Manual muscle testing of upper limb muscle strength in persons with tetraplegia undergoing surgical restoration of elbow extension: A scoping review

Tetraplegia often leads to upper limb disability due to triceps paralysis, affecting workspace and mobility. Restoring elbow extension via muscle-tendon or nerve transfer requires preoperative donor muscle strength assessment and postoperative evaluation. Manual muscle testing (MMT) is common, but inconsistencies in grading systems and procedures hinder cross-study comparisons. This study aims to examine how MMT is reported for assessing shoulder and elbow muscle strength in patients with tetraplegia undergoing elbow extension restoration. The review focuses on grading systems, targeted muscles, and testing procedures and positions used in MMT to advocate for standardization. A literature survey was conducted in September 2021 and repeated in September 2023 across five databases: Allied and Complementary Medicine Database, Embase, Medline, CINAHL, and Scopus. The search strategy utilized subject headings and keywords related to "upper limb reconstructive surgery," "tendon transfer surgery," "nerve transfer surgery," and "tetraplegia." Studies describing clinical information about assessment or outcomes of shoulder and elbow muscle strength using MMT in surgical elbow extension restoration in tetraplegia were included. Extracted data included study characteristics, surgical intervention, muscles tested, and description of how MMT is performed. These data were then analyzed to categorize and interpret existing practices. A total of 29 studies met the inclusion criteria. Among these, 66% focused on muscle-tendon, and 34% addressed nerve transfers. Donor strength was assessed preoperatively in 55% and postoperatively in 34%. Elbow extension strength was consistently reported postoperatively but only preoperatively in 83% of studies. Only five studies specified the positions used for muscle testing, but these positions varied. Despite numerous studies on elbow extension restoration outcomes in people with tetraplegia, there is no consistent approach for reporting muscle strength. Consistent reporting of pre- and postoperative muscle strength, including testing positions, is required to obtain standardized MMT positions. Similarly, the adoption of a universal scale could improve outcome reporting and synthesis.