Objective To observe the effect of postoperative local injection of platelet-rich plasma(PRP)on patients'early inflammatory response and functional recovery in ankle fractures with lower tibiofibular injuries.Methods Fifty ankle fracture patients with lower tibiofibular injuries admitted to our hospital from January 2017 to December 2022 with postoperative local injection of PRP were selected as the PRP group,and 50 ankle fracture patients with lower tibiofibular injuries undergoing surgical treatment with ligament repair protocols in the same time period with their matched gender and age were selected as the conventional group.We compared the postoperative conditions,postoperative 3 d swelling,postoperative pain visual analogue(VAS)scores and levels of platelet-derived growth factor(PDGF),transforming growth factor β1(TGF-β1),and inflammatory mediators in the two groups,and counted the 24-week postoperative good rate,ankle plantarflexion-dorsiflexion mobility,the quality of the restoration,and the complications in the two groups.Results The swelling grading in the PRP group was lower than that in the conventional group(28 cases of grade Ⅰ,20 cases of grade Ⅱ,and 2 cases of gradeⅢ)in the 3 d postoperative period(15 cases of grade Ⅰ,23 cases of grade Ⅱ,and 12 cases of gradeⅢ),and the VAS scores in the 3 d and 7 d postoperative period[(3.24±0.61)and(2.40±0.42)points]were lower than those in the conventional group[(3.78±0.74)and(2.96±0.55)],and the lower limb weight-bearing activity time(4.01±0.65)weeks,fracture healing time(3.05±0.42)months,and postoperative return to normal work time(3.17±0.47)months were shorter than those in the conventional group[weight-bearing activity time of lower limbs(4.29±0.74)weeks,fracture healing time(3.23±0.48)months,and postoperative return to normal work time(3.40±0.59)months].While the operation time(106.53±19.77)min,number of intraoperative fluoroscopies(14.47±3.23)times,and intraoperative blood loss(84.07±25.60)ml were not statistically different from those of the conventional group[operation time(108.20±18.41)min,number of intraoperative fluoroscopies(14.53±3.06)times,and intraoperative blood loss(86.23±22.17)ml]were not statistically different when compared(P＞0.05).There was no statistical difference in the comparison of preoperative inflammatory mediators,PDGF,and TGF-β1 between the two groups(P＞0.05).In both groups,PDGF was higher and interleukin-6(IL-6),TGF-β1,C-reactive protein(CRP),and tumour necrosis factor-α(TNF-α)were lower at 12 weeks postoperatively compared with the preoperative period(P＜0.05).In the PRP group,the postoperative PDGF was higher than that of the conventional group,and the inflammatory mediators and TGF-β1 were lower than those of the conventional group at 12 weeks postoperatively(P＜0.05).In the PRP group,the postoperative 24 week good rate and ankle plantarflexion-dorsiflexion mobility were higher than that of the conventional group,and the inferior tibiofibular coalition anterior spacing(ITFACS)and inferior tibiofibular coalition posterior spacing(ITFPCS)were lower than that of the conventional group,and there was no statistically significant difference in the rate of complications when comparing the rate with that of the conventional group(P＞0.05).Conclusion Local PRP injection combined with ligament repair protocol for treatment of ankle fractures with lower tibial fibula injuries accelerates patients'early functional recovery and improves the quality of anatomical repositioning,which may be related to the inhibition of inflammatory mediator release and the promotion of bone repair.