Clinical Outcomes and Survivorship of Contemporary Cementless Primary Total Knee Arthroplasties

Finite element analysis of primary stability in cementless tibial components with varying interference fits

BACKGROUND

Cementless knee implants achieve initial fixation through an interference fit, where the tibial implant is press-fitted into an undersized bone cavity. The dimensions between the implant and bone cuts must be carefully balanced to achieve an optimal interference fit, ensuring good primary stability, which is crucial for long-term fixation and successful osseointegration. However, the ideal interference fit remains uncertain. Excessive interference fit may lead to bone plastic deformation, while insufficient fit can result in large micromotions, small movements at the bone-implant interface, that compromise stability. This study evaluates how interference fit affects bone plasticity and micromotions, and how different loading conditions influence primary stability using finite element analysis.

METHODS

Finite element models, based on experimentally implanted components, simulated interference fits of 350 μm and 700 μm. Micromotions, gap dynamics, and bone deformation were assessed during gait and squat activities under both simplified and complex loading conditions.

FINDINGS

Higher interference fits increased bone plastic deformation, limiting elastic energy accumulation, whereas lower interference fits exhibited a reduced effect. Micromotions and gaps were consistently larger in lower interference fit implants. Furthermore, simplified loading underestimated micromotions and gaps compared to the complex loading.

INTERPRETATION

These findings help explain why higher interference fits provided limited improvements in primary stability during experimental tests, despite differing predictions from simulations. This study enhances our understanding of bone-implant interactions and suggests that increasing interference fit does not necessarily improve implant stability. It also highlights the importance of incorporating complex loading conditions for more accurate primary stability assessment.

No difference in 5-year survivorship between cemented versus cementless total knee arthroplasty in a cohort of 5266 patients using a deep-dish mobile bearing implant

PURPOSE

The best fixation method for total knee arthroplasty (TKA) remains controversial. The aim of this study is to compare the effect of cemented and cementless fixation on prosthesis survivorship. Our primary hypothesis is that there is no difference in survivorship between cemented and cementless TKA. Our secondary hypothesis is that there is no difference in aseptic revisions and functional outcomes between cemented and cementless TKA at mid-term follow-up.

METHODS

A multicentre retrospective study was done using data collected prospectively in a large cohort. The same deep-dish mobile bearing design was used for both cemented and cementless TKA. Patients were divided into two groups according to the fixation method. The survival rate between cemented and cementless TKA was compared. Functional outcomes were collected preoperatively and at the 5-year follow-up.

RESULTS

Of the 5266 primary TKA included, 4549 were cementless, and 717 were cemented. At 5 years, there was no significant difference between the survivorship of the cementless (98.7% [95% confidence interval, CI: 98.2-99.1]) and cemented TKA (97.6%, [95% CI: 94.1-99.1]) (p = 0.468). There was no significant difference in the surgery-free survival at 5 years between cementless (95.8% [95% CI: 94.9-96.5]) and cemented TKA (95.5% [95% CI: 92.1-97.5]) (p = 0.508) as well as in aseptic revision: cementless (96.9% [95% CI: 96.2-97.5]) and cemented TKA (97.5 [95% CI: 95.5-98.6]) (p = 0.355). There was no significant difference in the functional outcomes at 5 years.

CONCLUSION

There was no observed difference in survivorship between cemented and cementless TKA at 5 years in this cohort of 5266 patients. Additionally, rates of reoperation and aseptic revision were similar across both fixation methods, and clinical outcomes did not differ significantly. Therefore, it may be suggested that cementless fixation is a safe option for primary TKA.

LEVEL OF EVIDENCE

Level III.

Risk of Early Manipulation in Cemented Versus Cementless Total Knee Arthroplasty: An Analysis of the American Joint Replacement Registry

BACKGROUND

Cementless total knee arthroplasty (TKA) has recently regained popularity, yet data has raised concerns about rates of arthrofibrosis following these procedures. The purpose of this study was to utilize the American Joint Replacement Registry to compare rates of early manipulation under anesthesia (MUA) in cementless and cemented primary TKAs that use technology or manual instrumentation.

METHODS

We queried the American Joint Replacement Registry for all patients ages 18 to 95 years who underwent cemented or cementless primary TKA over a 7-year period. Patients were stratified based on whether technology (robotics or computer-assisted navigation) was used during the primary surgery. Groups were then compared for rates of MUA within 90-day of the index surgery using multivariable logistic regression models. A total of 340,841 cases were included in the study, 78,397 (23%) of which used technology and 262,444 (77%) which did not. Within the technology cohort, there were 51,500 (65%) robotic and 26,897 (35%) navigated cases. There were 65% of technology-assisted TKAs and 92% of manual TKAs cemented.

RESULTS

In the technology group, multivariable analysis demonstrated significantly higher odds of MUA in cemented TKAs compared to cementless (odds ratio [OR] 1.95, 95% confidence interval [CI] [1.06 to 3.59]; P = 0.031). Robotic cases had significantly higher odds of MUA with cemented compared to cementless implants (OR 2.38, 95% CI [1.27 to 4.46]; P = 0.007), while there was no difference in MUA related to cementation in the navigated cases (OR 3.53, 95% CI [0.48 to 25.95]; P = 0.22). In the manual group, there were no significant differences in MUA rates related to cementation use (OR 1.14, 95% CI [0.8 to 1.64]; P = 0.46).

CONCLUSIONS

Cementless TKA did not increase odds of MUA. In further analyzing cement use into technology and manual cohorts, robotic-assisted cemented TKAs had higher rates of early MUA than cementless. Identification of risk factors leading to early arthrofibrosis may be patient dependent and further study is required to elucidate any surgical considerations.

Osteoporosis May Not Be an Absolute Contraindication for Cementless Total Knee Arthroplasty

BACKGROUND

Cementless total knee arthroplasty (TKA) has received growing interest, particularly in younger populations, due to potential long-term survivability and improved bone preservation. Poor bone stock, as seen in osteoporosis, is considered a contraindication for this technique. This study evaluated whether osteoporotic patients < 75 years undergoing cementless TKA demonstrate similar: 1) implant-related complications, 2) medical complications, 3) readmission rates, and 4) 3-year implant survivability.

METHODS

A retrospective query of a national administrative claims database was performed between 2010 and 2022 for patients less than or equal to 75 years old who have osteoporosis and underwent primary TKA. Osteoporotic patients were divided into cementless and cemented cohorts, and propensity scores were matched based on age, sex, obesity, and the Charlson Comorbidity Index. Matching produced 7,923 patients (1,321 uncemented, 6,602 cemented). Multivariate logistic regressions evaluated the following outcomes: 90-day and 2-year implant-related complications, 90-day postoperative medical complications, and 90-day readmissions. Kaplan-Meier survival analysis was conducted to assess 3-year all-cause revision implant survivability. The significance threshold was set to P < 0.01 to minimize type 1 bias.

RESULTS

There were no statistically significant differences in implant-related complications, medical complications, readmissions, and lengths of stay between cementless and cemented TKA groups. Kaplan-Meier analysis demonstrated statistically similar 3-year survivability between cohorts (cemented: 97.6%, confidence interval 96.6 to 98.5; cementless: 97.2%, confidence interval 96.7 to 97.7; P = 0.472).

CONCLUSIONS

Patients who have osteoporosis have equivalent medical and implant-related complications as well as 3-year implant survival following cementless TKA compared with a cemented technique. Our results support cementless TKA as a viable option for patients < 75 years, regardless of prior diagnosis of osteoporosis. Intraoperative decisions regarding bone quality are still necessary to discriminate between those who are candidates for cementless TKA with those who are not.

LEVEL OF EVIDENCE

Level III, Retrospective cohort study.

Early Aseptic Tibial Loosening Is a Concern With a Modern Two-Peg Cementless Total Knee Arthroplasty Design

BACKGROUND

While early generations of cementless total knee arthroplasty (TKA) had inferior outcomes compared to cemented TKA, modern cementless designs have offered excellent clinical results. The purpose of this study was to compare patient-reported outcome measures (PROMs) and early aseptic revision rates of a specific cementless TKA design featuring a two-pegged tibia to that of its cemented counterpart.

METHODS

A retrospective case series of all cementless and cemented TKAs utilizing a single design performed at a single, high-volume academic center was performed. Institutional review board approval was obtained. All cases were performed between November 2018 and March 2022. A minimum one-year follow-up was required. Demographics, complications, and reoperation/revision data were collected. Oxford Knee Score and Forgotten Joint Score were collected at one-year follow-up. Radiographic review was performed for cementless TKAs that were revised or had PROMs < one SD ("poor performers") or had PROMs > one SD ("high performers") below or above the mean, respectively.

RESULTS

There were 329 cementless and 349 cemented TKAs included. Mean follow-up was 1.9 and 2.6 years for cementless and cemented cohorts, respectively. There were no statistical PROM differences between the two cohorts. There was no statistical difference in aseptic revision rates between the cohorts (4.0% cementless versus 1.7% cemented, P = 0.078); however, there was a higher rate of tibial aseptic loosening in the cementless cohort (2.7% cementless versus 0% cemented, P = 0.002). The mean time to revision for aseptic tibial loosening was 17.6 months. There was no statistical difference in radiolucencies between "poor performers" and "high performers."

CONCLUSIONS

When compared to its cemented counterpart, the cementless TKA that was reintroduced in 2018 had similar one-year PROMs but a higher rate of early tibial loosening (2.7 versus 0.0%, P = 0.002).

LEVEL OF EVIDENCE

III.

Survivorship of Modern Cementless Total Knee Arthroplasty: Analysis From the Canadian Joint Replacement Registry

BACKGROUND

Cementless total knee arthroplasty (TKA) is rising in popularity. The literature supporting its use over cemented TKA remains sparse. Using the Canadian Joint Replacement Registry (CJRR), we sought to investigate cementless versus cemented fixation in modern primary TKA and (1) determine whether there is an overall difference in revision by fixation, (2) perform a subanalysis of the most-commonly used cementless TKA brand in Canada, and (3) identify the reasons for revision.

METHODS

The CJRR data was used to analyze TKA designs with cemented and cementless versions. Revision risk is reported as all-cause cumulative percent revision (CPR). Reasons for revision were analyzed. Cox proportional hazards models were used to report adjusted hazard ratios (HR) controlling for age, sex, patella resurfacing, and bearing constraints. We included 202,880 primary TKAs performed between 2012 and 2021. Of those, 9,163 (4.5%) were cementless.

RESULTS

The CPR at 8 years was 4.49% for cementless and 3.14% for cemented implants. After adjusting for confounders, we did not detect a difference in revision risk overall (HR 0.87 [95% CI (confidence interval) 0.73 to 1.04], P = 0.128). However, the most commonly used cementless TKA brand demonstrated a CPR of 1.95% compared to 2.19% for its cemented version at 4 years. Furthermore, we detected a significantly lower revision risk compared to its cemented version after adjusting for confounders (HR 0.66 [95% CI 0.51 to 0.85], P = 0.001). The 4 most common reasons for revision in both groups were the following: (1) infection, (2) instability, (3) aseptic loosening, and (4) pain of unknown origin.

CONCLUSIONS

Using CJRR data adjusted for confounding factors, no difference in revision risk was detected between cemented and cementless implants overall. However, for the most common brand of cementless TKA used in Canada, there was a lower risk of revision than its corresponding cemented version. The reasons for revision were similar.

Tibial Baseplate Microstructure Governs High Cycle Fatigue Fracture In Vivo

Previous studies report rare occurrences of tibial baseplate fractures following primary total knee arthroplasty (TKA). However, at a microstructural scale, it remains unclear how fatigue models developed in vitro apply to fractures in vivo. In this study, we asked: (1) do any clinical factors differentiate fracture patients from a broader revision sample; and (2) in vivo, how does microstructure influence fatigue crack propagation? We identified three fractured tibial baseplates from an institutional review board exempt implant retrieval program. Then, for comparison, we collated clinical data from the same database for n = 2120 revision TKA patients with tibial trays. To identify mechanisms, we characterized fracture features using scanning electron and digital optical microscopy. Additionally, we performed cross sectional analysis using focused ion beam milling. The fracture cohort consisted of moderately to very active patients with increased implantation time (15.6 years) compared to the larger revision patient sample (5.1 years, p = 0.009). We did not find a significant difference in patient weight between the two groups (p = 0.98). Macroscopic fracture features aligned well with both previous retrieval analysis and in vitro baseplate fatigue tests. On a micron scale, we identified striations on each baseplate, demonstrating fatigue as the fracture mechanism. In vivo fatigue fracture processes depended on both the alloy (Ti-6Al-4V vs. CoCrMo) and the microstructure of the alloy formed during manufacturing. For Ti-6Al-4V, the presence of equiaxed or acicular microstructure influenced the fatigue crack propagation, the latter arising from large prior β grains and a Widmanstatten microstructure, degrading fatigue strength. CoCrMo alloy fatigue cracks propagated linearly, crystallographically influenced by planar slip. However, we did not document any features of overload or fast fracture, suggesting a high cycle, low stress fatigue regime. Ultimately, the crack profiles we present here may provide insight into fatigue fractures of modern tibial baseplates.

Survivorship and Patient Outcomes of Conforming Bearings in Modern Primary Total Knee Arthroplasty: Mean 3.5 Year Follow-Up

BACKGROUND

The use of conforming and congruent bearings in total knee arthroplasty (TKA) have rapidly increased due to the benefits of increased stability and the potential for replicating normal knee kinematics. However, limited data exist for these newly available bearings. This study evaluated revision-free survivorship and patient-reported outcome measures (PROMs) of a large granular database of primary TKAs using a single conforming bearing design.

METHODS

A total of 1,306 consecutive primary TKAs performed using a single conforming bearing design (85% cemented and 15% cementless) were retrospectively reviewed. Kaplan-Meier survivorship estimates were calculated based on the latest clinical follow-up. The PROMs and minimal clinically important differences were evaluated. A total of 93% of cases achieved minimum 1-year clinical follow-up (mean 3.5 years; range, 1 to 7), with a subset of 261 cases that achieved minimum 5-year follow-up (mean 5.8 years; range, 5 to 7).

RESULTS

All-cause and aseptic Kaplan-Meier survivorship estimates were 97.6 (95% CI [confidence interval], 97 to 99) and 98.1% (95% CI, 97 to 99) at 7.0 years. Revision-free survivorship did not differ by cemented or cementless fixation (98 versus 97%, P = .163). All PROM scores significantly improved from preoperative baseline (P < .001), and ≥ 86% of patients achieved minimal clinically important differences for Knee Society pain and Knee Injury and Osteoarthritis Outcome Score for Joint Replacement total scores. A total of 89% of cases reported their knees to 'sometimes or always' feel normal. For cases with minimum 5-year PROMs, 93% were 'very satisfied' or 'satisfied.'

CONCLUSIONS

Conforming-bearing TKA demonstrated excellent survivorship up to 7.0 years. In addition, PROMs were comparable to other designs reported in the literature. While mid-term (mean 3.5-year) results are promising, long-term data are warranted on survivorship due to potential polyethylene wear in conforming bearings with more surface area in contact with articulating surfaces.

LEVEL OF EVIDENCE

IV.

Randomized Controlled Trial of a Novel Cementless vs. Cemented Total Knee Arthroplasty: Early Clinical and Radiographic Outcomes

OBJECTIVE

Previous cementless total knee arthroplasty (TKA) designs faced challenges with insufficient initial fixation on tibial side, resulting in inferior functional outcomes and survival rates. The Zoned Trabecular Bone Cementless Knee is a novel implant designed for cementless TKA which aims to achieve excellent initial fixation, promoting effective osseointegration. The aim of this research was to compare the early clinical and radiographic results of this cementless TKA with cemented TKA.

METHODS

Between September 2021 and April 2022, 64 patients (64 knees) were recruited in this prospective randomized controlled trial to receive either cementless 3D-printed trabecular metal TKA or a cemented posterior stabilized TKA. Preoperative and postoperative clinical evaluations, including the range of motion (ROM), Knee Society Score (KSS), and the Reduced Western Ontario and MacMaster Universities Score (WOMAC), were conducted and analyzed for comparison. Radiographs and computed tomography scans were utilized to assess the initial fixation. The complications between the two groups were also recorded and compared. Continuous data were analyzed for significance using independent-samples t-test or the Mann-Whitney U test and categorical data were analyzed using chi-squared or Fisher's exact test.

RESULTS

Both groups demonstrated significant enhancement at 12 months follow-up in the ROM compared with baseline (ROM: 94.7 ± 23.4 vs. 113.1 ± 12.3 in cementless group and 96.5 ± 14.7 vs. 111.0 ± 12.8 in cemented group, p < 0.05). However, no statistical differences were observed between the two groups in postoperative ROM, KSS, or WOMAC score. The radiographs and computed tomography scans showed similar results, including radiolucent lines and osteolysis in either femoral or tibial. Additionally, there was no statistical difference in the overall complication rate between the two groups. Notably, one patient in the cementless TKA group required revision for periprosthetic infection as the end point.

CONCLUSIONS

This novel 3D-printed trabecular metal cementless TKA achieved comparable clinical outcomes and initial fixation to cemented TKA in early stage. Longer-term examination is necessary to validate these results.

Short-Term (6 Months or Less) Pain in Cemented versus Cementless Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

Cementless total knee arthroplasty (TKA) has increased in popularity to potentially improve survivorship. Radiostereometric studies demonstrate increased component migration during the first 3 to 6 months in cementless constructs, generating concern for increased postoperative pain during early osseointegration. The purpose of this study was to evaluate short-term (≤ 6 months) pain and function in cemented versus cementless TKA. We hypothesized that cementless TKA patients report increased pain during the short-term (≤ 6 months) postoperative period.

METHODS

The MEDLINE, EMBASE, CINAHL, and Cochrane Libraries were searched for studies evaluating short-term (≤ 6 months) outcomes of cemented versus cementless primary TKA. Studies involving hybrid fixation were excluded. A meta-analysis was performed using standardized mean difference for primary outcomes (early postoperative pain) and weighted mean difference (WMD) for secondary outcomes (early postoperative function).

RESULTS

There were eleven studies included. There was no significant difference in acute postoperative pain between cemented and cementless TKA within 6 months of index TKA (standardized mean difference 0.08 in favor of cemented TKA; P = .10). Early postoperative forgotten joint scores (WMD 0.81; P = .81) and knee injury and osteoarthritis outcome scores for joint replacement (WMD 0.80 in favor of cemented TKA; P = .14) were also similar between groups.

CONCLUSIONS

There is no difference in short-term (≤ 6 months) pain or early function between patients receiving cemented and cementless TKA. This suggests that surgeons may utilize cementless TKA without fear of increased pain due to micromotion within 6 months of index arthroplasty. However, additional studies with uniform assessment methods are needed to further inform differences in short-term pain and early functional outcomes between cemented and cementless TKA.

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.

Cementless Versus Cemented Total Knee Arthroplasty: Concise Midterm Results of a Prospective Randomized Controlled Trial

BACKGROUND

We previously reported the 2-year results of a prospective randomized controlled trial of cementless versus cemented total knee arthroplasty (TKA) implants of the same design. The purpose of the present study was to provide concise results at intermediate-term follow-up.

METHODS

The original study included 141 TKAs (76 performed without cement and 65 performed with cement). Since then, 8 patients died and 4 withdrew. Of the remaining 129 patients, 127 (98%) were available for analysis. Survivorship analysis was performed; Oxford Knee, Knee Society, and Forgotten Joint Scores were calculated; and radiographs reviewed. Mean follow-up was 6 years.

RESULTS

The survivorship free of any revision was 100% in both groups. There were no differences between the groups in any patient-reported functional outcome measure (p = 0.2 to 0.5). However, a higher percentage of patients in the cementless TKA group were either extremely or very satisfied with their overall function (p = 0.01). Radiographically, there was no evidence of implant loosening in either group.

CONCLUSIONS

At 6 years, there were no differences between cementless and cemented TKA implants of the same design in terms of survivorship, clinical, or radiographic outcomes.

LEVEL OF EVIDENCE

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

Indications, clinical outcome and survival of rotating hinge total knee arthroplasty in a retrospective study of 63 primary and revision cases

PURPOSE

The purpose of this study is to report and compare outcome data of both primary and revision cases using a rotating hinge knee (RHK) implant.

METHODS

This study retrospectively analyzed 63 cases (19 primary, 44 revisions) at a mean follow-up of 34 ± 8 months after RHK implantation. Outcome parameters were stability, range of motion (ROM), loosening, Hospital of Special Surgery Score (HSS), Knee Society Score (KSS), Oxford Knee Score (OKS), EQ-5D-3L, and Visual Analog Scale (VAS) for overall function. Revision rates and implant survival are reported.

RESULTS

Eleven percent showed medio-lateral instability < 5 mm, a mean ROM of 115° ± 17° and radiologic loosening occurred in 8% (2% symptomatic). PROMS showed the following results: HSS 79 ± 18, KSS 78 ± 27, OKS 26 ± 10, EQ-5D index 0.741 ± 0.233 and VAS 70 ± 20. Primary cases revealed better outcomes in HHS (p = .035) and OKS (p = 0.047). KSS, EQ-5D index and VAS did not differ between primary and revision cases (p = 0.070; p = 0.377; p = 0.117). Revision rate was 6.3% with an implant survival of 96.8%.

CONCLUSIONS

RHK arthroplasty can be performed with good clinical outcome and low revision rate in revision and complex primary cases. RHK is an option in cases where standard arthroplasty and even implants with a higher degree of constraint have reached their limits.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Effect of Tobacco Use on Radiolucent Lines in Modern Cementless Total Knee Arthroplasty Tibial Components

Background

The link between tobacco consumption and wound complications following total knee arthroplasty (TKA) is well established. However, the effect of tobacco use on biologic fixation in cementless TKA remains unknown. This study evaluated the influence of tobacco use on the presence of radiolucent lines of tibial components in cementless TKA.

Methods

A total of 293 consecutive cementless TKAs of 2 contemporary designs were retrospectively reviewed. Tibial radiolucent lines and component alignment were measured using an established measurement protocol. Patients with any history of tobacco use or active tobacco use (tobacco users) were compared to those with no history of tobacco use (tobacco nonusers). No significant differences which influenced outcomes were detected between the tobacco user and tobacco nonuser groups (P ≥ .071).

Results

Radiolucent lines decreased from 1-month to latest follow-up (mean 2.5 years) in all 10 radiographic zones regardless of tobacco use (P ≤ .084). However, evaluating intrapatient change in radiolucent line width, the tobacco nonuser group had more radiolucent lines resolve by the latest follow-up in nearly all radiographic zones, although most differences did not reach statistical significance, except for anteroposterior zone 1 (-31% vs -19%, P = .022). No tibial components were revised for aseptic loosening.

Conclusions

Results from this study suggest that any tobacco use prior to cementless TKA has the potential to hinder biologic fixation of tibial components. While no tibial components were revised for aseptic loosening, follow-up was relatively short at 2.5 years and therefore warrants further study to discern the effect of persistent radiolucent lines on long-term fixation.

Mid-Term Performance of the First Mass-Produced Three-Dimensional Printed Cementless Tibia in the United States as Reported in the American Joint Replacement Registry

BACKGROUND

Cementless tibial components have shown improvements in clinical performance compared to predicate designs, though evidence supporting mid-term performance and fixation is scarce. The purpose of this study is to determine the mid-term survivorships, revision rates, and reasons why 3-dimensional printed cementless tibial baseplates (3DTKAs) failed compared to other cementless as well as cemented tibial baseplates reported from the American Joint Replacement Registry (AJRR) data.

METHODS

All primary total knee arthroplasty (TKA) cases performed in patients 65 years of age or older within the AJRR from January 2, 2012 through June 30, 2020 were queried. A total of 28,631 3DTKAs were identified from 428 institutions. These were compared to all other "aggregated cementless tibia" (n = 7,577) and "aggregated cemented tibia" (n = 550,133) cases. Centers for Medicare & Medicaid Services data over the same time period were merged with AJRR data to determine survivorship and patient-timed incident revision rates per 1,000 years. Failure reasons were tracked during this study period.

RESULTS

At 60 months, Kaplan-Meier implant survivorship was 98.9% (CI 98.7-99.0), 98.3% (CI 97.9-98.6), and 98.4% (CI 98.4-98.5) in the 3DTKA, aggregate cementless, and cemented knee cohorts, respectively (P < .0001). Patient-timed incident revision rates were 3.11 (CI 2.75-3.53), 3.99 (CI 3.34-4.76), and 3.35 (CI 3.28-3.42) for those cohorts, which corresponds to a revision rate of 0.31%, 0.40%, and 0.34% per year.

CONCLUSION

In this analysis, 3DTKA had favorable survivorship and lower revision rates compared to aggregate cementless and cemented TKAs implanted from the same national database during the same time period.

The influence of radiologic bone transparency after hybrid total knee arthroplasty on clinical outcomes: Minimum 6-year follow up of 214 cases

BACKGROUND

This study aimed to investigate how bone transparency affects loosening of the cementless femoral component by serially analyzing radiologic images in hybrid total knee arthroplasty (TKA).

METHODS

A total of 214 cases of TKA performed using the hybrid technique that were followed up for at least 6 years were retrospectively investigated. Bone transparency around the femoral component during the follow up period was evaluated. All TKA cases were divided into two groups and compared: those with radiologic bone transparency (bone transparency group, n = 51) and those without radiologic bone transparency (no bone transparency group, n = 163).

RESULTS

The incidence of revision TKA in all patients was 6.1%, and obesity, preoperative and postoperative mechanical alignment did not affect surgical outcomes. All bone transparency cases were asymptomatic, and only 8/51 cases (15.7%) of bone transparency spontaneously resolved. Between the bone transparency and no bone transparency groups, there was no difference found in the preoperative and postoperative radiologic parameters and clinical outcomes. During the follow up period, there were four (1.9%) cases with a definite radiolucent line in the femoral component, all of which belonged to the bone transparency group.

CONCLUSIONS

The bone transparency around the femoral component that appears on radiography after hybrid TKA could be an early sign of aseptic loosening; therefore, follow up serial radiography is essential.

Multiacquisition Variable-Resonance Image Combination Magnetic Resonance Imaging to Study Detailed Bone Apposition and Fixation of Cementless Knee System Compared to Cemented Total Knee Replacements

Background

Methods

Results

Conclusions

The mid-term survival of cemented, uncemented, and hybrid fixation of the ACS mobile bearing total knee arthroplasty

Background

Till today, Cemented Fixation in Total Knee Arthroplasty (TKA) is significantly more used than Hybrid or Uncemented Fixation. The purpose of this study was to compare Cemented, Uncemented and Hybrid Fixation of the ACS Mobile Bearing TKA at Mid-term follow-up.

Methods

This study was an extended data report of our prospective single-center, single-blinded randomized controlled clinical trial comprising 105 patients. The primary outcome was survival at five years of follow-up calculated by Kaplan-Meier and Log-rank test. The secondary outcome was function based on patient-reported outcome measures (PROMs).

Results

Eighty-three patients were included, of which 25 belonged into group A (Cemented), 28 in group B (Uncemented), and 30 in group C (Hybrid). Mean follow-up was 5.8 ± 0.7 (range 5-7) years. The 5-year survival rates were 96.8% (95%CI: 90.5; 100) in the Cemented group, 94.2% (95%CI: 86.4; 100) in the Uncemented group, and 93.8% (95%CI: 85.4; 100) in the Hybrid group for revision for any reason (p = 0.80). Functional outcome was similar among the groups.

Conclusion

In our cohort of ACS Mobile Bearing TKA, there was no difference between Cemented, Uncemented, and Hybrid Fixation with regard to survival and function at Mid-term follow-up.

Trial registration

Dutch Trial Register (NTR3893), 2013-03-12.

Level of evidence

II.

Short- to Mid-Term Clinical Outcomes of Posterior-Stabilized Cementless Total Knee Arthroplasty with Trabecular Metal Components

Objective

This study aimed to evaluate the short- to mid-term clinical results of posterior-stabilized trabecular metal total knee arthroplasty (TKA) with cementless fixation of all components and investigate the radiographic changes of tibial and patellar components and cut bone surfaces over time.

Methods

We retrospectively collected the data of 128 knees from 88 consecutive patients who had undergone initial TKA with NexGen LPS-Flex TM implants. A total of 66 knees from 45 patients (mean ± standard deviation age: 70.3 ± 7.5 years) met the selection criteria, which had been employed cementless fixation of all parts and at least 3 years of postoperative follow-up duration. Clinical evaluations included range of motion, conventional knee score, function score, postoperative complications, and revision. For radiological evaluations, the bone contact surface of each implant was divided into 7 zones for tibial component and 2 zones for patellar component. Each region was examined immediately after surgery, at 6 and 12 months, and then every year afterwards.

Results

The mean observation period of 45 subjects was 4.2 years. Adequate fixation of tibial components was maintained during follow-up, although the patellar components of 2 knees required revision after repeated falls. No loosening was observed in any implants. The initial gap in tibial components disappeared in all knees, and a reactive line remained in 4 knees. There were no revisions, except for 2 cases, which were ascribed to patellar component fracture caused by repeated falls.

Conclusion

Cementless posterior-stabilized trabecular metal TKA appears to be a good surgical option. Longer-term examination for revision cases is required to validate our results.