Intraoperative measurements of reverse total shoulder arthroplasty contact forces

J Exp Orthop. 2020 Dec 8;7(1):98. doi: 10.1186/s40634-020-00311-0.

Abstract

Purpose: Instability and fractures may result from tensioning errors during reverse total shoulder arthroplasty (RTSA). To help understand tension, we measured intraoperative glenohumeral contact forces (GHCF) during RTSA.

Methods: Twenty-six patients underwent RTSA, and a strain gauge was attached to a baseplate, along with a trial glenosphere. GHCF were measured in passive neutral, flexion, abduction, scaption, and external rotation (ER). Five patients were excluded due to wire issues. The average age was 70 (range, 54-84), the average height was 169.5 cm (range, 154.9-182.9), and the average weight was 82.7 kg (range, 45.4-129.3). There were 11 females and 10 males, and thirteen 42 mm and 8 38 mm glenospheres.

Results: The mean GHCF values were 135 N at neutral, 123 N at ER, 165 N in flexion, 110 N in scaption, and 205 N in abduction. The mean force at terminal abduction is significantly greater than at terminal ER and scaption (p < 0.05).

Conclusions: These findings could help reduce inappropriate tensioning.

Keywords: Abduction; External rotation; Intraoperative glenohumeral contact forces; Intraoperative tensioning; Reverse total shoulder arthroplasty; Scaption.