Effect of Joint Infection After Arthroscopic Single-Bundle ACL Reconstruction With Autologous Hamstring Tendon: A Retrospective Matched MRI Study

BACKGROUND: Joint infection after anterior cruciate ligament (ACL) reconstruction is a rare but serious complication. PURPOSE: To assess the effect of joint infection on the graft, cartilage, and bone tunnel using magnetic resonance imaging (MRI) after arthroscopic single-bundle ACL reconstruction with autologous hamstring tendons. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: This retrospective matched cohort study included 26 patients who underwent arthroscopic single-bundle ACL reconstruction with hamstring tendon graft at the authors’ institute between January 2002 and December 2017 and developed postoperative joint infection. These patients were matched 1:3 to patients who did not sustain joint infection after ACL reconstruction (control group). MRI scans were collected at the time of follow-up. The following parameters were evaluated: graft signal-to-noise quotient (SNQ); graft signal intensity at the bone-graft interface and within the knee joint; bone tunnel enlargement at the tunnel aperture, midsection, and exit of the tibial and femoral tunnels; and cartilage integrity. RESULTS: The average follow-up time was 47.8 months in the infection group and 48.5 months in the control group. Compared with the control group, the infection group had a significantly higher SNQ (20.01 ± 12.08 vs 7.61 ± 6.70; P = .014) as well as a higher signal intensity at the bone-graft interface (P = .037) and higher Howell grade (P = .031). The mean enlargement at the femoral tunnel aperture was 31.20% ± 26.76% in the infection group and 19.22% ± 20.10% in the control group (P = .037). The articular cartilage of the patellofemoral and lateral femorotibial joints showed more degenerative change in the infection group. CONCLUSION: Study findings indicated that graft ligamentization and incorporation graft maturity were inferior in patients who experienced a joint infection after ACL reconstruction compared with patients who did not.