Abstract
BackgroundScapular dyskinesis, i.e., the deviant mobility or function of the scapula, hampers upper limb function in daily life. A typical sign of scapular dyskinesis is a scapula alata—a protrusion of the shoulder blade during arm elevation. While some reversible causes of scapula alata can be treated with therapy, other, irreversible causes require invasive surgical interventions. When surgery is not an option, however, severe limitations arise as standard approaches for assisting the scapula in daily life do not exist. The aim of this study was to quantify functional improvements when external, i.e., non-invasive, scapula assistance is provided.MethodsThe study was designed as a randomized controlled crossover trial. Eight participants with a scapula alata due to muscular dystrophy performed arm elevations in shoulder flexion and abduction while unassisted (baseline), externally assisted by a trained therapist, and externally assisted by a novel, textile-based scapula orthosis.ResultsWith therapist assistance, average arm elevation increased by 17.3° in flexion (p < 0.001, 95% confidence interval of the mean C{I}_{95%}=hspace{0.17em}left[9.8^circ , 24.9^circ right]), and by 11.2° in abduction (p < 0.01, C{I}_{95%}=left[4.7^circ , 17.7^circ right]), constituting the potential of external scapula assistance. With orthosis assistance, average arm elevation increased by 6.2° in flexion (C{I}_{95%}=left[0.4^circ ,11.9^circ right]) and by 5.8° in abduction (C{I}_{95%}=left[3.0^circ ,8.5^circ right]). Remarkably, in three participants, the orthosis was at least as effective as the therapist. Moreover, orthosis assistance reduced average perceived exertion by 1.25 points (Borg Scale) when elevating a filled bottle during a simulated daily living task.ConclusionThese findings indicate a large potential for future advancements in orthotics. Already now, the textile-based scapula orthosis presented here is a feasible tool for leveraging the benefits of external scapula assistance when a therapist is unavailable, as encountered in daily life scenarios.Trial Registration ClincalTrials.gov (ID NCT04154098). Registered: November 6th 2019, https://clinicaltrials.gov/ct2/show/NCT04154098?term=scapula+orthosis&draw=2&rank=1Graphic abstract
Highlights
IntroductionI.e., the deviant mobility or function of the scapula, hampers upper limb func‐ tion in daily life
Scapular dyskinesis, i.e., the deviant mobility or function of the scapula, hampers upper limb func‐ tion in daily life
The consistent and instantaneous nature of the improvements seen in this study strongly suggests that external scapula assistance has the potential to effectively increase upper limb function, and is a feasible, more flexible and much less invasive alternative to surgical interventions during therapy and in daily life
Summary
I.e., the deviant mobility or function of the scapula, hampers upper limb func‐ tion in daily life. A typical sign of scapular dyskinesis is a scapula alata—a protrusion of the shoulder blade during arm elevation. The dynamic stability of the shoulder joint complex is the bedrock for the versatile mobility of the human upper limb [1]. Connected to the trunk via the clavicle, the upper arm rotates within the scapula, a conjunction that can be approximated as a ball and socket joint. This inherently unstable structure is primarily kept together by the co-contracting muscles of the upper trunk and shoulder [1]
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