Summary

Graft diameter is not associated with postoperative loss of extension among patients who undergo primary quadriceps tendon autograft ACL reconstruction.

Abstract

Introduction

An association between large graft diameter and loss of extension following anterior cruciate ligament reconstruction (ACLR) may exist. However, few studies have specifically investigated this association with quadriceps tendon (QT) autograft ACLR. The purpose of this study was to determine the association between loss of extension following primary QT autograft ACLR and graft diameter, while also accounting for intercondylar notch volume.

Methods

A retrospective review of a consecutive series of patients undergoing primary ACLR with QT autograft between January 2014-December 2021 by seven fellowship trained sports medicine surgeons at a single large health care institution was performed. Exclusion criteria included revision ACLR, multiligamentous knee surgery, age <14 years, an unavailable preoperative magnetic resonance imaging (MRI) scan, and less than 6 months follow-up. Loss of extension was defined using the International Knee Documentation Committee (IKDC) criteria for abnormal range of motion (ROM) of the knee (defined as an extension deficit >5° compared to the contralateral knee) 3-12 months after ACLR, or any subsequent surgery for an isolated extension deficit. Notch volume was measured by two observers using preoperative T2 or proton density (PD) weighted MRI scans. Graft diameter was estimated using the average of reported femoral and tibial tunnel diameters. Statistical analyses included Chi square and Fisher’s exact tests for categorical variables, or Mann Whitney U tests and independent samples t-test for nonparametric and parametric variables, respectively.

Results

A total of 1,714 primary ACLRs were initially identified, of which 333 met inclusion criteria (mean age 22.8 ± 7.7 years, 151 (45%) female). The mean follow-up was 1.6 ± 1.3 (range 0.5 – 9.5) years. The mean interobserver reliability for measurements of notch volume was excellent (intraclass correlation coefficient = 0.98, 95% confidence interval 0.95 – 0.99). The rate of postoperative loss of extension was 11% (n=37), and 70% (n=26) of those with loss of extension underwent a subsequent surgery to restore extension deficits. Demographic and surgical variables were comparable between patients with and without loss of extension. No significant differences were detected between patients with and without loss of extension with respect to graft diameter (9.5mm vs 9.6mm, P=0.81), notch volume (6.3cm3 vs 6.5cm3, P=0.70), and the ratio between graft diameter and notch volume (1.6 vs 1.6, P=0.75). ROM was comparable between patients who underwent ACLR with a graft diameter ≥10mm and <10mm at all postoperative intervals.

Discussion And Conclusion

Graft diameter is not associated with postoperative loss of extension among patients who undergo primary QT autograft ACLR. Accounting for notch volume also did not reveal any significant differences. Surgeons may utilize this information when evaluating the optimal QT harvest diameter for primary ACLR.