Shoulder arthroplasty - consideration of varus and valgus head position

Total Shoulder Arthroplasty Outcome for Treatment of Osteoarthritis: A Multicenter Study Using a Contemporary Implant.

These authors present their results of primary total shoulder arthroplasty for osteoarthritis using an implant that provides dual eccentricity and variable neck and version angles for reconstruction of proximal humeral anatomy using a replicator plate interposed between the head and stem.

This design enabled the surgeon to vary the angle of the head on the stem by 15 degrees.

At a mean follow-up of 3 years (minimum, 2 years), they had an 81% follow-up rate of 218 total shoulders. Range of motion and clinical outcomes were significantly improved at final follow-up. 

There were 32 complications in 25 shoulders. Seven shoulders had multiple complications. The most common postoperative complication was rotator cuff failure (13 shoulders, including 8 treated with revision arthroplasty). The second most common complication was infection (6 shoulders, 1 with a superficial suture abscess and 5 with deep infections). Other complications were instability (4, with 2 caused by rotator cuff insufficiency), glenoid loosening (4, with 2 caused by infection), stiffness (3), nerve issue (1), and hematoma evacuation (1).

In 21 shoulders, these complications were treated with revision shoulder arthroplasty (16 shoulders), arthroscopic capsular release (3), evacuation of postoperative hematoma (1), and débridement of suture abscess (1). The 16 revision shoulder arthroplasties performed were conversion to reverse shoulder arthroplasty (11 shoulders) and placement of an antibiotic spacer for infection (5).

Comment: There is substantial variability in the anatomy of the arthritic humerus; the 'anatomic' location of the previously normal articular surface is difficult to determine.

While a number of implant systems allow variability in the inclination of the head, the effect on the center of rotation of the articular surface seems small.

We use a simpler approach of placing the humeral head at an angle of 45 degrees with the medullary axis of the shaft in all cases, irrespective of the appearance of the preoperative pathoanatomy.

  

"normal"

"varus"

"valgus"

                                  

                           

 

The only variability in head position that we've found useful is anterior or posterior eccentricity to optimize  intraoperative stability (see this link).

               

 

The use of the eccentric humeral head does not require an interposed replicator plate.

Be sure to visit "Ream and Run - the state of the art"  regarding this radically conservative approach to shoulder arthritis at this link.

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