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.

RSA migration of total knee replacements.

Purpose - We performed a systematic review and meta-analyses to evaluate the early and long-term migration patterns of tibial components of TKR of all known RSA studies. Methods - Migration pattern was defined as at least 2 postoperative RSA follow-up moments. Maximal total point motion (MTPM) at 6 weeks, 3 months, 6 months, 1 year, 2 years, 5 years, and 10 years were considered. Results - The literature search yielded 1,167 hits of which 53 studies were included, comprising 111 study groups and 2,470 knees. The majority of the early migration occurred in the first 6 months postoperatively followed by a period of stability, i.e., no or very little migration. Cemented and uncemented tibial components had different migration patterns. For cemented tibial components there was no difference in migration between all-poly and metal-backed components, between mobile bearing and fixed bearing, between cruciate retaining and posterior stabilized. Furthermore, no difference existed between TKR measured with model-based RSA or marker-based RSA methods. For uncemented TKR there was some variation in migration with the highest migration for uncoated TKR. Interpretation - The results from this meta-analysis on RSA migration of TKR are in line with both the survival analyses results from joint registries of these TKRs as well as revision rates results from meta-analyses, thus providing further proof for the association between early migration and late revision for loosening. The pooled migration patterns can be used both as benchmarks and for defining migration thresholds for future evaluation of new TKR.

Return to work after total hip and knee arthroplasty: a systematic review.

OBJECTIVES: The aim of this study was to describe work status and time to return to work in patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA) and to determine which factors are associated with work status. METHODS: A systematic search strategy in various databases through April 2013 was performed. All clinical studies concerning patients undergoing THA or TKA providing quantitative information on work status before and after surgery were eligible for inclusion. Extracted were study characteristics, data on work status and determinants of return to work. The methodological quality was evaluated in three quality aspects (selection bias, information bias and statistical analysis bias). RESULTS: Nineteen studies published between 1986 and 2013 were selected (4 on THA, 14 on TKA and 1 on THA and TKA). These studies included 3872 patients with THA and 649 patients with TKA. The proportions of patients returning to work ranged from 25 to 95% at 1-12 months after THA and from 71 to 83% at 3-6 months after TKA. The average time to return to work varied from 1.1 to 13.9 weeks after THA and from 8.0 to 12.0 weeks after TKA. Factors related to work status after THA and TKA included sociodemographic, health and job characteristics. Overall, the methodological quality of the studies was moderate to low. CONCLUSION: The majority of patients who are employed before THA and TKA return to work postoperatively. Comparisons of work status and the rate and speed of return to work between studies in THA and TKA are hampered by large variations in patient selection and measurement methods, underpinning the need for more standardization.