| Background:Anterior cruciate ligament ACL(ACL)injuries are the most common knee injury,affecting about 85 per 100,000 patients aged 16 to 39,and have been on a steady upward trend in recent years,especially among athletes.Arthroscopic knee anterior cruciate ligament reconstruction(ACLR)is the gold standard for restoring tibia anterior translational and rotational knee stability.Earlier studies found a decrease in subcartilaginous bone density(BMD)in the knee after ACL injury,a significant decrease in BMD in all regions of the affected proximal tibia and distal femur,and a persistent decrease in BMD in the patients’ bilateral calcaneus,knee,and hip joints during recovery from ACL reconstruction.The purpose of this study was to investigate the correlation between bone mineral density(BMD)around the bone tunnel and tendon-bone healing levels and clinical outcomes after anterior cruciate ligament reconstruction.Method:The study included a retrospective study of 204 patients admitted to Qingdao University Hospital between June 1,2018 and June 1,2022 who underwent arthroscopic anterior cruciate ligament reconstruction.MRI imaging and knee function scores were collected on the first day of postoperative knee CT imaging and outpatient follow-up of 6 and 12 months after surgery.Bone density was measured in five regions of interest(region of interest(ROI))of the knee during the first day of postoperative CT examination.Fibrous interzone(FIZ)signal strength was assessed by MRI in the tibia and femoral tunnel as an indicator of the level of tendon healing.Lysholm,Tegner,IKDC subjective function scores and Lachman and Front Drawer tests were collected from 6 and 12 months of outpatient follow-up.The correlation between the enlargement of bone tunnel diameter and the level of tendon bone healing and clinical efficacy in the area of bone tunnel was also studied.Result:1.BMD was highest in cancellous bone of the lateral condyle of the femoral diaphysis and lowest near the midpoint of the tibial plateau.The 5 ROIs surrounding the tunnel were the ROI BMD of the femur tip(ROI 1:390.47±33.42 Hu,ROI 2:330.39±54.75 Hu)and tibia end ROI BMD(ROI 3:148.38 ±70.30 Hu,ROI 4:118.41±69.34 Hu,ROI 5:237.97±78.70 Hu),the ROI BMD of femur was higher than that of tibia(P<0.01),and the difference was statistically significant.2.FIZ signaling intensity was lower in the femoral and tibial tunnel area(F 12=2(1-3),T 12=1(0-2))compared to 6 months after surgery(F 6=3(1-4),T 6=2(0-3))(P<0.01,P<0.01),indicating a gradual decrease in the grade of FIZ in the tendons healing in the bone tunnel over time(P<0.01)compared to 12 months after surgery.3.The functional scores of Lysholm,Tegner and IKDC were(67.6 ± 10.1,2.8 ± 0.9,58.9 ± 9.2),respectively,six months after surgery.Lysholm,Tegner and IKDC scores were(73.38 ± 4.8,84.4 ± 10.1,3.8 ± 1.1),respectively,12 months after surgery.The functional score of the affected limb and knee gradually improved with time(P<0.01,P<0.01,P<0.01),and the results of drawer experiment and axial shift experiment 6 and 12 months after operation confirmed that the knee joint was stable after anterior fork reconstruction in all patients.4.BMD(ROI 1:390.47 ± 33.42 Hu,ROI 2:330.39 ± 54.75 Hu)was significantly negatively associated with FIZ signaling intensity in the femoral tunnel region(r1=-0.52,r2=-0.62).BMD(ROI 3:148.38 ± 70.30 Hu,ROI 4:118.41±69.34 Hu,ROI 5:237.97±78.70 Hu)was negatively associated with FIZ signaling intensity in the tibia tunnel(r3=-0.35,r4＝-0.56,r5=-0.37),and BMD around the bone tunnel was positively associated with post-operative tendon healing levels.5.ROI bone density at the femoral and tibia ends was positively correlated with Lysholm,IKDC and Tenger scores at 6 and 12 months after ACL reconstruction(r>0.37,P<0.01),and not with anterior tibial translational deviation(ATTD)(r<0.3,P>0.01).6.Tendon healing was associated with clinical functional scores:Tegner,Lysholm and IKDC scores were significantly negatively correlated with FIZ scores(r<-0.3,P<0.01).7.Bone tunnel enlargement was not associated with tendon healing or clinical function(r<0.3,P<0.01).8.In the ROI1 group,bone density was high and tendon healing was good in the femoral bone tunnel zone(P<0.001,RR=0.996,95%CL(0.991-1)).ROI4 had a high bone density and good healing of the tendons in the region of the tibial tunnel(P<0.001,RR=0.995,95%CL(0.999-1)).In the ROI5 group,bone density was elevated and knee function recovered well(P<0.001,RR=1.031,95%CL(1.014-1.048)).Conclusion:Bone density distribution was different in different regions,with the highest bone density in the lateral femoral condyle and lowest in the posterior region of the tibia end tunnel.There was a positive correlation between peritunnel bone density and tendon healing after anterior cruciate ligament reconstruction,and peritunnel bone density was positively correlated with clinical outcome.There was a positive correlation between tendon healing level and clinical efficacy.Widening the diameter of bone tunnel was not associated with tendon healing or clinical function. |
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