Stemless humeral components have the advantage of enabling the placement of the humeral articular surface in the desired location independent of the position of a stem in the medullary canal.
The technique I use is continuing to evolve with experience and from collaboration with my partners, our fellows, our residents, and my colleagues around the world. Below are some elements of my technique as of today. I hope to continue learning.
While this presentation reflects my current use of implants from a particular company, I have no financial or other conflicts of interest with this or any company.
The shoulder is approached through the deltopectoral interval and with a subscapularis peel, preserving the long head of the biceps (unless it is unstable or frayed).
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. This can be exposed with a 'baby' Hohmann retractor.
The inferior capsular reflection is revealed after the osteophytes have been removed. The plane of the cut 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).
The trial head size is estimated to match the anteroposterior dimensions of the neck cut. The trial head is positioned so that a few millimeters of the neck is exposed superiorly.
With the stemless, as with all humeral components, it is important that upper lateral aspect of the head does not extend superiorly to the berm
After the glenoid preparation for either a prosthetic component or a ream and run, the trial head is fit to and positioned on the neck cut and used as a guide for insertion of the guide pin
This pin is used to guide the humeral preparation
and for insertion of the trial blaze
so that the mobility and the stability of the head on the glenoid can be examined. With the trial in place I check for the following
(1) the mobilized subscapularis should reach the lesser tuberosity with the arm in at least 40 degrees of external rotation
(2) the range of motion should include 150 degrees of flexion and 60 degrees of internal rotation with the arm in 90 degrees of abduction
(3) the humeral head should be translatable posteriorly by 50 percent of the width of the glenoid and return to the centered position when the translating force is removed
(4) when the arm is held in 90 degrees of flexion, the humeral head should translate no more than 50 percent of the width of the glenoid
One of the biggest challenges is make sure that the reconstruction does not tighten the shoulder by over lateralizing the proximal humerus in relation to the scapula; this is important for both the anatomic total shoulder
and for the ream and run.
If the shoulder is tight preoperatively, it is important to perform a complete capsular release around the humerus and glenoid
as well as a 360 degree release of the subscapularis.
Avoiding overtightening also requires the surgeon to be mindful of the effect of humeral head geometry on the volume of the head component, recognizing that the choices of head diameter of curvature and head thickness are limited by the inventory in each company's system.
I’m always prepared to convert to a short humeral stem for one of several indications:
(1) The bone of the proximal humerus is too soft to securely fix the nucleus. Rather than relying on the "thumb test" or on a preoperative CT to estimate the local bone density, it seems more practical to insert the blaze trial
to see if it fits securely in the bone.
If not, I convert to a short stem positioned to place the head in the previously defined anatomic position.
(2) The fins of the nucleus are too long for the humerus.
This is most likely to be an issue in small individuals with soft bone (which leads to consideration of a larger sized nucleus with longer fins). The risk of “too long fins) can be estimated by holding the trial blaze up to the humeral neck (the “eye-ball test”)
If this is a concern, I convert to a short stem positioned to place the head in the previously defined anatomic position.
(3) Intraoperative testing reveals that an anatomically positioned humeral head cannot be stabilized on the glenoid without overstuffing the joint. In this situation I convert to a short stem to support the use of an anteriorly eccentric humeral component
An important element of avoiding stiffness is having a repair of the subscapularis peel that is sufficiently robust that gentle mobilization of the shoulder can be instituted soon after surgery with minimal risk of subscapularis failure. I use 6 sutures of Fiberwire passed through solid bone at the lesser tuberosity.
An additional one or two Fiberwires are placed in the rotator interval capsule to reinforce the subscapularis repair. As shown below, these sutures are passed over the long head tendon of the biceps, which is preserved in almost all cases.
At the conclusion of the case I verify that the shoulder has stability and a full range of assisted flexion, documented with a “parting shot” photograph that is included in the operative note.
This is what I’m doing at the start of 2025. I would welcome comments and suggestions on alternative approaches.
Once again thanks to our residents Jon Yamaguchi and Kevin Khoo for their help with the figures shown here,
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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).
