Anatomic double-bundle anterior cruciate ligament reconstruction could not achieve sufficient control of pivot-shift when accompanying tibial tunnel coalition

Abstract

Purpose: To evaluate the effect of tibial tunnel coalition on knee rotatory laxity and clinical outcomes after double-bundle (DB) anterior cruciate ligament (ACL) reconstruction.

Methods: Forty-one patients who underwent anatomic DB ACL reconstruction were included prospectively. Three-dimensional computed tomography of the knee joint was obtained at approximately 1 year postoperatively to determine if tunnel coalition occurred. After excluding seven cases of femoral tunnel coalition, two groups were established based on the existence of a tibial tunnel coalition. The pivot-shift test was quantitatively evaluated on the basis of tibial acceleration preoperatively and at 1 year postoperatively. Two subjective scores, the International Knee Documentation Committee (IKDC) subjective and Lysholm scores, were also collected. The pivot-shift measurement and subjective scores were compared between the ACL-reconstructed knees with and without tibial tunnel coalition. The independent t test, Pearson's chi-square test, and Student t tests were used in data analysis.

Results: Twenty-one knees had tibial tunnel coalition (group C), whereas 13 knees did not have tunnel coalition(group N). Pivot-shift was significantly diminished postoperatively in both groups on the basis of the clinical examination and quantitative evaluations (p < 0.05). However, there was a small but significant difference in tibial acceleration demonstrating larger pivot-shift in group C (1.0 ± 0.6 m/s²) than in group N (0.5 ± 0.3 m/s², p < 0.05). No significant difference was observed in the IKDC subjective and Lysholm scores (both n.s.).

Conclusion: When the tibial tunnel coalition occurs after DB ACL reconstruction, knee rotatory laxity may not be restored in ACL-reconstructed knees, as expected in those without tunnel coalition. It is recommended that two tibial tunnels should be created separately when performing DB-ACL reconstruction to achieve better control of rotatory knee laxity.

Level of evidence: III.

Keywords: Double-bundle anterior cruciate ligament reconstruction; Electromagnetic measurement system; Pivot-shift test; Quantitative measurement; Tunnel coalition.