Methods for connecting a longitudinal member to a bone portion

A polyaxial fixation assembly, comprising:

• a shank having a head formed on a proximal end of the shank, the head having a distal portion connected to the proximal end of the shank, a proximal surface having a recess, and a spherical surface with a radially extending shoulder extending around a periphery of the head between the proximal surface of the head and the distal portion of the head, wherein the shoulder is disposed closer to the proximal surface of the head than the proximal end of the shank, along a longitudinal axis of the shank;
• a housing having a first, proximal opening adapted to receive a spinal fixation rod, a second, distal opening having a diameter sized to permit passage of the shank therethrough while maintaining the head therein, and a longitudinal axis extending between the proximal and distal openings, the housing further including a spherical seat adjacent the second, distal opening to polyaxially seat the spherical surface of the head;
• a spacer configured for being disposed with the housing, the spacer having a channel in a proximal surface of the spacer configured for receiving the spinal fixation rod, and a distal surface configured to engage the head, the spacer having a circumferential groove disposed in an outer wall thereof, the entire groove positioned below a bottom-most portion of the channel;
• and
• a compressible member configured to be disposed within the housing and within the groove in the spacer, the compressible member adapted to exert a force on an inner wall of the housing that generates a frictional force exerted on the head, thereby enabling the shank to be maintained in a desired angular orientation with respect to the housing in the absence of the spinal fixation rod, wherein the angular orientation of the shank with respect to the housing may be changed by manually moving the housing relative to the shank.

A method of producing an apparatus for retaining bone portions in a desired spatial relationship, comprising:

• inserting a fastener, a compressible member, and a spacer through an opening in a housing, the fastener having a shank engageable with a bone portion and a head formed on a proximal end of the shank, the head including a spherical surface with a radially extending shoulder extending around a periphery of the head spaced from a proximal surface of the head proximal of the spherical surface, wherein the shoulder is disposed closer to the proximal surface of the head than the proximal end of the shank, along a longitudinal axis of the shank, the housing having a passage formed along a longitudinal axis of the housing and a seat adapted to polyaxially seat the head of the fastener, the spacer having a channel in a proximal surface of the spacer adapted to receive a spinal fixation rod, and a circumferential groove in an outer wall thereof, the entire groove positioned below a bottom-most portion of the channel, the compressible member adapted to provide a translating force against an inner surface of the housing to enable the shank to be maintained in a desired angular orientation relative to the housing in the absence of the spinal fixation rod and before locking the head within the housing;
• and
• positioning the spacer and the compressible member in the passage of the housing such that the compressible member is disposed within the groove and the spacer contacts the head and the housing, the translating force generated by the compressible member creating a frictional engagement between the housing and the head of the fastener that holds the position of the housing relative to the fastener when the spinal fixation rod is not secured in the housing.