A multiplanar humeral head osteotomy results in significantly improved bone compression strength compared to a standard humeral head osteotomy in stemless total shoulder arthroplasty

When performing anatomic total shoulder arthroplasty, modular stemmed humeral implants are the most frequently used. However, there has been renewed interest in the use of stemless humeral components to preserve bone stock and better reproduce native anatomy. The use of stemless implants in patients with poor metaphyseal bone quality is controversial. Recently, a technique was developed using a multiplanar osteotomy (MPO) of the humeral head, which preserves the subchondral bone and potentially improves stemless implant fixation. The effect of MPO on compressive bone strength has not yet been studied. The purpose of our study is to compare the bone compression strength between humeral heads prepared with either a standard humeral head cut or an MPO.

Ten matched pairs of fresh-frozen humeral heads were used. For each pair, one humeral head underwent a standard humeral neck cut using a cutting guide, with the opposite matched head undergoing an MPO. Each humeral head subsequently underwent compression testing using a 1.3 mm steel needle at a standard speed of 1 mm/s in a grid pattern across the cut surfaces of the humeral head. Maximum force was recorded and compared with each corresponding point on the opposite matched pair.

Mean maximum compression force across all points was significantly higher in the MPO group (97 ± 41 N) compared to the standard cut group (52 ± 26 N). Maximum compression force across each matched pair was higher in the MPO group in all samples and was statistically significant in 8 of the 10 samples.

This study demonstrates that use of an MPO to prepare the humeral head results in significantly increased bone compression strength compared to a standard cut, with the potential to improve stemless implant fixation.