Tibial tunnel compaction-drilling technique reduces tibial tunnel enlargement and improves knee stability in ACL reconstruction with hamstring autografts: a retrospective cohort study

Background The application of tibial tunnel compaction-drilling technique in anterior cruciate ligament reconstruction (ACL-R) is controversy. The purpose of this study was to evaluate the impact of tibial tunnel compaction-drilling technique and extraction-drilling technique used in single‑bundle ACL reconstruction on bone tunnel enlargement value, ACL graft maturation and clinical outcomes. Methods In this retrospective cohort study, 62 patients receiving ACL-R were screened and divided into two groups based on the technique of tibial tunnel drilling: compaction-drilling group (CD group, n = 31) and extraction-drilling group (ED group, n = 31). The bone tunnel enlargement was analysed based on the multislice computerised tomography at 12 months postoperatively. The ACL graft maturation was evaluated by the signal/noise quotient (SNQ) value on magnetic resonance imaging at 12 months postoperatively. Subjectively clinical outcomes were assessed by Lysholm score and International Knee Documentation Committee (IKDC) subjective score at 12 months postoperatively. Pivot-shift test was performed at 12 months postoperatively. The instrumental laxity measurement using the KT-1000 arthrometer was performed at 12 and 24 months postoperatively. Results The tibial bone tunnel diameters were enlarged by 9–15% in CD group ( p  < 0.001) and enlarged by 15–22% in ED group ( p  < 0.001). The CD group showed significantly smaller bone tunnel enlargement value than the ED group at 12 months follow up ( P  < 0.05). In addition, significantly decreased KT-1000 measurement was found in CD group at 12 months (3.7 ± 1.8 vs. 5.0 ± 1.8 mm) ( P  = 0.003) and 24 months follow up (3.4 ± 1.6 vs. 5.4 ± 2.0 mm) ( P  < 0.001) compared to the ED group. No statistically significant differences of the SNQ value ( p  = 0.255), IKDC subjective score ( p  = 0.599) and Lysholm score ( p  = 0.378) were found between two groups at 12 months postoperatively. Conclusion This study demonstrated that bone tunnel compaction-drilling technique could reduce the tibial bone tunnel enlargement and improve knee stability compared with extraction-drilling technique in ACL-R objectively.