The aim of our study was to compare two ultrasound techniques lookout yellow ligament (YL) from the transverse median versus versus paramedian sagittal view.
Materials and methods: we conducted a randomized prospective study of 40 patients proposed for total knee replacement. They were randomized into two groups:
- GM: the identification of the YL is performed in the transverse median section.
- GP: we use the paramedian sagittal section.
for all patients, there is an ultrasound tracking and tranversal median sagittal space epidural puncture. 
Then landmark in each group the YL and its depth is calculated relative to the skin.The epidural anesthesia procedure is thereafter performed according to the conventional technique of loss of resistance. We want the end of the procedure to measure, using the Tuohy trocar, the actual distance between the skin and the YL.
Statistical analysis was performed using SPSS software 22.T
Results: The age (years): GM :64.2 ± 8.4 in GM vs63.7 ± 9.6 in GP (p= 0.43) ; BMI(kg/m2) :25.8 ± 3.6in GM vs26.4 ± 2.9in GP (p=2,3);The median sagittal identification (min): 0.86 ± 0.17in GM vs 0.84 ± 0.19 in GP (p=0.41); The median transverse locating(min):0.41 ± 0.12in GM vs 0.39 ± 0.14 in GP (p=0.37)
The identification of the YL (min) :2.03 ± 0.17in GM vs1.85 ± 0.13in GP (p = 0.019);The duration of the procedure (min) 5.12 ± 0.9 4.93 ± 0.98 0.72; The number of attempts 27/20 23/20 0.27; The volume of 0.125% isobaric bupivacaïne (ml) 37.4 ± 4.6 35.6 ± 3.9 0.29; The incidence of redirection of the needle:25/20in GM vs 1.15 23/20in GP (p=0.49).
Distance between skin and yellow ligament in GM (cm):4.85 ± 0.43 vs 5.16 ± 0.46 in GP (p=0,23). The correlation between calculated and measured distance in GM (p of Pearson=0,84) and in GM (p=0,925).Student´s test comparing the two differences averages is not statistically significant difference with p = 0.22 between GM and GP.
Onset time of sensory block(min): 18.6 ± 2.2in GM vs 17.4 ± 1.8 in GP(p=0.35);installation time of the motor block(min): 28.4 ± 7.4in GM vs 29.2 ± 8.6in GP(p=0.65); Dura breach:3 cases in Gm vs 1 case in GP (p=0.11);The postoperative bleeding(ml) 483.8 ± 127.8 in GM vs 506.4 ± 145.9in GP (p=0.12);Satisfied patients 18/20in GMvs 19/20 in GP (p=0.83).
Conclusion: Ultrasound locating the epidural space, whether performed in the transverse median or paramedian sagittal cut is an easy technique to achieve with a low incidence of complications.

Ultrasonic assessment of phrenic nerve paralysis after interscalene block with ultrasound guidance versus neurostimulation