Cement augmentation of glenoid baseplate screws does not improve primary stability in reversed shoulder arthroplasty: A cadaveric study.

INTRODUCTION: Cuff tear arthritis and complex proximal humeral fractures are common pathologies that are frequently addressed by the implantation of a reversed shoulder prosthesis. The present cadaveric study aimed to analyze the effect of cement augmentation of the glenoid component on the primary stability in geriatric patients.

HYPOTHESIS: Cement augmentation of glenoid baseplate screws has an influence on primary stability in reversed shoulder arthroplasty (RSA).

MATERIALS AND METHODS: Glenoid base plates (Delta Xtend, DePuy Synthes, Westchester, USA) were implanted in 6 pairs of formalin-fixated scapulae of 4 female and 2 male donors (average age 83 years). Two angle stable screws were placed at the superior and inferior position. Cement augmentation was performed with 2ml bone cement (Kyphon, Medtronic, Minneapolis, USA) per screw in right specimens. Afterwards, biomechanical testing with 600 to 1000N (100 cycles) at a 65° abduction angle was performed. Finally, a load-to-failure analysis was conducted.

RESULTS: No implant loosening was observed during cyclic tests from 600N to 1000N. In addition no difference in the plastic deformation was detected at 600N (p=0.301), 700N (p=0.522), 800N (p=0.480), 900N (p=0.521) and 1000N (p=0.748). Load-to-failure analyses revealed implant loosening at 3314N (SD 823N) in the cement-augmented implants and at 3059N (SD 974N) in scapulae with non-cemented screws (p=0.522).

DISCUSSION: Cement-augmented fixation of the glenoid component did not result in an increased primary stability in this study. Thus, the application of cement should be critically assessed considering associated risks and increased costs.

LEVEL OF PROOF: Basic science study, controlled laboratory study.