To investigate the knee joint stability, function and three-dimensional gait kinematics after anterior cruciate ligament reconstruction.

A retrospective analysis of 270 cases of ACL reconstruction and secondary arthroscopy was performed in the sports department of Foshan Traditional Chinese Medicine from July 2015 to July 2017.There were 164 males and 106 females. Lysholm score, International Knee Documentation Committee(IKDC) score, Tenger scale, knee injury and osteoarthritis outcome (KOOS) score, Lachman test, axle shift test and KT-1000 were used to evaluate function and stability of the knee. Six free domofmotion(6-DOF)was compared to evaluate the postoperative knee joint function objectively. Graft continuity, graft synovial coverage, and abnormal structure were observed in the joint during second look. The relationship between the morphology of the graft and the function and kinematics feature of the knee was analysed. The rate of return-to-sport (RTS) was caculated and the influencing factors were compared with those failed to RTS. Enumeration data were compared using the chi-square test, the quantity data were compared by t test.

The average follow-up time of 270 patients was (26±11) months. One patient developed postoperative infection, which was cured by arthroscopy, catheterization and drainage. The other patients had no complication such as infection or graft absorption. At the last follow-up, Lysholm score, IKDC subjective score, Tegner score, KOOS (function score, quality of life, pain score, daily life, symptom score), IKDC objective evaluation, axial shift test, Lachman test and KT-1000 side to side difference in the last follow-up of all the patients were significantly improved compared with those before operation (t=71.13, 15.08, 45.94, 15.73, 21.72, 15.25, 23.69, 36.30, 532.19, 432.00, 444.30, 214.65, all P<0.05). During the second look, 191 patients had intact anterior cruciate ligament while other 79 patients had reconstructed ligament with partial tear. ACL of 230 patients demonstrated good tension while the others showed a loose ligament. ACL of 220 patients had good synovial coverage and the others showed poor synovial coverage. At the last follow-up, the 6-DOF kinematic parameters (ranges of adduction-abduction angles, internal-external angles, flexion and extension, proximal-distal translation, lateral-medial translation, anterior-posterior translation) of all the patients were significant superior than those before the operation(t=2.54, -8.67, 11.06, -17.44, 2.80, 2.94, all P<0.05). The Lysholm score, IKDC score, Tegner score, KT -1000 side-to-side difference, the ranges of internal-external angles, anterior-posterior translation of 6-DOF kinematic parameters of knee joint of superior synovium coverage group were better than those of poor synovium coverage group(t=13.50, 7.69, 20.05, 12.69, all P<0.01; t=3.97, 8.23, both P<0.05). The range of flexion and extension angles, adduction-abduction angles, lateral-medial translation, proximal-distal translation in the optimal synovium coverage group were similar to those in the poor synovium coverage group (P> 0.05). Among 270 patients, 98 patients returned to exercise, the rate of return to exercise was 36.3%.

ACL reconstruction with autogenous hamstring tendon can obtain better stability and function of knee joint. However, the rate of patients returning to exercise is low, which is the key problem to be solved in the future.