These authors evaluated the effects of the correction of glenoid deformity by eccentric reaming using CT scans fo 50 shoulders. They modeled three reaming scenarios:(1) no correction of glenoid version and inclination, (2) partial correction of glenoid version and inclination and (3) complete correction of glenoid version and inclination.
Three-dimensional surface representations were used to evaluate medialization and vault perforation.
The patients had mean glenoid retroversion and inclination of 18.5 and 8.8, respectively, and 76% mean posterior humeral head displacement relative to the plan of the scapula.
Pegged implants had increased rates of perforation compared with a keeled design. The central and posterior-inferior implant components were most likely to perforate across all scenarios.
They hypothesized that partial correction of Walch B/C-type glenoid deformities can achieve 75% bone implant contact area (BICA) with a reduced vault perforation risk compared with complete correction. Each scenario was evaluated at 4 BICAs and using 3 implant fixation types.
The patients had mean glenoid retroversion and inclination of 18.5 and 8.8, respectively, and 76% mean posterior humeral head displacement relative to the plan of the scapula.
With 75% BICA, the 3 fixation types had glenoid vault perforation in 6%-26% and 26%-54% of cases for partial and complete glenoid deformity correction, respectively.
In the scemario 1 without glenoid deformity correction, the Cortiloc implant had a 10%-14% chance of perforation for a 75%-95% implant seating (Fig. 10). In scenario 2, partial correction of the glenoid version resulted in a 26%-42% chance of perforation for a 75%-95% implant seating, whereas in scenario 3, complete correction of the glenoid version resulted in a 54%- 68% chance of perforation for a 75%-95% implant seating.
Complete correction of glenoid version and inclination nearly doubled the perforation risk seen with partial correction using the Cortiloc implant.
Comment: This paper brings up three important points.
First, it seems important to preserve glenoid bone stock; over-reaming can compromise the quality of fixation as well as the opportunities for revision, should it become necessary.
Second, we do not know how important it is to avoid glenoid perforation (shown in red in the illustration below)?
Perforation of the cortex might even augment fixation, as it does with the screws of a reverse total shoulder.
Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty?
In a population of patients undergoing TSA in whom no specific efforts were made to change the version of the glenoid, these authors asked whether at 2 years after surgery patients having glenoid components implanted in 15° or greater retroversion had (1) less improvement in the Simple Shoulder Test (SST) score and lower SST scores; (2) higher percentages of central peg lucency, higher Lazarus radiolucency grades, higher mean percentages of posterior decentering, and more frequent central peg perforation; or (3) a greater percentage having revision for glenoid component failure compared with patients with glenoid components implanted in less than 15° retroversion. They examined the records of 201 TSAs performed using a standard all-polyethylene pegged glenoid component
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%).
The 2-year SST scores for the retroverted (9.3 ± 2.9) and the nonretroverted glenoid groups (9.4 ± 3.0) were similar.
No patient in either group reported symptoms of subluxation or dislocation.
The radiographic results for the retroverted glenoid group were not significantly different from those for the nonretroverted group with respect to central peg lucency (four of 21 [19%] versus six of 50 [12%], average Lazarus radiolucency scores (0.5 versus 0.7,), and the mean percentage of posterior humeral head decentering (3.4% ± 5.5% versus 1.6% ± 6.0%).
The percentage of patients with retroverted glenoids undergoing revision (0 of 21 [0%]) was not inferior to the percentage of those with nonretroverted glenoids undergoing revision (three of 50; [6%]).
The authors concluded that in this series of TSAs, postoperative glenoid retroversion was not associated with inferior clinical or radiographic results at 2 years after surgery.
Complete correction of glenoid version and inclination nearly doubled the perforation risk seen with partial correction using the Cortiloc implant.
Comment: This paper brings up three important points.
First, it seems important to preserve glenoid bone stock; over-reaming can compromise the quality of fixation as well as the opportunities for revision, should it become necessary.
Second, we do not know how important it is to avoid glenoid perforation (shown in red in the illustration below)?
Consider the case illustrated below with two year post operative x-rays. Even though there is penetration of the glenoid vault by the central peg (arrow below left), there is complete integration of bone into the flutes of the peg (arrow below right).
Here's a previous post on the topic "Glenoid perforation with pegged components during total shoulder arthroplasty." (see this link)
Third, we do not know how important it is to correct preoperative glenoid retroversion of, say, 18 degrees. Consider the article below.
Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty?
In a population of patients undergoing TSA in whom no specific efforts were made to change the version of the glenoid, these authors asked whether at 2 years after surgery patients having glenoid components implanted in 15° or greater retroversion had (1) less improvement in the Simple Shoulder Test (SST) score and lower SST scores; (2) higher percentages of central peg lucency, higher Lazarus radiolucency grades, higher mean percentages of posterior decentering, and more frequent central peg perforation; or (3) a greater percentage having revision for glenoid component failure compared with patients with glenoid components implanted in less than 15° retroversion. They examined the records of 201 TSAs performed using a standard all-polyethylene pegged glenoid component
inserted after conservative glenoid reaming without specific attempt to modify preoperative glenoid version.
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%).
The 2-year SST scores for the retroverted (9.3 ± 2.9) and the nonretroverted glenoid groups (9.4 ± 3.0) were similar.
No patient in either group reported symptoms of subluxation or dislocation.
The radiographic results for the retroverted glenoid group were not significantly different from those for the nonretroverted group with respect to central peg lucency (four of 21 [19%] versus six of 50 [12%], average Lazarus radiolucency scores (0.5 versus 0.7,), and the mean percentage of posterior humeral head decentering (3.4% ± 5.5% versus 1.6% ± 6.0%).
The percentage of patients with retroverted glenoids undergoing revision (0 of 21 [0%]) was not inferior to the percentage of those with nonretroverted glenoids undergoing revision (three of 50; [6%]).
The authors concluded that in this series of TSAs, postoperative glenoid retroversion was not associated with inferior clinical or radiographic results at 2 years after surgery.
It is apparent that further study is needed to understand the best approach to glenoid fixation for the different types of glenoid pathoanatomy.
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To see a YouTube of our technique for total shoulder arthroplasty, click on this link.
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