Summary

The theoretical advantages of this study are that the use of short extension tibial stems in primary knee arthroplasty mitigates the risk of mechanical complications in morbidly obese patients, and that no complications are reported with their use.

Abstract

Introduction

The use of tibial stems in total knee arthroplasty (TKA) has emerged as an alternative for patients with morbid obesity (MO) in order to reduce bone collapse and aseptic tibial loosening. The aim of this study was to compare pain, functional capacity, and postoperative complications in morbidly obese patients undergoing TKA without a tibial stem vs. with a tibial stem.

Methods

Clinical, non-blind, randomized, retrospective, longitudinal study of patients with MO (BMI>40kg/m2) who underwent TKA (n=112) between July 2015 and July 2017. Group A (n=63) with a conventional prosthesis and group B (n=49) a prosthesis with a tibial stem, with a 5-year follow-up. For statistical analysis, the Kruskal-Wallis test (continuous variables) and chi-square (categorical variables) were used.

Results

Statistically significant differences (p=.000) were found in pain with the VAS scale (Group A 0.57±0.89 vs. Group B 0.55±0.56), WOMAC questionnaire (Group A 6.02±3.97 vs. Group B 4.12±3.12) and form IKDC 2000 (Group A 71.19±13.51 vs Group B 82.74±7.89) at 36 months. With regard to postoperative complications, they were found in 21.4% of the sample, with aseptic tibial loosening and surgical wound closure being the most common. All mechanical complications occurred in the group without a tibial stem.

Conclusions

In conclusion, the results of this study suggest that the use of tibial stems in TKA reduces the risk of aseptic tibial loosening in morbidly obese patients at early follow-up.