Tantalum Cones for Severe Bone Defects in Revision Knee Arthroplasty: A Minimum 10-Year Follow-Up

BackgroundTwo-to 6-year results of reconstruction of severe bone defects in revision total knee arthroplasty (TKA) with highly porous tantalum cones have been encouraging, but 10-year follow-up is lacking. The purpose of this study was to determine the minimum 10-year results of tantalum cones in revision TKA.MethodsFrom 2005 to 2010, 30 consecutive patients (30 knees) underwent revision TKA with the use of cones. All patients were followed clinically and radiographically for a minimum of 10 years. A total of 42 cones (25 tibial and 17 femoral) were used to reconstruct massive bone defects classified as Anderson Orthopaedic Research Institute Types 2A (10), 2B (12), and 3 (19). The mean age of the patients was 73 years (range, 55 to 84) at the time of revision. The indication for the revision included aseptic loosening (15 patients) and second-stage reimplantation for deep infection (15 patients). Six patients were lost to follow-up.ResultsIn total, 6 cones had to be revised. Minimum 10-year cone survivorship for any reason was 81% (25 of 31 cones). With cone revision for aseptic loosening as the end point, survivorship was 96% (30 of 31). No evidence of loosening or migration of any implant was noted on the most recent radiographs.ConclusionMetaphyseal fixation with tantalum cones in revision TKA demonstrated excellent survivorship and fixation at a minimum follow-up of 10 years. This type of metaphyseal reconstruction can be a durable option for revision TKA in patients who have massive bone defects.     

Bone loss management: A potpourri of options

Bone loss encountered during revision TKA can make proper alignment and fixation a challenge. Causes for bone loss in revision TKA include implant loosening, osteolysis, and iatrogenic from implant removal. Reproducible clinical success can be achieved if metaphyseal fixation is achieved [1]. In the absence of cancellous bone for cement fixation, metaphyseal augments placed without cement have shown promise in achieving fixation. First generation augments were modular solid titanium sleeves attached to a taper at the base of the core implant. The introduction of tantalum with its favorable mechanical qualities markedly increased the utility and utilization of metaphyseal augments, with several encouraging reports. These are either large augments where the bone is prepared with a burr, or later, small cones placed with a cannulated broaching technique. Both have addressed practical challenges, the first being limited by the reproducibility of bone preparation, and the second with excellent reproducibility of bone preparation but limited inner diameters. More recent highly porous titanium surfaces have further broadened the choices by allowing larger inner diameters to the cones, which allow the use of offset stems.This article aims to review the senior author's experience in managing bone loss in the revision TKA setting.     

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.     

Contemporary bone loss options: Rebuild,reinforce, and augment

Bone loss remains a major clinical challenge in revision total knee arthroplasty (TKA). Sources of bone loss include wear debris-induced osteolysis, infection, stress shielding, and periprosthetic fracture. Preoperative and intraoperative evaluations are necessary to classify the degree of bone loss in the revision setting including the location, size, and containment of defects. Reconstructive options for smaller, contained defects include morselized autograft/allograft, cementation with or without screw fixation, and metallic augments. For larger uncontained defects, structural allograft, metallic augments/cones, and prosthetic salvage systems become more common treatment options. Restoration of the bony envelope to provide support to the revision prosthesis is critical for a successful clinical outcome.     

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

Background

Some 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.

Management of large bone defects around the knee using porous tantalum trabecular metal cones during complex primary and revision total knee arthroplasty

With the rising numbers and indications of primary as well as revision total knee arthroplasty (TKA), managing bone defects around the knee is an emerging challenge. This retrospective study evaluates the outcomes of Trabecular Metal (TM) cones used to address bone defects in 79 (20 primary and 59 revision) TKA cases. Range of motion and Knee Society Score improved significantly postoperatively, with better outcomes in the primary TKA group. Complete osteointegration was observed in all the cases. At an average follow-up of 6.6 years, major complications requiring re-operation were seen in 4 (5%) knees. TM cones are an effective option for treating severe bone defects during TKA with predictable osteointegration and good long-term clinical outcomes.     

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.     

Metaphyseal fixation in revision total knee arthroplasty: indications and techniques

The need for revision total knee arthroplasty (TKA) is on the rise. Challenges to attaining durable, stable, well-functioning revision TKA include bony deficiency, periarticular osteopenia, deformity, and soft-tissue imbalance. Defect management often requires the use of stems, cement, metal augmentation, or allograft. Recently, there has been interest in obtaining fixation in the metaphyseal region in an attempt to improve construct stability while managing bony deficiency. Often, the metaphyseal bone is well vascularized, which provides an opportunity for additional fixation with cement, allograft, trabecular metal cones, or stepped porous-coated sleeves. Multiple series have documented good survivorship at short-term follow-up with trabecular metal cones and porous-coated sleeves. These newer technologies offer biologic fixation and are useful for treating bony defects that are not easily managed with other methods. Long-term studies are needed to determine the durability of these constructs. Concerns persist regarding stress shielding and difficulty of removal. Familiarity with the rationale and strategies for metaphyseal fixation in revision TKA is a valuable addition to the armamentarium of the revision surgeon.     

Clinical Survivorship of Aseptic Revision Total Knee Arthroplasty Using Hinged Knees and Tantalum Cones at Minimum 10-Year Follow-Up

BackgroundThe reconstruction of severe bone loss utilizing porous tantalum cones in patients undergoing revision total knee arthroplasty (TKA) has been established in the last years. However, reports on a long-term follow-up to assess the durability of such implants when combined with hinged knee designs are lacking. The current study aimed to evaluate the results of a previous study cohort at a minimum follow-up of 10 years.MethodsA retrospective review was performed. The initial study cohort comprised of 38 patients who underwent aseptic revision TKA between 2007 and 2009 at a single institution. After exclusion of the deceased patients and patients who were lost to follow-up, 25 patients with hinged knees and 32 cones implanted were included with a minimum follow-up of 10 years (mean = 126.5 months, range 120-142, standard deviation [SD] = 5.92). Survivorship was determined, and re-revisions were observed. Functional Knee Society Score was assessed.ResultsAfter a minimum of 10 years, 24 of 32 cones (75%) had survived without any exchange in 18 patients. Reasons for cone revision included aseptic loosening (5/32 cones; 15.6%) and periprosthetic joint infection (3/32 cones; 9.4%). In 4 of the five revisions due to aseptic loosening, pure hinged knees had been implanted. The mean functional Knee Society Score of the survivors was 69.6 points (range 10-100, SD = 30.85), and the average flexion ability of the knee was 92° (range 30°-120°, SD = 22.09).ConclusionPorous tantalum cones in revision TKA exhibited no favorable but reasonable long-term durability. Rotating-hinge designs should be used whenever possible to reduce the risk of aseptic loosening. Further comparative long-term analyses with other techniques or implants could inform us about the best treatment method.     

Three-Year Follow Up Utilizing Tantal Cones in Revision Total Knee Arthroplasty

There still is no consensus on the treatment of choice in revision knee arthroplasty associated with severe femoral and/or tibial bone loss. A total of 44 patients underwent revision knee arthroplasty procedures using porous tantalum cones (TM cones) to reconstruct tibial and/or femoral bone defects. At latest follow up after 37 months (32–48), 38 patients remained in the study. Tibial and femoral bone loss was categorized according to the AORI-Classification. The average preoperative KSS improved from 34 (range, 6–90) to 63 points (range, 7–90 points). The VAS improved from 7.5 to 4.8. Two patients required a re-revision due to aseptic loosening. There was no correlation between the different types of knee prosthesis implanted. Our study shows favourable clinical and radiological outcomes using TM cones in managing significant bone loss in revision total knee surgery.     

Tantalum Cones Provide Durable Mid-term Fixation in Revision TKA

Background

Multiple studies have reported favorable short-term outcomes using tantalum cones to reconstruct massive bone defects during revision TKA. However, longer-term followup is needed to determine the durability of these reconstructions.

Questions/purposes

We wished to determine the mid-term (1) reoperation rates for septic and aseptic causes, (2) radiologic findings of osseointegration, and (3) clinical outcomes based on the Knee Society score in patients who underwent revision knee arthroplasty with tantalum cones for severe bone loss.

Methods

We retrospectively evaluated records of 18 patients (18 knees) who underwent revision knee arthroplasty with use of tantalum cones between 2005 and 2008; the primary indications for use of this approach were to reconstruct massive bone defects classified as Anderson Orthopaedic Research Institute Types 2B and 3. During this period, all defects of this type were treated with this approach and no cones were used for more-minor defects. A total of 26 cones (13 tibial and 13 femoral) were implanted. There were 12 female and six male patients with a mean age of 73 years (range, 55–84 years) at the time of revision. The indication for the revision included aseptic loosening (five patients) and second-stage reimplantation for deep infection (13 patients). Patients were followed for a mean of 6 years (range, 5–8 years). No patient was lost to followup. Clinical and radiographic outcomes were assessed with the Knee Society clinical rating system and radiographic evaluation system.

Results

There have been two reoperations for recurrent infection; at surgery, the two cones showed osseointegration. No evidence of loosening or migration of any implant was noted on the most recent radiographs. Knee Society knee scores improved from a mean of 31 points before surgery to 77 points at latest followup (p < 0.001), and function scores improved from a mean of 22 points to 65 points (p < 0.001).

Conclusions

Tantalum cones for reconstruction of massive bone defects in revision knee arthroplasty provided secure fixation with excellent results at average followup of 6 years, although this series included relatively few patients. These devices are a viable option for surgeons to use in situations with severe bone loss. Further studies with longer followups are needed to confirm the durability of these reconstructions.

Level of Evidence

Level IV, therapeutic study.     

Bone Defects in Revision Total Knee Arthroplasty and Management

This article reviews the recent updates in revision of total knee arthroplasty (RTKA). We reviewed the recent articles on RTKA in databases including PubMed, Google Scholar, and SCOPUS. Total knee arthroplasty (TKA) involves the replacement of all three compartments of the knee in surgery of the knee joint to restore capacity and function. TKA is one of the most common and reliable surgical treatment options for the treatment of knee diseases. However, some patients require revision of TKA (RTKA) after primary TKA for various reasons, including mechanical wear, implant loosening or breakage, malalignment, infection, instability, periprosthetic fracture, and persistent stiffness. Unfortunately, the overall outcome of RTKA is not as satisfactory as for primary TKA due to the uncertainty regarding the actual success rate and the risk factors for failure. Cementation, modular metal augmentation, bone grafting, autologous bone grafting, allogenic bone grafting, impactation bone grafting, structural bone allografting, metaphyseal fixation, using porous titanium coated press fit metaphyseal sleeves and porous tantalum structural cones, and megaprostheses or customized prostheses are the currently available management options for RTKA. However, most of the management systems possess specific complications. Novel approaches should be developed to improve functional capacity, implant survival rates, and quality of life in a cost‐efficient manner.     

No Difference Between Trabecular Metal Cones and Femoral Head Allografts in Revision TKA: Minimum 5-year Followup

Background

Encouraging clinical results have been reported with the use of femoral head structural allografts and, more recently, trabecular metal cones for the management of large structural defects of the femur and tibia during revision total knee arthroplasty (TKA). However, to our knowledge, there are no published studies comparing these two techniques.

Questions/purposes

Compared with bulk allografts, do trabecular metal cones result in (1) better validated outcomes scores; (2) a lower risk of loosening or revision at 5 years; and (3) fewer surgical complications when used for the management of bone loss in revision TKA?

Methods

Between 2002 and 2008, three surgeons performed 450 TKA revisions, 45 (10%) of which were performed using augmentation of host bone; in those, femoral head allograft was used in 30 (75%) and trabecular metal cones in 15 (25%). From 2002 to 2007, femoral head allografts were used in all patients (28 patients); from 2007 to 2008, trabecular metal augments were used in all patients. There was a period of 1 year (16 knees) in which there was some overlap; during that time, femoral head structural allografts were used in cases in which we were unable to fit the defect or achieve adequate stability with trabecular metal cones. Followup was at a mean of 9 years (range, 5–12 years). No patients were lost to followup. Knee function and quality of life were assessed using the Oxford Knee Score, WOMAC, SF-12, and the UCLA activity score. Radiographs were assessed for signs of loosening. Surgical complications included superficial or deep infections, iatrogenic fractures, symptomatic deep venous thromboses or pulmonary emboli, and blood loss requiring transfusion; these were obtained from our database and from review of patients’ charts.

Results

The mean Oxford Knee Score in the allograft and trabecular metal cone groups was 91 (SD 10) and 91 (SD 14), respectively (95% confidence interval [CI], 88–94; p = 0.29). Mean WOMAC scores were 94 (SD 10) and 92 (SD 14), respectively (95% CI, 80–105; p = 0.52) and mean UCLA scores were 6 (SD 1.2) and 6 (SD 1.5), respectively (95% CI, 4–8; p = 0.49). Five- and 10-year survivorship of the allografts was 93% (95% CI, 77–98) and 93% (95% CI, 77–99), respectively. Survivorship at a mean of 5 years in the trabecular metal cones group was 91% (95% CI, 56–98). With the numbers available, there were no differences between the groups in terms of the frequency of surgical complications (3% [one of 30] versus 7% [one of 15]; odds ratio, 0.5; p = 0.632).

Conclusions

With the numbers available, we found no difference in pain, function, or repeat revision when comparing femoral head allografts and trabecular metal cones for severe bone defects during revision TKA. However, we used allografts for the larger bone defects. Based on these results, we believe that femoral head allografts and trabecular metal cones can both be used for the management of Anderson Orthopaedic Research Institute Types 2 and 3 defects. Future multicenter studies are required with larger numbers, cost analyses, and a longer duration of followup.

Level of Evidence

Level III, therapeutic study.

     

Can Tantalum Cones Provide Fixation in Complex Revision Knee Arthroplasty?

Background  

The best method for managing large bone defects during revision knee arthroplasty is unknown. Metaphyseal fixation using porous tantalum cones has been proposed for severe bone loss. Whether this approach achieves osseointegration with low complication rates is unclear.     

The structural allograft composite in revision total knee arthroplasty

Although morselized cancellous autograft or allograft has been shown to be highly successful for management of smaller cavitary defects in revision TKA, structural allografts often are required for large, contained, or uncontained osseous defects. Early clinical results of revision TKA using structural allografts have been encouraging with high allograft-host union rates, as long as adequate fixation is obtained. The use of intramedullary stems with sufficient length to engage diaphyseal bone is recommended to lessen load transmission to the structural allograft and to reduce the risk of late allograft collapse or fracture. Extensive preoperative planning, meticulous operative technique, and an extended period of postoperative rehabilitation are required for optimal     

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 73.3 years. 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 36 months 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.     

Intermediate-Term Survivorship of Metaphyseal Cones and Sleeves in Revision Total Knee Arthroplasty

BackgroundBoth cones or sleeves have been developed to address metaphyseal bone loss in revision total knee arthroplasty (TKA), but few studies have directly compared the outcomes. The purpose of this study was to compare the survivorship and aseptic revision rates between metaphyseal cones and sleeves at intermediate follow-up.MethodsWe reviewed a consecutive series of 1,172 revision TKA patients between 2009 and 2018 with a minimum two-year follow-up on all patients. We compared demographics, surgical indication, stem fixation, constraint, rates of rerevision, and Short-Form-12 scores between patients with cones and sleeves. A multivariate analysis was performed to identify the effect of cones and sleeves on aseptic rerevision. Kaplan-Meier curves were generated to compare aseptic survivorship of cones and sleeves.ResultsThere were 194 tibial cones (17%), 107 tibial sleeves (9%), 31 femoral cones (3%), and 135 femoral sleeves (12%) with a mean follow-up of 6.5 years (range: 2-12 years). There was no difference in demographics, indication, stem fixation, or constraint (P > .05). Although overall aseptic failure rates may be lower for tibial sleeves, there were no significant differences in survivorship over a one-year, two-year, and five-year follow-up when both tibial and femoral sleeves were directly compared to cones.ConclusionBoth tibial and femoral sleeves and cones perform well at an intermediate-term follow-up. Further investigation of these two are required to better understand their survivorship relative to each other.     

Bone loss in the distal anterior femur after total knee arthroplasty

Bone loss in the distal anterior femur in asymptomatic total knee arthroplasty (TKA) patients has been noted roentgenographically and during revision surgery. A retrospective roentgenographic review of 147 TKA cases was carried out to document bone loss. The influence that the mode of fixation (porous coated and cemented) and the implant design have on bone loss was examined. The time of onset and the progression of bone loss were studied. Bone loss occurred in the distal anterior femur in the majority of cases reviewed (68%). The prevalence of bone loss was independent of the mode of fixation and the implant design. By qualitative observation, roentgenographically detectable bone loss occurred within the first postoperative year and did not progress further. Previously three-dimensional finite element analysis demonstrated that the replacement of the bearing surface of the femur with a stiff metallic implant reduces the stress in the distal anterior femur by at least one order of magnitude. It is therefore speculated that the observed bone loss results from stress shielding. The apparent lack of progression may reflect the development of a new remodeling equilibrium under the altered stress conditions. The bone loss in the distal anterior femur described has not been implicated as a source of failure. However, since the bone strength in the femoral region is compromised as it becomes osteopenic, bone failure may occur with longer periods of cyclic loading. Furthermore, as a result of bone loss, revision arthroplasty may be more difficult.     

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.     

Treatment of Large Bone Defects With Trabecular Metal Cones in Revision Total Knee Arthroplasty : Short Term Clinical and Radiographic Outcomes

The early term results of 29 cases of revision total knee arthroplasty using highly porous trabecular metal cone implants for femoral and tibial major bone deficit reconstruction (Anderson Orthopedic Research Institute classification type 2B and 3) have been prospectively analyzed. Indications for revision surgery included: aseptic loosening/wear, staged reimplantation after infection, as well as periprosthetic fracture. At an average follow-up of 33 months (range, 13–73 months) the mean Knee Society Score and functional score statistically improved. Radiological follow-up revealed no evidence of loosening or migration of the constructs. No evidence of complications was noted in correlation with the use of trabecular metal cones. This study supports evidence that trabecular metal cones are an efficient and effective option for dealing with significant bone deficits and obtaining stable biological fixation in revision total knee arthroplasty.