Summary

Female sex, a history of previous knee surgery and a transtibial femoral tunnel drilling technique are associated with a higher risk of arthrofibrosis following primary ACL reconstruction.

Abstract

Introduction

Arthrofibrosis is a less common complication following anterior cruciate ligament (ACL) reconstruction. It is unclear what factors increase the risk of arthrofibrosis, however there are concerns that undergoing early surgery may be associated with arthrofibrosis. The aim of this study was to identify the patient and surgical risk factors for arthrofibrosis following primary ACL reconstruction.

Methods

Prospective data recorded by the New Zealand ACL Registry was analyzed and cross referenced with data from the Accident Compensation Corporation (ACC), which is the New Zealand Government’s sole funder of ACL reconstructions and any subsequent surgery. Primary ACL reconstructions performed between April 2014 and December 2019 were analyzed, allowing for a minimum follow-up of two years. Patient and surgical data including age, sex, time from injury-to-surgery, a history of previous knee surgery, graft type, concomitant meniscal injury and femoral tunnel drilling technique were analyzed as recorded in the New Zealand ACL Registry. The ACC database was used to identify patients who underwent a subsequent reoperation with review of operation notes to identify those who had a reoperation for “arthrofibrosis” or “stiffness”. The rates of arthrofibrosis were calculated for each patient and surgical factor and compared via Chi-Square test. A multivariate Cox regression survival analysis was performed to identify the risk factors for reoperation for arthrofibrosis. Hazard ratios (HR) with 95% confidence intervals (CI) were computed.

Results

Of 9617 primary ACL reconstructions analyzed, 215 patients underwent a subsequent reoperation for arthrofibrosis (2.2%). A higher risk of arthrofibrosis was observed in female patients (adjusted HR = 1.67, 95% CI 1.22 – 2.27, p = 0.001), patients with a history of previous knee surgery (adjusted HR = 1.97, 95% CI 1.11 – 3.50, p = 0.021) and when a transtibial femoral tunnel drilling technique was used (adjusted HR = 1.55, 95% CI 1.06 – 2.28, p = 0.024). Patients who underwent early ACL reconstruction within 6 weeks of their injury did not have a higher risk of arthrofibrosis when compared to patients who underwent surgery more than 6 weeks after their injury (3.5% versus 2.1%, adjusted HR = 1.56, 95% CI 0.97 – 2.50, p = 0.07). Age, graft type and concomitant meniscal injury did not influence the rate of arthrofibrosis.

Discussion And Conclusion

Female sex, a history of previous knee surgery and a transtibial femoral tunnel drilling technique are risk factors for arthrofibrosis after primary ACL reconstruction. Undergoing early ACL reconstruction within 6 weeks of ACL rupture does not increase the risk of arthrofibrosis.