Screw and Sheath Tibial Fixation Associated With a Higher Likelihood of Deep Infection After Hamstring Graft Anterior Cruciate Ligament Reconstruction

Background: Hamstring autograft anterior cruciate ligament reconstructions (ACLRs) have exhibited higher infection rates compared with bone–patellar tendon–bone (BPTB) autograft. The reason for this observed difference is unclear, warranting investigation. Purpose: To evaluate the association between tibial fixation, either with or without a sheath and screw construct, and the risk of deep infection after hamstring autograft ACLR, using BPTB autograft as a reference group for comparison. Study Design: Cohort study; Level of evidence, 3. Methods: Using the Kaiser Permanente ACLR Registry, we identified all primary isolated, unilateral, single-bundle ACLRs with a BPTB or hamstring autograft (January 1, 2008, to September 30, 2016). The exposure groups included the following: (1) BPTB ACLR, (2) hamstring ACLR using a screw and sheath construct for tibial fixation (HS with screw and sheath), and (3) hamstring ACLR using a method other than a screw and sheath construct for tibial fixation (HS without screw and sheath). We used logistic regression to evaluate the likelihood of 90-day postoperative deep infection using BPTB autograft as the reference group and adjusting for age, sex, and body mass index. The number needed to be exposed (NNE) was calculated. Results: Of 15,671 ACLRs, 6745 (43.0%) used a BPTB graft, 2852 (18.2%) used HS with screw and sheath tibial fixation, and 6074 (38.8%) used HS without screw and sheath tibial fixation. There were 38 (0.2%) 90-day deep infections: 11 (0.2%) for BPTB, 14 (0.5%) for HS with screw and sheath, and 13 (0.2%) for HS without screw and sheath. Staphylococcus aureus for the BPTB group and Staphylococcus epidermidis in both hamstring groups were the most common infecting organisms. HS with screw and sheath had a higher likelihood of 90-day deep infection compared with BPTB ACLR (odds ratio [OR], 2.87; 95% CI, 1.29-6.38). We failed to observe a difference for HS without screw and sheath compared with BPTB ACLR (OR, 1.23; 95% CI, 0.54-2.77). The NNE was 330 and 2701 for HS with and HS without screw and sheath, respectively. Conclusion: Although the overall infection rate after ACLR is low, the higher likelihood of infections when sheath and screw combined are used for tibial fixation of a hamstring autograft ACLR should be a consideration when this procedure is performed.