Minimally invasive spinal fixation system and related methods
This application describes surgical instruments and implants for building a posterior fixation construct across one or more segments of the spinal column. Extension guides are provided that attach to bone anchors implanted within the spine. The extension guides have a guide channel that align with a rod channel in the anchor to help direct the rod to the anchor. Instruments are provided to aid in insertion and positioning or the rod.
1 . A spinal fixation anchor, comprising:
an implantable portion including a rod housing having a first arm separated from a second arm by a rod channel; and
an extension guide removably coupled to the rod housing, the extension guide including:
a first extension arm and a second extension arm each having a distal end and a proximal end, the distal end of the first extension arm being coupled to the first arm of the rod housing by a first breakable joint, and the distal end of the second extension arm being coupled to the second arm of the rod housing by a second breakable joint,
wherein the first breakable joint comprises a first surface groove positioned between the first arm and the first extension arm, and the second breakable joint comprises a second surface groove positioned between the second arm and the second extension arm, and
wherein the proximal end of the first extension arm is removably coupled to the proximal end of the second extension arm by a pair of joint portions extending therebetween, wherein each of the pair of joint portions includes a first sidewall, a second sidewall opposite the first sidewall, and a breakable joint positioned between the first and second sidewalls,
wherein each of the pair of joint portions include opposed vertical surface grooves to reduce material thickness along each of the pair of joint portions;
a guide cap configured to releasably couple to a respective proximal end of each of the first and second extension arms, the guide cap having a circular recess configured to surround the proximal ends of the first and second extension arms, and a pair of projections extending radially inwardly from an inner wall of the circular recess and adapted to be received in respective slots of the first and second extension arms.
2 . The spinal fixation anchor of claim 1 , wherein the extension guide further includes a guide channel extending between the distal ends and the proximal ends of the first and second extension arm.
3 . The spinal fixation anchor of claim 2 , wherein the opposed vertical surface grooves project inwardly toward a portion of the guide channel.
4 . The spinal fixation anchor of claim 2 , wherein the guide channel is aligned with the rod channel.
5 . The spinal fixation anchor of claim 2 , wherein the guide channel includes a first width dimensioned to accommodate a rod therein, and wherein each of the pair of joint portions has a second width that is less than the first width of the guide channel.
6 . The spinal fixation anchor of claim 1 , wherein the distal end of each of the first and second extension arms includes a guide and advancement feature that engages with a guide and advancement feature of the rod housing.
7 . The spinal fixation anchor of claim 1 , wherein the rod housing includes a guide and advancement feature adapted to engage with a complementary guide and advancement feature on a locking cap configured to lock a rod within the rod housing.
8 . The spinal fixation anchor of claim 1 , wherein the guide cap is configured to releasably couple to the respective proximal end of each of the first and second extension arms after the breakable joint is broken.
9 . The spinal fixation anchor of claim 1 , wherein the guide cap is configured to restrict the first and second extension arms from flexing apart.
10 . The spinal fixation anchor of claim 1 , wherein the implantable portion further includes a bone anchor coupled to the rod housing.
11 . A system comprising:
a spinal fixation anchor including:
an implantable portion including a rod housing having a first arm separated from a second arm by a rod channel, and
an extension guide removably coupled to the rod housing, the extension guide including:
a first extension arm and a second extension arm each having a distal end and a proximal end, the distal end of the first extension arm being coupled to the first arm of the rod housing by a first breakable joint, and the distal end of the second extension arm being coupled to the second arm of the rod housing by a second breakable joint,
wherein the first breakable joint comprises a first surface groove positioned between the first arm and the first extension arm, and the second breakable joint comprises a second surface groove positioned between the second arm and the second extension arm, and
wherein the proximal end of the first extension arm is removably coupled to the proximal end of the second extension arm by a pair of joint portions extending therebetween, wherein each of the pair of joint portions includes a first sidewall, a second sidewall opposite the first sidewall, and a breakable joint positioned between the first and second sidewalls,
wherein each of the pair of joint portions include opposed vertical surface grooves to reduce material thickness along each of the pair of joint portions;
a guide cap configured to releasably couple to a respective proximal end of each of the first and second extension arms, the guide cap having a circular recess configured to surround the proximal ends of the first and second extension arms, and a pair of projections extending radially inwardly from an inner wall of the circular recess and adapted to be received in respective slots of the first and second extension arms; and
a breaking tool adapted to sever a connection between one of the first and second extension arms and a corresponding one of the first and second arms of the rod housing.
12 . The system of claim 11 , wherein the extension guide further comprises a guide channel aligned with the rod channel.
13 . The system of claim 12 , wherein the opposed vertical surface grooves project inwardly toward a portion of the guide channel.
14 . The system of claim 11 , wherein the breaking tool is further adapted to sever a connection between the first and second extension arms.
15 . The system of claim 11 , wherein the breaking tool is further adapted to break the breakable joint of each of the pair of joint portions.
16 . The system of claim 11 , wherein the breaking tool includes a cam that is receivable within the extension guide.
17 . The system of claim 16 , wherein the breaking tool further includes a handle and a drive shaft configured to rotate and having a proximal end coupled to the handle and a distal end coupled to the cam.