This technique is used at times for Achilles tendon lengthening where severe tightness is noted.
The incision into the tendon is made in an upside down V shape, and as the lower portion is stretched out and then sutured together, the resulting shape more looks like an upside down letter Y.
The initial cut is outlined in a V shape (oriented sideways here).
The surface of the tendon is cut.
The tendon is lengthened a controlled amount.
The cut that previously had the shape of a V, when sutured together, has the shape of a Y.