Surgical throws — square vs granny
The one life-science paper that is actually about a knot we already cover.
Does not pick a knot
This page does not pick a knot for you. DNA, molecules, quantum braids and vortices stay off Decide.
Watch the mechanism
Square throw against granny throw
The essay's point is that alternating the throw direction is the lock. Hands show that in five seconds; prose takes a paragraph and still loses people.
- The alternating throw that seats flat, at the speed a surgeon actually ties itStanford Surgery · Opens on YouTube
How to Tie a Two-Handed Surgical Square Knot
External video from a creator we follow — not produced by us.
Loads only when you press play
What it means
Johanns et al. (Science Advances, 2023) show that square / reef throws lock and granny throws walk because of friction, geometry and plastic set — not because one has more crossings. Alternating throw direction is the lock. Same-direction throws are the granny. Granny is not among these knots; the reef knot is.
What it predicts
- ·Opposite-direction throws seat flat and lock.
- ·Same-direction throws walk under load.
- ·Suture security is a mechanical story, not a crossing-number story.
What it does not predict
- ·It does not give a Palomar a surgical rating.
- ·It does not say a reef knot is a bend for two dock lines.
- ·It does not transfer a suture-material number onto polyester or nylon rope.
Not for
- ·Fishing Decide
- ·Joining two working ropes as if reef were a sheet bend
- Johanns et al. — Strength of surgical knots (Sci. Adv., 2023) — Square vs granny is friction, geometry and plastic set — not crossing count.
- EPFL — Mechanics of the ideal surgical knot (2023) — Public summary of Johanns et al. Alternating throws lock; same-direction throws walk.
- Reef knot (Wikipedia) — Binding knot. Capsizes. Opposite-throw pair is the granny — not in these knots.