2017 ISAKOS Biennial Congress ePoster #1062

 

Kinematic Changes Following ACL Reconstruction Detected By QMR Imaging and their Relationship to Knee Function

Qi Li, PhD, MD, Chengdu, Sichuan CHINA
Keiko Amano, MD, San Francisco, CA UNITED STATES
Matthew Tanaka, MD, San Francisco, CA UNITED STATES
Valentina Pedoia, PhD, San Francisco, CA UNITED STATES
Xiaojuan Li, PhD, San Francisco, CA UNITED STATES
C. Benjamin Ma, MD, San Francisco, CA UNITED STATES

West China Hospital, Sichuan University, chengdu, sichuan, CHINA

FDA Status Cleared

Summary

Increased anterior positioning of the tibia in the injured knee at 3Y after ACL reconstruction were observed, which may cause less improved knee function. Our results suggest that more attention should be paid to the rehabilitation and sports activities between 1Y and 2Y after ACL reconstruction.

Abstract

Introduction

Knee kinematic changes after ACL injuries. Abnormal knee kinematics may lead to post-traumatic osteoarthritis and decrease of knee function. ACL reconstruction was supposed to restore the original knee kinematics and improve knee function and activity level. However, kinematic changes after ACL reconstruction may still persist even when the patients went back to sports normally. The goal of this study was to quantify subtle kinematic changes of ACL-injured knees 3-years after ACL-reconstruction using quantitative MR imaging techniques, and to explore their relationship to knee function.

Methods

26 patients with acute ACL injuries were included in this prospective cohort study (mean age, 29.6±7.6 years). Images of the bilateral knees were acquired using a 3-Tesla MRI-scanner at baseline (BL, post-injury and before ACL reconstruction), and 6 months (6M), 1 year (1Y), 2 years (2Y) and 3 years (3Y) after ACL reconstruction. The imaging protocol included sagittal T2 FSE images with load (25% of the patient’s body weight) applied axially in the extended knee position. Knee injury and Osteoarthritis Outcome Score (KOOS) were completed at all visits. A tibial and femoral coordinate system was established after segmenting the bones in 2D FSE images in order to define the tibial position (TP) relative to the femur using an in house Matlab-based program. Side-to-side difference of TP (TP-SSD) was calculated by subtracting the contralateral side measurements from the injured side. Delta KOOS was calculated by subtracting the KOOS of BL from that of 3Y. Paired T-tests were used for comparing TP between the injured and contralateral knee at each visit, and longitudinal changes in KOOS, TP-SSD between baseline and follow-ups. Partial correlations were used to determine correlation between TP and KOOS, while controlling for age, gender, and body mass index (BMI).

Results

TP: TP of the injured knee was significantly more anterior than the contralateral uninjured knee at BL, 6M, 1Y, 2Y and 3Y(p<0.05) (Fig 1). TP of the injured knee was more anterior at 3Y and 2Y than at 1Y (p<0.005), while no difference in the injured knee TP was observed between 2Y and 3Y (p=0.240). TP-SSD was significantly low at 1Y, compared to BL (p=0.013), 2Y (p=0.023) and 3Y (p=0.001)(Fig 2). KOOS: At 3Y, all the KOOS were significantly higher than that at BL (p<0.01) and 1Y (p<0.01). Correlation: There was no correlation between KOOS and TP-SSD at 3Y. But TP-SSD at 3Y was negatively correlated with delta KOOS Pain Score, delta KOOS Symptom Score, delta KOOS Activities of Daily Life Score and delta KOOS Sports Score from BL to 3Y (Table 1).

Discussion

Our results suggest that ACL reconstruction was not able to completely restore the normal TP. Although TP and TP-SSD decreased from BL to 1Y after ACL reconstruction, suggesting improved joint biomechanics due to the surgical reconstruction, it increased again from 1Y to 2Y and 3Y. In particular, this increase was significant from 1Y to 2Y, but not from 2Y to 3Y. Patients with ACL reconstruction normally go back to sports activities by 1Y after the surgery. The KOOS increased significantly from 1Y to 3Y generally, which show that the patients in this cohort got significantly recovery of their knee function and symptoms at 3Y after ACL reconstruction., while the negative correlation between TP-SSD at 3Y and Delta KOOS (BL to 3Y) may suggest that subjects with looser knees after ACL reconstruction have less improvement in function and symptoms.