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Ulnar nerve palsies can also be divided into low or high lesions. The key functional deficits that the surgeon can address with tendon transfers caused by these injuries include the following:
      Low ulnar nerve deficits include clawing and loss of pinch strength.
      High ulnar nerve deficits include the addition of the loss of small, ring, and possibly middle finger flexion due to FDP paralysis.

The primary distinguishing feature between a high lesion and a low lesion is the involvement of the FDP to the ring and small fingers. In addition to the loss of motor control of the ulnar-innervated musculature, resulting in functional loss of precision finger positioning and power pinch, ulnar nerve palsy results in deformity and contractures. Although the ability for abduction and adduction of the fingers is lost with the paralysis of the interossei, this function is not a top priority for reconstruction and it is not one that is practical to achieve with tendon transfers. The …