Purpose/Aim: There have been conflicting results regarding which muscle contribute most to the elbow spastic flexion deformity. This study aimed to investigate whether flexor spasticity of the elbow changed according to the position of the forearm, and to determine the muscle or muscles that contributed most to the elbow spastic flexion deformity by clinical examination.
Methods: This study is a single group, observational and cross-sectional study. Sixty patients were assessed for elbow flexor spasticity in different forearm positions (pronation, neutral and supination) with Modified Tardieu Scale. The primary outcome measure was a domain of the Modified Tardieu Scale, the dynamic component of spasticity (spasticity angle).
Results: In general, there was a significant difference between forearm positions regarding spasticity angle (p < .001). In pairwise comparisons, median spasticity angles in pronation (70 degrees) and neutral position (60 degrees) were significantly higher than those in supination (57.5 degrees) (adjusted p < .001 and adjusted p = .003, respectively). However, median spasticity angle in pronation did not differ significantly from those in neutral position in favour of pronation (adjusted p = .274).
Conclusions: The severity of spasticity changes according to the elbow position which suggests that the magnitude of contribution of each elbow flexor muscle to spastic elbow deformity is different. Reduction of spasticity from pronation to supination leads us to consider brachialis as the most spastic muscle. Since biceps was suggested to be the least spastic muscle in this study, and also to avoid spastic pronation deformity of the forearm, it should be rethought before performing chemodenervation into biceps muscle.
Keywords: Elbow joint; forearm position; muscle spasticity; stroke.