Summary

No statistically significant differences in cartilage health was observed in the patellofemoral joint between patients who underwent primary ACLR with or without LET at two years post-operative, as determined via quantitative and qualitative analysis of MRI.

Abstract

Introduction

Several clinical and biomechanics studies have concluded that lateral extra-articular tenodesis (LET) is an effective procedure to control rotational laxity, reducing failure rates when performed with an anterior cruciate ligament reconstruction (ACLR). However, there is question whether the addition of an iliotibial band based LET may cause increased contact pressure in the patellofemoral joint (PFJ) that could potentially lead to cartilage damage. The purpose of the current study was to assess PFJ cartilage status in patients that underwent ACLR with or without LET augmentation using magnetic resonance imaging (MRI). It was hypothesized that 1) the addition of LET at the time of ACLR would have no effect on cartilage health on post-operative two-year MRI; 2) higher cartilage relaxation values would be associated with worse patient reported and functional outcomes at two years post-operatively.

Methods

A subset of patients from the STABILITY 1 randomized controlled trial were included. All patients underwent primary ACLR with a hamstring autograft. The patients were randomized either to receive LET augmentation or not. Cartilage status in the PFJ between ACLR alone group and ACLR+LET group were compared by quantitative MRI (qMRI) and qualitative assessment by ACL osteoarthritis score (ACLOAS) on post-operative two year MRI for surgical and contralateral non-surgical knees. Objective functional outcomes (range of motion (ROM), hop test and isokinetic strength) and patient reported outcome measures including Knee injury Osteoarthritis and Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) score were attained.

Results

Ninety-two patients (43 patients in ACLR group, mean age (±SD) 18.9±3.2 years, 60.5% female, and 49 patients in ACLR+LET group, 18.7±3.2 years, 63.3% females) were included. No significant differences were seen in the mean values (milliseconds) for qMRI for adjusted T1 rho relaxation times in the medial patella (MP) (47.8 vs 47.3), central patella (CP) (45.5 vs 44.1), and lateral patella (LP) (48.2 vs 47.3), and medial trochlea (MT) (54.7 vs 56.4), central trochlea (CT) (53.3 vs 53.1), and lateral trochlea (LT) (54.9 vs 53.9), and adjusted T2 relaxation times in MP (42.2 vs 43.2), CP (42.5 vs 42.7), LP (43.5 vs 43.0), MT (50.9 vs 50.9), CT (51.1 vs 52.0), LT (52.1 vs 52.6) between ACLR and ACLR+LET groups. Similarly, no difference in ACLOAS scores (overall score 10 vs 11, p = 0.99) were observed. An increase in medial patellar T2 relaxation times were associated with decreasing IKDC score (p = 0.046), KOOS symptoms subscale (p = 0.01), and total KOOS score (p = 0.01). Increasing limb symmetry on the hop test was associated with increasing T1 rho (p = 0.04) and T2 (p = 0.01) relaxation in the lateral trochlea.

Conclusion

No difference was found in patellofemoral cartilage health between knees undergoing primary ACLR with hamstring tendon autograft with or without LET at two years post-operative. Statistically significant correlations were found between qMRI relaxation times and functional outcome scores and PROMs, however the correlations were weak and the clinical significance of these changes are undetermined.