Transient hypercoagulability during the perioperative period of anterior cruciate ligament reconstruction: A thromboelastogram comparison between hamstring autografts and synthetic ligaments

Background Deep vein thrombosis following primary anterior cruciate ligament reconstruction is a complication that is frequently underestimated in clinical practice; its core pathophysiological basis involves perioperative tissue injury and systemic coagulation homeostasis imbalance induced by ischaemia-reperfusion. Although autologous hamstring tendon grafts are widely used, the additional soft tissue damage associated with the harvesting of multiple tendon strands is thought to potentially exacerbate the hypercoagulable state during the acute phase. In contrast, synthetic grafts based on polyethylene terephthalate (PET) completely avoid donor site trauma; however, their non-biological nature has raised theoretical concerns regarding the activation of endogenous coagulation pathways upon contact. Currently, there remains a lack of quantitative comparisons and definitive conclusions regarding the specific effects of these two distinct graft options and their associated surgical trauma on the micro-coagulation dynamics during the perioperative period. Methods This retrospective cohort study included 407 patients who underwent primary isolated anterior cruciate ligament reconstruction, comprising 293 patients in the autologous tendon group and 114 in the synthetic ligament group. To eliminate the interference of drugs on the fibrinolytic system and the natural coagulation cascade, the prophylactic use of tranexamic acid was strictly avoided across the entire cohort. In the autograft group, a combined harvest of the semitendinosus and gracilis tendons was uniformly employed. The study quantified the duration of surgery and the decrease in haemoglobin levels across groups, and systematically assessed patients’ baseline Caprini thrombosis risk scores. Hemorheological monitoring spanned three key time points: preoperatively, on postoperative day 1, and on postoperative day 3. Core viscoelastic parameters from thromboelastography and routine biochemical coagulation indices were extracted, and repeated measures analysis of variance was employed to evaluate the interaction effects of time course and graft type. Hypothesis : In primary anterior cruciate ligament reconstruction, the activation of the systemic coagulation system resulting from the additional soft tissue trauma and ischaemic load associated with the harvesting of the multifasciculated semitendinosus and gracilis muscles is significantly greater than the foreign body contact effect of synthetic polyethylene terephthalate (PET) materials, thereby inducing a more pronounced and transient hypercoagulable shift. Results There were no statistically significant differences between the two groups in terms of baseline characteristics such as age, BMI, and Caprini score (all P > 0.05). About surgical trauma, the autologous tendon group exhibited significantly longer operative times (42.6 ± 9.4 vs. 32.5 ± 7.8 min, P < 0.001) and greater decreases in haemoglobin levels (13.9 ± 5.2 vs. 7.8 ± 4.1 g/L, P < 0.001) compared with the synthetic ligament group. On postoperative day 1, the difference in prothrombin time (PT) between the two groups was not statistically significant (10.9 ± 1.2 vs. 11.12 ± 1.0 s, P = 0.061); however, thromboelastography (TEG) revealed that the comprehensive coagulation index (CI: 2.45 ± 1.12 vs. 0.82 ± 0.94, P < 0.001) and maximum amplitude (MA: 69.1 ± 7.8 vs. 60.0 ± 5.1 mm, P < 0.001) were both significantly higher in the autologous tendon group than in the synthetic ligament group, and returned to baseline levels (CI: 0.30 ± 0.85) by postoperative day 3 in the autologous group. Multivariate regression analysis confirmed that the decrease in haemoglobin (P < 0.001) and baseline Caprini score (P < 0.001) were independent predictors of postoperative hypercoagulable states as indicated by TEG. With regard to clinical outcomes, the incidence of early postoperative distal deep vein thrombosis was significantly higher in the autologous tendon group than in the artificial ligament group (4.4% vs. 0.9%, P = 0.045). Conclusion This study demonstrates that, in the acute postoperative period following primary anterior cruciate ligament reconstruction, autologous grafts derived from the multifasciculated semitendinosus and gracilis muscles induce a more pronounced transient hypercoagulable state than synthetic ligaments. This microhaemodynamic differentiation is primarily driven by additional tissue trauma and blood loss, rather than foreign body activation by synthetic implants. For patients with a high Caprini thrombosis risk score, clinicians should incorporate the traumatic effects of graft harvesting as a key consideration when formulating deep vein thrombosis prevention strategies. Study design: Retrospective cohort study; evidence grade 3.