Instruments and systems for an orthopedic shoulder replacement

1. An instrument assembly for a shoulder arthroplasty comprising:

a cut guide having a slot for aiding a resection of a head of a humerus; and

a positioning assembly configured to position the cut guide relative to the head of the humerus, wherein the positioning assembly is configured to couple to a reamer positioned in a medullary canal of the humerus, wherein the positioning assembly comprises:

a boom extending along a first axis and configured to position the cut guide relative to the reamer and the head of the humerus along the first axis, wherein the first axis is oriented at an acute angle to a longitudinal axis of the reamer;

an arm extending along a second curvilinear axis and coupled to the cut guide, wherein the arm is configured to be slidably moveable relative to the boom to position the cut guide relative to the head of the humerus about the reamer along the second curvilinear axis, wherein the arm has an arcuate longitudinal length configured to partially extend around the head of the humerus and is selectively positionally adjustable with respect to the reamer by between 0 degrees and 60 degrees of rotation, inclusive;

an arm holder configured to couple the arm to the boom, the arm holder configured to extend substantially parallel with the reamer when coupled to the boom and configured to be selectively positionally adjustable with respect to the boom; and

a boom holder coupling the boom to the reamer, wherein the boom holder is selectively positionally adjustable and securable with respect to the reamer to be moveable along an elongate length of the reamer.

2. The instrument assembly of claim 1 , wherein the arm holder includes a plurality of apertures that are spaced from one another, and wherein the plurality of apertures are each configured to provide a separate location for a fastener to connect the arm with the arm holder and thereby position the arm at a different relative orientation with respect to reamer and the humeral head.

3. The instrument assembly of claim 1 , wherein the arm is configured to be selectively positionally adjustable with respect to the arm holder, and wherein the arm holder is configured with a plurality of locations for connection with the arm.

4. The instrument assembly of claim 1 , wherein the cut guide has a curved shape along a surface interfacing the head of the humerus.

5. The instrument assembly of claim 1 , wherein the first axis is oriented at substantially 45 degrees to a longitudinal axis of the reamer.

6. A system comprising:

the instrument assembly for the shoulder arthroplasty of claim 1 ; and

a visualization instrument configured to size a glenoid, wherein the visualization instrument is configured to couple with a second reamer via a slot that extends outward from a central aperture configured to receive the second reamer.

7. The system of claim 6 , wherein the visualization instrument is selectively removable from the second reamer anywhere along a longitudinal length thereof via the slot.