[Plane]

B379 Hurting Yourself says "Apply this damage to the body part you used to attack" and that "Your own DR protects against this damage."

I think this applies to worn DR and not just natural DR (ie how boxing gloves give DR against hurting yourself with punches).

Initially I would assume this to be "Leg" but GURPS Low-Tech forces me to think about this more critically.

LT100's "Armor Locations Table" allows pieces to be worn separately, with a % used to determine "Cost and Weight".

The 100% of Legs is broken down into 50% Shins 45% Thighs 5% Knees, and using random determination 1-3 is a shin, 4 is a knee, 5-6 is a thigh.

In cases where legs are only partially armored (perhaps someone is poor and can only afford to cover certain parts, or for other reasons) it would then be important to know what different ways you could deliver a "Knee Strike" to benefit from DR.

Even for low-damage (less than 5) or to soft targets (lacks hard DR of 3+) this would be important for hitting someone with Spines or Aura.

I know I've seen some moves called as 'knees' even though the knee itself doesn't make contact, like a 'knee to the groin' at super close contact (pelvises are closer than femur length away) is actually just jamming the top of the knee into the groin, and a 'running knee' might actually involve the knee clearing above the target and the shins hitting instead.

In either case it's probably safer since damage to that body part wouldn't have the 'Joints' threshold like I assume knees would.

If it was the shin then should this "Shin Strike" variant follow the same rules as a 'Shin Kick' does on MA112/124.

Shins/Knees are bony and thighs aren't (plus have less leverage) so if a "Thigh Strike" was an allowable option of the "Knee Strike" technique, should it be -1 to damage?