Expandable bone plate assemblies

1. An expandable bone plate assembly comprising:

a top plate portion comprising a front side, a back side comprising a longitudinally extending blind slot, a transversely extending counterbore extending through the front and back sides of the top plate portion, and a bone screw hole extending through the front and back sides of the top plate portion;

a bottom plate portion comprising a front side, a back side, a transversely extending bore extending through the front and back sides of the bottom plate portion and a bone screw hole extending through the front and back sides of the bottom plate portion;

a pin comprising a pin head and a pin shaft depending from the pin head, the pin shaft disposed within the transversely extending bore of the bottom plate portion and having an outer diameter greater than the minor diameter of the transversely extending bore, the pin head disposed against the longitudinally extending blind slot of the top plate portion; and

a lock screw disposed within the transversely extending counterbore of the top plate portion.

2. The expandable bone plate assembly of claim 1 , wherein the transversely extending bore of the bottom plate portion is a counterbore and the pin head comprises a flange, the flange disposed against the longitudinally extending blind slot of the top plate portion.

3. The expandable bone plate assembly of claim 1 , wherein the bone screw hole of the top plate portion comprises at least two bone screw holes.

4. The expandable bone plate assembly of claim 1 , wherein the bone screw hole of the bottom plate portion comprises at least two bone screw holes.

5. The expandable bone plate assembly of claim 1 , wherein the longitudinally extending blind slot of the top plate portion comprises a left longitudinally extending blind slot and a right longitudinally extending blind slot.

6. The expandable bone plate assembly of claim 5 , wherein the transversely extending bore of the bottom plate portion comprises a left transversely extending bore and a right transversely extending bore.

7. The expandable bone plate assembly of claim 6 , wherein the pin comprises:

a left pin comprising a left pin head and a left pin shaft depending from the left pin head flange, the left pin shaft disposed within the bottom plate's left transversely extending bore and having an outer diameter greater than the minor diameter of the left transversely extending bore, the left pin head disposed against the left longitudinally extending blind slot of the top plate portion; and

a right pin comprising a right pin head and a right pin shaft depending from the right pin head, the right pin shaft disposed within the bottom plate's right transversely extending bore and having an outer diameter greater than the minor diameter of the right transversely extending bore, the right pin head disposed against the right longitudinally extending blind slot of the top plate portion.

8. The expandable bone plate assembly of claim 1 , wherein the front side of the bottom plate portion comprises a left and a right longitudinally extending tab that is disposed in a respective left and right longitudinally extending groove of the back side of the top plate portion.

9. The expandable bone plate assembly of claim 1 , further comprising a recess in fluid communication with the bone screw hole of the top plate portion; and

a rotatable bone screw lock mounted in the recess of the top plate portion and having a lock head including a laterally extending flange, wherein in a locked position, a part of the laterally extending flange is within the bone screw hole of the top plate portion.

10. The expandable bone plate assembly of claim 1 , wherein a recess is in fluid communication with the bone screw hole of the top plate portion, the recess defined by a retention portion of the front side of the top plate portion, a lower surface of the top plate portion, and a discontinuous wall comprising a gap in fluid communication with the bone screw hole of the top plate portion; and

a rotatable bone screw lock mounted in the recess of the top plate portion and having a lock head including a laterally extending flange having an outer edge that is below the front side of the top plate portion, wherein in a locked position, a part of the laterally extending flange is within the gap, and another part of the lock head is covered by the retention portion of the front side of the top plate portion.

11. The expandable bone plate assembly of claim 1 , further comprising a recess in fluid communication with the bone screw hole of the bottom plate portion; and

a rotatable bone screw lock mounted in the recess of the bottom plate portion and having a lock head including a laterally extending flange, wherein in a locked position, a part of the laterally extending flange is within the bone screw hole of the bottom plate portion.

12. The expandable bone plate assembly of claim 1 , wherein a recess is in fluid communication with the bone screw hole of the bottom plate portion, the recess defined by a retention portion of the front side of the bottom plate portion, a lower surface of the bottom plate portion, and a discontinuous wall comprising a gap in fluid communication with the bone screw hole of the bottom plate portion; and

a rotatable bone screw lock mounted in the recess of the bottom plate portion and having a lock head including a laterally extending flange having an outer edge that is below the front side of the bottom plate portion, wherein in a locked position, a part of the laterally extending flange is within the gap, and another part of the lock head is covered by the retention portion of the front side of the bottom plate portion.