Patent ID: 11937850
Assignee: BIEDERMANN TECHNOLOGIES GMBH & CO. KG
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 15:
16. A bone anchoring device comprising:
a receiving part for coupling a rod to a bone anchoring element, the receiving part having a first end, a second end below the first end, and a central axis extending between the first end and the second end, the receiving part comprising:
two legs defining a recess at the first end for receiving the rod; and
a head receiving portion having an opening at the second end for inserting and pivotably holding a head of the bone anchoring element therein; and

a pressure member positionable at least partially in the head receiving portion for exerting pressure on the head of the bone anchoring element when the head is received in the head receiving portion, the pressure member comprising:
a first portion defining a rod support surface configured to extend into the recess for receiving the rod to contact the rod; and
a second portion having a radially inwardly facing surface defining a chamber for holding the head, the radially inwardly facing surface having a first radius of curvature configured to contact the head and an enlarged region that deviates radially outwardly from the first radius of curvature and that separates portions of the radially inwardly facing surface having the first radius of curvature into an upper region above the enlarged region and a lower region below the enlarged region, such that a wall thickness of the second portion at the enlarged region is reduced compared to a wall thickness of the second portion where the radially inwardly facing surface has the first radius of curvature.