Abstract: Objective  To analyze the relationship between plasma mitochondrial DNA(mtDNA),macrophage inflammatory protein-1α(MIP1α) and monocyte chemotactic protein 1(MCP-1) in vastus lateralis tissues and postoperative muscle atrophy,recovery of hip function in patients with hip fractures.Methods A total of 86 patients with hip fractures and 43 patients with coxitis in Jinan Eighth People’s Hospital were enrolled as hip fracture group and coxitis group between October 2020 and October 2022,respectively.The lateral muscle tissues were collected as samples during surgery.The level of plasma mtDNA was detected by real-time fluorescence quantitative polymerase chain reaction.Before surgery,levels of serum interleukin-6(IL-6) and tumor necrosis factor α(TNF-α) were detected by enzyme-linked immunosorbent assay.Before surgery,cross-sectional areas of types I and II vastus lateralis fibers were detected by immunofluorescence method.Before surgery,expression levels of MIP1α and MCP-1 proteins in lateral muscle tissues were detected by Western blot.All patients with hip fracture were effectively followed up for 6 months after surgery.At 3 and 6 months after surgery,total lean mass(TLM) and unaffected limb lean mass(ULLM) were detected by DXA.Results  The level of plasma mtDNA in hip fracture group was higher than that in coxitis group before surgery [(4.12±0.53) vs(2.37±0.36),P<0.05],levels of serum IL-6 and TNF-α were higher than those in coxitis group [(34.68±6.14)pg/ml,(21.54±4.12)pg/ml vs(12.74±3.06)pg/ml,(10.81±2.71)pg/ml,P<0.05],cross-sectional areas of types I and II vastus lateralis fibers were smaller than those in coxitis group [(4321.45±441.36) μm²,(2384.38±247.11) μm² vs(5417.63±553.27) μm²,(3569.24±368.22) μm²,P<0.05],and expression levels of MIP1α and MCP-1 proteins were higher than those in coxitis group [(2.34±0.25),(2.47±0.28) vs(1.18±0.15),(1.95±0.23),P<0.05].In patients with hip fracture after 6 months of follow-up,there were 53 cases with good prognosis and 33 cases with poor prognosis.The level of plasma mtDNA in poor prognosis group was higher than that in good prognosis group before surgery [(4.53±0.52) vs(3.87±0.44),P<0.05],levels of serum IL-6 and TNF-α were higher than those in good prognosis group [(35.97±5.32)pg/ml,(20.74±4.27)pg/ml vs(33.51±5.16)pg/ml,(22.83±4.33)pg/ml,P<0.05],cross-sectional areas of types I and II vastus lateralis fibers were smaller than those in good prognosis group [(4174.26±434.60) μm²,(2309.56±246.18) μm² vs(4394.42±450.12) μm-2,(2430.97±250.72) μm-2,P<0.05],and expression levels of MIP1α and MCP-1 proteins were higher than those in good prognosis group [(2.47±0.28),(1.95±0.23) vs(2.26±0.24),(1.82±0.21),P<0.05].TLM and ULLM at 6 months after surgery were lower than those at 3 months after surgery in good prognosis group and poor prognosis group(P<0.05).At 3 and 6 months after surgery,there was no significant different in TLM or ULLM between good prognosis group and poor prognosis group(P>0.05).Conclusion  Traumatic stress injury will increase level of plasma mtDNA in patients with hip fracture,which will induce the increase of systemic inflammatory indexes(serum IL-6,TNF-α) and inflammatory factors(MCP-1,MIP1α) levels,aggravate muscle atrophy and cause postoperative decline of hip function.

Key words: hip fracture, mitochondrial DNA, macrophage inflammatory protein 1α, monocyte chemotactic protein 1, muscle atrophy, hip function