Accuracy of Glenoid Component Placement in Total Shoulder Arthroplasty and Its Effect on Clinical and Radiological Outcome in a Retrospective, Longitudinal, Monocentric Open Study

Abstract

BackgroundThe success of Total Shoulder Arthroplasty (TSA) is believed to depend on the restoration of the natural anatomy of the joint and a key development has been the introduction of modular humeral components to more accurately restore the patient’s anatomy. However, there are no peer-reviewed studies that have reported the degree of glenoid component mal-position achieved in clinical practice and the clinical outcome of such mal-position. The main purpose of this study was to assess the accuracy of glenoid implant positioning during TSA and to relate it to the radiological (occurrence of radiolucent lines and osteolysis on CT) and clinical outcomes.Methods68 TSAs were assessed with a mean follow-up of 38+/−27 months. The clinical evaluation consisted of measuring the mobility as well as of the Constant Score. The radiological evaluation was performed on CT-scans in which metal artefacts had been eliminated. From the CT-scans radiolucent lines and osteolysis were assessed. The positions of the glenoid and humeral components were also measured from the CT scans.ResultsFour position glenoid component parameters were calculated The posterior version (6°±12°; mean ± SD), the superior tilt (12°±17°), the rotation of the implant relative to the scapular plane (3°±14°) and the off-set distance of the centre of the glenoid implant from the scapular plane (6±4 mm). An inferiorly inclined implant was found to be associated with higher levels of radiolucent lines while retroversion and non-neutral rotation were associated with a reduced range of motion.Conclusionthis study demonstrates that glenoid implants of anatomic TSA are poorly positioned and that this malposition has a direct effect on the clinical and radiological outcome. Thus, further developments in glenoid implantation techniques are required to enable the surgeon to achieve a desired implant position and outcome.

The Envelope of Physiological Motion of the First Carpometacarpal Joint

“…In addition to advancing our basic understanding of CMC joint function, an accurate and complete understating of CMC kinematics provides a basis for evaluating CMC pathology, such as mechanically mediated aspects of OA [14], and it can inform the design of implants, where accurate replication of kinematics is essential for long-term success [15][16][17]. There is growing clinical evidence that implant failure is associated with the failure to replicate normal kinematics in the spine [31][32][33][34][35][36], wrist [37], knee [38,39], and shoulder [40][41][42][43][44][45]. In modeling, simplifying the thumb CMC joint as a ball-and-socket articulation rather than with the more complex harmonic profiles we identified, where the location of the screw axis can vary by >1 cm, could lead to substantial errors in the computation of ligament strains, cartilage stresses, and muscle moment arms.…”

Controversies in Shoulder Arthroplasty

“…To assess glenoid component version as it relates to patient outcomes, Ho et al 14 reported increased signs of radiographic loosening when cemented glenoid components were inserted in >15 degrees of retroversion. Gregory et al, 49 in their prospective outcomes study, suggested that ideal glenoid component insertion should be 0 degrees of version to slight retroversion; they reported no negative effects of anteversion. Overall, there are few high-quality studies assessing the effects of glenoid version on implant survivability, and the best available evidence suggests a broad range for acceptable version (0 to 15 degrees of retroversion).…”

“…Normal, nonpathologic glenoids are reported to typically have superior inclination between 4 and 12 degrees. Gregory et al 49 assessed their arthroplasty outcomes with respect to inclination and reported an ideal range between 0 and 20 degrees of superior inclination. They found that inferior tilt or declination was associated with increased radiolucent lines around the glenoid component.…”

Benefit of intraoperative navigation on glenoid component positioning during total shoulder arthroplasty

“…While we did see a significant improvement in version statistically, we cannot gauge the clinical relevance of the extent of this change at roughly 6°. Moska et al [21], as well as Gregroy et al [8], have suggested that version in excess of 20°is associated with poorer outcomes, but no clear cut correlation between extent of version and risk of failure has been established yet, suggesting that some error in positioning is tolerated.…”