Ugaritic

ḳmṣ - to curl up, to bend (DUL 703)

For the comparison cf. Kogan 2015:336, with fn. 989.

PS
*ḳ(ʷ)Vyṣ-, *k(ʷ)Vṣṣ- - joint, point of connection between bones (SED I No. 172 )

Attested in South-Semitic area only. Meanings in Arb., Gez. and Soq. rather diverse; S. Eth. forms may be of a different origin. 

Ugr. ḳmṣ also likely belongs to this root (Kogan 2015:336, with fn. 989).