Intraarticular lengths of double-bundle grafts can change during knee flexion: Intraoperative measurements in anatomic anterior cruciate ligament reconstructions

Background: The lengths of the anteromedial bundle (AMB) and posterolateral bundle (PLB) change during knee motion during double-bundle anterior cruciate ligament (ACL) reconstruction. However, the actual intraarticular graft length would be affected by the bone tunnel position and tunnel creation angle during ACL reconstruction. The aim of this study was to investigate the intraarticular length change of the AMB and PLB in patients who underwent anatomic double-bundle ACL reconstruction. Hypothesis: We hypothesized that the PLB would show a more dynamic length change pattern than the AMB during knee flexion at ACL reconstruction. Methods: Thirty-two patients (16 men and 16 women) who had isolated ACL injuries with intact menisci were investigated. Anatomic double-bundle ACL reconstructions were performed using semitendinosus tendon autografts at a mean age of 30.6 years. The graft and tunnel lengths were measured intraoperatively. Intraarticular graft lengths and length changes were calculated at 0˚ and 90˚ of knee flexion during ACL reconstruction. Intraoperative data were collected prospectively, and analyses were performed retrospectively. Results: The intraarticular length of the AMB at 0˚ of knee flexion was 28.1 ± 5.5 mm. At 90˚ of knee flexion, the AMB intraarticular length decreased to 25.6 ± 4.8 mm. The intraarticular length of the PLB decreased to 17.7 ± 4.6 mm at 90˚ of knee flexion compared to 22.0 ± 4.2 mm at 0˚ of knee flexion. Changes in the intraarticular graft length during knee flexion were detected more in the PLB (4.1 mm) than in the AMB (2.0 mm, P = 0.01). Discussion: This study demonstrated that the intraarticular length change of the PLB during knee motion was larger than that of the AMB in anatomic double-bundle ACL reconstructions with semitendinosus tendon autografts and suspensory femoral fixation devices