To investigate the preventive and alleviating effects of preoperative regular exercise on periprosthetic knee joint infection in mice.

A knee periprosthetic joint infection (PJI) model was established in C57BL/6 male mice. The mice were divided into three groups: a blank control group, a PJI group, and a preoperative regular exercise + PJI group. The preoperative regular exercise + PJI group underwent a 6-week regular treadmill exercise intervention before the PJI model was established. Four weeks postoperatively, the infectious burden of PJI, osteolysis, inflammatory response, and the tissue repair microenvironment were assessed through gross observation, X-ray imaging, Micro-CT analysis, Giemsa staining, histopathological staining (H&E, TRAP, Alcian blue, COL1A1 immunofluorescence), and qPCR detection.

Compared to the PJI group, preoperative regular exercise significantly reduced the severity of PJI and bacterial load, alleviated osteolysis (as evidenced by reduced periosteal reaction, decreased osteoclast numbers, and improved bone microarchitectural parameters such as BMD and BV/TV), decreased the expression levels of pro-inflammatory factors (Il1b, Il6, Tnf, Cxcl15, Myd88, Tlr4), while concurrently upregulating the expression of anti-inflammatory factors (Il4, Il10), and diminished local tissue inflammatory infiltration and the degree of fibrosis.

Preoperative regular exercise can effectively alleviate the severity of periprosthetic joint infection (PJI) in mice by reducing infectious burden, mitigating osteolysis, controlling the inflammatory response, and improving the tissue repair microenvironment. This provides new experimental evidence and potential strategies for the clinical prevention of PJI.