Summary

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

Abstract

Introduction

Primary anterior cruciate ligament reconstruction (ACLR) using quadriceps tendon (QT) autograft may increase the risk for postoperative loss of extension, although it is unclear if this is due to QT autograft diameter. The purpose of this study was to document the rate of loss of >5° knee extension following QT autograft ACLR and determine associations between loss of extension, QT autograft diameter, and 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 orthopaedic surgeons at a single healthcare institution was performed. Patients undergoing revision ACLR, multi-ligamentous knee surgery, concomitant cartilage procedures, <14 years, or with unavailable preoperative magnetic resonance imaging (MRI) and <6 months follow-up were excluded. Loss of extension was defined using the International Knee Documentation Committee (IKDC) criteria for abnormal knee extension (>5° loss of extension compared to the contralateral knee) 3-12 months after ACLR, or any subsequent surgery for loss of extension. Patients who were unable to achieve terminal knee extension (defined as 0° of extension irrespective of the contralateral knee) were also identified and analyzed. Notch volume was measured by two observers using preoperative MRI scans and a ratio of QT autograft diameter to notch volume was calculated. Univariate and multivariate analyses assessed factors associated with postoperative loss of extension.

Results

A total of 500 patients were identified, of which 333 (67%) were included (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 rate of postoperative loss of extension was 11% (n=37), and 70% (n=26/37) of those with loss of extension underwent a subsequent surgery to restore extension (mean 1.1 ± 1.2 years postoperatively). There was no difference in QT autograft diameter (9.5mm vs 9.6mm, P=0.81), notch volume (6.3cm3 vs 6.5cm3, P=0.70), and the ratio between QT autograft diameter and notch volume (1.6 vs 1.6, P=0.75) between patients with and without postoperative loss of extension. No differences were found in preoperative (P=0.62) and postoperative (2-4 months P=0.99, 5-8 months P=0.71, ≥9 months P=0.95) extension between patients with a QT autograft diameter ≥10mm and <10mm. Only the inability to achieve terminal extension (0°) at the initial preoperative visit was associated with postoperative loss of extension on multivariate analysis (OR 2.23 (95% confidence interval 1.10-4.58), P=0.03).

Discussion And Conclusion

Eleven percent of patients undergoing QT autograft ACLR experienced a loss of >5° knee extension compared to the contralateral knee or required additional surgery to restore extension. QT autograft diameter and notch volume were not associated with postoperative loss of extension among patients who underwent primary QT autograft ACLR. The inability to achieve terminal extension (0°) at the initial preoperative presentation increased the risk of postoperative loss of extension by 2.23-fold. Surgeons may consider the lack of terminal extension preoperatively as a risk factor for postoperative loss of extension following QT autograft ACLR rather than increased QT autograft diameter or decreased notch volume.