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Subcutaneous Transposition of Ulnar Nerve

- See:
     - Ulnar Nerve:
     - Anatomy & Sites of Compression of Cubital Tunnel:

- Surgical Considerations:
    - transposition can entail subQ or submuscular transposition with excision of medial intermuscular septum, and release of 
           arcade of Struthers;
    - in the presence of H.O. the nerve should be placed in the subcutaneous position, since H.O. forms between muscle layers;
    - subcutaneous (or sub-muscular transposition) is also indicated to relieve tension following ulnar nerve repairs;
    - relative contra-indications:
           - thin patients w/ minimal subcutaneous tissue or scarring around the elbow, in which case a submuscular transposition;
    - outcomes:
           - in the report by Black BT, et al (2000) the authors compared the results of immediate and late 
                  institution of a range of motion postoperatively;
                  - 47 patients with 51 elbows were reexamined, by an investigator who had not been involved in their treatment;
                  - followup was a minimum of two years (range, twenty-four months to fourteen years) after an anterior transposition;
                  - of the 51 elbows, 21 were immobilized for 2 to 3 weeks whereas 30 were managed with an immediate ROM;
                  - there were occasional, mild paresthesias in 16% of the limbs and there was still subjective weakness of 19 %;
                  - both pinch and grip strength had increased substantially, and no patient had lost elbow motion.
                  - positive Tinel sign persisted in 31 % of the limbs, but it was mildly positive in most of them;
                  - elbow flexion test was uniformly negative;
                  -  results for 92% of the limbs were satisfactory to the patients, who stated that they would undergo the same procedure again;
                  - 73 % of the limbs had an excellent result; 18 %, a good result; 4 %, a fair result; and 6 %, a poor result;
                  - patients treated with a postoperative cast returned to work at an average of thirty days after surgery whereas the group 
                          treated with immediate motion of the elbow returned to work at an average of ten days;
                  - ref: Stabilized Subcutaneous Ulnar Nerve Transposition with Immediate Range of Motion. Long-Term Follow-up.  

- Anatomy & Sites of Compression

- Technique of Subcutaneous Transposition:
    - tourniquet is not generally necessary;
    - longitudinal incision is made just posterior to medial epicondyle;
    - take care to avoid branches of the medial antebrachial cutaneous nerve, especially in the distal portion of the wound (nerve is located 
          above the superficial fascia);
    - the ulnar nerve is identified and tagged just proximal to the epicondyle;
    - the ulnar nerve is followed proximally along the medial triceps;
    - attempt to leave the vessels which often accompany the nerve undisturbed;
    - arcade of Struther's:
          - may be found 8 cm above medial epicondyle;
          - if present, the arcade is divided;
    - intermuscular septum:
          - a portion of the medial intermuscular septum is excised just above the epicondyle;
          - be careful not to injure the median nerve and brachial artery which lie immediately anterior to the septum;
          - reference:
                 The relationship of the ulnar nerve to the medial intermuscular septum in the arm and its clinical significance.
    - cubital tunnel:
          - roof of cubital tunnel is formed by aponeurosic attachment of 2 heads of FCU, which spans in arcade like manner from medial 
                epicondyle of humerus to the olecranon process of the ulna (also known as Osborne's ligament);
                - cubital tunnel begins where the ulnar nerve passes beneath Osborne's ligament;
          - ulnar nerve reaches groove behind medial epicondyle accompanied by ulnar collateral artery;
                - anterior band of medial collateral ligament is anterior to ulnar nerve, which does not cross it;
          - branches to FCU & medial half of FDP are given off distal to entry of nerve into cubital tunnel, yet these 2 muscles are usually 
                spared in cubital tunnel syndrome;
    - ulnar nerve branches:
          - at the elbow joint look for branches off the nerve;
          - muscular branches to the FCU are identified and protected;
          - the articular branches are sacrificed;
    - FCU aponeurosis:
          - the superficial and deep aponeurosis covering both heads of the FCU is released into the proximal portion of the proximal forearm;
          - distal to humeral and ulnar FCU hiatus may be found a transverse arc of fascia;
          - inadequate release of this fascia may lead to iatrogenic compression, after the nerve has been transposed;
          - care is taken to avoid injuring the motor branches to the FCU;
    - nerve examination:
          - look for focal constriction of the nerve within the cubital tunnel;
          - if present, superficial fibrotic epineurium should be gently teased apart inorder to relax the constriction;
    - nerve transposition:
          - the nerve is transposed anteriorly;
          - the arcade of Struthers and medial intermuscular septum are re-checked to ensure that there is no secondary traction on the nerve;
          - the elbow is extended and the deep flexor-pronator fascia is palpated in order to determine whether there is any remaining 
                   constricting bands;

- Fascial Sling:
    - some type of fascial sling is necessary inorder to avoid ulnar nerve subluxation back over the medial epicondyle;
    - Eaton Fascio-Dermal Sling:
           - w/ subcutaneous transposition, a fascial sling needs to be constructed about 1 cm anterior to the medial epicondyle, in order to 
                  prevent the nerve from migrating back posteriorly;
           - clear off 4 cm of fascia anterior to the epicondyle separating it from subQ tissue (fascia cleared of flexor pronator origin);
           - a 2 cm wide by 3-4 cm trap door of fascia is created (left attached to the medial epicondyle);
           - look for an vertical intermuscular septae, and release them as appropriate (avoid iatrogenic compression);
           - after the nerve has been transposed, the fascial flap is sewn to the overlying subcutaneous tissue or deep dermal tissue (of the
                  opposite side of the wound) in such a way that no iatrogenic compression is created;
                  - this fascia band will prevent the nerve from falling backward;
           - reference:
                  - Anterior transposition of the ulnar nerve using a non compressing fasciodermal sling.  
    - Medial Intermuscular Septum as a Fascial Sling:
           - involves using the medial intermuscular septum into a fascial or fascial-dermal sling inorder to provide a restraint to posterior ulnar 
                  nerve subluxation;
           - the medial septum is divided 3-4 cm proximal to its insertion on the medial epicondyle;
                  - the width of this fascial band is approximately 1 cm;
                  - leave the septum attached to the medial epicondyle, but free all other attachments;
           - the free end of the divided intermuscular septum is sutured to the fascia of the flexor/pronator mass;
                  - as an alternative, the septum may be secured to the subcutaneous tissue;
           - reference:
                  - Use of the medial intermuscular septum as a fascial sling during anterior transposition of the ulnar nerve.

- Wound Closure:
          - prior to wound closure, stimulate the ulnar nerve to document that it is functioning

- Complications:
    - injury to medial antebrachial cutaneous nerve;
    - nerve ischemia:
           - may occur if nerve is freed from soft tissue attachments for more than 6-8 cm;
    - recurrent compression:
           - frequently due to unresected proximal structures such as medial intermuscular septum, or arcade of Struthers;
    - excessive scarring:
           - more common w/ intramuscular transposition;
    - local tenderness:
           - may be a minor problem in thin patients;
    - elbow flexion contracture:
           - may result from submuscular transposition

The failed ulnar nerve transposition. Etiology and treatment.

Technical problems with ulnar nerve transposition at the elbow: findings and results of reoperation.

Superficial anterior transposition of the ulnar nerve at the elbow for ulnar neuritis.

Anterior transposition of the ulnar nerve using a non-compressing fasciodermal sling.

Cadaveric study on the vascular anatomy of the ulnar nerve at the elbow--a basis for anterior transposition?

Severe ulnar neuropathy after subcutaneous transposition in a collegiate tennis player.

Use of the medial intermuscular septum as a fascial sling during anterior transposition of the ulnar nerve.