Risk of Perforation Is High During Corrective Reaming of Retroverted Glenoids: A Computer Simulation Study.

BACKGROUND: Corrective anterior reaming is an accepted method for addressing retroversion in a biconcave retroverted (Walch classification, type B2) glenoid in anatomic total shoulder arthroplasty. However, concern still exists regarding early glenoid component failure in the setting of severe retroversion, which may be related to loss of component containment and/or violation of subchondral bone resulting from reaming. The goal of this study was to determine what characteristics of B2 glenoids are less amenable to corrective reaming by virtually implanting anatomic glenoid components. QUESTIONS/PURPOSES: (1) How much medial reaming is required to correct the version of a B2 glenoid to an acceptable position? (2) Are glenoids with more severe retroversion (> 25°) at higher risk of component perforation than less retroverted glenoids? (3) Is correcting to 10° of retroversion associated with greater risk as compared with reaming to 15°? (4) How does corrective reaming affect the underlying bone density on the glenoid face of B2 glenoids? METHODS: A series of 71 patients with B2 glenoids (posterior subluxation of the humeral head with posterior bone loss) with CT scans who were indicated for shoulder arthroplasty were reviewed. Forty-four of 71 glenoids (62.5%) had < 25° of native retroversion. Anatomic glenoid implants were then virtually implanted using three-dimensional CT software that allows for preoperative shoulder arthroplasty planning to correct native retroversion to 15° or 10° of retroversion using both a central peg with an inverted triangle peg configuration or a keel. The amount of reaming of the anterior glenoid required to correct retroversion, perforation of peripheral pegs, or keel was compared. Additionally, assessment of the surface area of the glenoid that had poor bone density (defined as cancellous bone under the subchondral plate) was analyzed by the software after correction. RESULTS: Correction to 15° of retroversion required 5 ± 3 mm of reaming, and correction to 10° of retroversion required 8 ± 3 mm of reaming to obtain at least 80% seating. Peripheral peg perforation with correction to 15° occurred in 15 of 27 (56%) glenoids with > 25° of retroversion compared with 10 of 44 (23%) of glenoids with < 25° of retroversion (relative risk [RR], 2.4; 95% confidence interval [CI], 1.3-4.6; p = 0.006). There was no difference in perforation with keeled components. Increased correction to 10° did not increase the risk of component perforation. When correction to 15°, glenoids with higher native version (> 25°) had a greater risk of poor bone quality support (10 of 27 [37%]) when compared with glenoids with less version (four of 44 [9%]; RR, 4.1; 95% CI, 1.5-12.8; p = 0.006). Increased correction resulted in 13 of 27 (48%) glenoids with version > 25° having poor bone density versus 10 of 44 (23%) with ≤ 25° of version (RR, 2.1; 95% CI, 1.1-4.1; p = 0.028). CONCLUSIONS: There is a high risk of vault perforation after corrective reaming. Glenoid retroversions > 25° are at a higher risk of having poor bone quality supporting the component. CLINICAL RELEVANCE: When contemplating options for patients with severe retroversion, surgeons should consider alternatives other than corrective reaming if achieving normal glenoid version is desired.

La artroplastia invertida de hombro ante defectos óseos glenoideos / Reverse shoulder arthroplasty due to glenoid bone defects

Objetivo. La artroplastia invertida se está convirtiendo en una herramienta útil para afecciones muy variadas en el hombro. Un defecto óseo importante de la glena puede afectar a la fijación del componente glenoideo. El propósito de nuestro estudio es evaluar a medio plazo los resultados de la artroplastia invertida de hombro asociados a una glenoplastia. Material y métodos. Se realizó un estudio retrospectivo de 5 pacientes de nuestro hospital con defectos glenoideos de distinta etiología que fueron tratados mediante artroplastia invertida de hombro asociada a glenoplastia. Resultados. El seguimiento mínimo de estos pacientes fue de un año (con una media de 30,4 meses). Todos los injertos estaban radiológicamente integrados, sin observarse signos de resorción o necrosis. A los 12 meses el test de Constant era de 66,75 de media y el EVA medio era de 1. Discusión. La glenoplastia es una intervención de alta demanda técnica que consigue restaurar el remanente óseo en pacientes con defectos estructurales, permitiendo así implantar una artroplastia invertida. De esa forma podemos mejorar la función y la clínica en pacientes con diversas afecciones glenohumerales, proporcionándoles una solución (AU)

Objective. Reverse shoulder arthroplasty is becoming a useful tool for many diseases of the shoulder. Any severe glenoid bone defect may affect the fixing of the glenoid component. The aim of this paper is to evaluate the medium-term outcomes of reverse shoulder arthroplasty associated with a glenoplasty. Materials and methods. A retrospective study was conducted on 5 patients from our hospital, selected due to glenoid defects of different etiology. All of them where treated with reverse shoulder arthroplasty associated with glenoplasty with bone graft. Results. The minimum follow-up was one year (mean 30.4 months). All grafts were radiologically integrated, with no signs of resorption or necrosis being observed. At 12 months, the Constant score was 66.75 and the mean EVA score was 1. Discussion. Glenoplasty surgery is technically demanding for restoring original bone size in patients with glenoid structural defects, enabling a reverse shoulder arthroplasty to be implanted. Thus improving both the function and clinical outcomes in selected patients with glenohumeral pathology and providing them with a solution (AU)