The use of tendon transfer to restore functions of extremities was initially recognised in the 19th century, and its advancement was further amplified by the polio epidemic towards the turn of that century. Tendon transfer surgery extended to the use for traumatic reconstructive surgery during World War I, with key surgical pioneers, including Mayer, Sterling Bunnell, Guy Pulvertaft and Joseph Boyes. In 1921, Robert Jones first described the transfer of pronator teres (PT) to the wrist extensors for irreparable radial nerve paralysis in infantile hemiplegia. Although, a detailed description of its indication and surgical outcomes were not published until 1959 and 1970 by Stelling and Meyer, and Keats, respectively. Pronator teres is often the tendon of choice for reconstructing wrist extensors, and used in a multiple of pathologies, including radial nerve palsy, cerebral palsy, and tetraplegia. Reconstruction of finger extensors are less straightforward and options include flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), and flexor digitorum superficialis (FDS). Our article describes the techniques and outcomes of 25 patients that undergone pronator teres transfer. A good understanding of the pronator teres anatomical location and potential variations, aids efficient harvesting and limits unnecessary tissue dissection. Pronator teres tendon harvest is best performed through a systematic and anatomic approach.
During the 19th century, surgeon first recognised that transferring tendons could restore certain functional deficit in extremities, and its advancement was further amplified by the polio epidemic in Europe at the turn of that century, which saw a significant raise in patients suffering from limb paralysis. Key surgical pioneers, such as Leo Mayer, Sterling Bunnell, Guy Pulvertaft and Joseph Boyes, expanded tendon transfer surgery, not only to those with paralysis from polio and cerebral palsy, but those with significant traumatic limb injuries endured during World War I [
In 1921, Robert Jones described the first pronator teres (PT) transfer to wrist extensors for irreparable radial nerve paralysis in infantile hemiplegia, although a detailed description of indication and outcomes were not published until later by Stelling and Meyer in 1959, and by Keats in 1970. Pronator teres tendontransfer is most often used for wrist extensor reconstruction, commonly using the tendon of extensor carpi radialis brevis (ECRB) as attachment, and for patients with radial nerve palsy, cerebral palsy, or tetraplegia, [
In radial nerve injury the greatest functional loss is grip weakness, an early PT to ECRB transfer (along with nerve repair) is recommended to eliminate the need for an external splint, as it acts as a dynamic splint during nerve regeneration. Authors have highlighted that this type of tendon transfer does not interfere with the recovery of radial nerve injury and supported this approach. The Merle d’Aubigné procedure isone of the technique used for the treatment of irreversible radial palsy, and describes the transfer of PT to ECRB and extensor carpi radialis longus (ECRL), FCU to the extensor pollicis longus (EPL) and extensor digitorum communis (EDC), palmaris longus (PL) to extensor pollicis brevis (EPB) and abductor pollicislongus (APL) [
The word pronator comes from the Latin pronus and translate to “inclined forward or lying face downward”, which describes the action of pronator teres on the forearm. The Latin term teres means “round or cylindrical shaped” or “long and round”, which describes the shape of the muscle. PT is located on the volar aspect of the forearm, and functions to rotate the forearm palm-down (pronation) with pronator quadratus (PQ). The muscle originates from two heads (humeral and ulnar) and attaches onto the lateral aspect of the radius. The humeral head is larger and shallower, and begins above the medial epicondyle, at the medial supracondylar ridge with the other common flexor tendons. The ulnar head originates below the elbow on the medial aspect of the coronoid process of the ulna. The two heads come together, cross the forearm diagonally, and insert halfway down the lateral surface of the radius via a tendon.
A rare variant of a high-humeral origin had been reported by some authors, arising from an existing supracondylar process of the humerus and a fibrous band extending between the supracondylar process and the medial epicondyle―the ligament of Struthers. This variation often coexists with a variation of the musculocutaneous nerve [
Patient position is supine with arm tourniquet inflated up to physiological pressure around 80 - 100 mmHg. Local an aesthesia marcaine 0.25% with 1:200.000 adrenaline is infiltrated around skin incision. The PT tendon is approached through a straight skin incision on the upper lateral aspect of the forearm, and its attachment to the radial shaft could be traced underneath the brachioradialis (BR) muscle from the volar aspect. An amount of radial periosteum is usually raised with the PT tendon.
Pronator Teres to ECRB and ERCLFrom the dorsal aspect of the BR, the ECRB and ERCL tendons are identified. The fascia surrounding the PT is released and if necessary proximal origin “z” cut is used to improve the line of pull and muscle excursion. The detached PT tendon is brought through a tunnel under the sheath of the brachioradialis muscle to the dorsal aspect, and tightly weaved (Pulvertaft) onto the ECRB and ECRL tendons in a combined manner with the wrist in maximal extension, using non-absorbable polyester sutures. The upper limb is immobilised for 3 weeks to allow the tendon transfer site to heal, followed by active rehabilitation to improve movement and gliding of the transfer. Cognitive rehabilitation is started after 6 weeks to recover stimulus-response curves and proper excitability of cortical and subcortical inputs.
It is reasonable to expecta weakened wrist extension and reduced range of wrist flexion in patients who had PT to ECRBL transfer. No studies had reported forearm pronation weakness after PT transfer, as pronator quadratus and oppositional supinator compensates for the absence of PT function. Rarer complications include dehiscence of dorsal forearm wound, which can heal secondarily without intervention. Aggressive traction to the nerve can lead to altered sensibility and dysesthesias of radial nerve distribution, and proximal release of the fascia surrounding the muscle can cause iatrogenic damage to the radial artery [
The use of PT tendon transfer to restore wrist extensor function is well recognised, and most commonly performed by transferring the PT onto the ERCB tendon. The fibre lengths and muscle shape of the two muscles are nearly identical, which suggests comparable power capacity and lengthening ability, suitable to inter-exchanging [
De Leo, A., Leung, B.C. and Giele, H. (2016) Techniques in Hand & Upper Extremity Surgery. Open Journal of Orthopedics, 6, 321-325. http://dx.doi.org/10.4236/ojo.2016.610042
Pronator Teres―PT;
Flexor Carpi Radialis―FCR;
Flexor Carpi Ulnaris―FCU;
Flexor Digitorum Superficialis―FDS.