Tendon Transfers

Deborah A. Schwartz

Working with clients undergoing tendon transfer surgery is an incredibly exciting and rewarding process. As a therapist, you most likely will be working with individuals who sustained trauma or injuries resulting in compromised functional abilities. This trauma may have been a life-changing event and will require tremendous support and understanding on your part. Their progress from the initial incident toward independent function has plateaued. Or perhaps your client has never experienced great hand function due to congenital deformities. Tendon transfer surgery offers the possibility of improved or enhanced function for the client and, perhaps, a more independent lifestyle. The approach to tendon transfer surgery should be that of a team effort, involving the surgeon, client, you as therapist, and psychological support from social workers or psychologists as needed. You have an important role to play from the beginning and throughout the entire course of rehabilitation. During the pre-surgery assessment, you evaluate and record accurately all of the client’s functional abilities and progress. Only you can report to the team the details on what the client can and cannot do and what he clearly hopes to accomplish via the surgery. You also work as an educator to the client and his family, and you explain the entire process of the planned surgical procedures, including what to expect from every stage. You serve as active advocate as well, working with the surgeon to help clarify what is most important to your client in terms of recovery of functional activities. You can arrange for counseling as needed with the social worker or psychologist and help prepare the client for support services and postoperative employment opportunities. Do not hesitate to refer the client to their case manager (if this is a workman’s compensation case) or to their health insurance company to seek out these additional support services. Preoperative therapy sessions are devoted to conditioning, stretching the tissues and tight joints, and strengthening of the selected donor muscles. Postoperatively, you are the key rehabilitation specialist, having the most one-on-one contact with your client. Consider your work together as a partnership with your client to maximize progress and advance him toward his functional goals.

Indications

Tendon transfer surgery involves the operative repositioning of a tendon of a working muscle to take over the function of an absent or nonfunctioning muscle.¹ Tendon transfer surgery is, above all, an attempt to rebalance an imbalanced hand (Fig. 32-1).

FIGURE 32-1 Imbalanced hand due to radial nerve palsy.

Indications for tendon transfer surgery include imbalance in the hand caused by central neurologic deficits, such as seen in spinal cord injuries or cerebral palsy, or trauma to the upper extremity where nerves and tendons are lacerated or crushed and cannot be repaired.² Prolonged nerve compression can also lead to irreversible damage of muscle. Other causes for muscle imbalance are disease processes, such as poliomyelitis, rheumatoid arthritis, or Charcot Marie Tooth syndrome (which affects the intrinsic muscles of the hand causing wasting of the muscle fibers), and congenital deformities, such as those occurring with brachial plexus palsy or thumb hypoplasia.^2–5

Additional procedures might include a free muscle transfer⁶ where the entire muscle-tendon unit is transferred with intact nerve and blood supply preserved; neurotization, or nerve transfer,² which involves the implantation of a donor motor nerve into denervated vascularized muscle; or tenodesis,⁷ which is an automatic movement of a joint produced by a more proximal joint. A commonly cited example of tenodesis is demonstrated during active wrist extension when the digits and thumb fall naturally into flexion. Surgery can create or enhance a tenodesis effect by rerouting the transected tendon across a more proximal joint and attaching it there.

General Considerations

Alternative procedures may have been performed prior to tendon transfer surgery, such as nerve decompression, nerve repair, and muscle or tendon repair.¹ Tendon transfers may be considered as a restorative option when there is no further recovery or nerve regeneration from the precipitating event. Surgeons typically wait 3 to 4 months for this plateau to occur.^2–5

The prerequisites for this surgery are:1,2–5

• Analysis of client’s needs

• Bony stability

• Edema or inflammation have subsided

• Adequate soft tissue bed

• Mobile joints

• Expendable donor muscles (Muscles perform a certain function, but alternate muscles also perform the same function. The transfer of the expendable muscle does not in itself cause another deficit of motor function.)

• Functional sensation in the affected extremity

Additionally, although it is implied, it should be stated openly that a key component for the success of this elective surgery lies in the motivation and understanding of the client. Without clearly-defined functional goals and a willingness to work toward the outcome, the surgical procedure by itself will not lead to improved outcomes. The client must demonstrate active participation in the process.8,9

Clinical Pearl

The client needs to have an appreciation of the surgical expectations and limitations offered by tendon transfer surgery. Carefully explain to your client that the concept of “normal” hand function and/or appearance is unrealistic. Reinforce the key point that the goals of this surgery are to improve functional outcomes and independence.

The selection of the donor tendons must take into consideration the following:1,2–5,9

• A muscle that has sufficient strength to overcome the strength and passive tension of the antagonist muscle

• A muscle that lies in an appropriate direction of the desired action

• A muscle that travels a straight route and performs a single function

• Potential excursion of the muscle once it is freed from all connective tissue attachments

The muscle should contract through a distance about equal to the resting length of individual muscle fibers. The required excursion is the excursion needed to move a joint through its full range of motion (ROM), but the available excursion is limited by the surrounding connective tissue.¹

Additional considerations that come into play are the staging of multiple procedures on both the flexor and the extensor sides of the extremity, and the selection of alternative procedures, such as arthrodesis (joint fusion) and/or tenodesis. The rehabilitation plan typically immobilizes and protects the transfer during the first 3 to 4 weeks post-surgery.1,2–4,8,9

Preoperative Treatment

Clients with peripheral nerve injuries can benefit from therapeutic intervention while awaiting either nerve regeneration or restorative surgery. The fabrication of well-designed orthoses can greatly increase the functional capabilities of clients diagnosed with radial, median, and/or ulnar nerve palsies. Left unsupported, these nerve injuries can lead to significant joint contractures and overstretching of muscle tendon units.8–12 At a minimum, peripheral nerve injuries cause joint stiffness and discomfort, as well as awkward posturing. A variety of immobilization or mobilization orthoses can be fabricated for this purpose:

• Clients with radial nerve palsy require support of the wrist and metacarpophalangeal (MP) joints in extension (Fig. 32-2).

FIGURE 32-2 Dynamic orthosis for radial nerve palsy.

• Clients with median nerve palsy require support and positioning of the thumb in opposition and abduction for fine motor tasks (Fig. 32-3 and Fig. 32-4).

FIGURE 32-3 Client with adducted thumb due to median nerve palsy.

• Clients with ulnar nerve palsy require that the MP joints be positioned in flexion to prevent clawing of the ulnar digits and to substitute for lack of intrinsic function. If the median nerve is also involved, clients may require additional support for the thumb in abduction (Fig. 32-5 and Fig. 32-6).

FIGURE 32-5 Static anti-claw orthosis (figure-eight) for ulnar nerve palsy.

If the client has elected to proceed with tendon transfer surgery, therapeutic management includes the preoperative evaluation, conditioning, and client education.9,13 Unfortunately, many of the clients requiring hand therapy may not have been seen by you prior to their surgery. If this is the case with your client, you must work quickly and effectively to gain the client’s confidence and trust. But ideally, the entire process includes your contributions as the therapist, starting with the preoperative evaluation and coursing also through preoperative conditioning and education as well as postoperative rehabilitation. Working together for this extended time period reinforces the rapport between you and your client.

The Evaluation

Begin your evaluation with an interview to determine the client’s expectations of the outcomes from the planned surgery. When working with a child, meet and discuss this with the family as well. The evaluation should also include the following:

• Assess the client’s ability to comply with the postoperative rehabilitative protocol. It is helpful if you have already worked with the client through their post trauma rehabilitation, but you can still develop a rapport with the client at any point by explaining concepts; developing a working relationship as coach, educator, and partner; and forming a treatment plan geared toward function.

• Record a detailed history of the injury, all of the surgical procedures, and all of the therapy that has taken place up to this point, leading to the decision for tendon transfer surgery.

• Examine the affected extremity; observe and record the skin appearance and the placement of scars, adhesions, atrophy of muscles, prominent bony landmarks, and skin coloring.

• Determine sensory status using the Semmes-Weinstein monofilament test, two-point discrimination testing, and/or stereognosis testing.9,14 When working with children, you will need to closely observe how they integrate the use of their involved hand into play. You can incorporate a game of stereognosis to determine their ability to interpret sensory input in their involved hand. Stereognosis refers to the ability to perceive and recognize the form of an object using cues from its size and texture. Evaluating a child may be a bit more challenging, but it is possible through creative and interactive play and by discussing your observations of the use of the affected extremity with the parents.^9,13

• Take active range of motion (AROM) and passive range of motion (PROM) measurements. Evaluate each joint carefully to ascertain whether it has a hard or soft end feel, and note whether a contracture is present or if there is ligament laxity in the joint. If a contracture is present, you need to address this prior to surgery. If the joint is extremely lax, you should mention this to the surgeon so that the proper amount of tension can be applied during the surgery.

• Evaluate the current use of the hand through functional testing, such as the Jebsen Hand Function Test (JHFT), the functional dexterity test (FDT) (See Fig. 32-7), or the Moberg’s pickup test^9,15.

In addition to the above assessments, observe the client’s movement patterns, and note all of the compensatory movement patterns.11,14 These are patterns of movement that your client may have begun to use to make up for the lack of normally functioning muscles. These movement patterns can lead to overstretching and weakening of muscles that are not yet injured. You will need to retrain your client not to use these patterns of movement after surgery. It is best to point these patterns out early and teach your client to recognize them. Instruct your client to avoid these movement patterns in preparation for the surgery.

Include one of the following client self-report outcome measures: the Canadian Occupational Performance Measure (COPM), Disabilities of the Arm, Shoulder, and Hand (DASH) or QuickDASH, or the Michigan Hand Outcomes Questionnaire (MHQ).13–17 These self-assessments contribute crucial information to an overall picture of how the client rates their own independent functioning, and theyhelp determine how your client views progress toward achievement of functional goals throughout the rehabilitation process.

Tips from the Field

A video recording and/or clinical pictures can greatly assist you in recording the preoperative functional level. You can even use your own cell phone or the client’s cell phone to do this. Just make sure to ask permission first. This is a great tool for assessing compensatory movement patterns, checking progress, and comparing how the client was functioning prior to surgery and after surgery in the course of rehabilitation.

At the conclusion of the assessments, record a list of the greatest functional needs of the client in their own words. Ask what they would most like to do with their involved hand. Hold a hairbrush? Drink from a soda bottle? Hold a water bottle so that they can open the cap independently? Do not make the mistake of telling the client what these goals should be. Let the client define in their own words what would they would like to accomplish. In the case of young children, let the parents step in and describe what they would like to see.

Perform manual muscle testing (Table 32-1) to determine what muscles are indeed paralyzed and what muscles may act as donor muscles. It is important to ensure that all possible donor muscles are strong enough to be transferred to new positions.^2,4,13,18 Donor muscles should function at a grade of full ROM against gravity or higher.^1,9 Selecting the muscles that are typically described as donor muscles in textbooks as being available without verifying that they are present and active is not enough. Not everyone may have a palmaris longus (PL) tendon available for transfer!³

TABLE 32-1

Manual Muscle Testing

Grade	Terminology	Description
5	Normal	Full ROM and full strength
4	Good	Full ROM against gravity with some resistance
3	Fair	Full ROM against gravity
2	Poor	Full ROM with gravity eliminated
1	Trace	Slight contraction without joint movement
0	None	No evidence of contraction