Omonbude, D., El Masry, M. A., O'Connor, P. J., Grainger, A. J., Allgar, V. L., Calder, S. J. Measurement of joint effusion and haematoma formation by ultrasound in assessing the effectiveness of drains after total knee replacement: A prospective randomised study. Journal of Bone & Joint Surgery - British Volume 2010; 1: 51-5