Assessment of Flexor carpi ulnaris function for tendon transfer surgery

Active and passive length–force curves of spastic flexor carpi ulnaris (FCU) muscles were intra-operatively measured in 10 patients with cerebral palsy to study the variability in FCU muscle function. Maximum active FCU force was in general situated near the neutral position of the wrist and varied between 40 and 135 N. Passive forces varied between 1 and 8 N at maximum active force. The potential active excursion varied between 4 and 7 cm, while patients moved their wrists from flexion to extension along different parts of the active length–force curve. We measured a large inter-individual variety of spastic FCU muscle function in this group of patients. Thus, tailoring the surgical technique of tendon transfer to the specific needs of the desired function requires the assessment of muscle-specific data for each individual patient.