These authors sought to evaluate the ability of a posteriorly stepped augmented glenoid component, used in 71 patients (mean 65 years of age) with primary glenohumeral osteoarthritis with B2 or B3 glenoid morphology, to correct preoperative retroversion and humeral head subluxation and to identify factors associated with radiographic radiolucency and patient-reported clinical outcomes.
At a median of 2.4 years (range, 1.9 to 5.7 years); the Penn Shoulder Score, range of motion, humeral head centering, and glenoid version were significantly improved. Patients with persistent posterior subluxation of the humeral head postoperatively had worse preoperative fatty infiltration of the teres minor and greater postoperative component retroversion. Patients with center-peg osteolysis had more preoperative joint-line medialization and posterior glenoid bone loss. Patients with more preoperative humeral head posterior subluxation had a lower PSS.
Postoperative humeral head centering on the glenoid component was measured as the anteroposterior humeral head glenoid alignment (HGA-AP) on an axillary radiograph as the amount of posterior displacement of the head center (black dot) with respect to the glenoid component centerline (solid green line) divided by the radius of curvature of the humeral head. In the example below the humeral head component is centered on the glenoid component centerline.
In the example below the humeral head center lies posterior to the glenoid component centerline
Comment: It was of interest to compare these results with those of another recent paper,
Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty?
This study analyzed 71 patients having total shoulder arthroplasty with a conventional non-augmented glenoid component inserted with no specific effort to change the version of the glenoid.
Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty?
This study analyzed 71 patients having total shoulder arthroplasty with a conventional non-augmented glenoid component inserted with no specific effort to change the version of the glenoid.
The authors compared the 21 shoulders in which the glenoid component was implanted in 15° or greater retroversion (mean ± SD, 20.7° ± 5.3°) with the 50 in which it was implanted in less than 15° retroversion (mean ± SD, 5.7° ± 6.9°). At the 2-year followup the mean (± SD) improvement in the SST (6.7 ± 3.6; from 2.6 ± 2.6 to 9.3 ± 2.9) for the retroverted group was not inferior to that for the nonretroverted group (5.8 ± 3.6; from 3.7 ± 2.5 to 9.4 ± 3.0). The percent of maximal possible improvement (%MPI) for the retroverted glenoids (70% ± 31%) was not inferior to that for the nonretroverted glenoids (67% ± 44%).
No patient in either group reported symptoms of subluxation or dislocation. The radiographic results for the retroverted glenoid group were similar to those for the nonretroverted group with respect to central peg lucency (four of 21 [19%] versus six of 50 [12%]; p = 0.436. The mean percentages of posterior humeral head decentering were also similar (3.4% ± 5.5% versus 1.6% ± 6.0%; p = 0.223). The percentage of patients with retroverted glenoids undergoing revision (0 of 21 [0%]) was not inferior to the percentage of those with nonretroverted glenoids (three of 50; [6%]; p = 0.251).
The postoperative decentering was measured on an axillary view in essentially the same manner as in the other paper, except that the displacement is express as a percent of the head diameter rather than the radius. In the example below the humeral head is centered on the glenoid.
The following table attempts to compare the shoulders from each article with respect to postoperative glenoid component retroversion of less than 15 degrees and postoperative glenoid version of 15 degrees or more.
In both series the results appear similar for glenoid components inserted in more or less than 15 degrees of retroversion. There were no revisions for glenoid failure in either series.
It is recognized that long term studies will be needed to determine the relative effectiveness and longevity of different approaches to the retroverted glenoid.
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