The importance of continuous remnant preservation in anterior cruciate ligament reconstruction

Purpose Selective anteromedial or posterolateral bundle reconstruction is recognized as a treatment modality in partial anterior cruciate ligament (ACL) reconstruction (ACLR) with a biomechanically sufficient ACL remnant. However, there is paucity in literature investigating clinical outcomes of standard ACLR with preservation of residual continuous but biomechanically insufficient ACL tissue. The aim of this study was to investigate the influence of preservation of residual continuous but biomechanical insufficient ACL tissue in standard ACLR on complication and repeat surgery rate, and patient reported and clinical outcome. Methods The retrospective cohort comprised 134 patients (age 23 ± 7 years; Tegner 6 ± 3) with an isolated acute ACL tear. In 67 patients, residual continuous but biomechanically insufficient ACL tissue was present and preserved based on visual inspection, probing of the ACL tissue and Lachman test under arthroscopic view (standard reconstruction with tissue preservation; SRTP). These patients were matched to 67 patients that underwent ACLR where no residual ACL tissue could be preserved (standard reconstruction; SR) based on gender, age and chondral and/or meniscal status. Clinical failure (recurrent instability, pathological ACL graft laxity and/or ACL graft discontinuity), other complication and repeat-surgery rate within index surgery and 1-year and within index surgery and 2-year follow-up, and patient reported and clinical outcomes at 1-year and at 2-year follow-up were compared. Results A statistically significant lower clinical failure rate within index surgery and 1-year (SRTP, 3%; SR, 13%; P = 0.028) and within index surgery and 2-year follow-up (SRTP, 3%; SR, 23%; P = 0.001), and revision ACL surgery rate within index surgery and 1-year (SRTP, 2%; ST, 10%; P = 0.029) and within index surgery and 2-year follow-up (SRTP, 2%; SR, 18%; P = 0.001) was found in the SRTP group. No statistically significant differences were found for other investigated outcomes in patients that were without clinical failure. Conclusion This study shows that in ACLR surgery, preservation of residual continuous but biomechanical insufficient ACL tissue might lead to lower clinical failure rate and ACL revision surgery rate within index surgery and 1-year, and within index surgery and 2-year follow-up compared to standard ACLR where no residual continuous ACL tissue could be preserved. Level of evidence III.