Patent ID: 8029571

Claim:
A containment system comprising: (a) a first implant structural member comprising: an outer surface; an inner surface defining a cavity; a lip comprising an inner edge defining a cavity opening, wherein the inner edge comprises: a first substantially arcuate portion having a first end and a second end, wherein the first substantially arcuate portion is defined as a portion of a first circle, a second substantially arcuate portion having a third end and a fourth end, wherein the second substantially arcuate portion is defined as a portion of a second circle that is concentric with the first circle and radially offset from the first circle, and a first connecting portion and a second connecting portion, wherein the first connecting portion connects the first end of the first substantially arcuate portion to the third end of the second substantially arcuate portion, the second connecting portion connects the second end of the first substantially arcuate portion to the fourth end of the second substantially arcuate portion, and neither the first connecting portion nor the second connecting portion extends along either the first circle or the second circle, and (b) an implant stem head, the implant stem head comprising: a generally spherical body having a surface configured to correspond to at least the first connecting portion enabling the implant stem head to be inserted into the first implant structural member when the implant stem head is in a first orientation; and a cavity; and (c) a separate femoral stem component which may be inserted into the cavity of the implant stem head, wherein the outer surface of the first implant structural member may be received by a shell, and wherein the implant stem head may be received by the first implant structural member, and wherein after the implant stem head is inserted into the cavity of the first implant structural member, rotated within the first implant structural member, and the femoral stem component inserted into the cavity of the implant stem head, the inner edge locks the implant stem head such that the implant stem head may articulate within the first implant structural member but cannot be removed from the first implant structural member.