Does proximal porous coating in short-stem humeral arthroplasty reduce stress shielding?

Abstract

Context: Short-stem humeral designs in shoulder arthroplasty have been introduced recently. A retrospective cohort study was conducted to determine if newer proximal porous titanium coating in humeral short stems produced clinical and radiologic improvements. Method: Short-stem humeral implants (Tornier Ascend, Wright Medical) were used in 46 anatomical total shoulder replacements from October 2012 to December 2015. Clinical and radiologic measures were analyzed at one-and twoyear follow-up. Results: Nineteen shoulders received earlier grit blasted stems (Ascend Monolithic), and 27 shoulders received the later stems with proximal titanium porous coating (Ascend Flex). At two-year follow-up, radiographic changes and stress shielding were similar. Medial cortical thinning were more frequently observed in Monolithic (18 of 19) compared to Flex stems (19 of 27) on the PA films, though this was not statistically significant (P ¼ 0.061). Clinical outcome scores improved regardless of the stem type used and independent of the radiologic adaptations on plain films. One participant with the Ascend Flex developed glenoid component failure and rotator cuff tear and was subsequently revised. Discussion: Clinical and radiological outcomes are similar in both short-stem designs. Proximal titanium porous coating may reduce medial calcar cortical thinning but it does not prevent it. Key message: When compared to similarly designed uncoated grit-blasted stems, proximally porous coated humeral short stems produced similar clinical and radiological results. The proximal titanium porous coating may reduce medial cortical thinning.

Periprosthetic Stress Shielding of the Humerus after Reconstruction with Modular Shoulder Megaprostheses in Patients with Sarcoma

“…While there are few data available on stress shielding around megaprosthetic stems, this issue has been investigated in multiple studies on conventional shoulder arthroplasty [ 15 , 29 , 30 ]. Denard et al compared stress shielding between 58 standard stems and 56 short stems following (anatomical) total shoulder arthroplasty (TSA) [ 12 ].…”

Porous versus solid shoulder implants in humeri of different bone densities: A finite element analysis

“…Furthermore, it is also important to consider the potential mechanobiological impact that porous stems may have on surrounding bone. Previous studies of proximal humeral implants for the shoulder have used computational models, radiographic and clinical outcomes postoperatively to examine the effects of stem length (Razfar et al, 19 Aibinder et al, 20 Denard et al, 21 ) hollow stems (Soltanmohammadi et al, 22 ) cementing (Denard et al, 23 Kim et al 24 ) and coatings (Tan et al 25 ) Porous humeral stems, however, have not been investigated.…”