The incidence of obstetric brachial plexus palsy (OBPP) ranges globally from 0.5 to 2 per 1000 births with the higher numbers in under developed countries. A majority of them progress to complete recovery, other may improve slowly but incompletely. The rate of complete, spontaneous recovery varies in the literature from 30 % to 95 %. Factors associated with OBPP include large birth weight, breech delivery and shoulder dystocia.
Microsurgical reconstruction of OBPP is a relatively new area of work in the peripheral nerve surgery. There is a great dispute amongst the clinicians regarding the surgical indications and timing of surgery. Many still advise the parents to adhere with the physiotherapy programme even for the cases not showing recovery after a reasonable period of time. This ultimately leaves many children with deformities in the shoulder, elbow and forearm. Such children are unable to perform self care activities, such as grooming, feeding and washing themselves, because of limited active external rotation, abduction, elbow flexion, and pronation contracture in forearm. These children, though, will improve significantly with the muscle release and tendon transfer surgery, but results will always be inferior to a primary nerve surgery performed in the early infantile age.
In this lateral decubitus position, a longitudinal incision is made along the lateral border of the scapula and dissection is carried down to the latissimus dorsi muscle, the fibres of which cover the lateral aspect of scapula. This muscle is retracted inferiorly and the inferior angle of scapula is stabilized with a strong suture or towel clips.
The subscapularis muscle is elevated from the anterior surface of the scapula with the use of electrocautery or a periosteal elevator. Dissection is performed in a subperiosteal fashion, progressing from the inferior angle upwards. An external rotatory force on the humerus is applied through out
the release to confirm adequate release. Care is taken to avoid injury to the subscapularis vessels and nerve running from anteromedial to the glenoid neck and anterior to the subscapularis muscle as well as injury to suprascapular vessels and nerve running from anterior to posterior over the scapular notch. The wound is closed over a suction drain and arm splinted to abduction and external rotation. This splint is maintained full time for three months, removing it only to bath and for gentle range of motion exercises, which are begun at 6 weeks.
Transfer of the conjoint tendon of latissimus dorsi and teres major to the rotator cuff
The patient is placed in the lateral decubitus position. An incision is made in the axilla in a transverse direction. Pectoralis major muscle, if contracted, is released from its insertion. If the pectoralis muscle is not contracted, a single transverse incision is made in the posterior axilla. Subscapularis muscle is released if indicated. The tendons of latissimus dorsi and teres major are released with protection of radial nerve and the contents of the quadrilateral space. The interval between the posteroinferior margin of deltoid muscle and the rotator cuff is developed and the arm is maximally abducted and externally rotated. The released tendons of the latissimus dosri and the teres major are next transferred posterior to the long head of the triceps muscle and sutured as superiorly as possible to the rotator cuff.Two longitudinal incisions are made in the cuff, and the tendons are pulled through these incisions and sutured to themselves, thereby converting the latissimus dorsi and teres major muscles in to external rotators of the shoulder. A shoulder spica is fitted with the shoulder in 60 to 90 degrees of abduction and external rotation. This splint is continued full time for three months and only at night for an additional three months.
Lateral shifting of clavicular origin of pectoralis major and transfer of teres major muscle to the infraspinatus muscle
Clavicular orgin of pectoralalis major is erased from the clavicle and after mobilization sutured to the periosteum on the later third of the clavicle. Through a posterior incision, teres major muscle is divided at its insertion, separated from the latissimus dorsi muscle and sutured superiorly to the infraspinatus muscle. Immobilization is maintained as per the previous techniques.
Derotation Osteotomy of the humerus
Through an anterior incision in the deltopectoral groove with its extension into upper arm, proximal humerus is exposed between the anterior border of the deltoid and the biceps. The osteotomy is performed between the insertions of the pectoralis major and the deltoid. The elbow is maintained in a flexed position while the distal fragment of the humerus is rotated laterally and kept adjacent to the body until the hand could be brought to the mouth. Osteotomy site is fixed with a 4 or 5 hole plate with screws.No drains were kept. A plaster spica is applied with the shoulder in 90 degrees of abduction and full external rotation, the elbow in 90 degrees of flexion and the forearm in full supination. The cast is maintained for 6 weeks.