Total shoulder arthroplasty: the success of a basic approach with a standard all-polyethylene glenoid

Medium-Term Clinical and Radiographic Results of an All-Polyethylene, Pegged, Bone-Ingrowth Glenoid Component

These authors previously reported the successful 4-year outcomes of anatomic total shoulder replacement using an allpolyethylene, pegged, hybrid-fixation (bone ingrowth and cement) glenoid component (see this link). At a mean duration of follow-up of 46.7 months (range, 24 to 99 months) the  median American Shoulder and Elbow Surgeons (ASES) score was 97. Seventy-eight of 83 shoulders (94%) demonstrated a perfect Lazarus score for radiolucency (0, indicating no radiolucency). Sixty-eight (82%) shoulders demonstrated complete osseointegration, with bone ingrowth between all of the flanges seen on coronal CT; 5 (6) demonstrated partial osseointegration; and 10 (12%) demonstrated osteolysis around the central peg. Most radiolucent lines were in the inferior Yian zones. There were no correlations between the Yian CT scores and either the ASES or Oxford score.

Here are the Yian Zones

Here is an example of complete central peg osseointegration

In the present study, they report on that patient cohort after another 4 years of follow-up (mean, 101 months; range, 77 to 146 months). At that time, the median ASES score was 92 points. Osseointegration, demonstrated by bone ingrowth between the flanges on the central peg as seen on coronal computed tomography (CT), was complete in 75% of the shoulders, partial in 21%, and absent in 4%. The median Yian score was 1, with only 1 shoulder prosthesis defined as definitely loose (Yian score, 18) and 1 as possibly loose (Yian score, 8). Radiolucencies were most common around the  3 cemented peripheral pegs. When the results at the 8-year follow-up were compared with those at 4 years, the increased prevalence of radiolucent lines did not reach significance. At the 8-year follow-up, the Yian score had increased in 13 shoulders (compared with the score at 4 years), remained stable in 39, and was lower in 1.

Here's a summary table:

Two shoulders underwent revision between the 4 and 8-year follow-up points. The first was revised 88 months after implantation, due to rotator cuff failure and glenoid loosening. The glenoid component demonstrated radiolucency around all 4 pegs on radiographs and was grossly loose at revision surgery. The second shoulder was revised 53 months after implantation, following a fall and massive cuff tear resulting in pseudoparalysis. On radiographs, the glenoid component demonstrated no radiolucent lines and there was osseointegration between the central flanges. The glenoid component was well-fixed at the time of revision surgery. No other late complications or reoperations were recorded. Four shoulders were revised prior to the 4-year follow-up period: 1 revision was due to aseptic loosening; the others were due to rotator cuff failure, glenoid fracture, and Propionibacterium acnes infection. 

The overall all-cause revision rate for this cohort was 5% (6 of 118).

Comment: This median 8 year followup with a basic glenoid component is most encouraging. The CT analyses indicate a very low prevalence of radiolucencies behind the glenoid component, with only 13 shoulders given a Yian score of >1. The areas demonstrating most radiolucencies corresponded to the 3 cemented peripheral pegs, and more particularly to the inferior 2 pegs. This suggests that loosening occurs through eccentric loading causing the peripheral pegs to “rock” loose. It is reassuring that this radiolucency does not appear to affect the central peg, and that the osseointegration seen between the flanges is maintained over time. With a 96% prevalence of partial or complete osseointegration between the flanges at 8 years, and no change over a 4-year interval, it appears that bone ingrowth can be reliably expected to persist through the medium term.

This study sets a baseline against which more complex approaches to glenoid arthroplasty, such as metal backed and augmented components, can be compared.

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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).