Stemless humeral arthroplasty - the head cut

Here are some thoughts about the head cut for stemless humeral arthroplasty (for either ream and run or anatomic total shoulder). Credit to Jon Yamaguchi and Kevin Khoo, UW residents par excellence, for their collaboration and work on the figures shown here.

With a bit of experience, the humeral component can be positioned optimally, without concern about the influence of a stem (short or standard length). The humeral component positioning is not dependent on CT scans or 3D preoperative planning. Instead I like to emphasize the importance of handcraft.

The head cut is the key: 135 degrees with the long axis of the shaft, 30 degrees of retroversion, resecting the maximal amount of neck while protecting the cuff and long head of biceps superiorly and the cuff posteriorly. 

Excellent exposure is essential. The anterior and inferior osteophytes are vigorously resected. The "Hinge point" is the superior margin of the humeral articular surface, identified just inside the long head tendon of the biceps (which is preserved) and the supraspinatus. The capsular reflection is revealed after the osteophytes have been removed. The plane of the cuff is shown as the yellow line connecting the hinge point and the inferior capsular reflection; it is oriented at an angle of 135 degrees with the humeral shaft.  The surgeon must stand tall so that she or he has the "Birds Eye View" of the posterior rotator cuff to assure that the saw passes just anterior to the infraspinatus insertion.

Here are examples of what to avoid:

(1)  underresected humeral necks resulting in overstuffing of the joint (see how to overstuff an anatomic arthroplasty). 

and 

(2) poorly oriented head cuts

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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link)
Shoulder rehabilitation exercises (see this link).