Tendon Transfers

The wrist and hand consist of numerous bones that provide structural support for surrounding tissues. The fingers and thumb are made up of bones called phalanges, interconnected by robust ligaments. Tendons, which link muscles to bones, are essential for movement.

The extensor tendons originate near the elbow and extend to the back of the fingers and thumb. As these tendons reach the fingers, they flatten and thin out, attaching to the phalanges through a complex mechanism that facilitates finger extension and fine motor movements.

Conversely, flexor tendons begin in the forearm, pass around the elbow, and extend to the palm side of the fingers and thumb. Each finger has two flexor tendons, while the thumb has one. Fibrous pulleys keep these tendons close to the phalanges during movement, optimizing their functionality for bending, grasping, and precise motions.

Hand function loss can arise from various issues affecting muscles and tendons directly or indirectly. These include paralysis, nerve injuries, tendon ruptures, and muscle atrophy. Nerve damage can result from direct trauma, spinal cord injuries, traumatic brain injuries, or neurological disorders like stroke, cerebral palsy, and multiple sclerosis. Additionally, conditions like rheumatoid arthritis can lead to tendon ruptures, while traumatic injuries or scar tissue from burns can sever muscles and tendons.

Injuries to the tendons may cause pain and swelling in the hand joints. You may experience difficulty straightening or bending your wrist, fingers, or thumb, and your finger joints may hyperextend, appearing crooked. Nerve injuries can lead to numbness and an inability to sense pain or temperature changes in the hand.

To diagnose a tendon injury, your doctor will assess your medical history and examine your upper extremity. It is crucial to inform your doctor of any injuries or neurological conditions you may have. A thorough examination will include evaluating joint strength, stability, and motion, alongside tests for sensation and blood flow to the area. X-rays may be necessary to identify bone fractures or other abnormalities.

Your doctor may also individually test each nerve to assess any injuries, utilizing nerve conduction studies to measure nerve function. These tests determine the injury site by stimulating the nerve at one point and measuring the impulse's travel time. Additionally, electromyography (EMG) may be performed using small needle electrodes to assess muscle function and identify any abnormalities.

Tendon transfers aim to restore lost hand functions through surgical procedures. The specific method used depends on the intended movement and the availability of functioning muscle and tendon units. Other options include specialized tools, splints, and prosthetics.

Before proceeding with tendon transfer surgery, certain conditions must be met: the joints must maintain flexibility, and the affected hand area should have some sensation. Nerve repair surgery may be necessary to restore sensation before the tendon transfer.

Healthy tendons with adequate strength and blood supply are selected for transfer, typically from areas where other tendons can still perform their function. Generally, a tendon is transferred to restore one specific movement and usually crosses only one joint.

Under anesthesia, the surgeon will create an incision to access the selected tendon(s) and the attachment site. The tendon will be prepared for transfer, possibly lengthened using grafts. The surgeon will carefully route the tendon to ensure optimal pull direction and check tension and function before securing it in place with stitches.

Post-surgery, patients will wear a splint or cast to immobilize the joints, allowing the tendon transfer to heal. The duration and degree of immobilization vary based on the procedure performed. Following this period, you will begin hand therapy rehabilitation, where your therapist will guide you through exercises to regain strength, motion, and functionality. Recovery can extend from six months to a year, with gains continuing over time.

While tendon transfers are effective for restoring function, the new tendon may not match the original tendon’s strength or functionality, and some functional loss at the donor site is expected. Recovery outcomes are individualized, and your doctor will provide specific expectations.