Interleukin-6 serum concentration in the elderly undergoing total knee arthroplasty: A potential predictor of the early postoperative knee joint range of motion

Abstract

PURPOSE:

To analyze the relevance between serum IL-6 with the early postoperative (post-op) knee joint range of motion (ROM) in the elderly undergoing total knee arthroplasty (TKA). To evaluate the factors affecting early post-op knee joint ROM in the elderly after TKA.

METHODS:

One hundred and forty-three patients undergoing TKA were included. The patients’ general data, perioperative knee joint ROM and serum IL-6, pre-op HSS, WOMAC, SF-36 scores and Wells scores were collected. Repeated data variance analyses were performed to analyze the relevance between serum IL-6 with post-op knee joint ROM. Correlative regression and regression analysis were performed to evaluate the multiple factors affecting knee joint ROM in the elderly undergoing TKA.

RESULTS:

The 2-week-post-op (2w-post-op) knee joint ROM was significantly higher in the low IL-6 serum concentration group ( $<$ 46.45 ng/L) than in the high group ( $⩾$ 46.45 ng/L) (97.78 $\pm$ 7.44 ${}^{\circ }$ VS 91.85 $\pm$ 7.42 ${}^{\circ }$ , $F=$ 16.860, $P=$ 0.000). A significant negative correlation was found between 1d-post-op serum IL-6 concentration with 2w-post-op knee joint ROM ( $R=$ $-$ 0.513, $P=$ 0.000). The factors influencing the 2w-post-op knee joint ROM included pre-op HSS scores, pre-op WOMAC scores and whether to retain PCL (posterior cruciate ligament) ( $R^2=$ 0.451, $P=$ 0.009).

CONCLUSION:

A higher 1d-post-op IL-6 serum concentration indicated a lower knee joint ROM in the elderly two weeks after TKA.