Geometrical analysis of stemless shoulder arthroplasty: a radiological study of seventy TESS total shoulder prostheses.

PURPOSE

The aim of this study was to investigate the ability of a stemless shoulder prosthesis to restore shoulder anatomy in relation to premorbid anatomy.

METHODS

This prospective study was performed between May 2007 and December 2013. The inclusion criteria were patients with primary osteoarthritis (OA) who had undergone stemless total anatomic shoulder arthroplasty. Radiographic measurements were done on anteroposterior X-ray views of the glenohumeral joint.

RESULTS

Sixty-nine patients (70 shoulders) were included in the study. The mean difference between premorbid centre of rotation (COR) and post-operative COR was 1 ± 2 mm (range -3 to 5.8 mm). The mean difference between premorbid humeral head height (HH) and post-operative HH was -1 ± 3 mm (range -9.7 to 8.5 mm). The mean difference between premorbid neck-shaft angle (NSA) and post-operative NSA was -3 ± 12° (range -26 to 20°).

CONCLUSIONS

Stemless implants could be of help to reconstruct the shoulder anatomy. This study shows that there are some challenges to be addressed when attempting to ensure optimal implant positioning. The critical step is to determine the correct level of bone cut to avoid varus or valgus humeral head inclination and ensure correct head size.