Total knee arthroplasty with an uncemented trabecular metal tibial component: a registry-based analysis

Robotic assistance improves success of cementless component fixation in one total knee arthroplasty system

INTRODUCTION

New cementless implant designs in total knee arthroplasty (TKA) have begun to shift the longstanding practice of cemented fixation. With aseptic loosening a leading cause for revision of cementless implants, initial osteointegration is critical for component survivorship. Robotic-assisted TKA (RA-TKA) has shown promising results in recent literature at improving component accuracy. The current study aims to evaluate if robotic assistance affects the success of cementless fixation in primary TKA.

METHODS

445 cementless primary TKA components from one manufacturer implanted by five surgeons between June 2018 and October 2022 were retrospectively reviewed. Those with minimum one-year follow-up were analyzed. Femoral and tibial components were reviewed separately and grouped based on whether manual or RA-TKA from the same manufacturer was performed. Fisher's exact test was used to analyze if aseptic loosening rates were different between the two techniques.

RESULTS

373 (82%) cementless components from a single knee system were included. 146 femoral and 103 tibial components were implanted using RA-TKA, while 63 femoral and 61 tibial components were implanted manually. At a mean follow-up of 18 months (range, 12 to 51 months), successful fixation was achieved in 96.2% of all components. No femoral components from either group were revised due to aseptic loosening. Four manually implanted vs. no robotically assisted tibial components were revised due to aseptic loosening (6.6% vs 0.0%; P = 0.038).

CONCLUSION

The performance of modern cementless femoral components was excellent with or without robotic assistance, however RA-TKA improved the survivorship of the same system's cementless tibial component.

LEVEL OF EVIDENCE

Level III.

Fixation options for total knee arthroplasty: a comprehensive literature review

Total knee arthroplasty is a consistently successful, cost-efficient, and highly effective surgical procedure for treating severe knee osteoarthritis. The success and longevity of total knee arthroplasty depend significantly on the fixation method used to secure the prosthetic components. This comprehensive review examines the primary fixation methods (cemented, cementless, and hybrid fixation), analysing their biomechanics, clinical outcomes, advantages, and disadvantages, focusing on recent advances and trends in total knee arthroplasty fixation.

Cementless Total Knee Arthroplasty: A State-of-the-Art Review

» The demographic profile of candidates for total knee arthroplasty (TKA) is shifting toward younger and more active individuals.» While cemented fixation remains the gold standard in TKA, the interest is growing in exploring cementless fixation as a potentially more durable alternative.» Advances in manufacturing technologies are enhancing the prospects for superior long-term biological fixation.» Current research indicates that intermediate to long-term outcomes of modern cementless TKA designs are comparable with traditional cemented designs.» The selection of appropriate patients is critical to the success of cementless fixation techniques in TKA.» There is a need for high-quality research to better understand the potential differences and relative benefits of cemented vs. cementless TKA systems.

Efficacy of cementless porous tantalum tibial components versus cemented tibial components in primary total knee arthroplasty: A meta-analysis

BACKGROUND

Total knee arthroplasty involves the use of cemented tibial components for fixation. In recent years, cementless porous tantalum tibial components have been increasingly utilized. The aim of this meta-analysis was to compare the efficacy of cementless porous tantalum tibial components with traditional cemented tibial components in terms of postoperative outcomes following total knee arthroplasty.

METHODS

Relevant literature was retrieved from Cochrane Library, PubMed, Embase, and Web of Science using the search terms "(trabecular metal OR Porous tantalum)" AND "knee" up to July 2023. The weighted mean difference with a 95% confidence interval was used as the effect size measure to evaluate the functional recovery of the knee joint, radiological analysis, complications, and implant revisions between cementless porous tantalum tibial components and traditional cemented tibial components after total knee arthroplasty. Review Manager 5.3 was utilized to conduct a comparative analysis of all included studies.

RESULTS

Nine studies with a total of 1117 patients were included in this meta-analysis, consisting of 447 patients in the porous tantalum group and 670 patients in the cemented group. Radiological analysis demonstrated that the porous tantalum group had better outcomes than the cemented group (P < .05). The combined results for the 5-year and 10-year follow-ups, range of motion, Western Ontario and McMaster University Osteoarthritis Index, complications, and implant revisions showed no significant differences between the porous tantalum and cemented groups.

CONCLUSION

The results of the 5-year and 10-year follow-ups indicate that the use of cementless porous tantalum tibial components is comparable to traditional cemented tibial components, with no significant advantages observed. However, at the 5-year follow-up, the porous tantalum group demonstrated a good bone density in the proximal tibia. Future studies with a larger sample size, long-term clinical follow-up, and radiological results are needed to verify the differences between the 2 implants.

Uncemented trabecular metal high-flex posterior-stabilized monoblock total knee arthroplasty in patients aged 60 years or younger

BACKGROUND

Uncemented trabecular metal (TM) monoblock tibial components in total knee arthroplasty (TKA) have shown excellent clinical results for up to 10 years. However, these studies were performed in highly specialized units, with few surgeons and often excluding knees with secondary osteoarthritis (OA), severe malalignments and previous surgery. The purpose of this study was to investigate implant survivorship and clinical and radiological outcome of the uncemented TM high-flex posterior stabilized (PS) monoblock tibial component in routine clinical practice.

METHODS

A retrospective study of 339 knees (282 patients) operated with the implant in routine clinical practice at two hospitals on patients aged 60 years or younger between 2007 and 2015. The operations were performed by 12 surgeons and there were no specific contraindications for use of the implant. Follow up ended in 2020. The status of the implant of deceased patients at death and those not attending follow up was checked with the Swedish Knee Arthroplasty Register. Clinical follow up consisted of clinical investigation, PROMs, and knee X-ray.

RESULTS

Follow up was mean (range) 8.5 (5-13.8) years, and the 8-year survival rate was 0.98 (standard error 0.007). Five patients five knees) were deceased, five knees were revised (none due to aseptic loosening), and 16 patients did not attend the clinical follow up. Forty-four percent of the knees had secondary OA and 45% had had previous operations. 93% were satisfied or very satisfied with the operation and forgotten joint score (FJS) was median (interquartile range) 81 (44-94). Radiographic analysis revealed bone in close contact with the tibial tray and pegs in most cases, and in only 2% of the knees were potential radiolucent lines found.

CONCLUSION

The results indicate that this uncemented implant performs excellently in routine clinical practice and also in younger patients with secondary OA or previous knee operations.

6-month migration sufficient for evaluation of total knee replacements: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

This updated meta-analysis evaluates the migration pattern of the tibial component of primary total knee replacements measured with radiostereometric analysis (RSA). We aimed to evaluate whether 6-month maximum total point motion (MTPM) values could be used instead of 1-year MTPM for RSA threshold testing and to present the pooled migration patterns for different implant designs that can be used as a benchmark.

PATIENTS AND METHODS

The search included all published RSA studies on migration patterns of tibial components until 2023. Study groups were classified according to their prosthesis brand, fixation, and insert (PFI). Sub-analyses were performed to compare the mean tibial component migration patterns of different implant variables, stratified according to fixation.

RESULTS

96 studies (43 new studies), including 197 study groups and 4,706 knees, were included. Most migration occurred within the first 6 postoperative months (126 study groups: mean 0.58 mm, 95% confidence interval [CI] 0.50-0.65), followed by minimal migration between 6 and 12 months (197 study groups: mean 0.04 mm, CI 0.03-0.06), irrespective of the fixation method used. Distinct migration patterns were observed among the different fixation methods. No differences were found in migration patterns among cemented components in any of the sub-group analyses conducted. For uncemented implants, trabecular metal surfaced components seemed to migrate less than porous-coated or uncoated components Conclusion: Based on the small difference between MTPM values at 6 months and 1 year, MTPM at 6 months could be used instead of MTPM at 1 year for RSA threshold testing. The pooled migration patterns can be used as benchmark for evaluation of new implants by defining fixation-specific RSA thresholds when combined with implant survival.

Outcomes of trabecular metal total ankle replacement: a longitudinal observational cohort study of 239 consecutive cases from the Swedish Ankle Registry

BACKGROUND AND PURPOSE

Information on outcomes after some modern total ankle replacement (TAR) designs is scarce. We therefore examined outcomes after trabecular metal (TM) TAR in Sweden by use of data from the national registry.

PATIENTS AND METHODS

On December 31, 2020, 239 primary TM TARs had been reported to the Swedish Ankle Registry. We analyzed prosthesis survival probability, using exchange or permanent extraction of components as endpoint for 239 protheses with mean follow-up of 2.2 years (0.1-6.6), risk of revision, as well as patient-reported outcome measures (SEFAS/EQ-5D/EQ-VAS) and satisfaction with surgery.

RESULTS

7/239 prostheses (3%) had been revised by December 31, 2020. We found an overall prosthesis survival probability of 95% (95% CI 89-98) after 3 years. 2 years after surgery 81% of the answering patients were satisfied or very satisfied with surgery and patients reported median SEFAS 36 (max 48), EQ-5D 0.90 (max 1), and EQ-VAS 80 (max 100).

INTERPRETATION

We found short- to mid-term outcomes after TM TAR to be at least as good as after other TAR designs regarding prosthesis survival and patient-reported satisfaction.

Total Knee Replacement with an Uncemented Porous Tantalum Tibia Component: A Failure Analysis

Porous tantalum has been extensively used in orthopaedic surgery, including uncemented total knee arthroplasty (TKA). Favourable results were reported with earlier monobloc tibial components and the design evolved to modular implants. We aimed to analyse possible causes for extensive medial tibia bone loss, resulting in modular porous tantalum tibia baseplate fracture after primary TKA. Retrieved tissue samples were scanned with 3 MeV focused proton beam for Proton-Induced X-ray Emission (micro-PIXE) elemental analysis. Fractographic and microstructural analysis were performed by stereomicroscopy. A full 3D finite-element model was made for numerical analysis of stress-strain conditions of the tibial baseplate. Histological examination of tissue underneath the broken part of the tibial baseplate revealed dark-stained metal debris, which was confirmed by micro-PIXE to consist of tantalum and titanium. Fractographic analysis and tensile testing showed that the failure of the tibial baseplate fulfilled the criteria of a typical fatigue fracture. Microstructural analysis of the contact surface revealed signs of bone ingrowth in 22.5% of the surface only and was even less pronounced in the medial half of the tibial baseplate. Further studies are needed to confirm the responsibility of metal debris for an increased bone absorption leading to catastrophic tibial tray failure.

The effect of a novel pillar surface morphology and material composition demonstrates uniform osseointegration

Long-term survival of orthopedic implants requires a strong and compliant interface between the implant and surrounding bone. This paper further explores the in-vivo response to a novel, macro-scale osseointegration surface morphology. In this study, we examine the effects of material composition on osseointegration in relation to the controlled surface geometry. The pillared surface is constructed of discontinuous surface geometry which creates an open space for unencumbered bone migration. In creating an open, macro-scale morphology we have demonstrated a bone migration and integration that is less dependent on the underlying implant material and is substantially driven thru surface geometry. In this in-vivo study an established ovine model was used to examine the effects of implant material composition on bone ingrowth and mechanical performance. Cortical and cancellous sites in the tibia and distal femur were examined at 6 and 12 weeks with μCT, histology, histomorphometry, and mechanical performance. Implant materials tested included PEEK (Evonik, VISTAKEEP®), PEEK HA (Invibio, PEEK-OPTIMA HA Enhanced), Titanium coated PEEK, Titanium (Ti-6Al-4V, Grade 5), and Ultra-High Molecular Weight Polyethylene (UHMWPE). Extensive bone ingrowth was noted in all implant materials at 12 weeks with maturation of the bone within the pillar structure from 6 weeks to 12 weeks. Histology demonstrated little fibrous deposition at the implant interface with no adverse cellular reactions. Histomorphometric review of cortical sites revealed greater than 60% bone ingrowth at 6 weeks increasing to nearly 80% by the 12 week timepoint. Cancellous sites yielded a mean of 30% ingrowth at 6 weeks increasing to 35% by 12 weeks. Pushout testing of cortical site samples demonstrated increase in pushout force between the 6 and 12 week timepoints. Increases were significant in all but the UHMWPE samples. Stiffness likewise increased in all samples between the two times. These results demonstrated the effectiveness of the pillar morphology with full integrating from the surrounding bony tissue regardless of the material.

Titanium alloy cannulated screws and biodegradable magnesium alloy bionic cannulated screws for treatment of femoral neck fractures: a finite element analysis

Background

Cannulated screws (CS) are one of the most widely used treatments for femoral neck fracture, however, associated with high rate of complications. In this study, we designed a new type of cannulated screws called degradable magnesium alloy bionic cannulated screws (DMBCS) and our aim was to compare the biomechanical properties of DMBCS, the traditionally used titanium alloy bionic cannulated screws (TBCS) and titanium alloy cannulated screws (TTCS).

Methods

A proximal femur model was established based on CT data of a lower extremity from a voluntary healthy man. Garden type III femoral neck fracture was constructed and fixed with DMBCS, TBCS, and TTCS, respectively. Biomechanical effect which three type of CS models have on femoral neck fracture was evaluated and compared using von Mises stress distribution and displacement.

Results

In the normal model, the maximum stress value of cortical bone and cancellous bone was 76.18 and 6.82 MPa, and the maximum displacement was 5.52 mm. Under 3 different fracture healing status, the stress peak value of the cortical bone and cancellous bone in the DMBCS fixation model was lower than that in the TTCS and TBCS fixation, while the maximum displacement of DMBCS fixation model was slightly higher than that of TTCS and TBCS fixation models. As the fracture heals, stress peak value of the screws and cortical bone of intact models are decreasing, while stress peak value of cancellous bone is increasing initially and then decreasing.

Conclusions

The DMBCS exhibits the superior biomechanical performance than TTCS and TBCS, whose fixation model is closest to the normal model in stress distribution. DMBCS is expected to reduce the rates of post-operative complications with traditional internal fixation and provide practical guidance for the structural design of CS for clinical applications.

In-Vivo response to a novel pillared surface morphology for osseointegration in an ovine model

Primary stability and secondary fixation of orthopedic implants to bony tissues are important for healing and long-term functionality. Load sharing and stress transfer are key requirements of an effective implant/tissue interface. This paper presents a novel, macro-scale osseointegration surface morphology which addresses the implant/tissue interface from both the biologic as well as biomechanical perspective. The surface morphology is a controlled, engineered, open topography manifested as discrete pillars projecting from the implant enabling continuous bone ingrowth. The pillared surface is distinct from other porous surfaces and can be differentiated by the localization of the implant material into discrete pillars enabling a continuous mass of bone to freely and easily interdigitate into the pillared structure. Traditional porous structures distribute the implant material throughout the surface forcing the bone to grow in a discontinuous manner. Creating an open and continuous space or "open porosity" in and around the pillar structure allows the bone to easily interdigitate with the implant surface without encumberment from a continuous porous structure. An in-vivo study, using an established ovine model, was undertaken examining the effects of pillar morphology on bone ingrowth and mechanical performance. Cortical and cancellous sites were evaluated utilizing histology, histomophometry, and mechanical pushout, at 4 and 12 weeks. Robust bone ingrowth occurred for all morphologies as was noted in review of the study results. An increase in volume and maturity of bone was noted between the intermediated and final time points. Histomophometry demonstrated over 40% and 80% new bone occupied the available "ingrowth" area at 12 weeks for cancellous and cortical sites (respectively). Histologic review showed little fibrous tissue ingrowth at the interface with no adverse cellular reactions. Testing of cortical samples demonstrated a significant increase in pushout load between the 4 and 12 week timepoints and a 4-8 fold increase in pushout load as compared to the grit blast control. These results demonstrated the effectiveness of the novel interface for orthopedic applications in an in-vivo ovine model.

Association between fixation type and revision risk in total knee arthroplasty patients aged 65 years and older: a cohort study of 265,877 patients from the Nordic Arthroplasty Register Association 2000-2016

Background and purpose - The population of the Nordic countries is aging and the number of elderly patients undergoing total knee arthroplasty (TKA) is also expected to increase. Reliable fixation methods are essential to avoid revisions. We compared the survival of different TKA fixation concepts with cemented fixation as the gold standard.Patients and methods - We used data from the Nordic Arthroplasty Register Association (NARA) database of 265,877 unconstrained TKAs performed for patients aged ≥ 65 years with primary knee osteoarthritis between 2000 and 2016. Kaplan-Meier (KM) survival analysis with 95% confidence intervals (CI) and the Cox multiple-regression model were used to compare the revision risk of the fixation methods.Results - Cemented fixation was used in 243,166 cases, uncemented in 8,000, hybrid (uncemented femur with cemented tibia) in 14,248, and inverse hybrid (cemented femur with uncemented tibia) fixation in 463 cases. The 10-year KM survivorship (95% CI) of cemented TKAs was 96% (96 - 97), uncemented 94% (94 - 95), hybrid 96% (96 - 96), and inverse hybrid 96% (94 - 99), respectively. Uncemented TKA was associated with increased risk of revision compared with the cemented TKA; the adjusted hazard ratio was 1.3 (95% CI 1.1 - 1.4).Interpretation - Cemented, hybrid, and inverse hybrid TKAs showed 10-year survival rates exceeding 95%. Uncemented fixation was associated with an increased risk of revision in comparison with cemented fixation. As both hybrid and inverse hybrid fixation were used in only a limited number of TKAs, indicating possibility of selection bias in their favor, cemented TKA still remains the gold standard, as it works reliably in the hands of many.

Primary Stability in Cementless Rotating Platform Total Knee Arthroplasty

Highly porous ingrowth surfaces have been introduced into tibial tray fixation to improve long-term survivorship in cementless total knee arthroplasty. This study was designed to evaluate the effect of porous ingrowth surface on primary stability in the implanted cementless tibial component. Three tibial tray designs possessing sintered bead or roughened porous coating ingrowth surfaces were implanted into a foam tibia model with primary stability assessed via digital image correlation during stair descent and condylar liftoff loading. Follow-up testing was conducted by implanting matched-pair cadaveric tibias with otherwise identical trays with two iterations of ingrowth surface design. Trays were loaded and micromotion evaluated in a condylar liftoff model. The sintered bead tibial tray exhibited slightly lower micromotion than the roughened porous coating in stair descent loading. However, no significant difference in primary stability was observed in condylar liftoff loading in either foam or cadaveric specimens. Cementless tibial trays featuring two different iterations of porous ingrowth surfaces demonstrated both good stability in cadaveric specimens with less than 80 microns of micromotion and 1 mm of subsidence under cyclic loading. While improved ingrowth surfaces may lead to improved biological fixation and long-term osteointegration, this study was unable to identify a difference in primary stability associated with subsequent ingrown surface design iteration.

Midterm Comparison of Tibial Fixation between Posterior Cruciate-Retaining and Substituting Porous Tantalum Total Knee Arthroplasty: Three-Dimensional Computed Tomography Analysis

Porous tantalum tibial component is durable with excellent bone ingrowth, higher knee scores, and long-term survivorship. However, to our knowledge, the effect of posterior cruciate-retaining (CR) and posterior cruciate-substituting (PS) porous tantalum tibial component has not been reported. The aim of the current study was to investigate the prosthetic bone quality between CR porous tantalum tibial component and PS using three-dimensional multi-detector-row computed tomography (3D-MDCT). Porous twenty-two (22) CR total knee arthroplasties and 22 PS received 3D-MDCT at every 6 months up to 5.5 years postoperatively to assess prosthetic bone quality (bone marrow contents/tissue volumes [BMC/TV, mg/cm³]) underneath the pegs of porous tantalum modular tibial component. Clinical outcomes (Knee Society score [KSS], Western Ontario and McMaster Universities (WOMAC), FJS-12, Patella score) were evaluated at a minimum follow-up period of 5.5 years. No statistically significant differences were found in age, gender, body mass index, KSS, and BMC/TV volumes in the proximal tibia between the two groups before total knee arthroplasty (TKA). There were also no significant differences between the CR and PS groups with regard to BMC/TV at every 6 months up to 5.5 years after TKA. At 5.5 years postoperatively, there was no significant difference between the two groups in terms of the KSS, WOMAC, forgotten joint score (FJS-12), and Patella score. The present study revealed that the prosthetic bone quality of the CR porous tantalum tibial component and PS were equivalent at every 6 months up to 5.5 years after TKA. This study reflects level II evidence.

Clinical Outcomes and Survivorship of Contemporary Cementless Primary Total Knee Arthroplasties

BACKGROUND

Total knee arthroplasties (TKAs) with cementless fixation have been studied in multiple series with varying success. The aim of this study was to prepare a systematic review of the literature to evaluate clinical outcomes and revtpdelision rates of patients undergoing contemporary cementless TKA.

METHODS

A search of PubMed and MEDLINE was conducted for English-language articles published between 2005 and 2018 to identify studies examining survivorship and clinical outcomes of cementless TKAs. Studies that reported clinical and/or radiographic outcomes were included. Data collected included the number of TKAs, implant utilized, primary diagnosis, mean age and follow-up, implant survivorship, complications, revisions, and clinical outcome scores. All hybrid constructs and revision TKAs were excluded. Poisson regression analysis was used to determine the revision incidence rates per 1,000 person-years.

RESULTS

Forty-three studies with 10,447 TKAs met inclusion criteria, of which 8,187 were primary cementless TKAs. The mean follow-up was 7 years. The revision incidence per 1,000 person-years was 4.8 for all cementless designs. The complication rate for all cementless TKAs was 6%, with deep venous thrombosis being the most common complication. The mean postoperative Knee Society Score and Functional Score were 92 and 83, respectively.

CONCLUSIONS

While newer-generation cementless designs have shown improved survivorship and clinical outcomes compared with earlier-generation cementless designs, the literature for cementless designs remains limited when compared with cemented designs. Further studies are needed to determine if cementless TKA can achieve the same benefits that have been realized with cementless total hip arthroplasty.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Uncemented tantalum metal components versus cemented tibial components in total knee arthroplasty: 11- to 15-year outcomes of a single-blinded randomized controlled trial

Aims

Total knee arthroplasty is an established treatment for knee osteoarthritis with excellent long-term results, but there remains controversy about the role of uncemented prostheses. We present the long-term results of a randomized trial comparing an uncemented tantalum metal tibial component with a conventional cemented component of the same implant design.

Methods

Patients under the age of 70 years with symptomatic osteoarthritis of the knee were randomized to receive either an uncemented tantalum metal tibial monoblock component or a standard cemented modular component. The mean age at time of recruitment to the study was 63 years (50 to 70), 46 (51.1%) knees were in male patients, and the mean body mass index was 30.4 kg/m2 (21 to 36). The same cruciate retaining total knee system was used in both groups. All patients received an uncemented femoral component and no patients had their patella resurfaced. Patient outcomes were assessed preoperatively and postoperatively using the modified Oxford Knee Score, Knee Society Score, and 12-Item Short-Form Health Survey questionnaire (SF-12) score. Radiographs were analyzed using the American Knee Society Radiograph Evaluation score. Operative complications, reoperations, or revision surgery were recorded. A total of 90 knees were randomized and at last review 77 knees were assessed. In all, 11 patients had died and two were lost to follow-up.

Results

At final review all patients were between 11 and 15 years following surgery. In total, 41 of the knees were cemented and 36 uncemented. There were no revisions in the cemented group and one revision in the uncemented group for fracture. The uncemented group reported better outcomes with both statistically and clinically significant (p = 0.001) improvements in knee-specific Oxford and Knee Society scores compared with the cemented group. The global SF-12 scores demonstrated no statistical difference (p = 0.812). Uncemented knees had better radiological analysis compared with the cemented group (p < 0.001)

Conclusion

Use of an uncemented trabecular metal tibial implant can afford better long-term clinical outcomes when compared to cemented tibial components of a matched design. However, both have excellent survivorship up to 15 years after implantation. Cite this article: Bone Joint J 2020;102-B(8):1025–1032.

The effect of fixation type on the survivorship of contemporary total knee arthroplasty in patients younger than 65 years of age: a register-based study of 115,177 knees in the Nordic Arthroplasty Register Association (NARA) 2000-2016

Background and purpose - Cemented fixation is regarded as the gold standard in total knee arthroplasty (TKA). Among working-age patients, there has been controversy regarding the optimal fixation method in TKA. To address this issue, we conducted a register-based study to assess the survivorship of cemented, uncemented, hybrid, and inverse hybrid TKAs in patients aged < 65 years.Patients and methods - We used the Nordic Arthroplasty Register Association data of 115,177 unconstrained TKAs performed for patients aged < 65 years with primary knee osteoarthritis over 2000-2016. Kaplan-Meier (KM) survival analysis with 95% confidence intervals (CI) and Cox multiple-regression model with adjustment for age, sex, and nation were used to compare fixation methods in relation to revision for any reason.Results - The 10-year KM survivorship of cemented TKAs was 93.6% (95% CI 93.4-93.8), uncemented 91.2% (CI 90.1-92.2), hybrid 93.0% (Cl 92.2-93.8), and inverse hybrid 96.0% (CI 94.1-98.1). In the Cox model, hybrid TKA showed decreased risk of revision after 6 years' follow-up compared with the reference group (cemented) (hazard ratio [HR] 0.5 [CI 0.4-0.8]), while uncemented TKAs showed increased risk of revision both < 1 year (HR 1.4 [1.1-1.7]) and > 6 years' (HR 1.3 [1.0-1.7]) follow-up compared to the reference.Interpretation - Both cemented and hybrid TKAs had 10-year survival rates exceeding 92->93% in patients aged < 65 years. Cemented TKA, however, was used in the vast majority (89%) of the operations in the current study. As it performs reliably in the hands of many, it still deserves the status of gold standard for TKA in working-age patients.

Catastrophic tibial baseplate failure of a modern cementless total knee arthroplasty implant

Tibial baseplate fracture following primary total knee arthroplasty is a rare complication, particularly with modern implants and surgical techniques. This case details the first known report of mid-range follow-up catastrophic failure of a cementless modular, trabecular metal tibial baseplate. This failure highlights the importance of continued follow-up for novel implants, to include cementless knee arthroplasty designs, particularly if new symptoms arise or periarticular bone loss is identified on radiograph.

Use of porous monoblock patella component should avoid for patient with patella baja

Background

Although many studies have evaluated the success of porous tantalum component in primary and revision cementless total knee arthroplasty (TKA) cases, few studies have reported the breakage of porous tantalum monoblock patella component (PTMP). The purpose of this study was to investigate the radiographic outcomes of breakage of PTMP at short-term follow up.

Methods

This was a retrospective study of 49 consecutive knees in 43 patients who underwent TKA surgery between September 2012 and March 2014. Bone marrow contents/tissue volumes (BMC/TV. mg/cm³) were evaluated using 2-dimensional osteomorphometry software with 2D- multi-detector-row computed tomography (2D-MDCT) to measure fixation of the bone-prosthesis interface with patella at 6, 12, and 24 months after surgery. Clinical follow up was obtained by reviewing each patient at orthopedic record.

Results

We experienced a case that resulted in breakage of PTMP without traumatic episode at 26 months after surgery. Relative changes of Bone Mineral Contents per Tissue Volume. (BMC/TV mg/cm³) at ROI. 1 (superior border of the patella) and ROI. 2 (peg of patella) were significantly higher than ROI.3 (inferior border of patella) at 6, 12 and 24 months after surgery (p < 0.001. p < 0.01). Patient with breakage of PTMP has patella baja (Insall- Salvati ratio: 0.72), and the relative change of BMC/TV at ROI.1 and 2 for patients who experienced a breakage of PTMP was higher than any other patients.

Conclusion

The present study revealed that the use of PTMP should be avoided for patients with patella baja.

Radiolucent lines are decreased at 3 years following total knee arthroplasty using trabecular metal tibial components

Objective To analyse location and frequency, and change over time, of radiolucent lines (RLLs) around trabecular metal tibial components in total knee arthroplasty (TKA). Methods Osteoarthritic knees in patients who had undergone TKA were retrospectively evaluated via analysis of RLLs on anteroposterior and lateral X-rays obtained at 2 and 6 months, and 1, 2 and 3 years following TKA. Results In 125 osteoarthritic knees from 90 patients (mean age, 75.0 ± 6.2; 21 male/69 female), frequency of RLLs around trabecular metal tibial components was generally highest at 2 and 6 months, and 1 year following TKA, then gradually decreased over the 3-year follow-up. Frequency of RLLs around trabecular metal tibial components was greater at the tip of the two pegs, particularly the medial peg, and around the pegs, versus other zones. No postoperative revisions were performed for loosening. Conclusions Over 3 years following TKA, RLLs were most frequently observed up to 1 year, then gradually decreased. RLLs were significantly more frequent in the medial peg zone and zones close to the medial peg than in other zones.

Uncemented Metal-Backed Tantalum Patellar Components in Total Knee Arthroplasty Have a High Fracture Rate at Midterm Follow-Up

BACKGROUND

There is interest in uncemented total knee arthroplasty due to the hope for long-term biologic fixation, but limited data are available regarding uncemented tantalum patellar components. The purpose of this study was to evaluate the radiographic outcomes of uncemented tantalum patellar implants at midterm follow-up.

METHODS

We retrospectively reviewed a consecutive series of 30 knees in 29 patients who underwent cementless total knee arthroplasty with an uncemented metal-backed tantalum patella between September 2006 and April 2009. Patients were required to have a minimum radiographic follow-up of 2 years. Anteroposterior and lateral radiographs of the knee were evaluated for signs of implant fracture or gross loosening. Clinical follow-up was obtained by reviewing each patient's most recent orthopedic record.

RESULTS

Thirty knees in 29 patients met inclusion criteria. The mean age of the cohort was 59.1 years with a mean body mass index of 31.9 kg/m². Mean postoperative radiographic follow-up time was 5.5 years. Six fractures of the patellar component were noted. This represented a fracture rate of 20% among the entire cohort and 35% among the 17 knees with visible patellae on anteroposterior radiograph. All fractures had a transverse pattern. No gross patellar component loosening was noted. Among patients with component fractures, 2 required revisions for instability and 1 revision was for infection.

CONCLUSION

Our results suggest a minimum 20% rate of component fracture at midterm follow-up. Although many of these patellar component fractures were asymptomatic, they have the potential to impact revision rates in the longer term.

Outcomes of cementless unicompartmental and total knee arthroplasty: A systematic review

BACKGROUND

Aseptic loosening is a common failure mode in cemented unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). This led to the development of cementless designs but the historical outcomes were poor. Recent developments in cementless designs have improved outcomes, but the current status is unknown. Therefore, a systematic review was performed to assess recent outcomes of cementless knee arthroplasty.

METHODS

A search was performed using PubMed, Embase and Cochrane systems and national registries for studies reporting outcomes since 2005. Fifty-two cohort studies and four registries reported survivorship, failure modes or functional outcomes of cementless UKA and TKA.

RESULTS

Nine level I studies, six level II studies, three level III studies, 34 level IV studies and four registries were included. Three hundred eighteen failures in 10,309 cementless TKA procedures and 62 failures in 2218 cementless UKA procedures resulted in extrapolated five-year, 10-year and 15-year survivorship of cementless TKAs of 97.7%, 95.4% and 93.0%, respectively, and cementless UKA of 96.4%, 92.9% and 89.3%, respectively. Aseptic loosening was more common in cementless TKA (25%) when compared to UKA (13%). Functional outcomes of cementless TKA and UKA were excellent with 84.3% and 84.5% of the maximum possible scores, respectively.

CONCLUSIONS

This systematic review showed that good to excellent extrapolated survivorship and functional outcomes are seen following modern cementless UKA and TKA, with a low incidence of aseptic loosening following cementless UKA.

LEVEL OF EVIDENCE

Level IV.

Cementless vs Cemented Tibial Fixation in Primary Total Knee Arthroplasty

BACKGROUND

The ideal fixation for modern tibial components in total knee arthroplasty (TKA) remains controversial with uncertainty on whether cementless implants can yield equivalent outcomes to cemented fixation in early follow-up.

METHODS

A series of 70 consecutive cases with reverse hybrid cementless fixation were matched to 70 cemented cases from 2008 to 2015 based on implant design and patient demographics.

RESULTS

Cementless TKA demonstrated greater aseptic loosening (7 vs 0, P = .013) and revision surgery (10 vs 0, P = .001) than cemented fixation within 5 years of follow-up, but with no clinically significant differences in outcome scores.

CONCLUSION

It remains unclear whether early aseptic loosening in cementless TKA can be reduced with enhanced adjunct fixation and what proportion of early failure justifies the potential lifelong fixation through biologic ingrowth of cementless tibial components.

Long-term results of a porous tantalum monoblock tibia component: clinical and radiographic results at follow-up of 10 years

Background

The purpose of this study is to assess the long-term follow-up of cementless total knee arthroplasty with the trabecular metal (TM) monoblock tibial component at an average 10-year follow-up. This report is an extension of our previously reported series of 108 TM tibias reported in 2011 (Unger and Duggan, 2011).

Methods

Fifty-eight of the original 108 knees were available for review. Each follow-up patient was evaluated by radiologic and clinical Knee Society Scores. The average follow-up was 10.2 years.

Results

Our results indicate excellent long-term survivorship (96.5%) with 2 confirmed tibia revisions, and 1 femoral revision for periprosthetic fracture and 1 patella open reduction internal fixation. X-ray evaluation demonstrated one patient with 1 mm medial polyethylene wear and a nonprogressive 1 mm of radiolucency on the medial side. All the other tibial components showed full bone apposition and incorporation. Knee Society Scores were excellent in all the patients seen on follow-up.

Conclusions

Long-term follow-up of TM monoblock tibia components confirm excellent survivorship and biologic implant fixation, with excellent outcomes and knee scores.

Annual revision rates of partial versus total knee arthroplasty: A comparative meta-analysis

BACKGROUND

Utilization of unicompartmental knee arthroplasty (UKA) and patellofemoral arthroplasty (PFA) as alternatives to total knee arthroplasty (TKA) for unicompartmental knee osteoarthritis (OA) has increased. However, no single resource consolidates survivorship data between TKA and partial resurfacing options for each variant of unicompartmental OA. This meta-analysis compared survivorship between TKA and medial UKA (MUKA), lateral UKA (LUKA) and PFA using annual revision rate as a standardized metric.

METHODS

A systematic literature search was performed for studies quantifying TKA, MUKA, LUKA and/or PFA implant survivorship. Studies were classified by evidence level and assessed for bias using the MINORS and PEDro instruments. Annual revision rates were calculated for each arthroplasty procedure as percentages/observed component-year, based on a Poisson-normal model with random effects using the R-statistical software package.

RESULTS

One hundred and twenty-four studies (113 cohort and 11 registry-based studies) met inclusion/exclusion criteria, providing data for 374,934 arthroplasties and 14,991 revisions. The overall evidence level was low, with 96.7% of studies classified as level III-IV. Annual revision rates were lowest for TKA (0.49%, CI 0.41 to 0.58), followed by MUKA (1.07%, CI 0.87 to 1.31), LUKA (1.13%, CI 0.69 to 1.83) and PFA (1.75%, CI 1.19 to 2.57). No difference was detected between revision rates for MUKA and LUKA (p=0.222).

CONCLUSIONS

Revisions of MUKA, LUKA and PFA occur at an annual rate of 2.18, 2.31 and 3.57-fold that of TKA, respectively. These estimates may be used to inform clinical decision-making, guide patient expectations and evaluate the cost-effectiveness of total versus partial knee replacement in the setting of unicompartmental OA.

Cementless Porous Tantalum Monoblock Tibia vs Cemented Modular Tibia in Primary Total Knee Arthroplasty: A Meta-Analysis

BACKGROUND

With the introduction of new fixation systems and designs, there has been a recent reemergence of interest in cementless fixation of the tibial component in total knee arthroplasty. However, little is known regarding the clinical features and survivorship of the cementless porous tantalum monoblock tibial component compared to the conventional cemented modular tibial component.

METHODS

We conducted a literature search of multiple databases for comparative studies published before June 2015 that investigated the outcomes of cementless porous tantalum monoblock tibia vs conventional cemented modular tibia. A pooled analysis was performed. The outcomes of interest were postoperative functional score, range of motion, Western Ontario and McMaster University Osteoarthritis Index, total complications, reoperation, radiolucent lines, loosening of the tibial component, and length of operation.

RESULTS

Six studies involving 977 patients were eligible for the meta-analysis. The use of a cementless porous tantalum monoblock tibial component may associate with a slightly higher functional score, fewer radiolucent lines, and shorter operation. No significant difference was seen in regard to the range of motion, Western Ontario and McMaster University Osteoarthritis Index, total complications, reoperation, and loosening of the component between the 2 groups.

CONCLUSION

However, due to variation among the included studies, the use of cementless porous tantalum monoblock tibia seems to achieve no substantial superiority over that of the conventional cemented modular tibia at 5-year follow-up. Data concerning the long-term prognosis of this novel implant should continue to be collected and analyzed.

Total Knee Arthroplasty Using Cementless Porous Tantalum Monoblock Tibial Component: A Minimum 10-Year Follow-Up

BACKGROUND

Cementless fixation in total knee arthroplasty (TKA) was introduced to improve the longevity of implants but has yet to be widely adopted because of reports of higher failure rates in some series. The cementless tantalum monoblock tibial component, in contrast, has shown successful short-term results, but long-term survivorship with this design is still lacking. The purpose of this study was to investigate the minimum 10-year clinical and radiographic results of the cementless tantalum monoblock tibial component in primary TKA.

METHODS

From March 2002 to March 2005, 33 patients (33 knees) underwent primary TKA with a cementless tantalum monoblock tibial component. All patients were followed clinically and radiographically for a minimum of 10 years (mean 11.5 years, range 10-13 years). No patients were lost to follow-up. The underlying diagnosis that led to the primary TKA was primary osteoarthritis in 31 knees and post-traumatic osteoarthritis in 2 knees.

RESULTS

None of the components was revised. At a minimum 10-year follow-up, the survivorship with reoperation for any reason as end point was 96.9%. With tibial component revision for aseptic loosening or osteolysis as the end point survivorship was 100%. There was no radiographic evidence of tibial component loosening, subsidence, osteolysis, or migration at the time of the latest follow-up. The mean Knee Society knee scores improved from 56 points preoperatively to 93 points at the last clinical visit.

CONCLUSION

The porous tantalum tibial monoblock component demonstrated excellent clinical and radiographic outcomes with no component revisions for aseptic loosening at a minimum follow-up of 10 years.

Trabecular metal tibial knee component still stable at 10 years

Background and purpose - Total knee replacement (TKR) in younger patients using cemented components has shown inferior results, mainly due to aseptic loosening. Excellent clinical results have been reported with components made of trabecular metal (TM). In a previous report, we have shown stabilization of the TM tibial implants for up to 5 years. In this study, we compared the clinical and RSA results of these uncemented implants with those of cemented implants. Patients and methods - 41 patients (47 knees) aged ≤ 60 years underwent TKR. 22 patients (26 knees) received an uncemented monoblock cruciate-retaining (CR) tibial component (TM) and 19 patients (21 knees) received a cemented NexGen Option CR tibial component. Follow-up examination was done at 10 years, and 16 patients (19 knees) with TM tibial components and 17 patients (18 knees) with cemented tibial components remained for analysis. Results - 1 of 19 TM implants was revised for infection, 2 of 18 cemented components were revised for knee instability, and no revisions were done for loosening. Both types of tibial components migrated in the first 3 months, the TM group to a greater extent than the cemented group. After 3 months, both groups were stable during the next 10 years. Interpretation - The patterns of migration for uncemented TM implants and cemented tibial implants over the first 10 years indicate that they have a good long-term prognosis regarding fixation.

Early Debris Formation with a Porous Tantalum Glenoid Component: Radiographic Analysis with 2-Year Minimum Follow-up

BACKGROUND

Porous tantalum has been used effectively in hip, knee, and reverse shoulder arthroplasty implants. However, a first-generation porous tantalum glenoid component for use in anatomic shoulder arthroplasty previously demonstrated failure, with failure usually preceded by the appearance of intra-articular metallic debris. After redesign, the component was reintroduced in 2009. The purpose of the current study was to evaluate the radiographic and clinical outcomes of the redesigned glenoid component.

METHODS

Sixty-eight patients undergoing total shoulder arthroplasty received a Trabecular Metal porous tantalum glenoid component (73 components; 5 patients underwent staged bilateral procedures). No polymethylmethacrylate cement was used (off-label usage in the U.S.). A grading system to assess metallic debris formation was developed using radiographs of the previous generation of porous tantalum glenoid components that failed. Radiographs from the current series were independently reviewed by 2 shoulder arthroplasty specialists, and their results were compared. Glenoid components were evaluated for signs of bone ingrowth and metallic debris formation.

RESULTS

Sixty-six (90%) of the 73 components were evaluated at a minimum of 2 years of follow-up (mean radiographic follow-up of 50.8 months; range, 24 to 68 months). Of these, 92.4% demonstrated minimal or no glenoid radiolucency. Overall, the prevalence of metallic tantalum debris formation was 44% (29 of 66). Sequential radiograph review demonstrated that the incidence of metallic debris formation increased for each year of follow-up, with radiographs from 2, 3, 4, and ≥5 years of follow-up demonstrating a metallic debris incidence of 23%, 36%, 49%, and 52%, respectively. Additionally, the severity of metallic debris formation increased with follow-up duration. There was no component dissociation or revision due to implant breakage in this series.

CONCLUSIONS

The porous tantalum glenoid component studied had excellent short-term component fixation. However, the development of metallic debris, increasing in both overall incidence and degree of severity over time, raises concern for potential failure of this glenoid component. Longer follow-up is required.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Is There A Difference in Bone Ingrowth in Modular Versus Monoblock Porous Tantalum Tibial Trays?

Contemporary total knee designs incorporating highly porous metallic surfaces have demonstrated promising clinical outcomes. However, stiffness differences between modular and monoblock porous tantalum tibial trays may affect bone ingrowth. This study investigated effect of implant design, spatial location and clinical factors on bone ingrowth. Three modular and twenty-one monoblock retrieved porous tantalum tibial trays were evaluated for bone ingrowth. Nonparametric statistical tests were used to investigate differences in bone ingrowth by implant design, tray spatial location, substrate depth and clinical factors. Modular trays (5.3 ± 3.2%) exhibited higher bone ingrowth than monoblock trays (1.6 ± 1.9%, P = 0.032). Bone ingrowth in both designs was highest in the initial 500 μm from the surface. Implantation time was positively correlated with bone ingrowth for monoblock trays.

The Mark Coventry Award: Trabecular metal tibial components were durable and reliable in primary total knee arthroplasty: a randomized clinical trial

BACKGROUND

Although highly porous metals have demonstrated excellent bone ingrowth properties and so are an intriguing option for fixation in total knee arthroplasty (TKA), some surgeons are skeptical about the durability of uncemented tibial fixation and the potential for soft tissues to adhere to these porous metals and perhaps cause knee stiffness or pain.

QUESTIONS/PURPOSES

The purpose of this study was to compare, in the context of a randomized clinical trial, a highly porous metal tibia compared with a traditional modular cemented tibia in terms of survivorship, Knee Society scores, range of motion (ROM), and complications.

METHODS

From 2003 to 2006, 397 patients (age 67.8 ± 8.7 years; 54% female) were randomized to three groups: (1) traditional modular cemented tibia; (2) cemented highly porous metal tibia; and (3) uncemented highly porous metal tibia. The same posterior-stabilized femoral component and patella component were cemented in every case. Stratified randomization was done for surgeon, patient's age, sex, and body mass index. Survivorship at 5 years was compared between the groups, as were Knee Society scores, ROM, and complications. Radiographic assessment included alignment, radiolucency, and implant migration/loosening. Patients were followed until death, revision, or for a minimum of 2 years (mean, 5 years; range, 2-9 years). Four patients were lost to followup before 2 years.

RESULTS

Highly porous metal tibias (both uncemented and cemented) were no different from traditional cemented modular tibial modular components in terms of survivorship at 5 years using a intention-to-treat analysis (96.8% [1]; 97.6% [2]; 96.7% [3]; p = 0.59). A per-protocol analysis revealed that no highly porous metal tibia was revised for aseptic loosening. Highly porous metal tibias performed comparably to traditional cemented modular tibias in terms of Knee Society scores, ROM, and the frequency of complications.

CONCLUSIONS

At 5 years this randomized clinical trial demonstrated that highly porous metal tibias provided comparably durable fixation and reliable pain relief and restoration of function when compared with a traditional cemented modular tibia in TKA.

LEVEL OF EVIDENCE

Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.