PurposeThis study set out to assess the clinical and radiographic outcomes and the extent of synovial coverage on second-look arthroscopy of anterior cruciate ligament (ACL) reconstruction using a remnant-preserving and re-tensioning technique to easily cover the graft with a remnant.MethodsForty-three subjects with ACL rupture underwent remnant-preserving and re-tensioning ACL reconstruction using a free tendon Achilles allograft between 2011 and 2013. The clinical outcomes were assessed by Lysholm knee score, Lachman stress test, pivot shift test, International Knee Documentation Committee (IKDC) classification, and Tegner Activity Scale score. Side-to-side difference (SSD) was assessed on stress radiographs. The extent of synovialization was evaluated on second-look arthroscopy.ResultsThe mean Lysholm score was 54 ± 11 before surgery and 94 ± 5 at the last follow-up (p < 0.001). On Lachman stress test, 42 subjects had grade 0 or 1 on the Lachman stress test, and 42 had grade 0 or 1 on the pivot shift test. Forty-one subjects had IKDC classification A or B; two were classified as C or D. The median Tegner Activity Scale score was 6.5 (range 5–9) before injury and 6 (range 4–8) at the last follow-up (p = 0.048). Mean SSD on stress radiographs was 9.9 ± 2.6 mm preoperatively and 1.0 ± 1.7 mm at the last follow-up (p < 0.001). In the assessment of the extent of synovial coverage of the graft, 39 subjects were in group 1 (>75 %) for synovial coverage of the graft, three were in group 2 (50–75 %), and one was in group 4 (≤25 %).ConclusionsThe remnant-preserving and re-tensioning technique resulted in satisfying short-term results clinically and radiologically and good synovial coverage on second-look arthroscopy.Level of EvidenceCase series, Level IV.