Long-Term Assessment of Highly Cross-Linked and Compression-Molded Polyethylene Inserts for Posterior Cruciate-Substituting TKA in Young Patients: A Concise Follow-up of a Previous Report

Comparison of Functional Recovery Between Unicompartmental and Total Knee Arthroplasty: A Randomized Controlled Trial

BACKGROUND

Comparisons of functional recovery between unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) using performance-based tests are lacking. Therefore, this study aimed to compare 2-minute walk test (2MWT) and Timed Up-and-Go test (TUG) results between UKA and TKA for isolated medial knee osteoarthritis (OA). We hypothesized that UKA yields faster functional recovery than TKA as measured with the 2MWT and TUG.

METHODS

We conducted a randomized controlled trial comparing medial UKA and TKA in patients with isolated medial knee OA. A total of 110 patients were enrolled; after 11 exclusions, 99 patients (50 UKA, 49 TKA) were included in the final analysis. The patients were tested using the 2MWT and TUG preoperatively and at 6 weeks, 3 and 6 months, and 1 and 2 years postoperatively. Patient-reported outcome measures (PROMs) were also evaluated. The mean 2MWT, TUG, and PROM results were compared between groups at each time point.

RESULTS

The mean 2MWT distance after UKA was significantly longer than that after TKA at 6 weeks (96.5 ± 22.6 m for UKA compared with 81.1 ± 19.1 m for TKA; difference, 18 m [95% confidence interval (CI),10.4 to 25.6 m]; p < 0.001), 3 months (102.1± 24.4 compared with 87.5 ± 22.3 m; difference, 14.7 m [95% CI, 5.4 to 24.0 m]; p = 0.002), and 6 months (102.8 ± 16.2 compared with 89.6 ± 15.3 m; difference, 13.2 m [95% CI, 6.9 to 19.5 m]; p < 0.001). The values at 1 and 2 years were similar after UKA and TKA. The mean TUG after UKA was also significantly shorter than that after TKA at 6 weeks and 3 months. The mean PROMs were similar after both treatments, with the exception of the Oxford Knee Score and subscales of the Knee injury and Osteoarthritis Outcome Score at 6 weeks and 3 months postoperatively.

CONCLUSIONS

The 2MWT indicated that UKA for isolated medial knee OA enabled faster recovery than TKA did at 6 weeks to 6 months, and earlier recovery was also seen with the TUG at 6 weeks to 3 months. The 2MWT and TUG results after UKA and TKA were similar to one another at 1 and 2 years.

LEVEL OF EVIDENCE

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

Highly cross-linked polyethylene in primary total knee arthroplasty is associated with a lower rate of revision for aseptic loosening: a meta-analysis of 962,467 cases

BACKGROUND

The evolution in total knee arthroplasty (TKA) includes the highly cross-linked polyethylene (HXLPE) which has been reported as an effective manner to reduce the wear of the polyethylene and the osteolysis. The purpose of the present study is to synthesize the results of comparative studies between HXLPE and conventional polyethylenes and determine their effect in primary TKA.

METHODS

The US National Library of Medicine (PubMed/MEDLINE) and the Cochrane Database of Systematic Reviews were queried for publications utilizing the following keywords: "cross-linked", "polyethylene", "HXLPE", "conventional", "total knee arthroplasty", "TKA", "total knee replacement" and "TKR" combined with Boolean operators AND and OR.

RESULTS

Ten studies met the inclusion criteria and were included in the present meta-analysis with 962,467 patients. No significant difference was found regarding the revision rate for any reason between the patients who received HXLPE and those with conventional liner (OR 0.67; 95% CI 0.39-1.18; I²: 97.7%). In addition, there was no difference regarding the radiolucent lines between the two types of liners (OR 0.54; 95% CI 0.20-1.49; I²: 69.4%). However, with data coming from seven studies enrolling a total of 411,543 patients, it was demonstrated that patients who received HXLPE were less likely to be revised due to aseptic loosening compared to the patients with conventional liners (OR 0.35; 95% CI 0.31-0.39; I²: 0.0%).

CONCLUSION

The present meta-analysis showed that regarding the overall revision rate and radiographic outcomes there was no significant difference between the two types of liners. On the other hand, the significantly less revision rate due to loosening supports the routine continued use of HXLPE in primary TKA.

Comparable results between crosslinked polyethylene and conventional ultra-high molecular weight polyethylene implanted in total knee arthroplasty: systematic review and meta-analysis of randomised clinical trials

PURPOSE

Total knee arthroplasty (TKA) has experienced exponential growth over the last decade, including increasingly younger patients with high functional demands. Highly crosslinked polyethylene (HXLPE) has been proven effective in reducing osteolysis and loosening revisions while improving long-term survival and performance in total hip arthroplasty; nevertheless, this superiority is not demonstrated in TKA. The aim of this systematic review and meta-analysis was to examine whether HXLPE improved overall survival and postoperative functional and radiological outcomes compared to conventional polyethylene (CPE) in TKA.

METHODS

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline, a literature search of five databases (PubMed, Medline, Scopus, Science Direct and Embase) was made. A PICOS model was performed. The initial screening identified 2541 studies. Each eligible clinical article was analysed according to the Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence (LoE). Only randomised clinical trials (RCTs) of LoE 1 and 2 were included. The methodological quality of the articles was assessed using the Risk of Bias 2 (RoB 2) tool.

RESULTS

Six clinical studies were included in the final study. This systematic review and meta-analysis were registered on the International Prospective Register of Systematic Reviews (PROSPERO). A total of 2285 knees were included. Eight outcomes (total reoperations, reoperations for prosthesis loosening and infections, radiolucent lines, osteolysis, mechanical failure, postoperative KSS knee score and function score) were analysed. For none of them, a statistically significant difference was found about the superiority of HXLPE over CPE (p > 0.05).

CONCLUSIONS

There were no statistically significant differences between HXLPE and CPE for TKA concerning clinical, radiological, and functional outcomes; nevertheless, HXLPE did not show higher failure rates or complications and can be safely used for TKA.

LEVEL OF EVIDENCE

II.