The dynamics of perioperative serum albumin before and after total knee arthroplasty

Background: Previous studies have evaluated preoperative serum albumin (SA) for predicting postoperative complications of total knee arthroplasty (TKA). This study aimed to investigate the dynamics of perioperative SA and changes in SA (ΔSA) and identify any influential patient or surgical factors.

Methods: In total, 381 patients (483 knees) undergoing primary TKA were recruited. SA values preoperatively (SA₀), 1 week postoperatively (SA_1W), and 4 weeks postoperatively (SA_4W) were investigated. SA values were converted to a percentage of SA₀ and differences between timepoints were calculated and expressed as follows: ΔSA_1W-0, ΔSA_4W-_1W, and ΔSA_4W-0. Patient and surgical factors previously identified or with the potential to influence SA were evaluated.

Results: The median values of SA₀, SA_1W, and SA_4W were 4.4, 3.8, and 4.2 g/dL, respectively; SA₀ was significantly different between groups (p < 0.001). The incidence of low SA₀ (<3.5 g/dL) was less than 1 %. Median ΔSA values were -13.7 %, 9.6 %, and -4.5 % for ΔSA_1W-0, ΔSA_4W-_1W and ΔSA_4W-0, respectively; ΔSA was significantly different between groups (p < 0.001). SA_4W recovered to 95.5 % of SA₀ with less than 2 % of patients having low SA_4W (<3.5 g/dL). Multiple regression analyses showed SA concentration at each timepoint was significantly associated with the other SA timepoint values; age was significantly associated with SA_4W and SA_1W (all p < 0.001).

Conclusions: We identified SA₀ and age as significant factors affecting SA dynamics in the perioperative period. Low SA (<3.5 g/dL) was uncommon both preoperatively and at 4 weeks postoperatively; therefore, conventional cutoff values and preventive measures for low SA may need reconsideration.