Background: Complications and adverse events after anterior cruciate ligament (ACL) reconstruction are well known, but they have been underestimated in previous studies. Purpose: To describe the complications and adverse events after ACL reconstruction within a 2-year follow-up and analyze them in relation to the type of graft. Study Design: Cohort study; Level of evidence, 3. Methods: From 2000 to 2012, 958 patients with an isolated ACL injury underwent surgery by a single knee surgeon. ACL reconstruction was performed with the medial portal technique for the femoral tunnel and the use of bone–patellar tendon–bone (BPTB) or hamstring tendon graft. Patients were reviewed at 6 weeks and 3, 6, 12, and 24 months after surgery with the International Knee Documentation Committee score, plain radiographs, and the KT-1000 arthrometer. Results: Of 958 patients enrolled, 147 (15%) were lost at last follow-up. The 2 groups (bone–patellar tendon–bone [n = 257] and hamstring [n = 554]) were similar regarding the mean age at the time of surgery and preoperative anterior laxity. The main complications were as follows: anterior knee pain (n = 130 of 811, 16%), stiffness (n = 72, 8.8%), secondary meniscal lesions (n = 59, 7.2%), pain attributed to fixation (n = 79, 9.7%), ACL rerupture (n = 47, 5.7%), contralateral ACL ruptures (n = 24, 3%), patellar fractures (n = 3, 0.3%), infections (n = 9, 1%), and thromboembolic complications (n = 5, 0.6%). There was no significant difference between the grafts with respect to the frequency of joint stiffness, secondary meniscal lesions, or anterior knee pain. During the first 2 postoperative years, the percentage of patients with anterior knee pain was higher in the patellar tendon group (23.3% vs 12.6%, P < .001); however, this difference was not significant after the 2-year interval (3.1% vs 2.5%, P = .63). The percentage of patients with a rerupture of the graft was significantly lower in the patellar tendon group than in the hamstring group (25 of 811 [3.1%] vs 57 of 811 [7%], P = .023). Similar results were recorded regarding the pain related to the hardware material (7 of 811 [0.8%] in the BPTB group vs 113 of 811 [13.9%] in the hamstring group, P = .001). The percentage of ACL ruptures contralateral to the repair was higher in the patellar tendon group (41 of 811 [5%] vs 17 of 811 [2%], P = .016). Conclusion: The total rate of complications after an ACL reconstruction was 39%, and the surgical revision rate for any reason was 28%. Problems with the hardware material were more frequent in the hamstring group, leading to an increased rate of surgical revision. Anterior knee pain was initially higher in the patellar tendon group, but there was no significant difference in a 2-year interval. The rerupture rate was statistically higher in the hamstring group.
