Length of stay and short-term functional outcomes after total knee arthroplasty : can we predict them?

Background: To identify variables influencing length of stay (LOS) and short-term functional outcome in patients undergoing total knee arthroplasty (TKA). A secondary aim was to verify the effect of the same variables on blood management and the rate of postoperative infection. Method: We retrospectively reviewed 353 patients, 258 females and 85 males, who underwent primary MA in a single specialist orthopaedic centre. Anamnestic and anthropometric data and the Modified Barthel Index Score (MBI) at admission were recorded, and entered as covariates in four longitudinal regression models, separately carried out for female and male groups. The regression outcomes were LOS, MBI change, rate of infection and blood transfusion. Statistical significance was set at p < 0.05. Results: Mean LOS was 15.93 +/- 4.97 days for females and 13.41 +/- 3.63 days for males. Mean MBI improvement was statistically significant in both groups. 46.3% females and 29.4% males needed at least one blood transfusion, while infections complicated the hospitalization in 14.6% and 4.7% cases respectively. Among females, older age was predictive for a longer LOS and poorer post-operative MBI improvement. Lower MBI at admission was related to a longer LOS and to a higher risk of post-surgical infections in the female group, but to a better improvement of functional outcome in both groups. A higher rate of blood transfusion postoperatively was associated to lower pre-surgical haemoglobin levels and, for females, to older age and lower BMI. Conclusion: An accurate characterization of TKA candidates might help in reducing LOS and in achieving a better early functional outcome.