Procedure 24 Superficialis-to-Profundus Tendon Transfer
Indications
This procedure is indicated for fixed finger deformities secondary to flexor digitorum superficialis and flexor digitorum profundus tendon spasticity. The muscle properties have been permanently altered owing to the contracture severity and chronicity.
These patients have marked functional impairment and have expected limited upper extremity use. The procedure is often used for facilitating skin care and hand hygiene problems.
The determination between this type of transfer and a fractional lengthening needs to be evaluated by preoperative assessment. Comanagement with the family and caregivers is essential for identifying the preoperative needs.
It should be explained that finger stiffness is common after surgery and that a different type of contracture may be present. The position of the contracture is changed to a posture that aids in maintaining hygiene and overall care.
Examination/Imaging
Clinical Examination
Preoperative evaluation is important to determine the contribution of the different volar flexor muscles to the finger contracture. Examine finger extension at both maximum wrist flexion and maximum wrist extension.
The finger flexion deformity will be worse with maximum wrist extension than with maximum wrist flexion if the deformity is secondary to contracture of the flexor digitorum superficialis and flexor digitorum profundus tendons. In different neurologic conditions, the wrist flexor musculature may also be spastic.
Assess the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints of each digit because fixed contractures may require concomitant treatment (closed manipulation, open capsulotomies, or joint fusions).
Surgical Anatomy
Pertinent surgical structures include all volar forearm muscles (palmaris longus, flexor carpi radialis [FCR], flexor carpi ulnaris [FCU], flexor digitorum superficialis [FDS], flexor digitorum profundus [FDP], pronator teres, pronator quadratus), median nerve, ulnar nerve and artery, and radial artery.
Positioning
The patient is positioned supine with the arm extended onto a surgical arm board.
A nonsterile tourniquet is placed high on the arm to permit better manipulation of the elbow during the procedure. If an elbow procedure is also necessary, a sterile tourniquet is used. Visualization of the volar forearm can be difficult if there is elbow flexion and forearm pronation contracture. In these instances, sterile bumps are necessary under the dorsal forearm. General anesthesia with muscle relaxation is also helpful to overcome the deforming force of the pronator teres.
Exposures
A longitudinal volar forearm approach from the mid-forearm to the proximal wrist crease is used.
The FDS and FDP need to be visualized from the level of the musculotendinous junction to the level of the entrance into the carpal tunnel. The incision should be extended as necessary to identify the flexor tendons and median nerve (Fig. 24-1).
Meticulous hemostasis is necessary with ligation of the small perforating vessels (Fig. 24-2).