Support arm for medical device support system

1 . A support arm for a medical device support system, comprising:

a proximal hub and a distal hub;

an intermediate beam between the proximal hub and the distal hub, the intermediate beam having inward facing walls defining a cavity and including parallel ribs that project into the cavity defined by the inward facing walls; and,

at least one tension member extending through the cavity of the intermediate beam, the at least one tension member being secured at opposite ends to the proximal hub and the distal hub against relative pivotal movement between the intermediate beam and the proximal hub and against relative pivotal movement between the intermediate beam and the distal hub, wherein the at least one tension member is secured at opposite ends to the proximal hub and the distal hub to prevent axial movement of the at least one tension member relative to the proximal hub and the distal hub, the at least one tension member securing the proximal hub, the distal hub, and the intermediate beam together,

wherein the proximal hub includes a noncircular tubular end wall and the intermediate beam includes a noncircular tubular end wall, and the noncircular tubular end wall of the proximal hub is configured to mate with the noncircular tubular end wall of the intermediate beam at a mating interface without fasteners between the noncircular tubular end wall of the proximal hub and the noncircular tubular end wall of the intermediate beam such that torsional loading is transferred from the noncircular tubular end wall of the proximal hub to the noncircular tubular end wall of the intermediate beam and vice versa.

2 . The support arm of claim 1 , wherein the at least one tension member is in a state of tension and the intermediate beam is in a state of compression.

3 . The support arm of claim 1 , wherein the at least one tension member does not contact or engage the intermediate beam.

4 . The support arm of claim 1 , wherein the at least one tension member comprises four tension members.

5 . The support arm of claim 1 , wherein the at least one tension member comprises at least two tension members that have different lengths.

6 . The support arm of claim 1 , wherein the proximal hub includes at least one threaded hole and the at least one tension member is a threaded tension member that threads into the at least one threaded hole.

7 . The support arm of claim 1 , wherein the distal hub includes at least one clearance hole and the least one tension member passes through the at least one clearance hole such that an end of the at least one tension member is exposed.

8 . The support arm of claim 7 , wherein the at least one tension member is a threaded tension member, and further comprising a retainer that threads onto the exposed end and abuts a flat of the distal hub.

9 . The support arm of claim 1 , wherein the at least one tension member is selected from the group consisting of a threaded rod, a steel cable, and a plastic cable.

10 . The support arm of claim 1 , wherein the noncircular tubular end wall of the proximal hub corresponds in shape to the noncircular tubular end wall of the intermediate beam, wherein the noncircular tubular end wall of the proximal hub is configured to fit into the corresponding shape noncircular tubular end wall of the intermediate beam such that the noncircular tubular end wall of the proximal hub overlaps with the corresponding shape noncircular tubular end wall of the intermediate beam.

11 . The support arm of claim 10 , wherein the noncircular tubular end wall of the proximal hub has a shoulder and the shape corresponding noncircular tubular end wall of the intermediate beam has a stop face that abuts the shoulder.

12 . The support arm of claim 1 , wherein the proximal hub includes an end wall with a shoulder and the intermediate beam includes an end wall with a stop face that abuts the shoulder.

13 . The support arm of claim 1 , wherein the intermediate beam has a noncircular tubular shape in axial cross section.

14 . The support arm of claim 1 , wherein the proximal hub includes upper and lower plugs that fit into respective upper and lower receptacles of the intermediate beam.

15 . The support arm of claim 1 , wherein the intermediate beam is an extruded member.

16 . A method of assembling a support arm of a medical device support system, comprising:

providing a proximal hub having at least one elongated tension member fixed to the proximal hub with a free end extending away from the proximal hub;

providing an intermediate beam having inward facing walls defining a cavity and including parallel ribs that project into the cavity defined by the inward facing walls;

inserting the free end of the at least one elongated tension member into and through the cavity of the intermediate beam;

inserting the free end into a distal hub so that the intermediate beam is between the proximal hub and the distal hub; and,

tightening the free end to the distal hub so that the at least one tension member is in a state of tension and the intermediate beam is in a state of compression and such that the at least one tension member is secured at opposite ends to the proximal hub and the distal hub against relative pivotal movement between the intermediate beam and the proximal hub and against relative pivotal movement between the intermediate beam and the distal hub, and further such that the at least one tension member is secured at opposite ends to the proximal hub and the distal hub to prevent axial movement of the at least one tension member relative to the proximal hub and the distal hub, the at least one tension member securing the proximal hub, the distal hub, and the intermediate beam together,

wherein the proximal hub includes a noncircular tubular end wall and the intermediate beam includes a noncircular tubular end wall, and the noncircular tubular end wall of the proximal hub is configured to mate with the noncircular tubular end wall of the intermediate beam at a mating interface without fasteners between the noncircular tubular end wall of the proximal hub and the noncircular tubular end wall of the intermediate beam such that torsional loading is transferred from the noncircular tubular end wall of the proximal hub to the noncircular tubular end wall of the intermediate beam and vice versa.

17 . The method of claim 16 , wherein the free end of the at least one tension member is a threaded end and the tightening includes tightening a threaded nut onto the threaded end.

18 . The method of claim 16 , wherein the inserting the free end into the distal hub includes inserting the free end into a clearance hole inside the distal hub.

19 . A support arm for a medical device support system, comprising:

a proximal hub and a distal hub;

an intermediate beam between the proximal hub and the distal hub, the intermediate beam having inward facing walls defining a cavity and including parallel ribs that project into the cavity defined by the inward facing walls; and,

at least one tension member extending through the cavity of the intermediate beam, the at least one tension member being secured at opposite ends to the proximal hub and the distal hub against relative pivotal movement between the intermediate beam and the proximal hub and against relative pivotal movement between the intermediate beam and the distal hub, wherein the at least one tension member is secured at opposite ends to the proximal hub and the distal hub to prevent axial movement of the at least one tension member relative to the proximal hub and the distal hub, the at least one tension member securing the proximal hub, the distal hub, and the intermediate beam together,

wherein the proximal hub includes a noncircular tubular end wall and the intermediate beam includes a noncircular tubular end wall, and the noncircular tubular end wall of the proximal hub is configured to mate with the noncircular tubular end wall of the intermediate beam such that torsional loading is transferred from the noncircular tubular end wall of the proximal hub to the noncircular tubular end wall of the intermediate beam and vice versa, and

wherein the noncircular tubular end wall of the proximal hub and the noncircular tubular end wall of the intermediate beam each include a first arced portion having a first radius and a second arced portion having a second radius, wherein the first radius is different from second radius.

20 . The support arm of claim 19 , wherein the noncircular tubular end wall of the proximal hub and the noncircular tubular end wall of the intermediate beam each further include a third arced portion having a third radius that is different from the first radius and the second radius.