Abstract: BACKGROUND: The imaging evaluation of anterior cruciate ligament reconstruction mostly through two-dimensional X-ray has disadvantages of non-solid and large measurement error, while three-dimensional reconstructive CT (3D-CT) has higher accuracy for postoperative evaluation.
OBJECTIVE: To evaluate the accuracy of bone tunnel position and graft status after anterior cruciate ligament near-isometric reconstruction measured by 3D-CT and X-ray. 
METHODS: From January 2016 to December 2019, 31 patients with arthroscopic anterior cruciate ligament reconstruction were selected from the Third Affiliated Hospital of Guangzhou University of Chinese Medicine, including 28 males and 3 females, at the age of 20-47 years. All patients were subjected to anterior medial approach to locate the bone tunnel of femur and anterior cruciate ligament near-isometric reconstruction. 3D-CT and X-ray examination were performed within one week after the operation to observe the condition of graft and bone tunnel. The position of bone tunnel in tibia and femur was measured by Klos method and Bernard method respectively. The trial was approved by the Ethics Committee of the Third Affiliated Hospital of Guangzhou University of Chinese Medicine.
RESULTS AND CONCLUSION: (1) 3D-CT clearly showed the bone tunnel after anterior cruciate ligament reconstruction. The 31 patients had complete bone tunnel wall, (21.71±2.16) mm for femoral end graft and (14.23±1.78) mm for tibial end graft (excluding extrusion screw part). The internal fixator and graft ligament could also be observed. (2) X-ray films showed that the position of tibial tunnel was (44.17±5.23)% in sagittal plane and (43.05±4.58)% in coronal plane. The position of femoral tunnel was (28.75±4.59)% in Blumensaat line level and (38.23±8.71)% in height from the top of intercondylar fossa. 3D-CT showed that the position of tibial tunnel was (42.41±6.93)% in sagittal plane and (43.66%±4.12)% in coronal plane; the position of femoral tunnel was (32.41±6.33)% in blumensaat line level and (41.53±6.51)% in height from the top of intercondylar fossa. There was significant difference in tunnel position between the two methods at Blumensaat line level (P=0.011). (3) The results show that there are some differences between 3D-CT and X-ray films in the evaluation of bone tunnel position after anterior cruciate ligament near-isometric reconstruction. 3D-CT measurement can objectively and accurately reflect the condition of bone tunnel and graft state. 

Key words: bone, graft, anterior cruciate ligament, reconstruction, bone tunnel, 3D-CT, X-ray film