Does the McRoberts’ manoeuvre need to start with thigh abduction? An innovative biomechanical study

David Desseauve (1) , Laetitia Fradet (2) , Robert Gherman , Yosra Cherni (2) , Bertrand Gachon (1) , Fabrice Pierre (1)

1 Department of Gynecology-Obstetric and Reproductive Medicine, CHU Poitiers, 86000 Poitiers, France
2 RoBioSS - Robotique, Biomécanique, Sport, Santé [Institut Pprime]

Background
Guidelines and description about the achievement of the McRoberts manoeuvre are discordant, particularly concerning the need for abduction before the beginning of the manoeuvre. We sought to compare the biomechanical efficiency of the McRoberts’ manoeuvre, with and without thigh abduction.
Methods
In a postural comparative study, twenty-three gravidas > 32 weeks of gestational age and not in labour were assessed during three repetitions of two McRoberts’ manoeuvre that differed in terms of starting position. For the (i) McRoberts, the legs were initially placed in stirrups; for the (m) McRoberts, the legs were resting on the bed, with thighs in wide abduction. For each manoeuvre, flexion of the plane of the external conjugate of the pelvis on the spine (ANGce), hip flexion and abduction, were assessed using an optoelectronic motion capture system. Lumbar curve were assessed with Epionics Spine® system. Temporal parameters including movement duration or acceleration of the external conjugate were also computed. All values ​​obtained for the two types of manoeuvres were compared using a Wilcoxon matched-pairs signed-ranks test. The significance level was defined as p < 0.05.
Results
The starting position of McRoberts’ otherwise had no effect on the maximum ANGce (p = 0.199), the minimal lordosis of the lumbar curve (p = 0.474), or the maximal hip flexion (p = 0.057). The other parameters were not statistically different according to the starting position (p > 0.005).
Conclusion
Regardless of the starting position, the McRoberts’ manoeuvre allows ascension of the pubic symphysis and reduction of the lumbar lordosis. This results imply that the McRoberts’ manoeuvre could be performed with the legs initially placed in the stirrups.

Mots clés: Shoulder dystocia; McRoberts manoeuvre; Biomechanical; Motion capture system; Lumbar curve

Domaines: Mécanique des fluides [physics.class-ph]; Matériaux; Acoustique [physics.class-ph]; Automatique / Robotique; Electromagnétisme; Milieux fluides et réactifs; Energie électrique; Polymères; Acoustique [physics.class-ph]; Biomécanique [physics.med-ph]; Matériaux et structures en mécanique [physics.class-ph]; Thermique [physics.class-ph]; Vibrations [physics.class-ph]; Physique mathématique [math-ph]; Physique Quantique [quant-ph]

David Desseauve, Laetitia Fradet, Robert Gherman, Yosra Cherni, Bertrand Gachon, et al.. Does the McRoberts’ manoeuvre need to start with thigh abduction? An innovative biomechanical study. BMC Pregnancy and Childbirth, 2020, 20 (1), pp.264. ⟨10.1186/s12884-020-02952-6⟩. ⟨hal-03622542⟩