleeves in revision total knee arthroplasty: Two sides of the same coin? Complications, clinical and radiological results-a systematic review of the literature.

Revision total knee arthroplasty (rTKA) is increasing of relevance in orthopaedic surgeon daily practice and this trend is likely to continue in the years ahead. The aim of this systematic review of English literature is to summarize and compare indications, complications, clinical and radiological results of metaphyseal cones and sleeves in management of bone loss in rTKA. Retrospective or prospective studies with at least 1year of follow-up (FU) were included. The PRISMA 2009 flowchart and checklist were considered to edit the review. Clinical and radiological results, rates of intraoperative fractures, aseptic loosening, periprosthetic joint infection, septic failure, reoperations and re-revisions were extrapolated by the papers. Thirty-seven articles were included in the systematic review. Results of 927 cones (mean FU of 3.6 ± 1.4years) and 1801 sleeves (mean FU of 4.5 ± 1.6years) were analysed. The studies showed good clinical and functional outcomes. Cones and sleeves allowed a stable metaphyseal fixation. The aseptic survivorship of the implants was 97.3% in cones group and 97.8% in sleeves group. Metaphyseal cones and sleeves represent a viable option in management of type IIb and III AORI bone defects in aseptic and septic TKAr with overlapping survival rate. Further high-quality long-term studies would better clarify complications, clinical and radiological results of these promising techniques in revision total knee arthroplasty.

Addressing large tibial osseous defects in primary total knee arthroplasty using porous tantalum cones

BackgroundTibial osseous defects can present a serious challenge in primary total knee arthroplasty. We describe a technique of using porous tantalum cones along with primary arthroplasty implants to address large tibial osseous defects in primary total knee arthroplasty and present the short-term results. MethodsWe present 17 cases (15 patients) in which primary total knee implants and porous tantalum cones were used to address large tibial bony defects. Clinical results were evaluated using Knee Society Scores, pre- and postoperative knee range of motion, and serial radiographs. ResultsAt an average of 3.5 years of follow-up, all 17 knees had functioning implants with stable metaphyseal cones demonstrating radiographic evidence of osteointegration. At a minimum follow-up of two years, no patient had signs of osteolysis, instability, infection, or systemic complications. All 15 patients had excellent results with an average post-operative Knee Society Score of 94.6. Knee flexion improved by an average of 12.0° and knee extension improved to neutral in all patients. ConclusionPrimary total knee arthroplasty with porous tantalum cone augmentation produced excellent short-term results and should be considered an effective method for addressing large tibial osseous defects in primary total knee arthroplasty.

The Use of Tantalum Metaphyseal Cones for the Management of Severe Bone Defects in Septic Knee Revision

BackgroundFemoral and tibial massive bone defects are common findings in septic total knee revision and pose considerable challenges for the orthopedic surgeon. The aim of this study was to report the midterm clinical and radiographic outcomes with the use of tantalum cones for the management of massive bone defects after 2-stage knee revision. MethodsWe retrospectively reviewed the medical records of 60 patients (mean age, 67.9 ± 8.8 years) treated with 94 tantalum cones associated with constrained or semiconstrained knee for massive bone loss (mean follow-up, 43.5 ± 17.4 months). In all cases, the indication was a staged revision for periprosthetic knee infection. Functional scores, radiographic outcomes, and implant survivorship were analyzed. ResultsThe mean Knee Society Score and Oxford Knee Score improved from 44.1 ± 7.4 and 19.2 ± 4.1 to 85.4 ± 5.6 and 38.4 ± 3.9 (P < .01), respectively. The mean flexion increased from 60.6° ± 15.5° to 96.8° ± 10.9° at the last evaluation (P < .01). The mean improvement in flexion contracture was 6.2 ± 8.0 (P < .01). Two failures (3.3%) due to periprosthetic knee infection recurrence were observed, but no cone-related mechanical failures were reported. The cone-related survival rate was 97.8%. ConclusionExcellent clinical and radiographic midterm outcomes were achieved with a low complication rate. Tantalum cones may be considered a safe and effective option in the management of massive bone defects also in septic knee revision surgery.

Primary Total Knee Arthroplasty in Patients With Neuropathic (Charcot) Arthropathy: Contemporary Results

BackgroundTotal knee arthroplasty (TKA) for neuropathic (Charcot) arthropathy is technically challenging with higher complication rates than primary TKA for osteoarthritis. There is a paucity of data regarding outcomes of TKA in contemporary cohorts with modern implants, techniques, and indications. Our study aimed to determine the (1) survivorship of implants, (2) rates and types of complications, (3) clinical outcomes, and (4) radiographic outcomes in patients treated with primary TKA for Charcot arthropathy. MethodsTwenty-seven patients undergoing 37 TKAs for Charcot arthropathy from 2000 to 2015 were retrospectively reviewed. Mean patient age and follow-up were 60 years and 6 years, respectively. Eighty-one percent were treated with either a varus-valgus constrained or rotating-hinge device, and 81% had supplemental stem fixation. Metaphyseal cones were utilized in 19% of cases. ResultsThe 10-year survivorship free of aseptic revision was 88% and free of any revision was 70%. There were 6 revisions (16%): 4 for infection, 1 for tibial component loosening, and 1 for global instability. There were 3 reoperations (8%). Additional complications occurred in 6 patients (16%) including 3 patients with an intraoperative fracture. Mean Knee Society scores improved from 37 preoperatively to 82 postoperatively (P < .001). There was no radiographic evidence of component loosening in any unrevised knee at latest follow-up. ConclusionsPrimary TKA for Charcot arthropathy with selective use of increased constraint and enhanced metaphyseal component fixation led to significant improvement in pain and clinical outcomes when compared with older techniques; however, there was a high perioperative complication rate. While 10-year survivorship free of aseptic revision was 88%, periprosthetic joint infection led to the poorer survivorship free of any revision of 70% at 10 years. Level of EvidenceLevel IV.

Can tibial tantalum cones eventually eliminate the adjuvant use of metallic augments for AORI type 2B/3 metaphyseal defects??—A novel surgical technique and case series

BackgroundFor extensive metaphyseal defects, the use of tantalum cones is usually combined with adjuvant stems which may be cemented/cementless and metallic bone augments for additional stability. A Tibial baseplate-Cone construct with proud tibial cones and without metallic augments has been described for AORI type 2B/3 tibial defects. MethodsA case series analysis of 6 patients with AORI type 3 defects treated with unstepped proud Tantalum tibial metaphyseal cones without metallic wedges/full width augments. A follow-up analysis done with clinico-radiographic interpretation. Results100% osteointegration noted in final radiographs of all patients at an average follow-up of 4.1 years. Preoperative average ROM/KSS of 75/49 improved to postoperative ROM/KSS of 104/79. Outcomes were interpreted as excellent in 50% of cases and good in the remaining 50%. ConclusionThe “Tibial base plate-cone without augments (BCCA)”type of a construct may offer a valid long term advantage over the Tibial base plate-Augment-Cone combination in massive tibial bone defects. Simply building up the tantalum cone to the native joint line position by increasing cone height can exclude use of augments or wedges.

Do Porous Tantalum Metaphyseal Cones Improve Outcomes in Revision Total Knee Arthroplasty?

BackgroundSome authors have advocated for use of porous tantalum metaphyseal cones to manage bone defects during revision total knee arthroplasty (TKA). The purpose of this study is to compare results with porous metaphyseal cones to results with traditional hybrid stem fixation in revision TKA. MethodsForty-nine patients undergoing revision TKA with femoral and/or tibial metaphyseal cones (39 tibial only, 3 femoral only, 7 both) were matched by surgical indication to 49 patients undergoing revision TKA with a traditional hybrid stem (non-cone) technique. Clinical and radiographic outcomes were compared at a minimum of two-year follow-up (mean 3.5 years) with adjustment for baseline characteristics. ResultsPre-revision bone defects and most baseline demographics were similar between the cone and non-cone cohorts suggesting appropriate matching. Patients in the non-cone cohort had greater pre- to post-operative increases in Knee Society Score (37.2 ± 18.6 vs 28.4 ± 17.8, P = .010) and Knee Society Functional Score (30.4 ± 24.3 vs 13.1 ± 27.6, P = .003). The cohorts did not differ with respect to complications, subsequent reoperation, subsequent revision, patient satisfaction, tibial overhang, the presence of radio-sclerotic lines, cortical hypertrophy around the stems, or tibial subsidence. ConclusionIn this series, metaphyseal cones were not associated with superior outcomes at short-term follow-up. Given the increased cost associated with use of cones compared to traditional techniques, this study cannot support the routine use of metaphyseal cones in revision TKA. Longer-term follow-up will be necessary to determine if construct durability differs over the long term.

Porous Tantalum Femoral Metaphyseal Cones for Large Femoral Bone Defects in Revision Total Knee Arthroplasty.

The use of porous tantalum metaphyseal cones provides reliable metaphyseal support and fixation to help restore the joint line in difficult revision total knee arthroplasties (TKAs) in patients with large femoral bone defects. Adequate preoperative radiographs are important to determine the approximate size of the femoral bone defect prior to surgery. Adequate exposure during revision knee surgery is key for the safe removal of implants and to minimize bone loss. It is essential to disrupt the prosthesis-cement interface before attempting to extract well-fixed components. The first step in revision knee reconstruction is to establish a stable tibial platform. Restoring the joint line and posterior condylar offset are the goals of femoral reconstruction. Thoroughly assess the quality, quantity, and location of the remaining cancellous and cortical bone to determine the proper technique for reconstruction. There are different sizes and shapes of metaphyseal cones that can be used when addressing large femoral bone defects. During the final impaction of the femoral metaphyseal cone, take care to not cause a fracture. Place the final stemmed femoral component through the metaphyseal cone and cement it into place. If a stable construct was achieved, the patient may bear weight as tolerated with no specific restrictions on range of motion. We recently performed a retrospective review of the midterm outcomes at mean of 5 years (range, 2 to 10 years) after 159 consecutive revision TKAs with a porous metal femoral metaphyseal cone in 157 patients with large bone defects 4.

Long-Term Results After Total Knee Arthroplasty with Contemporary Rotating-Hinge Prostheses.

Total knee arthroplasty (TKA) with a rotating-hinge prosthesis is considered a salvage procedure. While excellent immediate stability is achieved, the historically high failure rate has tempered its use. The goal of this study was to determine clinical outcomes, radiographic results, and survivorship after TKA with contemporary rotating-hinge components. We identified 408 consecutive TKAs performed with rotating-hinge components for nononcologic indications from 2002 to 2012 at a single academic institution. Two hundred and sixty-four knees (65%) had rotating-hinge TKA components implanted for aseptic etiologies, while 144 knees (35%) were managed with the components in 2-stage reimplantation following infection. Rotating-hinge TKA implants were used for complex primary procedures in 74 knees (18%) and as a revision construct in 334 knees (82%). Clinical outcomes were assessed with the Knee Society scoring system, survivorship analyses, and cumulative incidence of revision. The mean age of the patients at the time of the index arthroplasty was 69 years, and the mean duration of follow-up was 4 years (range, 2 to 12 years). At the most recent follow-up, the mean Knee Society knee score had increased from 51 points preoperatively to 81 points (p < 0.0001), and the mean Knee Society functional score had increased from 26 to 36 points (p < 0.0001). At a mean of 4 years, loosening of components was observed in 13 (3.7%) of 349 knees. At the most recent follow-up, 59 revision procedures and 25 reoperations had been performed. The cumulative incidence of any revision was 9.7% at 2 years and 22.5% at 10 years. The cumulative incidence of revision for aseptic loosening was 1.7% at 2 years and 4.5% at 10 years. Metaphyseal cones were used in 114 knees (28%). Survivorship analysis revealed a trend toward a lower risk of revision (hazard ratio [HR] = 0.69; 95% confidence interval [CI] = 0.39 to 1.22; p = 0.20) and reoperation (HR = 0.51; 95% CI = 0.22 to 1.19; p = 0.12) in patients with metaphyseal cones, despite their use in the most severe of bone defects. Contemporary rotating-hinge TKA implants had a low 10-year cumulative incidence of revision for aseptic loosening of 4.5%. Greater use of metaphyseal fixation has aided this improvement. Patients can expect substantial improvements in clinical outcomes with this revision strategy. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Development and Verification of Novel Porous Titanium Metaphyseal Cones for Revision Total Knee Arthroplasty

BackgroundPorous metaphyseal cones are widely used in revision knee arthroplasty. A new system of porous titanium metaphyseal cones has been designed based on the femoral and tibial morphology derived from a computed tomography–based anatomical database. The purpose of this study is to evaluate the initial mechanical stability of the new porous titanium revision cone system by measuring the micromotion under physiologic loading compared with a widely-used existing porous tantalum metaphyseal cone system. MethodsThe new cones were designed to precisely fit the femoral and tibial anatomy, and 3D printing technology was used to manufacture these porous titanium cones. The stability of the new titanium cones and the widely-used tantalum cones were compared under physiologic loading conditions in bench top test model. ResultsThe stability of the new titanium cones was either equivalent or better than the tantalum cones. The new titanium femoral cone construct had significantly less micromotion compared with the traditional femoral cone construct in 5 of the 12 directions measured (P < .05), whereas no statistical difference was found in 7 directions. The new porous titanium metaphyseal tibial cones demonstrated less micromotion in medial varus/valgus (P = .004) and posterior compressive micromotion (P = .002) compared with the traditional porous tantalum system. ConclusionThe findings of this biomechanical study demonstrate satisfactory mechanical stability of an anatomical-based porous titanium metaphyseal cone system for femoral and tibial bone loss as measured by micromotion under physiologic loading. The new cone design, in combination with instrumentation that facilitates surgical efficiency, is encouraging. Long-term clinical follow-up is warranted.

The Use of Metaphyseal Cones for Bone Defects in Revision Total Knee Arthroplasty.

The Use of Metaphyseal Cones for Bone Defects in Revision Total Knee Arthroplasty.

Metaphyseal bone loss in revision knee arthroplasty.

The etiology of bone loss encountered during revision total knee arthroplasty (TKA) is often multifactorial and can include stress shielding, osteolysis, osteonecrosis, infection, mechanical loss due to a grossly loose implant, and iatrogenic loss at the time of implant resection. Selection of the reconstructive technique(s) to manage bone deficiency is determined by the location and magnitude of bone loss, ligament integrity, surgeon experience, and patient factors including the potential for additional revision, functional demand, and comorbidities. Smaller, contained defects are reliably managed with bone graft, cement augmented with screw fixation, or modular augments. Large metaphyseal defects require more extensive reconstruction such as impaction bone grafting with or without mesh augmentation, prosthetic augmentation, use of bulk structural allografts, or use of metaphyseal cones or sleeves. While each technique has advantages and disadvantages, the most optimal method for reconstruction of large metaphyseal bone defects during revision TKA is not clearly established.

Porous metal metaphyseal cones for severe bone loss: when only metal will do.

Metaphyseal bone loss is common with revision total knee replacement (RTKR). Using the Anderson Orthopaedic Research Institute (AORI) classification, type 2-B and type 3 defects usually require large metal blocks, bulk structural allograft or highly porous metal cones. Tibial and femoral trabecular metal metaphyseal cones are a unique solution for large bone defects. These cones substitute for bone loss, improve metaphyseal fixation, help correct malalignment, restore the joint line and may permit use of a shorter stem. The technique for insertion involves sculpturing of the remaining bone with a high speed burr and rasp, followed by press-fit of the cone into the metaphysis. The fixation and osteoconductive properties of the porous cone outer surface allow ingrowth and encourage long-term biological fixation. The revision knee component is then cemented into the porous cone inner surface, which provides superior fixation compared with cementing into native but deficient metaphyseal bone. The advantages of the cone compared with allograft include: technical ease, biological fixation, no resorption, and possibly a lower risk of infection. The disadvantages include: difficult extraction and relatively short-term follow-up. Several studies using cones report promising short-term results for the reconstruction of large bone defects in RTKR.

A 30-mm cemented stem extension provides adequate fixation of the tibial component in revision knee arthroplasty.

The optimal stem length and method of fixation for the tibial component in revision knee arthroplasty remains controversial. The use of a cemented 30-mm stem extension provides certain advantages compared with other methods of fixation, but there are few published results. We therefore asked (1) what is the survivorship (with respect to loosening and repeat revision) of tibial component revisions when a 30-mm stem extension is used; and (2) what factors are associated with the appearance tibial radiolucent lines? We retrospectively reviewed 54 patients (58 knees) with fixation of the revision tibial component with a 30-mm cemented stem extension; another seven patients died and 11 patients had these components but were lost to followup. These implants represented 74% of our tibial revisions during the period in question (76 of 103); general indications for using them were need for a varus-valgus constrained liner or proximal bone loss requiring a metaphyseal cone or metal augment with an intact diaphysis. The Anderson Orthopaedic Research Institute tibial defect was Grade 1 in 37, 2A in 10, 2B in four, and Grade 3 in seven knees; constrained liners were used in 34% (20 of 58 knees). Patients were evaluated and followed for a mean of 5 years (range, 2-12 years). There were no revisions for tibial component loosening. One patient had débridement and liner exchange for late infection. Radiolucent lines were seen in 25 tibial components but only eight knees had radiolucencies in four or more zones. There were significantly fewer radiolucencies in revisions that used metaphyseal cones (20 in eight knees with cones compared with 53 in 17 without, p=0.013). The cemented 30-mm tibial stem extension provided excellent fixation in knee revision arthroplasty, even with metaphyseal defects and constrained polyethylene liners, although this series included relatively few patients with severe tibial defects. Longer followup is required for patients with radiolucent lines to confirm that the fixation will remain durable. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Tantalum Cones in Revision Total Knee Arthroplasty. A Promising Short-Term Result With 29 Cones in 21 Patients

Twenty-nine porous tantalum metaphyseal cones were implanted in 21 patients (14 women and 7 men) during revision TKA. The average age at the time of the procedure was 73.3years. Sixteen revisions were considered aseptic and 5 were reimplantations after sepsis. Eight patients had stemmed revision implants and thirteen primary designs. According to the Anderson Orthopaedic Research Institute bone defect classification, femoral defects were rated as F3 in 14 knees and F2B in 3 knees. Tibial defects were rated as T2A in 3 cases, T2B in 3 cases and T3 in 5 cases. A femoral cone was inserted in 10 patients, a double cone (femur and tibia) in 8, and a single tibial cone in 3. A rotating hinge knee prosthesis (RHK, Zimmer) was inserted in 10 patients and a constrained condylar prosthesis (LCCK, Zimmer) in 11 patients. The diaphysis was cemented in 9 cases and, in 11 cases, just the metaphysis. At an average follow up of 36months only one reconstruction was removed due to persistent infection. All metaphyseal cones showed evidence of stable osseointegration. According to the Knee Society Score the results were rated as excellent in 12 cases, good in 5 cases, fair in 3 and poor in 1 case. In the short term, porous tantalum metaphyseal cones provided structural support for large femoral and tibial defects. They also provided the environment for bone graft osseointegration, repair of femoral fractures and effective interdigitation of cement mantle into the trabecular metal cone.

Reconstruction of Complex Distal Femur and Proximal Tibia Defects Using Tantalum Cones

As the number of primary total knee arthroplasties increase, revision procedures with massive bone defects will also increase. Although multiple reconstructive options have been recommended, porous tantalum metaphyseal cones have the advantage of improved biological fixation because of their high porosity, interconnected pore space, and a modulus of elasticity 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 large contained or uncontained osseous defects that are typically categorized as Anderson Orthopaedic Research Institute type 2B or greater. 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 allows the surgeon to choose a size and position that best fits the individual defect encountered. Moreover, tantalum cones can be used with any revision system. Short-term clinical follow-up indicates that porous tantalum metaphyseal cones effectively provide structural support with the potential for long-term biological fixation and durable reconstructions.

Bone mineral density changes of the proximal tibia after revision total knee arthroplasty. A randomised study with the use of porous tantalum metaphyseal cones

Forty patients were enrolled in a prospective randomised study using conventional method or "Trabecular Metal Cone" (TM Cone) (Zimmer inc., Warsaw, USA) for reconstruction of bone loss of the proximal tibia during revision total knee arthroplasty (rTKA). The aim was to evaluate changes in bone mineral density (BMD) at the proximal tibia. Thirty-six patients [median 67 years (range: 40-85 years)] received rTKA with NexGen® (Zimmer Warsaw, USA) revision system. Knee Society´s Knee Scoring System and the Anderson Orthopaedic Research Institute (AORI) bone classification was used. Changes in BMD were measured by dual energy X-ray absorptiometry (DEXA). Knee and function score improved in both groups. No significant changes between the groups were found. Changes in BMD within the two groups were quite similar. Overall decreases in BMD of 0.1 - 5.4 % were found in both groups (ROI 1-6) postoperative to 12 months of follow-up, except that ROI 7 showed an increase in BMD (0.8 - 1.3 %). After 24 months of follow-up, an increase in BMD was found along the stem (ROI 2-5) of 1.9 - 6.3 % , with significant changes in the TM Cone Group (ROI 3, 4, 5) . No significant changes in BMD between the groups were found. The bone remodelling pattern was almost the same in the two groups after two years.

Early Results of the Use of Tantalum Femoral Cones for Revision Total Knee Arthroplasty

The optimum treatment method for large femoral bone defects during revision knee replacement has not been established. The purpose of the present study was to determine the initial results associated with the use of porous tantalum metaphyseal cones for the treatment of severe femoral bone loss at the time of revision total knee arthroplasty. Porous tantalum metaphyseal cones were implanted during twenty-four revision total knee replacements. The study group included thirteen women and eleven men with a mean age of sixty-four years at the time of the procedure. The indications for the revision procedure included aseptic loosening of the femoral component (eleven patients), second-stage reimplantation for the treatment of deep infection (seven patients), severe osteolysis around a well-fixed femoral component (three patients), periprosthetic femoral fracture (two patients), and severe knee instability (one patient). The patients were followed for an average of thirty-three months (range, twenty-four to fifty months). Overall, the average Knee Society clinical score improved from 55 points preoperatively to 81 points at the time of the latest follow-up. Radiographic evaluation was completed for twenty patients after a mean duration of follow-up of thirty-five months. All femoral cones appeared well fixed radiographically, with no evidence of complications related to the cone. At the time of short-term follow-up, the porous tantalum metaphyseal femoral cones effectively provided structural support for the femoral implants of a revision total knee arthroplasty in this series. The potential for long-term biologic fixation may provide durability for reconstructions. Long-term follow-up and comparison with alternative reconstructive techniques will be required to evaluate the true effectiveness of this implant.

Double-barrel fibular graft for metaphyseal areas reconstruction around the knee

The metaphyses around the knee (distal femoral and proximal tibial) are junction areas subject to considerable stress. Double-barrel free vascular fibular graft (D-FVFG) provides good bone augmentation and restores the metaphyseal cone; the present study assessed its capacity to restore metaphyseal anatomy and axis and investigated its impact on the neighboring knee joint. Eight D-FVFGs performed for metaphyseal segmental bone defect were followed up for a mean 6.5 years (range, 3-14 years). There were seven femoral nonunions, five of which were septic, and one chondrosarcoma of the tibia. Osteosynthesis used an external fixator (EF) in six cases (four of which bridged the knee), a double plate on the tibia in one case, and intramedullary nailing of the femur in two cases, including one to replace an EF. Adjuvant bone graft was associated in six cases. A protective leg brace was maintained for a mean 16.0±4.0 months. Three arthrolyses were required after final union. Union was achieved in all cases, after a mean 6.4±2.1 months. Sixty-four percent of defect volume was reconstructed. The immediate postoperative mechanical femorotibial angle was 180.3±6.0° and 174.5±5.7° at FU. Mean knee flexion was 96.9±36.0° and extension -5.0±10.0°. Three patients showed symptomatic arthritis at follow-up. D-FVFG satisfactorily restored the anatomy of the metaphyseal area. EF knee bridging seemed to impair varus correction, on top of the systematic problem of stiffness. When possible, internal fixation in first intention or as EF replacement appears to be preferable. Arthritic deterioration of the knee is worsened by initial joint lesions and femorotibial varus. Level IV. retrospective.