High survival rate at mid-term follow up of porous tantalum cones for bone defects in revision total knee replacement: A 3-11 years follow up report

Metaphyseal Fixation in Revision Total Knee Arthroplasty

➢ Bone defect management is challenging, but essential, in revision total knee arthroplasty.➢ Appropriate metaphyseal fixation is crucial for stability and implant support.➢ Allografts have been traditionally used to address large defects, but the advent of highly porous metaphyseal cones and sleeves has attracted attention during the past years.➢ Metaphyseal implants are now available in a variety of shapes and sizes to meet various clinical needs.➢ These devices can successfully fill large defects, can better support revision implants, and can achieve long-term biologic fixation.➢ Very good intermediate-term outcomes have been reported with the available metaphyseal implants, using fully cemented or press-fit stems.➢ More research is warranted to further assess surgical indications and the strengths and weaknesses of the various implants used for metaphyseal fixation.

The Fate of Highly Porous Titanium Tibial Cones in Revision Total Knee Arthroplasty: A Multicenter 5-Year Minimum Follow-Up Study

BACKGROUND

The survivorship of tibial metaphyseal cones following revision total knee arthroplasty (rTKA) has been reported. However, literature comparing cone midterm survivorship (from five to 10 years after rTKA) between septic (infection history on the joint) and aseptic revisions is scarce. Therefore, we sought: (1) to assess the overall tibial cone survivorship rate after rTKA; and (2) to compare cone survivorship between septic and aseptic revisions.

METHODS

A multicenter retrospective chart review of 231 patients who underwent rTKA using highly porous titanium tibial metaphyseal cones (June 15, 2015 to May 4, 2018) was conducted. A total of 80 patients were excluded, leaving 151 rTKA patients (40 septic and 111 aseptic knees) for analyses. Demographics and surgical characteristics were noted. The mean age and body mass index of patients were 64 years and 34.6, respectively. Survivorship rates of rTKA and tibial cones were established. The mean follow-up of surviving cones was six years (range, five to eight).

RESULTS

Of 151 patients included, 30 (19.9%) underwent a subsequent total knee arthroplasty revision. At the latest follow-up, according to the Knee Society grading system, 115 (95.0%) of surviving rTKAs were deemed stable, three (2.5%) warranted close observation, and three (2.5%) were loose. Only 14 (9.3%) tibial cones were ultimately extracted. Thus, the overall cone survivorship rate was 90.7% with no significant differences between survivorship rates of cones implanted during either septic (87.5%) or aseptic (91.9%) rTKAs (P = 0.52).

CONCLUSIONS

The survivorship of tibial metaphyseal cones was good at a minimum follow-up of five years with no significant differences in survivorship between septic and aseptic rTKAs. Our data support the use of highly porous titanium tibial cones to improve metaphyseal fixation during rTKA even when there is a history of a knee infection.

International, consensus-based, indications and treatment options for knee arthroplasty in acute fractures around the knee

BACKGROUND

In the landscape of knee-related health issues there has been a notable shift in treatment protocols. Nowadays, there is a growing trend toward primary total knee arthroplasty (TKA) in the event of periarticular knee fractures. A review of the literature on TKA in acute knee fractures has been done in order to provide scientific evidence to the four statements submitted for voting to the members of the European Knee Society (EKS).

MATERIALS AND METHODS

A literature review has been performed around four topics of TKA in acute knee fractures, specifically: 1) The indications for TKA in acute knee fractures are undoubtful and clear; 2) Pre-existing osteoarthritis is not mandatory for the indication of TKA in acute fractures, while age, co-morbidities and type of fracture are; 3) A series of established criteria with scores to give indication for TKA (approved algorithm) is needed; and 4) This (complex) surgery must be performed in referral centers with all technical options and specific peri-operative management and post-operative care.

RESULTS

The panel of experts therefore believes that the indications cannot be considered undoubtful and clear. According to the literature up to the time of the consensus vote, there was no objective method for deciding on the treatment to offer the patient (Agree: 34.1%, Disagree: 61%, Abstain: 4.9%). It emerges that there are no mandatory conditions for the treatment of acute knee fractures with TKA (Agree: 32.3%, Disagree: 51.6%, Abstain: 16.1%). However, there are several characteristics to consider for a multifactorial evaluation rather than being limited to a single condition. While the consensus has highlighted a need for a scoring system to guide surgical decisions in periarticular knee fractures (Agree: 88.24%, Disagree: 8.82%, Abstain: 2.94%), research in the literature has confirmed that, to date, no validated algorithm exists. After the vote, a score was proposed, which requires validation. Although the panel of experts does not deem it necessary for this surgery to be reserved for reference centers (Agree: 32.35%, Disagree: 50%, Abstain: 17.65%), literature suggests that it is crucial that before undertaking knee arthroplasty in the setting of an acute fracture around the knee, the orthopedic surgeon is confident with all the necessary skills for a complex intervention that requires advanced knowledge and practical competence in osteosynthesis and revision TKA.

CONCLUSION

This discussion on the questions voted by the panel of experts has allowed for an in-depth exploration of a topic of interest, assessing indications, contraindications, types of possible treatment, and the critical aspects to consider when treating an acute fracture around the knee with a prosthesis. It is important to consider that the choice must be carefully weighed, evaluating the risks and benefits, with an increasingly need for a scoring system for selecting the most appropriate treatment.

Isolated aseptic loosening in total knee arthroplasty: a comprehensive 10-year review of partial vs. total component revisions

BACKGROUND

In total knee arthroplasty (TKA), isolated aseptic loosening (IAL) requires the replacement of prosthetic components, with ongoing debate regarding the effectiveness of partial component revision (PCR) compared to total component revision (TCR). This study aims to compare implant survival and surgical outcomes between PCR and TCR in the context of IAL.

METHODS

This retrospective study analyzed data from 285 patients who underwent revision TKA for IAL between January 2000 and December 2013. After applying exclusion criteria, 112 patients were included in the analysis-60 undergoing TCR and 52 undergoing PCR.

RESULTS

PCR was associated with shorter operative times and hospital stays compared to TCR, alongside significant differences in the choice of revision prostheses. Although the prosthesis failure rates were comparable between the groups (13.6% for TCR and 18.33% for PCR), significant risk factors for failure were identified, including a canal filling ratio (CFR) below 0.8 and a discrepancy over 0.2 between CFR views. However, no significant differences in overall survivorship were observed between the groups.

CONCLUSIONS

Both PCR and TCR provide similar survival rates and clinical outcomes for managing IAL in TKA. PCR provides advantages in terms of surgical efficiency and patient recovery, while reducing the need for more constrained prosthetic solutions. The study identifies CFR as a critical predictor of prosthesis failure, highlighting the importance of detailed preoperative planning and implant selection. These findings contribute valuable insights for improving revision strategies in IAL, enhancing surgical outcomes in TKA.

LEVEL OF EVIDENCE

III.

Good Short-Term Survivorship of Constrained Condylar Revision Knee Implants With Medial Pivot Kinematics: A Level IV Retrospective Study

BACKGROUND

The need for revision total knee arthroplasty surgery is increasing worldwide, and, in many cases, a constrained implant is required to provide joint stability. The purpose of this study was to examine the early loosening and functional outcome of a novel constrained condylar (CCK) revision total knee system designed to have medial pivot (MP) kinematics.

METHODS

A retrospective cohort study was performed, collecting clinical data from all patients who underwent revision total knee arthroplasty using a novel MP CCK system with a minimum four-year clinical follow-up. Patient demographics, survivorship, complications, and Forgotten Joint Score were analyzed based upon chart review.

RESULTS

There were 49 patients available for follow-up, who had a 100% survivorship free of aseptic loosening. All-cause revision survivorship was 92%. There were 4 patients who subsequently underwent rerevision. The causes for rerevision included periprosthetic joint infection in 2 patients, coronal plane instability in one patient, and a traumatic knee dislocation in one patient. There were 45 patients who completed the Forgotten Joint Score, who had an average of 49.8 (± 32.8, range 6.25 to 100).

CONCLUSIONS

At 4 years, mid-term follow-up, this novel CCK revision total knee system designed to have MP kinematics had good patient-reported outcomes with no revision for aseptic loosening. Future studies should evaluate the mid- and long-term survivorship of this innovative implant.

Porous Tantalum Tibial Metaphyseal Cones in Revision Total Knee Arthroplasty: Excellent 10-Year Survivorship

BACKGROUND

Highly porous metal tibial metaphyseal cones (TMCs) are commonly utilized in revision total knee arthroplasty (TKA) to address bone loss and obtain biologic fixation. Mid-term (5 to 10 year) studies have previously demonstrated excellent survivorship and high rates of osseointegration, but longer-term studies are lacking. We aimed to assess long-term (≥ 10 year) implant survivorship, complications, and clinical and radiographic outcomes after revision TKA with TMCs.

METHODS

Between 2004 and 2011, 228 revision TKAs utilizing porous tantalum TMCs with stemmed tibial components were performed at a single institution and were retrospectively reviewed. The mean age at revision was 65 years, the mean body mass index was 33, and 52% were women. Implant survivorship, complications, and clinical and radiographic outcomes were assessed. The mean follow-up was 6.3 years.

RESULTS

The 10-year survivorship free of aseptic loosening leading to TMC removal was 97%, free of any TMC removal was 88%, free of any re-revision was 66%, and free of any reoperation was 58%. The most common indications for re-revision were periprosthetic joint infection, instability, and aseptic femoral component loosening. The 10-year nonoperative complication rate was 24%. The mean Knee Society scores increased from 38 preoperatively to 69 at 10 years. There were 8 knees that had evidence of partial, progressive tibial radiolucencies at 10 years.

CONCLUSIONS

Porous tantalum TMCs demonstrated persistently durable longer-term survivorship with a low rate of implant removal. The rare implant removals for component loosening or instability were offset by those required for periprosthetic joint infection, which accounted for 80% of cone removals. Porous tantalum TMCs provide an extremely reliable tool to address tibial bone loss and achieve durable long-term fixation in revision TKA.

LEVEL OF EVIDENCE

IV.

Biomechanical analysis of patient specific cone vs conventional stem in revision total knee arthroplasty

BACKGROUND

In revision total knee arthroplasty, addressing significant bone loss often involves the use of cemented or press-fit stems to ensure implant stability and long-term fixation. A possible alternative to stem was recently introduced utilizing custom-made porous metaphyseal cones, designed to reconstruct the missing tibial and femoral geometries. Early clinical and radiological assessments have shown promising results. The objective of this research was to biomechanically evaluate the performances of these custom-made cones.

METHODS

The biomechanical study was conducted using a validated finite element model. The bone geometries of a patient (selected for their history of four knee revisions due to infection and periprosthetic fractures, followed by a successful treatment with custom-made 3D-printed metaphyseal cones) were employed for the study. On these bone models, different revision scenarios were simulated and examined biomechanically: (A) custom-made cementless metaphyseal cones; (B) cemented stems; (C) press-fit stems; (D) distal femoral reconstruction with press-fit stem. All the models were analyzed at 0 °and 90 °of flexion, under physiological load conditions simulating daily activities; stress distribution, average Von-Mises stresses and risk of fracture were then analyzed and compared among configurations.

RESULTS

The use of custom-made 3D-printed cones exhibited the most favorable stress distribution in both femoral and tibial bones. Tibial bone stress was evenly distributed in custom-made cone configurations, while stress concentration was observed in distal regions for the other scenarios. Additionally, custom-made cones displayed overall homogeneity and lower stress levels, potentially contributing to limit pain. Symmetrical stress distribution was observed between the lateral and medial proximal tibia in custom-made cone models, whereas other scenarios exhibited uneven stress, particularly in the anterior tibial bone.

CONCLUSIONS

The biomechanical analysis of porous custom-made metaphyseal cones in re-revision arthroplasties is in agreement with the positive clinical and radiological outcomes. These findings provide valuable insights into the potential benefits of using custom-made cones, which offer more uniform stress distribution and may contribute to improve patient outcomes in revision TKA procedures. Further studies in this direction are warranted to validate these biomechanical findings.

Are Flexible Metaphyseal Femoral Cones Stable and Effective? A Biomechanical Study on Hinged Total Knee Arthroplasty

BACKGROUND

Cones currently available in the market are rigid, and unless they are custom-specific designed, are unable to correctly adapt to the shape of the patient's bone. Therefore, flexible metaphyseal cones have been recently introduced to reduce potential bone trauma during implantation. Even if a preliminary clinical study on their use has shown promising results, no biomechanical study evaluates and quantifies their mechanical efficacy and safety.

METHODS

Two commercial versions of flexible cones were analyzed in this study using finite element analysis, based on a previously validated model. Each cone geometry was modeled both as flexible and as rigid, and implanted following surgical guidelines. Three activities were simulated in this study and compared among configurations: surgical impaction, walking, and chair rise.

RESULTS

During impaction, results showed considerably reduced stress in the flexible cones in comparison with rigid ones; the stress resulted was also better distributed and more homogeneous all over the cortical bone, with lower bone peaks. Considering the 2 different activities, the analysis did not show any remarkable differences between flexible and rigid cones both in terms of bone stress and implant micromotion.

CONCLUSIONS

The findings demonstrate that metaphyseal flexible cones allow macrodeformation during impaction due to their flexibility, and therefore, are safer in comparison with rigid cones. However, for the daily tasks investigated, results showed no major differences between rigid and flexible cones in terms of bone stress, implant stability, and micromotion. Therefore, their mechanical performances can be considered similar to the rigid cone.

Cause for concern? Significant cement coverage in retrieved metaphyseal cones after revision total knee arthroplasty

BACKGROUND

Metaphyseal cones are used to manage bone loss in revision total knee arthroplasty with increasing popularity. Post-operative radiographs and explant procedures suggest that cement may extrude around the cone implant into the cone-bone interface and prevent biologic in- or on-growth. The purpose of this study was to perform a retrieval analysis to describe the pattern of direct cementation onto the porous surface area of metaphyseal cones.

METHODS

Eighteen tibial and femoral cones were identified in an institutional implant retrieval registry. Anterior, posterior, medial and lateral quadrants were digitally mapped for direct cementation, bone ongrowth and fibrous ongrowth were calculated as a percentage of the porous surface area. Plain radiographs from prior to cone explant were analyzed for the presence of cement in all four quadrants and compared with results of the retrieval analysis.

RESULTS

Mean bone ongrowth was 25%, direct cementation was 24% (31% in tibial cones) and fibrous ongrowth was 29% of the porous surface area of the retrieved cones. There were no significant differences when comparing patterns of bone or fibrous ongrowth or cementation between anterior, posterior medial and lateral porous surfaces for tibia cones, femoral cones or all cones grouped together. Plain radiographs significantly underestimated the amount of cement covering the cone (p = 0.02).

CONCLUSION

In this retrieval study, we found significant cement extrusion around the porous surface of metaphyseal cones in revision TKAs. Optimizing the cone-bone interface may reduce the risk of cement extrusion and theoretically reduce the risk of aseptic loosening.

Excellent mid- to long-term survival of tantalum metal cones in a case series of revision knee arthroplasty with severe bony defects

PURPOSE

Severe metaphyseal bone defects remain a challenge and represent a growing problem in revision total knee arthroplasty (RTKA). The purpose of this study was to examine the survival of first-generation tantalum metal cones (TMC) and to assess clinical and radiographic data obtained from mid- to long-term follow-ups (FU) after RTKA with severe bony defects.

METHODS

This retrospective case series included 100 consecutive patients of the same centre, who underwent RTKA surgery with TMC for tibia and/or femur bone defects between January 2011 and December 2015. Fourteen patients had died and six were lost for FU, leaving a total of eighty patients (one hundred and twelve TMC) for final evaluation. Clinical parameters including the Knee Society Score (KSS), visual analogue scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and range of motion (ROM) were determined preoperatively based on the patients' medical charts, and assessed again during the final FU after an average of 6.1 (5-9) years postoperative. Standardised postoperative X-rays were analysed during the final FU visit for osseointegration of the cones, and any signs of implant loosening were assessed with the modified Knee Society Radiographic review criteria. Perioperative and postoperative complications, reoperations, as well as implant and cone re-revisions were analysed. Survivorship analysis was performed with (a) cone-related revision for any reason and (b) implant component revision for any reason.

RESULTS

Previous RTKA had to be performed due to 64 (80%) aseptic and 16 (20%) septic failures. At the final FU, 75 (94%) tibia and 76 (95%) femur TMCs and implants were clinically stable. One patient experienced loosening of cones and implants at the femur and tibia but denied re-revision surgery. There were eight (10%) reoperations including two early wound healing problems, two inlay changes, two periprosthetic fractures, one debridement, antibiotics and implant retention (DAIR), and one secondary patella replacement. The six (7.5%) re-revisions included two aseptic loosening's of the opposite implant without TMC, one arthrodesis for recurrent instability, and three deep infections managed by two two-stage exchanges, and one amputation for persistent infection. At re-revision, all TMC cones were osteointegrated without signs of loosening. The determined clinical parameters showed significant (p < 0.001) postoperative improvement, and objective KSS was rated as excellent in 51%, and as good in 22% of patients at the final FU. The estimated 8-year Kaplan-Meier survival was 95% for TMC and 92.5% for implant components.

CONCLUSION

Tantalum metal cones (TMC) demonstrate a secure fixation for treatment of severe femoral and tibial metaphyseal bone defects during RTKA. This fixation concept showed excellent mid- to long-term clinical and radiographic outcomes with promising 8-year survival rates for cones and implant components.

LEVEL OF EVIDENCE

Retrospective cohort study, Level IV.

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

BACKGROUND

Two-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.

METHODS

From 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.

RESULTS

In 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.

CONCLUSION

Metaphyseal 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.

Application of three-dimensional-printed porous tantalum cones in total knee arthroplasty revision to reconstruct bone defects

Purpose: Three-dimensional (3D) printing technology has emerged as a new treatment method due to its precision and personalization. This study aims to explore the application of a 3D-printed personalized porous tantalum cone for reconstructing the bone defect in total knee arthroplasty (TKA) revision.

Methods: Between November 2017 and October 2020, six patients underwent bone reconstruction using 3D-printed porous tantalum cones in TKA revision. The knee function was assessed using the Hospital for Special Surgery (HSS) score pre- and postoperatively. The pain was measured by the visual analog scale (VAS) pre- and postoperatively. The quality of life was measured using the 36-Item Short Form Health Survey (SF-36) to pre- and postoperatively evaluate the relief of pain. Operation time, intraoperative blood loss, postoperative drainage volume, and complications were also recorded. At the last follow-up, all patients received X-ray and computed tomography (CT) to confirm the effect of bone reconstruction.

Results: After an average follow-up duration of 26.3 months, no patients developed any operation-related complications. The average intraoperative blood loss and postoperative drainage volumes were 250.1 ± 76.4 ml and 506.7 ± 300.8 ml, respectively. At the last follow-up, the HSS score was significantly higher than that before operation, indicating that the knee function was significantly improved (p < 0.001). During the follow-up, the mean VAS score decreased and the mean SF-36 score increased, both of which were significantly improved compared with preoperative conditions (p < 0.001). Radiological examination at the final follow-up showed that cones implanted into the joint were stable and bone defects were effectively reconstructed.

Conclusion: This study demonstrated that 3D-printed porous tantalum cones could effectively reconstruct bone defects and offer anatomical support in TKA revision. Further studies are still needed to confirm the long-term effect of 3D-printed tantalum cones for reconstructing bone defects.