Abstract:

BACKGROUND: The choice of fixation is an important factor affecting the prognosis of anterior cruciate ligament reconstruction. Endobutton and Rigidfix are two kinds of femoral end suspension fixators which are widely used at present. Their advantages are high fixation strength, large contact area between tendon and bone tunnel, and conducive to tendon-bone healing. However, it is still controversial whether there are differences in clinical efficacy and bone tunnel enlargement between the two fixation methods.

OBJECTIVE: To analyze the outcomes of two different femoral fixation methods (Endobutton and Rigidfix) with hamstring autograft in anterior cruciate ligament reconstruction.

METHODS: A retrospective analysis was performed on the data of 270 cases which accepted the anterior cruciate ligament reconstruction and second arthroscopic look from June 2015 to December 2017. All patients signed the informed consent. This study was approved by the Hospital Ethics Committee. The patients were divided into two groups according to the method of femoral end fixation. The Endobutton femoral fixed reconstruction was performed in Endobutton group (150 cases). The Rigidfix femoral fixed reconstruction was performed in Rigidfix group (120 cases). Reconstruction of anterior cruciate ligament was done using autologous semitendinosus and gracilis tendon. All cases were fixed with Bioabsorbable Interference Screw and AO hollow nail bolt pile fixing screw at the tibial tunnel. The diameter of bone tunnel was also measured by MRI. The knee joint function recovery and stability were evaluated by Lysholm score, International Knee Documentation Committee score, Tenger score table, drawer test, Lachman test, axle shift test, and KT-1000 joint measuring instrument. Second-look arthroscopic evaluation was performed in all patients, focusing on continuity of the reconstructed anterior cruciate ligament, the synovial coverage and the prevalence of abnormal structure at 1 year after surgery. 

RESULTS AND CONCLUSION: (1) All patients were followed up for 14 to 44 months. (2) Tunnel widening was significantly increased in the Endobutton group than in the Rigidfix group at 1 year after surgery (P < 0.05). (3) In both groups after operation, Lysholm scores, Tegner scores, and International Knee Documentation Committee scores had obviously improvement at 1 year after surgery compared with that before surgery (P < 0.05). No significant difference was found between two groups after operation (P > 0.05). (4) At 1 year after surgery, the range of motion of knee joint was not significantly different between the two groups (P > 0.05). (5) There was no significant difference between the two groups in drawer test, Lachman test and axle shift test (P > 0.05). The side-to-side difference of KT-1000 in the Endobutton group was (1.12±1.20) mm, while that of KT-1000 in Rigidfix group was (1.23±0.91) mm. There was no significant difference between the two groups (P > 0.05). (6) Secondary arthroscopic examination showed that there were 1 case of complete graft absorption, 11 cases of graft wear in Endobutton group, 2 cases of complete graft absorption and 15 cases of graft wear in Rigidfix group. There was no significant difference between the two groups (P > 0.05). (7) There were 59 excellent cases, 61 good cases, 30 poor cases in Endobutton group, 47 excellent cases, 49 good cases and 24 poor cases in Rigidfix group. There was no significant difference between the two groups (P > 0.05). (8) The incidence of complication was 2.6% in the Endobutton group and 6.6% in the Rigidfix group, and no significant difference was found between the two groups (P > 0.05). (9) The results suggested that Endobutton and Rigidfix had the same clinical outcome. There was no significant difference in the coverage and continuity of synovial synovial membrane between the second look grafts. However, compared with Rigidfix transverse screw system, Endobutton fixation at the femoral end is more likely to cause bone tunnel enlargement. 

Key words: arthroscope, anterior cruciate ligament, hamstring autograft, second look, fixation, complications