Posterior Glenoid Wear in Total Shoulder Arthroplasty: Eccentric Anterior Reaming Is Superior to Posterior Augment

Abstract

Background Uncorrected glenoid retroversion during total shoulder arthroplasty may lead to an increased likelihood of glenoid prosthetic loosening. Augmented glenoid components seek to correct retroversion to address posterior glenoid bone loss, but few biomechanical studies have evaluated their performance. Questions/purposes We compared the use of augmented glenoid components with eccentric reaming with standard glenoid components in a posterior glenoid wear model. The primary outcome for biomechanical stability in this model was assessed by (1) implant edge displacement in superior and inferior edge loading at intervals up to 100,000 cycles, with secondary outcomes including (2) implant edge load during superior and inferior translation at intervals up to 100,000 cycles, and (3) incidence of glenoid fracture during implant preparation and after cyclic loading. Methods A 12°-posterior glenoid defect was created in 12 composite scapulae, and the specimens were divided in two equal groups. In the posterior augment group, glenoid version was corrected to 8°and an 8°-augmented polyethylene glenoid component was placed. In the eccentric reaming group, anterior glenoid reaming was performed to neutral version and a standard polyethylene glenoid component was placed. Specimens were cyclically loaded in the superoinferior direction to 100,000 cycles. Superior and inferior glenoid edge displacements were recorded. Results Surviving specimens in the posterior augment group showed greater displacement than the eccentric reaming group of superior (1.01 ± 0.02 [95% CI, 0.89-1.13] versus 0. 83 ± 0.10 [95% CI,

Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty?

“…Authors have expressed concern regarding inferior clinical outcomes when standard glenoid components are inserted in more than 15°retroversion, leading surgeons to seek approaches for changing glenoid version in TSAs [5,7,10,16,21,34,40,44,49,59]. While arthritic shoulders with substantial preoperative retroversion represent a more-severe form of glenohumeral arthritis, it remains unclear whether, as suggested by some authors [3,6,10,17,47], the clinical results of inserting a standard glenoid component in 15°or more retroversion are inferior to those obtained when the glenoid component is inserted in less than 15°retroversion.…”

“…Several methods to address increased glenoid retroversion have been described [5,21,46], including overreaming the anterior ''high side'' of the glenoid (Fig. 1) [14,59], posterior glenoid bone grafting [16,34,43], posteriorly augmented glenoid components [40,44,49,64], and reverse total shoulder arthroplasty (TSA) [33].…”

Anatomic Augmented Glenoid Implants for the Management of the B2 Glenoid

“…A number of studies have evaluated the stability of glenoid augments, either as a comparison of various implants or against other techniques. 57,[59][60][61][62][63][64] In 2012, Kirane et al established the potential for glenoid augments in their cadaver study of 2 novel prototypes. They found that there were not significant differences in the loading-induced peri-glenoid strain between a traditional total shoulder arthroplasty in shoulders without bony defects and the total shoulder arthroplasty performed with a polyethylene step block performed in shoulders with a biconcave posterior bony deficit, while strain was higher in a model with titanium step blocks.…”

The arthritic glenoid: anatomy and arthroplasty designs

“…Recent clinical [19•, 20, 21], experimental [22][23][24][25][26], and computational [27][28][29][30][31] studies addressing asymmetric posterior glenoid erosion have focused on eccentric reaming and/or retroversion correction. It has been suggested that retroversion correction greater than 15°cannot be achieved with eccentric reaming alone [26,32].…”