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An electromyography study of wrist extension orthoses and upper-extremity function
S Bulthaup1, D J Cipriani, J J Thomas
1Medical College of Ohio, Toledo, USA.
Summary
Wearing a wrist extension orthosis increases muscle activity in the shoulder and elbow. This finding is important for prescribing orthoses, particularly for individuals with existing proximal joint issues.
Area of Science:
- Biomechanical engineering
- Rehabilitation medicine
- Human movement science
Background:
- Wrist extension orthoses are commonly prescribed to manage various hand and wrist conditions.
- The impact of these orthoses on proximal muscle activity is not fully understood.
- Understanding this relationship is crucial for optimizing treatment and preventing secondary complications.
Purpose of the Study:
- To investigate the effects of commercially available wrist extension orthoses (long and short styles) on proximal shoulder and elbow muscle activity.
- To assess the influence of these orthoses on wrist flexor and extensor muscle activity.
- To compare the muscle recruitment patterns between different orthosis styles and no orthosis conditions.
Main Methods:
- Surface electromyography (EMG) was used to measure motor unit recruitment in 17 women (aged 22-40).
- Muscle activity was recorded for five proximal muscle groups, wrist extensors, and wrist flexors.
- Participants performed a standardized movement while wearing two types of wrist extension orthoses and without any orthosis.
Main Results:
- Significant increases in motor unit recruitment were observed in four out of five proximal muscles and in wrist flexors when wearing either orthosis.
- No significant differences in proximal muscle group activity were found between the short and long orthosis conditions.
- Wrist flexor activity was significantly higher with orthosis use compared to no orthosis.
Conclusions:
- The use of wrist extension orthoses imposes additional biomechanical stress on proximal joint musculature.
- These findings suggest that clinicians should consider the potential impact on proximal joints when prescribing wrist extension orthoses.
- Particular caution is advised for patients with pre-existing proximal joint compromise.
