Two-year fixation and ten-year clinical outcomes of total knee arthroplasty inserted with normal-curing bone cement and slow-curing bone cement: A randomized controlled trial in 54 patients

Precision of computer tomography based RSA on femoral implants in total knee arthroplasty: A porcine cadaver study

BACKGROUND

Radiostereometric analysis is the gold standard for assessing migration of orthopaedic implants. The novel CT-based radiostereometric analysis yields high precision of evaluation of tibial implants. We analyzed the precision of CT-based radiostereometric analysis on femoral implants in knee arthroplasty at different dose levels, and compared it to previously published results on tibial implants and the available literature on precision of radiostereometric analysis.

METHODS

We performed a total knee arthroplasty on a porcine cadaver knee. In the subsequent 7 CT scans, we analyzed the precision of the CT-based radiostereometric analysis method in 21 samples at two different effective doses (standard and low dose), and compared this to literature on radiostereometric analysis.

FINDINGS

CT-based radiostereometric analysis of maximum total point motion of femoral and tibial components showed a precision difference of (mean, 95 % confidence interval) 0.18 mm (0.13 to 0.22), P < 0.001. For femoral implants (mean, 95 % confidence interval, standard deviation) we found precisions of 0.25 mm (0.21-0.29, 0.1) and 0.29 (0.25-0.32, 0.08) mm for the standard and low dose protocols respectively. Variability ratios of tibia versus femur and standard versus low dose femur (95 % confidence interval) were 18.3 (7.4-45.1) and 0.7 (0.3-1.7) with respective P-values of <0.001 and 0.40.

INTERPRETATION

CT-based radiostereometric analysis on femoral implants in total knee arthroplasty is feasible and has a lower, yet still acceptable, precision compared to CT-based radiostereometric analysis on tibial implants in a porcine cadaver. However, confirmation in clinical studies is warranted.

Factors influencing periprosthetic bone mineral density in total knee arthroplasty: a systematic review

INTRODUCTION

Following total knee arthroplasty (TKA), there is a significant decline in periprosthetic bone mineral density (BMD), potentially resulting in complications such as prosthetic loosening, periprosthetic fracture, and influencing the postoperative recovery. The objective of this study was to summarize the factors influencing periprosthetic BMD in TKA from existing studies.

METHODS

A comprehensive systematic search was performed in 4 databases: Pubmed, Embase, Web of Science, and Cochrane Library. The last search was carried out on October 12, 2023. We used the keywords ''total knee arthroplasty'', ''bone mineral density'' and each of them combined with ''tibia'' and ''femur'' to identify all relevant articles reporting about potential impact factors influencing the periprosthetic BMD in patients after TKA.

RESULTS

Out of 1391 articles, 22 published from 2001 to 2023 were included in this systematic review. Following eligibility screening, six significant categories affecting periprosthetic BMD were recognized: prosthesis type, design of stem, coating, body weight, cement, and peg distance.

CONCLUSION

Mobile-bearing prostheses, modular polyethylene design, short stems, cruciform stems, avoidance of bone cement, higher body mass index, titanium nitride coating, and a smaller medial peg distance could potentially benefit periprosthetic BMD. Comprehensive consideration of diverse factors influencing periprosthetic BMD before surgery and collaboration with post-operative drug therapy are essential.

TRIAL REGISTRY

The PROSPERO registration number is CRD42023472030.

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.