Medialized versus Lateralized Humeral Implant in Reverse Total Shoulder Arthroplasty: The Comparison of Outcomes in Pseudoparalysis with Massive Rotator Cuff Tear.

Background With the increasing use of the lateralized humeral implants in reverse total shoulder arthroplasty (RTSA), it is still unclear whether or not this design will be as advantageous as the medialized humeral implants in the setting of pseudoparalysis (PP). Methods A total of 51 eligible RTSA cases for PP signs due to massive rotator cuff deficiency were selected for the retrospective review. Twenty-five patients were allocated to Group L in which the isolated humeral side lateralization was performed (neck-shaft angle of 145°), and 26 patients were allocated to Group M (neck-shaft angle of 155°). Preoperative and postoperative radiological measurements including critical shoulder angle (CSA), acromiohumeral distance (AHD), lateral humeral offset (LHO) and deltoid wrapping offset (DWO), as well as range of motion (ROM) and clinical outcome scores were compared. The average age was 71.0±6.5 years for Group L, and 70.3±7.0 years for Group M, and the overall average follow-up period was 49.0±13.5 months (range, 25.7-68.9). Results The preoperative radiological measurements were similar, but the postoperative LHO and DWO were significantly larger for Group L, whereas the postoperative AHD was larger for Group M compared to Group L, with the values being 39.8±9.7mm and 33.6±10.4mm, respectively (P=0.034). For the ROM, active forward elevation did improve significantly for both, starting preoperatively with the active ranges of 39°±19° (passively 153°±24°) for Group L and 42°±18° (passively 156°±11°) for Group M, and the final postoperative active ranges being 142°±16° and 133°±33° respectively, without significant difference between the groups (P=0.426). The postoperative recovery of PP for Group L was 100% (25 of 25) whereas for Group M, it was 96.2% (25 of 26). The final Visual Analog Scores (VAS) and University of California Los Angeles scores (UCLA) improved significantly for both groups, but the differences between the groups at the final assessments were insignificant. The four complications were peri-prosthetic fracture, acromial stress fracture, peri-prosthetic joint infection and neuropraxia, all of which were in Group M, and scapular notching with higher grades were more prevalent for Group M (26.9%, 7 of 26). Conclusions With the RTSA, good outcomes and recovery were achieved in most cases of pseudoparalysis. The postoperative active elevation range and functional outcomes were not affected by medialization or lateralization of the humeral implant. Earlier recovery of motion was observed with the lateralized group but no significant differences were seen in the final range of motion between the groups.