Influence of Preoperative Deformity on Flexion Gap Asymmetry in Measured Resection Technique: A Theoretical Study in Navigated Gap Balancing Total Knee Arthroplasties, Done for Varus Knee Osteoarthritis.

INTRODUCTION: Disagreement exists on (a) achieving a symmetrical flexion gap and (b) the influence of varus deformity on the flexion gap asymmetry (FGA) in measured resection (MR) total knee arthroplasty (TKA). We aimed to determine the FGA and influence of preoperative deformity on the FGA, based on the MR technique, in varus knee osteoarthritis. METHODS: In 321 navigated TKAs, we released the soft tissues in extension. In 90° flexion, with the tensioner in situ, we calculated the FGA, the angle between the posterior femoral cut (planned 3° external rotation to the posterior condylar line, parallel to the surgical transepicondylar axis, or perpendicular to the Whiteside line) and the proximal tibial resection plane. RESULTS: The FGA values varied widely, and the risk of >2° and >3° FGA was present in at least 60% and 40% knees, respectively. These risks were high in knees with moderate and severe varus deformity. CONCLUSIONS: In varus knee osteoarthritis, the risk of FGA (based on the MR technique) was high, especially when the deformity was moderate to severe. Caution is required in MR TKA, and surgeons must consider safer alternatives (gap balancing or hybrid technique) to achieve a symmetrical flexion gap in these knees.

Cruciate retaining total knee arthroplasty has a better 10 year survival than posterior stabilized total knee arthroplasty: a systematic review and meta-analysis.

PURPOSE: There has been a long standing debate regarding superiority of cruciate retaining total knee arthroplasty over posterior stabilized total knee arthroplasty regarding the short-term outcomes as well as long-term survivorship. The proponents of both the techniques have published vast evidence in favor of their respective surgical method and early outcome in meta-analyses does not seem to be significantly different. The decision to select either design should depend on their long-term survivorship but the literature comparing their long-term survival is sparse.This meta-analysis was conducted in order to answer the following questions: (1) Does cruciate retaining total knee arthroplasty has a better long-term survival beyond 10 years.compared to posterior stabilized total knee arthroplasty? (2) Does cruciate retaining knee arthroplasty has higher complication rates compared to posterior stabilized total knee arthroplasty? METHODS: The present systematic review and meta-analysis study was carried out following PRISMA guidelines. The following databases: Embase, Web of Science, PubMed, Scopus, the Cochrane Library, Google Scholar, and CINAHL were used to search potentially interesting articles published from database inception until January 2022. Inclusion criteria for articles were: (1) retrospective comparative studies; (2) patients who had undergone a total knee arthroplasty; (3) publications evaluating the long-term survival of cruciate-retaining (CR) versus posterior stabilizing (PS) at a minimum 10 years' follow-up; (4) publications evaluating complications of cruciate-retaining (CR) versus posterior stabilizing (PS) at a minimum 10 years' follow-up; and (5) publications reporting sufficient data regarding the outcomes. We used a fixed-effects design in the case of I2 < 50% and P > 0.05; if not, we adopted a random-effects design [4]. We also performed subgroups and sensitivity analysis in order to assess the possible source of heterogeneity. RESULTS: Database searching identified 597 studies to be screened, of which 291 abstracts were revealed as potentially eligible and finally 7 articles were included. The forest plot showed that CR had significantly better survival than PS (OR = 2.17; 95% CI: 1.69-2.80) after 10 years. However, complication rate was not significantly different between CR and PS groups (OR = 0.86; 95% CI: 0.52-1.44; P = 0.57). Subgroup analysis showed that only the period of publication constituted a source of heterogeneity in survivorship outcome. Sensitivity analysis revealed that outcomes did not differ markedly, which indicates that the meta-analysis had strong reliability. CONCLUSION: The results of this meta-analysis showed that cruciate retaining prosthesis may be preferred over the posterior stabilized design in view of longer survivorship it offers However, further randomized controlled trials are recommended to confirm this finding.