Intramedullary nail with coupled shafts
View Patent ↗A nail assembly for use in trauma surgery is provided. The nail assembly includes an intramedullary shaft including a first transverse passage and a second transverse passage in the shaft. The first transverse passage and the second transverse passage do not contact each other on the shaft. The nail assembly also includes a first shaft extending through the first transverse passage in the intramedullary shaft and a second shaft extending through the second transverse passage in the intramedullary shaft. The second shaft includes an engagement feature configured to bring the second shaft into contact with the first shaft. The engagement feature may be in the form of a lateral mechanical feature that provides simultaneous unilateral coupled motion of the first shaft with the second shaft through the transverse passages in the intramedullary shaft.
1. An intramedullary nail assembly, comprising:
an intramedullary shaft including (i) a lateral sidewall portion having a first lateral orifice structure that defines a first lateral opening and a second lateral orifice structure that defines a second lateral opening, and (ii) a medial sidewall portion having a first medial orifice structure that defines a first medial opening and a second medial orifice structure that defines a second medial opening;
a first shaft extending through said first lateral opening and said first medial opening and spaced apart from said second lateral opening and said second medial opening, said first shaft having (i) a first head portion possessing a first engagement feature, and (ii) a first stem portion defining a first shaft axis; and
a second shaft extending through said second lateral opening and said second medial opening and spaced apart from said first lateral opening and said first medial opening, said second shaft having (i) a second head portion possessing a second engagement feature, and (ii) a second stem portion defining a second shaft axis that is substantially parallel to said first axis,
wherein said first engagement feature contacts said second engagement feature so as to inhibit axial movement of said first shaft with respect to said second shaft, and
wherein said first stem portion is spaced apart from said second stem portion,
wherein said first engagement feature includes a first set of external threads,
wherein said second engagement feature includes a second set of external threads, and
wherein said first set of external threads are meshingly engaged with said second set of external threads.
2. The intramedullary nail assembly of claim 1 , wherein:
said first set of external threads extends only partially around a circumference of said first shaft, and
said second set of external threads extends completely around a circumference of said second shaft.
3. The intramedullary nail assembly of claim 2 , wherein:
said first shaft includes a first longitudinally extending blocking structure and a second longitudinally extending blocking structure,
said first longitudinally extending blocking structure and said second longitudinally extending blocking structure define a space therebetween,
said first set of external threads is positioned in said space.
4. The intramedullary nail assembly of claim 3 , wherein said second set of external threads is also positioned in said space when said first engagement feature is positioned in contact with said second engagement feature.
5. The intramedullary nail assembly of claim 1 , further comprising an externally threaded set screw having a contact end portion, wherein:
said intramedullary shaft includes an internally threaded portion that defines a central passageway configured to receive said externally threaded set screw,
said first shaft includes a first longitudinally extending groove defined in a first exterior surface thereof, and
said contact end portion of said externally threaded set screw is configured to be received into said first longitudinally extending groove so as to inhibit rotational movement of said first shaft with respect to said intramedullary shaft.
6. The intramedullary nail assembly of claim 5 , wherein:
said second shaft includes a second longitudinally extending groove defined in a second exterior surface thereof, and
said contact end portion of said externally threaded set screw is configured to be received into said second longitudinally extending groove so as to inhibit rotational movement of said second shaft with respect to said intramedullary shaft.
7. The intramedullary nail assembly of claim 1 , wherein said first lateral orifice structure and said second lateral orifice structure are spaced apart from each other.
8. The intramedullary nail assembly of claim 7 , wherein said lateral sidewall portion includes a lateral wall segment that is interposed between said first lateral orifice structure and said second lateral orifice structure.
9. The intramedullary nail assembly of claim 7 , wherein said first medial orifice structure and said second medial orifice structure are spaced apart from each other.
10. The intramedullary nail assembly of claim 8 , wherein:
said first medial orifice structure and said second medial orifice structure are spaced apart from each other,
said lateral sidewall portion includes a lateral wall segment that is interposed between said first lateral orifice structure and said second lateral orifice structure, and
said medial sidewall portion includes a medial wall segment that is interposed between said first medial orifice structure and said second medial orifice structure.
11. The intramedullary nail assembly of claim 1 , wherein:
said first stem portion includes a first externally threaded distal portion configured to be received in bone,
said second stem portion includes a second externally threaded distal portion configured to be received in bone, and
said first externally threaded distal portion is spaced apart from said second externally threaded distal portion.
12. The intramedullary nail assembly of claim 1 , wherein:
said first shaft is an anti-rotation screw, and
said second shaft is a lag screw.
13. The intramedullary nail assembly of claim 12 , wherein said intramedullary shaft is an intramedullary nail.