Fig. 4

Deflection of a Burford retractor under loading (approximately 1000 N): a Retractor opened wide to illustrate the rack bending out of its initial unloaded plane (xy), with the center of the rack deflecting (d) toward the operator; b the distal ends of the arms (and so the distal edges of the blades) deflecting torsionally (about the z-axis, α); c the arms of the retractor deflecting torsionally (about the y-axis, β), causing the blades to come together, such that the distal edges of the blades are closer than the proximal edges