Summary

To study the anterolateral ligament of the knee using ultrasonogram and determine its morphology and clinical relevance with respect to correlation with high grade pivot shift

Abstract

Introduction

Anterolateral ligament (ALL) of the knee joint has gained popularity amongst arthroscopic surgeons around the world since the time of its resurgence. The importance of this ligament and correlation with high grade pivot shift is debatable.

Aim

To study the anterolateral ligament of the knee using ultrasonogram and determine its morphology and clinical relevance.
Material & Methods: 45 consecutive skeletally mature patients with ACL insufficiency underwent ultrasound examination of their knee joint with high resolution linear probe (12MHz). The study was done by a single senior musculoskeletal radiologist blinded to the clinical findings. The length and thickness of ALL and the presence or absence of tear were documented. A single experienced arthroscopic knee surgeon blinded to the ultrasound findings examined their knees under anaesthesia for pivot shift.

Results

Mean age was 31years. Male : Female ratio was 8:1, Right:Left ratio was 1:0.7. Ultrasound examination identified the anterolateral ligament in all cases (100%) and revealed tear in 8 knees (17.7%). Clinical examination in these knees found high grade pivot shift in 6 and a negative pivot shift in 2 knees. Conversely 6 knees, with normal ALL had high grade pivot shift. The mean length of ALL was 35.42 ± 2.6mm with thickness of 1.5 ± 0.2 mm. Ultrasound had a sensitivity of 50% and specificity of 93.9 % to identify the tear. It’s Positive predictive value was 75% and negative predictive value was 83%.

Conclusion

Ultrasound is a simple cost effective and highly specific diagnostic modality to identify and diagnose ALL tear. But there was no significant correlation with high grade pivot shift and ALL tear.