Tendon Transfer Surgery
Sometimes the nerves can be damaged to the extent that reconstruction or transplantation is not possible anymore. Should there be irreparable damage to muscles after an accident, then so-called tendon transfer can be performed.
This treatment method involves either rerouting the point of attachment of a healthy muscle (donor) to that of the target muscle (recipient), or the transfer of the entire muscle including its nerves and blood supply. In a so-called “free tissue transfer”, the muscle including tissues containing arteries and veins, and nerve branches are attached to the recipient using microvascular surgery. However, here there is the disadvantage that the nerve cells first have to regenerate into the target muscle via the suturing points in order to be a success. Therefore, the muscle initially loses strength as it is only indirectly innervated by externally applied electrical stimulation. This external stimulation must be applied regularly over a lengthy period of time because the regeneration speed of the new nerve, depending on age of the patient, is around 1mm per day.
The goal of this surgery is to achieve the greatest functionality possible in the hand. All the functions that cannot be compensated for by the training of other healthy muscles are attempted to be recovered by coupling paralysed muscles to healthy ones. Therefore, functionally less important muscles should take over and perform the tasks that other muscles cannot.
The thumb is indispensable in the performing of the grip function because of its ability to oppose (opposition of the thumb) the direction of movement of the other fingers. Therefore, should its function be lost then so-called opponensplasty is conducted. This involves rerouting of the flexor tendons in the ring finger to take over control of the thumb.
A further transfer surgery is the rerouting of one of the index finger’s extensor tendons to the long extensor tendon of the thumb. This tendon often ruptures in fractures to the radius (distal radius fractures, wrist fractures) because of the narrow constraints of the path the tendon must run through. However, sometimes tears to the extensor tendons of the thumb can be traced back to mechanical problems caused by implanted screws and plates.