Modern cementless posterior stabilized mobile-bearing total knee arthroplasty shows comparable clinical and radiographical results to its cemented predecessor at 1-year follow-up

The vast majority of radiolucent lines disappeared at 3 years follow-up in modern cementless posterior stabilized mobile-bearing total knee arthroplasty

PURPOSE

The purpose of this study was to evaluate the natural history of radiolucent lines (RLLs) in modern cementless posterior-stabilized (PS) mobile-bearing total knee arthroplasty (TKA) at 3-year follow-up.

METHODS

Our cohort was composed of 45 cementless and 45 cemented TKAs. Patients were retrospectively reviewed after 1:1 matching for age, gender, body mass index, and preoperative UCLA score. All operative procedures were performed by a single surgeon using a cementless or cemented TKA of the same design between 2019 and 2021. The incidence of RLLs was reviewed at 1 week, 6 months, 1 year, 2 years, and 3 years postoperatively. Bone on-growth over the surface of the implants were also reviewed at 3 years postoperatively. Fisher's exact test, independent Student's t-test, or Mann-Whitney U test were used for statistical analyses.

RESULTS

Although the incidence of RLLs was significantly higher in cementless TKAs (33/45 knees; 73%) than that in cemented TKAs (10/45 knees; 22%, P <.01) at 6 months postoperatively, RLLs in cementless TKAs disappeared in 29 of 33 knees (88%) at 3-year postoperatively and those of cemented TKAs had increased up to 17 of 45 knees (38%). Bone on-growth over the surface of the implants was observed in 43 of 45 knees (93%) in the cementless TKAs at 3 years postoperatively.

CONCLUSION

This study showed that nonprogressive RLLs in recently introduced cementless PS mobile-bearing TKA designs are expected to disappear over time.

LEVEL OF EVIDENCE

Retrospective cohort study, Level III.

Early radiographic evaluation of an anatomic porous tantalum tibia: A prospective, multi-center, non-randomized clinical study

BACKGROUND

Excellent survival rates have been reported for total knee arthroplasty (TKA) performed with cementless porous metal tibial components. More data, however, is necessary to assess the survival and radiographic results of modular implants with anatomic designs. The purpose of this study was to investigate the early radiographic, survival, and clinical outcomes of a cementless tantalum metal tibial implant with a modular anatomic component.

METHODS

An early follow-up of a prospective, multi-center, non-randomized outcomes study of patients who received cementless tibial implants in primary TKA between 2018 and 2020 was performed. A total of 148 implants were available for review. Radiographs, the Forgotten Joint Score (FJS-12), Oxford Knee Score (OKS), patient satisfaction, and adverse events were collected for at least two-years post-operative. A minimum of two-years follow-up was available for 119 patients and evaluated for progressive radiolucent lines (RLLs).

RESULTS

The mean follow-up was 2.2 ± 0.6 years, and the two-year implant survival rate was 98.59% (95% C.I.: 94.46, 99.64) with no aseptic revisions during the follow-up period. Progressive tibial RLLs were present in 3.4% of patients at two-years follow-up, but were all less than 2 mm with all combined RLLs less than 4 mm. The FJS-12 and OKS all significantly (p < 0.0001) increased and exceeded their respective minimal clinical important differences, and 93% of patients were satisfied at two-years follow-up.

CONCLUSION

This study supports excellent survivorship, clinical and patient reported outcomes using cementless, fixed bearing TKA with minimal complications at early follow-up. Further follow-up is necessary to confirm the sustainability of the clinical outcomes and to evaluate mid- to long-term survivorship.

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.

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.

Survivorship and complications of cementless compared to cemented posterior-stabilized total knee arthroplasties: A systematic review and meta-analysis

PURPOSE

Controversy exists on the best fixation for total knee arthroplasty (TKA). Non-cemented fixation has been theorized to improve patient outcomes and longevity of implantation but no study has focused on comparison between cemented or cementless posterior-stabilized implants despite being the most commonly or second most frequently utilized implant in most total knee replacement registries.

METHODS

Inclusion criteria with observational and interventional papers, and review articles that focused on patients with cementless and cemented PS TKAs were used to analyze outcomes such as implant survivorship, complication, or revision rates. Using a combination of keywords, a systematic search was performed on Medline (PubMed), Embase, and Cochrane Library for Meta-Analysis.

RESULTS

When using the specified criteria, only 8 studies were selected for full-text analysis and meta-analysis after eliminating screening duplicates, titles, and abstracts without full-text access. These eight studies contain 1652 patients, 693 in the non-cemented Group, and 959 in the cemented total knee prosthesis Group. The meta-analysis revealed the advantage of cementless fixation over cemented fixation in implant survivorship, with 0.6% and 2.6% of aseptic loosening in each Group. The cumulative survival at 12 years was 97.4% for the cementless Group and 89.2% for the cemented Group. The subgroup with a stem showed a positive outcome for cementless fixation over cemented fixation regarding implant survivorship. No differences between the cemented and cementless TKAs were observed in patient-reported outcomes, revision rates, or radiolucent line development.

CONCLUSION

We observed comparable rates for cemented and cementless posterior-stabilized TKAs over a medium-term follow-up 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.