Vault perforation after eccentric glenoid reaming for deformity correction in anatomic total shoulder arthroplasty
These authors evaluated variations in "correction" of glenoid deformity by eccentric reaming. They hypothesized that partial correction of modified Walch B/C-type glenoid deformities can achieve 75% bone implant contact area (BICA) with a reduced vault perforation risk compared with complete correction.
They retrospectively evaluated 50 shoulder computed tomographic scans with glenohumeral osteoarthritis using 3D planning software, simulating 3 eccentric reaming scenarios: no, partial, and complete deformity correction. Each scenario was evaluated at 4 BICAs and using 3 implant fixation types. Three-dimensional surface representations were used to evaluate medialization and vault perforation. Here's an example of perforation
The patients had mean glenoid retroversion and inclination of 18.5 and 8.8, respectively, and mean posterior humeral head subluxation of 76%. 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. The central and posterior-inferior implant components were most likely to perforate across all scenarios.
They concluded that eccentric reaming for glenoid deformity correction increases the risk of vault perforation. Trying to correct severe glenoid deformity resulted in increased medialization to achieve 75% BICA. Pegged implants had increased chances of perforation compared with a keeled design; the central and posterior-inferior components were most likely to perforate during deformity correction.
Comment: In our practice we prioritize preservation of bone stock over "version correction".
These authors evaluated variations in "correction" of glenoid deformity by eccentric reaming. They hypothesized that partial correction of modified Walch B/C-type glenoid deformities can achieve 75% bone implant contact area (BICA) with a reduced vault perforation risk compared with complete correction.
They retrospectively evaluated 50 shoulder computed tomographic scans with glenohumeral osteoarthritis using 3D planning software, simulating 3 eccentric reaming scenarios: no, partial, and complete deformity correction. Each scenario was evaluated at 4 BICAs and using 3 implant fixation types. Three-dimensional surface representations were used to evaluate medialization and vault perforation. Here's an example of perforation
The patients had mean glenoid retroversion and inclination of 18.5 and 8.8, respectively, and mean posterior humeral head subluxation of 76%. 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. The central and posterior-inferior implant components were most likely to perforate across all scenarios.
They concluded that eccentric reaming for glenoid deformity correction increases the risk of vault perforation. Trying to correct severe glenoid deformity resulted in increased medialization to achieve 75% BICA. Pegged implants had increased chances of perforation compared with a keeled design; the central and posterior-inferior components were most likely to perforate during deformity correction.
Comment: In our practice we prioritize preservation of bone stock over "version correction".
Our goal is achieve 100% bone implant contact area so that the component has maximal bony support. We find that changing glenoid version is not necessary to achieve a stable and functional arthroplasty. Instead, stability is established by soft tissue balancing and if necessary use of an anteriorly eccentric humeral head component as described in prior posts. Finally, using this component
we have found that central peg perforation is not a problem, instead it is consistent with excellent clinical and radiographic outcomes. Shown below is a glenoid component inserted in a retroverted glenoid with minimal reaming. The component is stable 5 years after surgery with excellent bone ingrowth among the flutes.
And here is a more recent case showing bone-preserving glenoid reaming without version correction and insertion of a glenoid component with anterior penetration of the fluted central peg. Note the excellent seating of the glenoid component with full bone implant contact. Note also the use of an anteriorly eccentric humeral component.
the patient had full shoulder function and stable radiographs at his most recent followup.
Prior reports have pointed to the inadvisability of incomplete seating (i.e. <100% of bone implant contact area), see this link. Less that 100% bone implant contact area is a particular concern if there is lack of contact to support the posterior glenoid, which receives the greatest load when the shoulder is flexed.
Here's a related post:
Glenoid vault perforation in total shoulder arthroplasty: Do we need computer guidance?
These authors point out that one of the goals of computer 3D simulation and computer-generated guides is to minimize perforation of the glenoid vault by glenoid pegs in shoulder arthroplasty, based on assumptions that perforation leads to worse outcomes because of component loosening and potential failure.
They evaluated outcomes of glenoid peg perforation testing the assumption that perforation produces worse results. Eighty-three shoulders underwent shoulder arthroplasty with pegged hybrid fixation (bone-ingrowth flanged central glenoid peg and peripheral cemented pegs) without the use of computer generated guides or 3D planning software.
Outcomes were determined by American Shoulder and Elbow Score and Oxford Shoulder Score. Fine slice CT determined the presence of vault perforation and the extent of lucent lines at the prosthesis–bone interface and bony morphology of the vault perforation. Follow-up was 46.7 months (24–99). Seven shoulders (8%) demonstrated perforation of glenoid vault. Bony ingrowth and cortical overgrowth occurred despite perforation, with no clinically significant differences in clinical or radiological outcomes in shoulders with and without glenoid vault perforation. None of these patients underwent revision surgery.
The presence of lucent lines around the glenoid component was classified on CT according to the scoring system of Yian et al. Yian described assessing six zones with the amount of lucency around pegs given a score of 1, 2 or 3 if there was lucency of 1, 2 or 3 mm. Possible Yian scores ranged from 0 to 18. They defined an abnormal Yian score as being > 0. Implants with a Yian scores of 6–12 or > 12 are defined as being possibly loose and definitely loose, respectively.
The presence of lucent lines around the glenoid component was classified on CT according to the scoring system of Yian et al. Yian described assessing six zones with the amount of lucency around pegs given a score of 1, 2 or 3 if there was lucency of 1, 2 or 3 mm. Possible Yian scores ranged from 0 to 18. They defined an abnormal Yian score as being > 0. Implants with a Yian scores of 6–12 or > 12 are defined as being possibly loose and definitely loose, respectively.
The authors conclude that "perforation of the glenoid vault by the central peg is not associated with inferior clinical and radiological outcomes in total shoulder arthroplasty. No statistically or clinically significant differences were found in shoulders with or without glenoid vault perforation. The perception that vault perforation leads to increased rates of failure and revision of total shoulder arthroplasty may be unfounded. The current trend of promoting patient specific guides for insertion needs more proof of improved outcome to justify significant extra expense."
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