Transverse link having spherical ball joint
View Patent ↗A transverse link with a pair of opposing engagement members having a spherical ball bearing configured to fix a respective screw extender with respect to each other is provided. The spherical bearing is configured to allow the engagement member to rotate in three dimension so as to accommodate the position of a pair of respective screw extenders. The transverse link includes an automatic latching mechanism configured to fixed the spatial distance between the ends of the rod fixation instruments with respect to each other.
1. An engagement member for use in a transverse link, the transverse link having a base and an axial displacement mechanism, the engagement member comprising:
a stem having a spherical ball bearing disposed on a distal end of the stem, a proximal end of the stem capable of being disposed within the base of the transverse link, the axial displacement mechanism capable of being operatively attached to the stem so as to move the stem along an axis in and out of the base, the spherical ball bearing having a bore, and a pair of chamfered edges disposed on opposite ends of the bore, the chamfered edges extending radially about an axis of the bore;
a receiving portion rotatably mounted to the spherical ball bearing, the receiving portion having a pair of spaced apart bearing supports configured to engage opposing surfaces of the spherical ball bearing so as to rotatably hold the spherical ball bearing therebetween; and
a tightening member operatively connected to the bearing supports so as to lock the spherical ball bearing in a fixed relationship with the bearing supports, the tightening member having a shaft disposed within the bore, a rotational movement of the spherical bearing limited by abutment of the shaft against respective chamfered edges of the spherical ball bearing.
2. The engagement member as set forth in claim 1 , wherein the tightening member is a knob, the shaft extending from the knob.
3. The engagement member as set forth in claim 2 , wherein each of the pair of bearing supports includes an aperture, each of the apertures is axially aligned with the other, and one of the apertures is threaded.
4. The engagement member as set forth in claim 2 , wherein at least one of the chamfered edges is angled between 15 to 65 degrees with respect to an axis of the shaft.
5. The engagement member as set forth in claim 1 , wherein the stem includes a plurality of teeth.
6. The engagement member as set forth in claim 1 , wherein the receiving portion is generally ring shaped.
7. The engagement member as set forth in claim 2 , wherein the knob includes a plurality of indents.
8. The engagement member as set forth in claim 1 , wherein the stem is narrowed adjacent the spherical ball bearing.
9. A transverse link for securing two opposing rod fixation instruments together in a fixed position while simultaneously allowing working ends of the rod fixation instruments to pivot in three dimensional space, the transverse link comprising:
a base having an elongated bore and a housing disposed on one end of the base, the elongated bore defining a pair of open ends,
a pair of engagement members, each of the pair of engagement members having:
a spherical ball bearing and a stem fixedly mounted to the spherical ball bearing, the spherical ball bearing having a bore and a pair of chamfered edges disposed on opposite ends of the bore, the chamfered edges extending radially about an axis of the bore;
a receiving portion rotatably mounted to the spherical ball bearing, the receiving portion having a pair of spaced apart bearing supports configured to engage opposing surfaces of the spherical ball bearing so as to rotatably hold the spherical ball bearing therebetween; and
a tightening member operatively connected to the bearing supports so as to lock the spherical ball bearing in a fixed relationship with the bearing supports, the tightening member having a shaft disposed within the bore, a rotational movement of the spherical bearing limited by the abutment of the shaft against respective chamfered edges of the spherical ball bearing;
wherein one of the stems is fixed to one end of the base and the other stem is slidably disposed within the housing; and
an automatic latching mechanism mechanically coupled to the housing, the automatic latching mechanism configured to automatically fix at least one of the stems within the housing.
10. The transverse link as set forth in claim 9 , wherein the automatic latching mechanism includes a blocking member having a pass-through slot configured to engage at least one of the stems, the blocking member disposed within a central opening of the housing, and a biasing member configured to urge the blocking member into engagement with at least one of the stems so as to fix at least one of the stems in position with respect to the housing.
11. The transverse link as set forth in claim 10 , wherein at least one of the stems includes a plurality of teeth and a bottom wall surface of the pass-through slot includes a plurality of raised edges forming a surface complimentary to the teeth.
12. The transverse link as set forth in claim 10 , wherein the blocking member includes a cylindrical block projecting beyond an outer surface of the blocking member, and a top surface of the housing is a saddle configured to prevent the cylindrical block from advancing.
13. The transverse link as set forth in claim 10 , wherein one of the pair of stems is shorter than the other.
14. The transverse link as set forth in claim 9 , wherein for at least one of the engagement members, the tightening member is a knob, the shaft extending from the knob.
15. The transverse link as set forth in claim 14 , wherein, for at least one of the engagement members, each of the pair of bearing supports includes an aperture, each of the apertures is axially aligned with the other, and one of the apertures is threaded.
16. The transverse link as set forth in claim 14 , wherein, for at least one of the engagement members, at least one of the chamfered edges is angled between 15 to 65 degrees with respect to an axis of the shaft.
17. The transverse link as set forth in claim 9 , wherein at least one of the receiving portions is generally ring shaped.
18. The transverse link as set forth in claim 14 , wherein the knob includes a plurality of indents.
19. The transverse link as set forth in claim 9 , wherein, for at least one of the engagement members, the stem is narrowed adjacent the spherical ball bearing.
20. The transverse link as set forth in claim 9 , wherein the base has a rectangular prism shape.