2025 ISAKOS Biennial Congress ePoster
Influence Of Lateralization And Distalization On Joint Function After Primary Reverse Total Shoulder Arthroplasty
Arianna Carnevale, PhD, Roma, Roma ITALY
Edoardo Franceschetti, MD, Roma, Rome ITALY
Emiliano Schena, Eng, Rome, --- Select One --- ITALY
Alessandra Berton, MD, Latina, LT ITALY
Vincenzo Candela, MD, PhD ITALY
Giuseppe Salvatore, MD, PhD, Roma ITALY
Giovanni Perricone, MD, Rome, Rome ITALY
Marco Edoardo Cardinale, MD, Rome ITALY
Giulia Cozza ITALY
Rocco Papalia, MD, PhD, Prof., Rome ITALY
Umile Giuseppe Longo, MD, MSc, PhD, Prof., Rome ITALY
Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Lazio, ITALY
FDA Status Not Applicable
Summary
The purpose of this study was to investigate how lateralization shoulder angle (LSA) and distalization shoulder angle (DSA) are related to clinical and kinematic outcomes after reverse total shoulder arthroplasty. Thirty-three patients were evaluated. The study pointed out that positioning the prosthetic implant with higher LSA values could lead to higher IR peak values and IR ROM after RTSA.
Abstract
Background
Reverse total shoulder arthroplasty (RTSA) is one of the most common surgical procedures performed in patients affected by several shoulder diseases. Lateralization and distalization of prosthetic implants were previously identified as two main influencing factors affecting shoulder biomechanics after surgery. Lateralization and distalization have an impact on the position of the new center of rotation of the joint, the forces at the bone–implant interface, the implant stability, and the deltoid’s lever arm and pre-tensioning. The overall lateralization and distalization are due to the design and size of the components of the implant, their positioning, and the surgical technique
AIMS
The purpose of this study was to investigate how lateralization shoulder angle (LSA) and distalization shoulder angle (DSA) are related to clinical and kinematic outcomes after reverse total shoulder arthroplasty.
Methods
Thirty-three patients were evaluated at least six months postoperatively. The Single Assessment Numeric Evaluation (SANE), Constant Murley Score (CMS), Simple Shoulder Test (SST), and Visual Analogue Scale (VAS) were used. Shoulder kinematics was evaluated with a stereophotogrammetric system. LSA and DSA inter-rater reliability was analysed through the interclass correlation coefficient (ICC). Stepwise forward linear regression analysis was conducted between LSA and DSA with clinical scales and kinematic measures, between which a correlation analysis was conducted.
Results
The inter-rater reliability for LSA (mean ICC = 0.93) and DSA (mean ICC = 0.97) results were good to excellent. Greater LSA values were associated with higher peaks of internal rotation (p = 0.012, R2 = 0.188) and range of motion (ROM) (p = 0.037, R2 = 0.133). SANE (p = 0.009), CMS (p = 0.031), and SST (0.026) were positively correlated to external rotation, while VAS (p = 0.020) was negatively related. Abduction peaks were positively related to CMS (p = 0.011) and SANE (p = 0.037), as well as abduction ROM (SANE, p = 0.031; CMS, p = 0.014).
Discussion
Identifying easily available and reproducible indexes of lateralization and distalization related to RTSA outcomes could provide surgeons with guidelines about optimal implant positioning. The study pointed out that positioning the prosthetic implant with higher LSA values could lead to higher IR peak values and IR ROM after RTSA. However, the association of LSA and DSA with other kinematic and clinical outcomes was not statistically significant. Further studies are needed to assess the clinical significance of these results because of the small sample available for this analysis and the great number of variables that could influence RTSA outcomes.