Common Tendon Transfers

Synopsis

Tendon transfers can be used to restore hand and wrist function after a nerve injury, both in the acute setting and in delayed presentations. Injuries of the brachial plexus and peripheral motor nerves are common indications for tendon transfers. Alternatively, patients may have loss of a muscle-tendon unit (MTU) from trauma or after an oncologic resection; reconstruction with a tendon transfer can replace the function of the lost MTU. Tendon transfers can also restore function after attritional tendon ruptures, which are most commonly seen in rheumatoid arthritis.

Clinical Issues

Tendon transfers are used to restore the function of a paralyzed or lacerated MTU using a nearby functional MTU. They can be used in the upper and lower extremity. In the upper extremity, they are most commonly used to restore flexion and extension of the wrist and fingers and less frequently used for the shoulder and elbow.

Tendon transfers in the upper extremity can restore function after the loss of an MTU function caused by injury of the central or peripheral nervous system, closed rupture or open injury to the MTU, and various diseases. Infectious diseases, such as poliomyelitis, can cause damage to motor neuron ganglia and subsequent muscle paralysis. Inflammatory arthropathies, most commonly rheumatoid arthritis, can be complicated by attritional tendon ruptures. Some patients with hand spasticity, for example due to cerebral palsy, can benefit from carefully selected tendon transfers.

Patient presentation varies based on the etiology of the MTU loss. Mixed peripheral nerve injuries present with sensory and motor losses in the affected nerve distribution. Patients with traumatic MTU deficits have a history of injury to the affected MTU. Lacerations or fractures can result in discontinuity of an MTU. Primary MTU repair is preferred; however, if not possible or if unsuccessful, tendon transfers can be used for reconstruction. Nerve lacerations can be repaired acutely or can be reconstructed with nerve transfers up to approximately 12 months after injury; better outcomes are seen with earlier nerve surgery. In the case of a delayed nerve injury presentation or failed nerve repair, tendon transfers are options to restore function.

In rheumatoid arthritis, the ulnar dorsal tendons (extensor digiti minimum [EDM], extensor digitorum communis [EDC]) are most commonly ruptured, due to attrition over a dorsally prominent ulnar head. The flexor pollicis longus (FPL) can rupture due to chronic attrition over a volar osteophyte on the scaphoid known as a Mannerfelt lesion. Rheumatoid arthritis patients typically have systemic disease symptoms, and multiple joints are involved.

Traumatic nerve and MTU injuries affect the balance between the flexor and extensor muscle groups of the upper extremity. This can lead to asynchronous and weak function. Tendon grafts, tendon transfers, nerve transfers, and free muscle transfers can be used for upper-extremity reconstruction. The risks and benefits of each technique must be considered and each patient treated with an individualized plan.

Tendon transfers are reliable, with minimal donor site morbidity. They restore function early after surgery; range of motion (ROM) exercises are started 4 weeks post-operatively, and unrestricted activities are permitted 12 weeks post-operatively. In contrast, nerve transfers often require 6 to 9 months before clinical evidence of muscle reinnervation is seen and up to 2 to 3 years for maximal recovery. Local MTUs are transferred in tendon transfers, negating the need for microsurgery expertise and equipment that are needed for free muscle transfers. Tendon grafts can be used when there is a tendon gap in the MTU. However, when the MTU lacks innervation or is severely damaged, a tendon graft is insufficient to restore function, and a tendon transfer is required.

A careful physical examination documents missing functions and intact MTUs. In theory, any MTU can be transferred; however, donor site morbidity must be considered, and therefore certain MTUs are more appropriate for transfer than others ( Table 5.6.1 ). Synergistic transfers (such as the use of a wrist extensor for finger flexion) are the most intuitive for patients to learn and offer the quickest return of function ( Fig. 5.6.1 ). A redundant MTU is transferred that minimizes donor site morbidity while restoring a lost function. Finding an appropriate donor MTU is more difficult in combined nerve injuries because more muscles are affected, causing a greater number of functional deficits with fewer intact MTUs available for transfer.

Management

A comprehensive history and physical examination will identity the patient's functional deficits and their reconstructive goals. Selection of an appropriate donor MTU for transfer is important to restore function while minimizing donor site morbidity. The patient's handedness, occupation, and avocations are discussed. Any limitations in the patient's activities of daily living, recreation, and work are documented.

To determine the level of injury of the MTU, the skin is examined; any previous lacerations are noted. Acute tendon lacerations are typically repaired with direct tendon repair, but these injuries can be missed. Palpating for the point of maximal tenderness along the tendon can indicate the level of tendon injury and subsequent tendon retraction; this finding is most pronounced early after a tendon injury and can be absent in late presentations. For closed tendon ruptures, ultrasound can be helpful to determine the location of the injury. After a nerve injury, the MTU is in continuity, but lacks innervation.

To maximize the strength of the tendon transfer and to allow early active ROM, tendon transfers are best secured using 3 Pulvertaft weaves. The donor tendon is divided distally and the recipient tendon is divided proximally to facilitate adequate tendon weaving. Setting the tension of the tendon transfer is critical for restoration of function while preventing the loss of ROM of other joints. The tension is set with 1 Pulvertaft weave, and then the tenodesis effect is checked to ensure adequate ROM. Adjustments in tension can be made with the second and third Pulvertaft weaves. Each Pulvertaft weave is secured with a minimum of two non-absorbable sutures; we prefer to use 3-0 polyester suture.

Tendon transfers can be performed in an end-to-end or end-to-side fashion. End-to-end suturing facilitates a direct line of pull and is used if the recipient tendon is not expected to have any spontaneous recovery; for example, after complete denervation from an unrepaired nerve transection. If the nerve has been repaired and some muscle recovery is expected, the tendon transfer is performed in an end-to-side fashion to augment existing function.

Techniques