Constrained acetabular insert for total hip arthroplasty

摘要

A hip prosthesis (20) having a shell (22), liner (24), and retainer ring (26) is utilized for hip arthroplasty. The liner (24) fits inside the shell (22), which is attached to a patient's pelvis, and the retainer ring (26) engages a terminal liner margin (54) to inhibit expansion of and decrease the size of a restricted liner opening (72) defined by the liner margin (54). By inhibiting expansion of the liner opening (72), the ball (92) of a patient's femur (90) is securely held in the liner (24). In one embodiment, the liner (98) is inhibited from rotation relative to the shell (96) by a plurality of protrusions (106) which mate with recesses (102) in the shell (96). In that embodiment, the liner (98) is provided with catch lips (108) to hold the liner (98) in the shell (96) and a positioning flange (110) which operates to form a relief gap (120) between the shell (96) and the liner (98). In another embodiment, the retainer ring comprises an attachment portion (128) and a retainer portion (130) with a threaded connection (132) between the attachment portion (128) and the retainer portion (130).