Knee flexion and extension gap tensioning and measuring apparatus

1. A knee gap tensioning apparatus comprising:

a gap tensioner including:

a baseplate;

a top plate; and

a linkage positioned between and interconnecting the baseplate and the top plate and operable to move the top plate relative to the bottom plate between retracted and extended positions in response to application of an actuating force, wherein the linkage comprises links operable to move the top plate in an axial direction in response to lateral movement of the links in a direction perpendicular to the axial direction; and

wherein the top plate is pivotally connected to the linkage so as to be able to freely pivot about a single mechanical pivot axis to change its angular orientation relative to the base plate.

2. The apparatus of claim 1 wherein the linkage is operated by one or more cables coupled to the linkage.

3. The apparatus of claim 2 wherein at least one cable is routed at least partially inside the baseplate.

4. The apparatus of claim 2 wherein at least one cable passes over a cam surface defined by one of the links.

5. The apparatus of claim 1 wherein the linkage includes rollers mounted to the links and received in tracks of the baseplate.

6. The apparatus of claim 1 wherein the linkage includes sliders mounted to the links and slidably received in tracks of the baseplate.

7. The apparatus of claim 1 wherein the linkage is driven by a screw mechanism.

8. The apparatus of claim 1 further including a marking attachment which includes a body extending between first and second ends, wherein the first end is provided with means for attachment to the base plate of the gap tensioner, and the second end is provided with a marking implement.

9. The apparatus of claim 1 wherein the baseplate includes a gap tensioner coupler defining a first mechanical interface and being positioned at or near a distal end of the baseplate and is oriented so that it extends along and protrudes in an axial direction generally parallel to the pivot axis.

10. A knee gap tensioning apparatus comprising:

a gap tensioner including:

a baseplate;

a top plate; and

a linkage positioned between and interconnecting the baseplate and the top plate and operable to move the top plate relative to the bottom plate between retracted and extended positions in response to application of an actuating force,

wherein the top plate is pivotally connected to the linkage so as to be able to

freely pivot about a single mechanical pivot axis to change its angular orientation

relative to the base plate; and

an actuating instrument operable to apply the actuation force to the linkage, wherein:

the gap tensioner linkage has a first input-to-output displacement ratio, the actuating instrument has a second input-to-output displacement ratio, and the input-to-output displacement ratios of the gap tensioner and the actuating instrument are inverse to each other; and

wherein the actuating instrument is configured to apply the actuating force through a spring element thereof.

11. The apparatus of claim 10 wherein the actuating instrument has independent indicators of displacement and applied force of the linkage.

12. The apparatus of claim 10 wherein the actuating instrument is configured to indicate deflection of the spring element.

13. The apparatus of claim 10 wherein:

the gap tensioner includes a tensioner coupler having a first interface; and

the actuating instrument includes an actuating instrument coupler having a second interface complementary to the first interface.

14. A knee gap tensioning apparatus comprising:

a gap tensioner including:

a baseplate;

a top plate; and

a linkage positioned between and interconnecting the baseplate and the top plate and operable to move the top plate relative to the bottom plate between retracted and extended positions in response to application of an actuating force, wherein the top plate is pivotally connected to the linkage so as to be able to freely pivot about a single mechanical pivot axis to change its angular orientation relative to the base plate; and

an actuating instrument operable to apply the actuation force to the linkage, wherein:

the gap tensioner includes at least one sensor operable to measure a physical property of the gap tensioner and to generate a signal indicative of the property; and

the actuating instrument includes a transmitter operable to receive the signal and transmit the signal.

15. The apparatus of claim 14 further including a remote device operable to receive the signal and display an indication representative of the physical property.

16. The apparatus of claim 14 wherein the physical property is displacement, tension and/or tilt angle of the top plate.

17. The apparatus of claim 14 wherein the actuating instrument includes a powered actuator operable to apply the actuating force.

18. A knee gap tensioning apparatus comprising:

a gap tensioner including:

a baseplate;

a top plate; and

a linkage positioned between and interconnecting the baseplate and the top plate and operable to move the top plate relative to the bottom plate between retracted and extended positions in response to application of an actuating force, wherein the linkage comprises links operable to move the top plate in an axial direction in response to lateral movement of the links in a direction perpendicular to the axial direction;

wherein the top plate is pivotally connected to the linkage so as to be able to freely pivot about a single mechanical pivot axis to change its angular orientation relative to the baseplate;

an electronic receiving device;

two or more tracking markers positioned in range of the receiving device, at least one of its which is coupled to the gap tensioner; and

wherein the receiving device is operable in combination with the tracking markers to determine a position and orientation of each of the tracking markers relative to the electronic receiving device.

19. The apparatus of claim 18 wherein at least one of the tracking markers includes a C-shaped ankle clip.

20. The apparatus of claim 18 wherein at least one of the tracking markers is contained in the gap tensioner.

21. A combination of the apparatus of claim 18 and an actuating instrument coupled to the gap tensioner and operable to apply actuation force to the linkage.

22. The combination of claim 21 wherein at least one of the tracking markers is contained in the actuating instrument.

23. The combination of claim 21 wherein the actuating instrument includes a powered actuator operable to apply the actuating force.

24. The combination of claim 21 wherein:

the gap tensioner includes at least one sensor operable to measure a physical property of the gap tensioner and to generate a signal indicative of the property;

the actuating instrument includes a transmitter operable to receive the signal and transmit the signal; and

a remote device operable to receive the signal and display an indication representative of the physical property.