Early migration of tibial components is associated with late revision: a systematic review and meta-analysis of 21,000 knee arthroplasties

Abstract

Purpose: We performed two parallel systematic reviews and meta-analyses to determine the association between early migration of tibial components and late aseptic revision.

Methods: One review comprised early migration data from radiostereometric analysis (RSA) studies, while the other focused on revision rates for aseptic loosening from long-term survival studies. Thresholds for acceptable and unacceptable migration were determined according to that of several national joint registries: < 5% revision at 10 years.

Results: Following an elaborate literature search, 50 studies (involving 847 total knee prostheses (TKPs)) were included in the RSA review and 56 studies (20,599 TKPs) were included in the survival review. The results showed that for every mm increase in migration there was an 8% increase in revision rate, which remained after correction for age, sex, diagnosis, hospital type, continent, and study quality. Consequently, migration up to 0.5 mm was considered acceptable during the first postoperative year, while migration of 1.6 mm or more was unacceptable. TKPs with migration of between 0.5 and 1.6 mm were considered to be at risk of having revision rates higher than 5% at 10 years.

Interpretation: There was a clinically relevant association between early migration of TKPs and late revision for loosening. The proposed migration thresholds can be implemented in a phased, evidence-based introduction of new types of knee prostheses, since they allow early detection of high-risk TKPs while exposing only a small number of patients.

Figure 1.

PRISMA flow chart of both reviews. Details of the 28 PFI combinations are given in Table 1. RSA: radiostereometric analysis; TKP: total knee prosthesis; FU: follow-up; PFI: prosthesis-fixation-insert combination.

Figure 2.

Scatter plot showing association between migration in the first postoperative year expressed as maximal total point motion (MTPM) in mm and revision rate for aseptic loosening of the tibial component at 5 years, as a percentage. The colored lines are derived from weighted regression according to match quality, survival study quality, and RSA study quality (the coefficients and 95% CI are given in Table 2).

Figure 3.

Scatter plot showing the relation between MTPM at 1 year and revision of the tibial component for aseptic loosening at 5 years. The thresholds of 0.54 mm and 1.6 mm for the three categories (acceptable, at risk, and unacceptable) are shown.

Figure 4.

Scatter plot showing the relation between MTPM at 1 year and revision of the tibial component for aseptic loosening at 10 years. The thresholds of 0.45 mm and 1.6 mm for the three categories (acceptable, at risk, and unacceptable) are shown.

Figure 5.

Dot chart showing the pooled MTPM ranked by the pooled revision rate for each PFI combination. The acceptable PFI combinations (based on migration) had excellent track records and low revision rates in several national registries, whereas the unacceptable PFI combinations (based on migration) have been abandoned. Thus, the potential influence of publication bias on the results is small. A detailed description of each PFI combination is given in Table 1. R5(%): pooled revision rate at 5-year follow-up, as a percentage.

Figure 6.

Flow chart showing the role of RSA studies in the phased evidence-based introduction of new TKPs, modified according the Malchau proposal. Stabilization is defined as migration of less than 0.2 mm in the second postoperative year (MTPM from year 1 to year 2) as described by Ryd et al. (1995). See discussion for details of each phase.